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1.	Akiyama, Kazunori, et al. (författare) First M87 Event Horizon Telescope Results. VII. Polarization of the Ring 2021 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 910:1 Tidskriftsartikel (refereegranskat)abstract In 2017 April, the Event Horizon Telescope (EHT) observed the near-horizon region around the supermassive black hole at the core of the M87 galaxy. These 1.3 mm wavelength observations revealed a compact asymmetric ring-like source morphology. This structure originates from synchrotron emission produced by relativistic plasma located in the immediate vicinity of the black hole. Here we present the corresponding linear-polarimetric EHT images of the center of M87. We find that only a part of the ring is significantly polarized. The resolved fractional linear polarization has a maximum located in the southwest part of the ring, where it rises to the level of similar to 15%. The polarization position angles are arranged in a nearly azimuthal pattern. We perform quantitative measurements of relevant polarimetric properties of the compact emission and find evidence for the temporal evolution of the polarized source structure over one week of EHT observations. The details of the polarimetric data reduction and calibration methodology are provided. We carry out the data analysis using multiple independent imaging and modeling techniques, each of which is validated against a suite of synthetic data sets. The gross polarimetric structure and its apparent evolution with time are insensitive to the method used to reconstruct the image. These polarimetric images carry information about the structure of the magnetic fields responsible for the synchrotron emission. Their physical interpretation is discussed in an accompanying publication.
2.	Akiyama, Kazunori, et al. (författare) First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon 2021 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 910:1 Tidskriftsartikel (refereegranskat)abstract Event Horizon Telescope (EHT) observations at 230 GHz have now imaged polarized emission around the supermassive black hole in M87 on event-horizon scales. This polarized synchrotron radiation probes the structure of magnetic fields and the plasma properties near the black hole. Here we compare the resolved polarization structure observed by the EHT, along with simultaneous unresolved observations with the Atacama Large Millimeter/submillimeter Array, to expectations from theoretical models. The low fractional linear polarization in the resolved image suggests that the polarization is scrambled on scales smaller than the EHT beam, which we attribute to Faraday rotation internal to the emission region. We estimate the average density n(e) similar to 10(4-7) cm(-3), magnetic field strength B similar to 1-30 G, and electron temperature T-e similar to (1-12) x 10(10) K of the radiating plasma in a simple one-zone emission model. We show that the net azimuthal linear polarization pattern may result from organized, poloidal magnetic fields in the emission region. In a quantitative comparison with a large library of simulated polarimetric images from general relativistic magnetohydrodynamic (GRMHD) simulations, we identify a subset of physical models that can explain critical features of the polarimetric EHT observations while producing a relativistic jet of sufficient power. The consistent GRMHD models are all of magnetically arrested accretion disks, where near-horizon magnetic fields are dynamically important. We use the models to infer a mass accretion rate onto the black hole in M87 of (3-20) x 10(-4) M yr(-1).
3.	Akiyama, Kazunori, et al. (författare) First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration 2022 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2 Tidskriftsartikel (refereegranskat)abstract We present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A), collected during the 2017 April 5-11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account for Sgr A's flux variability. The majority of the 1.3 mm emission arises from horizon scales, where intrinsic structural source variability is detected on timescales of minutes to hours. The effects of interstellar scattering on the image and its variability are found to be subdominant to intrinsic source structure. The calibrated visibility amplitudes, particularly the locations of the visibility minima, are broadly consistent with a blurred ring with a diameter of similar to 50 mu as, as determined in later works in this series. Contemporaneous multiwavelength monitoring of Sgr A* was performed at 22, 43, and 86 GHz and at near-infrared and X-ray wavelengths. Several X-ray flares from Sgr A* are detected by Chandra, one at low significance jointly with Swift on 2017 April 7 and the other at higher significance jointly with NuSTAR on 2017 April 11. The brighter April 11 flare is not observed simultaneously by the EHT but is followed by a significant increase in millimeter flux variability immediately after the X-ray outburst, indicating a likely connection in the emission physics near the event horizon. We compare Sgr A*'s broadband flux during the EHT campaign to its historical spectral energy distribution and find that both the quiescent emission and flare emission are consistent with its long-term behavior.
4.	Akiyama, Kazunori, et al. (författare) First Sagittarius A* Event Horizon Telescope Results. III. Imaging of the Galactic Center Supermassive Black Hole 2022 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2 Tidskriftsartikel (refereegranskat)abstract We present the first event-horizon-scale images and spatiotemporal analysis of Sgr A* taken with the Event Horizon Telescope in 2017 April at a wavelength of 1.3 mm. Imaging of Sgr A* has been conducted through surveys over a wide range of imaging assumptions using the classical CLEAN algorithm, regularized maximum likelihood methods, and a Bayesian posterior sampling method. Different prescriptions have been used to account for scattering effects by the interstellar medium toward the Galactic center. Mitigation of the rapid intraday variability that characterizes Sgr A* has been carried out through the addition of a "variability noise budget" in the observed visibilities, facilitating the reconstruction of static full-track images. Our static reconstructions of Sgr A* can be clustered into four representative morphologies that correspond to ring images with three different azimuthal brightness distributions and a small cluster that contains diverse nonring morphologies. Based on our extensive analysis of the effects of sparse (u, v)-coverage, source variability, and interstellar scattering, as well as studies of simulated visibility data, we conclude that the Event Horizon Telescope Sgr A* data show compelling evidence for an image that is dominated by a bright ring of emission with a ring diameter of similar to 50 mu as, consistent with the expected "shadow" of a 4 x 10(6) M (circle dot) black hole in the Galactic center located at a distance of 8 kpc.
5.	Akiyama, Kazunori, et al. (författare) First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass 2022 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2 Tidskriftsartikel (refereegranskat)abstract In this paper we quantify the temporal variability and image morphology of the horizon-scale emission from Sgr A, as observed by the EHT in 2017 April at a wavelength of 1.3 mm. We find that the Sgr A data exhibit variability that exceeds what can be explained by the uncertainties in the data or by the effects of interstellar scattering. The magnitude of this variability can be a substantial fraction of the correlated flux density, reaching similar to 100% on some baselines. Through an exploration of simple geometric source models, we demonstrate that ring-like morphologies provide better fits to the Sgr A* data than do other morphologies with comparable complexity. We develop two strategies for fitting static geometric ring models to the time-variable Sgr A* data; one strategy fits models to short segments of data over which the source is static and averages these independent fits, while the other fits models to the full data set using a parametric model for the structural variability power spectrum around the average source structure. Both geometric modeling and image-domain feature extraction techniques determine the ring diameter to be 51.8 +/- 2.3 mu as (68% credible intervals), with the ring thickness constrained to have an FWHM between similar to 30% and 50% of the ring diameter. To bring the diameter measurements to a common physical scale, we calibrate them using synthetic data generated from GRMHD simulations. This calibration constrains the angular size of the gravitational radius to be 4.8(-0.7)(+1.4) mu as, which we combine with an independent distance measurement from maser parallaxes to determine the mass of Sgr A* to be 4.0(-0.6)(+1.1) x 10(6) M-circle dot.
6.	Akiyama, Kazunori, et al. (författare) First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole 2022 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2 Tidskriftsartikel (refereegranskat)abstract In this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohydrodynamics simulations, including aligned, tilted, and stellar-wind-fed simulations; radiative transfer is performed assuming both thermal and nonthermal electron distribution functions. We test the models against 11 constraints drawn from EHT 230 GHz data and observations at 86 GHz, 2.2 mu m, and in the X-ray. All models fail at least one constraint. Light-curve variability provides a particularly severe constraint, failing nearly all strongly magnetized (magnetically arrested disk (MAD)) models and a large fraction of weakly magnetized models. A number of models fail only the variability constraints. We identify a promising cluster of these models, which are MAD and have inclination i <= 30 degrees. They have accretion rate (5.2-9.5) x 10(-9) M (circle dot) yr(-1), bolometric luminosity (6.8-9.2) x 10(35) erg s(-1), and outflow power (1.3-4.8) x 10(38) erg s(-1). We also find that all models with i >= 70 degrees fail at least two constraints, as do all models with equal ion and electron temperature; exploratory, nonthermal model sets tend to have higher 2.2 mu m flux density; and the population of cold electrons is limited by X-ray constraints due to the risk of bremsstrahlung overproduction. Finally, we discuss physical and numerical limitations of the models, highlighting the possible importance of kinetic effects and duration of the simulations.
7.	Akiyama, Kazunori, et al. (författare) First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric 2022 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2 Tidskriftsartikel (refereegranskat)abstract Astrophysical black holes are expected to be described by the Kerr metric. This is the only stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies Einstein's equations and does not have pathologies outside of the event horizon. We present new constraints on potential deviations from the Kerr prediction based on 2017 EHT observations of Sagittarius A* (Sgr A). We calibrate the relationship between the geometrically defined black hole shadow and the observed size of the ring-like images using a library that includes both Kerr and non-Kerr simulations. We use the exquisite prior constraints on the mass-to-distance ratio for Sgr A to show that the observed image size is within similar to 10% of the Kerr predictions. We use these bounds to constrain metrics that are parametrically different from Kerr, as well as the charges of several known spacetimes. To consider alternatives to the presence of an event horizon, we explore the possibility that Sgr A* is a compact object with a surface that either absorbs and thermally reemits incident radiation or partially reflects it. Using the observed image size and the broadband spectrum of Sgr A*, we conclude that a thermal surface can be ruled out and a fully reflective one is unlikely. We compare our results to the broader landscape of gravitational tests. Together with the bounds found for stellar-mass black holes and the M87 black hole, our observations provide further support that the external spacetimes of all black holes are described by the Kerr metric, independent of their mass.
8.	Broderick, Avery E., et al. (författare) Characterizing and Mitigating Intraday Variability: Reconstructing Source Structure in Accreting Black Holes with mm-VLBI 2022 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2 Tidskriftsartikel (refereegranskat)abstract The extraordinary physical resolution afforded by the Event Horizon Telescope has opened a window onto the astrophysical phenomena unfolding on horizon scales in two known black holes, M87* and Sgr A. However, with this leap in resolution has come a new set of practical complications. Sgr A exhibits intraday variability that violates the assumptions underlying Earth aperture synthesis, limiting traditional image reconstruction methods to short timescales and data sets with very sparse (u, v) coverage. We present a new set of tools to detect and mitigate this variability. We develop a data-driven, model-agnostic procedure to detect and characterize the spatial structure of intraday variability. This method is calibrated against a large set of mock data sets, producing an empirical estimator of the spatial power spectrum of the brightness fluctuations. We present a novel Bayesian noise modeling algorithm that simultaneously reconstructs an average image and statistical measure of the fluctuations about it using a parameterized form for the excess variance in the complex visibilities not otherwise explained by the statistical errors. These methods are validated using a variety of simulated data, including general relativistic magnetohydrodynamic simulations appropriate for Sgr A* and M87. We find that the reconstructed source structure and variability are robust to changes in the underlying image model. We apply these methods to the 2017 EHT observations of M87, finding evidence for variability across the EHT observing campaign. The variability mitigation strategies presented are widely applicable to very long baseline interferometry observations of variable sources generally, for which they provide a data-informed averaging procedure and natural characterization of inter-epoch image consistency.
9.	Issaoun, Sara, et al. (författare) Resolving the Inner Parsec of the Blazar J1924-2914 with the Event Horizon Telescope 2022 Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 934:2 Tidskriftsartikel (refereegranskat)abstract The blazar J1924-2914 is a primary Event Horizon Telescope (EHT) calibrator for the Galactic center's black hole Sagittarius A*. Here we present the first total and linearly polarized intensity images of this source obtained with the unprecedented 20 mu as resolution of the EHT. J1924-2914 is a very compact flat-spectrum radio source with strong optical variability and polarization. In April 2017 the source was observed quasi-simultaneously with the EHT (April 5-11), the Global Millimeter VLBI Array (April 3), and the Very Long Baseline Array (April 28), giving a novel view of the source at four observing frequencies, 230, 86, 8.7, and 2.3 GHz. These observations probe jet properties from the subparsec to 100 pc scales. We combine the multifrequency images of J1924-2914 to study the source morphology. We find that the jet exhibits a characteristic bending, with a gradual clockwise rotation of the jet projected position angle of about 90 degrees between 2.3 and 230 GHz. Linearly polarized intensity images of J1924-2914 with the extremely fine resolution of the EHT provide evidence for ordered toroidal magnetic fields in the blazar compact core.
10.	Wielgus, Maciek, et al. (författare) Millimeter Light Curves of Sagittarius A* Observed during the 2017 Event Horizon Telescope Campaign 2022 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2 Tidskriftsartikel (refereegranskat)abstract The Event Horizon Telescope (EHT) observed the compact radio source, Sagittarius A* (Sgr A), in the Galactic Center on 2017 April 5-11 in the 1.3 mm wavelength band. At the same time, interferometric array data from the Atacama Large Millimeter/submillimeter Array and the Submillimeter Array were collected, providing Sgr A light curves simultaneous with the EHT observations. These data sets, complementing the EHT very long baseline interferometry, are characterized by a cadence and signal-to-noise ratio previously unattainable for Sgr A* at millimeter wavelengths, and they allow for the investigation of source variability on timescales as short as a minute. While most of the light curves correspond to a low variability state of Sgr A, the April 11 observations follow an X-ray flare and exhibit strongly enhanced variability. All of the light curves are consistent with a red-noise process, with a power spectral density (PSD) slope measured to be between -2 and -3 on timescales between 1 minute and several hours. Our results indicate a steepening of the PSD slope for timescales shorter than 0.3 hr. The spectral energy distribution is flat at 220 GHz, and there are no time lags between the 213 and 229 GHz frequency bands, suggesting low optical depth for the event horizon scale source. We characterize Sgr A's variability, highlighting the different behavior observed just after the X-ray flare, and use Gaussian process modeling to extract a decorrelation timescale and a PSD slope. We also investigate the systematic calibration uncertainties by analyzing data from independent data reduction pipelines.
11.	Akiyama, Kazunori, et al. (författare) First M87 Event Horizon Telescope Results. IX. Detection of Near-horizon Circular Polarization 2023 Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 957:2 Tidskriftsartikel (refereegranskat)abstract Event Horizon Telescope (EHT) observations have revealed a bright ring of emission around the supermassive black hole at the center of the M87 galaxy. EHT images in linear polarization have further identified a coherent spiral pattern around the black hole, produced from ordered magnetic fields threading the emitting plasma. Here we present the first analysis of circular polarization using EHT data, acquired in 2017, which can potentially provide additional insights into the magnetic fields and plasma composition near the black hole. Interferometric closure quantities provide convincing evidence for the presence of circularly polarized emission on event-horizon scales. We produce images of the circular polarization using both traditional and newly developed methods. All methods find a moderate level of resolved circular polarization across the image (〈\|v\|〉 < 3.7%), consistent with the low image-integrated circular polarization fraction measured by the Atacama Large Millimeter/submillimeter Array (\|vint\| < 1%). Despite this broad agreement, the methods show substantial variation in the morphology of the circularly polarized emission, indicating that our conclusions are strongly dependent on the imaging assumptions because of the limited baseline coverage, uncertain telescope gain calibration, and weakly polarized signal. We include this upper limit in an updated comparison to general relativistic magnetohydrodynamic simulation models. This analysis reinforces the previously reported preference for magnetically arrested accretion flow models. We find that most simulations naturally produce a low level of circular polarization consistent with our upper limit and that Faraday conversion is likely the dominant production mechanism for circular polarization at 230 GHz in M87*
12.	Algaba, Juan-Carlos, et al. (författare) Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign 2021 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1 Forskningsöversikt (refereegranskat)abstract In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
13.	Bott, Lukas Thomas, et al. (författare) Coulomb dissociation of O-16 into He-4 and C-12 2023 Ingår i: NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022. - : EDP Sciences. - 2100-014X. ; 279 Konferensbidrag (refereegranskat)abstract We measured the Coulomb dissociation of O-16 into He-4 and C-12 within the FAIR Phase-0 program at GSI Helmholtzzentrum fur Schwerionenforschung Darmstadt, Germany. From this we will extract the photon dissociation cross section O-16(alpha,gamma)C-12, which is the time reversed reaction to C-12(alpha,gamma)O-16. With this indirect method, we aim to improve on the accuracy of the experimental data at lower energies than measured so far. The expected low cross section for the Coulomb dissociation reaction and close magnetic rigidity of beam and fragments demand a high precision measurement. Hence, new detector systems were built and radical changes to the (RB)-B-3 setup were necessary to cope with the high-intensity O-16 beam. All tracking detectors were designed to let the unreacted O-16 ions pass, while detecting the C-12 and He-4.
14.	Docherty, Anna R, et al. (författare) GWAS Meta-Analysis of Suicide Attempt: Identification of 12 Genome-Wide Significant Loci and Implication of Genetic Risks for Specific Health Factors. 2023 Ingår i: The American journal of psychiatry. - : American Psychiatric Association Publishing. - 1535-7228 .- 0002-953X. ; 180:10, s. 723-738 Tidskriftsartikel (refereegranskat)abstract Suicidal behavior is heritable and is a major cause of death worldwide. Two large-scale genome-wide association studies (GWASs) recently discovered and cross-validated genome-wide significant (GWS) loci for suicide attempt (SA). The present study leveraged the genetic cohorts from both studies to conduct the largest GWAS meta-analysis of SA to date. Multi-ancestry and admixture-specific meta-analyses were conducted within groups of significant African, East Asian, and European ancestry admixtures.This study comprised 22 cohorts, including 43,871 SA cases and 915,025 ancestry-matched controls. Analytical methods across multi-ancestry and individual ancestry admixtures included inverse variance-weighted fixed-effects meta-analyses, followed by gene, gene-set, tissue-set, and drug-target enrichment, as well as summary-data-based Mendelian randomization with brain expression quantitative trait loci data, phenome-wide genetic correlation, and genetic causal proportion analyses.Multi-ancestry and European ancestry admixture GWAS meta-analyses identified 12 risk loci at p values <5×10-8. These loci were mostly intergenic and implicated DRD2, SLC6A9, FURIN, NLGN1, SOX5, PDE4B, and CACNG2. The multi-ancestry SNP-based heritability estimate of SA was 5.7% on the liability scale (SE=0.003, p=5.7×10-80). Significant brain tissue gene expression and drug set enrichment were observed. There was shared genetic variation of SA with attention deficit hyperactivity disorder, smoking, and risk tolerance after conditioning SA on both major depressive disorder and posttraumatic stress disorder. Genetic causal proportion analyses implicated shared genetic risk for specific health factors.This multi-ancestry analysis of suicide attempt identified several loci contributing to risk and establishes significant shared genetic covariation with clinical phenotypes. These findings provide insight into genetic factors associated with suicide attempt across ancestry admixture populations, in veteran and civilian populations, and in attempt versus death.
15.	Farah, Joseph, et al. (författare) Selective Dynamical Imaging of Interferometric Data 2022 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2 Tidskriftsartikel (refereegranskat)abstract Recent developments in very long baseline interferometry (VLBI) have made it possible for the Event Horizon Telescope (EHT) to resolve the innermost accretion flows of the largest supermassive black holes on the sky. The sparse nature of the EHT's (u, v)-coverage presents a challenge when attempting to resolve highly time-variable sources. We demonstrate that the changing (u, v)-coverage of the EHT can contain regions of time over the course of a single observation that facilitate dynamical imaging. These optimal time regions typically have projected baseline distributions that are approximately angularly isotropic and radially homogeneous. We derive a metric of coverage quality based on baseline isotropy and density that is capable of ranking array configurations by their ability to produce accurate dynamical reconstructions. We compare this metric to existing metrics in the literature and investigate their utility by performing dynamical reconstructions on synthetic data from simulated EHT observations of sources with simple orbital variability. We then use these results to make recommendations for imaging the 2017 EHT Sgr A* data set.
16.	Georgiev, Boris, et al. (författare) A Universal Power-law Prescription for Variability from Synthetic Images of Black Hole Accretion Flows 2022 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2 Tidskriftsartikel (refereegranskat)abstract We present a framework for characterizing the spatiotemporal power spectrum of the variability expected from the horizon-scale emission structure around supermassive black holes, and we apply this framework to a library of general relativistic magnetohydrodynamic (GRMHD) simulations and associated general relativistic ray-traced images relevant for Event Horizon Telescope (EHT) observations of Sgr A. We find that the variability power spectrum is generically a red-noise process in both the temporal and spatial dimensions, with the peak in power occurring on the longest timescales and largest spatial scales. When both the time-averaged source structure and the spatially integrated light-curve variability are removed, the residual power spectrum exhibits a universal broken power-law behavior. On small spatial frequencies, the residual power spectrum rises as the square of the spatial frequency and is proportional to the variance in the centroid of emission. Beyond some peak in variability power, the residual power spectrum falls as that of the time-averaged source structure, which is similar across simulations; this behavior can be naturally explained if the variability arises from a multiplicative random field that has a steeper high-frequency power-law index than that of the time-averaged source structure. We briefly explore the ability of power spectral variability studies to constrain physical parameters relevant for the GRMHD simulations, which can be scaled to provide predictions for black holes in a range of systems in the optically thin regime. We present specific expectations for the behavior of the M87 and Sgr A* accretion flows as observed by the EHT.
17.	Goddi, Ciriaco, et al. (författare) Polarimetric Properties of Event Horizon Telescope Targets from ALMA 2021 Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 910:1 Tidskriftsartikel (refereegranskat)abstract We present the results from a full polarization study carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) during the first Very Long Baseline Interferometry (VLBI) campaign, which was conducted in 2017 April in the lambda 3 mm and lambda 1.3 mm bands, in concert with the Global mm-VLBI Array (GMVA) and the Event Horizon Telescope (EHT), respectively. We determine the polarization and Faraday properties of all VLBI targets, including Sgr A, M87, and a dozen radio-loud active galactic nuclei (AGNs), in the two bands at several epochs in a time window of 10 days. We detect high linear polarization fractions (2%-15%) and large rotation measures (RM > 10(3.3)-10(5.5) rad m(-2)), confirming the trends of previous AGN studies at millimeter wavelengths. We find that blazars are more strongly polarized than other AGNs in the sample, while exhibiting (on average) order-of-magnitude lower RM values, consistent with the AGN viewing angle unification scheme. For Sgr A we report a mean RM of (-4.2 0.3) x 10(5) rad m(-2) at 1.3 mm, consistent with measurements over the past decade and, for the first time, an RM of (-2.1 0.1) x 10(5) rad m(-2) at 3 mm, suggesting that about half of the Faraday rotation at 1.3 mm may occur between the 3 mm photosphere and the 1.3 mm source. We also report the first unambiguous measurement of RM toward the M87 nucleus at millimeter wavelengths, which undergoes significant changes in magnitude and sign reversals on a one year timescale, spanning the range from -1.2 to 0.3 x 10(5) rad m(-2) at 3 mm and -4.1 to 1.5 x 10(5) rad m(-2) at 1.3 mm. Given this time variability, we argue that, unlike the case of Sgr A*, the RM in M87 does not provide an accurate estimate of the mass accretion rate onto the black hole. We put forward a two-component model, comprised of a variable compact region and a static extended region, that can simultaneously explain the polarimetric properties observed by both the EHT (on horizon scales) and ALMA (which observes the combined emission from both components). These measurements provide critical constraints for the calibration, analysis, and interpretation of simultaneously obtained VLBI data with the EHT and GMVA.
18.	Kim, Jae-Young, et al. (författare) Event Horizon Telescope imaging of the archetypal blazar 3C 279 at an extreme 20 microarcsecond resolution 2020 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 640 Tidskriftsartikel (refereegranskat)abstract 3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique - global Very Long Baseline Interferometry (VLBI) at 1.3mm (230 GHz) - to resolve the innermost jet of 3C 279 in order to study its fine-scale morphology close to the jet base where highly variable-ray emission is thought to originate, according to various models. The source was observed during four days in April 2017 with the Event Horizon Telescope at 230 GHz, including the phased Atacama Large Millimeter/submillimeter Array, at an angular resolution of ∼20 μas (at a redshift of z = 0:536 this corresponds to ∼0:13 pc ∼ 1700 Schwarzschild radii with a black hole mass MBH = 8 × 108 M⊙). Imaging and model-fitting techniques were applied to the data to parameterize the fine-scale source structure and its variation.We find a multicomponent inner jet morphology with the northernmost component elongated perpendicular to the direction of the jet, as imaged at longer wavelengths. The elongated nuclear structure is consistent on all four observing days and across diffierent imaging methods and model-fitting techniques, and therefore appears robust. Owing to its compactness and brightness, we associate the northern nuclear structure as the VLBI "core". This morphology can be interpreted as either a broad resolved jet base or a spatially bent jet.We also find significant day-to-day variations in the closure phases, which appear most pronounced on the triangles with the longest baselines. Our analysis shows that this variation is related to a systematic change of the source structure. Two inner jet components move non-radially at apparent speeds of ∼15 c and ∼20 c (∼1:3 and ∼1:7 μas day-1, respectively), which more strongly supports the scenario of traveling shocks or instabilities in a bent, possibly rotating jet. The observed apparent speeds are also coincident with the 3C 279 large-scale jet kinematics observed at longer (cm) wavelengths, suggesting no significant jet acceleration between the 1.3mm core and the outer jet. The intrinsic brightness temperature of the jet components are ≤1010 K, a magnitude or more lower than typical values seen at ≥7mm wavelengths. The low brightness temperature and morphological complexity suggest that the core region of 3C 279 becomes optically thin at short (mm) wavelengths.
19.	Narayan, Ramesh, et al. (författare) The Polarized Image of a Synchrotron-emitting Ring of Gas Orbiting a Black Hole 2021 Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 912:1 Tidskriftsartikel (refereegranskat)abstract Synchrotron radiation from hot gas near a black hole results in a polarized image. The image polarization is determined by effects including the orientation of the magnetic field in the emitting region, relativistic motion of the gas, strong gravitational lensing by the black hole, and parallel transport in the curved spacetime. We explore these effects using a simple model of an axisymmetric, equatorial accretion disk around a Schwarzschild black hole. By using an approximate expression for the null geodesics derived by Beloborodov and conservation of the Walker-Penrose constant, we provide analytic estimates for the image polarization. We test this model using currently favored general relativistic magnetohydrodynamic simulations of M87, using ring parameters given by the simulations. For a subset of these with modest Faraday effects, we show that the ring model broadly reproduces the polarimetric image morphology. Our model also predicts the polarization evolution for compact flaring regions, such as those observed from Sgr A with GRAVITY. With suitably chosen parameters, our simple model can reproduce the EVPA pattern and relative polarized intensity in Event Horizon Telescope images of M87*. Under the physically motivated assumption that the magnetic field trails the fluid velocity, this comparison is consistent with the clockwise rotation inferred from total intensity images.
20.	Paraschos, Georgios Filippos, et al. (författare) Ordered magnetic fields around the 3C 84 central black hole 2024 Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 682 Tidskriftsartikel (refereegranskat)abstract Context . 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz. Aims. Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84. Methods . We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure. Results . We report the detection of a highly ordered, strong magnetic field around the central, supermassive black hole of 3C 84. The brightness temperature analysis suggests that the system is in equipartition. We also determined a turnover frequency of νm = (113 ± 4) GHz, a corresponding synchrotron self-absorbed magnetic field of BSSA = (2.9 ± 1.6) G, and an equipartition magnetic field of Beq = (5.2 ± 0.6) G. Three components are resolved with the highest fractional polarisation detected for this object (mnet = (17.0 ± 3.9)%). The positions of the components are compatible with those seen in low-frequency VLBI observations since 2017-2018. We report a steeply negative slope of the spectrum at 228 GHz. We used these findings to test existing models of jet formation, propagation, and Faraday rotation in 3C 84. Conclusions . The findings of our investigation into different flow geometries and black hole spins support an advection-dominated accretion flow in a magnetically arrested state around a rapidly rotating supermassive black hole as a model of the jet-launching system in the core of 3C 84. However, systematic uncertainties due to the limited (u, v)-coverage, however, cannot be ignored. Our upcoming work using new EHT data, which offer full imaging capabilities, will shed more light on the compact region of 3C 84.
21.	Psaltis, Dimitrios, et al. (författare) Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole 2020 Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 125:14 Tidskriftsartikel (refereegranskat)abstract The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak-field tests can lead to large deviations in the predicted black-hole shadows that are inconsistent with even the current EHT measurements. We use numerical calculations of regular, parametric, non-Kerr metrics to identify the common characteristic among these different parametrizations that control the predicted shadow size. We show that the shadow-size measurements place significant constraints on deviation parameters that control the second post-Newtonian and higher orders of each metric and are, therefore, inaccessible to weak-field tests. The new constraints are complementary to those imposed by observations of gravitational waves from stellar-mass sources.
22.	Roelofs, F., et al. (författare) Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes 2023 Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 957:2 Tidskriftsartikel (refereegranskat)abstract The Event Horizon Telescope (EHT) is a millimeter very long baseline interferometry (VLBI) array that has imaged the apparent shadows of the supermassive black holes M87* and Sagittarius A. Polarimetric data from these observations contain a wealth of information on the black hole and accretion flow properties. In this work, we develop polarimetric geometric modeling methods for mm-VLBI data, focusing on approaches that fit data products with differing degrees of invariance to broad classes of calibration errors. We establish a fitting procedure using a polarimetric “m-ring” model to approximate the image structure near a black hole. By fitting this model to synthetic EHT data from general relativistic magnetohydrodynamic models, we show that the linear and circular polarization structure can be successfully approximated with relatively few model parameters. We then fit this model to EHT observations of M87 taken in 2017. In total intensity and linear polarization, the m-ring fits are consistent with previous results from imaging methods. In circular polarization, the m-ring fits indicate the presence of event-horizon-scale circular polarization structure, with a persistent dipolar asymmetry and orientation across several days. The same structure was recovered independently of observing band, used data products, and model assumptions. Despite this broad agreement, imaging methods do not produce similarly consistent results. Our circular polarization results, which imposed additional assumptions on the source structure, should thus be interpreted with some caution. Polarimetric geometric modeling provides a useful and powerful method to constrain the properties of horizon-scale polarized emission, particularly for sparse arrays like the EHT.
23.	Satapathy, Kaushik, et al. (författare) The Variability of the Black Hole Image in M87 at the Dynamical Timescale 2022 Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 925:1 Tidskriftsartikel (refereegranskat)abstract The black hole images obtained with the Event Horizon Telescope (EHT) are expected to be variable at the dynamical timescale near their horizons. For the black hole at the center of the M87 galaxy, this timescale (5-61 days) is comparable to the 6 day extent of the 2017 EHT observations. Closure phases along baseline triangles are robust interferometric observables that are sensitive to the expected structural changes of the images but are free of station-based atmospheric and instrumental errors. We explored the day-to-day variability in closure-phase measurements on all six linearly independent nontrivial baseline triangles that can be formed from the 2017 observations. We showed that three triangles exhibit very low day-to-day variability, with a dispersion of similar to 3 degrees-5 degrees. The only triangles that exhibit substantially higher variability (similar to 90 degrees-180 degrees) are the ones with baselines that cross the visibility amplitude minima on the u-v plane, as expected from theoretical modeling. We used two sets of general relativistic magnetohydrodynamic simulations to explore the dependence of the predicted variability on various black hole and accretion-flow parameters. We found that changing the magnetic field configuration, electron temperature model, or black hole spin has a marginal effect on the model consistency with the observed level of variability. On the other hand, the most discriminating image characteristic of models is the fractional width of the bright ring of emission. Models that best reproduce the observed small level of variability are characterized by thin ring-like images with structures dominated by gravitational lensing effects and thus least affected by turbulence in the accreting plasmas.
24.	Wielgus, Maciek, et al. (författare) Monitoring the Morphology of M87* in 2009-2017 with the Event Horizon Telescope 2020 Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 901:1 Tidskriftsartikel (refereegranskat)abstract The Event Horizon Telescope (EHT) has recently delivered the first resolved images of M87, the supermassive black hole in the center of the M87 galaxy. These images were produced using 230 GHz observations performed in 2017 April. Additional observations are required to investigate the persistence of the primary image feature-a ring with azimuthal brightness asymmetry-and to quantify the image variability on event horizon scales. To address this need, we analyze M87 data collected with prototype EHT arrays in 2009, 2011, 2012, and 2013. While these observations do not contain enough information to produce images, they are sufficient to constrain simple geometric models. We develop a modeling approach based on the framework utilized for the 2017 EHT data analysis and validate our procedures using synthetic data. Applying the same approach to the observational data sets, we find the M87* morphology in 2009-2017 to be consistent with a persistent asymmetric ring of similar to 40 mu as diameter. The position angle of the peak intensity varies in time. In particular, we find a significant difference between the position angle measured in 2013 and 2017. These variations are in broad agreement with predictions of a subset of general relativistic magnetohydrodynamic simulations. We show that quantifying the variability across multiple observational epochs has the potential to constrain the physical properties of the source, such as the accretion state or the black hole spin.
25.	Broderick, Avery E., et al. (författare) THEMIS: A Parameter Estimation Framework for the Event Horizon Telescope 2020 Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 897:2 Tidskriftsartikel (refereegranskat)abstract The Event Horizon Telescope (EHT) provides the unprecedented ability to directly resolve the structure and dynamics of black hole emission regions on scales smaller than their horizons. This has the potential to critically probe the mechanisms by which black holes accrete and launch outflows, and the structure of supermassive black hole spacetimes. However, accessing this information is a formidable analysis challenge for two reasons. First, the EHT natively produces a variety of data types that encode information about the image structure in nontrivial ways; these are subject to a variety of systematic effects associated with very long baseline interferometry and are supplemented by a wide variety of auxiliary data on the primary EHT targets from decades of other observations. Second, models of the emission regions and their interaction with the black hole are complex, highly uncertain, and computationally expensive to construct. As a result, the scientific utilization of EHT observations requires a flexible, extensible, and powerful analysis framework. We present such a framework, Themis, which defines a set of interfaces between models, data, and sampling algorithms that facilitates future development. We describe the design and currently existing components of Themis, how Themis has been validated thus far, and present additional analyses made possible by Themis that illustrate its capabilities. Importantly, we demonstrate that Themis is able to reproduce prior EHT analyses, extend these, and do so in a computationally efficient manner that can efficiently exploit modern high-performance computing facilities. Themis has already been used extensively in the scientific analysis and interpretation of the first EHT observations of M87.
26.	Eatough, Ralph P., et al. (författare) Verification of Radiative Transfer Schemes for the EHT 2020 Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 897:2 Tidskriftsartikel (refereegranskat)abstract The Event Horizon Telescope (EHT) Collaboration has recently produced the first resolved images of the central supermassive black hole in the giant elliptical galaxy M87. Here we report on tests of the consistency and accuracy of the general relativistic radiative transfer codes used within the collaboration to model M87∗ and Sgr A∗. We compare and evaluate (1) deflection angles for equatorial null geodesics in a Kerr spacetime; (2) images calculated from a series of simple, parameterized matter distributions in the Kerr metric using simplified emissivities and absorptivities; (3) for a subset of codes, images calculated from general relativistic magnetohydrodynamics simulations using different realistic synchrotron emissivities and absorptivities; (4) observables for the 2017 configuration of EHT, including visibility amplitudes and closure phases. The error in total flux is of order 1% when the codes are run with production numerical parameters. The dominant source of discrepancies for small camera distances is the location and detailed setup of the software "camera"that each code uses to produce synthetic images. We find that when numerical parameters are suitably chosen and the camera is sufficiently far away the images converge and that for given transfer coefficients, numerical uncertainties are unlikely to limit parameter estimation for the current generation of EHT observations. The purpose of this paper is to describe a verification and comparison of EHT radiative transfer codes. It is not to verify EHT models more generally.
27.	Jakobsson, J., et al. (författare) Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1 2021 Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 17:1, s. 1-382 Tidskriftsartikel (refereegranskat)
28.	Jang, Seon-Kyeong, et al. (författare) Rare genetic variants explain missing heritability in smoking. 2022 Ingår i: Nature human behaviour. - : Springer Science and Business Media LLC. - 2397-3374. ; 6:11, s. 1577-1586 Tidskriftsartikel (refereegranskat)abstract Common genetic variants explain less variation in complex phenotypes than inferred from family-based studies, and there is a debate on the source of this 'missing heritability'. We investigated the contribution of rare genetic variants to tobacco use with whole-genome sequences from up to 26,257 unrelated individuals of European ancestries and 11,743 individuals of African ancestries. Across four smoking traits, single-nucleotide-polymorphism-based heritability ([Formula: see text]) was estimated from 0.13 to 0.28 (s.e., 0.10-0.13) in European ancestries, with 35-74% of it attributable to rare variants with minor allele frequencies between 0.01% and 1%. These heritability estimates are 1.5-4 times higher than past estimates based on common variants alone and accounted for 60% to 100% of our pedigree-based estimates of narrow-sense heritability ([Formula: see text], 0.18-0.34). In the African ancestry samples, [Formula: see text] was estimated from 0.03 to 0.33 (s.e., 0.09-0.14) across the four smoking traits. These results suggest that rare variants are important contributors to the heritability of smoking.
29.	Mullins, Niamh, et al. (författare) Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors 2022 Ingår i: Biological Psychiatry. - : Elsevier. - 0006-3223 .- 1873-2402. ; 91:3, s. 313-327 Tidskriftsartikel (refereegranskat)abstract BACKGROUND: Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders.METHODS: We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors.RESULTS: Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged.CONCLUSIONS: Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.
30.	Roelofs, F., et al. (författare) SYMBA: An end-to-end VLBI synthetic data generation pipeline: Simulating Event Horizon Telescope observations of M 87 2020 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 636 Tidskriftsartikel (refereegranskat)abstract Context. Realistic synthetic observations of theoretical source models are essential for our understanding of real observational data. In using synthetic data, one can verify the extent to which source parameters can be recovered and evaluate how various data corruption effects can be calibrated. These studies are the most important when proposing observations of new sources, in the characterization of the capabilities of new or upgraded instruments, and when verifying model-based theoretical predictions in a direct comparison with observational data. Aims. We present the SYnthetic Measurement creator for long Baseline Arrays (SYMBA), a novel synthetic data generation pipeline for Very Long Baseline Interferometry (VLBI) observations. SYMBA takes into account several realistic atmospheric, instrumental, and calibration effects. Methods. We used SYMBA to create synthetic observations for the Event Horizon Telescope (EHT), a millimetre VLBI array, which has recently captured the first image of a black hole shadow. After testing SYMBA with simple source and corruption models, we study the importance of including all corruption and calibration effects, compared to the addition of thermal noise only. Using synthetic data based on two example general relativistic magnetohydrodynamics (GRMHD) model images of M 87, we performed case studies to assess the image quality that can be obtained with the current and future EHT array for different weather conditions. Results. Our synthetic observations show that the effects of atmospheric and instrumental corruptions on the measured visibilities are significant. Despite these effects, we demonstrate how the overall structure of our GRMHD source models can be recovered robustly with the EHT2017 array after performing calibration steps, which include fringe fitting, a priori amplitude and network calibration, and self-calibration. With the planned addition of new stations to the EHT array in the coming years, images could be reconstructed with higher angular resolution and dynamic range. In our case study, these improvements allowed for a distinction between a thermal and a non-thermal GRMHD model based on salient features in reconstructed images.
31.	Niemi, MEK, et al. (författare) 2021 swepub:Mat__t
32.	Ahlberg Tidblad, Annika, et al. (författare) Future Material Developments for Electric Vehicle Battery Cells Answering Growing Demands from an End-User Perspective 2021 Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:14 Forskningsöversikt (refereegranskat)abstract Nowadays, batteries for electric vehicles are expected to have a high energy density, allow fast charging and maintain long cycle life, while providing affordable traction, and complying with stringent safety and environmental standards. Extensive research on novel materials at cell level is hence needed for the continuous improvement of the batteries coupled towards achieving these requirements. This article firstly delves into future developments in electric vehicles from a technology perspective, and the perspective of changing end-user demands. After these end-user needs are defined, their translation into future battery requirements is described. A detailed review of expected material developments follows, to address these dynamic and changing needs. Developments on anodes, cathodes, electrolyte and cell level will be discussed. Finally, a special section will discuss the safety aspects with these increasing end-user demands and how to overcome these issues.
33.	Borrion, Hervé, et al. (författare) The Problem with Crime Problem-Solving : Towards a Second Generation Pop? 2020 Ingår i: British Journal of Criminology. - : Oxford University Press (OUP). - 0007-0955 .- 1464-3529. ; 60:1, s. 219-240 Tidskriftsartikel (refereegranskat)abstract In his 2018 Stockholm prize winner lecture, Goldstein highlighted the need for problem-oriented policing (POP) to be not only effective but also fair. Contributing to the development of POP, this study examines how a wider perspective on problem-solving generally, and scoping in particular, can be adopted to address some of the growing challenges in 21st century policing. We demonstrate that the concept of ‘problem’ was too narrowly defined and that, as a result, many problem-solving models found in criminology are ill-structured to minimize the negative side-effects of interventions and deliver broader benefits. Problem-solving concepts and models are compared across disciplines and recommendations are made to improve POP, drawing on examples in architecture, conservation science, industrial ecology and ethics.
34.	Dincel, Seren, et al. (författare) Light formed through urban morphology and different organism groups: First findings from a systematic review. 2024 Ingår i: IOP Conference Series. - : IOP Publishing. - 1755-1307 .- 1755-1315. ; 1320, s. 1-12 Tidskriftsartikel (refereegranskat)abstract The prevailing implementation and usage of contemporary lighting technologies and design practices in cities have created over-illuminated built environments. Recent studies indicate that exposure to electric lighting effects formed through spatial characteristics has visual, physiological, and behavioural effects on both humans and non-humans, such as wildlife. In order to gain a better understanding of the impact that electric lighting has on space and different organism groups, a comprehensive literature review was conducted applying PRISMA 2020 systematic review guidelines. Results of the searches from various databases, such as Web of Science, PubMed and Scopus, identified 5260 related studies. A total of 55 papers connected to four themes: (1) urban morphology; (2) human visual impressions; (3) ecological impacts; and (4) design approaches and methods were analysed with a focus on urban morphology. The review provided the following general findings: lighting properties alone are inadequate to depict visual impressions of pedestrians, patterns formed through light interacting with spatial characteristics can contribute to understanding how spaces are visually perceived and help characterising the exposure of wildlife organisms to potential disturbances.
35.	Eronen, Minna (författare) Maps for the layered gaps : Tools for affording situational awareness towards human inclusive place design 2024 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)
36.	Fagerholm, Nora, et al. (författare) Analysis of pandemic outdoor recreation and green infrastructure in Nordic cities to enhance urban resilience 2022 Ingår i: npj Urban Sustainability. - : Springer Nature. - 2661-8001. ; 2:1 Tidskriftsartikel (refereegranskat)abstract Recent empirical research has confirmed the importance of green infrastructure and outdoor recreation to urban people’s well- being during the COVID-19 pandemic. However, only a few studies provide cross-city analyses. We analyse outdoor recreation behaviour across four Nordic cities ranging from metropolitan areas to a middle-sized city. We collected map based survey data from residents (n = 469–4992) in spring 2020 and spatially analyse green infrastructure near mapped outdoor recreation sites and respondents’ places of residence. Our statistical examination reveals how the interplay among access to green infrastructure across cities and at respondents’ residential location, together with respondents’ socio-demographic profiles and lockdown policies or pandemic restrictions, affects outdoor recreation behaviour. The results highlight that for pandemic resilience, the history of Nordic spatial planning is important. To support well-being in exceptional situations as well as in the long term, green infrastructure planning should prioritise nature wedges in and close to cities and support small-scale green infrastructure
37.	Feng, Chen, et al. (författare) Accessibility patterns based on steps, direction changes, and angular deviation : Are they consistent? 2022 Ingår i: Proceedings: 13th International Space Syntax Symposium. - : Western Norway University of Applied sciences. ; , s. 534:1-20 Konferensbidrag (refereegranskat)abstract Modeling spaces and their relationships is at the core of syntactic analysis, including reach analysis. In a syntactic model, two spaces can be described as close together or far apart based on the directional distance between them. In this study, we compare three different ways of measuring directional distance—namely, by number of steps, by number of direction changes, and by angular deviation—in the context of accessibility and reach analysis. By graphically showing how choosing a different way of measuring directional distance can result in a different reach or accessibility pattern, we provide an intuitive understanding of the different natures of the syntactic measures. By demonstrating how the modeling conventions and the geometric composition of lines at a local scale can have a huge impact on the results of syntactic analysis at a larger scale, we call for more attention to the conventions and principles used for modeling street networks.
38.	Frieler, Katja, et al. (författare) Scenario setup and forcing data for impact model evaluation and impact attribution within the third round of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3a) 2024 Ingår i: Geoscientific Model Development. - : Copernicus Publications. - 1991-959X .- 1991-9603. ; 17:1, s. 1-51 Tidskriftsartikel (refereegranskat)abstract This paper describes the rationale and the protocol of the first component of the third simulation round of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3a, http://www.isimip.org, last access: 2 November 2023) and the associated set of climate-related and direct human forcing data (CRF and DHF, respectively). The observation-based climate-related forcings for the first time include high-resolution observational climate forcings derived by orographic downscaling, monthly to hourly coastal water levels, and wind fields associated with historical tropical cyclones. The DHFs include land use patterns, population densities, information about water and agricultural management, and fishing intensities. The ISIMIP3a impact model simulations driven by these observation-based climate-related and direct human forcings are designed to test to what degree the impact models can explain observed changes in natural and human systems. In a second set of ISIMIP3a experiments the participating impact models are forced by the same DHFs but a counterfactual set of atmospheric forcings and coastal water levels where observed trends have been removed. These experiments are designed to allow for the attribution of observed changes in natural, human, and managed systems to climate change, rising CH4 and CO2 concentrations, and sea level rise according to the definition of the Working Group II contribution to the IPCC AR6.
39.	Frykholm, Hannes, 1982- (författare) Building the city from the inside : architecture and urban transformation in Los Angeles, Porto, and Las Vegas 2020 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Positioned in the research field of “interior urbanism” (Rice, 2016), this thesis considers entrance situations that occur between buildings and cities in order to develop new ways of investigating the relationship between architecture and urban transformation. From the main research question—How does architecture mediate urban transformation?—the thesis focuses on experience-driven narratives about the city (Pine & Gilmore, 2011). Looking at the means by which architecture situates the subject in an urban experience, the thesis asks how the experience contributes to a particular attention to the city. This approach intends to shed light on architecture’s role in both mediating and challenging neoliberal urbanism (Peck, Theodore, & Brenner, 2009; Fraser, 2019). The thesis argues for analyzing large-scale processes of urban transformation by placing a sharpened empirical focus on the built environment. This is tested by a transversal research method (Frichot, Gabrielsson, Havik, & Jobst, forthcoming) that intersects multiple investigative techniques. The three cases that are addressed—the Westin Bonaventure Hotel in Los Angeles, the Casa da Música in Porto, and Wynn Casino in Las Vegas—each epitomize a particular discourse about architecture and urbanization. Through observations and the analysis of the three cases, the thesis unpacks three dimensions of architectural experience of the city: first, by highlighting the spatial logic of a stretched threshold; second, by considering temporality and ways of waiting; and third, by observing the labor that is necessary to keep the interior environment intact. A recurring narrative in these buildings lies in the suggestion that the process of urban redevelopment never ends. Together, the cases point to an oft-overlooked parallel between the refurbishment of building interiors and exterior urban transformations, adding empirical nuances to what has been labelled the “architecture of neoliberalism” (Spencer, 2016). The threshold between building and city is shown to be a fragile and unstable territory, which is under continuous negotiation and where the claims of multiple actors, conditions, and events come together. The thesis attempts to make a contribution in three ways: by developing transversal methods, by considering the threshold as knowledge device, and by exploring micro-scale investigations of urban transformation. The project points to how the stretched threshold of these projects speak of a transforming relationship between architecture and capitalism, where the city is reconfigured through the stretching of interiors out to adjacent sidewalks and squares. If the city is built from the expanding insides of architecture, the city is by definition an unfinished project. To think of the instability of architecture not as a shortcoming but as a virtue opens up for a continuous engagement with the city as the unfinished construction site of a democratic project.
40.	Jämlik livsmiljö : Universell utformning och tillgänglighet som stadsbyggnadsutmaning 2022 Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract Tillgänglighet finns inte i den fysiska miljön eller enskilda individen, utan uppstår i relationen mellan människa och miljö. Det forskningsprojekt den här rapporten grundar sig på utgår från studier av variationer i tillgänglighet för olika människor. Den utgår också från att tillgänglighet inte bara är lokal utan även en systemfråga – både i form av rumsliga system och i samhällets styr- och planeringssystem.I ett rumsligt systemperspektiv kan vad som lokalt ter sig som små skillnader ha stora effekter på systemnivå och tvärt om. Samtidigt handlar tillgänglighet till olika resurser också om hur de fördelas och distribueras. Detta gör att frågan behöver hanteras i samverkan mellan såväl olika förvaltningar som mellan kommunens planeringsverksamhet och andra aktörer. Därmed blir styrning och ledning av arbetet såväl inom kommunal planering som i samverkan avgörande.Rapporten består som helhet av fyra delar: en ”kappa” som omger tre delstudier. Kappan beskriver övergripande reflektioner och lärdommar från projektet, och följs i slutet av rapporten av ett appendix som innehåller reflektioner kring digitalisering och en engelsk sammanfattning. De tre studier som finns där emellan är en studie av Björn Hellström om processtyrning och ledning, Ann Legeby om modell och metod och Daniel Koch om systemvärld, livsvärld, och materiell värld.Projektet som helhet bidrar till både teori och metodutveckling. Det gör det genom att utveckla och pröva nya analysmetoder, genom att analysera och kritiskt diskutera styrdokument och processer, och genom att lägga rekommendationer utifrån detta. Det målar också upp en problembildoch utmaning kring vad som behöver vidareutvecklas och fördjupas, och pekar mot områden där kommunala processer och system kan utvecklas. En vikig genomgående observation i alla delstudier är just vikten av samverkan: mellan förvaltningar, mellan förvaltning och politisk styrning, och mellan planeringsverksamhet och det omgivande samhället.Ett viktigt bidrag är de steg som tas i projektet mot att möjliggöra att universell utformning kan bli mer konkret relevant och integrerat som strategisk fråga på översiktsplanenivå.
41.	Koch, Daniel, 1976- (författare) Configuration, geometry and spatial choreography 2021 Ingår i: Architecture, Perception, Curation. - Atlanta : Georgia Institute of Technology. ; , s. 64-66 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract Here, I engage with architecture from a perspective related to Judith Butler’s discussion of performativity as structures-in-the making. The relation of local, spatial situatedness to the extended structuring of social relations is of particular interest. This needs to be done with care since, as Nick Kaye notes, architectural space is not a precise enough symbolic system to form statements with distinct meanings, nor abstract and systemic enough to form a structure or lexicon. This leads to an ongoing negotiation of situatedness with space and architecture as active participants. While, for instance, a stage holds a range of possible, probable, and potential meanings and is embedded with sets of (expected and suggested) social relations, the particular meaning of that stage in a particular situation will always-ever be a matter of contextual, situated meaning-making. This does not leave architecture innocent; rather, it is precisely because such situations are dynamic social negotiations that architecture participates in the structural aspects of performativity. I will draw from concrete examples to address the local situatedness of people to one another through architectural configuration and geometry.
42.	Koch, Daniel, 1976- (författare) Digitalisering och landsbygdsutveckling : Lärdomar från Duvedmodellen för lokalsamhällen 2.0 2022 Rapport (övrigt vetenskapligt/konstnärligt)abstract Duvedprojektet för lokalsamhällen 2.0 syftar till att undersöka modeller för hur landsbygden kan utvecklas, och i viss utsträckning stå som modell för framtida samhällen i bredare perspektiv. Ett minst sagt ambitiöst, brett,och komplext mål. I det arbetet har projektets arbetsspår digitalisering konfronterats med och bearbetat en stor spännvidd av frågor, utifrån ett antal olika perspektiv. Centrala viktiga lärdomar som vuxit fram i arbetet har återkommande handlat om vikten av att kombinera det specifika i den lokala situationen med de större, bredare frågorna och processerna som såväl bidrar till, involveras i, och får sin unika och specifika form i den materiella verklighet som utgör ”det lokala”. Men också i att sådan specificitet får följdverkningar: ”resurssystem” blir inte längre abstrakta begrepp, eller generella replikerbara lösningar, utan frågor om faktiska material, människor, arbeten, processer, och så vidare.När dessa blir konkreta, visar sig också ”det lokala” vara av varierande storlek både som resultat av rådande strukturer och processer, och som resultat av vilka skalor som är relevanta för vilka frågor. Den här rapporten för en serie djupdykande resonemang för att utveckla utmaningar och möjligheter med digitalisering i en landsbygdskontext, som konsekvent sätter digitalisering i en bredare kontext för att på så sätt också föra en djupare diskussion om hur en digitaliseringsprocess kan bidra till ökad hållbarhet.
43.	Koch, Daniel, 1976-, et al. (författare) Equal living environments : Universal design and (un)equal access from a syntactic perspective, Uppsala, Sweden 2022 Ingår i: Proceedings 13th International Space Syntax Symposium. - Bergen : Western Norway University of Applied Sciences. ; , s. 466:1-26 Konferensbidrag (refereegranskat)abstract Syntactic analysis focuses analyzing space from a general perspective, where connections of ‘visibility and access’ are analyzed through different geometrical abstractions. In universal design research, the point of origin is that what is ‘visible’ or ‘accessible’ is different for different people depending on for example age or disability. This paper addresses challenges in the way models are made, used and theorized in space syntax research as capturing or describing relations between people and environment, specifically from the perspective that if people are different, so are their respective ‘connections of access and visibility’, and potentially their subsequent patterns of centrality and accessibility. Such difference, as recognized in universal design research, may appear on both the local (molecular) and the global (molar) scale; i.e., the effects of accessibility difference can be on a local scale of whether a relative detour is needed or not, but also on global structures of centrality in a city or municipality as a whole. However, there is need for structured understanding of the ‘molar’ level, and the interrelation between scales. Following Gibson’s theory that affordances exist neither in the environment nor in species, but in the specific relation between them, this paper engages with how such differences can be empirically, methodologically and theoretically understood based on empirical research in the city of Uppsala, Sweden. This work utilizes municipal data and input from disability rights organizations to explore the problem, and presents important considerations for both research and practice as comes to inclusiveness in spatial analysis and accessibility.
44.	Koch, Daniel, 1976- (författare) Narrative, dramaturgy, and spatial choreography : Movement and subjectivity in museum configurations 2024 Ingår i: Museum Configurations. - New York : Routledge. ; , s. 120-159 Bokkapitel (refereegranskat)abstract Museum architecture and curatorial exhibition designs structure the experiences and social relations associated with museum visits. Such experiences and relations are generated and qualified by movement. While patterns of movement and social relations in museums are richly studied in configurational research and museum studies respectively, qualitative aspects of movement remain to be more deeply understood – especially in relation to museum configurations. In this chapter, four museums – the Asakura Museum of Sculpture in Tokyo, Artipelag in Stockholm, Kiasma in Helsinki, and the Tokyo Metropolitan Art Museum – are put in dialogue to investigate the qualitative aspects of movement. In the investigation, movement is considered individual, collective, communicative, and performative acts, recognising the entanglement of the observer, the observed, and the participant. Working from the point of view of architecture, choreography is used to qualitatively differentiate types of movement and enrich our understanding of the role of bodies and embodiment by discussing path, figure, and gesture. This is further extended into dramaturgy by investigating rhythm, co-presence, and configurational staging. Choreographic and dramaturgical aspects are important parts of the holistic experience of the museum and exhibition narratives. Fundamental to the visitor reconstruction of museum narratives is the retrieval of synchronic configurational meaning from the sequential patterns in which museum space is initially perceived and experienced. This chapter concludes by making the case for the development of a notational language for describing and designing movement both in its local, directly perceived aspects and its emergent configurations.
45.	Koch, Daniel, 1976-, et al. (författare) Preliminär rapport: Vår Stad - hur förändrar en kris våra vanor? 2020 Rapport (populärvet., debatt m.m.)abstract Under Coronapandemin införs omfattande restriktioner och många åtgärder sätts in i syfte att förhindra smittspridning av Covid-19. Myndigheter, företag och organisationer introducerar en lång rad förändringar såsom distansarbete, distansundervisning, uppmaning om att endast göra nödvändiga resor med kollektivtrafiken men också att praktisera social distansering och självisolering. Det har resulterat i en extraordinär situation i samhället där många företag över en natt förlorat intäkter och där andra verksamheter upplever en ökad belastning, till exempel inom vården. Att begränsa rörelsemöjligheterna för så många har lett till att människor i högre utsträckning blir beroende av det som finns lokalt, blir hänvisade till det utbud och de möjligheter som erbjuds i grannskapet och i stadsdelen. Krisen har på många sätt accentuerat ojämlikheter och där människor med mindre resurser riskerar att bli utsatta och fara illa i högre utsträckning än andra. För att fånga de förändringar som vi genomlever i samhället till följd av pandemin så har en webbaserad kartenkät tagits fram där människor tillfrågas om hur deras vanor ändrats i fråga om hur staden används. Vi vill öka förståelsen för vilka platser som människor fortfarande besöker, vilka man undviker och om det eventuellt finns platser som används i högre utsträckning än tidigare. Vidare önskar vi lära oss mer om varför dessa platser besöks. Under krisen har diverse undersökningar visats som utifrån t.ex. smarta telefoner, appar eller liknande kartlägger aktiviteter och användning av platser. Syftet med web-enkäten Vår Stad är att få självrapporterade svar där det också finns mer information om vad som händer på dessa platser och varför man använder eller undviker en specifik plats. De preliminära svaren omfattar svar från en månad (25/3-27/4 2020) där Stockholm, Uppsala och Göteborg framför allt ingår.
46.	Koch, Daniel, 1976- (författare) Relative rhythms, urban oases, and spatial resilience / Exploring syntaxes of seclusion, solitude, and tranquility 2021 Ingår i: Journal of Design for Resilience in Architecture and Planning. - : Journal of Design for Resilience in Architecture & Planning. - 2757-6329. ; 2:special issue, s. 56-73 Tidskriftsartikel (refereegranskat)abstract This article engages with the role of what one might tentatively call “secondary” urban spaces, in that while they are public, they are not the most vibrant, populated, or active places. These are not the spaces envisioned in many project illustrations. They are not full of people and activity. They are however a crucial part of a wider texture of urban situations, and important to extending our understanding of seclusion, solitude, and tranquility beyond distant parks and recreation areas. My aim here is to understand the emergence of these spaces in-between; those that are close to the vibrant streets and are embedded in city centers yet which offer a respite from the most bustling urbanity. These spaces, I will argue, more easily allow for the kinds of interactions that can lead to bridging and bonding with the unknown, in addition to the important everyday encounters that occur on central streets and squares. Using qualitative methods which build on Lefebvre’s rhythmanalysis, the discussion will draw on observations of the syntactic properties that condition, enable, and characterize such spaces, and address a series of concepts, including capacity, insulation, sequencing, and interface. A better understanding of such places, it is argued, not only allows a richer set of tools for working with urban design and planning, but offers possibilities for more resilient planning in terms of generating social relations, the emergence of communities, and for cities to manage and withstand extraordinary conditions.
47.	Koch, Daniel, 1976- (författare) Systemvärld, livsvärld, och materiell värld : Implikationer och möjligheter för rumsliga analyser 2022 Ingår i: Jämlik livsmiljö. - Stockholm : Kungliga tekniska högskolan. ; , s. 97-150 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract Tillgänglighet finns inte i den fysiska miljön eller enskilda individen, utan uppstår i relationen mellan människa och miljö. Men hur ser det sambandet ut, och hur relaterar individens upplevelse av den byggda miljön till den data och de verktyg som finns inom kommunal planering och för rumsanalys? Rumsanalyser är ett viktigt verktyg som idag används för att bättre förstå hur den byggda miljön samspelar med ett antal olika faktorer, och utveckling av både teori och metod har gjort dem både mer precisa och relevanta just utifrån relationen mellan människor och miljö. Viktiga steg mot att göra analyser mer användbara ur ett universell formgivningsperspektiv har tagits inom projektet; de redovisas i studie 2, och i den här studien.Samtidigt finns kvarvarande frågor som blir viktiga när frågan ställs om förutsättningarna för olika människor ska analyseras i olika modeller. En viktig fråga är om analyser kan utgå från individers upplevelser av tillgänglighet, istället för på annat vis dokumenterade faktorer. Frågan blir viktig inte minst eftersom befintlig data inte alltid motsvarar det som behövs för att kunna svara på viktiga frågor i sammanhanget, och då insamling av sådan data kan vara väldigt omfattande. Men också eftersom den enskilda individens upplevelser bäst förstås utifrån den individen - rumsanalyser syftar till att förstå andra frågor.Genom en enkätundersökning i samarbete med Funktionsrätt Uppsala kommun har det här studerats närmare. Det framkommer såväl utmaningar som möjligheter, och viktig kunskap om hur analyser och data behöver förstås har vuxit fram. Det tar sig uttryck i begreppen ”systemvärld”, ”livsvärld” och ”materiell värld” som ett sätt att strukturera förståelsen och arbete med universell utformning som systemfråga. I den här studien fokuseras sedan på vad analyser av ”livsvärldsdata” kan säga, och frågor kring hur det kan bidra till kommunalt planeringsarbete. Det vill säga, hur rapporterade utmaningar och hinder i miljön påverkar rumsliga systemanalyser, vad vi kan lära av det, och hur det kan bidra till en dynamisk arbetsprocess i samverkan.
48.	Koch, Daniel, 1976- (författare) The Bubble, the Arrow, and the Area : Urban Design and Diagrammatic Concepts of Human Action 2021 Ingår i: The New Urban Condition. - Abingdon : Routledge. ; , s. 183-208 Bokkapitel (refereegranskat)abstract The 20th century saw significant transformations in the way cities and other settlementsw ere planned and developed; these transformations were visible not only in architecture and urban form but also in the theoretical and conceptual models, modes of operation, and challenges these fields faced. At the same time, a remarkable consistency can be observed with respect to the sorts of environments envisaged in the sometimes radically different designs, which persist even today. Central to this consistency is arguably the persistence of forms of thinking that employ diagrammatic interventions in conceptualizing psychology, subjectivity, social life, architecture, and urbanity. This chapter intends to look at three particular aspects of the move by which diagrammatic inventions have been linked to conceptualization and to review the pervasive and continued impact that such thinking has had on architecture and urban design. Whilst these impacts are not always readily apparent, they cast light on why proposals for the “no-car society” often constitute carbon copies of solutions for the car society, despite posing as its antithesis.
49.	Koch, Daniel, 1976- (författare) The smart city in the smaller context : Urbanity, data-driven planning, and AI in the context of small data and local conditions 2021 Konferensbidrag (refereegranskat)abstract The discourse on the “Smart City” and digitalization has by now grown more or less pervasive, at times posited as a given development, at times as a sought ideal, and at times as a solution. Much of this discourse tend to concern a certain kind of urbanity and subjectivity, as well as particular roles and aspects of the ICT-technology; laborers behind both the material necessities of the technology itself and of the places and products in and with which the leisurely, pleasant future is to be lived are largely absent. Similarly, code and data labor generally goes undiscussed. How digitalization best supports various lives that are structured around productive labor is also generally absent in this discourse, even though many traditionally manual labor jobs have been remarkably digitalized or at least partially automated in their own ways. Part of this is rooted in a particular understanding of the ‘urban’, as a city of (digital or physical) cosmopolitans who populate particular kinds of urban spaces in particular urban ways. This leads to narrow understanding of who a city is and should be for, what kind of city would be inclusive for others, and what kind of situations digitalization can handle. This becomes clear when approaching smaller cities or more rural conditions. Few of the most prominently suggested digital services in the “Smart City” are relevant in contexts where, for instance, there are two or three restaurants in total, which every local citizen knows well, or where who would provide—intentionally or not—the data to be used for big-data analysis or to finetune AI without severe challenges to integrity, considering the available population. This contribution aims to critically engage with some of these challenges through a project in Duved, Sweden, with about 700 inhabitants, where a digitalization project is ongoing.
50.	Koch, Max, et al. (författare) The State in the Transformation to a Sustainable Postgrowth Economy 2021. - 1 Ingår i: The Political Prospects of a Sustainability Transformation : Moving Beyond the Environmental State - Moving Beyond the Environmental State. - 9780367676711 ; , s. 115-133 Bokkapitel (refereegranskat)

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