| 1. |
- Kool, Erik C., et al.
(author)
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SN 2020bqj : A Type Ibn supernova with a long-lasting peak plateau
- 2021
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 652
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Journal article (peer-reviewed)abstract
- Context. Type Ibn supernovae (SNe Ibn) are a rare class of stripped envelope supernovae interacting with a helium-rich circumstellar medium (CSM). The majority of the SNe Ibn reported in the literature display a surprising homogeneity in their fast-evolving lightcurves and are typically found in actively starforming spiral galaxies.Aims. We present the discovery and the study of SN 2020bqj (ZTF20aalrqbu), a SN Ibn with a long-duration peak plateau lasting 40 days and hosted by a faint low-mass galaxy. We aim to explain its peculiar properties using an extensive photometric and spectroscopic data set.Methods. We compare the photometric and spectral evolution of SN 2020bqj with regular SNe Ibn from the literature, as well as with other outliers in the SN Ibn subclass. We fit the bolometric and multi-band lightcurves with powering mechanism models such as radioactive decay and CSM interaction. We also model the host galaxy of SN 2020bqj.Results. The risetime, peak magnitude and spectral features of SN 2020bqj are consistent with those of most SNe Ibn, but the SN is a clear outlier in the subclass based on its bright, long-lasting peak plateau and the low mass of its faint host galaxy. We show through modeling that the lightcurve of SN 2020bqj can be powered predominantly by shock heating from the interaction of the SN ejecta and a dense CSM, combined with radioactive decay. The peculiar Type Ibn SN 2011hw is a close analog to SN 2020bqj in terms of lightcurve and spectral evolution, suggesting a similar progenitor and CSM scenario. In this scenario a very massive progenitor star in the transitional phase between a luminous blue variable and a compact Wolf-Rayet star undergoes core-collapse, embedded in a dense helium-rich CSM with an elevated opacity compared to normal SNe Ibn, due to the presence of residual hydrogen. This scenario is consistent with the observed properties of SN 2020bqj and the modeling results.Conclusions. SN 2020bqj is a compelling example of a transitional SN Ibn/IIn based on not only its spectral features, but also its lightcurve, host galaxy properties and the inferred progenitor properties. The strong similarity with SN 2011hw suggests this subclass may be the result of a progenitor in a stellar evolution phase that is distinct from those of progenitors of regular SNe Ibn.
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| 2. |
- Abazov, V. M., et al.
(author)
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The upgraded DO detector
- 2006
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 565:2, s. 463-537
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Journal article (peer-reviewed)abstract
- The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO.
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| 5. |
- Bombarda, F., et al.
(author)
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Runaway electron beam control
- 2019
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In: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 61:1
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Journal article (peer-reviewed)
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| 14. |
- Krasilnikov, A., et al.
(author)
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Evidence of 9 Be + p nuclear reactions during 2ω CH and hydrogen minority ICRH in JET-ILW hydrogen and deuterium plasmas
- 2018
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:2
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Journal article (peer-reviewed)abstract
- The intensity of 9Be + p nuclear fusion reactions was experimentally studied during second harmonic (2ω CH) ion-cyclotron resonance heating (ICRH) and further analyzed during fundamental hydrogen minority ICRH of JET-ILW hydrogen and deuterium plasmas. In relatively low-density plasmas with a high ICRH power, a population of fast H+ ions was created and measured by neutral particle analyzers. Primary and secondary nuclear reaction products, due to 9Be + p interaction, were observed with fast ion loss detectors, γ-ray spectrometers and neutron flux monitors and spectrometers. The possibility of using 9Be(p, d)2α and 9Be(p, α)6Li nuclear reactions to create a population of fast alpha particles and study their behaviour in non-active stage of ITER operation is discussed in the paper.
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| 23. |
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| 24. |
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- 2018
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:1
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Research review (peer-reviewed)
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| 25. |
- Anand, S., et al.
(author)
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Optical follow-up of the neutron star–black hole mergers S200105ae and S200115j
- 2020
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In: Nature Astronomy. - : Nature Research. - 2397-3366.
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Journal article (peer-reviewed)abstract
- LIGO and Virgo’s third observing run revealed the first neutron star–black hole (NSBH) merger candidates in gravitational waves. These events are predicted to synthesize r-process elements1,2 creating optical/near-infrared ‘kilonova’ emission. The joint gravitational wave and electromagnetic detection of an NSBH merger could be used to constrain the equation of state of dense nuclear matter3, and independently measure the local expansion rate of the Universe4. Here, we present the optical follow-up and analysis of two of the only three high-significance NSBH merger candidates detected to date, S200105ae and S200115j, with the Zwicky Transient Facility5. The Zwicky Transient Facility observed ~48% of S200105ae and ~22% of S200115j’s localization probabilities, with observations sensitive to kilonovae brighter than −17.5 mag fading at 0.5 mag d−1 in the g- and r-bands; extensive searches and systematic follow-up of candidates did not yield a viable counterpart. We present state-of-the-art kilonova models tailored to NSBH systems that place constraints on the ejecta properties of these NSBH mergers. We show that with observed depths of apparent magnitude ~22 mag, attainable in metre-class, wide-field-of-view survey instruments, strong constraints on ejecta mass are possible, with the potential to rule out low mass ratios, high black hole spins and large neutron star radii.
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| 26. |
- Fremling, Christoffer, et al.
(author)
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Oxygen and helium in stripped-envelope supernovae
- 2018
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 618
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Journal article (peer-reviewed)abstract
- We present an analysis of 507 spectra of 173 stripped-envelope (SE) supernovae (SNe) discovered by the untargeted Palomar Transient Factory (PTF) and intermediate PTF (iPTF) surveys. Our sample contains 55 Type IIb SNe (SNe 45 Type Ib SNe (SNe IIb), 56 Type Ic SNe (SNe Ic), and 17 Type Ib/c SNe (SNe Ib/c). We have compared the SE SN subtypes via measurements of the pseudo-equivalent widths (pEWs) and velocities of the He I lambda lambda 5876, 7065 and O I lambda 7774 absorption lines. Consistent with previous work, we find that SNe Ic show higher pEWs and velocities in O I lambda 7774 compared to SNe IIb and Ib. The pEWs of the He I lambda lambda 5876, 7065 lines are similar in SNe Ib and IIb after maximum light. The He I lambda lambda 5876, 7065 velocities at maximum light are higher in SNe Ib compared to SNe IIb. We identify an anticorrelation between the He I lambda 7065 pEW and O I lambda 7774 velocity among SNe IIb and Ib. This can be interpreted as a continuum in the amount of He present at the time of explosion. It has been suggested that SNe Ib and Ic have similar amounts of He, and that lower mixing could be responsible for hiding He in SNe Ic. However, our data contradict this mixing hypothesis. The observed difference in the expansion rate of the ejecta around maximum light of SNe Ic (V-m root 2E(k)/M-ej approximate to 15 000 km s(-1)) and SNe Ib (V-m approximate to 9000 km s(-1)) would imply an average He mass difference of similar to 1.4 M-circle dot, if the other explosion parameters are assumed to be unchanged between the SE SN subtypes. We conclude that SNe Ic do not hide He but lose He due to envelope stripping.
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| 27. |
- Fremling, C., et al.
(author)
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ZTF18aalrxas : A Type IIb Supernova from a Very Extended Low-mass Progenitor
- 2019
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In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 878:1
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Journal article (peer-reviewed)abstract
- We investigate ZTF18aalrxas, a double-peaked Type IIb core-collapse supernova (SN) discovered during science validation of the Zwicky Transient Facility. ZTF18aalrxas was discovered while the optical emission was still rising toward the initial cooling peak (0.7 mag over 2 days). Our observations consist of multi-band (ultraviolet and optical) light curves (LCs), and optical spectra spanning from approximate to 0.7 to approximate to 480 days past the explosion. We use a Monte-Carlo based non-local thermodynamic equilibrium model that simultaneously reproduces both the Ni-56-powered bolometric LC and our nebular spectrum. This model is used to constrain the synthesized radioactive nickel mass (0.17 M-circle dot) and the total ejecta mass (1.7 M-circle dot) of the SN. The cooling emission is modeled using semi-analytical extended envelope models to constrain the progenitor radius (790-1050 R-circle dot) at the time of explosion. Our nebular spectrum shows signs of interaction with a dense circumstellar medium (CSM), and this spectrum is modeled and analyzed to constrain the amount of ejected oxygen (0.3-0.5 M-circle dot) and the total hydrogen mass (approximate to 0.15 M-circle dot) in the envelope of the progenitor. The oxygen mass of ZTF18aalrxas is consistent with a low (12-13 M-circle dot) zero-age main-sequence mass progenitor. The LCs and spectra of ZTF18aalrxas are not consistent with massive single-star SN Type IIb progenitor models. The presence of an extended hydrogen envelope of low mass, the presence of a dense CSM, the derived ejecta mass, and the late-time oxygen emission can all be explained in a binary model scenario.
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| 28. |
- Fynbo, J. P. U., et al.
(author)
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Low-resolution Spectroscopy of Gamma-ray Burst Optical Afterglows : Biases in the Swift Sample and Characterization of the Absorbers
- 2009
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In: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 185:2, s. 526-573
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Journal article (peer-reviewed)abstract
- We present a sample of 77 optical afterglows (OAs) of Swift detected gamma-ray bursts (GRBs) for which spectroscopic follow-up observations have been secured. Our first objective is to measure the redshifts of the bursts. For the majority (90%) of the afterglows, the redshifts have been determined from the spectra. We provide line lists and equivalent widths (EWs) for all detected lines redward of Lyα covered by the spectra. In addition to the GRB absorption systems, these lists include line strengths for a total of 33 intervening absorption systems. We discuss to what extent the current sample of Swift bursts with OA spectroscopy is a biased subsample of all Swift detected GRBs. For that purpose we define an X-ray-selected statistical sample of Swift bursts with optimal conditions for ground-based follow-up from the period 2005 March to 2008 September; 146 bursts fulfill our sample criteria. We derive the redshift distribution for the statistical (X-ray selected) sample and conclude that less than 18% of Swift bursts can be at z > 7. We compare the high-energy properties (e.g., γ-ray (15-350 keV) fluence and duration, X-ray flux, and excess absorption) for three subsamples of bursts in the statistical sample: (1) bursts with redshifts measured from OA spectroscopy; (2) bursts with detected optical and/or near-IR afterglow, but no afterglow-based redshift; and (3) bursts with no detection of the OA. The bursts in group (1) have slightly higher γ-ray fluences and higher X-ray fluxes and significantly less excess X-ray absorption than bursts in the other two groups. In addition, the fractions of dark bursts, defined as bursts with an optical to X-ray slope βOX < 0.5, is 14% in group (1), 38% in group (2), and >39% in group (3). For the full sample, the dark burst fraction is constrained to be in the range 25%-42%. From this we conclude that the sample of GRBs with OA spectroscopy is not representative for all Swift bursts, most likely due to a bias against the most dusty sight lines. This should be taken into account when determining, e.g., the redshift or metallicity distribution of GRBs and when using GRBs as a probe of star formation. Finally, we characterize GRB absorption systems as a class and compare them to QSO absorption systems, in particular the damped Lyα absorbers (DLAs). On average GRB absorbers are characterized by significantly stronger EWs for H I as well as for both low and high ionization metal lines than what is seen in intervening QSO absorbers. However, the distribution of line strengths is very broad and several GRB absorbers have lines with EWs well within the range spanned by QSO-DLAs. Based on the 33 z > 2 bursts in the sample, we place a 95% confidence upper limit of 7.5% on the mean escape fraction of ionizing photons from star-forming galaxies. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under programs 275.D-5022 (PI: Chincarini), 075.D-0270 (PI: Fynbo), 077.D-0661 (PI: Vreeswijk), 077.D-0805 (PI: Tagliaferri), 177.A-0591 (PI: Hjorth), 078.D-0416 (PI: Vreeswijk), 079.D-0429 (PI: Vreeswijk), 080.D-0526 (PI: Vreeswijk), 081.A-0135 (PI: Greiner), 281.D-5002 (PI: Della Valle), and 081.A-0856 (PI: Vreeswijk). Also based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Some of the data obtained herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck foundation.
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| 29. |
- Gal-Yam, A., et al.
(author)
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A WC/WO star exploding within an expanding carbon-oxygen-neon nebula
- 2022
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 601:7892, s. 201-204
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Journal article (peer-reviewed)abstract
- The final fate of massive stars, and the nature of the compact remnants they leave behind (black holes and neutron stars), are open questions in astrophysics. Many massive stars are stripped of their outer hydrogen envelopes as they evolve. Such Wolf-Rayet stars(1) emit strong and rapidly expanding winds with speeds greater than 1,000 kilometres per second. A fraction of this population is also helium-depleted, with spectra dominated by highly ionized emission lines of carbon and oxygen (types WC/WO). Evidence indicates that the most commonly observed supernova explosions that lack hydrogen and helium (types Ib/Ic) cannot result from massive WC/WO stars(2,3), leading some to suggest that most such stars collapse directly into black holes without a visible supernova explosion(4). Here we report observations of SN 2019hgp, beginning about a day after the explosion. Its short rise time and rapid decline place it among an emerging population of rapidly evolving transients(5-8). Spectroscopy reveals a rich set of emission lines indicating that the explosion occurred within a nebula composed of carbon, oxygen and neon. Narrow absorption features show that this material is expanding at high velocities (greater than 1,500 kilometres per second), requiring a compact progenitor. Our observations are consistent with an explosion of a massive WC/WO star, and suggest that massive Wolf-Rayet stars may be the progenitors of some rapidly evolving transients.
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| 30. |
- Miller, A. A., et al.
(author)
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The Spectacular Ultraviolet Flash from the Peculiar Type Ia Supernova 2019yvq
- 2020
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 898:1
-
Journal article (peer-reviewed)abstract
- Early observations of Type Ia supernovae (SNe Ia) provide essential clues for understanding the progenitor system that gave rise to the terminal thermonuclear explosion. We present exquisite observations of SN 2019yvq, the second observed SN Ia, after iPTF 14atg, to display an early flash of emission in the ultraviolet (UV) and optical. Our analysis finds that SN 2019yvq was unusual, even when ignoring the initial flash, in that it was moderately underluminous for an SN Ia ( mag at peak) yet featured very high absorption velocities ( km s−1 for Si ii λ6355 at peak). We find that many of the observational features of SN 2019yvq, aside from the flash, can be explained if the explosive yield of radioactive 56Ni is relatively low (we measure ) and it and other iron-group elements are concentrated in the innermost layers of the ejecta. To explain both the UV/optical flash and peak properties of SN 2019yvq we consider four different models: interaction between the SN ejecta and a nondegenerate companion, extended clumps of 56Ni in the outer ejecta, a double-detonation explosion, and the violent merger of two white dwarfs. Each of these models has shortcomings when compared to the observations; it is clear additional tuning is required to better match SN 2019yvq. In closing, we predict that the nebular spectra of SN 2019yvq will feature either H or He emission, if the ejecta collided with a companion, strong [Ca ii] emission, if it was a double detonation, or narrow [O i] emission, if it was due to a violent merger.
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| 31. |
- Ramdas, S., et al.
(author)
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A multi-layer functional genomic analysis to understand noncoding genetic variation in lipids
- 2022
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In: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 109:8, s. 1366-1387
-
Journal article (peer-reviewed)abstract
- A major challenge of genome-wide association studies (GWASs) is to translate phenotypic associations into biological insights. Here, we integrate a large GWAS on blood lipids involving 1.6 million individuals from five ancestries with a wide array of functional genomic datasets to discover regulatory mechanisms underlying lipid associations. We first prioritize lipid-associated genes with expression quantitative trait locus (eQTL) colocalizations and then add chromatin interaction data to narrow the search for functional genes. Polygenic enrichment analysis across 697 annotations from a host of tissues and cell types confirms the central role of the liver in lipid levels and highlights the selective enrichment of adipose-specific chromatin marks in high-density lipoprotein cholesterol and triglycerides. Overlapping transcription factor (TF) binding sites with lipid-associated loci identifies TFs relevant in lipid biology. In addition, we present an integrative framework to prioritize causal variants at GWAS loci, producing a comprehensive list of candidate causal genes and variants with multiple layers of functional evidence. We highlight two of the prioritized genes, CREBRF and RRBP1, which show convergent evidence across functional datasets supporting their roles in lipid biology.
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| 32. |
- Yan, Lin, et al.
(author)
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Helium-rich Superluminous Supernovae from the Zwicky Transient Facility
- 2020
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In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 902:1
-
Journal article (peer-reviewed)abstract
- Helium is expected to be present in the massive ejecta of some hydrogen-poor superluminous supernovae (SLSN-I). However, until now only one event has been identified with He features in its photospheric spectra (PTF10hgi). We present the discovery of a new He-rich SLSN-I, ZTF19aawfbtg (SN2019hge), atz = 0.0866. This event has more than 10 optical spectra at phases from -41 to +103 days relative to the peak, most of which match well with that of PTF10hgi. Confirmation comes from a near-IR spectrum taken at +34 days, revealing Heifeatures with P-Cygni profiles at 1.083 and 2.058 mu m. Using the optical spectra of PTF10hgi and SN2019hge as templates, we examined 70 other SLSNe-I discovered by Zwicky Transient Facility in the first two years of operation and found five additional SLSNe-I with distinct He-features. The excitation of Heiatoms in normal core-collapse supernovae requires nonthermal radiation, as proposed by previous studies. These He-rich events cannot be explained by the traditional(56)Ni mixing model because of their blue spectra, high peak luminosities, and long rise timescales. Magnetar models offer a possible solution since pulsar winds naturally generate high-energy particles, potential sources of nonthermal excitation. An alternative model is the interaction between the ejecta and dense H-poor circumstellar material, which may be supported by observed undulations in the light curves. These six SLSNe-Ib have relatively low-peak luminosities (rest frameM(g) = -20.06 0.16).
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| 33. |
- Yan, Lin, et al.
(author)
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Hydrogen-poor Superluminous Supernovae with Late-time H alpha Emission : Three Events From the Intermediate Palomar Transient Factory
- 2017
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 848:1
-
Journal article (peer-reviewed)abstract
- We present observations of two new hydrogen-poor superluminous supernovae (SLSN-I), iPTF15esb and iPTF16bad, showing late-time H alpha emission with line luminosities of (1-3) x 10(41) erg s(-1) and velocity widths of (4000-6000) km s(-1). Including the previously published iPTF13ehe, this makes up a total of three such events to date. iPTF13ehe is one of the most luminous and the slowest evolving SLSNe-I, whereas the other two are less luminous and fast decliners. We interpret this as a result of the ejecta running into a neutral H-shell located at a radius of similar to 10(16) cm. This implies that violent mass loss must have occurred several decades before the supernova explosion. Such a short time interval suggests that eruptive mass loss could be common shortly before core collapse, and more importantly helium is unlikely to be completely stripped off the progenitor and could be present in the ejecta. It is a mystery why helium features are not detected, even though nonthermal energy sources, capable of ionizing He, may exist as suggested by the O II absorption series in the early-time spectra. Our late-time spectra (+240 days) appear to have intrinsically lower [O I] 6300 angstrom luminosities than that of SN2015bn and SN2007bi, which is possibly an indication of less oxygen (<10 M-circle dot). The blueshifted H alpha emission relative to the hosts for all three events may be in tension with the binary model proposed for iPTF13ehe. Finally, iPTF15esb has a peculiar light curve (LC) with three peaks separated from one another by similar to 22 days. The LC undulation is stronger in bluer bands. One possible explanation is ejecta-circumstellar medium interaction.
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| 34. |
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| 35. |
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| 36. |
- Fremling, C., et al.
(author)
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The Zwicky Transient Facility Bright Transient Survey. I. Spectroscopic Classification and the Redshift Completeness of Local Galaxy Catalogs
- 2020
-
In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 895:1
-
Journal article (peer-reviewed)abstract
- The Zwicky Transient Facility (ZTF) is performing a three-day cadence survey of the visible northern sky (similar to 3 pi) with newly found transient candidates announced via public alerts. The ZTF Bright Transient Survey (BTS) is a large spectroscopic campaign to complement the photometric survey. BTS endeavors to spectroscopically classify all extragalactic transients with m(peak) <= 18.5 mag in either the g(ZTF) or r(ZTF) filters, and publicly announce said classifications. BTS discoveries are predominantly supernovae (SNe), making this the largest flux-limited SN survey to date. Here we present a catalog of 761 SNe, classified during the first nine months of ZTF (2018 April 1-2018 December 31). We report BTS SN redshifts from SN template matching and spectroscopic host-galaxy redshifts when available. We analyze the redshift completeness of local galaxy catalogs, the redshift completeness fraction (RCF; the ratio of SN host galaxies with known spectroscopic redshift prior to SN discovery to the total number of SN hosts). Of the 512 host galaxies with SNe Ia, 227 had previously known spectroscopic redshifts, yielding an RCF estimate of 44% 4%. The RCF decreases with increasing distance and decreasing galaxy luminosity (for z < 0.05, or similar to 200 Mpc, RCF 0.6). Prospects for dramatically increasing the RCF are limited to new multifiber spectroscopic instruments or wide-field narrowband surveys. Existing galaxy redshift catalogs are only similar to 50% complete at r 16.9 mag. Pushing this limit several magnitudes deeper will pay huge dividends when searching for electromagnetic counterparts to gravitational wave events or sources of ultra-high-energy cosmic rays or neutrinos.
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| 37. |
-
Overview of the JET results
- 2015
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In: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 55:10
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Journal article (peer-reviewed)
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| 38. |
- Pennells, Lisa, et al.
(author)
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Equalization of four cardiovascular risk algorithms after systematic recalibration : individual-participant meta-analysis of 86 prospective studies
- 2019
-
In: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 40:7, s. 621-
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Journal article (peer-reviewed)abstract
- Aims: There is debate about the optimum algorithm for cardiovascular disease (CVD) risk estimation. We conducted head-to-head comparisons of four algorithms recommended by primary prevention guidelines, before and after ‘recalibration’, a method that adapts risk algorithms to take account of differences in the risk characteristics of the populations being studied.Methods and results: Using individual-participant data on 360 737 participants without CVD at baseline in 86 prospective studies from 22 countries, we compared the Framingham risk score (FRS), Systematic COronary Risk Evaluation (SCORE), pooled cohort equations (PCE), and Reynolds risk score (RRS). We calculated measures of risk discrimination and calibration, and modelled clinical implications of initiating statin therapy in people judged to be at ‘high’ 10 year CVD risk. Original risk algorithms were recalibrated using the risk factor profile and CVD incidence of target populations. The four algorithms had similar risk discrimination. Before recalibration, FRS, SCORE, and PCE over-predicted CVD risk on average by 10%, 52%, and 41%, respectively, whereas RRS under-predicted by 10%. Original versions of algorithms classified 29–39% of individuals aged ≥40 years as high risk. By contrast, recalibration reduced this proportion to 22–24% for every algorithm. We estimated that to prevent one CVD event, it would be necessary to initiate statin therapy in 44–51 such individuals using original algorithms, in contrast to 37–39 individuals with recalibrated algorithms.Conclusion: Before recalibration, the clinical performance of four widely used CVD risk algorithms varied substantially. By contrast, simple recalibration nearly equalized their performance and improved modelled targeting of preventive action to clinical need.
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| 39. |
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- 2019
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Journal article (peer-reviewed)
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| 40. |
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- 2018
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:9
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Journal article (peer-reviewed)
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| 41. |
- Adam, J., et al.
(author)
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Centrality dependence of high-p(T) D meson suppression in Pb-Pb collisions at root s(NN)=2.76 TeV
- 2015
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In: Journal of High Energy Physics. - 1029-8479. ; :11
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Journal article (peer-reviewed)abstract
- The nuclear modification factor, R-AA, of the prompt charmed mesons D-0, D+ and D*+, and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at a centre-of-mass energy root s(NN) = 2 : 76 TeV in two transverse momentum intervals, 5 < p(T) < 8 GeV/c and 8 < p(T) < 16 GeV/c, and in six collision centrality classes. The R-AA shows a maximum suppression of a factor of 5{6 in the 10% most central collisions. The suppression and its centrality dependence are compatible within uncertainties with those of charged pions. A comparison with the R-AA of non-prompt J/psi from B meson decays, measured by the CMS Collaboration, hints at a larger suppression of D mesons in the most central collisions.
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| 42. |
- Adam, J., et al.
(author)
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Centrality dependence of inclusive J/psi production in p-Pb collisions at root S-NN=5.02TeV
- 2015
-
In: Journal of High Energy Physics. - 1029-8479. ; :11
-
Journal article (peer-reviewed)abstract
- We present a measurement of inclusive J/psi production in p-Pb collisions at root S-NN = 5.02 TeV as a function of the centrality of the collision, as estimated from the energy deposited in the Zero Degree Calorimeters. The measurement is performed with the ALICE detector down to zero transverse momentum, p(T), in the backward (-4.46 < y(cms) < -2.96) and forward (2.03 < y(cms) < 3.53) rapidity intervals in the dimuon decay channel and in the mid-rapidity region (-1.37 < y(cms) < 0.43) in the dielectron decay channel. The backward and forward rapidity intervals correspond to the Pb-going and p-going direction, respectively. The p(T)-differential J/psi production cross section at backward and forward rapidity is measured for several centrality classes, together with the corresponding average p(T) and p(T)(2) values. The nuclear modification factor is presented as a function of centrality for the three rapidity intervals, and as a function of p(T) for several centrality classes at backward and forward rapidity. At mid-and forward rapidity, the J/psi yield is suppressed up to 40% compared to that in pp interactions scaled by the number of binary collisions. The degree of suppression increases towards central p-Pb collisions at forward rapidity, and with decreasing p(T) of the J/psi. At backward rapidity, the nuclear modification factor is compatible with unity within the total uncertainties, with an increasing trend from peripheral to central p-Pb collisions.
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| 43. |
- Adam, J., et al.
(author)
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Inclusive, prompt and non-prompt J/psi production at mid-rapidity in Pb-Pb collisions at root S-NN=2.76 TeV
- 2015
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In: Journal of High Energy Physics. - 1029-8479. ; :7
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Journal article (peer-reviewed)abstract
- The transverse momentum (p(T)) dependence of the nuclear modification factor R-AA and the centrality dependence of the average transverse momentum for inclusive J/psi have been measured with ALICE for Pb-Pb collisions at root S-NN = 2.76TeV in the e(+)e(-) decay channel at mid-rapidity (vertical bar y vertical bar < 0.8). The is significantly smaller than the one observed for pp collisions at the same centre-of-mass energy. Consistently, an increase of RAA is observed towards low p(T). These observations might be indicative of a sizable contribution of charm quark coalescence to the J/psi production. Additionally, the fraction of non-prompt J/psi from beauty hadron decays, f(B), has been determined in the region 1.5 < p(T) < 10 GeV/c in three centrality intervals. No significant centrality dependence of fB is observed. Finally, the RAA of non-prompt J/psi is discussed and compared with model predictions. The nuclear modification in the region 4.5 < p(T) < 10 GeV/c is found to be stronger than predicted by most models.
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| 44. |
- Adam, J., et al.
(author)
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Measurement of jet quenching with semi-inclusive hadron-jet distributions in central Pb-Pb collisions at root s(NN)=2.76 TeV
- 2015
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In: Journal of High Energy Physics. - 1029-8479. ; :9
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Journal article (peer-reviewed)abstract
- We report the measurement of a new observable of jet quenching in central Pb-Pb collisions at root s(NN) = 2.76 TeV, based on the semi-inclusive rate of charged jets recoiling from a high transverse momentum (high-p T) charged hadron trigger. Jets are measured using collinear-safe jet reconstruction with infrared cutoff for jet constituents of 0.15 GeV, for jet resolution parameters R = 0.2, 0.4 and 0.5. Underlying event background is corrected at the event-ensemble level, without imposing bias on the jet population. Recoil jet spectra are reported in the range 20 < p(T,jet)(ch) < 100 GeV. Reference distributions for pp collisions at root s = 2.76TeV are calculated using Monte Carlo and NLO pQCD methods, which are validated by comparing with measurements in pp collisions at root s = 7TeV. The recoil jet yield in central Pb-Pb collisions is found to be suppressed relative to that in pp collisions. No significant medium-induced broadening of the intra-jet energy profile is observed within 0.5 radians relative to the recoil jet axis. The angular distribution of the recoil jet yield relative to the trigger axis is found to be similar in central Pb-Pb and pp collisions, with no significant medium-induced acoplanarity observed. Large-angle jet deflection, which may provide a direct probe of the nature of the quasi-particles in hot QCD matter, is explored.
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| 45. |
- Adam, J., et al.
(author)
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One-dimensional pion, kaon, and proton femtoscopy in Pb-Pb collisions at root(NN)-N-S=2.76 TeV
- 2015
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 92:5
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Journal article (peer-reviewed)abstract
- The size of the particle emission region in high-energy collisions can be deduced using the femtoscopic correlations of particle pairs at low relative momentum. Such correlations arise due to quantum statistics and Coulomb and strong final state interactions. In this paper, results are presented from femtoscopic analyses of pi(+/-) pi(+/-), K-+/- K-+/-, K-S(0) K-S(0), pp, and (pp) over bar correlations from Pb-Pb collisions at root s(NN) = 2.76 TeV by the ALICE experiment at the LHC. One-dimensional radii of the system are extracted from correlation functions in terms of the invariant momentum difference of the pair. The comparison of the measured radii with the predictions from a hydrokinetic model is discussed. The pion and kaon source radii display a monotonic decrease with increasing average pair transverse mass m(T) which is consistent with hydrodynamic model predictions for central collisions. The kaon and proton source sizes can be reasonably described by approximate m(T) scaling.
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| 46. |
- Ahumada, T., et al.
(author)
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Discovery and confirmation of the shortest gamma-ray burst from a collapsar
- 2021
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In: Nature Astronomy. - : Springer Nature. - 2397-3366. ; 5:9, s. 917-927
-
Journal article (peer-reviewed)abstract
- Gamma-ray bursts (GRBs) are among the brightest and most energetic events in the Universe. The duration and hardness distribution of GRBs has two clusters1, now understood to reflect (at least) two different progenitors2. Short-hard GRBs (SGRBs; T90 < 2 s) arise from compact binary mergers, and long-soft GRBs (LGRBs; T90 > 2 s) have been attributed to the collapse of peculiar massive stars (collapsars)3. The discovery of SN 1998bw/GRB 980425 (ref. 4) marked the first association of an LGRB with a collapsar, and AT 2017gfo (ref. 5)/GRB 170817A/GW170817 (ref. 6) marked the first association of an SGRB with a binary neutron star merger, which also produced a gravitational wave. Here, we present the discovery of ZTF20abwysqy (AT2020scz), a fast-fading optical transient in the Fermi satellite and the Interplanetary Network localization regions of GRB 200826A; X-ray and radio emission further confirm that this is the afterglow. Follow-up imaging (at rest-frame 16.5 days) reveals excess emission above the afterglow that cannot be explained as an underlying kilonova, but which is consistent with being the supernova. Although the GRB duration is short (rest-frame T90 of 0.65 s), our panchromatic follow-up data confirm a collapsar origin. GRB 200826A is the shortest LGRB found with an associated collapsar; it appears to sit on the brink between a successful and a failed collapsar. Our discovery is consistent with the hypothesis that most collapsars fail to produce ultra-relativistic jets.
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| 47. |
- Alberdi, A., et al.
(author)
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The high-frequency compact radio structure of the peculiar quasar 4C 39.25
- 1997
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In: Astronomy and Astrophysics. - : Springer-Verlag. - 0004-6361 .- 1432-0746. ; 327:2, s. 513-521
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Journal article (peer-reviewed)abstract
- We present new high angular resolution images of the compact non-thermal radio source 4C 39.25 obtained from VLBI observations at λ1.3cm, λ7mm, and λ3mm wavelengths. These maps and Gaussian model-fits show that the milli-arcsecond to sub-milliarcsecond structure of 4C 39.25 consists of a complex bent core-jet structure with embedded moving and stationary VLBI components. Facilitated by the small observing beams and high angular resolutions obtained at mm-wavelengths, we measured the relative positions of the jet components with an accuracy of a few hundred micro-arcseconds. This allows the detailed followup of the ongoing merging process of a westward superluminally moving component (b_) with a stationary component a_, located at ~2.9 mas east of the putative core d_. In contrast to the other components of the structure with steeper spectra, the westernmost component d_ exhibits an inverted spectrum peaking between λ7mm and λ3mm, thus further supporting its identification as the VLBI core, self-absorbed at longer wavelengths. From two VLBI maps obtained nearly simultaneously at λ7mm and λ1.3cm, we made the first spectral index map of 4C 39.25 in this wavelength regime. The main characteristics of the spectral index distribution of the jet are pronounced changes of the spectral index between orientations parallel and transverse to the jet axis. Near the merging components a_ and b_ the spectral index steepens with increasing separation from d_. However, in the bridge of emission c_, which connects d_ with a_ and b_, the spectral index gradient has a direction transverse to the jet axis, suggesting a frequency dependent jet curvature and edge-brightening. A brief discussion of this behaviour within current jet models is presented.
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| 48. |
- Chen, Z. H., et al.
(author)
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The Hydrogen-poor Superluminous Supernovae from the Zwicky Transient Facility Phase I Survey. I. Light Curves and Measurements
- 2023
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 943:1
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Journal article (peer-reviewed)abstract
- During the Zwicky Transient Facility (ZTF) Phase I operations, 78 hydrogen-poor superluminous supernovae (SLSNe-I) were discovered in less than 3 yr, constituting the largest sample from a single survey. This paper (Paper I) presents the data, including the optical/UV light curves and classification spectra, while Paper II in this series will focus on the detailed analysis of the light curves and modeling. Our photometry is primarily taken by ZTF in the g, r, and i bands, and with additional data from other ground-based facilities and Swift. The events of our sample cover a redshift range of z = 0.06 − 0.67, with a median and 1σ error (16% and 84% percentiles) of zmed=0.265. The peak luminosity covers −22.8 mag ≤ Mg,peak ≤ −19.8 mag, with a median value of -21.48. The light curves evolve slowly with a mean rest-frame rise time of trise = 41.9 ± 17.8 days. The luminosity and timescale distributions suggest that low-luminosity SLSNe-I with a peak luminosity ∼−20 mag or extremely fast-rising events (<10 days) exist, but are rare. We confirm previous findings that slowly rising SLSNe-I also tend to fade slowly. The rest-frame color and temperature evolution show large scatters, suggesting that the SLSN-I population may have diverse spectral energy distributions. The peak rest-frame color shows a moderate correlation with the peak absolute magnitude, i.e., brighter SLSNe-I tend to have bluer colors. With optical and UV photometry, we construct the bolometric luminosity and derive a bolometric correction relation that is generally applicable for converting g, r-band photometry to the bolometric luminosity for SLSNe-I.
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| 49. |
- Chen, Z. H., et al.
(author)
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The Hydrogen-poor Superluminous Supernovae from the Zwicky Transient Facility Phase I Survey. II. Light-curve Modeling and Characterization of Undulations
- 2023
-
In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 943:1, s. 42-
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Journal article (peer-reviewed)abstract
- We present analysis of the light curves (LCs) of 77 hydrogen-poor superluminous supernovae (SLSNe I) discovered during the Zwicky Transient Facility Phase I operation. We find that the majority (67%) of the sample can be fit equally well by both magnetar and ejecta-circumstellar medium (CSM) interaction plus 56Ni decay models. This implies that LCs alone cannot unambiguously constrain the physical power sources for an SLSN I. However, 23% of the sample show inverted V-shape, steep-declining LCs or features of long rise and fast post-peak decay, which are better described by the CSM+Ni model. The remaining 10% of the sample favors the magnetar model. Moreover, our analysis shows that the LC undulations are quite common, with a fraction of 18%-44% in our gold sample. Among those strongly undulating events, about 62% of them are found to be CSM-favored, implying that the undulations tend to occur in the CSM-favored events. Undulations show a wide range in energy and duration, with median values (and 1σ errors) being as 1.7 % − 0.7 % + 1.5 % E rad , total and 28.8 − 9.1 + 14.4 days, respectively. Our analysis of the undulation timescales suggests that intrinsic temporal variations of the central engine can explain half of the undulating events, while CSM interaction (CSI) can account for the majority of the sample. Finally, all of the well-observed He-rich SLSNe Ib either have strongly undulating LCs or the LCs are much better fit by the CSM+Ni model. These observations imply that their progenitor stars have not had enough time to lose all of the He-envelopes before supernova explosions, and H-poor CSM are likely to present in these events.
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| 50. |
- Childress, M. J., et al.
(author)
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Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra
- 2015
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In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 454:4, s. 3816-3842
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Journal article (peer-reviewed)abstract
- The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of Ni-56 to Co-56 at early times, and the decay of Co-56 to Fe-56 from similar to 60 d after explosion. We examine the evolution of the [Co III] lambda 5893 emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of Co-56 as a function of time. This result indicates both efficient local energy deposition from positrons produced in Co-56 decay and long-term stability of the ionization state of the nebula. We compile SN Ia nebular spectra from the literature and present 21 new late-phase spectra of 7 SNe Ia, including SN 2014J. From these we measure the flux in the [Co III] lambda 5893 line and remove its well-behaved time dependence to infer the initial mass of Ni-56 (M-Ni, produced in the explosion. We then examine Ni-56 yields for different SN Ia ejected masses (M-ej-calculated using the relation between light-curve width and ejected mass) and find that the Ni-56 masses of SNe Ia fall into two regimes: for narrow light curves (low stretch s similar to 0.7-0.9), M-Ni is clustered near MN, 0.4 Me and shows a shallow increase as Mei increases from similar to 1 to 1.4 M-circle dot; at high stretch, M-ej clusters at the Chandrasekhar mass (1.4 M-circle dot) while M-Ni, spans a broad range from 0.6 to 1.2 M-circle dot. This could constitute evidence for two distinct SN Ia explosion mechanisms.
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