| 1. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- de Jong, R. S., et al.
(författare)
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4MOST : Project overview and information for the First Call for Proposals
- 2019
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Ingår i: The Messenger. - : European Southern Observatory. - 0722-6691. ; 175, s. 3-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations.
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| 7. |
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| 8. |
- Aguilar, J. A., et al.
(författare)
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Triboelectric backgrounds to radio-based polar ultra-high energy neutrino (UHEN) experiments
- 2023
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Ingår i: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 145
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Tidskriftsartikel (refereegranskat)abstract
- In the hopes of observing the highest-energy neutrinos (E> 1 EeV) populating the Universe, both past (RICE, AURA, ANITA) and current (RNO-G, ARIANNA, ARA and TAROGE-M) polar-sited experiments exploit the impulsive radio emission produced by neutrino interactions. In such experiments, rare single event candidates must be unambiguously identified above backgrounds. Background rejection strategies to date primarily target thermal noise fluctuations and also impulsive radio-frequency signals of anthropogenic origin. In this paper, we consider the possibility that 'fake' neutrino signals may also be generated naturally via the `triboelectric effect' This broadly describes any process in which force applied at a boundary layer results in displacement of surface charge, leading to the production of an electrostatic potential difference AV. Wind blowing over granular surfaces such as snow can induce such a potential difference, with subsequent coronal discharge. Discharges over timescales as short as nanoseconds can then lead to radio-frequency emissions at characteristic MHz-GHz frequencies. Using data from various past (RICE, AURA, SATRA, ANITA) and current (RNO G, ARIANNA and ARA) neutrino experiments, we find evidence for such backgrounds, which are generally characterized by: (a) a threshold wind velocity which likely depends on the experimental trigger criteria and layout; for the experiments considered herein, this value is typically O(10 m/s), (b) frequency spectra generally shifted to the low-end of the frequency regime to which current radio experiments are typically sensitive (100-200 MHz), (c) for the strongest background signals, an apparent preference for discharges from above-surface structures, although the presence of more isotropic, lower amplitude triboelectric discharges cannot be excluded.
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| 9. |
- Blanton, Michael R., et al.
(författare)
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Sloan Digital Sky Survey IV : Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
- 2017
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Ingår i: Astronomical Journal. - : IOP Publishing Ltd. - 0004-6256 .- 1538-3881. ; 154:1
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Tidskriftsartikel (refereegranskat)abstract
- We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and. high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z similar to 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z similar to 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs. and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the. Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.
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| 10. |
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| 11. |
- Abolfathi, Bela, et al.
(författare)
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The Fourteenth Data Release of the Sloan Digital Sky Survey : First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment
- 2018
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Ingår i: Astrophysical Journal Supplement Series. - : IOP Publishing Ltd. - 0067-0049 .- 1538-4365. ; 235:2
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Tidskriftsartikel (refereegranskat)abstract
- The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since 2014 July. This paper describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14). This release makes the data taken by SDSS-IV in its first two years of operation (2014-2016 July) public. Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey; the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data-driven machine-learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from the SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS web site (www.sdss.org) has been updated for this release and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020 and will be followed by SDSS-V.
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| 12. |
- Betoule, M., et al.
(författare)
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Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 568, s. A22-
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We present cosmological constraints from a joint analysis of type la supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The dataset includes several low-redshift samples (z < 0.1), all three seasons from the SDSS-11 (0.05 < z < 0.4), and three years from SNLS (0.2 < z < 1), and it totals 740 spectroscopically confirmed type la supernovae with high quality light curves. Methods. We followed the methods and assumptions of the SNLS three-year data analysis except for the following important improvements: I) the addition of the full SDSS-II spectroscopically-confirmed SN la sample in both the training of the SALT2 light-curve model and in the Hubble diagram analysis (374 SNe); 2) intercalibration of the SNLS and SDSS surveys and reduced systematic uncertainties in the photometric calibration, performed blindly with respect to the cosmology analysis; and 3) a thorough investigation of systematic errors associated with the SALT2 modeling of SN la light curves. Results. We produce recalibrated SN la light curves and associated distances for the SDSS-II and SNLS samples. The large SOSS-II sample provides an effective, independent, low -z anchor for the Hubble diagram and reduces the systematic error from calibration systematics in the low -z SN sample. For a flat ACDM cosmology, we find Omega(m), = 0.295 0.034 (stat+sys), a value consistent with the most recent cosmic microwave background (CMB) measurement from the Planck and WMAP experiments. Our result is 1.8 sigma (stat+sys) different than the previously published result of SNLS three-year data. The change is due primarily to improvements in the SNLS photometric calibration. When combined with CMB constraints, we measure a constant dark energy equation of state parameter omega = -1.018 +/- 0,057 (sral+sys) for a fiat universe. Adding baryon acoustic oscillation distance measurements gives similar constraints: omega = 59 -1.027 0.055. Our supernova measurements provide the most stringent constraints to date on the nature of dark energy.
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| 13. |
- Zhang, Y., et al.
(författare)
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Galaxies in X-ray selected clusters and groups in Dark Energy Survey data - II. Hierarchical Bayesian modelling of the red-sequence galaxy luminosity function
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 488:1, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- Using similar to 100 X-ray selected clusters in the Dark Energy Survey Science Verification data, we constrain the luminosity function ( LF) of cluster red-sequence galaxies as a function of redshift. This is the first homogeneous optical/X-ray sample large enough to constrain the evolution of the LF simultaneously in redshift ( 0.1 < z < 1.05) and cluster mass ( 13.5 <= log(10)( M-200crit) similar to< 15.0). We pay particular attention to completeness issues and the detection limit of the galaxy sample. We then apply a hierarchical Bayesian model to fit the cluster galaxy LFs via a Schechter function, including its characteristic break ( m*) to a faint end power-law slope ( alpha). Our method enables us to avoid known issues in similar analyses based on stacking or binning the clusters. We find weak and statistically insignificant (similar to 1.9 sigma) evolution in the faint end slope alpha versus redshift. We also find no dependence in alpha or m* with the X-ray inferred cluster masses. However, the amplitude of the LF as a function of cluster mass is constrained to similar to 20 per cent precision. As a by-product of our algorithm, we utilize the correlation between the LF and cluster mass to provide an improved estimate of the individual cluster masses as well as the scatter in true mass given the X-ray inferred masses. This technique can be applied to a larger sample of X-ray or optically selected clusters from the Dark Energy Survey, significantly improving the sensitivity of the analysis.
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| 14. |
- Kousathanas, A, et al.
(författare)
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Whole-genome sequencing reveals host factors underlying critical COVID-19
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 607:7917, s. 97-
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Tidskriftsartikel (refereegranskat)abstract
- Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2–4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease.
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| 15. |
- Axfors, Cathrine, et al.
(författare)
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Association between convalescent plasma treatment and mortality in COVID-19 : a collaborative systematic review and meta-analysis of randomized clinical trials
- 2021
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Ingår i: BMC Infectious Diseases. - : BioMed Central (BMC). - 1471-2334. ; 21:1
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Forskningsöversikt (refereegranskat)abstract
- Background: Convalescent plasma has been widely used to treat COVID-19 and is under investigation in numerous randomized clinical trials, but results are publicly available only for a small number of trials. The objective of this study was to assess the benefits of convalescent plasma treatment compared to placebo or no treatment and all-cause mortality in patients with COVID-19, using data from all available randomized clinical trials, including unpublished and ongoing trials (Open Science Framework, ). Methods: In this collaborative systematic review and meta-analysis, clinical trial registries (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform), the Cochrane COVID-19 register, the LOVE database, and PubMed were searched until April 8, 2021. Investigators of trials registered by March 1, 2021, without published results were contacted via email. Eligible were ongoing, discontinued and completed randomized clinical trials that compared convalescent plasma with placebo or no treatment in COVID-19 patients, regardless of setting or treatment schedule. Aggregated mortality data were extracted from publications or provided by investigators of unpublished trials and combined using the Hartung-Knapp-Sidik-Jonkman random effects model. We investigated the contribution of unpublished trials to the overall evidence. Results: A total of 16,477 patients were included in 33 trials (20 unpublished with 3190 patients, 13 published with 13,287 patients). 32 trials enrolled only hospitalized patients (including 3 with only intensive care unit patients). Risk of bias was low for 29/33 trials. Of 8495 patients who received convalescent plasma, 1997 died (23%), and of 7982 control patients, 1952 died (24%). The combined risk ratio for all-cause mortality was 0.97 (95% confidence interval: 0.92; 1.02) with between-study heterogeneity not beyond chance (I-2 = 0%). The RECOVERY trial had 69.8% and the unpublished evidence 25.3% of the weight in the meta-analysis. Conclusions: Convalescent plasma treatment of patients with COVID-19 did not reduce all-cause mortality. These results provide strong evidence that convalescent plasma treatment for patients with COVID-19 should not be used outside of randomized trials. Evidence synthesis from collaborations among trial investigators can inform both evidence generation and evidence application in patient care.
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| 16. |
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| 17. |
- Mehrtens, N., et al.
(författare)
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The XMM Cluster Survey : the halo occupation number of BOSS galaxies in X-ray clusters
- 2016
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 463:2, s. 1929-1943
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Tidskriftsartikel (refereegranskat)abstract
- We present a direct measurement of the mean halo occupation distribution (HOD) of galaxies taken from the eleventh data release (DR11) of the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey (BOSS). The HOD of BOSS low-redshift (LOWZ: 0.2 < z < 0.4) and Constant-Mass (CMASS: 0.43 < z < 0.7) galaxies is inferred via their association with the dark matter haloes of 174 X-ray-selected galaxy clusters drawn from the XMM Cluster Survey (XCS). Halo masses are determined for each galaxy cluster based on X-ray temperature measurements, and range between log10(M180/M⊙) = 13 and 15. Our directly measured HODs are consistent with the HOD-model fits inferred via the galaxy-clustering analyses of Parejko et al. for the BOSS LOWZ sample and White et al. for the BOSS CMASS sample. Under the simplifying assumption that the other parameters that describe the HOD hold the values measured by these authors, we have determined a best-fitting alpha-index of 0.91 ± 0.08 and 1.27−0.04+0.03" role="presentation">1.27+0.03−0.04 for the CMASS and LOWZ HOD, respectively. These alpha-index values are consistent with those measured by White et al. and Parejko et al. In summary, our study provides independent support for the HOD models assumed during the development of the BOSS mock-galaxy catalogues that have subsequently been used to derive BOSS cosmological constraints.
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| 18. |
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| 19. |
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| 20. |
- Mehrtens, Nicola, et al.
(författare)
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The XMM Cluster Survey : optical analysis methodology and the first data release
- 2012
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 423:2, s. 1024-1052
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Tidskriftsartikel (refereegranskat)abstract
- The XMM Cluster Survey (XCS) is a serendipitous search for galaxy clusters using all publicly available data in the XMMNewton Science Archive. Its main aims are to measure cosmological parameters and trace the evolution of X-ray scaling relations. In this paper we present the first data release from the XMM Cluster Survey (XCS-DR1). This consists of 503 optically confirmed, serendipitously detected, X-ray clusters. Of these clusters, 256 are new to the literature and 357 are new X-ray discoveries. We present 463 clusters with a redshift estimate (0.06 < z < 1.46), including 261 clusters with spectroscopic redshifts. The remainder have photometric redshifts. In addition, we have measured X-ray temperatures (TX) for 401 clusters (0.4 < TX < 14.7 keV). We highlight seven interesting subsamples of XCS-DR1 clusters: (i) 10 clusters at high redshift (z > 1.0, including a new spectroscopically confirmed cluster at z= 1.01); (ii) 66 clusters with high TX (>5 keV); (iii) 130 clusters/groups with low TX (<2 keV); (iv) 27 clusters with measured TX values in the Sloan Digital Sky Survey (SDSS) Stripe 82 co-add region; (v) 77 clusters with measured TX values in the Dark Energy Survey region; (vi) 40 clusters detected with sufficient counts to permit mass measurements (under the assumption of hydrostatic equilibrium); (vii) 104 clusters that can be used for applications such as the derivation of cosmological parameters and the measurement of cluster scaling relations. The X-ray analysis methodology used to construct and analyse the XCS-DR1 cluster sample has been presented in a companion paper, Lloyd-Davies et al.
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| 21. |
- Prentice, S. J., et al.
(författare)
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SN 2018gjx reveals that some SNe Ibn are SNe IIb exploding in dense circumstellar material
- 2020
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 499:1, s. 1450-1467
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Tidskriftsartikel (refereegranskat)abstract
- We present the data and analysis of SN 2018gjx, an unusual low-luminosity transient with three distinct spectroscopic phases. Phase I shows a hot blue spectrum with signatures of ionized circumstellar material (CSM), Phase II has the appearance of broad SN features, consistent with those seen in a Type IIb supernova at maximum light, and Phase III is that of a supernova interacting with helium-rich CSM, similar to a Type Ibn supernova. This event provides an apparently rare opportunity to view the inner workings of an interacting supernova. The observed properties can be explained by the explosion of a star in an aspherical CSM. The initial light is emitted from an extended CSM (similar to 4000 R-circle dot), which ionizes the exterior unshocked material. Some days after, the SN photosphere envelops this region, leading to the appearance of a SN IIb. Over time, the photosphere recedes in velocity space, revealing interaction between the supernova ejecta and the CSM that partially obscures the supernova nebular phase. Modelling of the initial spectrum reveals a surface composition consistent with compact H-deficient Wolf-Rayet and Luminous Blue Variable (LBV) stars. Such configurations may not be unusual, with SNe IIb being known to have signs of interaction so at least some SNe IIb and SNe Ibn may be the same phenomena viewed from different angles, or possibly with differing CSM configurations.
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| 22. |
- Dankiewicz, Josef, et al.
(författare)
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Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest
- 2021
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Ingår i: New England Journal of Medicine. - : MASSACHUSETTS MEDICAL SOC. - 0028-4793 .- 1533-4406. ; 384:24, s. 2283-2294
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Tidskriftsartikel (refereegranskat)abstract
- Hypothermia or Normothermia after Cardiac Arrest This trial randomly assigned patients with coma after out-of-hospital cardiac arrest to undergo targeted hypothermia at 33 degrees C or normothermia with treatment of fever. At 6 months, there were no significant between-group differences regarding death or functional outcomes. Background Targeted temperature management is recommended for patients after cardiac arrest, but the supporting evidence is of low certainty. Methods In an open-label trial with blinded assessment of outcomes, we randomly assigned 1900 adults with coma who had had an out-of-hospital cardiac arrest of presumed cardiac or unknown cause to undergo targeted hypothermia at 33 degrees C, followed by controlled rewarming, or targeted normothermia with early treatment of fever (body temperature, >= 37.8 degrees C). The primary outcome was death from any cause at 6 months. Secondary outcomes included functional outcome at 6 months as assessed with the modified Rankin scale. Prespecified subgroups were defined according to sex, age, initial cardiac rhythm, time to return of spontaneous circulation, and presence or absence of shock on admission. Prespecified adverse events were pneumonia, sepsis, bleeding, arrhythmia resulting in hemodynamic compromise, and skin complications related to the temperature management device. Results A total of 1850 patients were evaluated for the primary outcome. At 6 months, 465 of 925 patients (50%) in the hypothermia group had died, as compared with 446 of 925 (48%) in the normothermia group (relative risk with hypothermia, 1.04; 95% confidence interval [CI], 0.94 to 1.14; P=0.37). Of the 1747 patients in whom the functional outcome was assessed, 488 of 881 (55%) in the hypothermia group had moderately severe disability or worse (modified Rankin scale score >= 4), as compared with 479 of 866 (55%) in the normothermia group (relative risk with hypothermia, 1.00; 95% CI, 0.92 to 1.09). Outcomes were consistent in the prespecified subgroups. Arrhythmia resulting in hemodynamic compromise was more common in the hypothermia group than in the normothermia group (24% vs. 17%, P<0.001). The incidence of other adverse events did not differ significantly between the two groups. Conclusions In patients with coma after out-of-hospital cardiac arrest, targeted hypothermia did not lead to a lower incidence of death by 6 months than targeted normothermia. (Funded by the Swedish Research Council and others; TTM2 ClinicalTrials.gov number, .)
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| 23. |
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| 24. |
- Hilton, Matt, et al.
(författare)
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The XMM Cluster Survey : evidence for energy injection at high redshift from evolution of the X-ray luminosity-temperature relation
- 2012
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 424:3, s. 2086-2096
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Tidskriftsartikel (refereegranskat)abstract
- We measure the evolution of the X-ray luminositytemperature (LX - T) relation since z similar to 1.5 using a sample of 211 serendipitously detected galaxy clusters with spectroscopic redshifts drawn from the XMM Cluster Survey first data release (XCS-DR1). This is the first study spanning this redshift range using a single, large, homogeneous cluster sample. Using an orthogonal regression technique, we find no evidence for evolution in the slope or intrinsic scatter of the relation since z similar to 1.5, finding both to be consistent with previous measurements at z similar to 0.1. However, the normalization is seen to evolve negatively with respect to the self-similar expectation: we find E-1(z)?LX = 1044.67 +/- 0.09(T/5)3.04 +/- 0.16(1 + z)-1.5 +/- 0.5, which is within 2 sigma of the zero evolution case. We see milder, but still negative, evolution with respect to self-similar when using a bisector regression technique. We compare our results to numerical simulations, where we fit simulated cluster samples using the same methods used on the XCS data. Our data favour models in which the majority of the excess entropy required to explain the slope of the LX - T relation is injected at high redshift. Simulations in which active galactic nucleus feedback is implemented using prescriptions from current semi-analytic galaxy formation models predict the positive evolution of the normalization, and differ from our data at more than 5 sigma. This suggests that more efficient feedback at high redshift may be needed in these models.
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| 25. |
- Lampeitl, H., et al.
(författare)
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First-year Sloan Digital Sky Survey-II supernova results : consistency and constraints with other intermediate-redshift data sets
- 2010
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 401:4, s. 2331-2342
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Tidskriftsartikel (refereegranskat)abstract
- We present an analysis of the luminosity distances of Type Ia Supernovae (SNe) from the Sloan Digital Sky Survey-II (SDSS-II) SN Survey in conjunction with other intermediate-redshift (z < 0.4) cosmological measurements including redshift-space distortions from the Two-Degree Field Galaxy Redshift Survey (2dFGRS), the integrated Sachs–Wolfe (ISW) effect seen by the SDSS and the latest baryon acoustic oscillation (BAO) distance scale from both the SDSS and 2dFGRS. We have analysed the SDSS-II SN data alone using a variety of ‘model-independent’ methods and find evidence for an accelerating Universe at a >97 per cent level from this single data set. We find good agreement between the SN and BAO distance measurements, both consistent with a Λ-dominated cold dark matter cosmology, as demonstrated through an analysis of the distance duality relationship between the luminosity (dL) and angular diameter (dA) distance measures. We then use these data to estimate w within this restricted redshift range (z < 0.4). Our most stringent result comes from the combination of all our intermediate-redshift data (SDSS-II SNe, BAO, ISW and redshift-space distortions), giving w=−0.81+0.16−0.18 (stat) ± 0.15 (sys) and ΩM= 0.22+0.09−0.08 assuming a flat universe. This value of w and associated errors only change slightly if curvature is allowed to vary, consistent with constraints from the cosmic microwave background. We also consider more limited combinations of the geometrical (SN, BAO) and dynamical (ISW, redshift-space distortions) probes.
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| 26. |
- Leloudas, G., et al.
(författare)
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SN 2006oz : rise of a super-luminous supernova observed by the SDSS-II SN Survey
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 541, s. A129-
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Tidskriftsartikel (refereegranskat)abstract
- Context. A new class of super-luminous transients has recently been identified. These objects reach absolute luminosities of M-u < -21, lack hydrogen in their spectra, and are exclusively discovered by non-targeted surveys because they are associated with very faint galaxies. Aims. We aim to contribute to a better understanding of these objects by studying SN 2006oz, a newly-recognized member of this class. Methods. We present multi-color light curves of SN 2006oz from the SDSS-II SN Survey that cover its rise time, as well as an optical spectrum that shows that the explosion occurred at z similar to 0.376. We fitted black-body functions to estimate the temperature and radius evolution of the photosphere and used the parametrized code SYNOW to model the spectrum. We constructed a bolometric light curve and compared it with explosion models. In addition, we conducted a deep search for the host galaxy with the 10 m GTC telescope. Results. The very early light curves show a dip in the g-and r-bands and a possible initial cooling phase in the u-band before rising to maximum light. The bolometric light curve shows a precursor plateau with a duration of 6-10 days in the rest-frame. A lower limit of M-u < -21.5 can be placed on the absolute peak luminosity of the SN, while the rise time is constrained to be at least 29 days. During our observations, the emitting sphere doubled its radius to similar to 2 x 10(15) cm, while the temperature remained hot at similar to 15 000 K. As for other similar SNe, the spectrum is best modeled with elements including O II and Mg II, while we tentatively suggest that Fe III might be present. The host galaxy is detected in gri with 25.74 +/- 0.19, 24.43 +/- 0.06, and 24.14 +/- 0.12, respectively. It is a faint dwarf galaxy with M-g = -16.9. Conclusions. We suggest that the precursor plateau might be related to a recombination wave in a circumstellar medium (CSM) and discuss whether this is a common property of all similar explosions. The subsequent rise can be equally well described by input from a magnetar or by ejecta-CSM interaction, but the models are not well constrained owing to the lack of post-maximum observations, and CSM interaction has difficulties accounting for the precursor plateau self-consistently. Radioactive decay is less likely to be the mechanism that powers the luminosity. The host is a moderately young and star-forming, but not a starburst, galaxy.
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| 27. |
- Stott, J. P., et al.
(författare)
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THE XMM CLUSTER SURVEY : THE BUILD-UP OF STELLAR MASS IN BRIGHTEST CLUSTER GALAXIES AT HIGH REDSHIFT
- 2010
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 718:1, s. 23-30
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Tidskriftsartikel (refereegranskat)abstract
- We present deep J-and K-s-band photometry of 20 high redshift galaxy clusters between z = 0.8 and 1.5, 19 of which are observed with the MOIRCS instrument on the Subaru telescope. By using near-infrared light as a proxy for stellar mass we find the surprising result that the average stellar mass of Brightest Cluster Galaxies (BCGs) has remained constant at similar to 9 x 10(11) M-circle dot since z similar to 1.5. We investigate the effect on this result of differing star formation histories generated by three well-known and independent stellar population codes and find it to be robust for reasonable, physically motivated choices of age and metallicity. By performing Monte Carlo simulations we find that the result is unaffected by any correlation between BCG mass and cluster mass in either the observed or model clusters. The large stellar masses imply that the assemblage of these galaxies took place at the same time as the initial burst of star formation. This result leads us to conclude that dry merging has had little effect on the average stellar mass of BCGs over the last 9-10 Gyr in stark contrast to the predictions of semi-analytic models, based on the hierarchical merging of dark matter halos, which predict a more protracted mass build-up over a Hubble time. However, we discuss that there is potential for reconciliation between observation and theory if there is a significant growth of material in the intracluster light over the same period.
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| 28. |
- Jacobs, I, et al.
(författare)
-
Cardiac Arrest and Cardiopulmonary Resuscitation Outcome Reports : update and simplification of the Utstein templates for resuscitation registries. A statement for healthcare professionals from a task force of the international liaison committee on resuscitation (American Heart Association, European Resuscitation Council, Australian Resuscitation Council, New Zealand Resuscitation Council, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Council of Southern Africa).
- 2004
-
Ingår i: Circulation. - : Lippincott Williams & Wilkins. - 0009-7322 .- 1524-4539. ; 110:21, s. 3385-3397
-
Tidskriftsartikel (refereegranskat)abstract
- Outcome after cardiac arrest and cardiopulmonary resuscitation is dependent on critical interventions, particularly early defibrillation, effective chest compressions, and advanced life support. Utstein-style definitions and reporting templates have been used extensively in published studies of cardiac arrest, which has led to greater understanding of the elements of resuscitation practice and progress toward international consensus on science and resuscitation guidelines. Despite the development of Utstein templates to standardize research reports of cardiac arrest, international registries have yet to be developed. In April 2002, a task force of the International Liaison Committee on Resuscitation (ILCOR) met in Melbourne, Australia, to review worldwide experience with the Utstein definitions and reporting templates. The task force revised the core reporting template and definitions by consensus. Care was taken to build on previous definitions, changing data elements and operational definitions only on the basis of published data and experience derived from those registries that have used Utstein-style reporting. Attention was focused on decreasing the complexity of the existing templates and addressing logistical difficulties in collecting specific core and supplementary (ie, essential and desirable) data elements recommended by previous Utstein consensus conferences. Inconsistencies in terminology between in-hospital and out-of-hospital Utstein templates were also addressed. The task force produced a reporting tool for essential data that can be used for both quality improvement (registries) and research reports and that should be applicable to both adults and children. The revised and simplified template includes practical and succinct operational definitions. It is anticipated that the revised template will enable better and more accurate completion of all reports of cardiac arrest and resuscitation attempts. Problems with data definition, collection, linkage, confidentiality, management, and registry implementation are acknowledged and potential solutions offered. Uniform collection and tracking of registry data should enable better continuous quality improvement within every hospital, emergency medical services system, and community.
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| 29. |
- Jacobs, I, et al.
(författare)
-
Update and Simplification of the Utstein Templates for Resuscitation Registries : A Statement for Healthcare Professionals From a Task Force of the International Liaison Committee on Resuscitation
- 2004
-
Ingår i: Resuscitation. - : Elsevier Ireland Ltd. - 0300-9572 .- 1873-1570. ; 63:3, s. 233-249
-
Tidskriftsartikel (refereegranskat)abstract
- Outcome following cardiac arrest and cardiopulmonary resuscitation is dependent on critical interventions, particularly early defibrillation, effective chest compressions, and advanced life support. Utstein-style definitions and reporting templates have been used extensively in published studies of cardiac arrest, which has led to greater understanding of the elements of resuscitation practice and progress toward international consensus on science and resuscitation guidelines. Despite the development of Utstein templates to standardize research reports of cardiac arrest, international registries have yet to be developed. In April 2002 a task force of ILCOR met in Melbourne, Australia, to review worldwide experience with the Utstein definitions and reporting templates. The task force revised the core reporting template and definitions by consensus. Care was taken to build on previous definitions, changing data elements and operational definitions only on the basis of published data and experience derived from those registries that have used Utstein-style reporting. Attention was focused on decreasing the complexity of the existing templates and addressing logistical difficulties in collecting specific core and supplementary (i.e., essential and desirable) data elements recommended by previous Utstein consensus conference. Inconsistencies in terminology between in-hospital and out-of-hospital Utstein templates were also addressed. The task force produced a reporting tool for essential data that can be used for both quality improvement (registries) and research reports and that should be applicable to both adults and children. The revised and simplified template includes practical and succinct operational definitions. It is anticipated that the revised template will enable better and more accurate completion of all reports of cardiac arrest and resuscitation attempts. Problems with data definition, collection, linkage, confidentiality, management, and registry implementation are acknowledged and potential solutions offered. Uniform collection and tracking of registry data should enable better continuous quality improvement within every hospital, EMS system, and community.
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| 30. |
- Lloyd-Davies, E. J., et al.
(författare)
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The XMM Cluster Survey : X-ray analysis methodology
- 2011
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 418:1, s. 14-53
-
Tidskriftsartikel (refereegranskat)abstract
- The XMM Cluster Survey (XCS) is a serendipitous search for galaxy clusters using all publicly available data in the XMMNewton Science Archive. Its main aims are to measure cosmological parameters and trace the evolution of X-ray scaling relations. In this paper we describe the data processing methodology applied to the 5776 XMM observations used to construct the current XCS source catalogue. A total of 3675 > 4s cluster candidates with > 50 background-subtracted X-ray counts are extracted from a total non-overlapping area suitable for cluster searching of 410 deg2. Of these, 993 candidates are detected with > 300 background-subtracted X-ray photon counts, and we demonstrate that robust temperature measurements can be obtained down to this count limit. We describe in detail the automated pipelines used to perform the spectral and surface brightness fitting for these candidates, as well as to estimate redshifts from the X-ray data alone. A total of 587 (122) X-ray temperatures to a typical accuracy of < 40 (< 10) per cent have been measured to date. We also present the methodology adopted for determining the selection function of the survey, and show that the extended source detection algorithm is robust to a range of cluster morphologies by inserting mock clusters derived from hydrodynamical simulations into real XMMimages. These tests show that the simple isothermal beta-profiles is sufficient to capture the essential details of the cluster population detected in the archival XMM observations. The redshift follow-up of the XCS cluster sample is presented in a companion paper, together with a first data release of 503 optically confirmed clusters.
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| 31. |
- Robba, C., et al.
(författare)
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Ventilation management and outcomes in out-of-hospital cardiac arrest: a protocol for a preplanned secondary analysis of the TTM2 trial
- 2022
-
Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 12:3
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction Mechanical ventilation is a fundamental component in the management of patients post cardiac arrest. However, the ventilator settings and the gas-exchange targets used after cardiac arrest may not be optimal to minimise post-anoxic secondary brain injury. Therefore, questions remain regarding the best ventilator management in such patients. Methods and analysis This is a preplanned analysis of the international randomised controlled trial, targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest (OHCA)-target temperature management 2 (TTM2). The primary objective is to describe ventilatory settings and gas exchange in patients who required invasive mechanical ventilation and included in the TTM2 trial. Secondary objectives include evaluating the association of ventilator settings and gas-exchange values with 6 months mortality and neurological outcome. Adult patients after an OHCA who were included in the TTM2 trial and who received invasive mechanical ventilation will be eligible for this analysis. Data collected in the TTM2 trial that will be analysed include patients' prehospital characteristics, clinical examination, ventilator settings and arterial blood gases recorded at hospital and intensive care unit (ICU) admission and daily during ICU stay. Ethics and dissemination The TTM2 study has been approved by the regional ethics committee at Lund University and by all relevant ethics boards in participating countries. No further ethical committee approval is required for this secondary analysis. Data will be disseminated to the scientific community by abstracts and by original articles submitted to peer-reviewed journals.
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| 32. |
- Sako, Masao, et al.
(författare)
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The Data Release of the Sloan Digital Sky Survey-II Supernova Survey
- 2018
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 130:988
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes the data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, and ancillary data are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg(2) area along the celestial equator. This data release is comprised of all transient sources brighter than r similar or equal to 22.5 mag with no history of variability prior to 2004. Dedicated spectroscopic observations were performed on a subset of 889 transients, as well as spectra for thousands of transient host galaxies using the SDSS-III BOSS spectrographs. Photometric classifications are provided for the candidates with good multi-color light curves that were not observed spectroscopically, using host galaxy redshift information when available. From these observations, 4607 transients are either spectroscopically confirmed, or likely to be, supernovae, making this the largest sample of supernova candidates ever compiled. We present a new method for SN host-galaxy identification and derive host-galaxy properties including stellar masses, star formation rates, and the average stellar population ages from our SDSS multi-band photometry. We derive SALT2 distance moduli for a total of 1364 SN. Ia with spectroscopic redshifts as well as photometric redshifts for a further 624 purely photometric SN. Ia candidates. Using the spectroscopically confirmed subset of the three-year SDSS-II SN. Ia sample and assuming a flat.CDM cosmology, we determine Omega(M) = 0.315 +/- 0.093 (statistical error only) and detect a non-zero cosmological constant at 5.7 sigma.
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| 33. |
- Smith, Mathew, et al.
(författare)
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THE EFFECT OF WEAK LENSING ON DISTANCE ESTIMATES FROM SUPERNOVAE
- 2014
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 780:1, s. Art.nr.-UNSP 24
-
Tidskriftsartikel (refereegranskat)abstract
- Using a sample of 608 Type Ia supernovae from the SDSS-II and BOSS surveys, combined with a sample of foreground galaxies from SDSS-II, we estimate the weak lensing convergence for each supernova line of sight. We find that the correlation between this measurement and the Hubble residuals is consistent with the prediction from lensing (at a significance of 1.7 sigma). Strong correlations are also found between the residuals and supernova nuisance parameters after a linear correction is applied. When these other correlations are taken into account, the lensing signal is detected at 1.4 sigma. We show, for the first time, that distance estimates from supernovae can be improved when lensing is incorporated, by including a new parameter in the SALT2 methodology for determining distance moduli. The recovered value of the new parameter is consistent with the lensing prediction. Using cosmic microwave background data from WMAP7, H-0 data from Hubble Space Telescope and Sloan Digital Sky Survey (SDSS) Baryon acoustic oscillations measurements, we find the best-fit value of the new lensing parameter and show that the central values and uncertainties on Omega m and w are unaffected. The lensing of supernovae, while only seen at marginal significance in this low-redshift sample, will be of vital importance for the next generation of surveys, such as DES and LSST, which will be systematics-dominated.
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| 34. |
- Sollerman, J., et al.
(författare)
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First-Year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results : Constraints on Nonstandard Cosmological Models
- 2009
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 703:2, s. 1374-1385
-
Tidskriftsartikel (refereegranskat)abstract
- We use the new Type Ia supernovae discovered by the Sloan Digital Sky Survey-II supernova survey, together with additional supernova data sets as well as observations of the cosmic microwave background and baryon acoustic oscillations to constrain cosmological models. This complements the standard cosmology analysis presented by Kessler et al. in that we discuss and rank a number of the most popular nonstandard cosmology scenarios. When this combined data set is analyzed using the MLCS2k2 light-curve fitter, we find that more exotic models for cosmic acceleration provide a better fit to the data than the ΛCDM model. For example, the flat Dvali-Gabadadze-Porrati model is ranked higher by our information-criteria (IC) tests than the standard model with a flat universe and a cosmological constant. When the supernova data set is instead analyzed using the SALT-II light-curve fitter, the standard cosmological-constant model fares best. This investigation of how sensitive cosmological model selection is to assumptions about, and within, the light-curve fitters thereby highlights the need for an improved understanding of these unresolved systematic effects. Our investigation also includes inhomogeneous Lemaître-Tolman-Bondi (LTB) models. While our LTB models can be made to fit the supernova data as well as any other model, the extra parameters they require are not supported by our IC analysis. Finally, we explore more model-independent ways to investigate the cosmic expansion based on this new data set.
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| 35. |
- Dankiewicz, Josef, et al.
(författare)
-
Targeted hypothermia versus targeted Normothermia after out-of-hospital cardiac arrest (TTM2): A randomized clinical trial - Rationale and design
- 2019
-
Ingår i: American Heart Journal. - : Elsevier BV. - 0002-8703 .- 1097-6744. ; 217, s. 23-31
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Less than 500 participants have been included in randomized trials comparing hypothermia with regular care for out-of-hospital cardiac arrest patients, and many of these trials were small and at a high risk of bias. Consequently, the accrued data on this potentially beneficial intervention resembles that of a drug following small phase II trials. A large confirmatory trial is therefore warranted. Methods: The TTM2-trial is an international, multicenter, parallel group, investigator-initiated, randomized, superiority trial in which a target temperature of 33°C after cardiac arrest will be compared with a strategy to maintain normothermia and early treatment of fever (≥37.8°C). Participants will be randomized within 3 hours of return of spontaneous circulation with the intervention period lasting 40 hours in both groups. Sedation will be mandatory for all patients throughout the intervention period. The clinical team involved with direct patient care will not be blinded to allocation group due to the inherent difficulty in blinding the intervention. Prognosticators, outcome-assessors, the steering group, the trial coordinating team, and trial statistician will be blinded. The primary outcome will be all-cause mortality at 180 days after randomization. We estimate a 55% mortality in the control group. To detect an absolute risk reduction of 7.5% with an alpha of 0.05 and 90% power, 1900 participants will be enrolled. The main secondary neurological outcome will be poor functional outcome (modified Rankin Scale 4–6) at 180 days after arrest. Discussion: The TTM2-trial will compare hypothermia to 33°C with normothermia and early treatment of fever (≥37.8°C) after out-of-hospital cardiac arrest. © 2019
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| 36. |
- Nishiyama, C, et al.
(författare)
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Apples to apples or apples to oranges? International variation in reporting of process and outcome of care for out-of-hospital cardiac arrest
- 2014
-
Ingår i: Resuscitation. - : Elsevier Ireland Ltd.. - 0300-9572 .- 1873-1570. ; 85:11, s. 1599-1609
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Survival after out-of-hospital cardiac arrest (OHCA) varies between communities, due in part to variation in the methods of measurement. The Utstein template was disseminated to standardize comparisons of risk factors, quality of care, and outcomes in patients with OHCA. We sought to assess whether OHCA registries are able to collate common data using the Utstein template. A subsequent study will assess whether the Utstein factors explain differences in survival between emergency medical services (EMS) systems. STUDY DESIGN: Retrospective study. SETTING: This retrospective analysis of prospective cohorts included adults treated for OHCA, regardless of the etiology of arrest. Data describing the baseline characteristics of patients, and the process and outcome of their care were grouped by EMS system, de-identified, and then collated. Included were core Utstein variables and timed event data from each participating registry. This study was classified as exempt from human subjects' research by a research ethics committee. MEASUREMENTS AND MAIN RESULTS: Thirteen registries with 265 first-responding EMS agencies in 13 countries contributed data describing 125,840 cases of OHCA. Variation in inclusion criteria, definition, coding, and process of care variables were observed. Contributing registries collected 61.9% of recommended core variables and 42.9% of timed event variables. Among core variables, the proportion of missingness was mean 1.9±2.2%. The proportion of unknown was mean 4.8±6.4%. Among time variables, missingness was mean 9.0±6.3%. CONCLUSIONS: International differences in measurement of care after OHCA persist. Greater consistency would facilitate improved resuscitation care and comparison within and between communities.
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| 37. |
- Nolan, Jerry P, et al.
(författare)
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Intensive care medicine research agenda on cardiac arrest
- 2017
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Ingår i: Intensive Care Medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 43:9, s. 1282-1293
-
Tidskriftsartikel (refereegranskat)abstract
- Over the last 15 years, treatment of comatose post-cardiac arrest patients has evolved to include therapeutic strategies such as urgent coronary angiography with percutaneous coronary intervention (PCI), targeted temperature management (TTM)—requiring mechanical ventilation and sedation—and more sophisticated and cautious prognostication. In 2015, collaboration between the European Resuscitation Council (ERC) and the European Society for Intensive Care Medicine (ESICM) resulted in the first European guidelines on post-resuscitation care. This review addresses the major recent advances in the treatment of cardiac arrest, recent trials that have challenged current practice and the remaining areas of uncertainty.
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| 38. |
- Nordin, Jakob, et al.
(författare)
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Spectral properties of Type Ia supernovae up to z~0.3
- 2011
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 526, s. A119-
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: Spectroscopic observations of type Ia supernovae obtained at the New Technology Telescope (NTT) and the Nordic Optical Telescope (NOT), in conjunction with the SDSS-II Supernova Survey, are analysed. We use spectral indicators measured up to a month after the lightcurve peak luminosity to characterise the supernova properties, and examine these for potential correlations with host galaxy type, lightcurve shape, colour excess, and redshift. Methods: Our analysis is based on 89 type Ia supernovae at a redshift interval z = 0.05-0.3, for which multiband SDSS photometry is available. A lower-z spectroscopy reference sample was used for comparisons over cosmic time. We present measurements of time series of pseudo equivalent widths and line velocities of the main spectral features in type Ia supernovae. Results: Supernovae with shallower features are found predominantly among the intrinsically brighter slow declining supernovae. We detect the strongest correlation between lightcurve stretch and the Si ii λ4000 absorption feature, which also correlates with the estimated mass and star formation rate of the host galaxy. We also report a tentative correlation between colour excess and spectral properties. If confirmed, this would suggest that moderate reddening of type Ia supernovae is dominated by effects in the explosion or its immediate environment, as opposed to extinction by interstellar dust.
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| 39. |
- Östman, Linda, et al.
(författare)
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NTT and NOT spectroscopy of SDSS-II supernovae
- 2011
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 526, s. A28-
-
Tidskriftsartikel (refereegranskat)abstract
- Context. The Sloan Digital Sky Survey II (SDSS-II) Supernova Survey, conducted between 2005 and 2007, was designed to detect a large number of type Ia supernovae around z ~ 0.2, the redshift "gap" between low-z and high-z supernova searches. The survey has provided multi-band (ugriz) photometric lightcurves for variable targets, and supernova candidates were scheduled for spectroscopic observations, primarily to provide supernova classification and accurate redshifts. We present supernova spectra obtained in 2006 and 2007 using the New Technology Telescope (NTT) and the Nordic Optical Telescope (NOT). Aims: We provide an atlas of supernova spectra in the range z = 0.03-0.32 that complements the well-sampled lightcurves from SDSS-II in the forthcoming three-year SDSS supernova cosmology analysis. The sample can, for example, be used for spectral studies of type Ia supernovae, which are critical for understanding potential systematic effects when supernovae are used to determine cosmological distances. Methods: The spectra were reduced in a uniform manner, and special care was taken in estimating the uncertainties for the different processing steps. Host-galaxy light was subtracted when possible and the supernova type fitted using the SuperNova IDentification code (SNID). We also present comparisons between spectral and photometric dating using SALT lightcurve fits to the photometry from SDSS-II, as well as the global distribution of our sample in terms of the lightcurve parameters: stretch and colour. Results: We report new spectroscopic data from 141 type Ia supernovae, mainly between -9 and +15 days from lightcurve maximum, including a few cases of multi-epoch observations. This homogeneous, host-galaxy subtracted, type Ia supernova spectroscopic sample is among the largest such data sets and unique in its redshift interval. The sample includes two potential SN 1991T-like supernovae (SN 2006on and SN 2007ni) and one potential SN 2002cx-like supernova (SN 2007ie). In addition, the new compilation includes spectra from 23 confirmed type II and 8 type Ib/c supernovae.
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| 40. |
- Astier, P., et al.
(författare)
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Extending the supernova Hubble diagram to z similar to 1.5 with the Euclid space mission
- 2014
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 572, s. A80-
-
Tidskriftsartikel (refereegranskat)abstract
- We forecast dark energy constraints that could be obtained from a new large sample of Type Ia supernovae where those at high redshift are acquired with the Euclid space mission. We simulate a three-prong SN survey: a z < 0.35 nearby sample (8000 SNe), a 0.2 < z < 0.95 intermediate sample (8800 SNe), and a 0.75 < z < 1.55 high-z sample (1700 SNe). The nearby and intermediate surveys are assumed to be conducted from the ground, while the high-z is a joint ground-and space-based survey. This latter survey, the Dark Energy Supernova Infra-Red Experiment (DESIRE), is designed to fit within 6 months of Euclid observing time, with a dedicated observing programme. We simulate the SN events as they would be observed in rolling-search mode by the various instruments, and derive the quality of expected cosmological constraints. We account for known systematic uncertainties, in particular calibration uncertainties including their contribution through the training of the supernova model used to fit the supernovae light curves. Using conservative assumptions and a 1D geometric Planck prior, we find that the ensemble of surveys would yield competitive constraints: a constant equation of state parameter can be constrained to sigma(omega) = 0.022, and a Dark Energy Task Force figure of merit of 203 is found for a two-parameter equation of state. Our simulations thus indicate that Euclid can bring a significant contribution to a purely geometrical cosmology constraint by extending a high-quality SN Ia Hubble diagram to z similar to 1.5. We also present other science topics enabled by the DESIRE Euclid observations.
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| 41. |
- Campbell, Heather, et al.
(författare)
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COSMOLOGY WITH PHOTOMETRICALLY CLASSIFIED TYPE Ia SUPERNOVAE FROM THE SDSS-II SUPERNOVA SURVEY
- 2013
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 763:2, s. 88-
-
Tidskriftsartikel (refereegranskat)abstract
- We present the cosmological analysis of 752 photometrically classified Type Ia Supernovae (SNe Ia) obtained from the full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented with host-galaxy spectroscopy from the SDSS-III Baryon Oscillation Spectroscopic Survey. Our photometric-classification method is based on the SN classification technique of Sako et al., aided by host-galaxy redshifts (0.05 < z < 0.55). SuperNova ANAlysis simulations of our methodology estimate that we have an SN Ia classification efficiency of 70.8%, with only 3.9% contamination from core-collapse (non-Ia) SNe. We demonstrate that this level of contamination has no effect on our cosmological constraints. We quantify and correct for our selection effects (e. g., Malmquist bias) using simulations. When fitting to a flat.CDM cosmological model, we find that our photometric sample alone gives Omega(m) = 0.24(-0.05)(+0.07) (statistical errors only). If we relax the constraint on flatness, then our sample provides competitive joint statistical constraints on Omega(m) and Omega(Lambda), comparable to those derived from the spectroscopically confirmed Three-year Supernova Legacy Survey (SNLS3). Using only our data, the statistics-only result favors an accelerating universe at 99.96% confidence. Assuming a constant wCDM cosmological model, and combining with H-0, cosmic microwave background, and luminous red galaxy data, we obtain w = -0.96(-0.10)(+0.10), Omega(m) = 0.29(-0.02)(+0.02), and Omega(k) = 0.00(-0.02)(+0.03)(statistical errors only), which is competitive with similar spectroscopically confirmed SNe Ia analyses. Overall this comparison is reassuring, considering the lower redshift leverage of the SDSS-II SN sample (z < 0.55) and the lack of spectroscopic confirmation used herein. These results demonstrate the potential of photometrically classified SN Ia samples in improving cosmological constraints.
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| 42. |
- D'Andrea, Chris B., et al.
(författare)
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Type II-P Supernovae from the SDSS-II Supernova Survey and the Standardized Candle Method
- 2010
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 708:1, s. 661-674
-
Tidskriftsartikel (refereegranskat)abstract
- We apply the Standardized Candle Method (SCM) for Type II Plateau supernovae (SNe II-P), which relates the velocity of the ejecta of a SN to its luminosity during the plateau, to 15 SNe II-P discovered over the three season run of the Sloan Digital Sky Survey-II Supernova Survey. The redshifts of these SNe—0.027 < z < 0.144—cover a range hitherto sparsely sampled in the literature; in particular, our SNe II-P sample contains nearly as many SNe in the Hubble flow (z > 0.01) as all of the current literature on the SCM combined. We find that the SDSS SNe have a very small intrinsic I-band dispersion (0.22 mag), which can be attributed to selection effects. When the SCM is applied to the combined SDSS-plus-literature set of SNe II-P, the dispersion increases to 0.29 mag, larger than the scatter for either set of SNe separately. We show that the standardization cannot be further improved by eliminating SNe with positive plateau decline rates, as proposed in Poznanski et al. We thoroughly examine all potential systematic effects and conclude that for the SCM to be useful for cosmology, the methods currently used to determine the Fe II velocity at day 50 must be improved, and spectral templates able to encompass the intrinsic variations of Type II-P SNe will be needed. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.
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| 43. |
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