A5058540314- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Cosmology and Gravitation Theories
- CCD and CMOS Imaging Sensors
- Geophysics and Gravity Measurements
- Hepatocellular Carcinoma Treatment and Prognosis
- Adaptive optics and wavefront sensing
- Cancer, Hypoxia, and Metabolism
- Dark Matter and Cosmic Phenomena
- Nuclear Physics and Applications
- Renal cell carcinoma treatment
- Radio Astronomy Observations and Technology
- Medical Imaging Techniques and Applications
- Calibration and Measurement Techniques
- MRI in cancer diagnosis
- Medical Imaging and Pathology Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Solar and Space Plasma Dynamics
University of Pennsylvania
2016-2025
Ludwig-Maximilians-Universität München
2024
Aix-Marseille Université
2024
Austin Peay State University
2024
University of Zurich
2024
American Public University System
2024
Stanford University
2005-2024
Oak Ridge National Laboratory
2024
Lancaster University
2024
Centre National de la Recherche Scientifique
2024
Aims. We present cosmological constraints from a joint analysis of type Ia 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 (0.05 <z< 0.4), years (0.2 1), it totals 740 spectroscopically confirmed supernovae with high-quality light curves.
The ESA X-ray Multi Mirror mission, XMM-Newton, carries two identical Reflection Grating Spectrometers (RGS) behind of its three nested sets Wolter I type mirrors. instrument allows high-resolution ( to 500) measurements in the soft range (6 38 Åor 2.1 0.3 keV) with a maximum effective area about 140 cm2 at 15 Å. Its design is optimized for detection K-shell transitions carbon, nitrogen, oxygen, neon, magnesium, and silicon, as well L shell iron. present paper gives full description RGS...
We present measurements of the Hubble diagram for 103 Type Ia supernovae (SNe) with redshifts 0.04 < z 0.42, discovered during first season (Fall 2005) Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data fill in redshift "desert" between low- and high-redshift SN surveys. combine SDSS-II new distance estimates published from ESSENCE survey, Legacy Survey, Space Telescope, a compilation nearby measurements. Combining Baryon Acoustic Oscillations SDSS Luminous Red Galaxy sample...
We present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift $z=0.001$ to 2.26. This work features an increased sample size, span, and improved treatment systematic uncertainties comparison original Pantheon results a factor two improvement constraining power. For Flat$\Lambda$CDM model, we find $\Omega_M=0.334\pm0.018$ SNe alone. Flat$w_0$CDM measure $w_0=-0.90\pm0.14$ alone, H$_0=73.5\pm1.1$...
Abstract We present the Dark Energy Camera (DECam) discovery of optical counterpart first binary neutron star merger detected through gravitational-wave emission, GW170817. Our observations commenced 10.5 hr post-merger, as soon localization region became accessible from Chile. imaged 70 deg 2 in i and z bands, covering 93% initial integrated probability, to a depth necessary identify likely counterparts (e.g., kilonova). At 11.4 post-merger we bright transient located nucleus NGC 4993 at...
We report the discovery of eight new ultra-faint dwarf galaxy candidates in second year optical imaging data from Dark Energy Survey (DES). Six these are detected at high confidence, while two lower-confidence identified regions non-uniform survey coverage. The stellar systems found by three independent automated search techniques and as overdensities stars, consistent with isochrone luminosity function an old metal-poor simple population. faint (Mv > -4.7 mag) span a range physical sizes...
The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z 0.35) Type Ia supernovae (SNe Ia) using repeated five-band (ugriz) imaging over an area of 300 sq. deg. survey region is stripe 2.5° wide centered the celestial equator in Southern Galactic Cap that been imaged numerous times earlier years, enabling construction deep reference image discovery new objects. Supernova observations are being...
We report the discovery of eight new Milky Way companions in optical imaging data collected during first year Dark Energy Survey (DES). Each system is identified as a statistically significant over-density individual stars consistent with expected isochrone and luminosity function an old metal-poor stellar population. The objects span wide range absolute magnitudes (MV from to ), physical sizes (), heliocentric distances (). Based on low surface brightnesses, large sizes, and/or...
We report the discovery of rising X-ray emission from binary neutron star (BNS) merger event GW170817. This is first detection a gravitational-wave source. Observations acquired with Chandra Observatory (CXO) at t~2.3 days post reveal no significant emission, L_x<=3.2x10^38 erg/s (isotropic-equivalent). Continued monitoring revealed presence an source that brightened time, reaching L_x\sim 9x10^39 ~15.1 merger. interpret these findings in context isotropic and collimated relativistic...
We present Very Large Array (VLA) and Atacama Millimeter/sub-millimeter ALMA radio observations of GW\,170817, the first Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo gravitational wave (GW) event from a binary neutron star merger GW with an electromagnetic (EM) counterpart. Our data include following discovery optical transient at both centimeter ($13.7$ hours post merger) millimeter ($2.41$ days bands. detect faint emission 6 GHz 19.47 39.23 after merger, but not in...
We present a near-infrared spectral sequence of the electromagnetic counterpart to binary neutron star merger GW170817 detected by Advanced LIGO/Virgo. Our dataset comprises seven epochs J+H spectra taken with FLAMINGOS-2 on Gemini-South between 1.5 and 10.5 days after merger. In initial epoch, spectrum is dominated smooth blue continuum due high-velocity, lanthanide-poor kilonova component. Starting following night, all subsequent instead show features that are similar those predicted in...
Abstract We present optical and ultraviolet spectra of the first electromagnetic counterpart to a gravitational-wave (GW) source, binary neutron star merger GW170817. Spectra were obtained nightly between 1.5 9.5 days post-merger, using Southern Astrophysical Research Magellan telescopes; UV spectrum was with Hubble Space Telescope at 5.5 days. Our data reveal rapidly fading blue component ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>T</mml:mi>...
We present an improved measurement of the Hubble constant (H_0) using 'inverse distance ladder' method, which adds information from 207 Type Ia supernovae (SNe Ia) Dark Energy Survey (DES) at redshift 0.018 < z 0.85 to existing measurements 122 low (z 0.07) SNe (Low-z) and Baryon Acoustic Oscillations (BAOs). Whereas traditional H_0 with use a ladder parallax Cepheid variable stars, inverse relies on absolute BAOs calibrate intrinsic magnitude Ia. find = 67.8 +/- 1.3 km s-1 Mpc-1...
ABSTRACT We present a blind time-delay cosmographic analysis for the lens system DES J0408−5354. This is extraordinary presence of two sets multiple images at different redshifts, which provide opportunity to obtain more information cost increased modelling complexity with respect previously analysed systems. perform detailed mass distribution this using three band Hubble Space Telescope imaging. combine measured time delays, line-of-sight central velocity dispersion deflector, and...
We introduce redMaGiC, an automated algorithm for selecting Luminous Red Galaxies (LRGs). The was specifically developed to minimize photometric redshift uncertainties in large-scale structure studies. redMaGiC achieves this by self-training the color-cuts necessary produce a luminosity-thresholded LRG sample of constant comoving density. demonstrate that photozs are very nearly as accurate best machine-learning based methods, yet they require minimal spectroscopic training, do not suffer...
We present weak lensing shear catalogues for 139 square degrees of data taken during the Science Verification (SV) time new Dark Energy Camera (DECam) being used Survey (DES). describe our object selection, point spread function estimation and measurement procedures using two independent pipelines, im3shape ngmix, which produce 2.12 million 3.44 galaxies, respectively. detail a set null tests measurements find that they pass requirements systematic errors at level necessary science...
ABSTRACT We present angular diameter distance measurements obtained by locating the baryon acoustic oscillations (BAO) scale in distribution of galaxies selected from first year Dark Energy Survey data. consider a sample over 1.3 million distributed footprint 1336 deg2 with 0.6 < $z$photo 1 and typical redshift uncertainty 0.03(1 + $z$). This was selected, as fully described companion paper, using colour/magnitude selection that optimizes trade-offs between number density uncertainty....
ABSTRACT We measure the current expansion rate of Universe, Hubble’s constant $H_0$, by calibrating absolute magnitudes supernovae to distances measured baryon acoustic oscillations (BAO). This ‘inverse distance ladder’ technique provides an alternative using nearby measurements, replacing calibration with a high-redshift anchor. use recent release 1829 from Dark Energy Survey spanning $0.01\lt z\lt 1.13$ anchored oscillation measurements Spectroscopic Instrument (DESI) $0.30 \lt...
The Sloan Digital Sky Survey-II Supernova Survey has identified a large number of new transient sources in 300 deg2 region along the celestial equator during its first two seasons three-season campaign. Multi-band (ugriz) light curves were measured for most sources, which include solar system objects, galactic variable stars, active nuclei, supernovae (SNe), and other astronomical transients. imaging survey is augmented by an extensive spectroscopic follow-up program to identify SNe, measure...
We present extensive u'g'r'i'BVRIYJHKs photometry and optical spectroscopy of the Type Ia supernova (SN) 2005hk. These data reveal that SN 2005hk was nearly identical in its observed properties to 2002cx, which has been called "the most peculiar known supernova." Both supernovae exhibited high‐ionization 1991T–like premaximum spectra, yet low peak luminosities like 1991bg. The spectra 2005hk, expansion velocities were roughly half those typical supernovae. R I light curves both also not...
We present an analysis of the host galaxy dependences Type Ia Supernovae (SNe Ia) from full three year sample SDSS-II Supernova Survey. re-discover, to high significance, strong correlation between type and width observed SN light curve, i.e., fainter, quickly declining SNe favor passive galaxies, while brighter, slowly Ia's star-forming galaxies. also find evidence (at 2σ 3σ) that are ≃0.1 ± 0.04 mag brighter in galaxies than hosts, after curves have been standardized using light-curve...
We present ugriz light curves for 146 spectroscopically-confirmed or spectroscopically-probable Type Ia supernovae (SNe) from the 2005 season of Sloan Digital Sky Survey-II Supernova (SN) survey. The have been constructed using a photometric technique that we call scene modeling, which is described in detail here; major feature SN brightnesses are extracted stack images without spatial resampling convolution image data. This procedure produces accurate photometry along with estimates...
We use the new Type Ia supernovae discovered by Sloan Digital Sky Survey-II supernova survey, together with additional data sets as well observations of cosmic microwave background and baryon acoustic oscillations to constrain cosmological models. This complements standard cosmology analysis presented Kessler et al. in that we discuss rank a number most popular nonstandard scenarios. When this combined set is analyzed using MLCS2k2 light-curve fitter, find more exotic models for acceleration...
We present results from a study of the photometric redshift performance Dark Energy Survey (DES), using early data Science Verification period observations in late 2012 and 2013 that provided science-quality images for almost 200 sq. deg. at nominal depth survey. assess (photo-z) about 15 000 galaxies with spectroscopic redshifts available other surveys. These are used, different configurations, as calibration sample, photo-z's obtained studied most existing photo-z codes. A weighting method...
We describe a general analysis package for supernova (SN) light curves, called SNANA, that contains simulation, curve fitter, and cosmology fitter. The software is designed with the primary goal of using SNe Ia as distance indicators determination cosmological parameters, but it can also be used to study efficiencies analyses SN rates, estimate contamination from non-Ia SNe, optimize future surveys. Several models are available within same architecture, allowing technical features such...