J. L. Marshall
A5013213350- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Cosmology and Gravitation Theories
- Adaptive optics and wavefront sensing
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- CCD and CMOS Imaging Sensors
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Gaussian Processes and Bayesian Inference
- Counseling Practices and Supervision
- Scientific Research and Discoveries
- Impact of Light on Environment and Health
- Remote Sensing in Agriculture
- Aerodynamics and Fluid Dynamics Research
- Advanced Image Processing Techniques
- Neutrino Physics Research
Mitchell Institute
2016-2025
Texas A&M University
2016-2025
Institució Catalana de Recerca i Estudis Avançats
2023-2024
Kavli Institute for Particle Astrophysics and Cosmology
2023-2024
SLAC National Accelerator Laboratory
2023-2024
Laboratório Interinstitucional de e-Astronomia
2018-2024
Lawrence Berkeley National Laboratory
2023-2024
University Hospital Southampton NHS Foundation Trust
2022-2023
University of South Florida
2021-2023
Creative Commons
2023
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.
We present UV, optical, and NIR photometry of the first electromagnetic counterpart to a gravitational wave source from Advanced LIGO/Virgo, binary neutron star merger GW170817. Our data set extends discovery optical at $0.47$ days $18.5$ post-merger, includes observations with Dark Energy Camera (DECam), Gemini-South/FLAMINGOS-2 (GS/F2), {\it Hubble Space Telescope} ({\it HST}). The spectral energy distribution (SED) inferred this $0.6$ is well described by blackbody model $T\approx 8300$...
On 2017 August 17, gravitational waves were detected from a binary neutron star merger, GW170817, along with coincident short gamma-ray burst, GRB170817A. An optical transient source, Swope Supernova Survey 17a (SSS17a), was subsequently identified as the counterpart of this event. We present ultraviolet, and infrared light curves SSS17a extending 10.9 hours to 18 days post-merger. constrain radioactively-powered resulting ejection neutron-rich material. The fast rise curves, subsequent...
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...
The Dark Energy Camera is a new imager with 22 diameter field of view mounted at the prime focus Victor M. Blanco 4 m telescope on Cerro Tololo near La Serena, Chile. camera was designed and constructed by Survey Collaboration meets or exceeds stringent requirements for wide-field supernova surveys which collaboration uses it. consists five-element optical corrector, seven filters, shutter 60 cm aperture, charge-coupled device (CCD) focal plane 250 μm thick fully depleted CCDs cooled inside...
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...
ABSTRACT We search for excess γ -ray emission coincident with the positions of confirmed and candidate Milky Way satellite galaxies using six years data from Fermi Large Area Telescope (LAT). Our sample 45 stellar systems includes 28 kinematically dark-matter-dominated dwarf spheroidal (dSphs) 17 recently discovered that have photometric characteristics consistent population known dSphs. For each these targets, relative predicted flux due to dark matter annihilation is taken kinematic...
ABSTRACT We describe updates to the redMaPPer algorithm, a photometric red-sequence cluster finder specifically designed for large surveys. The updated algorithm is applied of Science Verification (SV) data from Dark Energy Survey (DES), and Sloan Digital Sky (SDSS) DR8 set. DES SV catalog locally volume limited contains 786 clusters with richness (roughly equivalent ) . consists 26,311 , sharply increasing threshold as function redshift performance both catalogs shown be excellent,...
On 2017 August 17, Swope Supernova Survey 2017a (SSS17a) was discovered as the optical counterpart of binary neutron star gravitational wave event GW170817. We report time-series spectroscopy SSS17a from 11.75 hours until 8.5 days after merger. Over first hour observations ejecta rapidly expanded and cooled. Applying blackbody fits to spectra, we measure photosphere cooling $11,000^{+3400}_{-900}$ K $9300^{+300}_{-300}$ K, determine a photospheric velocity roughly 30% speed light. The...
We present the discovery of KELT-1b, first transiting low-mass companion from wide-field Kilodegree Extremely Little Telescope-North (KELT-North) survey. The V=10.7 primary is a mildly evolved, solar-metallicity, mid-F star. brown dwarf or super-massive planet with mass 27.23+/-0.50 MJ and radius 1.110+0.037-0.024 RJ, on very short period (P=1.21750007) circular orbit. KELT-1b receives large amount stellar insolation, an equilibrium temperature assuming zero albedo perfect redistribution...
The Carnegie Supernova Project (CSP) was a five-year observational survey conducted at Las Campanas Observatory that obtained, among other things, high-quality light curves of ~100 low-redshift Type Ia supernovae (SNe Ia). Presented here is the second data release nearby SN photometry consisting 50 objects, with subset 45 having near-infrared follow-up observations. Thirty-three objects have optical pre-maximum coverage 15 beginning least 5 days before maximum light. In near-infrared, 27...
We combine Dark Energy Survey Year 1 clustering and weak lensing data with Baryon Acoustic Oscillations (BAO) Big Bang Nucleosynthesis (BBN) experiments to constrain the Hubble constant. Assuming a flat $\Lambda$CDM model minimal neutrino mass ($\sum m_\nu = 0.06$ eV) we find $H_0=67.2^{+1.2}_{-1.0}$ km/s/Mpc (68% CL). This result is completely independent of constant measurements based on distance ladder, Cosmic Microwave Background (CMB) anisotropies (both temperature polarization), strong...
We describe the creation, content, and validation of Dark Energy Survey (DES) internal year-one cosmology data set, Y1A1 GOLD, in support upcoming cosmological analyses. The GOLD set is assembled from multiple epochs DES imaging consists calibrated photometric zeropoints, object catalogs, ancillary products - e.g., maps survey depth observing conditions, star-galaxy classification, redshift estimates that are necessary for accurate wide-area catalog ~137 million objects detected coadded...
We perform a comprehensive study of Milky Way (MW) satellite galaxies to constrain the fundamental properties dark matter (DM). This analysis fully incorporates inhomogeneities in spatial distribution and detectability MW satellites marginalizes over uncertainties mapping between DM halos, system, disruption subhalos by disk. Our results are consistent with cold, collisionless paradigm yield strongest cosmological constraints date on particle models warm, interacting, fuzzy matter. At 95%...
We constrain the mass–richness scaling relation of redMaPPer galaxy clusters identified in Dark Energy Survey Year 1 data using weak gravitational lensing. split into 4 × 3 bins richness λ and redshift |$z$| for ≥ 20 0.2 ≤ 0.65 measure mean masses these their stacked lensing signal. By modelling as 〈M200m|λ, |$z$|〉 = M0(λ/40)F((1 + |$z$|)/1.35)G, we normalization at 5.0 per cent level, finding M0 [3.081 ± 0.075(stat) 0.133(sys)] · 1014 M⊙ 40 0.35. The recovered index is F 1.356 0.051 (stat)...
Due to their proximity, high dark-matter content, and apparent absence of non-thermal processes, Milky Way dwarf spheroidal satellite galaxies (dSphs) are excellent targets for the indirect detection dark matter. Recently, eight new dSph candidates were discovered using first year data from Dark Energy Survey (DES). We searched gamma-ray emission coincident with positions these objects in six years Fermi Large Area Telescope data. found no significant excesses emission. Under assumption that...
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 present final natural system optical (ugriBV) and near-infrared (YJH) photometry of 134 supernovae (SNe) with probable white dwarf progenitors that were observed in 2004-2009 as part the first stage Carnegie Supernova Project (CSP-I). The sample consists 123 Type Ia SNe, 5 Iax 2 super-Chandrasekhar SN candidates, SNe interacting circumstellar matter, 2006bt-like events. redshifts objects range from z = 0.0037 to 0.0835; median redshift is 0.0241. For 120 (90%) these was obtained. Average...
We describe the Dark Energy Survey (DES) photometric data set assembled from first three years of science operations to support DES Year 3 cosmology analyses, and provide usage notes aimed at broad astrophysics community. Y3 Gold improves on previous releases DES, Y1 Data Release 1 (DES DR1), presenting an expanded curated that incorporates algorithmic developments in image detrending processing, calibration, object classification. comprises nearly 5000 square degrees grizY imaging south...
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....