M. S. S. Gill
A5079210719- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- CCD and CMOS Imaging Sensors
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Advanced Scientific and Engineering Studies
- Nasal Surgery and Airway Studies
- Calibration and Measurement Techniques
- Natural Language Processing Techniques
- Solar and Space Plasma Dynamics
- Scientific Research and Discoveries
- Microbial Metabolic Engineering and Bioproduction
- Reservoir Engineering and Simulation Methods
- Health and Well-being Studies
- Advanced Image Processing Techniques
- Cardiovascular and Diving-Related Complications
SLAC National Accelerator Laboratory
2014-2024
Punjab Agricultural University
2024
Stanford University
2014-2022
Kavli Institute for Particle Astrophysics and Cosmology
2012-2022
National Center for Supercomputing Applications
2018
Baba Farid University of Health Sciences
2018
Institute of Engineering
2018
Large Synoptic Survey Telescope Corporation
2018
McMaster University
2012-2015
Touro University Nevada
2014
We present cosmological results from a combined analysis of galaxy clustering and weak gravitational lensing, using 1321 deg$^2$ $griz$ imaging data the first year Dark Energy Survey (DES Y1). combine three two-point functions: (i) cosmic shear correlation function 26 million source galaxies in four redshift bins, (ii) angular autocorrelation 650,000 luminous red five (iii) galaxy-shear cross-correlation positions shears. To demonstrate robustness these results, we use independent pairs...
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 $T\approx 8300$...
Abstract We describe the first public data release of Dark Energy Survey, DES DR1, consisting reduced single-epoch images, co-added source catalogs, and associated products services assembled over 3 yr science operations. DR1 is based on optical/near-infrared imaging from 345 distinct nights (2013 August to 2016 February) by Camera mounted 4 m Blanco telescope at Cerro Tololo Inter-American Observatory in Chile. wide-area survey covering ∼5000 deg 2 southern Galactic cap five broad...
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 present first results from the third GRavitational lEnsing Accuracy Testing (GREAT3) challenge, in a sequence of challenges for testing methods inferring weak gravitational lensing shear distortions simulated galaxy images. GREAT3 was divided into experiments to test three specific questions, and included space- ground-based data with constant or cosmologically varying fields. The simplest (control) experiment parametric galaxies realistic distribution signal-to-noise, size, ellipticity,...
In this paper, we present results from the weak-lensing shape measurement GRavitational lEnsing Accuracy Testing 2010 (GREAT10) Galaxy Challenge. This marks an order of magnitude step change in level scrutiny employed analysis. We provide descriptions each method tested and include 10 evaluation metrics over 24 simulation branches.
The GRavitational lEnsing Accuracy Testing 3 (GREAT3) challenge is the third in a series of image analysis challenges, with goal testing and facilitating development methods for analyzing astronomical images that will be used to measure weak gravitational lensing. This measurement requires extremely precise estimation very small galaxy shape distortions, presence far larger intrinsic shapes distortions due blurring kernel caused by atmosphere, telescope optics, instrumental effects. GREAT3...
We present a measurement of the Hubble constant $H_0$ using gravitational wave (GW) event GW190814, which resulted from coalescence 23 $M_\odot$ black hole with 2.6 compact object, as standard siren. No compelling electromagnetic counterpart has been identified for this event, thus our analysis accounts thousands potential host galaxies within statistical framework. The redshift information is obtained photometric (photo-$z$) catalog Dark Energy Survey. luminosity distance provided by...
Abstract We report the results of searches for strong gravitational lens systems in Dark Energy Survey (DES) Science Verification and Year 1 observations. The data span approximately 250 sq. deg. with a median i -band limiting magnitude extended objects (10 σ ) 23.0. 2000 have an 22.9. As these sets are both wide deep, they particularly useful identifying candidates. Potential candidate were initially identified based on color selection DES object catalogs or because system is at location...
We address the problem of optimally identifying all kilonovae detected via gravitational wave emission in upcoming LIGO/Virgo/KAGRA Collaboration observing run, O4, which is expected to be sensitive a factor $\sim 7$ more Binary Neutron Stars alerts than previously. Electromagnetic follow-up but brightest these new events will require $>1$ meter telescopes, for limited time available. present an optimized strategy Dark Energy Camera during O4. base our study on simulations O4 and wide-prior...
The weak gravitational lensing magnification of Type Ia supernovae (SNe Ia) is sensitive to the matter power spectrum on scales $k>1 h$ Mpc$^{-1}$, making it unwise interpret SNe in terms linear scales. We compute probability density function as a standard cosmological parameters, plus an empirical parameter $A_{\rm mod}$ which describes suppression or enhancement non-linear compared cold dark only model. While baryons are expected enhance relevant SN lensing, other physics such neutrino...
Abstract The climate crisis and the degradation of world's ecosystems require humanity to take immediate action. international scientific community has a responsibility limit negative environmental impacts basic research. HECAP+ communities ( High Energy Physics, Cosmology, Astroparticle Hadron Nuclear Physics ) make use common similar experimental infrastructure, such as accelerators observatories, rely similarly on processing big data. Our therefore face challenges improving sustainability...
GRavitational lEnsing Accuracy Testing 2010 (GREAT10) is a public image analysis challenge aimed at the development of algorithms to analyze astronomical images. Specifically, measure varying distortions in presence variable convolution kernel, pixelization and noise. This second series challenges set astronomy, computer science statistics communities, providing structured environment which methods can be improved tested preparation for planned surveys. GREAT10 extends upon previous work by...
We present the results from first public blind point-spread function (PSF) reconstruction challenge, GRavitational lEnsing Accuracy Testing 2010 (GREAT10) Star Challenge. Reconstruction of a spatially varying PSF, sparsely sampled by stars, at non-star positions is critical part in image analysis for weak lensing where inaccuracies modeled ellipticity e and size R2 can impact ability to measure shapes galaxies. This importance because particularly sensitive probe dark energy be used map mass...
Abstract We present optical follow-up imaging obtained with the Katzman Automatic Imaging Telescope, Las Cumbres Observatory Global Telescope Network, Nickel Swope and Thacher of LIGO/Virgo gravitational wave (GW) signal from neutron star–black hole (NSBH) merger GW190814. searched GW190814 localization region (19 deg 2 for 90th percentile best localization), covering a total 51 94.6% two-dimensional region. Analyzing properties 189 transients that we consider as candidate counterparts to...
We present the second public data release of Dark Energy Survey, DES DR2, based on optical/near-infrared imaging by Camera mounted 4-m Blanco telescope at Cerro Tololo Inter-American Observatory in Chile. DR2 consists reduced single-epoch and coadded images, a source catalog derived from associated products assembled 6 years science operations. This includes wide-area survey covering ~5000 deg2 southern Galactic cap five broad photometric bands, grizY. has median delivered point-spread...
Abstract We report the discovery and spectroscopic confirmation of quad-like lensed quasar system DES J0408-5354 found in Dark Energy Survey (DES) Year 1 (Y1) data. This was discovered during a search for Y1 strong lensing systems using method that identified candidates as red galaxies with multiple blue neighbors. consists central galaxy surrounded by three bright ( ) objects fourth object. Subsequent observations Gemini South telescope confirmed are indeed images redshift z = 2.375, object...
Binary black hole (BBH) mergers found by the LIGO and Virgo detectors are of immense scientific interest to astrophysics community, but considered unlikely be sources electromagnetic emission. To test whether they have rapidly fading optical counterparts, we used Dark Energy Camera perform an $i$-band search for BBH merger GW170814, first gravitational wave detected three interferometers. The 87-deg$^2$ localization region (at 90\% confidence) centered in Survey (DES) footprint enabled us...
Abstract On 2019 August 14 at 21:10:39 UTC, the LIGO/Virgo Collaboration (LVC) detected a possible neutron star–black hole merger (NSBH), first ever identified. An extensive search for an optical counterpart of this event, designated GW190814, was undertaken using Dark Energy Camera on 4 m Victor M. Blanco Telescope Cerro Tololo Inter-American Observatory. Target Opportunity interrupts were issued eight separate nights to observe 11 candidates 4.1 Southern Astrophysical Research (SOAR)...
We present gravitational lens models of the multiply imaged quasar DES J0408-5354, recently discovered in Dark Energy Survey (DES) footprint, with aim interpreting its remarkable quad-like configuration. first model single-epoch $grizY$ images as a superposition galaxy and four point-like objects, obtaining spectral energy distributions (SEDs) relative positions for objects. Three point sources (A,B,D) have SEDs compatible discovery spectra, while faintest image (G2/C) shows significant...
ABSTRACT We report the observation and confirmation of first group- cluster-scale strong gravitational lensing systems found in Dark Energy Survey data. Through visual inspection data from Science Verification season, we identified 53 candidate systems. then obtained spectroscopic follow-up 21 candidates using Gemini Multi-object Spectrograph at South telescope Inamori-Magellan Areal Camera Magellan/Baade telescope. With this follow-up, confirmed six as lenses: three are newly discovered,...
The Dark Energy Survey (DES) is an operating optical survey aimed at understanding the accelerating expansion of universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae. To perform 5000 sq-degree wide field 30 supernova surveys, DES Collaboration built Camera (DECam), a 3 square-degree, 570-Megapixel CCD camera that was installed prime focus Blanco 4-meter telescope Cerro Tololo Inter-American...