Gautham Narayan
A5003296263- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Integrated Circuits and Semiconductor Failure Analysis
- Scientific Computing and Data Management
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Adaptive optics and wavefront sensing
- Calibration and Measurement Techniques
- Solar and Space Plasma Dynamics
- Superconducting Materials and Applications
- Anomaly Detection Techniques and Applications
- Planetary Science and Exploration
- Spacecraft and Cryogenic Technologies
- Time Series Analysis and Forecasting
- Particle Detector Development and Performance
- CCD and CMOS Imaging Sensors
- Geophysics and Gravity Measurements
- Distributed and Parallel Computing Systems
University of Illinois Urbana-Champaign
2019-2024
National Center for Supercomputing Applications
2020-2024
Space Telescope Science Institute
2017-2023
KLE Technological University
2023
Brookhaven National Laboratory
2015-2022
University of Illinois System
2022
Astronomy and Space
2020
National Institute of Technology Karnataka
2020
Michigan Science Center
2019
Kitt Peak National Observatory
2014-2019
We present optical light curves, redshifts, and classifications for 365 spectroscopically confirmed Type Ia supernovae (SNe Ia) discovered by the Pan-STARRS1 (PS1) Medium Deep Survey. detail improvements to PS1 SN photometry, astrometry calibration that reduce systematic uncertainties in distances. combine subset of 279 ($0.03 < z 0.68$) with useful distance estimates from SDSS, SNLS, various low-z HST samples form largest combined sample consisting a total 1048 ranging $0.01 2.3$, which we...
Pan-STARRS1 has carried out a set of distinct synoptic imaging sky surveys including the $3π$ Steradian Survey and Medium Deep in 5 bands ($grizy_{P1}$). The mean 5$σ$ point source limiting sensitivities stacked 3$π$ $grizy_{P1}$ are (23.3, 23.2, 23.1, 22.3, 21.4) respectively. upper bound on systematic uncertainty photometric calibration across is 7-12 millimag depending bandpass. astrometric using Gaia frame comes from comparison results with Gaia: standard deviation median residuals ($...
We present constraints on the dark energy equation-of-state parameter, w=P/(rho c^2), using 60 Type Ia supernovae (SNe Ia) from ESSENCE supernova survey. derive a set of nature assuming flat Universe. By including (Omega_M, w) baryon acoustic oscillations, we obtain value for static parameter w=-1.05^{+0.13}_{-0.12} (stat; 1 sigma) +- 0.11 (sys) and Omega_M=0.274^{+0.033}_{-0.020} with best-fit chi^2/DoF 0.96. These results are consistent those reported by SuperNova Legacy Survey in similar...
We present multiband photometry of 185 type-Ia supernovae (SNe Ia), with over 11,500 observations. These were acquired between 2001 and 2008 at the F. L. Whipple Observatory Harvard-Smithsonian Center for Astrophysics (CfA). This sample contains largest number homogeneously observed reduced nearby SNe Ia (z ≲ 0.08) published to date. It more than doubles sample, bringing SN cosmology point where systematic uncertainties dominate. Our natural system has a precision ≲0.02 mag in BVRIr'i' ≲0.04...
In the past decade, several rapidly evolving transients have been discovered whose timescales and luminosities are not easily explained by traditional supernovae (SNe) models. The sample size of these objects has remained small due, at least in part, to challenges detecting short timescale with survey cadences. Here we present results from a search within Pan-STARRS1 Medium Deep Survey (PS1-MDS) for luminous transients. We identify 10 new time above half-maximum (t1/2) less than 12 days...
This paper describes the organization of database and catalog data products from Pan-STARRS1 $3\pi$ Steradian Survey. The are available in form an SQL-based relational MAST, Mikulski Archive for Space Telescopes at STScI. is described detail, including construction database, provenance data, schema, how tables related. Examples queries a range science goals included.
We present optical spectroscopy and optical/near-IR photometry of 31 host galaxies hydrogen-poor superluminous supernovae (SLSNe), including 15 events from the Pan-STARRS1 Medium Deep Survey. Our sample spans redshift range 0.1 ≲ z 1.6, is first comprehensive galaxy study this specific subclass cosmic explosions. Combining multi-band emission-line measurements, we determine luminosities, stellar masses, star formation rates, metallicities. find that, as a whole, hosts SLSNe are...
We present griz light curves of 146 spectroscopically confirmed Type Ia Supernovae ($0.03 < z <0.65$) discovered during the first 1.5 years Pan-STARRS1 Medium Deep Survey. The natural photometric system is determined by a combination on-site measurements instrument response function and observations spectrophotometric standard stars. find that systematic uncertainties in are currently 1.2\% without accounting for uncertainty HST Calspec definition AB system. A Hubble diagram constructed with...
Much of the progress made in time-domain astronomy is accomplished by relating observational multi-wavelength time series data to models derived from our understanding physical laws. This goal typically dividing task two: collecting (observing), and constructing represent that (theorizing). Owing natural tendency for specialization, a disconnect can develop between best available theories data, potentially delaying advances new classes transients. We introduce MOSFiT: Modular Open-Source...
We describe the implementation and optimization of ESSENCE supernova survey, which we have undertaken to measure equation state parameter dark energy. present a method for optimizing survey exposure times cadence maximize our sensitivity energy w=P/rho c^2 given fixed amount telescope time. For on CTIO 4m telescope, measuring luminosity distances redshifts supernovae at modest (z~0.5 +- 0.2) is optimal determining w. data analysis pipeline based using reliable robust image subtraction find...
We present the Pan-STARRS1 discovery of long-lived and blue transient PS1-11af, which was also detected by Galaxy Evolution Explorer with coordinated observations in near-ultraviolet (NUV) band. PS1-11af is associated nucleus an early type galaxy at redshift z = 0.4046 that exhibits no evidence for star formation or active galactic activity. Four epochs spectroscopy reveal a pair broad absorption features UV on otherwise featureless spectra. Despite superficial similarity these to P-Cygni...
We present multi-band optical photometry of 94 spectroscopically confirmed Type Ia supernovae (SNe Ia) in the redshift range 0.0055–0.073, obtained between 2006 and 2011. There are a total 5522 light-curve points. show that our natural-system SN has precision ≲ 0.03 mag BVr'i', 0.06 u', 0.07 U for points brighter than 17.5 estimate it systematic uncertainty 0.014, 0.010, 0.012, 0.046, 0.073 BVr'i'u'U, respectively. Comparisons standard-system with published light curves comparison stars...
We present the discovery of two ultra-luminous supernovae (SNe) at z ~ 0.9 with Pan-STARRS1 Medium-Deep Survey. These SNe, PS1-10ky and PS1-10awh, are amongst most luminous SNe ever discovered, comparable to unusual transients SN 2005ap SCP 06F6. Like 06F6, they show characteristic high luminosities (M_bol -22.5 mag), blue spectra a few broad absorption lines, no evidence for H or He. have constructed full multi-color light curve sensitive peak spectral energy distribution in rest-frame...
We have constructed a comprehensive statistical model for Type Ia supernova (SN Ia) light curves spanning optical through near-infrared (NIR) data. A hierarchical framework coherently models multiple random and uncertain effects, including intrinsic (SN) curve covariances, dust extinction reddening, distances. An improved BayeSN Markov Chain Monte Carlo code computes probabilistic inferences the by sampling global probability density of parameters describing individual SNe population....
In recent years, wide-field sky surveys providing deep multi-band imaging have presented a new path for indirectly characterizing the progenitor populations of core-collapse supernovae (SN): systematic light curve studies. We assemble set 76 grizy-band Type IIP SN curves from Pan-STARRS1, obtained over constant survey program 4 years and classified using both spectroscopy machine learning-based photometric techniques. develop apply Bayesian model full evolution each in sample. find no...
We present RAPID (Real-time Automated Photometric IDentification), a novel time-series classification tool capable of automatically identifying transients from within day the initial alert, to full lifetime light curve. Using deep recurrent neural network with Gated Recurrent Units (GRUs), we first method specifically designed provide early classifications astronomical data, typing 12 different transient classes. Our classifier can process curves any phase coverage, and it does not rely on...
We probe the systematic uncertainties from 113 Type Ia supernovae (SNIa) in Pan-STARRS1 (PS1) sample along with 197 SN a combination of low-redshift surveys. The companion paper by Rest et al. (2013) describes photometric measurements and cosmological inferences PS1 sample. largest uncertainty stems calibration low-z samples. increase observed Calspec standards 7 to 10 used define system. SDSS-II systems are compared discrepancies up ~0.02 mag recovered. find proper way treat intrinsic...
The unprecedented volume and rate of transient events that will be discovered by the Large Synoptic Survey Telescope (LSST) demands astronomical community update its followup paradigm. Alert-brokers -- automated software system to sift through, characterize, annotate prioritize for critical tools managing alert streams in LSST era. Arizona-NOAO Temporal Analysis Response Events System (ANTARES) is one such broker. In this work, we develop a machine learning pipeline characterize classify...
Time domain science has undergone a revolution over the past decade, with tens of thousands new supernovae (SNe) discovered each year. However, several observational domains, including SNe within days or hours explosion and faint, red transients, are just beginning to be explored. Here, we present Young Supernova Experiment (YSE), novel optical time-domain survey on Pan-STARRS telescopes. Our is designed obtain well-sampled $griz$ light curves for transient events up $z \approx 0.2$. This...
We present the Young Supernova Experiment Data Release 1 (YSE DR1), comprised of processed multi-color Pan-STARRS1 (PS1) griz and Zwicky Transient Facility (ZTF) gr photometry 1975 transients with host-galaxy associations, redshifts, spectroscopic/photometric classifications, additional data products from 2019 November 24 to 2021 December 20. YSE DR1 spans discoveries observations young fast-rising supernovae (SNe) that persist for over a year, redshift distribution reaching z~0.5. relative...
We present extensive optical photometry of the afterglow GRB~221009A. Our data cover $0.9 - 59.9$\,days from time \textit{Swift} and \textit{Fermi} GRB detections. Photometry in $rizy$-band filters was collected primarily with Pan-STARRS supplemented by multiple 1- to 4-meter imaging facilities. analyzed Swift X-ray found a single decline rate power-law $f(t) \propto t^{-1.556\pm0.002}$ best describes light curve. In addition high foreground Milky Way dust extinction along this line sight,...
Abstract Next-generation surveys like the Legacy Survey of Space and Time (LSST) on Vera C. Rubin Observatory (Rubin) will generate orders magnitude more discoveries transients variable stars than previous surveys. To prepare for this data deluge, we developed Photometric LSST Astronomical Time-series Classification Challenge (PLAsTiCC), a competition that aimed to catalyze development robust classifiers under LSST-like conditions nonrepresentative training set large photometric test...