A5013376683- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Spectroscopy and Chemometric Analyses
- Adaptive optics and wavefront sensing
- Particle Detector Development and Performance
- Galaxies: Formation, Evolution, Phenomena
- CCD and CMOS Imaging Sensors
- Nuclear Physics and Applications
- Computational Physics and Python Applications
- Solar and Space Plasma Dynamics
- Planetary Science and Exploration
- Calibration and Measurement Techniques
- Advanced Computational Techniques and Applications
- Astrophysics and Star Formation Studies
- Particle Accelerators and Free-Electron Lasers
- Geophysics and Gravity Measurements
- Statistical and numerical algorithms
- Spacecraft Design and Technology
Arizona State University
2015-2024
Earth and Space Research
2014
Albert Einstein College of Medicine
2013
University of California, Berkeley
2006-2012
The University of Tokyo
2012
Alfred P. Sloan Foundation
2011
Berkeley College
2009-2010
Vassar College
2002-2008
Campbell Collaboration
2008
University of Chicago
1911-2007
The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA launch in 2017 as an Astrophysics Explorer mission. spacecraft be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with I = 4-13 temporary drops brightness caused planetary transits. Each star observed interval...
The Transiting Exoplanet Survey Satellite (TESS ) will search for planets transiting bright and nearby stars. TESS has been selected by NASA launch in 2017 as an Astrophysics Explorer mission. spacecraft be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with I<sub>C</sub> (approximately less than) 13 temporary drops brightness caused planetary...
While gas accretion onto some massive black holes (MBHs) at the centers of galaxies actively powers luminous emission, vast majority MBHs are considered dormant. Occasionally, a star passing too near MBH is torn apart by gravitational forces, leading to bright panchromatic tidal disruption flare (TDF). high-energy transient Swift J164449.3+573451 ("Sw 1644+57") initially displayed none theoretically anticipated (nor previously observed) TDF characteristics, we show that observations (Levan...
We report the discovery by Swift hard X-ray monitor of transient source J2058.4+0516 (Sw J2058+05). Our multi-wavelength follow-up campaign uncovered a long-lived (duration ≳ months), luminous (LX, iso ≈ 3 × 1047 erg s−1) and radio (νLν, 1042 counterpart. The associated optical emission, however, from which we measure redshift 1.1853, is relatively faint, this not due to large amount dust extinction in host galaxy. Based on numerous similarities with recently discovered GRB 110328A/Swift...
Variable X-ray and gamma-ray emission is characteristic of the most extreme physical processes in Universe, studying sources these energetic photons has been a major driver astronomy for past 50 years. Here we present multiwavelength observations unique selected transient, discovered by Swift, which was accompanied bright across electromagnetic spectrum, whose properties are unlike any previously observed source. We pinpoint event to center small, star-forming galaxy at redshift z=0.3534....
We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to September 2009, for total 76 GRBs, and present an additional three pre-Swift not included in earlier sample. Furthermore, we publish 840 new points 42 GRB afterglows, sets 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A 080810. analyzed light curves all derived spectral energy distributions with best quality, allowing us estimate host...
We present 2,241 exoplanet candidates identified with data from the Transiting Exoplanet Survey Satellite (TESS) during its two-year prime mission. list these in TESS Objects of Interest (TOI) Catalog, which includes both new planet found by and previously-known planets recovered observations. describe process used to identify TOIs investigate characteristics candidates, discuss some notable discoveries. The TOI Catalog an unprecedented number small around nearby bright stars, are...
Gamma-ray bursts (GRBs) have been separated into two classes, originally along the lines of duration and spectral properties, called "short/hard" "long/soft." The latter conclusively linked to explosive deaths massive stars, while former are thought result from merger or collapse compact objects. In recent years, indications accumulating that short/hard versus long/soft division does not map directly onto what would be expected classes progenitors, leading a new classification scheme Type I...
Wide-field optical surveys have begun to uncover large samples of fast (trise ≲ 5 d), luminous (Mpeak < −18), blue transients. While commonly attributed the breakout a supernova shock into dense wind, great distances transients this class found so far hampered detailed investigation their properties. We present photometry and spectroscopy from comprehensive worldwide campaign observe AT 2018cow (ATLAS 18qqn), first fast-luminous transient be in real time at low redshift. Our spectra (<2 days...
Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts long (>2 s) duration produced by the core-collapse massive stars, those short (< 2 merger two neutron stars (NSs). A third class events with hybrid properties was identified, but never conclusively linked to a stellar progenitor. The lack bright supernovae rules out typical explosions, their distance scales prevent sensitive searches for direct signatures progenitor system. Only...
Long-duration gamma-ray bursts (GRBs) are powerful cosmic explosions, signaling the death of massive stars. Among them, GRB 221009A is by far brightest burst ever observed. Because its enormous energy (Eiso ≈ 1055 erg) and proximity (z 0.15), an exceptionally rare event that pushes limits our theories. We present multiwavelength observations covering first 3 months afterglow evolution. The x-ray brightness decays as a power law with slope ≈t-1.66, which not consistent standard predictions...
We calculate durations and spectral parameters for 218 Swift bursts detected by the BAT instrument between including gamma-ray (GRBs) 041220 070509, 77 events with measured redshifts. Incorporating prior knowledge into fits, we are able to measure characteristic νFν peak energy Epk, obs isotropic equivalent Eiso (1-104 keV) all events. This complete rather extensive catalog, analyzed a unified methodology, allows us address persistence origin of high-energy correlations suggested in...
With the coming data deluge from synoptic surveys, there is a growing need for frameworks that can quickly and automatically produce calibrated classification probabilities newly-observed variables based on small number of time-series measurements. In this paper, we introduce methodology variable-star classification, drawing modern machine-learning techniques. We describe how to homogenize information gleaned light curves by selection computation real-numbered metrics ("feature"), detail...
We describe and discuss the global properties of 45 gamma-ray bursts (GRBs) observed by HETE-2 during first 3 years its mission, focusing on X-ray flashes (XRFs) X-ray-rich GRBs (XRRs). find that numbers XRFs, XRRs, are comparable, durations sky distributions XRFs XRRs similar to those GRBs. also spectral GRBs, except values peak energy E burst spectrum in νFν, flux Fpeak, fluence SE much smaller (and smaller) than Finally, we all three kinds form a continuum [SE(2-30 keV), SE(30-400) keV]...
While a white dwarf is, from theoretical perspective, the most plausible primary star in Type Ia supernova (SN Ia), many other candidates have not been formally ruled out. Shock energy deposited envelope of any exploding contributes to early SN brightness and, since this radiation is degraded by expansion after explosion, diffusive luminosity depends on initial radius. We present new non-detection limit nearby 2011fe, obtained what appears be just 4 hours allowing us directly constrain...
We present extensive early photometric (ultraviolet through near-infrared) and spectroscopic (optical data on supernova (SN) 2008D as well X-ray analysis the associated Swift transient (XRT) 080109. Our span a time range of 5 hr before detection to 150 days after its detection, detailed allowed us derive constraints nature SN progenitor; throughout we draw comparisons with results presented in literature find several key aspects that differ. show spectrum XRT 080109 can be fit equally by an...
We report on observations of GRB 080503, a short gamma-ray burst (GRB) with very bright extended emission (about 30 times the fluence initial spike) in conjunction thorough comparison to other Swift events. In spite prompt-emission brightness, however, optical counterpart is extraordinarily faint, never exceeding 25 mag deep starting at ∼1 hr after Burst Alert Telescope (BAT) trigger. The brightness peaks day and then falls sharply manner similar predictions Li & Paczyński (1998) for...
In this work, we present the first results of our imaging campaign at Keck Observatory to identify host galaxies "dark" gamma-ray bursts (GRBs), events with no detected optical afterglow or flux significantly fainter than expected from observed X-ray afterglow. We find that out a uniform sample 29 Swift rapidly by Palomar 60 inch telescope through 2008 March (14 which classify as dark), all have either afterglow, probable host-galaxy detection, both. Our constrain fraction GRBs coming very...
We calculate durations and spectral parameters for 207 Swift bursts detected by the BAT instrument from April 2007 to August 2009, including 67 events with measured redshifts. This is first supplement our catalog of 425 GRBs (147 redshifts) starting GRB041220. complete extensive data set, analyzed a unified methodology, allows us conduct an accurate census intrinsic GRB energetics, hardnesses, durations, The world model we derive reproduces well observables both pre-Swift satellites....
The rate of image acquisition in modern synoptic imaging surveys has already begun to outpace the feasibility keeping astronomers real-time discovery and classification loop. Here we present inner workings a framework, based on machine-learning algorithms, that captures expert training ground-truth knowledge about variable transient sky automate 1) process differences and, 2) generation preliminary science-type classifications discovered sources. Since follow-up resources for extracting...
In the epoch of precise and accurate cosmology, cross-confirmation using a variety cosmographic methods is paramount to circumvent systematic uncertainties. Owing progenitor histories explosion physics differing from those Type Ia supernovae (SNe Ia), II-plateau II-P) are unlikely be affected by evolution in same way. Based on new analysis 17 SNe II-P, an improved methodology, we find that II-P good standardizable candles, almost comparable Ia. We derive tight Hubble diagram with dispersion...
We report on our early photometric and spectroscopic observations of the extremely luminous Type II supernova (SN) 2008es. SN 2008es, with an observed peak optical magnitude mV = 17.8 at a redshift z 0.213, has absolute MV −22.3, making it second most ever observed. The evolution 2008es exhibits fast decline rate (∼ 0.042 mag d−1), similar to II-Linear (II-L) 2005ap. show that spectroscopically resembles II-L 1979C. Although spectra lack narrow intermediate-width line emission typically...