A5011104036- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Pulsars and Gravitational Waves Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Semiconductor materials and devices
- Ionosphere and magnetosphere dynamics
- Atmospheric Ozone and Climate
- Planetary Science and Exploration
- Advancements in PLL and VCO Technologies
- Photonic and Optical Devices
- Analog and Mixed-Signal Circuit Design
- Low-power high-performance VLSI design
- Radio Frequency Integrated Circuit Design
- Particle Accelerators and Free-Electron Lasers
- Spectroscopy and Laser Applications
- Optical Coatings and Gratings
- Geophysics and Sensor Technology
University of Toronto
2016-2025
Samsung (South Korea)
2002-2024
Yonsei University
2022
Canadian Institute for Theoretical Astrophysics
2007-2016
Korea Astronomy and Space Science Institute
2012-2014
California Institute of Technology
2004-2013
The University of Tokyo
2009
Seoul National University
1997-2009
UNSW Sydney
2009
San Diego State University
2007
We present detailed optical photometry for 25 Type Ibc supernovae (SNe Ibc) within d ≈ 150 Mpc obtained with the robotic Palomar 60 inch telescope in 2004–2007. This study represents first uniform, systematic, and statistical sample of multi-band SNe light curves available to date. correct host galaxy extinction using a new technique based on photometric color evolution, namely, we show that (V − R) extinction-corrected at Δt 10 days after V-band maximum is tightly distributed, 〈(V R)V10〉 =...
Type IIn supernovae (SNe IIn) are rare events, constituting only a few percent of all core-collapse SNe, and the current sample well-observed SNe is small. Here, we study four observed by Caltech Core-Collapse Project (CCCP). The CCCP SN unbiased to extent that object selection was not influenced target properties. Therefore, these events representative population IIn. We find narrow P-Cygni profile in hydrogen Balmer lines appears be ubiquitous feature Our light curves show relatively long...
We present a study of the Type IIn supernova (SN) 2005gl, in relatively nearby (d ≈ 66 Mpc) galaxy NGC 266. Photometry and spectroscopy SN indicate that it is typical member its class. Pre-explosion Hubble Space Telescope (HST) imaging location SN, along with precise localization this event using laser guide star assisted adaptive optics (LGS-AO) system at Keck Observatory, are combined to identify luminous (MV = -10.3 mag) point source as possible progenitor 2005gl. If indeed single star,...
We have converted the Palomar 60 inch (1.52 m) telescope from a classic night‐assistant‐operated to fully robotic facility. The automated system, which has been operational since 2004 September, is designed for moderately fast (t≲3 minutes) and sustained (R≲23 mag) observations of gamma‐ray burst afterglows other transient events. Routine queue‐scheduled can be interrupted in response electronic notification An pipeline reduces data real time, then stored on searchable Web‐based archive ease...
Four institutions are collaborating to design and build three near identical R ~2700 cross-dispersed near-infrared spectrographs for use on various 5-10 meter telescopes. The instrument addresses the common observatory need efficient, reliable through such features as broad wavelength coverage across 6 simultaneous orders (0.8 - 2.4 microns) in echelle format, real-time slit viewing separate optics detector, minimal moving parts. Lastly, collaborators saving money increasing likelihood of...
We present R-band light curves of Type II supernovae (SNe) from the Caltech Core-Collapse Project (CCCP). With exception interacting (Type IIn) SNe and rare events with long rise times, we find that most curve shapes belong to one three apparently distinct classes: plateau, slowly declining, rapidly declining events. The last class is composed solely IIb which similar those Ib, suggesting, perhaps, progenitor channels. do not any intermediate curves, implying these subclasses are unlikely...
We present multicolor optical observations of long-duration γ-ray bursts (GRBs) made over a three-year period with the robotic Palomar 60 inch telescope (P60). Our sample consists all 29 events discovered by Swift for which P60 began less than 1 hr after burst trigger. were able to recover 80% afterglows from this prompt sample, and we attribute high efficiency our red coverage. Like Melandri et al. (2008), find that significant fraction (≈50%) show suppression flux regard X-ray emission...
On 2006 May 5, a 4 s duration, low-energy, ~1049 erg, gamma-ray burst (GRB) was observed, spatially associated with z = 0.0894 galaxy. Here we report the discovery of GRB optical afterglow and observations its environment using Gemini South, Hubble Space Telescope (HST), Chandra, Swift, Very Large Array. The this is prominent star-forming region in Sc-type galaxy 2dFGRS S173Z112. Its proximity to suggests that progenitor delay time, from birth explosion, smaller than ~10 Myr. Our HST deep...
Long-duration gamma-ray bursts (GRBs) are widely believed to be highly-collimated explosions (opening angle theta ~ 1-10 deg). As a result of this beaming factor, the true energy release from GRB is usually several orders magnitude smaller than observed isotropic value. Measuring opening angle, typically inferred an achromatic steepening in afterglow light curve (a "jet" break), has proven exceedingly difficult Swift era. Here we undertake study five brightest (in terms prompt release,...
We present H-band observations of β Pic with the Gemini Planet Imager's (GPI's) polarimetry mode that reveal debris disk between ∼03 (6 AU) and ∼17 (33 AU), while simultaneously detecting b. The polarized image was fit a dust density model combined Henyey–Greenstein scattering phase function. best-fit indicates inclined to line sight () position angle (PA) (slightly offset from main outer disk, ), extends an inner radius well outside GPI's field view. In addition, we updated orbit for b...
We perform a systematic study of the $^{56}$Ni mass ($M_{\rm Ni}$) 27 stripped envelope supernovae (SESNe) by modeling their light-curve tails, highlighting that use ``Arnett's rule'' overestimates $M_{\rm Ni}$ for SESN factor $\sim$2. Recently, \citet{Khatami2019} presented new model relating peak time ($t_{\rm p}$) and luminosity ($L_{\rm radioactive-powered SN to its addresses several limitations Arnett-like models, but depends on dimensionless parameter, $β$. Using observed $t_{\rm p}$,...
We present optical, near-IR, and radio follow up of sixteen Swift bursts, including our discovery nine afterglows a redshift determination for three. These observations, supplemented by data from the literature, provide an afterglow recovery rate 60% in optical/near-IR, much higher than previous missions (BeppoSAX, HETE-2, INTEGRAL, IPN). The optical/near-IR events are on average 1.7 mag fainter at t=12 hr those missions. X-ray similarly compared to pre-Swift bursts. In limiting factor is...
We present observations of the unusually bright and long γ-ray burst GRB 050820A, one best sampled broadband data sets in Swift era. The light curve is marked by a soft precursor pulse some 200 s before main event; lack any intervening emission suggests that it due to physical mechanism distinct from itself. large time lag between enabled simultaneous γ-ray, X-ray, optical bandpasses, something only achieved for handful events date. While contemporaneous X-rays are low-energy tail prompt...
We report the performance of Triplespec from commissioning observations on 200-inch Hale Telescope at Palomar Observatory. is one a set three near-infrared, cross-dispersed spectrographs covering wavelengths 1 - 2.4 microns simultaneously resolution ~2700. At Palomar, uses 1×30 arcsecond slit. will be used for variety scientific observations, including moderate to high redshift galaxies, star formation, and low mass stars brown dwarfs. When in conjunction with an externally dispersed...
Phosphorus ($^{31}$P), which is essential for life, thought to be synthesized in massive stars and dispersed into interstellar space when these explode as supernovae (SNe). Here we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, show that abundance ratio phosphorus major nucleosynthetic product iron ($^{56}$Fe) material up 100 times average Milky Way, confirming produced SNe. The observed range compatible with predictions from models but not scenario...
We use new large area far infrared maps ranging from 65 to 500 μm obtained with the AKARI and Balloon-borne Large Aperture Submillimeter Telescope missions characterize dust emission toward Cassiopeia A supernova remnant (SNR). Using high-resolution data we find a "tepid" grain population at temperature of ∼35 K an estimated mass 0.06 M☉. This component is confined central SNR may represent newly formed in unshocked ejecta. While tepid that measure insufficient by itself account for observed...
We present H-band spectra of the candidate counterparts five ultraluminous X-ray sources (ULXs; two in NGC 925, 4136 and Holmberg II X-1) obtained with Keck/MOSFIRE (Multi-Object Spectrometer for Infra-Red Exploration). The ULXs (J022721+333500 925 J120922+295559 4136) have consistent (M-type) red supergiants (RSGs). epochs spectroscopy counterpart to J022721+333500, separated by 10 months, but discovered no radial velocity variations a 2σ upper limit 40 km s−1. If RSG is donor star ULX,...
Supernova (SN) 1987A was a peculiar H-rich event with long-rising (LR) light curve (LC), stemming from compact blue supergiant star (BSG). Only few similar events have been presented in the literature. We present new data for sample of 6 LR Type II SNe (SNe II), 3 which were discovered and observed by Palomar Transient Factory (PTF) Caltech Core-Collapse Project (CCCP). Our aim is to enlarge family II, characterizing their properties. Spectra, LCs, host-galaxies (HG) these are presented....
We present a wide-field optical imaging search for electromagnetic counterparts to the likely neutron star - black hole (NS-BH) merger GW190814/S190814bv. This compact binary was detected through gravitational waves by LIGO/Virgo interferometers, with masses suggestive of NS-BH merger. imaged localization region using MegaCam instrument on Canada-France-Hawaii Telescope. describe our hybrid observing strategy both tiling and galaxy-targeted observations, as well image differencing transient...