ORCID Profile
0000-0003-1349-6538
Current Organisation
The University of Texas at Austin
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Publisher: American Astronomical Society
Date: 16-10-2014
Publisher: Oxford University Press (OUP)
Date: 03-08-2021
Abstract: SN 2017jgh is a type IIb supernova discovered by Pan-STARRS during the C16/C17 c aigns of the Kepler/K2 mission. Here, we present the Kepler/K2 and ground based observations of SN 2017jgh, which captured the shock cooling of the progenitor shock breakout with an unprecedented cadence. This event presents a unique opportunity to investigate the progenitors of stripped envelope supernovae. By fitting analytical models to the SN 2017jgh light curve, we find that the progenitor of SN 2017jgh was likely a yellow supergiant with an envelope radius of $\\sim 50{\\!-\\!}290\\, {\\rm R}_{\\odot }$, and an envelope mass of $\\sim 0{\\!-\\!}1.7\\, {\\rm M}_{\\odot }$. SN 2017jgh likely had a shock velocity of ∼7500−10 300 km s−1. Additionally, we use the light curve of SN 2017jgh to investigate how early observations of the rise contribute to constraints on progenitor models. Fitting just the ground based observations, we find an envelope radius of $\\sim 50{\\!-\\!}330\\, {\\rm R}_{\\odot }$, an envelope mass of $\\sim 0.3{\\!-\\!}1.7\\, {\\rm M}_{\\odot }$ and a shock velocity of ∼9000−15 000 km s−1. Without the rise, the explosion time cannot be well constrained that leads to a systematic offset in the velocity parameter and larger uncertainties in the mass and radius. Therefore, it is likely that progenitor property estimates through these models may have larger systematic uncertainties than previously calculated.
Publisher: American Astronomical Society
Date: 07-2021
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We present the 30 minutes cadence Kepler/K2 light curve of the Type Ia supernova (SN Ia) SN 2018agk, covering approximately one week before explosion, the full rise phase, and the decline until 40 days after peak. We additionally present ground-based observations in multiple bands within the same time range, including the 1 day cadence DECam observations within the first ∼5 days after the first light. The Kepler early light curve is fully consistent with a single power-law rise, without evidence of any bump feature. We compare SN 2018agk with a s le of other SNe Ia without early excess flux from the literature. We find that SNe Ia without excess flux have slowly evolving early colors in a narrow range ( g − i ≈ −0.20 ± 0.20 mag) within the first ∼10 days. On the other hand, among SNe Ia detected with excess, SN 2017cbv and SN 2018oh tend to be bluer, while iPTF16abc’s evolution is similar to normal SNe Ia without excess in g − i . We further compare the Kepler light curve of SN 2018agk with companion-interaction models, and rule out the existence of a typical nondegenerate companion undergoing Roche lobe overflow at viewing angles smaller than 45°.
Publisher: American Astronomical Society
Date: 13-09-2018
Publisher: American Astronomical Society
Date: 28-12-2018
Publisher: Oxford University Press (OUP)
Date: 15-12-2017
Publisher: American Astronomical Society
Date: 19-11-2019
Publisher: American Astronomical Society
Date: 12-12-2014
Publisher: American Astronomical Society
Date: 22-06-2017
Publisher: American Astronomical Society
Date: 25-08-2023
Abstract: The LIGO HET Response (LIGHETR) project is an enterprise to follow up optical transients (OTs) discovered as gravitational-wave merger sources by the LIGO/Virgo collaboration (LVC). Early spectroscopy has the potential to constrain crucial parameters such as the aspect angle. The LIGHETR collaboration also includes the capacity to model the spectroscopic evolution of mergers to facilitate a real-time direct comparison of models with our data. The principal facility is the Hobby–Eberly Telescope. LIGHETR uses the massively replicated VIRUS array of spectrographs to search for associated OTs and obtain early blue spectra, and in a complementary role, the low-resolution LRS2 spectrograph is used to obtain spectra of viable candidates as well as a densely s led series of spectra of true counterparts. Once an OT is identified, the anticipated cadence of spectra would match or considerably exceed anything achieved for GW170817 = AT2017gfo for which there were no spectra in the first 12 hr and thereafter only roughly once daily. We describe special HET-specific software written to facilitate the program and attempts to determine the flux limits to undetected sources. We also describe our c aign to follow up OT candidates during the third observational c aign of the LIGO and Virgo Scientific Collaborations. We obtained VIRUS spectroscopy of candidate galaxy hosts for five LVC gravitational-wave events and LRS2 spectra of one candidate for the OT associated with S190901ap. We identified that candidate, ZTF19abvionh = AT2019pip, as a possible Wolf–Rayet star in an otherwise unrecognized nearby dwarf galaxy.
No related grants have been discovered for J. Craig Wheeler.