D. Reichart
A5005867611- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Radio Astronomy Observations and Technology
- Planetary Science and Exploration
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Medical Imaging Techniques and Applications
- High-pressure geophysics and materials
- Usability and User Interface Design
- Neutrino Physics Research
- Particle Accelerators and Free-Electron Lasers
- History and Developments in Astronomy
- Adaptive optics and wavefront sensing
- Gyrotron and Vacuum Electronics Research
- Atmospheric Ozone and Climate
- Nuclear Physics and Applications
University of North Carolina at Chapel Hill
2016-2025
Lowell Observatory
2015
Astronomy and Space
2010
Bowling Green State University
2010
Space Telescope Science Institute
2009
University of Hawaii System
2009
University of Baltimore
2009
Johns Hopkins University
2009
University of Leicester
2009
University of Warwick
2009
We present a comprehensive sample of all gamma-ray burst (GRB) afterglows with known distances, and we derive their conical opening angles based on observed broadband breaks in light curves. Within the framework this jet model, correct for geometry find that energy release is narrowly clustered around 5 × 1050 ergs. draw three conclusions. First, central engines GRBs energies are comparable to ordinary supernovae. Second, broad distribution fluence luminosity largely result wide variation...
We describe the target selection and resulting properties of a spectroscopic sample luminous red galaxies (LRGs) from imaging data Sloan Digital Sky Survey (SDSS). These are selected on basis color magnitude to yield intrinsically that extends fainter farther than main flux-limited portion SDSS galaxy sample. The is designed impose passively evolving luminosity rest-frame cut redshift 0.38. Additional, yet more included ∼0.5. Approximately 12 these per square degree targeted for...
We describe observed properties of the Type Iax class supernovae (SNe Iax), consisting SNe observationally similar to its prototypical member, SN 2002cx. The currently has 25 members, and we present optical photometry and/or spectroscopy for most them. are spectroscopically Ia, but have lower maximum-light velocities (2000 ≲ |v| 8000 km s−1), typically peak magnitudes (−14.2 ⩾ MV, ≳ −18.9 mag), hot photospheres. Relative low luminosities their light-curve shape. There is a correlation...
We report the results of a three-year-long dedicated monitoring campaign restless luminous blue variable (LBV) in NGC 7259. The object, named SN 2009ip, was observed photometrically and spectroscopically optical near-infrared domains. monitored number erupting episodes past few years, increased density our observations during eruptive episodes. In this paper, we present full historical data set from 2009 to 2012 with multi-wavelength dense coverage two high-luminosity events between August...
During the second observing run of Laser Interferometer gravitational- wave Observatory (LIGO) and Virgo Interferometer, a gravitational-wave signal consistent with binary neutron star coalescence was detected on 2017 August 17th (GW170817), quickly followed by coincident short gamma-ray burst trigger Fermi satellite. The Distance Less Than 40 (DLT40) Mpc supernova search performed pointed follow-up observations sample galaxies regularly monitored survey which fell within combined LIGO+Virgo...
Abstract We present the optical spectroscopic evolution of SN 2023ixf seen in subnight cadence spectra from 1.18 to 15 days after explosion. identify high-ionization emission features, signatures interaction with material surrounding progenitor star, that fade over first 7 days, rapid between observed within same night. compare lines and their relative strength those other supernovae early interaction, finding a close match 2020pni 2017ahn spectrum 2014G at later epochs. To physically...
Abstract We present the densely sampled early light curve of Type II supernova (SN) 2023ixf, first observed within hours explosion in nearby Pinwheel Galaxy (Messier 101; 6.7 Mpc). Comparing these data to recently updated models shock-cooling emission, we find that progenitor likely had a radius 410 ± 10 R ⊙ . Our estimate is model dependent but consistent with red supergiant. These provide good fit starting about 1 day after explosion, despite fact classification spectrum shows signatures...
The recent evidence that the light curves and spectra of afterglows GRB 970228 980326 appear to contain a SN component, in addition relativistic shock wave provide direct clues at least long GRBs detected by BeppoSAX are result collapse massive stars. We show that, if this is indeed case, their powerful probe very high redshift (VHR) (z > 5) universe. first establish both detectable out VHRs. then one expects occur z ~ 10 possibly \~ 15 - 20, redshifts far larger than those expected for most...
We present a possible Cepheid-like luminosity estimator for the long gamma-ray bursts based on variability of their light curves. To construct estimator, we use CGRO/BATSE data 13 bursts, Wind/Konus five Ulysses/GRB one burst, and NEAR/XGRS burst. Spectroscopic redshifts, peak fluxes, high-resolution curves are available 11 these bursts; partial information is remaining nine bursts. find that isotropic equivalent luminosities L positively correlate with rigorously constructed measure V fit...
We present the C4 Cluster Catalog, a new sample of 748 clusters galaxies identified in spectroscopic Second Data Release (DR2) Sloan Digital Sky Survey (SDSS). The cluster-finding algorithm identifies as overdensities seven-dimensional position and color space, thus minimizing projection effects that have plagued previous optical cluster selection. catalog covers ∼2600 deg2 sky ranges redshift from z = 0.02 to 0.17. mean membership is 36 (with measured redshifts) brighter than r 17.7, but...
We present broadband (radio, optical, and X-ray) light curves spectra of the afterglows four long-duration gamma-ray bursts (GRBs; GRBs 090323, 090328, 090902B, 090926A) detected by Gamma-Ray Burst Monitor Large Area Telescope (LAT) instruments on Fermi satellite. With its wide spectral bandpass, extending to GeV energies, is sensitive with very large isotropic energy releases (1054 erg). Although rare, these events are particularly important for testing GRB central-engine models. When...
ABSTRACT OJ 287 is a quasi-periodic quasar with roughly 12 year optical cycles. It displays prominent outbursts that are predictable in binary black hole model. The model predicted major outburst 2015 December. We found the did occur within expected time range, peaking on December 5 at magnitude 12.9 R -band. Based Swift /XRT satellite measurements and polarization data, we find it included thermal component. Its timing provides an accurate estimate for spin of primary hole, . present also...
We present ultraviolet, optical and near-infrared observations of the interacting transient SN 2009ip, covering period from start outburst in 2012 October until end observing season. The reached a peak magnitude MV = −17.7 mag, with total integrated luminosity 1.9 × 1049 erg over August–December. light curve fades rapidly, dropping by 4.5 mag V-band 100 d. spectra are dominated narrow emission lines broad electron scattering wings, signalling dense circumstellar environment, together...
We present observations and analysis of 18 stripped-envelope supernovae observed during 2013–2018. This sample consists five H/He-rich SNe, six H-poor/He-rich three narrow lined SNe Ic, four broad Ic. The peak luminosity characteristic time-scales the bolometric light curves are calculated, modelled to derive 56Ni ejecta masses (MNi Mej). Additionally, temperature evolution spectral line velocity each SN examined. Analysis [O i] in nebular phase eight suggests their progenitors had initial...
We present X-ray and radio observations of the Fast Blue Optical Transient (FBOT) CRTS-CSS161010 J045834-081803 (CSS161010 hereafter) at t=69-531 days. CSS161010 shows luminous ($L_x\sim5\times 10^{39}\,\rm{erg\,s^{-1}}$) ($L_{\nu}\sim10^{29}\,\rm{erg\,s^{-1}Hz^{-1}}$) emission. The emission peaked ~100 days post transient explosion rapidly decayed. interpret these in context synchrotron from an expanding blastwave. launched a mildly relativistic outflow with velocity $\Gamma\beta c\ge0.55c$...
Abstract Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission gravitational waves (GWs). We show that observations associated binary black hole (BBH) central engine blazar OJ 287 demand inclusion radiation reaction effects beyond quadrupolar order. It turns out even certain hereditary contributions to GW required predict impact flare timings 287. develop an approach incorporates this effect into BBH...
Abstract On 2019 April 25.346 and 26.640 UT the Laser Interferometer Gravitational-Wave Observatory (LIGO) Virgo gravitational-wave (GW) observatory announced detection of first candidate events in Observing Run 3 that contained at least one neutron star (NS). S190425z is a likely binary (BNS) merger d L = 156 ± 41 Mpc, while S190426c possibly NS–black hole (BH) ever detected, 377 100 although with marginal statistical significance. Here we report our optical follow-up observations for both...
We report on the masses ($M_\mathrm{WD}$), effective temperatures ($T_\mathrm{eff}$) and secular mean accretion rates ($\langle \dot{M} \rangle$) of 43 cataclysmic variable (CV) white dwarfs, 42 which were obtained from combined analysis their $\mathit{Hubble~Space~Telescope}$ ultraviolet data with parallaxes provided by Early Third Data Release $\mathit{Gaia}$ space mission, one dwarf gravitational redshift. Our results double number CV dwarfs an accurate mass measurement, bringing total...
At the time of its discovery, optical and X-ray afterglow GRB 970228 appeared to be a ringing endorsement previously untried relativistic fireball model gamma-ray burst (GRB) afterglows, but now that nearly dozen afterglows GRBs have been observed, wavering light curve reddening spectrum this make it perhaps most difficult observed reconcile with model. In Letter, we argue afterglow's unusual temporal spectral properties can attributed supernova overtook 2 weeks after GRB. This is strongest...
Using observations from an extensive monitoring campaign with the Hubble Space Telescope, we present detection of intermediate-time flux excess that is redder in color relative to afterglow GRB 011121, currently distinguished as gamma-ray burst lowest known redshift. The red "bump," which exhibits a spectral rollover at ~7200 Å, well described by redshifted Type Ic supernova occurred approximately same time event. inferred luminosity about half bright SN 1998bw. These results serve...
Ultraviolet, optical, and near-infrared photometry optical spectroscopy of the broad-lined Type Ic supernova (SN) 2009bb are presented, following flux evolution from −10 to +285 days past B-band maximum. Thanks very early discovery, it is possible place tight constraints on SN explosion epoch. The expansion velocities measured near maximum spectra found be only slightly smaller than those prototype 1998bw associated with GRB 980425. Fitting an analytical model pseudobolometric light curve...