A5079737027- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Astrophysics and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Planetary Science and Exploration
- Radio Astronomy Observations and Technology
- Solar and Space Plasma Dynamics
- High-pressure geophysics and materials
- X-ray Spectroscopy and Fluorescence Analysis
- Geomagnetism and Paleomagnetism Studies
- Magnetic and Electromagnetic Effects
- Methane Hydrates and Related Phenomena
- Mechanical Engineering and Vibrations Research
- Statistical and numerical algorithms
- Astrophysics and Star Formation Studies
- Space Science and Extraterrestrial Life
- Optical Systems and Laser Technology
- Disaster Response and Management
Dickinson College
2011-2020
Roger Williams University
2013-2019
University of Maryland, College Park
2011-2014
Clemson University
2007-2012
Deleted Institution
2011-2012
Goddard Space Flight Center
2008-2011
Thüringer Landessternwarte Tautenburg
2009
Max Planck Institute for Extraterrestrial Physics
2009
Lawrence Livermore National Laboratory
2008
University of Arizona
2008
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...
Context. Thirteen years after the discovery of first afterglows, nature dark gamma-ray bursts (GRB) still eludes explanation: while each long-duration GRB typically has an X-ray afterglow, optical/NIR emission is only seen for 40–60% them.
(Abridged) Until recently the information inferred from gamma-ray burst follow-up observations was mostly limited to optically bright afterglows, biasing all demographic studies against sight-lines that contain large amounts of dust. Here, we present GRB afterglow and host for a sample bursts are exemplary previously missed ones because high visual extinction along sight-line. This facilitates an investigation properties, geometry location absorbing dust these poorly-explored galaxies,...
Fermi can measure the spectral properties of gamma-ray bursts over a very large energy range and is opening new window on prompt emission these energetic events. Localizations by instruments in combination with follow-up Swift provide accurate positions for observations at longer wavelengths leading to determination redshifts, true budget, host galaxy facilitate comparison pre-Fermi bursts. Multi-wavelength were performed afterglows four high detected Fermi/LAT : GRB090323, GRB090328,...
We report on the surprisingly high metallicity measured in two absorption systems at redshift, detected Very Large Telescope spectrum of afterglow gamma-ray burst GRB 090323. The systems, redshift z=3.5673 and z=3.5774 (separation Delta v ~ 660 km/s), are dominated by neutral gas interstellar medium parent galaxies. From singly ionized zinc sulfur, we estimate oversolar metallicities [Zn/H] =+0.29+/-0.10 [S/H] = +0.67+/- 0.34, blue red absorber, respectively. These highest ever galaxies z>3....
Observations of the gamma-ray sky with Fermi led to significant advances towards understanding blazars, most extreme class Active Galactic Nuclei. A large fraction population detected by is formed BL Lacertae (BL Lac) objects, whose sample has always suffered from a severe redshift incompleteness due quasi-featureless optical spectra. Our goal provide increase number confirmed high-redshift Lac objects contained in 2 LAC Fermi/LAT catalog. For 103 photometric redshifts using spectral energy...
We present a broadband study of gamma-ray burst (GRB) 091024A within the context other ultra-long-duration GRBs. An unusually long detected by Konus-Wind, Swift, and Fermi, GRB has prompt emission episodes covering ~1300 s, accompanied bright highly structured optical captured various rapid-response facilities, including 2-m autonomous robotic Faulkes North Liverpool Telescopes, KAIT, S-LOTIS, SRO. also observed with 8- 10-m class telescopes determine redshift to be z = 1.0924 \pm 0.0004....
We present a detailed study of the prompt and afterglow emission from Swift GRB 061126 using BAT, XRT, UVOT data multi-color optical imaging ten ground-based telescopes. was long burst (T_90=191 s) with four overlapping peaks in its gamma-ray light curve. The X-ray afterglow, observed 26 min to 20 days after burst, shows simple power-law decay alpha_X=1.290 \pm 0.008. Optical observations presented here cover time range 258 s (Faulkes Telescope North) 15 (Gemini burst; rate steep-to-shallow...
We present observations and analysis of the broadband afterglow Swift GRB 071025. Using optical infrared (RIYJHK) photometry, we derive a photometric redshift 4.4 < z 5.2; at this our simultaneous multicolour begin ~30 s after trigger in host frame during initial rising phase afterglow. associate light curve peak 580 observer with formation forward shock, giving an estimate Lorentz factor Gamma_0 ~ 200. The red spectral energy distribution (even regions not affected by Lyman-alpha break)...
Context: The link between the duration of GRBs and nature their progenitors remains disputed. Short bursts (with durations less than ~2 s) are frequently observed, technically more difficult to localize, exhibit significantly fainter afterglows. Aims: It is critical importance establish whether burst can reliably distinguish different GRB population models collapsars compact stellar mergers. Swift 090426 provides an unique opportunity address this question. Its (T_90=1.28 places firmly in...
Using high-quality, broad-band afterglow data for GRB 091127, we investigate the validity of synchrotron fireball model gamma-ray bursts, and infer physical parameters ultra-relativistic outflow. We used multi-wavelength follow-up observations obtained with GROND XRT onboard Swift satellite. The resulting light curve is excellent accuracy, spectral energy distribution well-sampled over 5 decades in energy. These present one most comprehensive observing campaigns a single allow us to test...
We present extensive optical and near-infrared photometric spectroscopic observations of the stripped-envelope (SE) supernova SN 2010as. Spectroscopic peculiarities, such as initially weak helium features low expansion velocities with a nearly flat evolution, place this object in small family events previously identified transitional Type Ib/c supernovae (SNe). There is ubiquitous evidence hydrogen, albeit weak, SNe, indicating that they are fact peculiar kind IIb SNe we name "flat-velocity...
Context . Gamma-ray bursts (GRBs) are ideal probes of the Universe at high redshift (ɀ), pinpointing locations earliest star-forming galaxies and providing bright backlights with simple featureless power-law spectra that can be used to spectrally fingerprint intergalactic medium host galaxy during period reionization. Future missions such as Gamow Explorer (hereafter Gamow) being proposed unlock this potential by increasing rate identification high-ɀ (ɀ > 5) GRBs in order rapidly trigger...
We present VLT/FORS2 spectroscopy and Gamma-ray Optical/Near-Infrared Detector optical/near-IR photometry of the afterglow bright Fermi/LAT GRB 090926A. The spectrum shows prominent Lyman-α absorption with cm−2 a multitude metal lines at common redshift z = 2.1062 ± 0.0004, which we associate gamma-ray burst (GRB). metallicity derived from S ii is log(Z/Z☉) ≈ −1.9, one lowest values ever found in Damped (DLA) system. This confirms that spread GRB-DLAs 2 least two orders magnitude. argue this...
We present a framework to obtain photometric redshifts (photo-zs) for gamma-ray burst afterglows. Using multi-band photometry from GROND and Swift/UVOT, photo-zs are derived five GRBs which spectroscopic not available. use UV/optical/NIR data synthetic based on afterglow observations theory derive the of their accuracy. Taking into account synchrotron emission properties, we investigate application in theoretical range between z~1 z~12. The measurement GRB afterglows provides quick, robust...
We present early-time optical through infrared photometry of the bright Swift gamma-ray burst (GRB) 080607, starting only 6 s following initial trigger in rest frame. Complemented by our previously published spectroscopy, this high-quality photometric data set allows us to solve for extinction properties redshift 3.036 sightline, giving perhaps most detailed information date on ultraviolet continuum absorption any sightline outside Local Group. The are not adequately modeled ordinary...
Context. After the launch of Swift satellite, Gamma-Ray Burst (GRB) optical light-curve smoothness paradigm has been questioned thanks to faster and better sampled follow-up, which unveiled a very complex behaviour. This complexity is triggering interest whole GRB community. The GROND multi-channel imager used study near-infrared (NIR) afterglows GRBs with unprecedented temporal spectral resolution. 081029 prominent rebrightening event an outstanding example application afterglows. Aims....
We present the results of a comprehensive study gamma-ray burst 080928 and its afterglow. GRB was long detected by Swift/BAT Fermi/GBM. It is one exceptional cases where optical emission had already been when itself still radiating in band. For nearly 100 s simultaneous optical, X-ray data provide coverage spectral energy distribution transient source from about 1 eV to 150 keV. In particular, we show that SED during main prompt phase agrees with synchrotron radiation. constructed...
We report on follow-up observations of 20 short-duration gamma-ray bursts performed in g'r'i'z'JHKs with the seven-channel imager GROND between mid-2007 and end 2010. This is one most comprehensive data sets GRB afterglow short published so far. In three cases was target within less than 10 min after trigger, leading to discovery 081226A its faint underlying host galaxy. addition, able image optical follow light-curve evolution further five cases, GRBs 090305, 090426, 090510, 090927,...
(...) Since 1998, only half a dozen spectroscopically confirmed associations have been discovered and XRF 100316D associated with the type-Ic SN 2010bh at z = 0.059 is among latest. We began observations GROND 12 hours after GRB trigger continued until 80 days burst. provided excellent photometric data in six filter bands covering wavelength range from approx. 350 to 1800 nm, significantly expanding pre-existing set for this event. Combining Swift data, early broad-band SED modelled...
GRB 111209A, one of the longest Gamma-Ray Bursts (GRBs) ever observed, is linked to SN 2011kl, most luminous GRB-Supernova (SN) detected so far, which shows evidence for being powered by a magnetar central engine. We place 2011kl into context large samples SNe, addressing in more detail question whether it could be radioactively powered, and represents an extreme version GRB-SN or underluminous Superluminous (SLSN). model using 1998bw as template derive bolometric light curve including...
<i>Aims. <i/>We investigate the optical/near-infrared light curve of afterglow GRB 080710 in context rising afterglows.<i>Methods. <i/>Optical and near-infrared photometry was performed using seven-channel imager GROND Tautenburg Schmidt telescope. X-ray data were provided by Telescope onboard <i>Swift<i/> satellite. We construct an empirical model available broadband data, which is well-sampled time frequency domains.<i>Results. <i/>The optical/NIR dominated initial increase brightness,...
Two types of dust disks around white dwarfs (WDs) have been reported: small cool metal-rich WDs consisting tidally disrupted asteroids and a large disk the hot central WD Helix planetary nebula (PN) possibly produced by collisions among Kuiper-Belt-like objects. To search for more latter type, we conducted Spitzer MIPS 24 μm survey 71 or pre-WDs, which 35 are stars PNe (CSPNs). Nine these evolved detected their flux densities at least two orders magnitude higher than expected photospheric...