Related papers: Exploring dust extinction at the edge of reionizat…

Dark gamma-ray bursts (GRBs) are sources with a low optical-to-X-ray flux ratio. Proposed explanations for this darkness are: i) the GRB is at high redshift ii) dust in the GRB host galaxy absorbs the optical/NIR flux iii) GRBs have an…

We present optical, near-infrared, and radio observations of the afterglow of GRB 120521C. By modeling the multi-wavelength dataset, we derive a photometric redshift of z~6.0, which we confirm with a low signal-to-noise ratio spectrum of…

High-redshift gamma-ray bursts (GRBs) offer an extraordinary opportunity to study aspects of the early Universe, including the cosmic star formation rate (SFR). Motivated by the two recent highest-z GRBs, GRB 080913 at z = 6.7 and GRB…

It has long been known that there are two classes of gamma-ray bursts (GRBs), mainly distinguished by their durations. The breakthrough in our understanding of long-duration GRBs (those lasting more than ~2 s), which ultimately linked them…

The optical afterglow of long-duration GRB 071003 is among the brightest yet to be detected from any GRB, with R ~ 12 mag in KAIT observations starting 42 s after the GRB trigger, including filtered detections during prompt emission.…

We find that the local galactic extinction towards the field of gamma-ray burst GRB970228 is $A_V=1.09^{+0.10}_{-0.20}$, which implies a substantial dimming and change in the spectral slope of the intrinsic GRB970228 afterglow. We measure a…

Understanding the reasons for the faintness of the optical/near-infrared afterglows of the so-called dark bursts is essential to assess whether they form a subclass of GRBs, and hence for the use of GRBs in cosmology. With VLT and other…

The recent evidence that the light curves and the spectra of the afterglows of GRB 970228 and GRB 980326 appear to contain a SN component, in addition to a relativistic shock wave component, provide direct clues that at least the long GRBs…

Gamma Ray Bursts (GRBs) are bright, brief flashes of high energy photons that have fascinated scientists for 30 years. They come in two classes: long (>2 s), softspectrum bursts and short, hard events. The major progress to date on…

It is clear that optical selection effects have distorted the "true" GRB redshift distribution to its presently observed biased distribution. We constrain a statistically optimal model that implies GRB host galaxy dust extinction could…

The relative brightening and reddening of the optical afterglows of GRB 970228 and GRB 980326 around 20 - 30 days after these bursts have been attributed to supernovae, which are red (blueward of their spectral peak), and which peak in time…

Long-duration Gamma-Ray Bursts (GRBs) allow us to pinpoint and study star-forming galaxies in the early universe, thanks to their orders of magnitude brighter peak luminosities compared to other astrophysical sources, and their association…

Gamma-ray bursts (GRBs) are believed to be powered by ultrarelativistic jets. If these jets encounter and accelerate excess electrons and positrons produced by particle dark matter (DM) annihilation, the observed electromagnetic radiation…

Short GRBs are commonly thought to originate from the merging of double compact object binaries but direct evidence for this scenario is still missing. Optical observations of short GRBs allow us to measure redshifts, firmly identify host…

We present an optical-to-X-ray spectral analysis of the afterglow of GRB 020405. The optical spectral energy distribution not corrected for the extragalactic extinction is significantly below the X-ray extrapolation of the single powerlaw…

Gamma-Ray Bursts (GRBs) fall into two classes: short-hard and long-soft bursts. The latter are now known to have X-ray and optical afterglows, to occur at cosmological distances in star-forming galaxies, and to be associated with the…

The afterglows of gamma-ray bursts (GRBs) have more soft X-ray absorption than expected from the foreground gas column in the Galaxy. While the redshift of the absorption can in general not be constrained from current X-ray observations, it…

GRB 970828 was the first well-localized gamma-ray burst (GRB) X-ray afterglow for which no optical afterglow was found despite a prompt, deep search down to R_lim ~ 24.5 mag. We report the discovery of a short-lived radio flare within the…

We present 5.5 and 9.0 GHz observations of a sample of seventeen GRB host galaxies at 0.5<z<1.4, using the radio continuum to explore their star formation properties in the context of the small but growing sample of galaxies with similar…

Gamma-ray bursts (GRBs) have been proposed as a tool for studying star formation in the Universe, so it is crucial to investigate whether their host galaxies and immediate environments are in any way special compared with other star-forming…