Related papers: Cosmological evolution of the absorption of $\gamm…
The association of long gamma-ray bursts (GRBs) with Type Ib/c supernovae implies that they explode into the winds of their Wolf-Rayet progenitor stars. Although the evolution of some GRB afterglows is consistent with expansion into a free…
The study of the properties of galaxies in the first billion years after the Big Bang is one of the major topic of current astrophysics. Optical/near-infrared spectroscopy of the afterglows of long Gamma-ray bursts (GRBs) provide a powerful…
We present optical and near-infrared searches for afterglow emission from the first four Swift bursts with accurate positions from the X-ray Telescope (XRT). Using telescopes at Las Campanas, Keck, and Palomar observatories we rapidly…
We predict the rate at which Gamma-Ray Burst (GRB) afterglows should be detected in supernova searches as a function of limiting flux. Although GRB afterglows are rarer than supernovae, they are detectable at greater distances because of…
We present the results of the analysis of gamma-ray and X-ray data of GRB 050401 taken with the Swift satellite, together with a series of ground-based follow-up observations. The Swift X-ray light curve shows a clear break at about 4900…
A significant fraction of gamma-ray bursts (GRBs) exhibit a plateau in the early X-ray afterglow light curve, whose mechanism remains uncertain. While the post-plateau normal decay index ($\alpha_2$) is commonly used to constrain the…
The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the favored beacons for sampling the high redshift Universe. To employ GRBs to study the cosmic terrain -- e.g., star and galaxy formation history -- GRB luminosities…
Considering the contribution of the emission from the host galaxies of gamma-ray bursts (GRBs) to the radio afterglows, we investigate the effect of host galaxies on observations statistically. For the three types of events, e.g.…
Aim of this work is a broad-band study with INTEGRAL, Swift and XMM-Newton satellites of a sample of 9 blazars (7 FSRQ and 2 BL Lac) with redshift up to about 4. The spectral analysis has shown clear evidence of a flattening of the…
We present a detailed broadband afterglow study of GRB 220101A ($10^4\lesssim\Delta T\lesssim10^7$ s) combining multi-wavelength data from soft X-rays until 6 GHz. The afterglow light curves in both X-ray and optical show distinct…
Gamma-ray Bursts (GRBs) generate powerful relativistic jets that inject a large amount of energy into their surrounding environment, producing blast waves that accelerate particles to high energies. The GRB afterglow radiation provides a…
Recent observations of the environments of gamma-ray bursts (GRBs) favour massive stars as their progenitors, which are likely to be surrounded by gas and dust. The visibility of the optical and UV emission of a GRB are expected to depend…
The bright GRB 050408 was localized by HETE-II near local midnight, enabling an impressive ground-based followup effort as well as space-based followup from Swift. The Swift data from the X-Ray Telescope (XRT) and our own optical photometry…
We use a new approach to obtain limits on the absorbing columns towards an initial sample of 10 long Gamma-Ray Bursts observed with BeppoSAX and selected on the basis of their good optical and nIR coverage, from simultaneous fits to nIR,…
We present a catalog of XMM-Newton and Chandra observations of gamma-ray burst (GRB) afterglows, reduced in a common way using the most up-to-date calibration files and software. We focus on the continuum properties of the afterglows. We…
One of the most surprising gamma-ray burst (GRB) features discovered with the Swift-X ray telescope (XRT) is a plateau phase in the early X-ray afterglow light curves. These plateaus are observed in the majority of long GRBs, while their…
Because of their brightness, gamma-ray burst (GRB) afterglows are viable targets for investigating the dust content in their host galaxies. Simple intrinsic spectral shapes of GRB afterglows allow us to derive the dust extinction. Recently,…
The afterglow of a cosmological Gamma-Ray Burst (GRB) should appear on the sky as a narrow emission ring of radius 3x10^{16}cm(t/day)^{5/8} which expands faster than light. After a day, the ring radius is comparable to the Einstein radius…
Theory suggests that about 10% of Swift-detected gamma-ray bursts (GRBs) will originate at redshifts greater than 5 yet a number of high redshift candidates may be left unconfirmed due to the lack of measured redshifts. Here we introduce…
Long gamma-ray bursts (GRBs) are commonly accepted to originate in the explosion of particularly massive stars, which gives rise to a highly relativistic jet. Internal inhomogeneities in the expanding flow give rise to internal shock waves…