49 research outputs found
Follow-up observations from observatories based in Spain
We present a review of the follow-up observations carried out from
observatories located in Spain; Calar-Alto, Izanha and Roque de Los Muchachos.
It summarizes the observations carried out by our group for 27 GRBs occurred in
the period 1999-2000, spanning from GRB 990123 to GRB 001007.Comment: 3 pages, no figures. To appear in the proceedings of the October 2000
Rome Workshop on ``Gamma-Ray Bursts in the Afterglow Era'
Infrared and Optical Observations of GRB 030115 and its Extremely Red Host Galaxy: Implications for Dark Bursts
We present near-infrared (nIR) and optical observations of the afterglow of
GRB 030115. Discovered in an infrared search at Kitt Peak 5 hours after the
burst trigger, this afterglow is amongst the faintest observed in the R-band at
an early epoch, and exhibits very red colors, with . The
magnitude of the optical afterglow of GRB 030115 is fainter than many upper
limits for other bursts, suggesting that without early nIR observations it
would have been classified as a ``dark'' burst. Both the color and optical
magnitude of the afterglow are likely due to dust extinction and indicate that
at least some optical afterglows are very faint due to dust along the line of
sight. Multicolor {\it Hubble Space Telescope} observations were also taken of
the host galaxy and the surrounding field. Photometric redshifts imply that the
host, and a substantial number of faint galaxies in the field are at . The overdensity of galaxies is sufficiently great that GRB 030115 may
have occurred in a rich high-redshift cluster. The host galaxy shows extremely
red colors (R-K=5) and is the first GRB host to be classified as an Extremely
Red Object (ERO). Some of the galaxies surrounding the host also show very red
colors, while the majority of the cluster are much bluer, indicating ongoing
unobscured star formation. As it is thought that much of high redshift star
formation occurs in highly obscured environments it may be that GRB 030115
represent a transition object, between the relatively unobscured afterglows
seen to date and a population which are very heavily extinguished, even in the
nIR.Comment: 19 Pages. ApJ 2006, 647, 47
A very energetic supernova associated with the gamma-ray burst of 29 March 2003
Over the past five years evidence has mounted that long-duration (> 2 s)
gamma-ray bursts (GRBs)--the most brilliant of all astronomical
explosions--signal the collapse of massive stars in our Universe. This evidence
was originally based on the probable association of one unusual GRB with a
supernova, but now includes the association of GRBs with regions of massive
star formation in distant galaxies, the appearance of supernova-like 'bumps' in
the optical afterglow light curves of several bursts and lines of freshly
synthesized elements in the spectra of a few X-ray afterglows. These
observations support, but do not yet conclusively demonstrate, the idea that
long-duration GRBs are associated with the deaths of massive stars, presumably
arising from core collapse. Here we report evidence that a very energetic
supernova (a hypernova) was temporally and spatially coincident with a GRB at
redshift z = 0.1685. The timing of the supernova indicates that it exploded
within a few days of the GRB, strongly suggesting that core-collapse events can
give rise to GRBs, thereby favouring the 'collapsar' model.Comment: 19 pages, 3 figure