* Astronomy

Blobrana · L

RE: GRB 100621A

Blobrana · L

Title: The unusual afterglow of the Gamma-Ray Burst 100621A
Authors: J. Greiner, T. Krühler, M. Nardini, R. Filgas, A. Moin, C. de Breuck, F. Montenegro-Montes, A. Lundgren, S. Klose, P.M.J. Afonso, F. Bertoldi, J. Elliott, D.A. Kann, F. Knust, K. Menten, A. Nicuesa Guelbenzu, F. Olivares E., A. Rau, A. Rossi, P. Schady, S. Schmidl, G. Siringo, L. Spezzi, V. Sudilovsky, S.J. Tingay, A.C. Updike, Z. Wang, A. Weiss, M. Wieringa, F. Wyrowski

In order to constrain the broad-band spectral energy distribution of the afterglow of GRB 100621A, dedicated observations were performed in the optical/near-infrared with the 7-channel "Gamma-Ray Burst Optical and Near-infrared Detector" (GROND) at the 2.2m MPG/ESO telescope, in the sub-millimetre band with the large bolometer array LABOCA at APEX, and at radio frequencies with ATCA. Utilising also Swift X-ray observations, we attempt an interpretation of the observational data within the fireball scenario.
The afterglow of GRB 100621A shows a very complex temporal as well as spectral evolution. We identify three different emission components, the most spectacular one causing a sudden intensity jump about one hour after the prompt emission. The spectrum of this component is much steeper than the canonical afterglow. We interpret this component using the prescription of Vlasis et al. (2011) for a two-shell collision after the first shell has been decelerated by the circumburst medium. We use the fireball scenario to derive constraints on the microphysical parameters of the first shell. Long-term energy injection into a narrow jet seems to provide an adequate description. Another noteworthy result is the large (A_V = 3.6 mag) line-of-sight host extinction of the afterglow in an otherwise extremely blue host galaxy.

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Blobrana · L

Record-breaking X-ray blast briefly blinds space observatory

A blast of the brightest X-rays ever detected from beyond our Milky Way galaxy's neighbourhood temporarily blinded the X-ray eye on NASA's Swift space observatory earlier this summer, astronomers now report. The X-rays travelled through space for 5-billion years before slamming into and overwhelming Swift's X-ray Telescope on June 21. The blindingly bright blast came from a gamma-ray burst, a violent eruption of energy from the explosion of a massive star morphing into a new black hole.

"This gamma-ray burst is by far the brightest light source ever seen in X-ray wavelengths at cosmological distances" - David Burrows, senior scientist and professor of astronomy and astrophysics at Penn State University and the lead scientist for Swift's X-ray Telescope (XRT).

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