The afterglow and host galaxy of GRB 090205: evidence for a Ly-alpha emitter at z=4.65 - Astrophysics > High Energy Astrophysical PhenomenaReport as inadecuate




The afterglow and host galaxy of GRB 090205: evidence for a Ly-alpha emitter at z=4.65 - Astrophysics > High Energy Astrophysical Phenomena - Download this document for free, or read online. Document in PDF available to download.

Abstract: Gamma-ray bursts have been proved to be detectable up to distances muchlarger than any other astrophysical object, providing the most effective way,complementary to ordinary surveys, to study the high redshift universe. To thisend, we present here the results of an observational campaign devoted to thestudy of the high-z GRB 090205. We carried out optical-NIR spectroscopy andimaging of GRB 090205 with the ESO-VLT starting from hours after the event upto several days later to detect the host galaxy. We compared the resultsobtained from our optical-NIR observations with the available Swift high-energydata of this burst. Our observational campaign led to the detection of theoptical afterglow and host galaxy of GRB 090205 and to the first measure of itsredshift, z=4.65. Similar to other, recent high-z GRBs, GRB 090205 has a shortduration in the rest-frame with T {90,rf}=1.6 s, which suggests the possibilitythat it might belong to the short GRBs class. The X-ray afterglow of GRB 090205shows a complex and interesting behaviour with a possible rebrightening at500-1000s from the trigger time and late flaring activity. Photometricobservations of the GRB 090205 host galaxy argue in favor of a starburst galaxywith a stellar population younger than ~ 150 Myr. Moreover, the metallicity ofZ > 0.27 Z Sun derived from the GRB afterglow spectrum is among the highestderived from GRB afterglow measurement at high-z, suggesting that the burstoccurred in a rather enriched envirorment. Finally, a detailed analysis of theafterglow spectrum shows the existence of a line corresponding to Lyman-alphaemission at the redshift of the burst. GRB 090205 is thus hosted in a typicalLyman-alpha emitter LAE at z=4.65. This makes the GRB 090205 host thefarthest GRB host galaxy, spectroscopically confirmed, detected to date.



Author: P. D'Avanzo, M. Perri, D. Fugazza, R. Salvaterra, G. Chincarini, R. Margutti, X. F. Wu, C. C. Thoene, A. Fernandez-Soto, T.

Source: https://arxiv.org/







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