학술논문
The brightest GRB ever detected: GRB 221009A as a highly luminous event at z = 0.151
Document Type
Working Paper
Author
Malesani, D. B.; Levan, A. J.; Izzo, L.; Postigo, A. de Ugarte; Ghirlanda, G.; Heintz, K. E.; Kann, D. A.; Lamb, G. P.; Palmerio, J.; Salafia, O. S.; Salvaterra, R.; Tanvir, N. R.; Fernández, J. F. Agüí; Campana, S.; Chrimes, A. A.; D'Avanzo, P.; D'Elia, V.; Della Valle, M.; De Pasquale, M.; Fynbo, J. P. U.; Gaspari, N.; Gompertz, B. P.; Hartmann, D. H.; Hjorth, J.; Jakobsson, P.; Palazzi, E.; Pian, E.; Pugliese, G.; Ravasio, M. E.; Rossi, A.; Saccardi, A.; Schady, P.; Schneider, B.; Sollerman, J.; Starling, R. L. C.; Thöne, C. C.; van der Horst, A. J.; Vergani, S. D.; Watson, D.; Wiersema, K.; Xu, D.; Zafar, T.
Source
Subject
Language
Abstract
Context: The extreme luminosity of gamma-ray bursts (GRBs) makes them powerful beacons for studies of the distant Universe. The most luminous bursts are typically detected at moderate/high redshift, where the volume for seeing such rare events is maximized and the star-formation activity is greater than at z = 0. For distant events, not all observations are feasible, such as at TeV energies. Aims: Here we present a spectroscopic redshift measurement for the exceptional GRB 221009A, the brightest GRB observed to date with emission extending well into the TeV regime. Methods: We used the X-shooter spectrograph at the ESO Very Large Telescope (VLT) to obtain simultaneous optical to near-IR spectroscopy of the burst afterglow 0.5 days after the explosion. Results: The spectra exhibit both absorption and emission lines from material in a host galaxy at z = 0.151. Thus GRB 221009A was a relatively nearby burst with a luminosity distance of 745 Mpc. Its host galaxy properties (star-formation rate and metallicity) are consistent with those of LGRB hosts at low redshift. This redshift measurement yields information on the energy of the burst. The inferred isotropic energy release, $E_{\rm iso} > 5 \times 10^{54}$ erg, lies at the high end of the distribution, making GRB 221009A one of the nearest and also most energetic GRBs observed to date. We estimate that such a combination (nearby as well as intrinsically bright) occurs between once every few decades to once per millennium.
Comment: 9 pages, 4 figures, submitted to Astronomy & Astrophysics
Comment: 9 pages, 4 figures, submitted to Astronomy & Astrophysics