Artículo
The Prompt, High-Resolution Spectroscopic View of the "Naked-Eye" GRB080319B
D'Elia, V.; Fiore, F.; Perna, R.; Krongold, Y.; Covino, S.; Fugazza, D.; Lazzati, D.; Nicastro, F.; Antonelli, L. A.; Campana, S.; Chincarini, G.; D´Avanzo, P.; Della Valle, M.; Goldoni, P.; Guetta, D.; Guidorzi, C,; Meuers, E. J. A.; Mirabel Miquele, Igor Felix
; Molinari, E.; Norci, L.; Piranomonte, S.; Stella, L.; Stratta, G.; Tagliaferri, G.; Ward, P.
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Fecha de publicación:
03/2009
Editorial:
IOP Publishing
Revista:
Astrophysical Journal
ISSN:
0004-637X
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
GRB080319B reached fifth optical magnitude during the burst prompt emission. Thanks to the Very Large Telescope (VLT)/Ultraviolet and Visual Echelle Spectrograph (UVES) rapid response mode, we observed its afterglow just 8m:30s after the gamma-ray burst (GRB) onset when the magnitude was R ~ 12. This allowed us to obtain the best signal-to-noise (S/N), high-resolution spectrum of a GRB afterglow ever (S/N per resolution element ~50). The spectrum is rich of absorption features belonging to the main system at z = 0.937, divided in at least six components spanning a total velocity range of 100 km s<sup>-1</sup>. The VLT/UVES observations caught the absorbing gas in a highly excited state, producing the strongest Fe II fine structure lines ever observed in a GRB. A few hours later, the optical depth of these lines was reduced by a factor of 4-20, and the optical/UV flux by a factor of ~60. This proves that the excitation of the observed fine structure lines is due to "pumping" by the GRB UV photons. comparison of the observed ratio between the number of photons absorbed by the excited state and those in the Fe II ground state suggests that the six absorbers are ~2-6 kpc from the GRB site, with component I ~ 3 times closer to the GRB site than components III-VI. Component I is characterized also by the lack of Mg I absorption, unlike all other components. This may be both due to a closer distance and a lower density, suggesting a structured interstellar matter in this galaxy complex.
Palabras clave:
Gamma Rays: Bursts
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Articulos(IAFE)
Articulos de INST.DE ASTRONOMIA Y FISICA DEL ESPACIO(I)
Articulos de INST.DE ASTRONOMIA Y FISICA DEL ESPACIO(I)
Citación
D'Elia, V.; Fiore, F.; Perna, R.; Krongold, Y.; Covino, S.; et al.; The Prompt, High-Resolution Spectroscopic View of the "Naked-Eye" GRB080319B; IOP Publishing; Astrophysical Journal; 694; 1; 3-2009; 332-338
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