Authors: Piranomonte, S.; Ward, P. A.; Fiore, F.; Vergani, S. D.; D'Elia, V.; Krongold, Y.; Nicastro, F.; Meurs, E. J. A.; Chincarini, G.; Covino, S.; Della Valle, M.; Fugazza, D.; Norci, L.; Sbordone, L.; Stella, L.; Tagliaferri, G.; Burrows, D. N.; Gehrels, N.; Goldoni, P.; Malesani, D.; Mirabel Miquele, Igor Felix; Pellizza González, Leonardo Javier; Perna, R.
Publication Date: 2008.
Language: English.
Abstract:
Aims. The aim of this paper is to investigate the environment of gamma ray bursts (GRBs) and the interstellar matter of their host galaxies. Methods. To this purpose we use high resolution spectroscopic observations of the afterglow of RB050922C, obtained with UVES/VLT ∼ 3.5 h after the GRB event. Results. We found that, as for most high resolution spectra of GRBs, the spectrum of the afterglow of GRB050922C is complex. At least seven components contribute to the main absorption system at z = 2.1992. The detection of lines of neutral elements like MgI and the detection of fine-structure levels of the ions FeII, SiII and CII allows us to separate components in the GRB ISM along the line of sight. Moreover, in addition to the main system, we analyzed the five intervening systems between z = 2.077 and z = 1.5664 identified along the GRB line of sight. Conclusions. GRB afterglow spectra are very complex, but full of information. This can be used to disentangle the contribution of the different parts of the GRB host galaxy and to study their properties. Our metallicity estimates agree with the scenario of GRBs exploding in low metallicity galaxies
Author affiliation: Piranomonte, S.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Ward, P. A.. Mullard Space Science Laboratory; Reino Unido
Author affiliation: Fiore, F.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Vergani, S. D.. Dublin Institute for Advanced Studies; Irlanda
Author affiliation: D'Elia, V.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Krongold, Y.. Universidad Nacional Autónoma de México; México
Author affiliation: Nicastro, F.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Meurs, E. J. A.. Dublin City University; Irlanda
Author affiliation: Chincarini, G.. Osservatorio Astronomico di Brera; Italia
Author affiliation: Covino, S.. Osservatorio Astronomico di Brera; Italia
Author affiliation: Della Valle, M.. Osservatorio Astronomico di Capodimonte; Italia
Author affiliation: Fugazza, D.. Osservatorio Astronomico di Brera; Italia
Author affiliation: Norci, L.. Dublin Institute for Advanced Studies; Irlanda
Author affiliation: Sbordone, L.. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia
Author affiliation: Stella, L.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Tagliaferri, G.. Osservatorio Astronomico di Brera; Italia
Author affiliation: Burrows, D. N.. University of Pennsylvania; Estados Unidos
Author affiliation: Gehrels, N.. National Aeronautics And Space Administration; Estados Unidos
Author affiliation: Goldoni, P.. Laboratoire Astroparticule et Cosmologie; Francia
Author affiliation: Malesani, D.. Niels Bohr Institute; Dinamarca
Author affiliation: Mirabel Miquele, Igor Felix. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Author affiliation: Pellizza González, Leonardo Javier. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Author affiliation: Perna, R.. State University Of Colorado Boulder; Estados Unidos
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: D'Elia, V.; Fiore, F.; Meurs, E. J. A.; Chincarini, G.; Melandri, A.; Norci, L.; Pellizza González, Leonardo Javier; Perna, R.; Piranomonte, S.; Sbordone, L.; Stella, L.; Tagliaferri, G.; Vergani, S. D.; Ward, P.; Angelini, L.; Antonelli, L. A.; Burrows, D. N.; Campana, S.; Capalbi, M.; Cimatti, A.; Costa, E.; Cusumano, G.; Della Valle, M.; Filliatre, P.; Fontana, A.; Frontera, F.; Fugazza, D.; Gehrels, N.; Giannini, T.; Mirabel Miquele, Igor Felix
Publication Date: 2007.
Language: English.
Abstract:
Aims. The aim of this paper is to study the Gamma Ray Burst (GRB) environment through the analysis of the optical absorption features due to the gas surrounding the GRB. Methods. To this purpose we analyze high resolution spectroscopic observations (R = 20 000–45 000, corresponding to 14 km s−1 at 4200 Å and 6.6 km s−1 at 9000 Å) of the optical afterglow of GRB050730, obtained with UVES@VLT ∼4 h after the GRB trigger. Results. The spectrum shows that the ISM of the GRB host galaxy at z = 3.967 is complex, with at least five components contributing to the main absorption system. We detect strong C II*, Si II*, O I* and Fe II* fine structure absorption lines associated to the second and third component. Conclusions. For the first three components we derive information on the relative distance from the site of the GRB explosion. Component 1, which has the longest wavelength, highest positive velocity shift, does not present any fine structure nor low ionization lines; it only shows very high ionization features, such as C IV and O VI, suggesting that this component is very close to the GRB site. From the analysis of low and high ionization lines and fine structure lines, we find evidences that the distance of component 2 from the site of the GRB explosion is 10–100 times smaller than that of component 3. We evaluated the mean metallicity of the z = 3.967 system obtaining values ≈10−2 of the solar metallicity or less. However, this should not be taken as representative of the circumburst medium, since the main contribution to the hydrogen column density comes from the outer regions of the galaxy while that of the other elements presumably comes from the ISM closer to the GRB site. Furthermore, difficulties in evaluating dust depletion correction can modify significantly these values. The mean [C/Fe] ratio agrees well with that expected by single star-formation event models. Interestingly the [C/Fe] of component 2 is smaller than that of component 3, in agreement with GRB dust destruction scenarios, if component 2 is closer than component 3 to the GRB site.
Author affiliation: D'Elia, V.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Fiore, F.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Meurs, E. J. A.. Dunsink Observatory; Irlanda
Author affiliation: Chincarini, G.. Osservatorio Astronomico di Brera,; Italia
Author affiliation: Melandri, A.. Liverpool John Moores University; Reino Unido
Author affiliation: Norci, L.. Dublin City University; Irlanda
Author affiliation: Pellizza González, Leonardo Javier. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Author affiliation: Perna, R.. State University Of Colorado Boulder; Estados Unidos
Author affiliation: Piranomonte, S.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Sbordone, L.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Stella, L.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Tagliaferri, G.. Osservatorio Astronomico di Brera; Italia
Author affiliation: Vergani, S. D.. Dublin City University; Irlanda
Author affiliation: Ward, P.. Dunsink Observatory; Irlanda
Author affiliation: Angelini, L.. National Aeronautics And Space Administration. Goddart Institute For Space Studies; Estados Unidos
Author affiliation: Antonelli, L. A.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Burrows, D. N.. State University Of Pennsylvania; Estados Unidos
Author affiliation: Campana, S.. Osservatorio Astronomico di Brera; Italia
Author affiliation: Capalbi, M.. Science Data Center; Italia
Author affiliation: Cimatti, A.. Osservatorio Astronomico di Arcetri,; Italia
Author affiliation: Costa, E.. INAF; Italia
Author affiliation: Cusumano, G.. Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo; Italia
Author affiliation: Della Valle, M.. Osservatorio Astronomico di Arcetri; Italia
Author affiliation: Filliatre, P.. Centre D; Francia
Author affiliation: Fontana, A.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Frontera, F.. Universita; Italia
Author affiliation: Fugazza, D.. Osservatorio Astronomico di Brera,; Italia
Author affiliation: Gehrels, N.. National Aeronautics And Space Administration. Goddart Institute For Space Studies; Estados Unidos
Author affiliation: Giannini, T.. Osservatorio Astronomico di Roma; Italia
Author affiliation: Mirabel Miquele, Igor Felix. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas