2007A&A...467..629D


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.11CEST03:30:27

2007A&A...467..629D - Astronomy and Astrophysics, volume 467, 629-639 (2007/5-4)

UVES/VLT high resolution spectroscopy of GRB 050730 afterglow: probing the features of the GRB environment.

D'ELIA V., FIORE F., MEURS E.J.A., CHINCARINI G., MELANDRI A., NORCI L., PELLIZZA L., 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., GIOMMI P., GOLDONI P., GUETTA D., ISRAEL G., LAZZATI D., MALESANI D., MARCONI G., MASON K., MEREGHETTI S., MIRABEL F., MOLINARI E., MORETTI A., NOUSEK J., PERRI M., PIRO L., STRATTA G., TESTA V. and VIETRI M.

Abstract (from CDS):

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. To this purpose we analyze high resolution spectroscopic observations (R=20000-45000, corresponding to 14km/s at 4200Å and 6.6km/s at 9000Å) of the optical afterglow of GRB050730, obtained with UVESLT ∼4h after the GRB trigger. 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 CII*, SiII*, OI* and FeII* fine structure absorption lines associated to the second and third component. 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 CIV and OVI, 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.

Abstract Copyright:

Journal keyword(s): gamma rays: bursts - cosmology: observations - Galaxy: abundances - galaxies: ISM - line: identification - line: profiles

Nomenclature: Text: [DFM2007] GRB 050730 abs N.NNN N=5.

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 GRB 021004 gB 00 26 54.68 +18 55 41.6           ~ 519 0
2 GRB 050730 gB 14 08 17.090 -03 46 18.90   20.32 17.68     ~ 288 0
3 GRB 060418 gB 15 45 42.600 -03 38 20.00 15.73 16.19 14.98     ~ 330 0
4 GRB 020813A gB 19 46 41.874 -19 36 04.81           ~ 288 0
5 GRB 050922C gB 21 09 33.000 -08 45 30.10 15.15 15.86 14.69     ~ 257 0
6 GRB 060607 gB 21 58 50.400 -22 29 46.70 18.49 16.67 15.09     ~ 266 0
7 GRB 050820A gB 22 29 38.110 +19 33 37.10 18.33 19.00 18.47     ~ 345 0
8 GRB 051111A gB 23 12 33.170 +18 22 28.80 19.77 20.08 19.50     ~ 189 0

    Equat.    Gal    SGal    Ecl

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