The nature of Long-GRB host galaxies from chemical abundances - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate

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Abstract: Gamma-ray bursts GRBs are the most energetic events after the Big Bang andthey have been observed up to very high redshift. By means of measures ofchemical abundances now available for the galaxies hosting such events,thoughtto originate from the explosion of very powerful supernovae Type Ib-c, wehave the opportunity to study the nature of these host galaxies. The aim ofthis paper is to identify the hosts of Long GRBs LGRBs observed both at lowand high redshift to see whether the hosts can be galaxies of the same typeobserved at different cosmic epochs. We adopt detailed chemical evolutionmodels for galaxies of different morphological type ellipticals, spirals,irregulars which follow the time evolution of the abundances of severalchemical elements H, He, $\alpha$-elements, Fe, and compare the results withthe observed abundances and abundance ratios in galaxies hosting LGRBs. We findthat the abundances and abundance ratios predicted by models devised fortypical irregular galaxies can well fit the abundances in the hosts both athigh and low redshift. We also find that the predicted Type Ib-c supernova ratefor irregulars is in good agreement with observations. Models for spirals andparticularly ellipticals do not fit the high-redshift hosts of LGRBs DLAsystems nor the low redshift hosts: in particular, ellipticals cannot possiblybe the hosts of gamma-ray-bursts at low redshift since they do not show anystar formation, and therefore no supernovae Ib-c. We conclude that the observedabundance and abundance ratios in LGRBs hosts suggest that these hosts areirregular galaxies both at high and low redshift thus showing that the hostgalaxies belong to in an evolutionary sequence.

Author: X.L. Fan, J. Yin, F. Matteucci


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