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arXiv · 0803.2235

On the distribution of stellar masses in gamma-ray burst host galaxies

J. M. Castro Cerón·M. J. Michałowski·J. Hjorth·D. Malesani·J. Gorosabel·D. Watson·J. P. U. Fynbo·M. Morales Calderón·;
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Abstract

We analyse Spitzer images of 30 long-duration gamma-ray burst (GRB) host galaxies. We estimate their total stellar masses (M*) based on the rest-frame K-band luminosities (L_Krest) and constrain their star formation rates (SFRs, not corrected for dust extinction) based on the rest-frame UV continua. Further, we compute a mean M*/L_Krest = 0.45 Msun/Lsun. We find that the hosts are low M*, star-forming systems. The median M* in our sample ( = 10^9.7 Msun) is lower than that of "field" galaxies (e.g., Gemini Deep Deep Survey). The range spanned by M* is 10^7 Msun < M* < 10^11 Msun, while the range spanned by the dust-uncorrected UV SFR is 10^-2 Msun yr^-1 < SFR < 10 Msun yr^-1. There is no evidence for intrinsic evolution in the distribution of M* with redshift. We show that extinction by dust must be present in at least 25% of the GRB hosts in our sample and suggest that this is a way to reconcile our finding of a relatively lower UV-based, specific SFR (PHI = SFR/M*) with previous claims that GRBs have some of the highest PHI values. We also examine the effect that the inability to resolve the star-forming regions in the hosts has on PHI.

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J. M. Castro Cerón, M. J. Michałowski, J. Hjorth, D. Malesani, J. Gorosabel, D. Watson, J. P. U. Fynbo, M. Morales Calderón, ;. 2008-03-17. On the distribution of stellar masses in gamma-ray burst host galaxies. https://doi.org/10.1088/0004-637x/721/2/1919

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