Spatially resolved properties of the GRB 060505 host: implications for the nature of the progenitor

C. Thone, J. Fynbo, G. Ostlin, B. Milvang-Jensen, K. Wiersema, D. Malesani, Desiree Della Monica Ferreira, J. Gorosabel, D. Kann, D. Watson, M. Michalowski, A. Fruchter, A. Levan, J. Hjorth, J. Sollerman

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GRB 060505 was the first well-observed nearby possible long-duration gamma-ray burst (GRB) that had no associated supernova. Here we present spatially resolved spectra of the host galaxy of GRB 060505, an Sbc spiral, at redshift z = 0.0889. The GRB occurred inside a star-forming region in the northern spiral arm at 6.5 kpc from the center. From the position of the emission lines, we determine a maximum rotational velocity for the galaxy of v ~ 212 km s-1, corresponding to a mass of 1.14 × 1011 M⊙ within 11 kpc from the center. By fitting single-age spectral synthesis models to the stellar continuum, we derive a very young age for the GRB site, confirmed by photometric and Ha line measurements, of around ~6 Myr, which corresponds to the lifetime of a 32 M⊙ star. The metallicity derived from several emission-line measurements varies throughout the galaxy and is lowest at the GRB site. Using the two degree field galaxy redshift survey we can locate the host galaxy in its large-scale (~Mpc) environment. The galaxy lies in the foreground of a filamentary overdensity, extending southwest from the galaxy cluster Abell 3837 at z = 0.0896. The properties of the GRB site are similar to those found for other long-duration GRB host galaxies with high specific star formation rate and low metallicity, which is an indication that GRB 060505 originated from a young, massive star that died without making a supernova.
Original languageEnglish
JournalAstrophysical Journal
Issue number2
Pages (from-to)1151-1161
Publication statusPublished - 2008
Externally publishedYes

Cite this

Thone, C., Fynbo, J., Ostlin, G., Milvang-Jensen, B., Wiersema, K., Malesani, D., Ferreira, D. D. M., Gorosabel, J., Kann, D., Watson, D., Michalowski, M., Fruchter, A., Levan, A., Hjorth, J., & Sollerman, J. (2008). Spatially resolved properties of the GRB 060505 host: implications for the nature of the progenitor. Astrophysical Journal, 676(2), 1151-1161.