Long γ-ray bursts and core-collapse supernovae have different environments
Pian, E.; Ferguson, H. C.; Gull, T. R.; Garnavich, P. M.; Nugent, P. E.; Kouveliotou, C.; Fruchter, A. S.; Vreeswijk, P. M.; Wijers, R. A. M. J.; Thorsett, S. E.; Fynbo, J. P. U.; Gorosabel, J.; Castro-Tirado, A. J.; Gibbons, R. A.; Levan, A. J.; Livio, M.; Smette, A.; Bersier, D.; Tanvir, N. R.; Hjorth, J.; Holland, S. T.; Woosley, S. E.; Burud, I.; Rhoads, J. E.; Castro Cerón, J. M.; Conselice, C.; Riess, A. G.; Dahlen, T.; Sahu, K. C.; Petro, L.; Strolger, L.; Levay, Z.; Metzger, M. R.
United States, Chile, Spain, Sweden, Denmark, Italy, United Kingdom, Netherlands
Abstract
When massive stars exhaust their fuel, they collapse and often produce the extraordinarily bright explosions known as core-collapse supernovae. On occasion, this stellar collapse also powers an even more brilliant relativistic explosion known as a long-duration γ-ray burst. One would then expect that these long γ-ray bursts and core-collapse supernovae should be found in similar galactic environments. Here we show that this expectation is wrong. We find that the γ-ray bursts are far more concentrated in the very brightest regions of their host galaxies than are the core-collapse supernovae. Furthermore, the host galaxies of the long γ-ray bursts are significantly fainter and more irregular than the hosts of the core-collapse supernovae. Together these results suggest that long-duration γ-ray bursts are associated with the most extremely massive stars and may be restricted to galaxies of limited chemical evolution. Our results directly imply that long γ-ray bursts are relatively rare in galaxies such as our own Milky Way.