Friday, December 3, 2010, Noon, Phillips Auditorium
Exotic Dust and Obscured Star Formation in the Distant Universe
Unveiled by Gamma-Ray Bursts
Daniel Perley (UC Berkeley)
| The ultimate cosmic lighthouses, GRBs and their afterglows can be observed out to the most distant parts of the observable universe. Canonically, they are believed to occur nearly exclusively in low-mass, high-sSFR galaxies and are nearly unaffected by dust extinction, usually showing an extinction curve reminiscent of nearby dwarf galaxies or the SMC. In my talk, I will discuss three important revisions to this picture: (1) Evidence that a large fraction of GRBs are actually heavily obscured by dust in their host, while few are at high redshifts of z>5; (2) Measurements of a wide diversity of extinction curves, including Milky Way-like dust at z=3 as well as examples of extinction curves with no local analog; (3) Evidence that the most dust-obscured bursts may originate in massive, dusty, and metal-rich galaxies, potentially revitalizing the use of GRBs as cosmic SFR probes and calling into question models which require an exclusively low-metallicity progenitor. |
