Brad Cenko
UC Berkeley
ABSTRACT
I review two recent articles in the field of explosive transients: "A glimpse of the end of the dark ages: the gamma-ray burst of 23 April 2009 at redshift 8.3" (Tanvir et al., astro-ph/0906.1577) and "A new type of stellar explosion" (Perets et al., astro-ph/0906.2003). With their bright though short-lived afterglows, gamma-ray bursts are now routinely used as cosmological tools - both as signposts tracing the star formation history of the universe, and as beacons illuminating intervening material along the line of sight. With the discovery of the z = 8.3 GRB090423, the most distant spectroscopically confirmed object in the universe, GRBs now offer the promise of constraining the epoch of reionization, and I discuss future prospects for such work. SN2005E, on the other hand, was a relatively nearby supernovae who spectra indicate an origin from the core-collapse of a massive star that had lost its H envelope (Type Ib). However, this picture is inconsistent with the environment of SN2005E, which exploded far away from the disk of its host galaxy in a region completely devoid of recent star formation. I outline possible theoretical explanations for this puzzle, and highlight the burgeoning field of "unusual" supernovae and upcoming experiments that will likely identify many more such objects.