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Short-hard GRB: II. afterglows
The afterglows of short-hard GRBs (SHBs) can help probe their environments, as well as the properties of the central source that produces SHBs. Afterglow observations can constrain the external density, and help distinguish between densities typical of the interstellar medium inside the host galaxy, intra-cluster medium in a cluster environment, or intergalactic medium (as might be expected if the SHB progenitor had a natal kick and a relatively long lifetime from formation to GRB production). Some flaring features might suggest late time activity of the central source, which if true, imply rather strong requirements on the central source. The observation or lack of a jet break constrain the collimation of the relativistic outflow, which relates to the launching of the jet and the true SHB event rate. Detection or lack thereof, of early optical transient emission can constrain binary merger models, where such a mini-supernova (or macronova) emission might be expected, powered by radioactive decay in Newtonian ejecta that is thrown out during the merger. Comparison of the prompt and afterglow emission constrain the efficiency of the gamma-ray emission. All these issues, and perhaps also a few others, will be discussed in this meeting.
- Recommended Reading:
- (Nakar 2006 only section 4): a great new review on short-hard GRBs (SHBs), and hte relevant section covers most of the topics to be discussed in this meeting.
- (Bloom et al. 2006 only section 6) and (Lee et al. 2005 only section 3): discuss the first afterglow of a SHB (050509B), and what can be learned from it.
- (Hjorth et al. 2005a): constrains the optical emission from 1.85 days to 23 days after GRB 050509B (the first SHB with an afterglow), and constrains mini-supernova type emission that might be expected in binary mergers.
- (Panaitescu 2006): models in detail the afterglows of SHBs 050709 and 050724.
- Additional Reading (not required):
- (Fox et al. 2005):
reports detailed observations of SHB 050709, and in particular finds ~3\sigma evidence for a late (16 days) large amplitude (\Delta F / F ~ 10) X-ray flare (\Delta t / t ~ 0.005).
- (Hjorth et al. 2005b): reports the first detection of an optivcal afterglow from a SHB (050709).
- (Berger et al. 2005): models the afterglow emission of SHB 050724.
- (Campana et al. 2006): studies the X-ray afterglow of SHB 050724.
- (Grupe et al. 2006): reports evidence for lack of a jet break in the afterglow of SHB 050724.
- (Burrows et al. 2006): reports evidence for a jet break in the afterglow of SHB 051221a.
- (Soderberg et al. 2006): observations and detailed afterglow modeling of SHB 051221a.
- (Li & Paczynski 1998): works out a simple analytic model for the transient optical emission expected from a binary merger (the 'mini-suprenova' model).
- (Kulkarni 2005): works out in more detail the expected observastional signatures from a radioactively powered transient optical emission following a binary merger (which he names 'macronova' instead of 'mini-suprnova').
MASS: Kyle Watters