Late-time Observations of GRB 080319B: Jet Break, Host Galaxy, and Accompanying Supernova
Abstract
The Swift-discovered GRB 080319B was by far the most distant source ever observed at naked-eye brightness, reaching a peak apparent magnitude of 5.3 at a redshift of z = 0.937. We present our late-time optical (Hubble Space Telescope, Gemini, and Very Large Telescope) and X-ray (Chandra) observations, which confirm that an achromatic break occurred in the power-law afterglow light curve at ~11 days post-burst. This most likely indicates that the gamma-ray burst (GRB) outflow was collimated, which for a uniform jet would imply a total energy in the jet E jet >~ 1052 erg. Our observations also show a late-time excess of red light, which is well explained if the GRB was accompanied by a supernova (SN), similar to those seen in some other long-duration GRBs. The latest observations are dominated by light from the host and show that the GRB took place in a faint dwarf galaxy (r(AB) ≈ 27.0, rest frame MB ≈ -17.2). This galaxy is small even by the standards of other GRB hosts, which is suggestive of a low-metallicity environment. Intriguingly, the properties of this extreme event—a small host and bright SN—are entirely typical of the very low luminosity bursts such as GRB 980425 and GRB 060218.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2010
- DOI:
- 10.1088/0004-637X/725/1/625
- arXiv:
- arXiv:0812.1217
- Bibcode:
- 2010ApJ...725..625T
- Keywords:
-
- galaxies: high-redshift;
- gamma-ray burst: individual: GRB 080319B;
- supernovae: individual;
- Astrophysics
- E-Print:
- Revised in response to referee's comments, and with some additional data added