Late time observations of GRB080319B

1. Late time observations of GRB080319B Nial Tanvir University of Leicester collaboration with Evert Rol, Andrew Levan, Andy Fruchter, Yoni Granot, Karl Svensson and others

2. GRB 080319B Pi of Sky Reached visual magnitude 5.3!

3. GRB 080319B Redshift = 0.94 Amazing!

4. REM & Tortora GRB 080319B Racusin et al. 2008 Bloom et al. 2009

5. Was GRB 080319B exceptional in other ways? Total energy (beaming corrected)? Accompanying supernova? Host galaxy?  Late time observations up to ~1 year post-burst.

6. HST/WFPC2 observations T+19 days T+107 days T+54 days

8. Light curve (host subtracted photometry)

9. Simple model: • 1 =1.3, 2=2.35 =0.5 Sharp achromatic break at tb=11 days Light curve (host subtracted photometry)

10. Redder bands show late time excess.

11. Redder bands show late time excess. Consistent with an additional supernova component reaching about 80% of the luminosity of SN 98bw (possibly slightly shorter duration). i.e. similar to the properties of other GRB supernovae inferred from light curve “humps”.

12. GRB 080319B Bright accompanying supernova and small host galaxy entirely typical of the very faintest GRBs!

13. Sharp, achromatic light-curve break at tb=11 days. If interpreted as a jet break, the implications for beaming corrected total energy depend on model, but most likely Etot <1052.5 erg. • Accompanying supernova with magnitude similar to SN 98bw (best fit with a template somewhat fainter and redder). • Dwarf host galaxy, which is at the faint end of the distribution of GRB hosts at comparable redshifts, and hence probably of lower metallicity. Findings:  Tanvir et al. ApJ submitted (arXiv:0812.1217)