Discovery of GRB 020405 and its Late Red Bump
Abstract
We present the discovery of GRB 020405 made with the Inter-Planetary Network (IPN). With a duration of 60 s, the burst appears to be a typical long duration event. We observed the 75-square acrminute IPN error region with the Mount Stromlo Observatory's 50-inch robotic telescope and discovered a transient source which subsequently decayed and was also associated with a variable radio source. We identify this source as the afterglow of GRB 020405. Subsequent observations by other groups found varying polarized flux and established a redshift of 0.690 to the host galaxy. Motivated by the low redshift we triggered observations with WFPC2 on-board the Hubble Space Telescope (HST). Modeling the early ground-based data with a jet model, we find a clear red excess over the decaying optical lightcurves that is present between day 10 and day 141 (the last HST epoch). This `bump' has the spectral and temporal features expected of an underlying supernova (SN). In particular, the red color of the putative SN is similar to that of the SN associated with GRB 011121, at late time. Restricting the sample of GRBs to those with z<0.7, a total of five bursts, red bumps at late times are found in GRB 970228, GRB 011121, and GRB 020405. It is possible that the simplest idea, namely that all long duration GRBs have underlying SNe with a modest dispersion in their properties (especially peak luminosity), is sufficient to explain the non detections.
Cite
@article{arxiv.astro-ph/0208008,
title = {Discovery of GRB 020405 and its Late Red Bump},
author = {P. A. Price and S. R. Kulkarni and E. Berger and D. W. Fox and J. S. Bloom and S. G. Djorgovski and D. A. Frail and T. J. Galama and F. A. Harrison and P. McCarthy and D. E. Reichart and R. Sari and S. A. Yost and H. Jerjen and K. Flint and A. Phillips and B. E. Warren and T. S. Axelrod and R. A. Chevalier and J. Holtzman and R. A. Kimble and B. P. Schmidt and J. C. Wheeler and F. Frontera and E. Costa and L. Piro and K. Hurley and T. Cline and C. Guidorzi and E. Montanari and E. Mazets and S. Golenetskii and I. Mitrofanov and D. Anfimov and A. Kozyrev and M. Litvak and A. Sanin and W. Boynton and C. Fellows and K. Harshman and C. Shinohara and A. Gal-Yam and E. Ofek and Y. Lipkin},
journal= {arXiv preprint arXiv:astro-ph/0208008},
year = {2009}
}
Comments
(Fixing HST data table; thanks to N. Masetti.) 18 pages, 3 figures (2 in colour). Accepted to appear in the Astrophysical Journal