Optical Synchrotron Precursors of Radio Hypernovae
Abstract
We examine the bright radio synchrotron counterparts of low-luminosity gamma-ray bursts and relativistic supernovae (SNe) and find that they can be powered by spherical hypernova (HN) explosions. Our results imply that radio-bright HNe are driven by relativistic jets that are choked deep inside the progenitor stars or quasi-spherical magnetized winds from fast-rotating magnetars. We also consider the optical synchrotron counterparts of radio-bright HNe and show that they can be observed as precursors several days before the SN peak with an r-band absolute magnitude of {{M}r}∼ -14 mag. While previous studies suggested that additional trans-relativistic components are required to power the bright radio emission, we find that they overestimated the energy budget of the trans-relativistic component by overlooking some factors related to the minimum energy of non-thermal electrons. If an additional trans-relativistic component exists, then a much brighter optical precursor with {{M}r}∼ -20 mag can be expected. Thus, the scenarios of radio-bright HNe can be distinguished by using optical precursors, which can be detectable from ≲ 100 Mpc by current SN surveys like the Kiso SN Survey, Palomar Transient Factory, and Panoramic Survey Telescope & Rapid Response System.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2015
- DOI:
- arXiv:
- arXiv:1411.1603
- Bibcode:
- 2015ApJ...805..164N
- Keywords:
-
- gamma rays: general;
- supernovae: general;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 7 pages, 3 figures, Published version in ApJ
