Fermi Gamma-ray Burst Monitor detected gamma-ray emission 0.4 sec after a binary black-hole merger event, GW150914. We show that the gamma-ray emission is caused by a relativistic outflow with Lorentz factor larger than 10. Subsequently debris outflow pushes ambient gas to form a shock, which is responsible for the afterglow synchrotron emission. We find that the fluxes of radio and optical afterglows increase from about $10^7$ sec to at least $\sim10$ yr after the burst trigger. Further follow-up observations in the radio and optical/infrared bands are encouraged. Detection of afterglows will localize the sky position of the gravitational-wave and the gamma-ray emissions and it will support the physical association between them.
R. Yamazaki, K. Asano and Y. Ohira
Wed, 17 Feb 16
Comments: 9 pages, 2 figures