A black hole-white dwarf compact binary model for long gamma-ray bursts without supernova association

Abstract

Gamma-ray bursts (GRBs) are luminous and violent phenomena in theUniverse. Traditionally, long GRBs are expected to be produced by the collapse ofmassive stars and associated with supernovae. However, some low-redshift long GRBs have no detection of supernova association, such as GRBs 060505, 060614, and 111005A. It is hard to classify these events convincingly according to usual classifications, and the lack of the supernova implies a non-massive star origin. We propose a new path to produce long GRBs without supernova association, the unstable and extremely violent accretion in a contact binary system consisting of a stellar-mass black hole and a white dwarf, which fills an important gap in compact binary evolution.