Implications of Possible Alternate Scenarios for Short and Long Duration GRBs

Abstract

Gamma-ray bursts (GRB) are the most luminous physical phenomena in the universe, consisting of flashes of gamma rays that last from seconds to hours. In this paper we look at possible alternate scenarios for both short and long duration GRBs. We consider scenarios for short duration GRBs,which could explainwhy fewer GRBs are observed than what is expected. Also a new class of objects (dark matter objects) is proposed as possible candidate for short duration GRBs which eliminates the baryon load problem, which could also provide a possible scenario for the formation of sub- stellar black holes, distinct from the usual Hawking black hole.We also consider a new model (dubbed the Smashnova model)where an SN can trigger a GRB.In case of long duration GRBs, we propose the possibility of a GRB triggering the collapse of a WR or RG star in a binary system producing an SN, and typical signatures. We also discuss GRBs from population III stars of ~500 �� at high redshifts,and argue that collapse of such high mass stars does not lead to GRBs. Observational implications for the above scenarios are briefly explained.