Study On The Spectral Lag Of Multi-Flare GRBs

Gamma-ray bursts（referred to as GRBs）are the most violent explosion phenomenon in the universe.In recent decades,as the observation conditions have become better and better,we have obtained relatively complete Gamma-ray bursts observation data,and on the basis of these observation data,we have achieved remarkable research results.However,many essential problems of GRBs have not been solved,such as the problem of energy spectrum lag of GRBs.Not only is there a spectral lag in prompt emission,there is also a spectral lag in the X-ray afterglow flares of GRBs.Flare refers to the phenomenon of protrusions or big bulges in the afterglow of X-rays,which is likely to be caused by the reactivation of the central engine.Studying the energy spectral lag properties of multi-flare GRBs can help people understand the nature of GRBs.This paper firstly introduces the related research background of GRB in several aspects such as the observation history and basic theory of GRB.Then,a comprehensive study was conducted on the lag properties of 137 flare of 48multi-flare GRBs,and the possible origin of the flare spectral lag was most explored.Finally,we based on a special GRB with 10 flare GRB,GRB 051117A,analyzed the correlation between its energy spectral lag and flare time characteristic parameters.Our results show that:1.From the perspective of the flare,the spectral lag distribution of the flare conforms to the normal distribution,and the lag of the flare is much greater than the lag of the pulse;2.The flare lag and its duration conform to the relationship of₇（62）)∝_{（9（64）9）}.Flare has the characteristic of evolving over time,that is,as time goes by,the longer the duration of the flares,the greater the spectral lag;3.Multi-flare GRBs and multi-pulse GRBs have similar characteristics in the order of positive and negative lags.It also provides support for the possibility that flares and pulses may have the same origin;4.For the cause of the lag of the spectral of multi-flare GRBs,some GRBs can be explained by spectral evolution,such as GRB 060111A,and some existing GRBs.Theory cannot explain,such as GRB 060714;5.Pulse and flare have a very good extension relationship from the₇（62）)∝_{（9（64）9）}relationship.We think this can also prove that pulse and flare may be generated by the same physical mechanism;6.Taking GRB 051117A as an example,the relationship between the spectral lag and flare characteristic parameters between GRBs can be extended to the inside of the GRB,Moreover,the correlation between the flares characteristic parameters within GRB 051117A is highly similar to that of multiple GRBs and even the prompt emission pulses.This also supports that X-ray flares and prompt emission pulses may have the same physical origin.