The Effect Of A Magnetar Engine On The Gamma-ray Burst-associated Supernovae

Gamma-ray bursts（GRBs）,one of the most energetic phenomena in the uni-verse,appear as the sudden increase and rapid decrease of the gamma-ray flux in one direction of the sky.They were first detected by the U.S.Vela satellites in 1967.In recent decades,with the discovery of the multi-band afterglow of gamma-ray bursts and the launch of satellites like Swift and Fermi,these events have been more de-tailed studied.However,until now there is no definitive answer to the origin of these explosions.It is widely thought that such kind of events would have a central engine,perhaps a black hole,or a neutron star with a strong magnetic field（a magnetar）.The presence of the plateau and X-ray flare signals in the afterglow of the gamma-ray bursts provides evidence for the existence of a magnetar central engine.Those gamma-ray bursts with long time scales are thought to be from the collapse of massive stars.There would be another type of violent explosion known as core-collapse super-novae happening in these events.These supernovae,which are associated with long gamma-ray bursts,are called gamma-ray burst-associated supernovae（GRB-SNe）.Compared with normal core collapsed supernovae,they typically have more kinetic energy and statistically higher luminosity.Studying these GRB-SNe will provide a new perspective on how these events exploded.In this thesis,we establish a magnetar-driven shock breakout model and study the effect of a magnetar central engine on gamma-ray burst-associated supernova ra-diation using the multiband observation data of SN 2006aj/GRB 060218.Specifically,the light curve of SN 2006aj has a significant UV-optical double-peaked feature.By fitting this double-peaked light curve,we find that the first peak of this event can be well explained by the magnetar-wind-driven shock breakout emission,and the main peak of the supernova is also partially powered by the energy injection of the magne-tar.We constrain the magnetic field strength of the magnetar to～10¹⁵G,which is consistent with the result inferred from the afterglow of those long gamma-ray bursts.In addition,we suggest that considering some special assumptions,the UV excess in the late time light curve of the supernova may be from the no-thermal radiation of the pulsar wind nebula.Our study suggests that the energy injection from the central engine magnetar can explain the special properties of GRB-SNe and further confirm the possible connection between these events and superluminous supernovae.The results of this study provide some clues to understanding the physical process of the explosion of gamma-ray bursts and their associated supernovae.