The Multi-wavelength Afterglow Emission Of Double Neutron Star Mergers

Neutron star(NS)-neutron star mergers have been considered to be one of the most abundant sources of multi-messenger signal in the universe,which can generate a powerful gravitational waves(GW),as well as electromagnetic waves and neutrino signals.Such transient sources could now be captured by the ground or space de-tectors,providing important parameter constraints for studying the evolution and merger models of compact binary stars.On August 17th 2017,the gravitational wave signal from a binary neutron s-tar(BNS)merger was first detected by the LIGO/virgo detectors.About 1.74 s after the merger,its electromagnetic counterpart,a short gamma ray bursts(SGRBs)named GRB 170817A,was also found by the Fermi Gamma-ray Space Telescope,a kilonova was detected by Swope telescope after the outbreak of 10.9 h.Afterwards,a lot of telescopes have participated in this observation mission and abundant record-ed,which provided important data support for the later studies on the evolution of binary stars,the properties of projectors and the combined products.This joint observations provided direct evidence for BNS merger is one of the progenitors of SGRBs and also confirmed the theoretical prediction of the radiation named kilono-va for the first time.This significant event has initiated the era of multi-messenger astronomy".This paper focus on the radiation characteristics of multi-messenger signals from binary neutron stars merger.Besides gravitational waves,the merger of binary neu-tron stars will also produce electromagnetic waves as well as neutrino radiation.With the characteristics of strong penetration and small time delay,short gamma-ray bursts are considered to be the most likely electromagnetic counterpart.In the first chap-ter of this paper,we will outline the multi-messenger signal from binary neutron stars merger and give an introduction of the observation characteristics from short gamma-ray bursts in detail.In the second chapter,we will give an overview of GRB 170817A.The observation results show that the prompt radiation of GRB 170817A is characterized by low luminosity and a small time delay after the GW burst,and the afterglow continues to brighten for 109 days after the merger.All these phenomena suggest that its projectile may have a special structure,so we discussed it in detail in sections 1 and 2.In the last two sections,we briefly introduced the kilonova and merger remnant of this event.Since a binary neutron stars blow a strong stellar wind around it during the in-spiral stage,a wind bubble environment may be formed around it.Based on this,we discuss the formation?evolution and observational signature of afterglow in the fourth chapter.We take GRB 170817A as a reference,assuming that the jet generated form the merger has a certain structure and the observer is located in an off-axis position.The final result shows that the afterglow of short bursts will show a sharp rising when the jet hit into the bubble in in the early stage,and this significant jump that can be observed by the current telescopes.In the last chapter,we make a brief summary and prospect.