R-Mode Gravitatioanl-Wave Radiation And Its Electromagnetic Counterpart

Since the signature of gravitational wave and electromagnetic waves from a binary neutron star merge was first simultaneously detected by human being,which means that astrophysics has entered a new era.Human beings have another key to explore the universe due to its appearance makes the human not only can see the universe but also can listen to the sound of the universe.However,what is the post-merger remnant of a binary neutron star still puzzles the modern astrophysics community.In this paper,we assume that the post-merger remnant of a binary neutron star is a supermassive magnetars and carry out a series of studies on that.The research on the R-mode instability of neutron stars has made remarkable achievements in the past decades.R-mode gravitational-wave radiation has attracted extensive attention from astrophysicists since it was discovered that the gravitational wave driving the rotating neutron star’s R-mode instability by the CFS mechanism.By assuming that R-mode instability can also be operated in a magnetar.when the central engine of GRBs is a magnetar and a large fraction of the rotational energy of a magnetar is lost due to r-mocde gravitational-wave radiation,then what kind of phenomenon will we see in the light curve of GRBs.This may help us understand the physics of neutron stars and gamma-ray bursts,and determine what the products of binary mergers are?Considering that the spin evolution of magnetar is governed by both gravitational-radiation generated by unstable R-mode oscillation at early-time and magnetic dipole radiation dominating late-time spin-down evolution,theoretically,we obtained the light curve of gamma-ray burst under assuming that the magnetic inclination angle change sharply.We found that the X-ray light curves of the SGRB 090510 were consistent with those predicted by our theoretical model,which means that we have reason to believe that the post-merger remnant of a binary NSs is a super-massive magnetar and implies that R-mode gravitational waves may play an important role in the post-merger remnant.We also discussed the detectability of R-mode gravitational waves in this paper.It was found that the gravitational wave observatory aLIGO could not directly detect this type of gravitational waves until it was less than 1Mpc distance.With the results of the previous study,we also discussed the possibility that if most of the rotational energy of a magnetar was taken away by R-mode gravitational-wave radiation,the magnetar may collapse into a newborn black hole.At this time,some stellar envelop materials may fall back and accretion onto black holes and drive outflow into gamma-ray bursts and supermovae.Then,the corresponding light curves of gamma-ray bursts may exhibit a bump and accompanied by supernovae observation.We found that GRB 111209A and its associated supernovae 201 lkl can be well explained simultaneously in the theoretical framework.In addition,using the collapse time of GRB 111209A,we try to constrain the equation of state of neutron stars.In this paper,the radiation efficiency of gamma-ray bursts and the micro-physical quantities of their jets are also studied by using the data of Fermi and Swift satellites.