The Study Of Pulsar Search And Velocity Using Gaia DR2

The study of pulsars has important implications for the development of astrophysics.There are estimated to be more than 108 pulsars in the Milky Way,so it is important to search for more and exotic pulsars,and the study of pulsar velocities plays an important role in understanding their formation and evolution.Therefore,this paper mainly consists of two parts:one is to search for pulsars in binary system;The second is the study of pulsar velocities.Pulsars in compact binary systems are unique laboratories to probe gravitational theories,measure pulsar masses and study the formation and evolution of binary systems.However,such binary systems are difficult to find because of their orbital modulation and eclipse of companions.New surveys at both radio and optical wavelengths open up new opportunities to search for pulsars in compact binaries with novel methods.In this work,we combined radio continuum surveys with the Gaia DR2 catalogue,and based on their radio-optical association,setting conditions of precisely parallax and proper motion measurements,using properties of large transverse velocity and steep spectral index of pulsar.Meanwhile,we examined the radio images and optical types of the radio-optical counterpart using RACS's high sensitivity Radio Sky Survey and Aladin software.Finally,we identified a sample of 8 pulsar candidates.Thanks to the high sensitivity of FAST,we will be able to detect their periodic signals with short integration and therefore avoid the effect of potential strong orbital modulation.We propose to search for their periodic singles with FAST.We apply for a new method to select pulsar candidates,and suppose to find a new pulsar using radio telescope to identify the feasibility of the way.Precise measurements of neutron star(NS)velocities provide critical clues for the understanding of supernova physics and evolution of binary systems.Based on Gaia Data Release 2(DR2),we selected a sample of 24 young(<3Myr)pulsars,including two binary systems(PSRs B1259-63 and J2032+4127),with precise parallax and proper motion measurements and measured the velocity of their local standard of rest(LSR)and the velocity dispersion among their respective local stellar groups.The median velocity difference between thus calculated LSRs and the Galactic rotation model is 7.6 km/s,small compared to the typical velocity dispersion of 27.5 km/s.For pulsars off the Galactic plane,such difference grow significantly to as large as 40 km/s.More importantly,the velocity dispersion of stars in the local group of low-velocity pulsars can be comparable to their transverse velocities,suggesting that the intrinsic velocities of NS progenitors should be taken into account when we consider their natal kicks and binary evolution.We also examined the double NS systems J0737-3039A/B,and measured its transverse velocity to be 26-13+18 km/s assuming nearby Gaia sources being representative of its birth environment.This work demonstrated the feasibility and importance of using Gaia data to study the velocity of individual systems and velocity distribution of NSs.