FAST Multi-beam Pulsar Drift-scan Survey Simulation And Neutron Star Masses Distribution Study

In September 2016,FAST the world largest 500 meters single-aperture Spherical surface radio telescope?FAST?in Pingtang Guizhou Province was formally built and start using,marking the early stage of fast's scientific commissioning.FAST has many important scientific objectives in the range of its working frequency,such as planetary and adjacent space events,and so on.Pulsar search is one of the main scientific targets of FAST.Its high sensitivity has great potential in finding singular pulsars and adding new pulsar samples.According to the simulates the FAST pulsar survey and optimizes the survey scheme.It has important practical value for the upcoming fast pulsar survey project.Based on the 1364 normal pulsars and 43 millisecond pulsars discovered by the Parkes mid-latitude survey?Parkes high latitude survey and Parkes multi-beam survey.The spatial distribution samples of normal pulsars and millisecond pulsars in the galaxy way are simulated by using the simulation software package PsrPopPy developed by Bates et al.Based on the parameters of FAST equipment,the simulated samples are observed in virtual way.We ensure the FAST survey simulation use center frequency is1250 MHz and the bandwidth is 400 MHz,in 19 beam receiver drift scanning mode,the whole day observation of FAST is simulated,and the integral time is 13.5 s per beam.The effective integration time is 6.0 s,and the new pulsars can be found in the fast region of this day,of which 122 are new pulsars in millisecond.Then we discuss the relationship between the observation ability of FAST and the observation time and frequency.In order to obtain the effect of the pulsar simulated by FAST on the whole,we use the evolve script to do the simulation again.The spin evolution samples of isolated normal pulsars in the Milky way are obtained,the parameters of the telescope are consistent with the above.711 new normal pulsars can be detected in the whole sky range of fast,and last we will put the FAST survey results on the-?diagram to study their.Mass is one of the most important parameters in the physical parameters of neutron star.It can not only reflect the structure of neutron star,the equation of state,the composition of nuclear matter,but also infer the evolution mechanism of neutron star.We find 72 neutron stars with measured mass in the galaxy We have counted 72 neutron stars with measured mass in 63 pairs of binary systems in the galaxy,in this paper,including 9 pairs of double neutron star systems?DNSs?,32 pairs of neutron star white dwarfs systems?NSWDs?,and 4 pairs of neutron star main sequence star system?NSMSs?,11 pairs of high mass X-ray binary systems?HMXBs?,5 pairs of low mass X-ray binary systems?LMXBs?,and 2 pairs of X ray systems?XBs?.In order to reduce the influence of the uncertainty of measurement mass,we use Monte Carlo method to simulate the mass distribution of each NS.Through the statistical study of 72 NS mass,we found that the mass distribution of ns has a bimodal structure,which may indicate that there are two birth modes of NS.The large mass peak distribution of NS may be produced by supernova explosion,and its theoretical birth mass is 1.4 M_?.The distribution of small mass peaks may be due to the collapse of white dwarfs after electron capture,with a mass of about 1.25 M_?.The different distribution characteristics of DNS and other types of NS indicate that the evolution of DNS may be different.In order to further study the characteristics of neutron star mass distribution,We divided 61 ns measured into the spin cycle into two classes of the millisecond neutron star?MSP?and the normal neutron star?PSR?at 20 ms.It is found that although the two kinds of NS can fit the bimodal,the PSR has no obvious bimodal structure,which is about larger than the average mass of PSR.We are according to neutron star binary system the accretion theory,it indicates that after NS has accreted about 0.22M_?substance after birth,the neutron star spin will may reach millisecond order.According to the distribution in-picture of neutron star mass and period,the relation between mass and period is found to be M=1.4+?P/ms?^-3/2.