Pulsar Surveys Simulation

Radio surveys are the most successful method for discovering new pulsars. We first reviewed the main factors affecting sensitivities of pulsar searches in radio bands. These factors can be grouped into two categories. First, the instrumental factors include telescope size, observation frequency, observation bandwidth, integration time, sampling rate, digitization loss, and system temperature. Second, the intrinsic properties of pulsars include dispersion, period, and effective pulse width.We summarized the results of existing radio pulsar surveys. The most successful pulsar survey so far is Parkes multibeam pulsar survey(PKSMB), which published 1086 new pulsars. The PKSMB was expanded by two more surveys, namely, Parkes-Swinbume multibeam survey(PKSSW) and Parkes high-latitude multibeam pulsar survey(PKSHL). The three surveys discovered a total of 1377 pulsars.We utilized the software package PsrPopPy, which adopts a time evolution model of pulsar parameters, to simulate the Galactic pulsar distribution. The results of Parkes multibeam pulsar survey and its two extensions were used as inputs of PsrPopPy to constrain the parameters of pulsar population. We tuned PsrPopPy to generate a simulated Galactic pulsar population and its distribution in the Galaxy.We looked into the impacts of nearby neutron stars on Earth-based high energy physics experiments, particularly those based on positron detections. The excess of positron has been suggested as one evidence for the existence of dark matter. We examined the pulsar population of the solar neighborhood through the PsrPopPy simulations described above. Within 1kpc of the Sun, we predicted that there exist 600 pulsars, 13 of which can be Gamma ray pulsars. This population of nearby high energy pulsars should play an important role in revealing the origin of the rising cosmic ray positron fraction.The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will begin its early-science operations during 2016. Drift-scan pulsar surveys will be carried out during its early science operations using an ultra-wide-band receiver system(covering ~ 270 to 1620 MHz). Previously published work relating to FAST pulsar surveys did not consider this early science period, in particular, the optimized utilities of such an ultra-wide band.We thus provided here an in-depth description of the early science capabilities of FAST, described optimal algorithms searching for pulsars using FAST early-science systems, and estimated the expected pulsar discoveries by FAST in globular clusters. In addition, we have developed new software that simulated wide-band, drift-scan pulsar observations. We applied the SIGPROC search software to the simulated data sets to determine the expected sensitivity of the FAST surveys.We find that one representative FAST drift-scan observation would achieve a flux sensitivity of ~ 40 μJy. Our results showed that a single FAST drift-scan(lasting less than a minute) is likely to find at least one pulsar in four globular clusters. Repeated observations will increase the likely number of detections. We found that pulsars in ~10 clusters are likely to be found if the data from 10 drift-scan observations of each cluster are incoherently combined.