Characterizing the Present Day Spatial Distribution of Nearby Neutron Stars
Dr. Peter Gonthier, Hope College
We developed a model describing the present day spatial distribution of nearby neutron stars as part of a larger project aimed at replacing our Monte Carlo-based pulsar simulation with one implementing the Maximum Likelihood Method. This new program will enable us to produce confidence regions on the parameter space of a model of the population statistics of radio and gamma-ray pulsars, which we will use to study different high energy emission beam geometry and luminosity models. Our project supports the team efforts of NASA’s Fermi Gamma-ray Space Telescope, launched in 2008, which has discovered about 80 new gamma-ray pulsars and almost 2,000 new radio pulsars. We assume in our Monte Carlo program a recently improved surface density distribution of neutron stars born in the Galaxy with an empirical supernova kick-velocity model. Using Monte Carlo techniques, we seed the Galaxy assuming a constant birth rate during the past billion years, and evolve the neutron star trajectories from their birth location to present. Having generated a large sample of simulated neutron stars within 12 kiloparsecs from the Sun, we explore spatial distribution models using nonlinear least squares fitting procedures. We present some preliminary results from our efforts this past summer, and our future plans to characterize the likelihood function to be maximized.
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