On the Existence of Pulsars in the Vicinity of the Massive Black Hole in the Galactic Center

Abstract

Pulsars, if existing and detectable in the immediate vicinity of the massive black hole (MBH) in the Galactic center (GC), may be used as a superb tool to probe both the environment and the metric of the central MBH. The recent discovery of a magnetized pulsar in the GC suggests that many more pulsars should exist near the MBH. In this paper, we estimate the number and the orbital distribution of pulsars in the vicinity of the MBH in the GC by assuming that the pulsar progenitors, similar to the GC S-stars, were captured to orbits tightly bound to the MBH through the tidal breakup of stellar binaries. We use the current observations on both the GC S-stars and the hypervelocity stars to calibrate the injection rate(s) of and the dynamical model(s) for the stellar binaries. By including the relaxation processes, supernova kicks, and gravitational wave radiation in our simulations, we estimate that ~97-190 (9-14) pulsars may presently orbit the central MBH with semimajor axes <=4000AU (<=1000AU), which is compatible with the current observational constraints on the number of the GC pulsars. The semimajor axis and the pericenter distance of the pulsar closest to the central MBH are probably in the range of ~120-460AU and ~2-230AU, respectively. Future telescopes, such as the SKA, may be able to detect a significant number of pulsars with semimajor axis smaller than a few thousand AU in the GC. Long-term monitoring of these pulsars would be helpful in constraining both the environment and the metric of the central MBH. Our preferred model also results in about ten hyperfast pulsars with velocity >~1500km/s moving away from the Milky Way.

9 pages, 3 figures, accepted for publication in the Astrophysical Journal

References in corpus (5)

• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• The different progenitors of type Ib, Ic SNe, and of GRB
• Dynamical evolution of the young stars in the Galactic center: N-body simulations of the S-stars
• Origin of the S Stars in the Galactic Center
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• Probing the spinning of the massive black hole in the Galactic Center via pulsar timing: A Full Relativistic Treatment
• On the Newtonian and Spin-induced Perturbations felt by the Stars Orbiting around the Massive Black Hole in the Galactic Center
• An 86-GHz search for Pulsars in the Galactic Center with the Atacama Large Millimeter/submillimeter Array
• Spin dynamics of a millisecond pulsar orbiting closely around a massive black hole
• Post-Keplerian perturbations of the orbital time shift in binary pulsars: an analytical formulation with applications to the Galactic Center
• Prospects for Constraining the Yukawa Gravity with Pulsars around Sagittarius A*
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• On Detecting Nearby Nano-Hertz Gravitational Wave Sources via Pulsar Timing Arrays
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• Relativistic time delay analysis of pulsar signals near ultra-compact objects
• Prospects for probing small-scale dark matter models with pulsars around Sagittarius A*
• Another Approach to Test Gravity around a Black Hole
• Measuring the Spin of the Galactic Center Supermassive Black Hole with Two Pulsars
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