2007MNRAS.380..691D -
Mon. Not. R. Astron. Soc., 380, 691-702 (2007/September-2)
Millisecond pulsars around intermediate-mass black holes in globular clusters.
DEVECCHI B., COLPI M., MAPELLI M. and POSSENTI A.
Abstract (from CDS):
Globular clusters (GCs) are expected to be breeding grounds for the formation of single or binary intermediate-mass black holes (IMBHs) of ≳100M☉, but a clear signature of their existence is still missing. In this context, we study the process of dynamical capture of a millisecond pulsar (MSP) by a single or binary IMBH, simulating various types of single-binary and binary-binary encounters. It is found that [IMBH, MSP] binaries form over cosmic time in a cluster, at rates ≲10–11/yr, via encounters of wide-orbit binary MSPs off the single IMBH, and at a lower pace, via interactions of (binary or single) MSPs with the IMBH orbited by a typical cluster star. The formation of an [IMBH, MSP] system is strongly inhibited if the IMBH is orbited by a stellar mass black hole (BH): in this case, the only viable path is through the formation of a rare stable hierarchical triplet with the MSP orbiting exterior to the [IMBH, BH] binary. The [IMBH, MSP] binaries that form are relatively short-lived, ≲108-109 yr, since their orbits decay via emission of gravitational waves. The detection of an [IMBH, MSP] system has a low probability of occurrence, when inferred from the current sample of MSPs in GCs. If next-generation radio telescopes, like Square Kilometre Array (SKA), will detect an order of magnitude larger population of MSP in GCs, at least one [IMBH, MSP] is expected. Therefore, a complete search for low-luminosity MSPs in the GCs of the Milky Way with SKA will have the potential of testing the hypothesis that IMBHs of the order of 100M☉ are commonly hosted in GCs. The discovery will unambiguously prove that BHs exist in the still uncharted interval of masses around ≳100M☉.
Abstract Copyright:
2007 The Authors. Journal compilation © 2007 RAS
Journal keyword(s):
black hole physics - stellar dynamics - stars: neutron - pulsars: general - globular clusters: general
Simbad objects:
10
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