Binary radio pulsars in globular clusters: their orbital eccentricities and interaction with other stars
Alak Ray
Tata Institute of Fundamental Research
Sustained high sensitivity searches of globular clusters (GC) for
radio pulsars by improved pulsar search algorithms and pulsar timing
experiments have yielded some 140 pulsars in more than two dozen GCs. The
observed distribution of orbital eccentricity and period of binary
radio pulsars in GCs have signatures which appear to be from the past
imprint of the interaction between single pulsars and binary systems
or of binary pulsars and single passing normal stars that includes
exchange and merger of stars. It is seen that GCs have different groups
of pulsars arising from separate interaction or evolutionary scenarios.
We analyse these distributions using computational tools like the STARLAB
software. The corresponding distribution for galactic field pulsars show
notable difference from the GC pulsar orbital period and eccentricity
distribution. The long orbital period pulsars in the galactic field
with frozen out low eccentricities are missing in globular clusters and
we show that ionization alone of these systems in GCs cannot account
for the peculiarities. Some of the short orbital period systems will
undergo merger due to gravitational wave radiation and will be a source
of gamma-ray bursts if both stars are neutron stars in a binary.
I will also discuss the observable signatures associated with one of the
proposed formation scenario for the highly eccentric binary millisecond
pulsar PSR J1903+0327 in terms of a hierarchical triplet and argue that if
it originated in a GC, then the set of such GCs will have to be somewhat
restricted in their properties.
Date: | Lundi, le 25 mai 2009 |
Heure: | 15:00 |
Lieu: | Université McGill |
| Ernest Rutherford Physics Building, R.E. Bell Conference Room (room 103) |
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