16 research outputs found
The Probability Distribution of Binary Pulsar Coalescence Rates. I. Double Neutron Star Systems in the Galactic Field
Estimates of the Galactic coalescence rate (R) of close binaries with two
neutron stars (NS-NS) are known to be uncertain by large factors (about two
orders of magnitude) mainly due to the small number of systems detected as
binary radio pulsars. We present an analysis method that allows us to estimate
the Galactic NS-NS coalescence rate using the current observed sample and,
importantly, to assign a statistical significance to these estimates and to
calculate the allowed ranges of values at various confidence levels. The method
involves the simulation of selection effects inherent in all relevant radio
pulsar surveys and a Bayesian statistical analysis for the probability
distribution of the rate. The most likely values for the total Galactic
coalescence rate (R_peak) lie in the range 2-60 per Myr depending on different
pulsar population models. For our reference model 1, where the most likely
estimates of pulsar population properties are adopted, we obtain R_tot =
8_{-5}^{+9} per Myr at a 68% statistical confidence level. The corresponding
range of expected detection rates of NS-NS inspiral are 3_{-2}^{+4}x10^{-3} per
yr for the initial LIGO and 18_{-11}^{+21} per yr for the advanced LIGO.Comment: 28 pages including 7 figures, minor revisions, accepted for
publication in the Astrophysical Journa
Compact Binary Coalescences in the Band of Ground-based Gravitational-Wave Detectors
As the ground-based gravitational-wave telescopes LIGO, Virgo, and GEO 600
approach the era of first detections, we review the current knowledge of the
coalescence rates and the mass and spin distributions of merging neutron-star
and black-hole binaries. We emphasize the bi-directional connection between
gravitational-wave astronomy and conventional astrophysics. Astrophysical input
will make possible informed decisions about optimal detector configurations and
search techniques. Meanwhile, rate upper limits, detected merger rates, and the
distribution of masses and spins measured by gravitational-wave searches will
constrain astrophysical parameters through comparisons with astrophysical
models. Future developments necessary to the success of gravitational-wave
astronomy are discussed.Comment: Replaced with version accepted by CQG
An increased estimate of the merger rate of double neutron stars from observations of a highly relativistic system
The merger of close binary systems containing two neutron stars should
produce a burst of gravitational waves, as predicted by the theory of general
relativity. A reliable estimate of the double-neutron-star merger rate in the
Galaxy is crucial in order to predict whether current gravity wave detectors
will be successful in detecting such bursts. Present estimates of this rate are
rather low, because we know of only a few double-neutron-star binaries with
merger times less than the age of the Universe. Here we report the discovery of
a 22-ms pulsar, PSR J0737-3039, which is a member of a highly relativistic
double-neutron-star binary with an orbital period of 2.4 hours. This system
will merge in about 85 Myr, a time much shorter than for any other known
neutron-star binary. Together with the relatively low radio luminosity of PSR
J0737-3039, this timescale implies an order-of-magnitude increase in the
predicted merger rate for double-neutron-star systems in our Galaxy (and in the
rest of the Universe).Comment: 6 pages, 2 figure
Binary and Millisecond Pulsars
We review the main properties, demographics and applications of binary and
millisecond radio pulsars. Our knowledge of these exciting objects has greatly
increased in recent years, mainly due to successful surveys which have brought
the known pulsar population to over 1700. There are now 80 binary and
millisecond pulsars associated with the disk of our Galaxy, and a further 103
pulsars in 24 of the Galactic globular clusters. Recent highlights have been
the discovery of the first ever double pulsar system and a recent flurry of
discoveries in globular clusters, in particular Terzan 5.Comment: 77 pages, 30 figures, available on-line at
http://www.livingreviews.org/lrr-2005-
The Evolution of Compact Binary Star Systems
We review the formation and evolution of compact binary stars consisting of
white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and
BHs are thought to be the primary astrophysical sources of gravitational waves
(GWs) within the frequency band of ground-based detectors, while compact
binaries of WDs are important sources of GWs at lower frequencies to be covered
by space interferometers (LISA). Major uncertainties in the current
understanding of properties of NSs and BHs most relevant to the GW studies are
discussed, including the treatment of the natal kicks which compact stellar
remnants acquire during the core collapse of massive stars and the common
envelope phase of binary evolution. We discuss the coalescence rates of binary
NSs and BHs and prospects for their detections, the formation and evolution of
binary WDs and their observational manifestations. Special attention is given
to AM CVn-stars -- compact binaries in which the Roche lobe is filled by
another WD or a low-mass partially degenerate helium-star, as these stars are
thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure
The Galactic Formation Rate of Eccentric Neutron Star-White Dwarf Binaries
In this paper we consider the population of eccentric binaries with a neutron star and a white dwarf that has been revealed in our galaxy in recent years through binary pulsar observations. We apply our statistical analysis method (Kim, Kalogera, & Lorimer 2003)and calculate the Galactic formation rate of these binaries empirically. We then compare our results with rate predictions based on binary population synthesis from various research groups and for various ranges of model input parameters. For our reference moel, we find the Galactic formation rate of these eccentric systems to be ~7 per Myr, about an order of magnitude smaller than results from binary evolution estimations. However, the empirical estimates are calculated with no correction for pulsar beaming, and therefore they should be taken as lower limits. Despite uncertainties that exceed an order of magnitude, there is significant overlap of the various rate calculations. This consistency lends confidence that our current understanding of the formation of these eccentric NS-WD binaries is reasonable