[1202.4901] Double Compact Objects I: The Significance Of The Common Envelope On Merger Rates

Authors: Michal Dominik, Krzysztof Belczynski, Christopher Fryer, Daniel Holz, Emanuele Berti, Tomasz Bulik, Ilya Mandel, Richard O'Shaughnessy

Date: 22 Feb 2012

Abstract: The development of gravitational wave observatories (Advanced LIGO/Virgo, Einstein Telescope) is proceeding apace, and the direct detection of gravitational waves should be imminent. The last decade of observational and theoretical developments in stellar and binary evolution provides us with improvements to the predictions from populations synthesis models. Among the most important revisions in the formation and evolution of double compact objects are: updated wind mass loss rates (allowing for stellar mass black holes up to 80 Msun), a realistic treatment of the common envelope phase (that can affect merger rates by 2--3 orders of magnitude), and a qualitatively new neutron star/black hole mass distribution (consistent with the observed "mass gap"). We present a parameter study with these major physical updates included, focusing on the most important factors that set the DCO merger rates. A few of our more interesting findings are: the binding energy of the envelope and our description of natal kicks from supernovae play an important role in determining the formation and merger rate of DCOs. Also, models incorporating delayed (SASI) supernovae do not agree with the observed NS/BH "mass gap", in accordance with our previous work. And, finally, we find enhanced rates for BH-BH mergers as compared to previous estimates, with an expectation of ~100 such mergers per year in Advanced LIGO/Virgo detectors (although this rate is sensitive to factors, such as the natal kick distribution). This is the first in a series of three papers. The second paper will study the merger rates of double compact objects as a function of cosmological redshift, star formation rate, and metallicity. In the third paper we will present the detection rates for future gravitational wave observatories, using up-to-date signal waveforms and sensitivity curves. (abridged)

abs pdf

Mar 06, 2012

1202.4901 (/preprints)
2012-03-06, 11:09 [edit]


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