Thursday, July 4, 2013

1307.0959 (N. Mennekens et al.)

Massive double compact object mergers: gravitational wave sources and r-process-element production sites    [PDF]

N. Mennekens, D. Vanbeveren
With our galactic evolutionary code that contains a detailed intermediate mass and massive binary population model, we study the temporal evolution of the galactic population of double neutron star binaries, mixed systems with a neutron star and black hole component and double black hole binaries. We compute the merger rates of these relativistic binaries and we translate them into LIGO II detection rates. Contrary to simulations made by other research groups, we find that this detection rate will not be dominated by double black hole mergers. The reason is the possible effect of large stellar wind mass loss during the luminous blue variable phase of a star with initial mass larger than 40 Mo when such a star is a binary component. Hydrodynamic computations of r-process chemical yields ejected during the relativistic binary merger process have recently become available. With our galactic code that includes binaries it is then straightforward to calculate the temporal galactic evolution of the r-process elements ejected by these mergers. We conclude that except for the earliest evolutionary phase of the Galaxy (~the first 100 Myr) double compact star mergers may be the major production sites of r-process elements and it is probable that the mixed systems dominate over double neutron star binary mergers.
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