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THE DYNAMICAL EFFECTS OF WHITE DWARF BIRTH KICKS IN GLOBULAR STAR CLUSTERS

John M. FregeauKavli Institute for Theoretical Physics, UCSB, Santa Barbara, CA 93106, USA; [email protected]Harvey B. RicherDepartment of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, CanadaFrederic A. RasioDepartment of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USAJarrod R. HurleyCentre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia

2009en

ABI

Annotatsiya

Recent observations of the white dwarf (WD) populations in the Galactic globular cluster NGC 6397 suggest that WDs receive a kick of a fewkm s(-1) shortly before they are born. Using our MonteCarlo cluster evolution code, which includes accurate treatments of all relevant physical processes operating in globular clusters, we study the effects of the kicks on their host cluster and on the WD population itself. We find that in clusters whose velocity dispersion is comparable to the kick speed, WD kicks are a significant energy source for the cluster, prolonging the initial cluster core contraction phase significantly so that at late times the cluster core-to-half-mass radius ratio is a factor of up to similar to 10 larger than in the no-kick case. WD kicks thus represent a possible resolution of the large discrepancy between observed and theoretically predicted values of this key structural parameter. Our modeling also reproduces the observed trend for younger WDs to be more extended in their radial distribution in the cluster than older WDs.

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Identifikatorlar

DOI: 10.1088/0004-637x/695/1/l20

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