NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-07-20 T02:16:27 PDT
Help | Comment | NED Home

For refcode 1993ApJ...415L..17L:
Retrieve 41 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
1993ApJ...415L..17L THE RELATION BETWEEN VELOCITY DISPERSION AND TEMPERATURE IN CLUSTERS: LIMITING THE VELOCITY BIAS LORI M. LUBIN AND NETA A. BAHCALL Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001 Received 1993 March 3; accepted 1993 July 2 ABSTRACT The observed galaxy velocity dispersion in clusters of galaxies is compared with the X-ray temperature of the intracluster gas for a large sample of clusters. A strong correlation is found between the observables which is best fitted by the relation {sigma} = 332 + 52(kT)^0.6+/-0.1^ km s^-1^; here {sigma} is the rms radial velocity dispersion in the cluster, and kT is the gas temperature in keV. The relation is consistent with that expected from an isothermal model where both the gas and the galaxies are in hydrostatic equilibrium with the binding cluster potential, i.e., {sigma} is proportional to T^0.5^. The observed relation is used to determine the best-fit average {beta} parameter for clusters, {beta} = {sigma}^2^/(kT/{mu}m_p_), which describes the ratio of energy per unit mass in the galaxies to that in the gas (where {mu}m_p_ is the mean particle mass); we find {beta} = 0.94 +/- 0.08 [ and {beta}(median) = 0.98]. This implies that the galaxies and the gas trace the same cluster potential with approximately equal energy per unit mass (i.e., {beta} = 1). The best-fit observed {beta} also suggests that no significant velocity bias exists in clusters of galaxies, i.e., the galaxy velocity dispersion in clusters is a fair tracer of the dark matter velocity dispersion. The best-fit velocity bias is b_{nu} = {sigma}_gal_/{sigma}_DM_ ~ {beta}^0.5^ = 0.97 +/- 0.04 (with b_{nu}_ = 1 corresponding to no bias). Subject headings: dark matter - galaxies: clustering - X-rays: galaxies
Retrieve 41 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home