Oviin Elliptical Galaxies: Indicators of Cooling Flows
- 20 December 2005
- journal article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 635 (2) , 1031-1043
- https://doi.org/10.1086/497421
Abstract
Early-type galaxies often contain a hot X-ray emitting interstellar medium (3-8E6 K) with an apparent radiative cooling time much less than a Hubble time. If unopposed by a heating mechanism, the gas will radiatively cool to temperatures <= 10E4 K at a rate proportional to L_X/T_X, typically 0.03-1 M_solar yr^-1. We can test if gas is cooling through the 3E5 K range by observing the OVI doublet, whose luminosity is proportional to the cooling rate. Here we report on a study of an unbiased sample of 24 galaxies, obtaining Far Ultraviolet Spectroscopic Explorer spectra to complement the X-ray data of ROSAT} and Chandra. The OVI line emission was detected in about 40% of the galaxies and at a luminosity level similar to the prediction from the cooling flow model. There is a correlation between Mdot_OVI and Mdot_X, although there is significant dispersion about the relationship, where the OVI is brighter or dimmer than expected by a factor of three or more. If the cooling flow picture is to be retained, this dispersion requires that cooling flows be time-dependent, as might occur by the activity of an AGN. However, of detected objects, those with the highest or lowest values of Mdot_OVI/Mdot_X are not systematically hot or cool, as one might predict from AGN heating.Comment: 49 pages, 26 figures, ApJ, in presKeywords
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This publication has 26 references indexed in Scilit:
- Mid‐Infrared Observation of Mass Loss in Elliptical GalaxiesThe Astrophysical Journal, 2002
- The Detection of a Cooling Flow Elliptical Galaxy from O [CSC]vi[/CSC] EmissionThe Astrophysical Journal, 2001
- The Effect of Environment on the X‐Ray Emission from Early‐Type GalaxiesThe Astrophysical Journal, 2000
- X-Ray Emission from Early-Type Galaxies: A Complete Sample Observed by [ITAL]ROSAT[/ITAL]The Astrophysical Journal, 1998
- A Far‐Ultraviolet Analysis of the Stellar Populations in Six Elliptical and S0 GalaxiesThe Astrophysical Journal, 1997
- The insignificance of 'heating flows' in 'cooling flow' clusters of galaxiesThe Astrophysical Journal, 1993
- Interstellar matter in early-type galaxies. II - The relationship between gaseous components and galaxy typesThe Astrophysical Journal, 1992
- Evolution of the interstellar medium in elliptical galaxies. II - X-ray propertiesThe Astrophysical Journal, 1991
- H I in the GalaxyAnnual Review of Astronomy and Astrophysics, 1990
- Highly ionized atoms in cooling gasThe Astrophysical Journal, 1986