SIMBAD references

2005ApJ...635.1031B - Astrophys. J., 635, 1031-1043 (2005/December-3)

O VI in elliptical galaxies: indicators of cooling flows.


Abstract (from CDS):

Early-type galaxies often contain a hot X-ray-emitting interstellar medium [(3-8)x106 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 ≲104 K at a rate proportional to LX/TX, typically 0.03-1 M/yr. We can test whether gas is cooling through the 3x105 K range by observing the O VI 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 O VI 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 M{dot}_OVI_and M{dot}X, although there is significant dispersion about the relationship, where the O VI is brighter or dimmer than expected by a factor of 3 or more. If the cooling flow picture is to be retained, then 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 M{dot}_OVI/M{dot}X_are not systematically hot or cool, as one might predict from AGN heating.

Abstract Copyright:

Journal keyword(s): Galaxies: Cooling Flows - Galaxies: ISM - Ultraviolet: Galaxies - X-Rays: Galaxies

Status at CDS:  

Simbad objects: 25

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