The dark haloes of early-type galaxies in low-density environments: XMM-Newton and Chandra observations of NGC 57, NGC 7796 and IC 1531 - AstrophysicsReport as inadecuate




The dark haloes of early-type galaxies in low-density environments: XMM-Newton and Chandra observations of NGC 57, NGC 7796 and IC 1531 - Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We present analysis of Chandra and XMM-Newton observations of threeearly-type galaxies, NGC 57, NGC 7796 and IC 1531. All three are found in verylow density environments, and appear to have no neighbours of comparable size.NGC 57 has a halo of kT~0.9 keV, solar metallicity gas, while NGC 7796 and IC1531 both have ~0.55 keV, 0.5-0.6 Zsol haloes. IC 1531 has a relatively compacthalo, and we consider it likely that gas has been removed from the system bythe effects of AGN heating. For NGC 57 and NGC 7796 we estimate mass, entropyand cooling time profiles and find that NGC 57 has a fairly massive dark halowith a mass-to-light ratio of 44.7 4.0,-8.5 Msol-Lsol 1 sigma uncertaintiesat 4.75 Re. This is very similar to the mass-to-light ratio found for NGC 4555and confirms that isolated ellipticals can possess sizable dark matter haloes.We find a significantly lower mass-to-light ratio for NGC 7796, 10.6+2.5,-2.3 Msol-Lsol at 5 Re, and discuss the possibility that NGC 7796 hostsa galactic wind, causing us to underestimate its mass.



Author: E. O'Sullivan, A.J.R. Sanderson, T.J. Ponman

Source: https://arxiv.org/







Related documents