X‐Ray Emission from the Fornax Cluster

The Astrophysical Journal1997Vol. 482(1), pp. 143–155

Citations Over TimeTop 10% of 1997 papers

C. Jones, C. P. Stern, W. Forman, J. Breen, L. P. David, W. Tucker, Marijn Franx

Abstract

We have analyzed the ROSAT PSPC observations of the central region of the Fornax cluster, a relatively poor group of galaxies at a distance of about 24 Mpc. The brightest X-ray and optical galaxy in the group is NGC 1399, an E1 galaxy located near the center of the Fornax cluster. We characterize the hot gas around the galaxy, derived from a 2' to 18' annulus around NGC 1399, as having a mean temperature of 1.30 ± 0.05 keV and a heavy element abundance of 0.6 ± 0.1 with respect to solar abundance (Fe/H = 4.68 × 10-5 by number). Spatially resolved spectral data provide both gas temperature and gas abundance profiles extending to 125 kpc (18') from the galaxy. The temperature distribution, combined with the X-ray surface brightness profile, yields an accurate determination of the gravitating mass within 125 kpc, which falls in the range (4.3-8.1) × 1012 M☉ (95% confidence range, including systematic uncertainties). If we include the extended optical halo around NGC 1399, the mass-to-light ratio increases with radius from 33 ± 8 M☉/L☉ at 18 kpc to 70 ± 22 M☉/L☉ at 110 kpc. We compare the heavy element abundance distribution measured around NGC 1399 with that measured around the Virgo galaxy NGC 4472, as well as to models for hot coronae. We find that the abundance distribution is in good agreement with that previously measured for NGC 4472 by Forman et al. in 1993. For both galaxies, the observed abundance profiles require both a weak evolution of the type Ia supernova rate with time and a present epoch rate which agrees with that of Cappellaro et al.

Citations Over TimeTop 10% of 1997 papers

Abstract

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