A sample of X-ray emitting normal galaxies from the BMW–HRI Catalogue

¹ INAF – Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy e-mail: tajer@brera.mi.astro.it
² Università di Milano – Bicocca, Dipartimento di Fisica, P.za della Scienza 3, 20126 Milano, Italy

Received: 23 June 2004
Accepted: 16 December 2004

Abstract

We obtained a sample of 143 normal galaxies with X-ray luminosity in the range  erg s^-1 from the cross-correlation of the ROSAT HRI Brera Multi-scale Wavelet (BMW–HRI) Catalogue with the Lyon-Meudon Extragalactic Database (LEDA). We find that the average X-ray properties of this sample are in good agreement with those of other samples of galaxies in the literature. We selected a complete flux limited serendipitous sample of 32 galaxies from which we derived the distribution of normal galaxies in the flux range  erg cm^-2 s^-1. The resulting distribution is consistent with the Euclidean -1.5 slope. Comparisons with other samples, such as the Extended Medium Sensitivity Survey, the ROSAT All Sky Survey, the XMM-Newton/2dF survey, and the Chandra Deep Field Survey indicate that the distribution of normal galaxies is consistent with a Euclidean slope over a flux range of about 6 decades.