Chandra view of the dynamically young cluster of galaxies A1367 II. point sources

Abstract

A 40 ks \emph{Chandra} ACIS-S observation of the dynamically young cluster A1367 yields new insights on X-ray emission from cluster member galaxies. We detect 59 point-like sources in the ACIS field, of which 8 are identified with known cluster member galaxies. Thus, in total 10 member galaxies are detected in X-rays when three galaxies discussed in paper I (Sun & Murray 2002; NGC 3860 is discussed in both papers) are included. The superior spatial resolution and good spectroscopy capability of \chandra allow us to constrain the emission nature of these galaxies. Central nuclei, thermal halos and stellar components are revealed in their spectra. Two new low luminosity nuclei (LLAGN) are found, including an absorbed one (NGC 3861). Besides these two for sure, two new candidates of LLAGN are also found. This discovery makes the LLAGN/AGN content in this part of A1367 very high ($\gsim$ 12%). Thermal halos with temperatures around 0.5 - 0.8 keV are revealed in the spectra of NGC 3842 and NGC 3837, which suggests that Galactic coronae can survive in clusters and heat conduction must be suppressed. The X-ray spectrum of NGC 3862 (3C 264) resembles a BL Lac object with a photon index of $\sim$ 2.5. We also present an analysis of other point sources in the field and discuss the apparent source excess ($\sim$ 2.5 $σ$) in the central field.