Detection of Excess Hard X-ray Emission from the Group of Galaxies Hcg62

From the group of galaxies HCG62, we detected an excess hard X-ray emission in energies above ∼ 4 keV with ASCA . The excess emission is spatially extended up to ∼ 10′ from the group center, and somewhat enhanced toward north. Its spectrum can be represented by either a power-law of photon index 0.8–2.7, or a Bremsstrahlung of temperature > 6.3 keV. In the 2–10 keV range, the observed hard X-ray flux, (1.0 ± 0.3) × 10−12 erg cm−2 s−1, implies a luminosity of (8.0 ± 2.0) × 10 erg s−1 for a Hubble constant of 50 km s−1 Mpc−1. The emission is thus too luminous to be attributed to X-ray binaries in the member galaxies. We discuss possible origin of the hard X-ray emission. Subject headings: galaxies: clusters: individual (HCG62) — X-rays: galaxies — galaxies: evolution