Detection of excess hard X-ray emission from the group of galaxies HCG 62

We detected an excess of hard X-ray emission at energies above similar to 4 keV from the group of galaxies HCG 62 using data from the ASCA satellite. The excess emission is spatially extended up to similar to 10' from the group center and somewhat enhanced toward the north. Its spectrum can be represented by either a power law of photon index 0.8-2.7 or a bremsstrahlung of temperature greater than 6.3 keV. In the 2-10 keV range, the observed hard X-ray flux, (1.0 +/- 0.3) x 10(-12) ergs cm(-2) s(-1), implies a luminosity of (8.0 +/- 2.0) x 10(41) ergs 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 origins of the hard X-ray emission.