Discovery of the Candidate Off-nuclear Ultrasoft Hyper-luminous X-ray Source 3XMM J141711.1+522541

Understand

We report the discovery of an off-nuclear ultrasoft hyper-luminous X-ray source candidate 3XMM J141711.1+522541 in the inactive S0 galaxy SDSS J141711.07+522540.8 (z=0.41827, d_L=2.3 Gpc) in the Extended Groth Strip.

• It is located at a projected offset of ~1.0 (5.2 kpc) from the nucleus of the galaxy and was serendipitously detected in five XMM-Newton observations in 2000 July.
• Two observations have enough counts and can be fitted with a standard thermal disk with an apparent inner disk temperature kT_MCD ~ 0.13 keV and a 0.28-14.2 keV unabsorbed luminosity L_X ~ 4X10^{43} erg/s in the source rest frame.
• The source was still detected in three Chandra observations in 2002 August, with similarily ultrasoft but fainter spectra (kT_MCD ~ 0.17 keV, L_X ~ 0.5X10^{43} erg/s).