The Nature of Luminous X-Ray Sources with Mid-Infrared Counterparts Academic Article uri icon


  • We investigate the luminous X-ray sources in the Lockman Hole (LH) and the extended Groth strip (EGS) detected at 24 m using the Multiband Imaging Photometer (MIPS) and also with the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope. We assemble optical/infrared spectral energy distributions (SEDs) for 45 X-ray/24 m sources in the EGS and LH. Only about one-quarter of the hard X-ray/24 m sources show pure type 1 active galactic nucleus (AGN) SEDs. More than half of the X-ray/24 m sources have stellar emission-dominated or obscured SEDs, similar to those of local type 2 AGN and spiral/starburst galaxies. One-third of the sources detected in hard X-rays do not have a 24 m counterpart. Two such sources in the LH have SEDs resembling those of S0/elliptical galaxies. The broad variety of SEDs in the optical-to-Spitzer bands of X-ray-selected AGNs means that AGNs selected according to the behavior in the optical/infrared will have to be supplemented by other kinds of data (e.g., X-ray) to produce unbiased samples of AGNs.

published proceedings

  • The Astrophysical Journal Supplement Series

author list (cited authors)

  • Alonso-Herrero, A., Prez-Gonzlez, P. G., Rigby, J., Rieke, G. H., Le Floch, E., Barmby, P., ... Wilson, G.

citation count

  • 33

complete list of authors

  • Alonso-Herrero, A||Pérez-González, PG||Rigby, J||Rieke, GH||Le Floc’h, E||Barmby, P||Page, MJ||Papovich, C||Dole, H||Egami, E||Huang, J-S||Rigopoulou, D||Cristóbal-Hornillos, D||Eliche-Moral, C||Balcells, M||Prieto, M||Erwin, P||Engelbracht, CW||Gordon, KD||Werner, M||Willner, SP||Fazio, GG||Frayer, D||Hines, D||Kelly, D||Latter, W||Misselt, K||Miyazaki, S||Morrison, J||Rieke, MJ||Wilson, G

publication date

  • September 2004