Herschel/HerMES: the X-ray-infrared correlation for star-forming galaxies at z similar to 1
Résumé
For the first time, we investigate the X-ray/infrared (IR) correlation for star-forming galaxies (SFGs) at z similar to 1, using SPIRE submm data from the recently launched Herschel Space Observatory and deep X-ray data from the 2-Ms Chandra Deep Field-North survey. We examine the X-ray/IR correlation in the soft X-ray (SX; 0.5-2 keV) and hard X-ray (HX; 2-10 keV) bands by comparing our z similar to 1 SPIRE-detected SFGs to equivalently IR-luminous (L-IR \textgreater 10(10) L-circle dot) samples in the local/low-redshift Universe. Our results suggest that the X-ray/IR properties of the SPIRE SFGs are on average similar to those of their local counterparts, as we find no evidence for evolution in the L-SX/L-IR and L-HX/L-IR ratios with redshift. We note, however, that at all redshifts, both L-SX/L-IR and L-HX/L-IR are strongly dependent on IR luminosity, with luminous and ultraluminous IR galaxies (LIRGs and ULIRGs; L-IR \textgreater 10(11) L-circle dot) having up to an order of magnitude lower values than normal IR galaxies (L-IR \textless 10(11) L-circle dot). We derive a L-SX-L-IR relation and confirm the applicability of an existing L-HX-L-IR relation for both local and distant LIRGs and ULIRGs, consistent with a scenario where X-ray luminosity is correlated with the star formation rate.