We explore the nature of Infrared Excess sources ( IRX ) , which are proposed as candidates for luminous [ L _ { X } ( 2 - 10 keV ) > 10 ^ { 43 } erg s ^ { -1 } ] Compton Thick ( N _ { H } > 2 \times 10 ^ { 24 } cm ^ { -2 } ) QSOs at z \approx 2 .
Lower redshift , z \approx 1 , analogues of the distant IRX population are identified by firstly redshifting to z = 2 the SEDs of all sources with secure spectroscopic redshifts in the AEGIS ( 6488 ) and the GOODS-North ( 1784 ) surveys and then selecting those that qualify as IRX sources at that redshift .
A total of 19 galaxies are selected .
The mean redshift of the sample is z \approx 1 .
We do not find strong evidence for Compton Thick QSOs in the sample .
For 9 sources with X-ray counterparts , the X-ray spectra are consistent with Compton Thin AGN .
Only 3 of them show tentative evidence for Compton Thick obscuration .
The SEDs of the X-ray undetected population are consistent with starburst activity .
There is no evidence for a hot dust component at the mid-infrared associated with AGN heated dust .
If the X-ray undetected sources host AGN , an upper limit of L _ { X } ( 2 - 10 keV ) = 10 ^ { 43 } erg s ^ { -1 } is estimated for their intrinsic luminosity .
We propose that a large fraction of the z \approx 2 IRX population are not Compton Thick QSOs but low luminosity [ L _ { X } ( 2 - 10 keV ) < 10 ^ { 43 } erg s ^ { -1 } ] , possibly Compton Thin , AGN or dusty starbursts .
It is shown that the decomposition of the AGN and starburst contribution to the mid-IR is essential for interpreting the nature of this population , as star-formation may dominate this wavelength regime .