We report the detection of X-ray emission from the hyperluminous infrared galaxy IRAS F15307+3252 at z = 0.93 and its properties obtained from XMM-Newton observations .
Although the X-ray emission is very faint and the data are noisy , a prominent line-like feature in the observed 3–4 keV range is inferred from both photometric and spectroscopic techniques .
It indicates an X-ray spectrum dominated by 6.4 keV Fe K \alpha emission and the presence of a Compton-thick AGN .
Our estimate of the luminosity of the illuminating source ( L _ { 2 - 10 keV } \geq 1 \times 10 ^ { 45 } erg s ^ { -1 } ) , required to produce the observed Fe K \alpha emission in reflection from cold matter , means that the hidden quasar nucleus accounts for a significant fraction of the large bolometric luminosity .
The soft X-ray emission below 2 keV is found to be spatially extended and probably of a separate origin .
The temperature and bolometric luminosity ( kT \simeq 2 keV and L _ { bol } ^ { CL } \simeq 1 \times 10 ^ { 44 } erg s ^ { -1 } ) obtained from a thermal spectrum place this X-ray source on the L - T _ { X } relation of galaxy clusters .
The possible association with a galaxy cluster can be added to the list of remarkable similarities between IRAS F15307+3252 and another hyperluminous infrared galaxy IRAS 09104+4109 ( z = 0.44 ) , both of which have bolometric luminosities dominated by hidden quasar nuclei .
Our result on IRAS F15307+3252 illustrates how difficult it is to detect Compton thick Type II quasars at z = 1 , particularly if their bolometric outputs do not rival the hyperluminous population .