X-rays from the Type II quasar in the hyperluminous infrared galaxy IRAS F15307+3252★

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 Kα emission and the presence of a Compton-thick active galactic nucleus. Our estimate of the luminosity of the illuminating source (L 2‐10 keV 1 × 10 45 erg s −1 ), required to produce the observed Fe Kα 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 � 2k eVand L CL � 1 × 10 44 erg s −1 ) obtained from a thermal spectrum place this X-ray source on the L‐TX 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.

[1]  A. Fabian,et al.  Chandra detection of reflected X‐ray emission from the type 2 QSO in IRAS 09104+4109 , 2000, astro-ph/0011518.

[3]  M. Basko.  K-fluorescence lines in spectra of X-ray binaries , 1978 .

[4]  Dan McCammon,et al.  Interstellar photoelectric absorption cross-sections, 0.03-10 keV , 1983 .

[5]  The environments of hyperluminous infrared galaxies at 0.44 < z < 1.55 , 2003, astro-ph/0312215.

[6]  E. Peeters,et al.  Polycyclic Aromatic Hydrocarbons as a Tracer of Star Formation? , 2004 .

[7]  D. Sanders,et al.  LUMINOUS INFRARED GALAXIES , 1996 .

[8]  M. Norman,et al.  Nonlinear Hydrodynamics of Cosmological Sheets. II. Fragmentation and the Gravitational, Cooling, and Thin-Shell Instabilities , 1995 .

[9]  The FIRST Sample of Ultraluminous Infrared Galaxies at High Redshift. I. Sample and Near-Infrared Morphologies , 2000, astro-ph/0006003.

[10]  M. Enoki,et al.  Relations between Galaxy Formation and the Environments of Quasars , 2003 .

[11]  R. Cutri,et al.  IRAS F15307+3252: A Hyperluminous Infrared Galaxy at Z = 0.93 , 1994 .

[12]  S. G. Kleinmann,et al.  The Properties and Environment of the Giant, Infrared-Luminous Galaxy IRAS 09104+4109 , 1988 .

[13]  M. Rowan-Robinson,et al.  Hyperluminous infrared galaxies , 1999 .

[14]  Andrew C. Fabian,et al.  X-ray reflection from cold matter in Active Galactic Nuclei and X-ray binaries , 1991 .

[15]  W. Brandt,et al.  X-ray emission from the field of the hyperluminous IRAS galaxy IRASF15307+3252 , 1996 .

[16]  G. Palumbo,et al.  X-ray astronomy : stellar endpoints, AGN, and the diffuse X-ray background , 2001 .

[17]  ASCA Compilation of X-Ray Properties of Hot Gas in Elliptical Galaxies and Galaxy Clusters: Two Breaks in the Temperature Dependences , 2004, astro-ph/0411745.

[18]  Richard L. White,et al.  The FIRST Survey: Faint Images of the Radio Sky at twenty centimeters , 1995 .

[19]  W. Brandt,et al.  Limits on the X-ray emission from several hyperluminous IRAS galaxies , 1998, astro-ph/9808324.

[20]  R. Cutri,et al.  XMM—Newton observations of two hyperluminous IRAS galaxies: Compton-thick quasars with obscuring starbursts , 2002, astro-ph/0211166.

[21]  G. Neugebauer,et al.  Near-Infrared Observations of FSC 15307+3252 , 1994 .

[22]  Institute of Theoretical Astrophysics,et al.  Radio-quiet quasar environments at 0.5 < z < 0.8 , 2000, astro-ph/0011394.

[23]  G. Neugebauer,et al.  Ultraluminous infrared galaxies and the origin of quasars , 1988 .

[24]  R. McMahon,et al.  Hubble Space Telescope Wide Field Planetary Camera 2 observations of hyperluminous infrared galaxies , 2002 .

[25]  J. Dickey,et al.  H I in the Galaxy , 1990 .

[26]  Astrophysics,et al.  Clustering of galaxies around radio quasars at 0.5≤ z ≤0.8 , 1999, astro-ph/9912070.

[27]  W. Brandt,et al.  ASCA Observations of Two Ultraluminous IRAS Galaxies: IRAS 15307+3252 and IRAS 20460+1925 , 1997 .

[28]  Observations of hyperluminous infrared galaxies with the Infrared Space Observatory: implications for the origin of their extreme luminosities , 2002, astro-ph/0204524.

[29]  Ralf Bender,et al.  THE SLOPE OF THE BLACK HOLE MASS VERSUS VELOCITY DISPERSION CORRELATION , 2002, astro-ph/0203468.

[30]  Duane A. Liedahl,et al.  New Calculations of Fe L-Shell X-Ray Spectra in High-Temperature Plasmas , 1995 .

[31]  IRAS FSC 15307+3252: Gravitationally Lensed Seyfert or Cannibal Elliptical at Z = 0.93? , 1996, astro-ph/9605114.

[32]  D. M. Alexander,et al.  A Chandra observation of the z= 2.285 galaxy FSC 10214+4724: evidence for a Compton-thick quasar? , 2004, astro-ph/0411289.

[33]  M. S. Oey,et al.  Atlas of quasar energy distributions , 1994 .

[34]  C. Crawford,et al.  ROSAT HRI observations of IRAS P09104+4109: a massive cooling flow , 1995, astro-ph/9505052.

[35]  M. Rieke,et al.  Spectroscopic Redshifts to z > 2 for Optically Obscured Sources Discovered with the Spitzer Space Telescope , 2005, astro-ph/0502216.

[36]  Measuring the black hole masses of high-redshift quasars , 2002, astro-ph/0204473.

[37]  Silvia Mateos,et al.  The unresolved hard X-ray background: the missing source population implied by the Chandra and XMM-Newton deep fields , 2005 .

[38]  Simon J. E. Radford,et al.  Near-Infrared Spectroscopy and a Search for CO Emission in Three Extremely Luminous IRAS Sources: IRAS F09105+4108, IRAS F15307+3252, and PG 1634+706 , 1998, astro-ph/9806091.

[39]  On the lack of cold dust in IRAS P09104+4109 and IRAS F15307+3252: their spectral energy distributions and implications for finding dusty AGNs at high redshift , 2001, astro-ph/0104157.

[40]  George Chartas,et al.  Extreme X-Ray Behavior of the Low-Luminosity Active Nucleus in NGC 4395 , 2001, astro-ph/0502109.

[41]  Paul S. Smith,et al.  The Misdirected Central Engine of the Hyperluminous Infrared Galaxy and Type 2 QSO IRAS P09104+4109 , 1999 .