THE NuSTAR EXTRAGALACTIC SURVEY: A FIRST SENSITIVE LOOK AT THE HIGH-ENERGY COSMIC X-RAY BACKGROUND POPULATION

We report on the first 10 identifications of sources serendipitously detected by the Nuclear Spectroscopic Telescope Array (NuSTAR) to provide the first sensitive census of the cosmic X-ray background source population at ≳10 keV. We find that these NuSTAR-detected sources are ≈100 times fainter than those previously detected at ≳10 keV and have a broad range in redshift and luminosity (z = 0.020-2.923 and L_(10-40 keV) ≈ 4 × 10^(41)-5 × 10^(45) erg s^(–1)); the median redshift and luminosity are z ≈ 0.7 and L_(10-40 keV) ≈ 3 × 10^(44) erg s^(–1), respectively. We characterize these sources on the basis of broad-band ≈0.5-32 keV spectroscopy, optical spectroscopy, and broad-band ultraviolet-to-mid-infrared spectral energy distribution analyses. We find that the dominant source population is quasars with L_(10-40 keV) > 10^(44) erg s^(–1), of which ≈50% are obscured with N_H ≳ 10^(22) cm^(–2). However, none of the 10 NuSTAR sources are Compton thick (N_H ≳ 10^(24) cm^(–2)) and we place a 90% confidence upper limit on the fraction of Compton-thick quasars (L_(10-40 keV) > 10^(44) erg s^(–1)) selected at ≳10 keV of ≾33% over the redshift range z = 0.5-1.1. We jointly fitted the rest-frame ≈10-40 keV data for all of the non-beamed sources with L_(10-40 keV) > 10^(43) erg s^(–1) to constrain the average strength of reflection; we find R < 1.4 for Γ = 1.8, broadly consistent with that found for local active galactic nuclei (AGNs) observed at ≳10 keV. We also constrain the host-galaxy masses and find a median stellar mass of ≈10^(11) M_☉, a factor ≈5 times higher than the median stellar mass of nearby high-energy selected AGNs, which may be at least partially driven by the order of magnitude higher X-ray luminosities of the NuSTAR sources. Within the low source-statistic limitations of our study, our results suggest that the overall properties of the NuSTAR sources are broadly similar to those of nearby high-energy selected AGNs but scaled up in luminosity and mass.

[1]  R. Terrier,et al.  THE FOURTH IBIS/ISGRI SOFT GAMMA-RAY SURVEY CATALOG , 2009, 0910.1704.

[2]  N. Gehrels,et al.  THE 60 MONTH ALL-SKY BURST ALERT TELESCOPE SURVEY OF ACTIVE GALACTIC NUCLEUS AND THE ANISOTROPY OF NEARBY AGNs , 2012 .

[3]  Robert Antonucci,et al.  Unified models for active galactic nuclei and quasars , 1993 .

[4]  Giancarlo Cusumano,et al.  A new measurement of the cosmic X-ray background , 2009 .

[5]  J. Baldwin,et al.  ERRATUM - CLASSIFICATION PARAMETERS FOR THE EMISSION-LINE SPECTRA OF EXTRAGALACTIC OBJECTS , 1981 .

[6]  N. Gehrels,et al.  HOST GALAXY PROPERTIES OF THE SWIFT BAT ULTRA HARD X-RAY SELECTED ACTIVE GALACTIC NUCLEUS , 2011, 1107.1237.

[7]  Ralf Bender,et al.  The Demography of massive dark objects in galaxy centers , 1997, astro-ph/9708072.

[8]  M. Watson,et al.  Searching for Compton-thick active galactic nuclei at z similar to 0.1 , 2010 .

[9]  S. Barthelmy,et al.  Swift BAT Survey of AGNs , 2007, 0711.4130.

[10]  C. Urry,et al.  On the spectral energy distributions of blazars , 1996 .

[11]  D. Elbaz,et al.  GOODS-Herschel: radio-excess signature of hidden AGN activity in distant star-forming galaxies , 2012, 1210.2521.

[12]  D. R. Ballantyne,et al.  Connecting Galaxy Evolution, Star Formation, and the Cosmic X-Ray Background , 2005, astro-ph/0509356.

[13]  D. M. Alexander,et al.  The Chandra Deep Field North Survey. XIV. X-Ray-detected Obscured AGNs and Starburst Galaxies in the Bright Submillimeter Source Population , 2003 .

[14]  W. N. B. randt,et al.  The Chandra Deep Field-north Survey. Xiv. X-ray Detected Obscured Agns and Starburst Galaxies in the Bright Submm Source Population , 2002 .

[15]  Guenther Hasinger,et al.  Absorption properties and evolution of active galactic nuclei , 2008 .

[16]  D. Schneider,et al.  THE CHANDRA DEEP FIELD-SOUTH SURVEY: 4 Ms SOURCE CATALOGS , 2011, 1105.5643.

[17]  N. Gehrels.  Confidence limits for small numbers of events in astrophysical data , 1986 .

[18]  Yunjin Kim,et al.  Nuclear Spectroscopic Telescope Array (NuSTAR) Mission , 2013, 2013 IEEE Aerospace Conference.

[19]  E. Bell,et al.  The Optical and Near-Infrared Properties of Galaxies. I. Luminosity and Stellar Mass Functions , 2003, astro-ph/0302543.

[20]  T. Courvoisier,et al.  The intrinsic emission of Seyfert galaxies observed with BeppoSAX/PDS - I. Comparison of the average spectra of the three classes of Seyfert galaxies , 2003, astro-ph/0303085.

[21]  Y. Ueda,et al.  The evolution of the Compton thick fraction and the nature of obscuration for AGN in the Chandra Deep Field South , 2012, 1203.1045.

[22]  C. Conselice,et al.  submitted to ApJ Preprint typeset using L ATEX style emulateapj v. 10/09/06 AEGIS: NEW EVIDENCE LINKING ACTIVE GALACTIC NUCLEI TO THE QUENCHING OF STAR FORMATION , 2022 .

[23]  M. Dopita,et al.  Giant Lyα Nebulae Associated with High-Redshift Radio Galaxies , 2003, astro-ph/0303637.

[24]  N. Menci,et al.  CHASING HIGHLY OBSCURED QSOs IN THE COSMOS FIELD , 2008, 0810.0720.

[25]  Integral ibis extragalactic survey: Active galactic nuclei selected at 20-100 keV , 2006 .

[26]  Louis Lyons,et al.  A practical guide to data analysis for physical science students: Contents , 1991 .

[27]  G. Fazio,et al.  The Infrared Array Camera (IRAC) for the Spitzer Space Telescope , 2004, astro-ph/0405616.

[28]  M. L. N. Ashby,et al.  The evolution of the hard X-ray luminosity function of AGN , 2009, 0910.1141.

[29]  Paolo Giommi,et al.  The Connection between X-Ray-- and Radio-selected BL Lacertae Objects , 1995 .

[30]  Carl J. Grillmair,et al.  THE FIRST HYPER-LUMINOUS INFRARED GALAXY DISCOVERED BY WISE , 2012, 1208.5517.

[31]  Ralf Bender,et al.  THE ASTROPHYSICAL JOURNAL Preprint typeset using L ATEX style emulateapj v. 10/09/06 THE M–σ AND M–L RELATIONS IN GALACTIC BULGES, AND DETERMINATIONS OF THEIR INTRINSIC SCATTER , 2008 .

[32]  D. M. Alexander,et al.  WEAK HARD X-RAY EMISSION FROM TWO BROAD ABSORPTION LINE QUASARS OBSERVED WITH NuSTAR: COMPTON-THICK ABSORPTION OR INTRINSIC X-RAY WEAKNESS? , 2013, 1306.3500.

[33]  A. Marconi,et al.  The Relation between Black Hole Mass, Bulge Mass, and Near-Infrared Luminosity , 2003, astro-ph/0304274.

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

[35]  A. Merloni,et al.  THREE-YEAR SWIFT–BAT SURVEY OF ACTIVE GALACTIC NUCLEI: RECONCILING THEORY AND OBSERVATIONS? , 2010, 1012.0302.

[36]  J. Trump,et al.  Identifying Luminous AGN in Deep Surveys: Revised IRAC Selection Criteria , 2012 .

[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]  Filippo Frontera,et al.  The Cosmic X-Ray Background and the Population of the Most Heavily Obscured AGNs , 2006, astro-ph/0611228.

[39]  Arjun Dey,et al.  Submitted to the Astrophysical Journal Letters Mid-Infrared Selection of Active Galaxies , 2004 .

[40]  S. Sazonov,et al.  Statistical properties of local active galactic nuclei inferred from the RXTE 3–20 keV all-sky survey , 2004 .

[41]  L. Winter,et al.  X-RAY SPECTRAL PROPERTIES OF THE BAT AGN SAMPLE , 2008, 0808.0461.

[42]  Louis Lyons,et al.  A practical guide to data analysis for physical science students: Random numbers , 1991 .

[43]  D. M. Alexander,et al.  Optical and Infrared Properties of the 2 Ms Chandra Deep Field North X-Ray Sources , 2003, astro-ph/0306212.

[44]  Ann Hornschemeier,et al.  THE 4 Ms CHANDRA DEEP FIELD-SOUTH NUMBER COUNTS APPORTIONED BY SOURCE CLASS: PERVASIVE ACTIVE GALACTIC NUCLEI AND THE ASCENT OF NORMAL GALAXIES , 2012, 1204.1977.

[45]  M. Markevitch,et al.  Absolute Measurement of the Unresolved Cosmic X-Ray Background in the 0.5-8 keV Band with Chandra , 2005, astro-ph/0512542.

[46]  C. Megan Urry,et al.  The Evolution of Obscuration in Active Galactic Nuclei , 2006 .

[47]  D. M. Alexander,et al.  The Chandra Deep Field North Survey. V. 1 Ms Source Catalogs , 2001, astro-ph/0108404.

[48]  Alison L. Coil,et al.  The DEIMOS spectrograph for the Keck II Telescope: integration and testing , 2003, SPIE Astronomical Telescopes + Instrumentation.

[49]  K. Schawinski,et al.  HEAVILY OBSCURED AGN IN STAR-FORMING GALAXIES AT z ≃ 2 , 2009, 0911.0003.

[50]  Nanbo Peng,et al.  SDSS QUASARS IN THE WISE PRELIMINARY DATA RELEASE AND QUASAR CANDIDATE SELECTION WITH OPTICAL/INFRARED COLORS , 2012, 1204.6197.

[51]  I. Hook,et al.  The Gemini–North Multi‐Object Spectrograph: Performance in Imaging, Long‐Slit, and Multi‐Object Spectroscopic Modes , 2004 .

[52]  D. Stern,et al.  Using the Bright Ultrahard XMM-Newton survey to define an IR selection of luminous AGN based on WISE colours , 2012, 1208.2530.

[53]  W. Cash,et al.  Parameter estimation in astronomy through application of the likelihood ratio. [satellite data analysis techniques , 1979 .

[54]  M. Watson,et al.  Searching for Compton-thick active galactic nuclei at z∼ 0.1 , 2010, 1009.4929.

[55]  John A. Nousek,et al.  Chi-squared and C statistic minimization for low count per bin data. [Sampling in X ray astronomy] , 1989 .

[56]  W. N. Brandt,et al.  DEEP EXTRAGALACTIC X-RAY SURVEYS , 2005 .

[57]  Jean-Luc Starck,et al.  Astronomical Data Analysis , 2007 .

[58]  N. Hambly,et al.  The SuperCOSMOS Sky Survey . Paper I : Introduction and Description , 2001 .

[59]  D. Swartz,et al.  A COMPLETE SAMPLE OF ULTRALUMINOUS X-RAY SOURCE HOST GALAXIES , 2011 .

[60]  J. Greiner,et al.  BAT X-Ray Survey. I. Methodology and X-Ray Identification , 2007, 0712.2885.

[61]  C. Papovich,et al.  The Host Galaxies and Black Holes of Typical z~0.5-1.4 AGNs , 2007, 0712.3121.

[62]  R. Della Ceca,et al.  The luminosity function and cosmological evolution of X-ray-selected BL lacertae objects , 1991 .

[63]  Anthony H. Gonzalez,et al.  LOW-RESOLUTION SPECTRAL TEMPLATES FOR ACTIVE GALACTIC NUCLEI AND GALAXIES FROM 0.03 TO 30 μm , 2010 .

[64]  D. Schneider,et al.  TRACKING DOWN THE SOURCE POPULATION RESPONSIBLE FOR THE UNRESOLVED COSMIC 6–8 keV BACKGROUND , 2012, 1209.0467.

[65]  J. Greiner,et al.  THE DEEP LOOK AT THE HARD X-RAY SKY: THE SWIFT–INTEGRAL X-RAY (SIX) SURVEY , 2012, 1208.0016.

[66]  R. Schild,et al.  The Einstein Observatory Extended Medium-Sensitivity Survey. I - X-ray data and analysis , 1990 .

[67]  Robert Rosner,et al.  A Wavelet-Based Algorithm for the Spatial Analysis of Poisson Data , 2001 .

[68]  Unifying models for X-ray selected and Radio selected BL Lac Objects , 1997, astro-ph/9704113.

[69]  J. Turner.  X‐ray spectra of a large sample of quasars with ASCA , 2000, astro-ph/0003080.

[70]  P. Capak,et al.  The Cosmic Evolution of Hard X-Ray-selected Active Galactic Nuclei , 2004, astro-ph/0410527.

[71]  P. Ciliegi,et al.  The HELLAS2XMM Survey. VII. The Hard X-Ray Luminosity Function of AGNs up to z = 4: More Absorbed AGNs at Low Luminosities and High Redshifts , 2005, astro-ph/0509081.

[72]  P. Giommi,et al.  The 26 year-long X-ray light curve and the X-ray spectrum of the BL Lacertae object 1E 1207.9+3945 in its brightest state , 2007, 0710.2464.

[73]  A. Zdziarski,et al.  Angle-dependent Compton reflection of X-rays and gamma-rays , 1995 .

[74]  D. Elbaz,et al.  The XMM deep survey in the CDF-S - IV. Compton-thick AGN candidates , 2013, 1303.5556.

[75]  T. Sakamoto,et al.  THE 22 MONTH SWIFT-BAT ALL-SKY HARD X-RAY SURVEY , 2009, 0903.3037.

[76]  C. Megan Urry,et al.  THE SPACE DENSITY OF COMPTON-THICK ACTIVE GALACTIC NUCLEUS AND THE X-RAY BACKGROUND , 2009, 0902.0608.

[77]  Donald E. Osterbrock,et al.  Spectral Classification of Emission-Line Galaxies , 1987 .

[78]  The XMM-Newton view of PG quasars - I. X-ray continuum and absorption , 2004, astro-ph/0411051.

[79]  L. Guzzo,et al.  The Cosmic Evolution Survey (COSMOS): Overview* , 2006, astro-ph/0612305.

[80]  I. Georgantopoulos,et al.  XMM-Newton and Chandra measurements of the AGN intrinsic absorption: dependence on luminosity and redshift , 2006 .

[81]  D. Elbaz,et al.  Reliable Identification of Compton-thick Quasars at z ≈ 2: Spitzer Mid-Infrared Spectroscopy of HDF-oMD49 , 2008, 0803.0636.

[82]  E. Wright,et al.  MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THE WIDE-FIELD INFRARED SURVEY EXPLORER. I. CHARACTERIZING WISE-SELECTED ACTIVE GALACTIC NUCLEI IN COSMOS , 2012, 1205.0811.

[83]  A. Penzias,et al.  A Measurement of excess antenna temperature at 4080-Mc/s , 1965 .

[84]  F. Özel,et al.  The relation between optical extinction and hydrogen column density in the Galaxy , 2009 .

[85]  Guenther Hasinger,et al.  The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era , 2007 .

[86]  E. al.,et al.  The Sloan Digital Sky Survey: Technical summary , 2000, astro-ph/0006396.

[87]  L. Miller,et al.  Low accretion rates at the AGN cosmic downsizing epoch , 2007, 0709.0786.

[88]  K. K. Madsen,et al.  LIFTING THE VEIL ON OBSCURED ACCRETION: ACTIVE GALACTIC NUCLEI NUMBER COUNTS AND SURVEY STRATEGIES FOR IMAGING HARD X-RAY MISSIONS , 2011, 1105.0965.

[89]  Y. Avni,et al.  Energy spectra of X-ray clusters of galaxies , 1976 .

[90]  Spain.,et al.  Spitzer Power-Law Active Galactic Nucleus Candidates in the Chandra Deep Field-North , 2007, astro-ph/0701698.

[91]  R. Maiolino,et al.  The relation between AGN hard X-ray emission and mid-infrared continuum from ISO spectra: Scatter and unification aspects , , 2004, astro-ph/0402082.

[92]  D. M. Alexander,et al.  COLOR–MAGNITUDE RELATIONS OF ACTIVE AND NON-ACTIVE GALAXIES IN THE CHANDRA DEEP FIELDS: HIGH-REDSHIFT CONSTRAINTS AND STELLAR-MASS SELECTION EFFECTS , 2010, 1007.1453.

[93]  R. J. Assef,et al.  CHARACTERIZING THE MID-INFRARED EXTRAGALACTIC SKY WITH WISE AND SDSS , 2012, 1209.2065.

[94]  Didier Barret,et al.  An intermediate-mass black hole of over 500 solar masses in the galaxy ESO 243-49 , 2009, Nature.

[95]  K. Nandra,et al.  GINGA observations of the X-ray spectra of Seyfert galaxies. , 1994 .

[96]  R. Davé,et al.  Extended Lyman Alpha Nebulae at z=2.3: An Extremely Rare and Strongly Clustered Population , 2008 .

[97]  Takamitsu Miyaji,et al.  Cosmological Evolution of the Hard X-Ray Active Galactic Nucleus Luminosity Function and the Origin of the Hard X-Ray Background , 2003, astro-ph/0308140.

[98]  M. Skrutskie,et al.  The Two Micron All Sky Survey (2MASS) , 2006 .

[99]  X. Barcons,et al.  XMM-Newton observations of the Lockman hole: X-ray source catalogue and number counts , 2007, 0711.4822.

[100]  I. McGreer,et al.  A COMPARISON OF X-RAY AND MID-INFRARED SELECTION OF OBSCURED ACTIVE GALACTIC NUCLEI , 2009, 0911.2448.

[101]  R. Maiolino,et al.  The Distribution of Absorbing Column Densities among Seyfert 2 Galaxies , 1999, astro-ph/9902377.

[102]  D. Eisenstein,et al.  Accepted in ApJ. Preprint typeset using L ATEX style emulateapj v. 10/09/06 EXTENDED Lyα NEBULAE AT z ≃ 2.3: AN EXTREMELY RARE AND STRONGLY CLUSTERED POPULATION? 1 , 2022 .

[103]  J. Trump,et al.  The bolometric output and host-galaxy properties of obscured AGN in the XMM-COSMOS survey , 2011, 1108.4925.

[104]  R. D’Abrusco,et al.  IDENTIFICATION OF THE INFRARED NON-THERMAL EMISSION IN BLAZARS , 2011, 1203.0304.

[105]  I. Smail,et al.  THE CHANDRA DEEP FIELD-SOUTH SURVEY: 4 Ms SOURCE CATALOGS , 2008, 0806.3968.

[106]  The XMM-Newton Wide-Field Survey in the COSMOS Field. I. Survey Description , 2006, astro-ph/0612311.

[107]  A. Szalay,et al.  The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission , 2004, astro-ph/0411302.

[108]  J. E. Pesce,et al.  The Hubble Space Telescope Survey of BL Lacertae Objects. II. Host Galaxies , 1999, astro-ph/9911109.

[109]  Blair D. Savage,et al.  Observed Properties of Interstellar Dust , 1979 .

[110]  D. M. Alexander,et al.  The Extended Chandra Deep Field-South Survey: Chandra Point-Source Catalogs , 2005, astro-ph/0506607.

[111]  I. M. Stewart,et al.  The XMM-Newton serendipitous survey. V. The Second XMM-Newton serendipitous source catalogue , 2008, 0807.1067.

[112]  R. J. Assef,et al.  Low-Resolution Spectral Templates for Galaxies from 0.2 to 10 μm , 2007, 0708.1513.

[113]  L. Kewley,et al.  The Chandra Deep Field-South: Optical Spectroscopy. I. , 2003, astro-ph/0312324.

[114]  W. Brandt,et al.  X-RAY PROPERTIES OF THE NORTHERN GALACTIC CAP SOURCES IN THE 58 MONTH SWIFT/BAT CATALOG , 2012, 1212.2957.

[115]  Martin G. Cohen,et al.  THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE): MISSION DESCRIPTION AND INITIAL ON-ORBIT PERFORMANCE , 2010, 1008.0031.

[116]  Fiona A. Harrison,et al.  The Serendipitous Extragalactic X-Ray Source Identification Program. I. Characteristics of the Hard X-Ray Sample , 2003 .

[117]  F. R. Harnden,et al.  Chandra Multiwavelength Project. I. First X-Ray Source Catalog , 2003, astro-ph/0308492.

[118]  Michael A. Nowak,et al.  CIAO: Chandra's data analysis system , 2006, SPIE Astronomical Telescopes + Instrumentation.

[119]  J. L. Donley,et al.  IDENTIFYING LUMINOUS ACTIVE GALACTIC NUCLEI IN DEEP SURVEYS: REVISED IRAC SELECTION CRITERIA , 2012, 1201.3899.

[120]  N. Masetti,et al.  The INTEGRAL/IBIS AGN catalogue - I. X-ray absorption properties versus optical classification , 2012, 1207.4882.

[121]  C. Megan Urry,et al.  The Evolution of Obscuration in AGN , 2006 .

[122]  Buell T. Jannuzi,et al.  MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THE WIDE-FIELD INFRARED SURVEY EXPLORER. II. PROPERTIES OF WISE-SELECTED ACTIVE GALACTIC NUCLEI IN THE NDWFS BOÖTES FIELD , 2012, 1209.6055.

[123]  Takeshi Miyaji,et al.  COSMOLOGICAL EVOLUTION OF THE HARD X-RAY AGN LUMINOSITY FUNCTION , 2004 .

[124]  M. Dadina.  Seyfert galaxies in the local Universe (z ≤ 0.1) : the average X-ray spectrum as seen by BeppoSAX , 2008, 0801.4338.

[125]  C. B. Markwardt,et al.  The Swift/BAT High-Latitude Survey: First Results , 2005, astro-ph/0509860.

[126]  Columbia,et al.  THE CHANDRA DEEP PROTOCLUSTER SURVEY: Lyα BLOBS ARE POWERED BY HEATING, NOT COOLING , 2009, 0904.0452.

[127]  A. Marconi,et al.  Dust in active nuclei. I. evidence for anomalous properties , 2000, astro-ph/0010009.

[128]  W. Brandt,et al.  Supermassive black-hole growth over cosmic time: Active galaxy demography, physics, and ecology from Chandra surveys , 2010, Proceedings of the National Academy of Sciences.

[129]  A. Georgakakis,et al.  Constraining the fraction of Compton-thick AGN in the universe by modelling the diffuse X-ray background spectrum , 2012, 1209.5398.

[130]  S. O. Physics,et al.  The SuperCOSMOS Sky Survey – I. Introduction and description , 2001, astro-ph/0108286.

[131]  D. M. Alexander,et al.  The Chandra Deep Field North Survey. XIII. 2 Ms Point-Source Catalogs , 2003, astro-ph/0304392.

[132]  Germany,et al.  INTEGRAL/IBIS all-sky survey in hard X-rays , 2007, astro-ph/0701836.

[133]  The INTEGRAL complete sample of type 1 AGN , 2009, 0906.2909.

[134]  E. Greisen,et al.  The NRAO VLA Sky Survey , 1996 .

[135]  REVISITING THE GAMMA-RAY SOURCE 2FGL J1823.8+4312 , 2013 .

[136]  Harland W. Epps,et al.  THE KECK LOW-RESOLUTION IMAGING SPECTROMETER , 1995 .

[137]  G. Hasinger,et al.  Luminosity-dependent evolution of soft X-ray selected AGN : New Chandra and XMM-Newton surveys , 2005, astro-ph/0506118.