The nature of luminous X-ray sources with mid-infrared counterparts

Abstract

We investigate the luminous X-ray sources in the Lockman Hole (LH) and the Extended Groth Strip (EGS) detected at 24microns using MIPS and also with IRAC on board Spitzer. We assemble optical/infrared spectral energy distributions (SEDs) for 45 X-ray/24micron sources in the EGS and LH. Only about 1/4 of the hard X-ray/24micron sources show pure type 1 AGN SEDs. More than half of the X-ray/24micron sources have stellar-emission-dominated or obscured SEDs, similar to those of local type 2 AGN and spiral/starburst galaxies. One-third of the sources detected in hard X-rays do not have a 24micron counterpart. Two such sources in the LH have SEDs resembling those of S0/elliptical galaxies. The broad variety of SEDs in the optical-to-Spitzer bands of X-ray selected AGN means that AGN selected according to the behavior in the optical/infrared will have to be supplemented by other kinds of data (e.g., X-ray) to produce unbiased samples of AGN.

arXiv commentAccepted to the ApJS Spitzer Special Issue

References in corpus (20)

• The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
• The 2-10 keV luminosity as a Star Formation Rate indicator
• XMM-Newton observation of the Lockman Hole; I. The X-ray Data
• The 24 Micron Source Counts in Deep Spitzer Surveys
• Optical and Infrared Properties of the 2 Ms Chandra Deep Field-North X-ray Sources
• The Chandra Deep Survey of the Hubble Deep Field North Area. II. Results from the Caltech Faint Field Galaxy Redshift Survey Area
• The Nature of the Hard X-ray Background Sources: Optical, Near-infrared, Submillimeter, and Radio Properties
• XMM-Newton observation of the Lockman Hole II. Spectral analysis
• "Hidden" Seyfert 2 Galaxies and the X-ray Background
• The ROSAT Deep Survey: VI. X-ray sources and Optical identifications of the Ultra Deep Survey
• The AGN contribution to mid-infrared surveys
• SPITZER Observations of the SCUBA/VLA Sources in the Lockman Hole: Star Formation History of Infrared-Luminous Galaxies
• IRAC Imaging of Lockman Hole
• The Chandra Deep Field North Survey. XI. X-ray emission from luminous infrared starburst galaxies
• The Far-Infrared Spectral Energy Distributions of X-ray-selected Active Galaxies
• Identification of luminous infrared galaxies at 1<z<2.5
• The European Large Area ISO Survey V: a BeppoSAX hard X-ray survey of the S1 region
• ISO investigates the nature of extremely-red hard X-ray sources responsible for the X-ray background
• Galaxy Clustering Evolution in the UH8K Weak Lensing Fields
• Multiwavelength Properties of the X-ray Sources in the Groth-Westphal Strip Field

Cited by in corpus (30)

• The stellar mass assembly of galaxies from z=0 to z=4. Analysis of a sample selected in the rest-frame near-infrared with Spitzer
• Spitzer view on the evolution of star-forming galaxies from z=0 to z~3
• The Cosmic Evolution of Hard X-ray Selected Active Galactic Nuclei
• Dusty Infrared Galaxies: Sources of the Cosmic Infrared Background
• PAHs contribution to the infrared output energy of the Universe at z~2
• Infrared power-law galaxies in the Chandra Deep Field South: AGN and ULIRGs
• Chandra and Spitzer unveil heavily obscured quasars in the SWIRE/Chandra Survey
• Spitzer Power-law AGN Candidates in the Chandra Deep Field-North
• The strong transformation of spiral galaxies infalling into massive clusters at z~0.2
• UV-to-FIR analysis of Spitzer/IRAC sources in the Extended Groth Strip II: Photometric redshifts, Stellar masses and Star formation rates
• SPITZER Observations of the SCUBA/VLA Sources in the Lockman Hole: Star Formation History of Infrared-Luminous Galaxies
• Mid-infrared properties of X-ray sources in the Extended Groth Strip
• IRAC Imaging of Lockman Hole
• Complete Multiwavelength Characterization of Faint Chandra X-ray Sources Seen in the Spitzer Wide-Area IR Extragalactic (SWIRE) Survey
• Redshifts from Spitzer Spectra for Optically Faint, Radio Selected Infrared Sources
• Identification of luminous infrared galaxies at 1<z<2.5
• An Evolutionary Model For Submillimeter Galaxies
• Does the AGN Unified Model Evolve with Redshift? Utilizing the X-ray Background to Predict the Mid-Infrared Emission of AGN
• Obscured and unobscured AGN populations in a hard-X-ray selected sample of the XMDS survey
• AEGIS: Radio and Mid-Infrared Selection of Obscured AGN Candidates
• Can the unresolved X-ray background be explained by emission from the optically-detected faint galaxies of the GOODS project?
• Extremely Red Objects in The Lockman Hole
• Chandra and Spitzer observations of CDFS X-ray obscured QSOs
• The Environment on few Mpc scales of Infrared Luminous Galaxies at Redshifts z~1
• Probing nuclear activity versus star formation at z~0.8 using near-infrared multi-object spectroscopy
• Characterization of AGN and their hosts in the Extended Groth Strip: a multiwavelength analysis
• Properties and Expected Number Counts of Active Galactic Nuclei and their Hosts in the Far Infrared
• EROs found behind lensing clusters. II. Stellar populations and dust properties of optical dropout EROs and comparison with related objects
• EROs found behind lensing clusters: II.Empirical properties, classification, and SED modelling based on multi-wavelength observations
• The X-ray-Infrared/Submillimetre Connection and the Legacy Era of Cosmology