UV-FIR SED modeling of AGN in IR-luminous galaxies up to z~2.5: Understanding the effects of torus models

Abstract

UV-FIR SED modeling is an effective way to disentangle emission between star formation (SF) and active galactic nuclei (AGN) in galaxies; however, this approach becomes uncertain for composite AGN/SF galaxies that comprise 50-70% of IR-samples. Cosmic X-ray background (XRB) models require a large fraction of obscured AGN to reproduce the observed XRB peak, motivating reliable SED analyses in objects where the AGN may be ``buried" in the galaxy and in the mid-IR to far-IR SED. In this paper, we study a 24$\mu$m-selected ($S_{24}$ > 100$\mu$Jy) sample of 95 galaxies with $0\%<f_{MIR,AGN}<100\%$, 0.4 < z < 2.7, and $10^{11}$L${}_{\odot }$ < L${}_{IR}$ < $10^{13}$L${}_{\odot }$. We test the performance of AGN models ranging in torus optical depth via SED fitting, comparing results with Spitzer MIR spectroscopy and X-ray observations. Best-fit torus optical depth can shed light on whether these galaxies host a luminous obscured AGN population. We find that permitting a broader AGN SED parameter space results in improved fit quality with higher optical depths, higher FIR AGN contributions, and higher $L_{Bol}$, impacting the bright-end of the $L_{Bol}$ luminosity function. Our results suggest there may be a population of dust-obscured composites that are bolometrically significant but have their AGN mostly hidden in the mid-IR SED. If so, literature applications of SED fitting that often simplify AGN models or omit optically thick tori may largely underestimate AGN contribution from composite sources, as these sources are both numerous and have solutions sensitive to the assumed range of AGN models.

20 pages, 10 figures

References in corpus (26)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• A simple model to interpret the ultraviolet, optical and infrared emission from galaxies
• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• AGN Dusty Tori: I. Handling of Clumpy Media
• The Chandra Deep Field-South Survey: 7 Ms Source Catalogs
• Mid-Infrared Spectral Diagnosis of Submillimeter Galaxies
• Multiwavelength study of massive galaxies at z~2. II. Widespread Compton thick AGN and the concurrent growth of black holes and bulges
• Constraining the properties of AGN host galaxies with Spectral Energy Distribution modeling
• The WISE AGN Catalog
• Growing supermassive black holes in the late stages of galaxy mergers are heavily obscured
• Optical spectroscopy and X-ray detections of a sample of quasars and AGN selected in the mid-infrared from two Spitzer wide-area surveys
• Spitzer's Contribution to the AGN Population
• Infrared Selection of Obscured Active Galactic Nuclei in the COSMOS Field
• Mass without radiation: heavily obscured AGN, the X-ray Background and the Black Hole Mass Density
• A Large Population of Obscured AGN in Disguise as Low Luminosity AGN in Chandra Deep Field South
• The AGN-Star Formation Connection: Future Prospects with JWST
• Linking the X-ray and infrared properties of star-forming galaxies at z<1.5
• Completing the Census of AGN in GOODS-S/HUDF: New Ultra-Deep Radio Imaging and Predictions for JWST
• The Past and Future of Mid-Infrared Studies of AGN
• Active Galactic Nuclei as seen by the Spitzer Space Telescope
• The Role of Star-Formation and AGN in Dust Heating of z=0.3-2.8 Galaxies - II. Informing IR AGN fraction estimates through simulations
• The AGN contribution to the UV-FIR luminosities of interacting galaxies and its role in identifying the Main Sequence
• [Ultra] Luminous Infrared Galaxies selected at 90 $\mu$m in the AKARI deep field: a study of AGN types contributing to their infrared emission
• AGN and star formation across cosmic time
• Where Do Obscured AGN Fit in A Galaxy's Timeline?

Cited by in corpus (5)

• Physical properties of hyperluminous, dust-obscured quasars at $z\sim 3$: multiwavelength Spectral Energy Distribution analysis and cold gas content revealed by ALMA
• Radio-only and Radio-to-far-ultraviolet Spectral Energy Distribution Modeling of 14 ULIRGs: Insights into the Global Properties of Infrared Bright Galaxies
• Exploring the physical properties of Type II Quasar candidates at intermediate redshifts with CIGALE
• Obscured and unobscured X-ray AGNs I: Host galaxy properties
• Cold Quasar Investigation: Comparing Star Formation Rates to Black Hole Growth