Defining the intrinsic AGN infrared spectral energy distribution and measuring its contribution to the infrared output of composite galaxies

By James Mullaney, D. M. Alexander, A. Goulding, R. Durham, U.K., CEA-Saclay, France., CfA-Harvard, U.S.. 2011

336 citations recorded by the source corpus.

ABSTRACT We use infrared spectroscopy and photometry to empirically define the intrinsic, thermal in-frared spectral energy distribution (i.e., 6-100µm SED) of typical active galactic nuclei (i.e.,2-10 keV luminosity,L 2−10keV ∼10 42 −10 44 ergs s −1 AGNs). On average, the infrared SED oftypical AGNs is best describedas a brokenpower-law at.40 µm that falls steeply at &40 µm(i.e., at far-infrared wavelengths). Despite this fall-off at long wavelengths, at least 3 of the 11AGNs in our sample have observed SEDs that are AGN-dominatedeven at 60 µm, demon-strating the importance of accounting for possible AGN contribution even at far-infraredwavelengths. Our results also suggest that the average intrinsic AGN 6-100µm SED getsbluer with increasing X-ray luminosity, a trend seen both within our sample and also when wecompare against the intrinsic SEDs of more luminous quasars (i.e., L 2−10keV &10 44 ergs s −1 ).We compare our intrinsic AGN SEDs with predictions from dusty torus models and find theyare more closely matched by clumpy, rather than continuous, torus models. Next, we use ourintrinsic AGN SEDs to define a set of correction factors to con vert either monochromatic in-frared or X-ray luminosities into total intrinsic AGN infrared (i.e., 8-1000µm) luminosities.Finally, we outline a procedure that uses our newly defined in trinsic AGN infrared SEDs, inconjunction with a selection of host-galaxy templates, to fit the infrared photometry of com-posite galaxies and measure the AGN contribution to their total infrared output. We verify theaccuracy of our SED fitting procedure by comparing our result s to two independent measuresof AGN contribution: (1) 12 µm luminosities obtained from high-spatial resolution observa-tions of nearby galaxies and (2) the equivalent width of the 11.25 µm PAH feature. Our SEDfitting procedureopens up the possibility of measuringthe i ntrinsic AGN luminosities of largenumbers of galaxies with well-sampled infrared data (e.g.,IRAS, ISO, Spitzer and Herschel).Key words: Galaxies, Seyfert, Active, Quasars, Infrared, X-rays

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/dbea0f943e7f7f6d2b24c04837b0576b13187d5a

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In Astronomy and Astrophysics

1. D. M. Alexander
2. P. Hopkins
3. L. Hernquist
4. E. Daddi
5. D. Elbaz
6. R. Dav'e
7. Mark Dickinson
8. P. V. van Dokkum

In Electrical and Electronic Engineering

1. S. Chapman
2. D. M. Alexander
3. S. Charlot
4. A. Koekemoer
5. R. Ivison
6. R. Maiolino
7. G. Cresci
8. W. N. Brandt

In Instrumentation

1. D. M. Alexander
2. E. Daddi
3. P. Hopkins
4. A. Renzini
5. Mark Dickinson
6. R. Dav'e
7. C. Conroy
8. L. Hernquist

Citations in the corpus

• BLACK HOLE VARIABILITY AND THE STAR FORMATION–ACTIVE GALACTIC NUCLEUS CONNECTION: DO ALL STAR-FORMING GALAXIES HOST AN ACTIVE GALACTIC NUCLEUS? (2013, background): “We note that this correlation is not due to contamination of the IR emission by the nucleus, as the AGN contribution at far-IR wavelengths is minimal (Netzer et al. 2007; Mullaney et al. 2011; Rosario et al. 2012).”
• Enhanced star formation rates in AGN hosts with respect to inactive galaxies from PEP-Herschel observations (2012, background): “However, the FIR continuum is shown to be dominated by the host galaxy emission for all but the most extreme AGN-dominated systems (Netzer et al. 2007; Lutz et al. 2008; Mullaney et al. 2011) and to be a proxy of its SF activity (Schweitzer et al. 2006; Lutz et al. 2008) (see also Sect.”
• Constraining the properties of AGN host galaxies with spectral energy distribution modelling (2015, methodology): “In this Section, we use our mock catalogues to test another method used to disentangle the AGN emission from the host galaxy in the IR, DecompIR4 (Mullaney et al. 2011).”
• Energetic galaxy-wide outflows in high-redshift ultraluminous infrared galaxies hosting AGN activity (2012, methodology): “Briefly, we fit the infrared data using the empirical AGN template defined in Mullaney et al. (2011), allowing for AV=0–5 mag of extinction, with each of the “SB2”–“SB5” starforming galaxy templates; the “SB1” star-formation template did not fit the data well in any of the sources.”
• The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, methodology): “On the other hand, NGC 4945 is Compton-thick obscured in X-rays exhibiting a highly variable and complex spectrum (e.g., c© 2015 RAS, MNRAS 000, 1–??”
• Panchromatic spectral energy distributions of Herschel sources (2013, neutral): “The full library comprises a total of roughly 700 models, each one computed at 10 different lines of sight anglesΦ, but we limit the fit toRout/Rin ≤ 100, as extreme values have so far not been confirmed by obser- vations (e.g. Mullaney et al. 2011; Hatziminaoglou et al. 2008; Netzer et al. 2007).”
• The mean star formation rate of X-ray selected active galaxies and its evolution from z~2.5: results from PEP-Herschel (2012, methodology): “For the SF templates, we consider the five basis SEDs from Mullaney et al. (2011) and add an M82like and Arp220-like SED from the SWIRE template library 2 available from http://sites.google.com/site/decompir/ (Polletta et al. 2007) to incorporate strongly star-bursting and ULIRG-like systems.”
• What drives the growth of black holes (2011, background): “…with redshift, in general agreement with the broad trend found for the overall galaxy population (e.g., Archibald et al., 2001; Serjeant & Hatziminaoglou, 2009; Mullaney et al., 2010, 2011b; Lutz et al., 2010; Shao et al., 2010; Xue et al., 2010; Mainieri et al., 2011; Seymour et al., 2011).”
• A CORRELATION BETWEEN STAR FORMATION RATE AND AVERAGE BLACK HOLE ACCRETION IN STAR-FORMING GALAXIES (2013, background): “However, it is also shown that AGNs have significant emission at near- to mid-IR wavelengths (e.g. Daddi et al. 2007; Mullaney et al. 2011), which poses challenges in obtaining reliable estimates of the SFR using mid-IR data.”
• PACS Evolutionary Probe (PEP) – a Herschel key program (2011, background): “This assumption is motivated by determinations of the intrinsic SED of the AGN proper, which is found to drop towards the far-infrared (e.g. Netzer et al. 2007, Mullaney et al. 2011).”
• EXPLAINING THE [C ii]157.7 μm DEFICIT IN LUMINOUS INFRARED GALAXIES—FIRST RESULTS FROM A HERSCHEL/PACS STUDY OF THE GOALS SAMPLE (2013, background): “This is most noticeable at mid-IR wavelengths (Laurent et al. 2000; Armus et al. 2007; Mullaney et al. 2011) but a non-negligible fraction of the far-IR emission of ULIRGs can also be powered by an AGN.”
• A remarkably flat relationship between the average star formation rate and AGN luminosity for distant X-ray AGN. (2015, methodology): “7 in Mullaney et al. 2011).”
• Erratum: Updating quasar bolometric luminosity corrections (2012, background): “…other recent investigations of quasar SEDs as well (Shang et al. 2011; Richards et al. 2006), those that focus on specific wavelength regimes (e.g., Mullaney et al. 2011; Nemmen & Brotherton 2010; Netzer et al. 2007; Vasudevan & Fabian 2007; Shang et al. 2005), those that focus on specific classes…”
• The Herschel view of the dominant mode of galaxy growth from z = 4 to the present day (2014, methodology): “In this procedure, photometric points below 30 μm rest-frame are not used in the fit since this is a domain that is potentially dominated by active galactic nuclei (AGN) torus emission, and not by star formation (e.g., Mullaney et al. 2011).”
• GOODS–Herschel: an infrared main sequence for star-forming galaxies (2011, background): “…is known that AGN can heat the dust that surrounds them to temperatures of several hundreds of Kelvin and produce a spectrum that can dominate the mid-IR emission of a galaxy, but which typically falls off steeply at wavelengths longer than 20µm (Netzer et al. 2007; see also Mullaney et al. 2011a).”
• Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population (2014, methodology): “3 We tested how much of an affect our limited range of templateshas on our quoted results (Table 2) by: (1) re-fitting including an Arp 220 model SED and (2) allowing the second power-law slope of the AGN model to be a free parameter (i.e.,α2 in Mullaney et al. 2011).”
• A TWO-PARAMETER MODEL FOR THE INFRARED/SUBMILLIMETER/RADIO SPECTRAL ENERGY DISTRIBUTIONS OF GALAXIES AND ACTIVE GALACTIC NUCLEI (2014, background): “…mid-infrared continuum datasets (e.g., Laurent et al. 2000; Murphy et al. 1Available at physics.uwyo.edu/∼ddale/research/seds/seds.html 7 2009; Mullaney et al. 2011; Wu et al. 2011) or a combination of the mid-infrared continnum plus mid-infrared fine-structure lines (e.g., Genzel et al.…”
• Revisiting the Unified Model of Active Galactic Nuclei (2015, background): “Indeed, a parallel effort by Mullaney et al. (2011) using a smaller sample of AGNs of both types, suggested a decline that starts at a longer wavelengths of about 30µm.”