The relation between AGN hard X-ray emission and mid-infrared continuum from ISO spectra: Scatter and unification aspects ,

By D. Lutz, R. Maiolino, H. Spoon, A. Moorwood. 2004

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We use mid-infrared spectral decomposition to separate the 6 μ m mid-infrared AGN continuum from the host emission in the ISO low resolution spectra of 71 active galaxies and compare the results to observed and intrinsic 2-10 keV hard X-ray fluxes from the literature. We find a correlation between mid-infrared luminosity and absorption corrected hard X-ray luminosity, but the scatter is about an order of magnitude, significantly larger than previously found with smaller statistics. Main contributors to this scatter are likely variations in the geometry of absorbing dust, and AGN variability in combination with non-simultaneous observations. There is no significant difference between type 1 and type 2 objects in the average ratio of mid-infrared and hard X-ray emission, a result which is not consistent with the most simple version of a unified scheme in which an optically and geometrically thick torus dominates the mid-infrared AGN continuum. Most probably, significant non-torus contributions to the AGN mid-IR continuum are masking the expected difference between the two types of AGN.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/54b4fc77a9c2749ea283d56948bbea391587e15a

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Spectral Energy Distributions of Hard X-Ray Selected Active Galactic Nuclei in the XMM-Newton Medium Deep Survey (2007, unknown): “Similarly to previous studies (Lutz et al. 2004; Horst et al. 2006; Sturm et al. 2006), we find that the mid-IR/X-ray luminosity ratio is characterized by a wide dispersion and does not depend on the AGN class or the X-ray luminosity.”
Swift BAT Survey of AGNs (2007, unknown): “(1) Swift XRT; (2) XTE/Akylas et al. 2002; (3) XMM/L. M. Winter et al. 2008a, in preparation; (4) Lutz et al. 2004; (5) Sambruna et al. 1998; (6) ASCA/R. F. Mushotzky et al. 2008, in preparation; (7) Gallo et al. 2006; (8) Tartarus database; (9) XMM/R. F. Mushotzky et al. 2008, in preparation; (10)…”
AGN Dusty Tori. II. Observational Implications of Clumpiness (2008, methodology): “The Lutz et al. (2004) finding was confirmed by Horst et al. (2006) who used the same approach with ground-based, and thus better resolution, observations at 12 m. Buchanan et al. (2006) conducted Spitzer observations of 87 Seyfert galaxies in the k ¼ 5Y35 m range and normalized the IR fluxes with…”
First X-ray-based statistical tests for clumpy-torus models: eclipse events from 230 years of monitoring of Seyfert AGN (2014, methodology): “Lutz et al. (2004) and Horst et al. (2006) demonstrated that the infrared (IR) emission by dust, which thermally re-radiates higher energy radiation, is isotropic, with type I and II Seyferts having similar ratios of X-ray to midIR luminosity.”
A UNIFIED EMPIRICAL MODEL FOR INFRARED GALAXY COUNTS BASED ON THE OBSERVED PHYSICAL EVOLUTION OF DISTANT GALAXIES (2012, methodology): “This scaling relation assumes a mean ratio between black hole and stellar mass of 0.0015 (Mullaney et al. 2012), plus a mean ratio betweenLAGNIR andL AGN bol calibrated from Mullaney et al. (2011), Lutz et al. (2004) and Vasudevan & Fabian (2007).”
An extreme [O III] emitter at z = 3.2: a low metallicity Lyman continuum source (2015, unknown): “The infrared and X-ray luminosities derived from the MIPS detection and the 6Ms upper limit, respectively, can be compared with the properties of known obscured AGN (Lanzuisi et al. 2015): Ion2 properties can be only consistent with a faint and highly obscured AGN (e.g., Lutz et al. 2004).”
A Multi-Transition HCN and HCO+ Study of 12 Nearby Active Galaxies: Active Galactic Nucleus versus Starburst Environments (2007, background): “Such correlations have not yet been found (e.g., Lutz et al. 2004; Gao & Solomon 2004a,b) but X-ray absorption in compton thick sources and variability effects might lead to a large scatter in the data used so far, thus washing out possible correlations.”
Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey (2017, methodology): “…luminosities for our sample are computed by fitting powerlaw slopes to the mid-IR photometry of the AGN, and using the best-fit slope to predict the rest-frame 6µm continuum luminosity, which is shown to be a robust indicator of LAGN (e.g., Lutz et al. 2004; Fiore et al. 2009; Chen et al. 2017).”
What drives the growth of black holes (2011, background): “…and Gandhi et al. (2009) found a tight correlation between the unresolved mid-IR core and the absorption-corrected X-ray luminosities of nearby AGNs, even in the presence of extreme Compton-thick (NH > 1024 cm−2) absorption (see Lutz et al. 2004 for similar constraints from mid-IR spectroscopy).”
Mid-Infrared Spectral Diagnosis of Submillimeter Galaxies (2007, background): “Mid-IR spectroscopy, by directly detecting the thermally reradiated emission from the obscuring dust, provides one of the most effective ways to identify AGNs, including Comptonthick sources, and measure their contribution to the IR luminosity (e.g., Lutz et al. 2004).”
The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, methodology): “While a strong MIR–X-ray correlation was reported in Elvis et al. (1978), Glass, Moorwood & Eichendorf (1982), Krabbe, Böker & Maiolino (2001) and Lutz et al. (2004), a fitting-based functional description of the correlation was only attempted in Horst et al. (2006, 2008) and Ramos Almeida et al.…”
Resolving the mid-infrared cores of local Seyferts (2009, methodology): “Resultii) above was also found in previous studies with lower-resolution ground and space observatories (e.g., Krabbe et al. 2001; Lutz et al. 2004), but was ascribed to the expected differences being mitigated due to the presence of unresolved contamination and other selection biases.”
Defining the intrinsic AGN infrared spectral energy distribution and measuring its contribution to the infrared output of composite galaxies (2011, background): “…would therefore provide a measure of the levels of AGN and star-formation activity that islargely unaffected by obscuration or absorption; similar, in principle, to the infrared spectral decompositions carried out by, for example, Laurent et al. (2000),Tran et al. (2001) and Lutz et al. (2004).”
Chandra and Spitzer Unveil Heavily Obscured Quasars in the Chandra/SWIRE Survey (2006, background): “Hard X-ray–mid-IR flux ratios in the local universe range from 10 3 for starburst galaxies to ’1 for unobscured AGNs (Alexander et al. 2001; Manners et al. 2004; Lutz et al. 2004).”
MID-INFRARED SPECTROSCOPY OF SUBMILLIMETER GALAXIES: EXTENDED STAR FORMATION IN MASSIVE HIGH-REDSHIFT GALAXIES (2009, background): “The mid-IR thus provides a complementary insight into a deeply obscured AGN (Sturm et al. 2006; Lutz et al. 2004).”
Revisiting the Unified Model of Active Galactic Nuclei (2015, unknown): “…12µm shows an almost identical mean ratio for the two AGN types, over four orders of magnitude in luminosity, with a typical scatter of about 0.3 dex (Lutz et al. 2004, Levenson et al. 2009, Gandhi 2009, Asmus et al. 2011, Hönig et al. 2010, Brightman & Nandra 2011b, González-Mart́ın et al.…”