Resolving the mid-infrared cores of local Seyferts

By Poshak Gandhi, H. Horst, A. Smette, S. Hoenig, A. Comastri, R. Gilli, C. Vignali, Wolfgang J. Duschl. 2009

323 citations recorded by the source corpus.

We present new photometry of 16 local Seyferts including 6 Compton-thick sources in N -band filters around 12- μ m, obtained with the VISIR instrument on the 8-m Very Large Telescope. The near-diffraction-limited imaging provides the least-contaminated core fluxes for these sources to date. Augmenting these with our previous observations and with published intrinsic X-ray fluxes, we form a total sample of 42 sources for which we find a strong mid-infrared:X-ray (12.3  μ m:2–10 keV) luminosity correlation. Performing a physically-motivated subselection of sources in which the Seyfert torus is likely to be best-resolved results in the correlation L MIR  $\propto$ L X $^{1.11\pm 0.07}$, with a reduction of the scatter in luminosities as compared to the full sample. Consideration of systematics suggests a range of 1.02–1.21 for the correlation slope. The mean 2-keV:12.3- μ m spectral index ($\alpha_{\rm IX}$) is found to be -1.10$\;\pm\;$0.01, largely independent of luminosity. Indirectly-computed 12- μ m bolometric corrections range over ≈ 10–30 if a known luminosity trend of X-ray bolometric corrections is assumed. Comparison with ISO  data spanning a wider luminosity range suggests that our correlation can be extended into the quasar regime. That unobscured, obscured, and Compton-thick sources all closely follow the same luminosity correlation has important implications for the structures of Seyfert cores. The typical resolution-limit of our imaging corresponds to ~70 pc at a median $z=0.01$, and we use the tightness of the correlation to place constraints on the dominance of any residual emission sources within these physical scales. An upper-limit for any contaminating star formation of ≈ 40% of the unresolved flux is inferred, on average. We suggest that uncontaminated mid-IR continuum imaging of AGN is an accurate proxy for their intrinsic power.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/5525755e8dfc328e0352fb082ec6d9d697af6f13

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In Astronomy and Astrophysics

1. D. M. Alexander
2. P. Hopkins
3. L. Hernquist
4. W. N. Brandt
5. R. Hickox
6. E. Daddi
7. H. Netzer
8. D. Lutz

Citations in the corpus

• The mean star formation rate of X-ray selected active galaxies and its evolution from z~2.5: results from PEP-Herschel (2012, methodology): “The tight correlations betweenLX and 12.3µm IR luminosity among local AGNs (Gandhi et al. 2009) are used to link the bolometric AGN luminosity (derived fromLX) and the FIR luminosity (through the AGN IR SEDs).”
• What drives the growth of black holes (2011, background): “Using high-spatial mid-IR imaging (typically probing < 100 pc scales), Horst et al. (2008, 2009) 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 >…”
• IDENTIFICATION OF 1.4 MILLION ACTIVE GALACTIC NUCLEI IN THE MID-INFRARED USING WISE DATA (2015, background): “It is well established that the mid-IR luminosities of AGNs correlate strongly with their hard X-ray luminosities (Lutz et al. 2004; Gandhi et al. 2009; Mateos et al. 2015; Stern 2015, see also the relation in Secrest et al. 2015), as Compton up-scattering of UV photons from the accretion disk into…”
• Radiative efficiency, variability and Bondi accretion on to massive black holes: the transition from radio AGN to quasars in brightest cluster galaxies (2012, background): “Somewhat surprisingly, Gandhi et al. (2009) also found that the 8 Compton-thick sources in their sample did not deviate significantly from this rend.”
• Defining the intrinsic AGN infrared spectral energy distribution and measuring its contribution to the infrared output of composite galaxies (2011, methodology): “…output of composite galaxies, we use it to fit theIRASphotometry of two independent sample of galaxies; the sample of core-resolved Seyferts described in Horst et al. (2008) and Gandhi et al. (2009) and a subsample of the 12µm sample of Seyferts (e.g., Rush et al. 1993; Tommasin et al. 2010).”
• TESTING THE UNIFICATION MODEL FOR ACTIVE GALACTIC NUCLEI IN THE INFRARED: ARE THE OBSCURING TORI OF TYPE 1 AND 2 SEYFERTS DIFFERENT? (2011, unknown): “…Simpson (1998); (A7) Alonso-Herrero et al. (2001); (A8) Prieto et al. (2002); (A9) Carollo et al. (2002); (A10) Kulkarni et al. (1998); (A11) Ward et al. (1987); (B1) Horst et al. (2008); (B2) Prieto et al. (2010); (B3) Hönig et al. (2010); (B4) Gandhi et al. (2009); (B5) Haas et al. (2007) Note.”
• The incidence of obscuration in active galactic nuclei (2013, background): “5, is consistent with the expected ratio for a pure, unobscured AGN, based on the best-fitting relation of Gandhi et al. (2009) (solid vertical line).”
• BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog (2017, background): “V: X-ray properties of the Swift/BAT 70-month AGN catalog 21 (e.g., Lutz et al. 2004; Gandhi et al. 2009; Asmus et al. 2015; Stern 2015; Ichikawa et al. 2012, 2017), and has been interpreted as the signature of reprocessing of the accreting SMBH emission by dust in the torus.”
• IDENTIFYING LUMINOUS ACTIVE GALACTIC NUCLEI IN DEEP SURVEYS: REVISED IRAC SELECTION CRITERIA (2012, background): “However, no offset in MIR luminosity is observed when the AGN luminosity is instead normalized by the absorption-corrected X-ray luminosity and when the AGN’s contribution to the MIR emission is isolated either spatially or spectrally (Lutz et al. 2004; Gandhi et al. 2009).”
• Accreting supermassive black holes in the COSMOS field and the connection to their host galaxies (2012, background): “Using a sample of local Seyfert galaxies (both Seyfert 1 and Seyfert 2) at high spatial resolution, Gandhi et al. (2009) found that the uncontaminated nuclear MIR continuum of an AGN closely correlates with the X-ray [2–10] keV AGN emitted powers over three orders of magnitude in luminosity.”
• DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARED EMISSION OF ACTIVE GALACTIC NUCLEI (2013, background): “The actual degree of anisotropy in the mid-IR is still a matter of debate (e.g. Buchanan et al. 2006; Gandhi et al. 2009; Hönig et al. 2011; Asmus et al. 2011).”
• A diversity of dusty AGN tori - Data release for the VLTI/MIDI AGN Large Program and first results for 23 galaxies (2013, methodology): “…met our criteria from the literature available at the time of proposal writing (Krabbe et al., 2001; Siebenmorgen et al., 2004; Gorjian et al., 2004; Galliano et al., 2005; Haas et al., 2007; Raban et al., 2008; Horst et al., 2009; Gandhi et al., 2009; Prieto et al., 2010; Reunanen et al., 2010).”
• Active galactic nuclei: what’s in a name? (2017, background): “wavelengths) to assess the expected strength of the AGN and host-galaxy components at X-ray energies (e.g. Alexander et al. 2008; Gandhi et al. 2009; Georgantopoulos et al. 2011; Del Moro et al. 2013, 2016; Asmus et al. 2015) or utilis-”
• The active nuclei of z < 1.0 3CRR radio sources (2009, methodology): “The approximately linear correlation between mid-IR and X-ray power after correction for absorption is very similar to that found in lower-power objects (mostly radio-quiet Seyferts) by Gandhi et al. (2009) using 12.3 μm ground-based IR observations: above C© 2009 The Authors.”
• The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, methodology): “Out of these studies, the correlation parameters from Gandhi et al. (2009) are the most widely used because they apply to all classes of AGN including CT objects.”