Hot graphite dust and the infrared spectral energy distribution of active galactic nuclei
156 citations recorded by the source corpus.
We present a detailed investigation of the near-infrared to far-infrared (near-IR to far-IR) spectral energy distribution (SED) of a large sample of Spitzer-observed active galactic nuclei (AGNs). We fitted the spectra of 51 narrow-line Seyfert 1 galaxies (NLS1s) and 64 broad-line Seyfert 1 galaxies (BLS1s) using a three-component model: a clumpy torus, a dusty narrow-line region and hot pure-graphite dust located in the outer part of the broad-line region (BLR). The fitting was performed on star formation (SF) subtracted SEDs using SF templates that take into account the entire range of possible host galaxy properties. We find that the mid-IR intrinsic emission of NLS1s and BLS1s is very similar, regardless of the AGN luminosity, with long-wavelength downturn at around 20–25 μm. We present a detailed model of the hot-dust component that takes into account the distribution of dust temperature within the clouds and their emission-line spectrum. The hot-dust continuum provides a very good fit to the observed near-IR continuum spectrum. Most line emission in this component is dramatically suppressed, except Mg ii λ2798 and He i lines that are still contributing significantly to the total BLR spectrum. We calculate the covering factors (CFs) of all the AGN components and show that the CF of the hot-dust clouds is about 0.15–0.35, similar to the CF of the torus, and is anticorrelated with the source luminosity and the normalized accretion rate.
Subfields: Astronomy and Astrophysics, Instrumentation
View Paper: https://www.semanticscholar.org/paper/983c307e345dd88ededb23f2a31d97022c915369
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Citations in the corpus
- The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, background): “…using 5.8µm could be intrinsically different from the 12µm based correlation, in particular since the hot dust component dominates the MIR emission at 5.8µm in many type I AGN rather than the warm component (dominating at 12µm, if present; e.g., Edelson & Malkan 1986; Mor & Netzer 2012).”
- REVERBERATION MEASUREMENTS OF THE INNER RADIUS OF THE DUST TORUS IN 17 SEYFERT GALAXIES (2014, methodology): “Mor & Netzer (2012) introduced a gas cloud with hot pure-graphite grains to account for such excess emission and constructed an SED model consisting of a hot-dust cloud, a clumpy dust torus, and a dusty NLR to fit the infrared SED of type-1 AGNs.”
- The mean star formation rate of X-ray selected active galaxies and its evolution from z~2.5: results from PEP-Herschel (2012, background): “This may indicate that our adopted intrinsic AGN SEDs are too FIR-bright, as suggested by Mor & Netzer (2012).”
- Revisiting the Unified Model of Active Galactic Nuclei (2015, methodology): “Interestingly, their comparison with sources that show no indication of mergers (Mor, Netzer & Elitzur 2009; Mor & Netzer 2012) shows very similar SEDs and a similar trend of decreasing covering factor with LAGN.”
- The dust covering factor in active galactic nuclei (2016, methodology): “Hence, rather than a well defined Rin determined by the sublimation radius, we expect to have a sublimation zone, from larger to smaller grains and from graphite to silicate (see e.g., Kishimoto et al. 2007; Mor & Netzer 2012).”
- DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARED EMISSION OF ACTIVE GALACTIC NUCLEI (2013, background): “Observational evidence strongly suggest that large graphite grains dominate this hot sublimation zone (e.g. Kishimoto et al. 2007, 2009b; Mor et al. 2009; Kishimoto et al. 2011a; Mor & Netzer 2012).”