Dusty discs in active galactic nuclei

Efstathiou, A.; Rowan-Robinson, M.

doi:10.1093/mnras/273.3.649

Cited by 330 publications

(445 citation statements)

References 0 publications

Supporting

Mentioning

432

Contrasting

Unclassified

Order By: Relevance

“…The dusty torus absorbs the AGN radiation and, then, reprocesses it to emerge in the infrared (IR), peaking in the mid-IR (MIR; ∼5-30 µm), according to torus models (e.g. Pier & Krolik 1992;Efstathiou & Rowan-Robinson 1995;Schartmann et al 2005;Hönig et al 2006;Nenkova et al 2008a,b;Stalevski et al 2012;Siebenmorgen, Heymann, & Efstathiou 2015).…”

Section: Introductionmentioning

confidence: 99%

The nuclear and extended mid-infrared emission of Seyfert galaxies

García-Bernete¹,

Almeida²,

Acosta–Pulido³

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

We present subarcsecond resolution mid-infrared (MIR) images obtained with 8-10 m-class ground-based telescopes of a complete volume-limited (D L <40 Mpc) sample of 24 Seyfert galaxies selected from the Swift/BAT nine month catalog. We use those MIR images to study the nuclear and circumnuclear emission of the galaxies. Using different methods to classify the MIR morphologies on scales of ∼400 pc, we find that the majority of the galaxies (75-83%) are extended or possibly extended and 17-25% are point-like. This extended emission is compact and it has low surface brightness compared with the nuclear emission, and it represents, on average, ∼30% of the total MIR emission of the galaxies in the sample. We find that the galaxies whose circumnuclear MIR emission is dominated by star formation show more extended emission (650±700 pc) than AGN-dominated systems (300±100 pc). In general, the galaxies with point-like MIR morphologies are face-on or moderately inclined (b/a∼0.4-1.0), and we do not find significant differences between the morphologies of Sy1 and Sy2. We used the nuclear and circumnuclear fluxes to investigate their correlation with different AGN and SF activity indicators. We find that the nuclear MIR emission (the inner ∼70 pc) is strongly correlated with the X-ray emission (the harder the X-rays the better the correlation) and with the [O IV] λ25.89 µm emission line, indicating that it is AGN-dominated. We find the same results, although with more scatter, for the circumnuclear emission, which indicates that the AGN dominates the MIR emission in the inner ∼400 pc of the galaxies, with some contribution from star formation.

show abstract

Section: Introductionmentioning

confidence: 99%

The nuclear and extended mid-infrared emission of Seyfert galaxies

García-Bernete¹,

Almeida²,

Acosta–Pulido³

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

show abstract

“…Rowan-Robinson & Efstathiou (2009) have shown that the suite of starburst models of Efstathiou et al (2000) and AGN dust tori models of Efstathiou & Rowan-Robinson (1995) successfully explain the distribution of starbursts and AGN in the diagnostic diagram proposed by Spoon et al (2007), 9.7 µm silicate depth versus 6.2 µm PAH equivalent width (Fig 1). While there is aliasing of the models in this diagram, since different combinations of starburst and AGN dust torus models can predict the same point in the diagram, the model sequences do populate the distribution of observed points well.…”

Section: -D Axially Symmetric Radiative Transfer Models For Infrarmentioning

confidence: 77%

“…More recent axially symmetric models for protostars have been developed by Whitney et al (2003Whitney et al ( , 2004. Axially symmetric radiative transfer models for AGN dust tori were developed by Pier & Krolik (1992), Granato & Danese (1994), and Efstathiou & Rowan-Robinson (1995). The main issue addressed by these papers was why we do not see the 10 µm silicate feature strongly in emission from Type I QSOs.…”

Section: -D Axially Symmetric Radiative Transfer Models For Infrarmentioning

confidence: 99%

Panchromatic radiation from galaxies as a probe of galaxy formation and evolution

Rowan-Robinson

2011

Proc. IAU

View full text Add to dashboard Cite

Abstract. I review work on modelling the infrared and submillimetre SEDs of galaxies. The underlying physical assumptions are discussed and spherically symmetric, axisymmetric, and 3-dimensional radiative transfer codes are reviewed. Models for galaxies with Spitzer IRS data and for galaxies in the Herschel-Hermes survey are discussed. Searches for high redshift infrared and submillimetre galaxies, the star formation history, the evolution of dust extinction, and constraints from source-counts, are briefly discussed.Keywords. infrared galaxies, radiative transfer, star formation Early work on radiative transfer models for infrared sourcesDuring the 1960s and early 1970s very simplistic models began to be developed for infrared sources associated with circumstellar dust shells, HII regions and star-forming regions. These models assumed that the dust grain density n(r) and temperature T(r) have a power-law dependence on radius r and that the dust is optically thin. Scattering was neglected and so the emission was simply calculated as a sum of n(r)Q ν B ν (T (r)), integrated over r.The first complete solution of the spherically symmetric radiative transfer problem for an optically thick dust cloud was by Leung (1975). He used detailed grain properties and carried out a full solution of the moment equations, including anisotropic scattering. The grain temperature was solved for by assuming radiative balance. Yorke & Krugel (1977) modelled the dynamical evolution of an HII region, including the interaction between gas and dust. Radiative transfer was approximated by diffusion. These two papers marked a tremendous step forward in the quality of models for infrared sources. To take advantage of numerical techniques which had been used in modelling stellar atmospheres, Leung essentially assumed that the radiation field is isotropic through most of the cloud (the Eddington approximation).Rowan-Robinson (1980) carried out a numerical solution of the full radiative transfer equation. The intensity, I ν (θ, r), was calculated throughout the cloud using a grid of values in ν, r, θ. This showed that the Eddington approximation is a poor assumption throughout a dust cloud and revealed the phenomenon of sideways beaming of the radiation field at the inner edge of cloud. Viewed from a distance a dust cloud surrounding a star should show a ring of bright emission in the mid infrared, coming from the inner edge of the dust cloud. A second interesting phenomenon revealed by a full solution of the radiative transfer equation is that of back radiation onto the star. The dust cloud radiates at the star and so the net spectrum of emission emerging from the star is no longer a blackbody, but has absorption bands at the wavelengths of dust emission features (Rowan-Robinson 1982). Rowan-Robinson & Harris (1982 applied this code to all the bright circumstellar dust shells in the AFGL survey. 446at https://www.cambridge.org/core/terms. https://doi

show abstract

“…The ISO data also allow us to investigate the mid-IR "AGN" bump in quasars covering a range of redshift and luminosity. We plan to use these data to test and constrain current models of emission from a molecular torus (Pier & Krolik 1992, Efstathiou & Rowan-Robinson 1995.…”

Section: Discussionmentioning

confidence: 99%

ISO Observations of Quasars and Quasar Hosts

Wilkes

1997

ESO Astrophysics Symposia

View full text Add to dashboard Cite

Abstract. The Infrared Space Observatory (ISO), launched in November 1995, allows us to measure the far-infrared (far-IR) emission of quasars in greater detail and over a wider energy range than previously possible. In this paper, preliminary results in a study of the 5-200 µm continuum of quasars and active galaxies are presented. Comparison of the spectral energy distributions show that, if the far-IR emission from quasars is thermal emission from galaxian dust, the host galaxies of quasars must contain dust in quantities comparable to IR luminous galaxies rather than normal spiral galaxies. In the near-IR, the ISO data confirm an excess due to a warm 'AGN-related' dust component, possibly from the putative molecular torus. We report detection of the high-redshift quasar, 1202-0727, in the near-IR indicating that it is unusually IR-bright compared with low-redshift quasars.

show abstract

Dusty discs in active galactic nuclei

Cited by 330 publications

References 0 publications

The nuclear and extended mid-infrared emission of Seyfert galaxies

The nuclear and extended mid-infrared emission of Seyfert galaxies

Panchromatic radiation from galaxies as a probe of galaxy formation and evolution

ISO Observations of Quasars and Quasar Hosts

Contact Info

Product

Resources

About