Determining the torus covering factors for a sample of type 1 AGN in the local Universe

Ezhikode, Savithri H.; Gandhi, P.; Done, Chris; Ward, M. J.; Dewangan, G. C.; Misra, Ranjeev; Philip, Ninan Sajeeth

doi:10.1093/mnras/stx2160

Cited by 41 publications

(40 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is consistent with the very weak covering factor of 0.06 for the putative torus, which is inferred from the ratio of the infrared to the bolometric luminosity of the source (Ezhikode et al 2017). Moreover, the torus covering factor measured for Mrk 110 is one of the lowest reported in the Ezhikode et al (2017) sample; this is also in agreement with the lack of Compton hump. The equivalent widths of the moderately broad Fe Kα line are EW b = 61 +23 −27 eV and EW b = 43 +22 −27 eV for 2019 and 2020, respectively.…”

Section: Main X-ray Spectral Components Of the 2019 And 2020 Xmm-newton And Nustar Observationssupporting

confidence: 88%

“…For the narrow core of the Fe Kα line, we measure a EW n 20 eV, which is in the lower range of the values found for type-1 AGN (∼30−200 eV; Liu & Wang 2010;Shu et al 2010;Fukazawa et al 2011;Ricci et al 2014). This is consistent with the very weak covering factor of 0.06 for the putative torus, which is inferred from the ratio of the infrared to the bolometric luminosity of the source (Ezhikode et al 2017). Moreover, the torus covering factor measured for Mrk 110 is one of the lowest reported in the Ezhikode et al (2017) sample; this is also in agreement with the lack of Compton hump.…”

Section: Main X-ray Spectral Components Of the 2019 And 2020 Xmm-newton And Nustar Observationssupporting

confidence: 82%

See 1 more Smart Citation

The first simultaneous X-ray broadband view of Mrk 110 with XMM-Newton and NuSTAR

Porquet

Reeves

Grosso

et al. 2021

A&A

View full text Add to dashboard Cite

Context. Soft and hard X-ray excesses, compared to the continuum power-law shape between ∼2−10 keV, are common features observed in the spectra of active galactic nuclei (AGN) and are associated with the accretion disc-corona system around the supermassive black hole. However, the dominant process at work is still highly debated and has been proposed to be either relativistic reflection or Comptonisation. Such an investigation can be problematic for AGN that have significant intrinsic absorption, either cold or warm, which can severely distort the observed continuum. Therefore, AGN with no (or very weak) intrinsic absorption along the line-of-sight, called bare AGN, are the best targets for directly probing disc-corona systems. Aims. We aim to characterise the main X-ray spectral physical components from the bright bare broad-line Seyfert 1 AGN Mrk 110, as well as the physical process(es) at work in its disc-corona system viewed almost face-on. Methods. We perform the X-ray broadband spectral analysis thanks to two simultaneous XMM-Newton and NuSTAR observations performed on November 16−17, 2019, and April 5−6, 2020. We also use a deep NuSTAR observation obtained in January 2017 for the spectral analysis above 3 keV. Results. The broadband X-ray spectra of Mrk 110 are characterised by the presence of a prominent and absorption-free smooth soft X-ray excess, moderately broad O VII and Fe Kα emission lines, and a lack of a strong Compton hump. The continuum above ∼3 keV is very similar at both epochs, while some variability (stronger when brighter) is present for the soft X-ray excess. A combination of soft and hard Comptonisation by a warm and hot corona, respectively, plus mildly relativistic disc reflection reproduce the broadband X-ray continuum very well. The inferred warm corona temperature, kTwarm ∼ 0.3 keV, is similar to the values found in other sub-Eddington AGN, whereas the hot corona temperature, kThot ∼ 21−31 keV (depending mainly on the assumed hot corona geometry), is found to be in the lower range of the values measured in AGN.

show abstract

Section: Main X-ray Spectral Components Of the 2019 And 2020 Xmm-newton And Nustar Observationssupporting

confidence: 88%

Section: Main X-ray Spectral Components Of the 2019 And 2020 Xmm-newton And Nustar Observationssupporting

confidence: 82%

The first simultaneous X-ray broadband view of Mrk 110 with XMM-Newton and NuSTAR

Porquet

Reeves

Grosso

et al. 2021

A&A

View full text Add to dashboard Cite

show abstract

“…Other physical drivers may contribuite to make the physical properties and the geometry of the system -and therefore the SED -different. In the case of the torus, both primary source properties -such as the accretion rate (Ricci et al 2017;Ezhikode et al 2017) or the luminosity (Maiolino et al 2007;Treister et al 2008;Lusso et al 2013), and composition of the torus clouds (Audibert et al 2017;Ramos Almeida et al 2011;Alonso-Herrero et al 2011) can change the shape of the IR emission. We do note again, however, that, as for this study has been designed, the effects produced by drivers other than orientation are "blended" within the EW[O iii] bins.…”

Section: Discussionmentioning

confidence: 99%

Orientation effects on the near-infrared broad-band emission of quasars

Bisogni

Lusso

Marconi

et al. 2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We recently proposed the equivalent width (EW) of the narrow [OIII]5007Å emission line as an orientation indicator for active galactic nuclei. We tested this method on about 12,300 optically selected broad line quasars from the SDSS 7th Data Release at redshift z < 0.8 and with full width at half-maximum values of broad emission lines (Hα, Hβ, and Mg ii) larger than 2000 km/s. We now examine their spectral energy distributions (SEDs) using broad band photometry from the near-infrared to the ultraviolet to look for variations in the overall shape as a function of the EW[OIII]. We find that quasars with low EW[OIII] values (close to face-on position) have flatter near-infrared SEDs with respect to sources with high EW[OIII] values (almost edgeon). Moreover, quasars with high EW[OIII] values show a factor of ∼2 lower emission in the UV to quasars with low EW[OIII] values. Our findings indicate that the torus is clumpy and, on average, co-axial with the accretion disc and broad line region, in agreement with the most recent theoretical models for the obscuring torus.

show abstract

“…Studies in the infrared band indicate that the torus covering factor may be a function of luminosity (e.g., Maiolino et al 2007, Treister et al 2008, Assef et al 2013, and may correlate with other measurable properties (e.g., presence of broad lines in optical spectra; Mateos et al 2016). It has been suggested that the covering factor depends on the Eddington ratio (e.g., Ezhikode et al 2017, Buchner & Bauer 2017, Ricci et al 2017b, and that its dependence on luminosity or the Eddington ratio changes with redshift (e.g., Aird et al 2015, Buchner et al 2015. AGN population studies in the X-ray band suggest that the fraction of obscured AGN drops as a function of luminosity (e.g., Sazonov & Revnivtsev 2004, Hasinger 2008, Burlon et al 2011, Vasudevan et al 2013.…”

Section: Introductionmentioning

confidence: 99%

New Spectral Model for Constraining Torus Covering Factors from Broadband X-Ray Spectra of Active Galactic Nuclei

Baloković

Brightman

Harrison

et al. 2018

ApJ

222

273

View full text Add to dashboard Cite

The basic unified model of active galactic nuclei (AGNs) invokes an anisotropic obscuring structure, usually referred to as a torus, to explain AGN obscuration as an angle-dependent effect. We present a new grid of X-ray spectral templates based on radiative transfer calculations in neutral gas in an approximately toroidal geometry, appropriate for CCD-resolution X-ray spectra (FWHM 130 eV). Fitting the templates to broadband X-ray spectra of AGNs provides constraints on two important geometrical parameters of the gas distribution around the supermassive black hole: the average column density and the covering factor. Compared to the currently available spectral templates, our model is more flexible, and capable of providing constraints on the main torus parameters in a wider range of AGNs. We demonstrate the application of this model using hard X-ray spectra from NuSTAR (3-79 keV) for four AGNs covering a variety of classifications: 3C 390.3, NGC 2110, IC 5063, and NGC 7582. This small set of examples was chosen to illustrate the range of possible torus configurations, from disk-like to sphere-like geometries with column densities below, as well as above, the Compton-thick threshold. This diversity of torus properties challenges the simple assumption of a standard geometrically and optically thick toroidal structure commonly invoked in the basic form of the unified model of AGNs. Finding broad consistency between our constraints and those from infrared modeling, we discuss how the approach from the X-ray band complements similar measurements of AGN structures at other wavelengths.

show abstract

Determining the torus covering factors for a sample of type 1 AGN in the local Universe

Cited by 41 publications

References 80 publications

The first simultaneous X-ray broadband view of Mrk 110 with XMM-Newton and NuSTAR

The first simultaneous X-ray broadband view of Mrk 110 with XMM-Newton and NuSTAR

Orientation effects on the near-infrared broad-band emission of quasars

New Spectral Model for Constraining Torus Covering Factors from Broadband X-Ray Spectra of Active Galactic Nuclei

Contact Info

Product

Resources

About