# Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies

## TL;DR

This study characterizes the properties of the dusty torus in a volume-limited sample of Seyfert galaxies using high-resolution IR data and Bayesian modeling, revealing differences between types and potential biases in X-ray selection.

## Contribution

First characterization of torus properties in an ultra-hard X-ray selected Seyfert sample using high-res IR data and Bayesian models, highlighting differences between Seyfert types.

## Key findings

- Sy2s have larger torus covering factors than Sy1s.
- Torus covering factor is consistent across luminosities and Eddington ratios.
- X-ray selection may miss highly absorbed, high-covering-factor sources.

## Abstract

We characterize for the first time the torus properties of an ultra-hard X-ray (14-195 keV) volume-limited (DL<40 Mpc) sample of 24 Seyfert (Sy) galaxies (BCS40 sample). The sample was selected from the Swift/BAT nine month catalog. We use high angular resolution nuclear infrared (IR) photometry and N-band spectroscopy, the CLUMPY torus models and a Bayesian tool to characterize the properties of the nuclear dust. In the case of the Sy1s we estimate the accretion disk contribution to the subarcsecond resolution nuclear IR SEDs (~0.4'') which is, on average, 46+-28, 23+-13 and 11+-5% in the J-, H- and K-bands, respectively. This indicates that the accretion disk templates that assume a steep fall for longer wavelengths than 1 micron might underestimate its contribution to the near-IR emission. Using both optical (broad vs narrow lines) and X-ray (unabsorbed vs absorbed) classifications, we compare the global posterior distribution of the torus model parameters. We confirm that Sy2s have larger values of the torus covering factor (CT~0.95) than Sy1s (CT~0.65) in our volume-limited Seyfert sample. These findings are independent of whether we use an optical or X-ray classification. We find that the torus covering factor remains essentially constant within the errors in our luminosity range and there is no clear dependence with the Eddington ratio. Finally, we find tentative evidence that even an ultra hard X-ray selection is missing a significant fraction of highly absorbed type 2 sources with very high covering factor tori.