# Detection of faint broad emission lines in type 2 AGN: II. On the measurement of the BH mass of type 2 AGN and the unified model

## TL;DR

This study measures black hole masses in type 2 AGN using deep NIR spectroscopy and compares them with type 1 AGN, revealing significant differences that challenge the standard unification model of AGN.

## Contribution

It provides the first virial BH mass measurements for a sample of faint broad-line region components in type 2 AGN and compares these with type 1 AGN, questioning the unified model.

## Key findings

- Type 2 AGN have smaller BH masses than type 1 AGN at similar X-ray luminosities.
- Type 2 AGN BH masses range from 10^5 to 10^7.5 solar masses.
- Results suggest differences in BH mass distributions challenge the standard AGN unification model.

## Abstract

We report the virial measurements of the BH mass of a sample of 17 type 2 AGN, drawn from the Swift/BAT 70-month 14-195 keV hard X-ray catalogue, where a faint BLR component has been measured via deep NIR (0.8-2.5 $\mu$m) spectroscopy. We compared the type 2 AGN with a control sample of 33 type 1 AGN. We find that the type 2 AGN BH masses span the 5$<$ log(M$_{BH}$ /M$_{\odot}$) $< $7.5 range, with an average log(M$_{BH}$/M$_{\odot}$) = 6.7, which is $\sim$ 0.8 dex smaller than found for type 1 AGN. If type 1 and type 2 AGN of the same X-ray luminosity log($L_{14-195}$/erg s$^{-1}$) $\sim$ 43.5 are compared, type 2 AGN have 0.5 dex smaller BH masses than type 1 AGN. Although based on few tens of objects, this result disagrees with the standard AGN unification scenarios in which type 1 and type 2 AGN are the same objects observed along different viewing angles with respect to a toroidal absorbing material.