Detection of faint broad emission lines in type 2 AGNs - III. On the MBH-sigma star relation of type 2 AGNs

Type 2 active galactic nuclei (AGNs) represent the majority of the AGN population. However, due to the difficulties in measuring their black hole (BH) masses, it is still unknown whether they follow the same BH mass–host galaxy scaling relations valid for quiescent galaxies and type 1 AGNs. Here, we present the locus of type 2 AGNs having virial BH mass estimates in the MBH-σ⋆ plane. Our analysis shows that the BH masses of type 2 AGNs are ∼0.9 dex smaller than type 1 AGNs at σ⋆ ∼ 185 km s‾¹, regardless of the (early/late) AGN host galaxy morphology. Equivalently, type 2 AGN host galaxies have stellar velocity dispersions ∼0.2 dex higher than type 1 AGN hosts at MBH ∼ 10⁷M⊙.Part of this work was supported by PRIN/MIUR 2010NHBSBE and PRIN/INAF 2014_3. We thank the referee for constructive comments that improved the quality of our Letter. We thank Cesare Perola for useful discussions. RS acknowledges support from the ERC Grant Agreement no. 306476. RM acknowledges ERC Advanced Grant 695671 ‘QUENCH’ and support by the Science and Technology Facilities Council (STFC). This Letter is based on observations made with ESO telescopes at the Paranal Observatory and the Large Binocular Telescope (LBT) at Mt Graham, Arizona. This research has made use of the HyperLeda data base and of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration