The M_•–σ_e relation for local type 1 AGNs and quasars

¹ Instituto de Física y Astronomía, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Valparaíso, Chile
² Department of Space, Earth and Environment, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
³ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People’s Republic of China
⁴ Department of Astronomy, School of Physics, Peking University, Beijing 100871, People’s Republic of China

^⋆ Corresponding author; juan.molinato@uv.cl

Received: 23 October 2023
Accepted: 11 September 2024

Abstract

We analyzed Multi Unit Spectroscopic Explorer observations of 42 local z ≲ 0.1 type 1 active galactic nucleus (AGN) host galaxies taken from the Palomar-Green quasar sample and the close AGN reference survey. Our goal was to study the relation between the black hole mass (M_•) and bulge stellar velocity dispersion (σ_e) for type 1 active galaxies. The sample spans black hole masses of 10^6.0 − 10^9.2 M_⊙, bolometric luminosities of 10^42.9 − 10^46.0 erg s⁻¹, and Eddington ratios of 0.006 − 1.2. We avoided AGN emission by extracting the spectra over annular apertures. We modeled the calcium triplet stellar features and measured stellar velocity dispersions of σ_* = 60 − 230 km s⁻¹ for the host galaxies. We find stellar velocity dispersion values in agreement with previous measurements for local (z ≲ 0.1) AGN host galaxies, but slightly lower compared with those reported for nearby X-ray-selected type 2 quasars. Using a novel annular aperture correction recipe to estimate σ_e from σ_* that considers the bulge morphology and observation beam-smearing, we estimate flux-weighted σ_e = 60 − 250 km s⁻¹. If we consider the bulge type when estimating M_•, we find no statistical difference between the distributions of AGN hosts and the inactive galaxies on the M_•–σ_e plane for M_• ≲ 10⁸ M_⊙. Conversely, if we do not consider the bulge type when computing M_•, we find that both distributions disagree. We find no correlation between the degree of offset from the M_•–σ_e relation and Eddington ratio for M_• ≲ 10⁸ M_⊙. The current statistics preclude firm conclusions from being drawn for the high-mass range. We argue these observations support notions that a significant fraction of the local type 1 AGNs and quasars have undermassive black holes compared with their host galaxy bulge properties.