Type 1 AGN at low z

TL;DR

This study analyzes the emission properties of 3,579 low-redshift type 1 AGN, revealing consistent emission line widths, a scaled quasar SED, host galaxy relations, and correlations useful for identifying unobscured AGN.

Contribution

It provides a comprehensive characterization of low-z type 1 AGN emission features and host galaxy relations, with new insights into their spectral energy distributions and luminosity functions.

Findings

H-alpha FWHM distribution is luminosity-independent

Optical-UV SED matches scaled quasar templates with host contribution

Host galaxy luminosity function aligns with inactive galaxies

Abstract

We present the emission properties of a sample of 3,579 type 1 AGN, selected based on the detection of broad H-alpha emission. The sample covers the range of black hole mass 10^6<M_BH/M_Sun<10^9.5 and luminosity in Eddington units 10^-3 < L/L_Edd < 1. Our main results are: 1. The distribution of the H-alpha FWHM values is independent of luminosity. 2. The observed mean optical-UV SED is well matched by a fixed shape SED of luminous quasars, which scales linearly with broad H-alpha luminosity, and a host galaxy contribution. 3. The host galaxy r-band (fibre) luminosity function follows well the luminosity function of inactive non-emission line galaxies (NEG), consistent with a fixed fraction of ~3% of NEG hosting an AGN, regardless of the host luminosity. 4. The optical-UV SED of the more luminous AGN shows a small dispersion, consistent with dust reddening of a blue SED, as expected for thermal thin accretion disc emission. 5. There is a rather tight relation of nuL_nu(2 keV) and broad H-alpha luminosity, which provides a useful probe for unobscured (true) type 2 AGN.