A1 Refereed original research article in a scientific journal
An empirical relation to estimate host galaxy stellar light from AGN spectra
Authors: Jalan Priyanka, Rakshit Suvendu, Woo Jong-Jak, Kotilainen Jari, Stalin C.S.
Publisher: Oxford University Press
Publication year: 2023
Journal: Monthly Notices of the Royal Astronomical Society: Letters
Journal name in source: Monthly Notices of the Royal Astronomical Society: Letters
Volume: 521
Issue: 1
First page : L11
Last page: L16
DOI: https://doi.org/10.1093/mnrasl/slad014(external)
Web address : https://doi.org/10.1093/mnrasl/slad014(external)
Self-archived copy’s web address: https://arxiv.org/abs/2302.01948(external)
Measurement of black hole mass for low-z (z≤ 0.8) Active Galactic Nuclei (AGNs) is difficult due to the strong contribution from host galaxy stellar light necessitating detailed spectral decomposition to estimate the AGN luminosity. Here, we present an empirical relation to estimate host galaxy stellar luminosity from the optical spectra of AGNs at z ≤ 0.8. The spectral data were selected from the fourteenth data release of the Sloan Digital Sky Survey (SDSS-DR14) quasar catalogue having a signal-to-noise ratio at 5100 Å (SNR5100) >10 containing 11 415 quasars. The median total luminosity (log (Ltotal/[erg s−1])), stellar luminosity (log (Lstar/[erg s−1])), and AGN continuum luminosity ((log Lcont/[erg s−1])) in our sample are 44.52, 44.06, and 44.30, respectively. We fit the AGN power-law continuum, host galaxy, and iron blend contribution, simultaneously over the entire available spectrum. We found the host galaxy fraction to anticorrelate with continuum luminosity and can be well-represented by a polynomial function, which can be used to correct the stellar light contribution from AGN spectra. We also found anticorrelation between host galaxy fraction and iron strength, Eddington ratio, and redshift. The empirical relation gives comparable results of host-fraction with the image decomposition method.