Black hole masses of weak emission line quasars based on continuum fit method

TL;DR

This study estimates supermassive black hole masses in weak emission-line quasars using continuum fitting models based on accretion disk theory, revealing underestimations in previous methods and proposing a new mass estimation formula.

Contribution

It introduces a continuum fit method based on Novikov-Thorne models for estimating black hole masses in WLQs and establishes a new formula linking FWHM and luminosity for these objects.

Findings

Virial factor anti-correlates with FWHM of Hbeta.

Previous BH mass estimates are underestimated by a factor of 4-5.

Proposed a new formula for MBH estimation in WLQs.

Abstract

We studied optical-ultraviolet spectral energy distribution of 10 weak emission-line quasars (WLQs) which lie at redshifts z = 0.19 and 1.43 < z < 3.48. The theoretical models of their accretion disk continua are created based on the Novikov-Thorne equations. It allows us to estimate masses of their supermassive black holes (MBH) and accretion rates. We determined the virial factor for WLQs and note its anti-correlation with the full width at half maximum (FWHM) of Hbeta emission-line (f propto FWHM^(alpha), alpha = (-1.34 +/- 0.37)). By comparison with the previously estimated BH masses, the underestimation of MBH is noticed with a mean factor 4-5 which depends on the measured full width. We proposed the new formula to estimate MBH in WLQs based on their observed FWHM (H beta) and luminosities at 5100 A. In our opinion, WLQs are also normal quasars visible in a reactivation stage.