Red Quasars: Selecting Candidates in SDSS DR16 and Estimating Their Physical Parameters

TL;DR

This study identifies 733 red quasar candidates from SDSS DR16 using color cuts and estimates their SMBH parameters, revealing insights into their spin distributions and growth mechanisms.

Contribution

The paper introduces a method to select red quasar candidates and estimates their SMBH properties using three theoretical models, highlighting their spin characteristics and growth processes.

Findings

Large percentage of objects with retrograde spins, suggesting youth or merger origins.

Strong correlation between SMBH spin and mass, indicating disk accretion as a primary growth mechanism.

Red quasars likely include Seyferts and NLS1, with SMBH growth driven mainly by accretion.

Abstract

Using ''color cut'' method we obtained from SDSS DR16 catalog 733 red quasar candidates which amounted to approximately 4% of the objects from the initial sample. Then we estimated the radiative efficiency, spins, inclination angles, and corresponding new SMBH masses for all 733 objects using three theoretical models. Obtained spin distributions contain a large percentage of objects with retrograde rotation. It may indicate that these are either very young objects or objects that formed as a result of mergers. The dependencies of the estimated spin values on SMBH masses show strong correlation with linear fit slope 0.9-1.0 which allows us to assume that red quasars are likely to contain both Seyferts and NLS1, and that the main mechanism of SMBH mass growth in these objects is disk accretion.