Study of central light concentration in nearby galaxies

TL;DR

This paper introduces a new photometric method using the central intensity ratio (CIR) to estimate supermassive black hole masses in nearby galaxies, linking galaxy structure to black hole evolution.

Contribution

It presents a novel, simple photometric technique based on CIR for estimating SMBH masses and distinguishing galaxy bulge types, enhancing galaxy evolution studies.

Findings

CIR correlates strongly with SMBH mass in ellipticals and classical bulges.

Pseudo bulges and mergers show scatter in CIR-SMBH relation.

CIR links with nuclear radio emission in low luminosity AGNs.

Abstract

We propose a novel technique to estimate the masses of super massive black holes (SMBHs) residing at the centres of massive galaxies in the nearby Universe using simple photometry. Aperture photometry using SEXTRACTOR is employed to determine the central intensity ratio (CIR) at the optical centre of the galaxy image for a sample of 49 nearby galaxies with SMBH mass estimations. We find that the CIR of ellipticals and classical bulges is strongly correlated with SMBH masses whereas pseudo bulges and ongoing mergers show significant scatter. Also, the CIR of low luminosity AGNs in the sample shows significant connection with the 5 GHz nuclear radio emission suggesting a stronger link between the former and the SMBH evolution in these galaxies. In addition, it is seen that various structural and dynamical properties of the SMBH host galaxies are correlated with the CIR making the latter an important parameter in galaxy evolution studies. Finally, we propose the CIR to be an efficient and simple tool not only to distinguish classical bulges from pseudo bulges but also to estimate the mass of the central SMBH.