Fundamental Planes, and the "barless" M-sigma relation, for supermassive black holes

TL;DR

This paper investigates the correlations between supermassive black hole masses and host galaxy properties, revealing that barred galaxies deviate from standard relations and that removing them yields tighter, more accurate scaling relations.

Contribution

It introduces a 'barless' M-sigma relation by excluding barred galaxies, resulting in reduced scatter and more reliable SMBH mass predictions compared to previous models.

Findings

Removing barred galaxies tightens the M-sigma relation.

The barless relation has an intrinsic scatter of 0.17 dex.

SMBH masses are generally less than 2-4 billion solar masses.

Abstract

The residuals about the standard M-sigma relation correlate with the effective radius, absolute magnitude, and Sersic index of the host bulge - although, it is noted here that the elliptical galaxies do not partake in such correlations. Moreover, it is revealed that barred galaxies (with their relatively small, faint, and low stellar concentration bulges) can deviate from the M-sigma relation by delta(log M) = -0.5 to -1.0 dex (in the sense that their sigma values are too large) and generate much of the aforementioned correlations. Removal of the seven barred galaxies from the Tremaine et al. set of 31 galaxies results in a ``barless M-sigma'' relation with an intrinsic scatter of 0.17 dex (cf. 0.27 dex for the 31 galaxies) and a total scatter of 0.25 dex (cf. 0.34 dex for the 31 galaxies). The introduction of third parameters does not reduce the scatter of the barless M-sigma relation. Furthermore, removal of the barred galaxies, or all the disk galaxies, from an expanded and updated set of 40 galaxies with reliable black hole mass measurements gives a consistent result, such that log(M_bh/M_sun) = (8.25+/-0.05) + (3.68+/-0.25)log [sigma/200]. The "barless" sigma-L relation for galaxies with black hole mass measurements is found to be consistent with that from the SDSS sample of early-type galaxies. In addition, the barless M-sigma relation, the M-L relation, and the M-n relation are all shown to yield SMBH masses less than 2-4 x 10^9 M_sun.