Constraining Black Hole Spin based on the Absence of Lense-Thirring Precession of Megamaser Clumps

TL;DR

This study uses the absence of Lense-Thirring precession in megamaser clumps to set upper limits on black hole spins in seven galaxies, providing insights into black hole properties through observational constraints.

Contribution

It introduces a novel method to constrain black hole spins by analyzing the lack of observed precession in megamaser emissions, linking geometric stability to spin limits.

Findings

Upper limits on black hole spins in seven galaxies.

Precession timescales exceed megamaser ages, constraining spin amplitudes.

Method provides a new observational approach to black hole spin estimation.

Abstract

We make use of the absence of Lense-Thirring precession of the innermost megamaser clumps around black holes in order to place upper limits on the spin amplitude of seven black holes at the center of megamaser galaxies: NGC 4258, NGC 2273, UGC 3789, NGC 3393, NGC 5495, NGC 5765b, and UGC 6093. The constraints are derived by requiring that the associated precession time-scale be longer than the age of the megamaser clumps, in order to preserve the single-plane geometry of the megamasers.