Mass, Spin, and Ultralight Boson Constraints from the Intermediate Mass Black Hole in the Tidal Disruption Event 3XMM J215022.4-055108

TL;DR

This study models the X-ray spectra of a tidal disruption event to measure an intermediate mass black hole's mass and spin, providing new constraints on ultralight bosons and offering the first spin measurement of such an object.

Contribution

It presents the first measurement of spin for an intermediate mass black hole using TDE spectra, constraining ultralight boson masses and advancing black hole physics.

Findings

Black hole mass constrained to less than 2.2×10^4 solar masses.

Black hole spin measured to be approximately 0.8.

Ultralight boson masses between 1.0×10^-15 and 1.0×10^-16 eV are ruled out.

Abstract

We simultaneously and successfully fit the multi-epoch X-ray spectra of the tidal disruption event (TDE) 3XMM J215022.4-055108 using a modified version of our relativistic slim disk model that now accounts for angular momentum losses from radiation. We explore the effects of different disk properties and of uncertainties in the spectral hardening factor fc and redshift z on the estimation of the black hole mass M and spin a. Across all choices of theoretical priors, we constrain M to less than 2.2e4 Ms at 1 sigma confidence. Assuming that the TDE host is a star cluster associated with the adjacent, brighter, barred lenticular galaxy at z=0.055, we constrain M and a to be (1.75+0.45-0.05)e4 Ms and 0.8+0.12-0.02, respectively, at 1 sigma confidence. The high, but sub-extremal, spin suggests that, if this intermediate mass black hole (IMBH) has grown significantly since formation, it has acquired its last e-fold in mass in a way incompatible with both the standard and chaotic limits of gas accretion. Ours is the first clear IMBH with a spin measurement. As such, this object represents a novel laboratory for astro-particle physics; its M and a place tight limits on the existence of ultralight bosons, ruling out those with masses 1.0e-15 to 1.0e-16 eV.