The Intermediate Mass Black Hole in Omega Centauri: Constraints on Accretion from JWST

TL;DR

This study uses JWST observations to search for signs of an intermediate mass black hole in Omega Centauri, constraining its accretion activity and mass through non-detections in multi-wavelength data.

Contribution

First JWST-based analysis providing constraints on IMBH accretion and mass in Omega Centauri, refining previous limits and discussing implications of non-detection.

Findings

No SEDs consistent with accreting IMBH models were detected.

JWST limits are more restrictive than previous radio limits for IMBHs below 6000 solar masses.

Faint IMBH emission could be obscured by nearby stars or require deeper observations.

Abstract

We analyze JWST observations of the central region of the globular cluster $\omega$ Centauri (NGC 5139, $\omega$ Cen hereafter), around the position of the candidate IMBH inferred by \cite{haberle_fast-moving_2024} from the motion of fast-moving stars in multi-epoch HST observations. We performed PSF-fitting photometry for sources in NIRCam (F200W and F444W) and MIRI (F770W and F1500W) and constructed UV to IR SEDs for sources within the central region of the cluster by using HST photometry from oMEGACat \citep{haberle_omegacat_2024}. None of the SEDs of reliably measured sources within this region resembles the SEDs computed from models of \cite{pesce_toward_2021} for IMBHs accreting from intracluster medium at low rates. Our JWST limits place constraints on combinations of IMBH mass and accretion rate, either due to the amount of material available to be accreted, or due to the fraction of accreting matter that actually falls into the IMBH. Our non-detection then does not necessarily contradict the mass range of the IMBH inferred from the fast moving stars. We discuss these constraints in the context of the model of \cite{pesce_toward_2021}. We find that JWST limits are more restrictive than the existing radio limits for IMBH masses $\lesssim 6000 M_{\odot}$. It is also possible that the faint IMBH emission is dominated by the light of a nearby star. Tighter limits on accretion onto the candidate IMBH can be placed with deeper observations, a more precise localization of the IMBH, and better measurements of the local intracluster medium density and temperature at the center of the cluster.