Simulating intermediate black hole mass measurements for a sample of galaxies with nuclear star clusters using ELT/HARMONI high spatial resolution integral-field stellar kinematics

TL;DR

This study uses simulations to show that the upcoming ELT/HARMONI instrument can effectively measure intermediate-mass black holes in dwarf galaxy nuclei, advancing our understanding of black hole formation.

Contribution

The paper demonstrates, through realistic simulations, HARMONI's capability to detect and measure IMBHs in low-mass galaxies, a significant step forward in observational black hole research.

Findings

HARMONI can resolve IMBH spheres of influence in dwarf galaxies.

IMBH masses down to 0.5% of NSC mass can be accurately recovered.

Simulations suggest feasible observation times for IMBH detection.

Abstract

Understanding the demographics of intermediate-mass black holes (IMBHs, $M_{\rm BH} \approx 10^2-10^5$ M$_\odot$) in low-mass galaxies is key to constraining black hole seed formation models, but detecting them is challenging due to their small gravitational sphere of influence (SOI). The upcoming ELT/HARMONI instrument, with its high angular resolution, offers a promising solution. We present simulations assessing HARMONI's ability to measure IMBH masses in nuclear star clusters (NSCs) of nearby dwarf galaxies. We selected a sample of 44 candidates within 10 Mpc. For two representative targets, NGC 300 and NGC 3115 dw01, we generated mock HARMONI integral-field data cubes using realistic inputs derived from \hst\ imaging, stellar population models, and Jeans Anisotropic Models (JAM), assuming IMBH masses up to 1\% of the NSC mass. We simulated observations across six NIR gratings at 10 mas resolution. Analyzing the mock data with standard kinematic extraction (pPXF) and JAM models in a Bayesian framework, we demonstrate that HARMONI can resolve the IMBH SOI and accurately recover masses down to $\approx 0.5\%$ of the NSC mass within feasible exposure times. These results highlight HARMONI's potential to revolutionize IMBH studies.