2022ApJ...924...48P -
Astrophys. J., 924, 48-48 (2022/January-2)
Detection of a 100,000 M☉ black hole in M31's most massive globular cluster: a tidally stripped nucleus.
PECHETTI R., SETH A., KAMANN S., CALDWELL N., STRADER J., DEN BROK M., LUETZGENDORF N., NEUMAYER N. and VOGGEL K.
Abstract (from CDS):
We investigate the presence of a central black hole (BH) in B023-G078, M31's most massive globular cluster. We present high-resolution, adaptive-optics assisted, integral-field spectroscopic kinematics from Gemini/NIFS that show a strong rotation (∼20 km s–1) and a velocity dispersion rise toward the center (37 km s–1). We combine the kinematic data with a mass model based on a two-component fit to HST ACS/HRC data of the cluster to estimate the mass of a putative BH. Our dynamical modeling suggests a >3σ detection of a BH component of 9.1–2.8+2.6×104M☉ (1σ uncertainties). The inferred stellar mass of the cluster is 6.22–0.05+0.03×106M☉, consistent with previous estimates, thus the BH makes up 1.5% of its mass. We examine whether the observed kinematics are caused by a collection of stellar mass BHs by modeling an extended dark mass as a Plummer profile. The upper limit on the size scale of the extended mass is 0.56 pc (95% confidence), which does not rule out an extended mass. There is compelling evidence that B023-G078 is the tidally stripped nucleus of a galaxy with a stellar mass >109 M☉, including its high-mass, two-component luminosity profile, color, metallicity gradient, and spread in metallicity. Given the emerging evidence that the central BH occupation fraction of >109 M☉ galaxies is high, the most plausible interpretation of the kinematic data is that B023-G078 hosts a central BH. This makes it the strongest BH detection in a lower-mass (<107 M☉) stripped nucleus, and one of the few dynamically detected intermediate-mass BHs.
Abstract Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Andromeda galaxy - Globular star clusters - Intermediate-mass black holes - Stellar kinematics - Local Group
Simbad objects:
12
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