TY - JOUR
T1 - Accessing Intermediate-mass Black Holes in 728 Globular Star Clusters in NGC 4472
AU - Wrobel, J. M.
AU - Maccarone, T. J.
AU - Miller-Jones, J. C.A.
AU - Nyland, K. E.
N1 - Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.
PY - 2021/9/1
Y1 - 2021/9/1
N2 - Intermediate-mass black holes (IMBHs) by definition have masses of MIMBH ∼ 102-5 Mo˙, a range with few observational constraints. Finding IMBHs in globular star clusters (GCs) would validate a formation channel for massive black-hole seeds in the early universe. Here, we simulate a 60 hr observation with the next-generation Very Large Array (ngVLA) of 728 GC candidates in the Virgo Cluster galaxy NGC 4472. Interpreting the radio detection thresholds as signatures of accretion onto IMBHs, we benchmark IMBH mass thresholds in three scenarios and find the following: (1) radio analogs of ESO 243-49 HLX-1, a strong IMBH candidate with {M}_{\mathrm{IMBH}} {\mathrm{HLX}}\sim {10} {4-5}\,\,{M}_{\odot } in a star cluster, are easy to access in all 728 GC candidates. (2) For the 30 GC candidates with extant X-ray detections, the empirical fundamental-plane relation involving black-hole mass plus X-ray and radio luminosities suggests access to {M}_{\mathrm{IMBH}}^{\mathrm{FP}}\sim {10}^{1.7-3.6}\,\,{M}_{\odot }, with an uncertainty of 0.44 dex. (3) A fiducial Bondi accretion model was applied to all 728 GC candidates and to radio stacks of the GC candidates. This model suggests access to IMBH masses, with a statistical uncertainty of 0.39 dex, of {M}_{\mathrm{IMBH}}^{{\rm{B}}}\sim {10}^{4.9-5.1}\,{M}_{\odot } for individual GC candidates, and {M}_{\mathrm{IMBH}}^{{\rm{B}},\mathrm{stack}}\sim {10}^{4.5}\,{M}_{\odot } for radio stacks of about 100-200 GC candidates. The fiducial Bondi model offers initial guidance, but is subject to additional systematic uncertainties and should be superseded by hydrodynamical simulations of gas flows in GCs.
AB - Intermediate-mass black holes (IMBHs) by definition have masses of MIMBH ∼ 102-5 Mo˙, a range with few observational constraints. Finding IMBHs in globular star clusters (GCs) would validate a formation channel for massive black-hole seeds in the early universe. Here, we simulate a 60 hr observation with the next-generation Very Large Array (ngVLA) of 728 GC candidates in the Virgo Cluster galaxy NGC 4472. Interpreting the radio detection thresholds as signatures of accretion onto IMBHs, we benchmark IMBH mass thresholds in three scenarios and find the following: (1) radio analogs of ESO 243-49 HLX-1, a strong IMBH candidate with {M}_{\mathrm{IMBH}} {\mathrm{HLX}}\sim {10} {4-5}\,\,{M}_{\odot } in a star cluster, are easy to access in all 728 GC candidates. (2) For the 30 GC candidates with extant X-ray detections, the empirical fundamental-plane relation involving black-hole mass plus X-ray and radio luminosities suggests access to {M}_{\mathrm{IMBH}}^{\mathrm{FP}}\sim {10}^{1.7-3.6}\,\,{M}_{\odot }, with an uncertainty of 0.44 dex. (3) A fiducial Bondi accretion model was applied to all 728 GC candidates and to radio stacks of the GC candidates. This model suggests access to IMBH masses, with a statistical uncertainty of 0.39 dex, of {M}_{\mathrm{IMBH}}^{{\rm{B}}}\sim {10}^{4.9-5.1}\,{M}_{\odot } for individual GC candidates, and {M}_{\mathrm{IMBH}}^{{\rm{B}},\mathrm{stack}}\sim {10}^{4.5}\,{M}_{\odot } for radio stacks of about 100-200 GC candidates. The fiducial Bondi model offers initial guidance, but is subject to additional systematic uncertainties and should be superseded by hydrodynamical simulations of gas flows in GCs.
UR - http://www.scopus.com/inward/record.url?scp=85114792018&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/ac0ef3
DO - 10.3847/1538-4357/ac0ef3
M3 - Article
AN - SCOPUS:85114792018
SN - 0004-637X
VL - 918
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 18
ER -