The Fifth Candidate for an Intermediate-mass Black Hole in the Galactic Center

Abstract

We report the results of high-resolution molecular line observations of the high-velocity compact cloud HCN-0.085-0.094 with the Atacama Large Millimeter/submillimeter Array. The HCN J=4-3, HCO${}^{+}$ J=4-3, and CS J=7-6 line images reveal that HCN-0.085-0.094 consists mainly of three small clumps with extremely broad velocity widths. Each of the three clumps has a 5.5 GHz radio continuum counterpart in its periphery toward Sgr A${}^{\ast }$. The positional relationship indicates that their surfaces have been ionized by ultraviolet photons from young stars in the central cluster, suggesting the clumps are in close proximity to the Galactic nucleus. One of the three clumps has a ring-like structure with a very steep velocity gradient. This kinematical structure suggests an orbit around a point-like object with a mass of $\sim 10^4$ $M_{\odot }$. The absence of stellar counterparts indicates that the point-like object may be a quiescent black hole. This discovery adds another intermediate-mass black hole candidate in the central region of our Galaxy.

8 pages, 4 figures, accepted for publication on the Astrophysical Journal

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Cited by in corpus (14)

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• Evidence for an intermediate-mass black hole from a gravitationally lensed gamma-ray burst
• The growth of intermediate mass black holes through tidal captures and tidal disruption events
• MOCCA-SURVEY Database II -- Properties of Intermediate Mass Black Holes escaping from star clusters
• Potential Black Hole Seeding of the Spiral Galaxy NGC 4424 via an Infalling Star Cluster
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• Astrophysics with the Laser Interferometer Space Antenna
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• Galactic Centre as an efficient source of cosmic rays
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• Discovery of the Tadpole Molecular Cloud near the Galactic Nucleus
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• Parabolic-like Trend in SiO Ratios throughout the Central Molecular Zone: Possible Signature of a Past Nuclear Activity in the Galactic Center