The Fifth Candidate for an Intermediate-mass Black Hole in the Galactic Center. (arXiv:2002.05173v1 [astro-ph.GA])

The Fifth Candidate for an Intermediate-mass Black Hole in the Galactic Center. (arXiv:2002.05173v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Takekawa_S/0/1/0/all/0/1">Shunya Takekawa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Oka_T/0/1/0/all/0/1">Tomoharu Oka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Iwata_Y/0/1/0/all/0/1">Yuhei Iwata</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tsujimoto_S/0/1/0/all/0/1">Shiho Tsujimoto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nomura_M/0/1/0/all/0/1">Mariko Nomura</a>

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$^*$. 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.

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$^*$. 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.

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