Rotating Ionized Gas Ring around the Galactic Center IRS13E3. (arXiv:1907.12311v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tsuboi_M/0/1/0/all/0/1">Masato Tsuboi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kitamura_Y/0/1/0/all/0/1">Yoshimi Kitamura</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tsutsumi_T/0/1/0/all/0/1">Takahiro Tsutsumi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miyawaki_R/0/1/0/all/0/1">Ryosuke Miyawaki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miyoshi_M/0/1/0/all/0/1">Makoto Miyoshi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miyazaki_A/0/1/0/all/0/1">Atsushi Miyazaki</a>

We detected a compact ionized gas associated physically with IRS13E3, an
Intermediate Mass Black Hole (IMBH) candidate in the Galactic Center, in the
continuum emission at 232 GHz and H30$alpha$ recombination line using ALMA
Cy.5 observation (2017.1.00503.S, P.I. M.Tsuboi). The continuum emission image
shows that IRS13E3 is surrounded by an oval-like structure. The angular size is
$0″.093pm0″.006times 0″.061pm0″.004$ ( $1.14times10^{16}$ cm $times
0.74times10^{16}$ cm). The structure is also identified in the H30$alpha$
recombination line. This is seen as an inclined linear feature in the
position-velocity diagram, which is usually a defining characteristic of a
rotating gas ring around a large mass. The gas ring has a rotating velocity of
$V_mathrm{rot}simeq230$ km s$^{-1}$ and an orbit radius of
$rsimeq6times10^{15}$ cm. From these orbit parameters, the enclosed mass is
estimated to be $M_{mathrm{IMBH}}simeq2.4times10^4$ $M_odot$. The mass is
within the astrometric upper limit mass of the object adjacent to Sgr
A$^{ast}$. Considering IRS13E3 has an X-ray counterpart, the large enclosed
mass would be supporting evidence that IRS13E3 is an IMBH. Even if a dense
cluster corresponds to IRS13E3, the cluster would collapse into an IMBH within
$tau<10^7$ years due to the very high mass density of $rho gtrsim8times10^{11} M_odot pc^{-3}$. Because the orbital period is estimated to be as short as $T=2pi r/V_mathrm{rot}sim 50-100$ yr, the morphology of the observed ionized gas ring is expected to be changed in the next several decades. The mean electron temperature and density of the ionized gas are $bar{T}_{mathrm e}=6800pm700$ K and $bar{n}_{mathrm e}=6times10^5$ cm$^{-3}$, respectively. Then the mass of the ionized gas is estimated to be $M_{mathrm{gas}}=4times10^{-4} M_odot$.

We detected a compact ionized gas associated physically with IRS13E3, an
Intermediate Mass Black Hole (IMBH) candidate in the Galactic Center, in the
continuum emission at 232 GHz and H30$alpha$ recombination line using ALMA
Cy.5 observation (2017.1.00503.S, P.I. M.Tsuboi). The continuum emission image
shows that IRS13E3 is surrounded by an oval-like structure. The angular size is
$0″.093pm0″.006times 0″.061pm0″.004$ ( $1.14times10^{16}$ cm $times
0.74times10^{16}$ cm). The structure is also identified in the H30$alpha$
recombination line. This is seen as an inclined linear feature in the
position-velocity diagram, which is usually a defining characteristic of a
rotating gas ring around a large mass. The gas ring has a rotating velocity of
$V_mathrm{rot}simeq230$ km s$^{-1}$ and an orbit radius of
$rsimeq6times10^{15}$ cm. From these orbit parameters, the enclosed mass is
estimated to be $M_{mathrm{IMBH}}simeq2.4times10^4$ $M_odot$. The mass is
within the astrometric upper limit mass of the object adjacent to Sgr
A$^{ast}$. Considering IRS13E3 has an X-ray counterpart, the large enclosed
mass would be supporting evidence that IRS13E3 is an IMBH. Even if a dense
cluster corresponds to IRS13E3, the cluster would collapse into an IMBH within
$tau<10^7$ years due to the very high mass density of $rho
gtrsim8times10^{11} M_odot pc^{-3}$. Because the orbital period is estimated
to be as short as $T=2pi r/V_mathrm{rot}sim 50-100$ yr, the morphology of
the observed ionized gas ring is expected to be changed in the next several
decades. The mean electron temperature and density of the ionized gas are
$bar{T}_{mathrm e}=6800pm700$ K and $bar{n}_{mathrm e}=6times10^5$
cm$^{-3}$, respectively. Then the mass of the ionized gas is estimated to be
$M_{mathrm{gas}}=4times10^{-4} M_odot$.

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