scholarly journals Tidally-disrupted Molecular Clouds falling to the Galactic Center

2016 ◽  
Vol 11 (S322) ◽  
pp. 115-118 ◽  
Author(s):  
Masato Tsuboi ◽  
Yoshimi Kitamura ◽  
Kenta Uehara ◽  
Ryosuke Miyawaki ◽  
Atsushi Miyazaki
Keyword(s):  
Molecular Cloud ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Outer Region ◽  
Recombination Line ◽  
Ionized Gas ◽  
Boundary Area ◽  
Gas Streams ◽  
Uv Emission ◽  
Sgr A

AbstractWe found a molecular cloud connecting from the outer region to the “Galactic Center Mini-spiral (GCMS)” which is a bundle of the ionized gas streams adjacent to Sgr A*. The molecular cloud has a filamentary appearance which is prominent in the CSJ=2-1 emission line and is continuously connected with the GCMS. The velocity of the molecular cloud is also continuously connected with that of the ionized gas in the GCMS observed in the H42α recombination line. The morphological and kinematic relations suggest that the molecular cloud is falling from the outer region to the vicinity of Sgr A*, being disrupted by the tidal shear of Sgr A* and ionized by UV emission from the Central Cluster. We also found the SiOJ=2-1 emission in the boundary area between the filamentary molecular cloud and the GCMS. There seems to exist shocked gas in the boundary area.

scholarly journals How far actually is the Galactic Center IRS 13E3 from Sagittarius A*?

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Masato Tsuboi ◽  
Yoshimi Kitamura ◽  
Takahiro Tsutsumi ◽  
Ryosuke Miyawaki ◽  
Makoto Miyoshi ◽  
...  
Keyword(s):  
Galactic Center ◽  
Three Dimensional ◽  
Line Of Sight ◽  
Recombination Line ◽  
Intermediate Mass ◽  
Ionized Gas ◽  
Sagittarius A ◽  
Projection Distance ◽  
Spectroscopic Information ◽  
Sgr A

Abstract The Galactic Center IRS 13E cluster is a very intriguing infrared object located at ${\sim } 0.13$ pc from Sagittarius A$^\ast$ (Sgr A$^\ast$) in projection distance. There are arguments both for and against the hypothesis that a dark mass like an intermediate mass black hole (IMBH) exists in the cluster. We recently detected the rotating ionized gas ring around IRS 13E3, which belongs to the cluster, in the H30$\alpha$ recombination line using ALMA. The enclosed mass is derived to be $M_{\mathrm{encl.}}\simeq 2\times 10^{4}\, M_\odot$, which agrees with an IMBH and is barely less than the astrometric upper limit mass of an IMBH around Sgr A$^\ast$. Because the limit mass depends on the true three-dimensional (3D) distance from Sgr A$^\ast$, it is very important to determine it observationally. However, the 3D distance is indefinite because it is hard to determine the line-of-sight (LOS) distance by usual methods. We attempt here to estimate the LOS distance from spectroscopic information. The CH$_3$OH molecule is easily destroyed by the cosmic rays around Sgr A$^{\ast }$. However, we detected a highly excited CH$_3$OH emission line in the ionized gas stream associated with IRS 13E3. This indicates that IRS 13E3 is located at $r\gtrsim 0.4$ pc from Sgr A$^{\ast }$.

scholarly journals Rotating ionized gas ring around the Galactic center IRS13E3

2019 ◽  
Vol 71 (5) ◽  
Author(s):  
Masato Tsuboi ◽  
Yoshimi Kitamura ◽  
Takahiro Tsutsumi ◽  
Ryosuke Miyawaki ◽  
Makoto Miyoshi ◽  
...  
Keyword(s):  
Galactic Center ◽  
Mass Density ◽  
Angular Size ◽  
High Mass ◽  
Continuum Emission ◽  
Supporting Evidence ◽  
Recombination Line ◽  
Ionized Gas ◽  
Sgr A ◽  
The Continuum

Abstract 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 H30α 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${^{\prime\prime}_{.}}$093 ± 0${^{\prime\prime}_{.}}$006 × 0${^{\prime\prime}_{.}}$061 ± 0${^{\prime\prime}_{.}}$004 (1.14 × 1016 cm × 0.74 × 1016 cm). The structure is also identified in the H30α 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 Vrot ≃ 230 km s−1 and an orbit radius of r ≃ 6 × 1015 cm. From these orbit parameters, the enclosed mass is estimated to be $M_{\mathrm{IMBH}}\simeq 2.4\times 10^{4}\, M_{\odot }$. The mass is within the astrometric upper limit mass of the object adjacent to Sgr A*. 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 τ < 107 yr due to the very high mass density of $\rho \gtrsim 8\times 10^{11}\, M_{\odot }\:$pc−3. Because the orbital period is estimated to be as short as T = 2πr/Vrot ∼ 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 $\bar{T}_{\mathrm{e}}=6800\pm 700\:$K and $\bar{n}_{\mathrm{e}}=6\times 10^{5}\:$cm−3, respectively. Then the mass of the ionized gas is estimated to be $M_{\mathrm{gas}}=4\times 10^{-4}\, M_{\odot }$.

scholarly journals Unusually Wide, High-Velocity Radio Recombination Lines from G0.15–0.05 in the Radio Arc

1989 ◽  
Vol 136 ◽  
pp. 275-280 ◽  
Author(s):  
F. Yusef-Zadeh ◽  
Mark Morris ◽  
J. H. van Gorkom
Keyword(s):  
Radial Velocity ◽  
Galactic Center ◽  
Galactic Plane ◽  
Line Profiles ◽  
Recombination Line ◽  
Ionized Gas ◽  
Hii Region ◽  
Sgr A ◽  
Relativistic Particles ◽  
Kinematic Properties

The H92αrecombination line was observed at 8 GHz toward the “pistol-shaped” HII region G0.15–0.05 using the VLA2in its most compact configuration. The line profiles of individual components of this source peak at VLSR=123 km/s and have total line widths of ~90 km/s. The kinematical structure of the “pistol” is unusual in that much of the neutral and ionized gas in this region is seen predominantly at either +50 or +20 km/s. The line width and radial velocity are the largest found in the Galactic center region with the exception of Sgr A West. We also found gas at VLSR=140 km/s associated with G0.18–0.04: the sickle-shaped feature which surrounds G0.15–0.05. The kinematic properties of G0.18–0.04 and G0.15–0.05 suggest that these two features are components of a single, but complex thermal system interacting with the nonthermal filaments of the radio Arc. In this regard, the width of the broad recombination line from G0.15–0.05, and its large radial velocity, might be explained as the interaction of streaming relativistic particles in the nonthermal filaments of the Arc impacting upon ambient gas clouds lying in the Galactic plane.

scholarly journals Aperture Synthesis Obervations of The Galactic Center 50-km·s−1 Moleculer Could

1994 ◽  
Vol 140 ◽  
pp. 170-171
Author(s):  
Masato Tsuboi ◽  
Sachiko K. Okumura ◽  
Masato Ishiguro
Keyword(s):  
Molecular Cloud ◽  
Galactic Center ◽  
Galactic Plane ◽  
Recombination Line ◽  
Detailed Structure ◽  
Molecular Line ◽  
Star Forming ◽  
Star Forming Regions ◽  
Intimate Relation ◽  
Sgr A

Molecular clouds in the Galactic center region are distributed mainly along the Galactic plane and have filamentary shapes with several clumps (Bally et al. 1987, Tsuboi et al. 1989). The “50-km.s−1 molecular cloud (M-0.02-0.07)”, which is located ~3’ east from Sgr A West, is one of most remarkable clumps on these molecular filaments. The intimate relation between this cloud and Sgr A East has been mentioned by many authers (e.g. Ho et al. 1986). Several compact HII regions are located toward the cloud (Ekers et al. 1983). The recombination line velocities correspond to the molecular line velocities in the cloud (Goss et al. 1987). Thus this cloud is one of active star forming regions near the Galactic center.We observed the 50-km-s−1 molecular cloud in CS J=1-0 emission line (48.991 GHz) using the Nobeyama Millimeter Array (NMA) to reveal the detailed structure of the star forming regions near the Galactic center.

scholarly journals Molecular and ionized gas kinematics in the GC Radio Arc

2016 ◽  
Vol 11 (S322) ◽  
pp. 133-136
Author(s):  
N. Butterfield ◽  
C.C. Lang ◽  
E. A. C. Mills ◽  
D. Ludovici ◽  
J. Ott ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Radio Continuum ◽  
Molecular Gas ◽  
The South ◽  
Ionized Gas ◽  
Molecular Emission ◽  
Gas Kinematics

AbstractWe present NH3 and H64α+H63α VLA observations of the Radio Arc region, including the M0.20 – 0.033 and G0.10 – 0.08 molecular clouds. These observations suggest the two velocity components of M0.20 – 0.033 are physically connected in the south. Additional ATCA observations suggest this connection is due to an expanding shell in the molecular gas, with the centroid located near the Quintuplet cluster. The G0.10 – 0.08 molecular cloud has little radio continuum, strong molecular emission, and abundant CH3OH masers, similar to a nearby molecular cloud with no star formation: M0.25+0.01. These features detected in G0.10 – 0.08 suggest dense molecular gas with no signs of current star formation.

scholarly journals Probing Sagittarius A* accretion with ALMA

2016 ◽  
Vol 11 (S322) ◽  
pp. 21-24
Author(s):  
Elena Murchikova
Keyword(s):  
Galactic Center ◽  
Accretion Rate ◽  
Recombination Line ◽  
Ionized Gas ◽  
X Ray ◽  
Sagittarius A ◽  
Hydrogen Recombination ◽  
Unique Probe ◽  
Cool Gas

AbstractThe submm Hydrogen recombination line technique can be used as a probe of the Galactic Center. We present the results of our H30α observations of ionized gas from within 0.015 pc around SgrA*. The observations were obtained on ALMA in cycle 3. The line was not detected, but we were able to set a limit on the mass of the cool gas (T~ 104 K) at 2 × 10−3M⊙. This is the unique probe of gas cooler than T ~106 K traced by X-ray emission. The total amount of gas near SgrA* gives us clues to understanding the accretion rate of SgrA*.

scholarly journals A Survey of Radio Recombination Line Emission From the Galactic Center Region

1989 ◽  
Vol 136 ◽  
pp. 159-166 ◽  
Author(s):  
K. R. Anantharamaiah ◽  
Farhad Yusef-Zadeh
Keyword(s):  
Galactic Center ◽  
Line Emission ◽  
Radio Continuum ◽  
Strong Line ◽  
Line Profiles ◽  
Ionized Gas ◽  
Center Region ◽  
Radio Recombination Line ◽  
Nonthermal Emission ◽  
Sgr A

Preliminary results of a systematic survey of H78α, H91α and H98β emission from the inner 40′ of the Galactic center region are presented. This region consists of two prominent continuum features, the Sgr A complex and the radio continuum Arc. In spite of much nonthermal emission arising from these two features, we detected strong line emission with large line widths in more than half of the observed 130 positions. Many of the detections are new, in particular −50 km s−1 ionized gas linking the Sgr A complex and the Arc, β line emission from GO.1+0.08 (the arched filaments), and α line emission from the loop-like structures which surround the non-thermal filaments near G0.2−0.05. We find that much of the detected lines are probably associated with the −50 km s−1 and the 20 km s−1 molecular clouds, known to lie near the Galactic center. We present line profiles of a number of Galactic center sources including Sgr B1, Sgr C and Sgr D.

scholarly journals Oxygen isotope ratio studies in the Galactic center region

2013 ◽  
Vol 9 (S303) ◽  
pp. 123-125
Author(s):  
JiangShui Zhang ◽  
Lulu Sun ◽  
Jianjie Qiu ◽  
Dengrong Lu ◽  
Min Wang
Keyword(s):  
Oxygen Isotope ◽  
Intensity Ratio ◽  
Isotope Ratio ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Metal Enrichment ◽  
Oxygen Isotope Ratio ◽  
Integrated Intensity ◽  
Sgr A ◽  
Nuclear Processing

AbstractUsing the Delingha 13.7 m telescope with a 9-beam SIS superconducting receiver installed, we carried out mapping of C18O and C17O J = (1 − 0) toward molecular clouds in the central molecular zone (CMZ) and in the halo of our galaxy. From the integrated intensity ratio of C18O to C17O, the isotope ratio 18O/17O ratio can be estimated, which is considered to be one of the most useful tracers of nuclear processing and metal enrichment. Here preliminary results are presented toward Sgr A, Sgr B2, Sgr C, Sgr D, and the 1.°3 complex in the CMZ and M+5.3–0.3 in the halo.

scholarly journals Mini-spiral as source of material for Sgr A* in bright state

2012 ◽  
Vol 8 (S290) ◽  
pp. 199-200 ◽  
Author(s):  
Bozena Czerny ◽  
Vladimír Karas ◽  
Devaky Kunneriath ◽  
Tapas K. Das
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Supermassive Black Hole ◽  
The Past ◽  
Accretion Process ◽  
Ring Mode ◽  
Sgr A ◽  
Bright Phase

AbstractThe question of the origin of the gas supplying the accretion process is pertinent especially in the context of enhanced activity of Galactic Center during the past few hundred years, seen now as echo from the surrounding molecular clouds, and the currently observed new cloud approaching Sgr A*. We discuss the so-called Galactic Center mini-spiral as a possible source of material feeding the supermassive black hole on a 0.1 parsec scale. The collisions between individual clumps reduce their angular momentum. and set some of the clumps on a plunging trajectory.We conclude that the amount of material contained in the mini-spiral is sufficient to sustain the luminosity of Sgr A* at the required level. The accretion episodes of relatively dense gas from the mini-spiral passing through a transient ring mode at ~ 104 Rg provide a viable scenario for the bright phase of Galactic Center.

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