Detection of Ionized Gas toward an OH/IR Star: A Measure of the UV Radiation Field near the Galactic Center

1996 ◽  
Vol 458 (1) ◽  
Author(s):  
Farhad Yusef-Zadeh ◽  
Mark Wardle ◽  
Douglas Roberts
Keyword(s):  
Radiation Field ◽  
Uv Radiation ◽  
Galactic Center ◽  
Ionized Gas

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 Circumstellar Disks around Young Solar-type Stars

2004 ◽  
Vol 219 ◽  
pp. 385-389 ◽  
Author(s):  
Inga Kamp ◽  
Fatima Sammar
Keyword(s):  
Radiation Field ◽  
Uv Radiation ◽  
Circumstellar Disks ◽  
Central Star ◽  
Time Dependent ◽  
Solar Chromosphere ◽  
Starting Point ◽  
Solar Type ◽  
Time Dependent Behaviour ◽  
Dependent Behaviour

The chemistry of circumstellar disks around young (a few 10 Myr) solar-type stars is mainly driven by the strong UV radiation field of the central star. As a starting point for a detailed UV radiation field, the rocket and satellite observations of the solar chromosphere are used and scaled according to the time-dependent behaviour of stellar activity. The disk chemistry as well as dust and gas temperatures are then derived self-consistently from the model. The results of these calculations can be used for the identification of the most promising gas tracers as well as for the interpretation of present and future observations.

scholarly journals ISO-[CII]-Investigation of Cool HI Clouds in the Large Magellanic Cloud

1999 ◽  
Vol 190 ◽  
pp. 110-111
Author(s):  
M. Marx-Zimmer ◽  
F. Zimmer ◽  
U. Herbstmeier ◽  
J. M. Dickey
Keyword(s):  
Energy Balance ◽  
Radiation Field ◽  
Uv Radiation ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Heating And Cooling ◽  
First Results ◽  
Open Question

Despite a strong UV radiation field, the Large Magellanic Cloud (LMC) shows a relatively large abundance of cool HI gas. Neither CO- nor [CII]-lines have been detected in most of these regions in previous surveys. The energy balance of these cool clouds, of which some are located in warm surroundings, is still an open question. The improved resolution and sensitivity of the ISO telescope compared to previous measurements offers a unique opportunity to study the heating and cooling of these clouds in the LMC. Here we present first results of an investigation of the dominant cooling line, [CII] (158 μm), toward cool HI clouds.

scholarly journals Gas Feeding Toward the Central Neutral Ring in the Galactic Center

1989 ◽  
Vol 136 ◽  
pp. 379-382
Author(s):  
P. T. P. Ho ◽  
J. M. Jackson ◽  
J. T. Armstrong ◽  
J. C. Szczepanski
Keyword(s):  
Mass Distribution ◽  
Millimeter Wave ◽  
Gas Flow ◽  
Galactic Center ◽  
Ammonia Emission ◽  
Nuclear Region ◽  
Ionized Gas ◽  
Brightness Temperatures ◽  
Dominant Feature ◽  
Size Scales

VLA observations in the (J, K)=(3,3) line of ammonia reveal new structures in the Galactic center region. An approximate ring of emission is centered on the central ionized streamers. This ring, seen previously in millimeter-wave interferometer maps, is very clumpy in the ammonia emission, with size scales ≲10″ (0.4 pc). The clumps show good spatial and velocity agreement with the ionized gas, and are warm with brightness temperatures exceeding 30 K. A comparison of the (3,3) to (1,1) ratio indicates considerably higher gas temperatures. This circumnuclear ring may not be the dominant feature in the mass distribution of the circumnuclear gas. A streamer, immediately to the south of the Galactic center, connects the gas complex at lII= −4′ (~10 pc) directly to the Galactic center. This streamer may define the path for gas flow into the nuclear region.

scholarly journals 7.15. The Fourier analysis of the observed velocity field of gas in the inner 1.5 pc of the Galaxy

1998 ◽  
Vol 184 ◽  
pp. 321-324
Author(s):  
A.M. Fridman ◽  
V.V. Lyakhovich ◽  
O.V. Khoruzhii ◽  
O.K. Silchenko
Keyword(s):  
Velocity Field ◽  
Fourier Analysis ◽  
Galactic Center ◽  
Second Harmonic ◽  
Density Wave ◽  
Ionized Gas ◽  
Density Maximum ◽  
Fourier Harmonic ◽  
Wave Nature ◽  
The Galaxy

The Fourier analysis of the observed velocity field of ionized gas in the inner 1.5 pc of the Galactic Center (obtained by Roberts and Goss, 1993) is made. As follows from the analysis, the observed field of residual velocities is dominated by the second Fourier harmonic. This fact can be treated as a consequence of the presence of an one-armed density wave with the density maximum along the Northern Arm plus the Western Arc structure. The wave nature of this structure is proved on the base of the behaviour of the phase of the second harmonic of line-of-sight velocity field in the whole region. The Fourier analysis shows also the presence of systematic radial velocity. We consider this flow as a quasi-stationary radial drift caused by one-armed nonlinear density wave (‘mini-spiral’).

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 Observations of [OI]63 μm line emission in main-sequence galaxies at z ∼ 1.5

2020 ◽  
Vol 499 (2) ◽  
pp. 1788-1794
Author(s):  
J Wagg ◽  
M Aravena ◽  
D Brisbin ◽  
I Valtchanov ◽  
C Carilli ◽  
...  
Keyword(s):  
Field Strength ◽  
Interstellar Medium ◽  
Radiation Field ◽  
Uv Radiation ◽  
Main Sequence ◽  
Line Emission ◽  
The Other ◽  
Low Density ◽  
Star Forming ◽  
Neutral Gas

ABSTRACT We present Herschel–PACS spectroscopy of four main-sequence star-forming galaxies at z ∼ 1.5. We detect [OI]63 μm line emission in BzK-21000 at z = 1.5213, and measure a line luminosity, $L_{\rm [O\, {\small I}]63\, \mu m} = (3.9\pm 0.7)\times 10^9$ L⊙. Our PDR modelling of the interstellar medium in BzK-21000 suggests a UV radiation field strength, G ∼ 320G0, and gas density, n ∼ 1800 cm−3, consistent with previous LVG modelling of the molecular CO line excitation. The other three targets in our sample are individually undetected in these data, and we perform a spectral stacking analysis which yields a detection of their average emission and an [O i]63 μm line luminosity, $L_{\rm [O\, {\small I}]63\, \mu m} = (1.1\pm 0.2)\times 10^9$ L⊙. We find that the implied luminosity ratio, $L_{\rm [O\, {\small I}]63\, \mu m}/L_{\rm IR}$, of the undetected BzK-selected star-forming galaxies broadly agrees with that of low-redshift star-forming galaxies, while BzK-21000 has a similar ratio to that of a dusty star-forming galaxy at z ∼ 6. The high [O i]63 μm line luminosities observed in BzK-21000 and the z ∼ 1−3 dusty and sub-mm luminous star-forming galaxies may be associated with extended reservoirs of low density, cool neutral gas.

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 $M_{\mathrm{gas}}=4\times 10^{-4}\, M_{\odot }$.

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