Merlin Observations of the OH Maser Emission from IRC+10420

AbstractWe have detected maser emission from the 36.2 GHz (4−1 → 30E) methanol transition towards NGC 4945. This emission has been observed in two separate epochs and is approximately five orders of magnitude more luminous than typical emission from this transition within our Galaxy. NGC 4945 is only the fourth extragalactic source observed hosting class I methanol maser emission. Extragalactic class I methanol masers do not appear to be simply highly-luminous variants of their galactic counterparts and instead appear to trace large-scale regions where low-velocity shocks are present in molecular gas.

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An accreting < 105M⊙ black hole at the center of dwarf galaxy IC750

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320003488 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 376-376

Author(s):

Ingyin Zaw

Keyword(s):

Black Holes ◽

Black Hole ◽

Dwarf Galaxies ◽

Dwarf Galaxy ◽

Host Galaxy ◽

Scaling Relations ◽

Host Galaxies ◽

Seed Formation ◽

Maser Emission ◽

Water Masers

AbstractNuclear black holes in dwarf galaxies are important for understanding the low end of the supermassive black hole mass distribution and the black hole-host galaxy scaling relations. IC 750 is a rare system which hosts an AGN, found in ˜0.5% of dwarf galaxies, with circumnuclear 22 GHz water maser emission, found in ˜3–5% of Type 2 AGNs. Water masers, the only known tracer of warm, dense gas in the center parsec of AGNs resolvable in position and velocity, provide the most precise and accurate mass measurements of SMBHs outside the local group. We have mapped the maser emission in IC 750 and find that it traces a nearly edge-on warped disk, 0.2 pc in diameter. The central black hole has an upper limit mass of ˜1 × 105 M⊙ and a best fit mass of ˜8 × 104 M⊙, one to two orders of magnitude below what is expected from black hole-galaxy scaling relations. This has implications for models of black hole seed formation in the early universe, the growth of black holes, and their co-evolution with their host galaxies.

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Megamasers as probes of galaxy mass spectrum evolution

Symposium - International Astronomical Union ◽

10.1017/s0074180900239934 ◽

1991 ◽

Vol 147 ◽

pp. 440-440

Author(s):

V.K. Khersonskii ◽

N.V. Voshchinnikov

Keyword(s):

Mass Spectrum ◽

Spectral Line ◽

Emission Line ◽

Frequency Shift ◽

Empirical Relation ◽

Far Infrared ◽

Merging Galaxies ◽

Maser Emission ◽

The Galaxy ◽

Very High

OH megamasers having very high luminosities in the spectral line can be effectively used for the probing of the evolutionary properties of the galaxies in the earliest cosmological epochs. The frequency shift of the emission line uniqually determines the redshift z, which tells about the epoch of emission. One of the important cosmological problems is the investigation of the galaxy mass spectrum in the expanding Universe. There is the empirical relation between the OH and far-infrared luminosities of galaxies. Therefore, if in the earliest cosmological epochs, there were galaxies with sufficient powerful infrared excesses and containing molecular material, they can be detected using the observations of their OH maser emission. The interacting and merging galaxies can be considered as the best candidates for such objects.

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Millimetre wavelength methanol masers survey towards massive star forming regions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307013051 ◽

2007 ◽

Vol 3 (S242) ◽

pp. 234-235

Author(s):

T. Umemoto ◽

N. Mochizuki ◽

K. M. Shibata ◽

D.-G. Roh ◽

H.-S. Chung

Keyword(s):

Detection Rate ◽

Massive Star ◽

Molecular Line ◽

Maser Emission ◽

Star Forming ◽

Methanol Maser ◽

Physical Conditions ◽

Star Forming Regions ◽

Methanol Masers ◽

Maser Sources

AbstractWe present the results of a mm wavelength methanol maser survey towards massive star forming regions. We have carried out Class II methanol maser observations at 86.6 GHz, 86.9 GHz and 107.0 GHz, simultaneously, using the Nobeyama 45 m telescope. We selected 108 6.7 GHz methanol maser sources with declinations above −25 degrees and fluxes above 20 Jy. The detection limit of maser observations was ~3 Jy. Of the 93 sources surveyed so far, we detected methanol emission in 25 sources (27%) and “maser” emission in nine sources (10%), of which thre “maser” sources are new detections. The detection rate for maser emission is about half that of a survey of the southern sky (Caswell et al. 2000). There is a correlation between the maser flux of 107 GHz and 6.7 GHz/12 GHz emission, but no correlation with the “thermal” (non maser) emission. From results of other molecular line observations, we found that the sources with methanol emission show higher gas temperatures and twice the detection rate of SiO emission. This may suggest that dust evaporation and destruction by shock are responsible for the high abundance of methanol molecules, one of the required physical conditions for maser emission.

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Laboratory experiment to investigate astrophysical cyclotron-maser emission

2011 International Conference on Infrared, Millimeter, and Terahertz Waves ◽

10.1109/irmmw-thz.2011.6105121 ◽

2011 ◽

Author(s):

D. C. Speirs ◽

S. L. McConville ◽

K. Ronald ◽

K. M. Gillespie ◽

A. W. Cross

Keyword(s):

Laboratory Experiment ◽

Maser Emission ◽

Cyclotron Maser

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Main line maser emission in the OH ground state -doublet as a result of overlapping far infrared transitions

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/178.3.441 ◽

1977 ◽

Vol 178 (3) ◽

pp. 441-450 ◽

Cited By ~ 7

Author(s):

M. Pelling

Keyword(s):

Ground State ◽

Far Infrared ◽

Main Line ◽

Maser Emission ◽

Ground State Doublet

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Dense Molecular Gas and H2O Maser Emission in Galaxies

Journal of Astrophysics and Astronomy ◽

10.1007/s12036-014-9269-x ◽

2014 ◽

Vol 35 (3) ◽

pp. 509-511

Author(s):

F. Huang ◽

J. S. Zhang ◽

R. M. Li ◽

H. K. Li

Keyword(s):

Molecular Gas ◽

Maser Emission

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Class I methanol masers in the Galactic center

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314000416 ◽

2013 ◽

Vol 9 (S303) ◽

pp. 147-149

Author(s):

L. O. Sjouwerman ◽

Y. M. Pihlström

Keyword(s):

Galactic Center ◽

Class I ◽

Large Array ◽

Maser Emission ◽

Very Large Array ◽

Sagittarius A ◽

Current Location ◽

Theoretical Predictions ◽

Methanol Masers ◽

Sgr A

AbstractWe report on the detection of 36 and 44 GHz Class I methanol (CH3OH) maser emission in the Sagittarius A (Sgr A) complex with the Karl G. Jansky Very Large Array (VLA). These VLA observations show that the Sgr A complex harbors at least three different maser tracers of shocked regions in the radio regime. The 44 GHz masers correlate with the positions and velocities of previously detected 36 GHz CH3OH masers, but less with 1720 MHz OH masers. Our detections agree with theoretical predictions that the densities and temperatures conducive for 1720 MHz OH masers may also produce 36 and 44 GHz CH3OH maser emission. However, many 44 GHz masers do not overlap with 36 GHz methanol masers, suggesting that 44 GHz masers also arise in regions too hot and too dense for 36 GHz masers to form. This agrees with the non-detection of 1720 MHz OH masers in the same area, which are thought to be excited under even cooler and less dense conditions. We speculate that the geometry of the 36 GHz masers outlines the current location of a shock front.

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