Megamaser galaxies

Kandalian, R. A.

doi:10.1007/bf02071997

Cited by 29 publications

(46 citation statements)

References 36 publications

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“…Our data, that of LDSL98 and Trotter et al (1997), and the results of Kandalyan (1996) suggest that although the classic megamaser model may explain the di †use OH emission it cannot explain the compact OH and continuum characteristics. The velocity gradients suggest that the compact OH is associated with massive objects in the nuclei of the galaxies.…”

Section: Discussionmentioning

confidence: 52%

“…However we have shown (this paper ; LDSL98) that the continuum emission is not coincident with the OH masers and that the masers are probably saturated. In addition, a reanalysis of the OH and FIR data for megamaser galaxies by Kandalyan (1996), which accounts for Malmquist bias, indicates that the OH and FIR relationship is more nearly linear than quadratic, with exponent 1.38^0.14. LDSL98 suggest that a model in which IR radiation is responsible for pumping (Henkel & Wilson 1990 ;Randell et al 1995 ;Skinner et al 1997) the compact OH masers is untenable and that collisional pumping in high-density environments (104 cm~3), such as expected for molecular tori, probably serves as the catalyst for maser action.…”

Section: Discussionmentioning

confidence: 99%

“…Pumping energy is supplied by the enormous IR luminosities evident in all OH megamaser galaxies. Support for this picture has come from an observed relation between the OH and far-infrared luminosity, (Baan L OH D L FIR 2 1989 ; Martin et al 1989 ; but see Kandalyan 1996 for a reanalysis). The broad (10 ] 100 km s~1) OH line widths are attributed to large-scale rotational motions in the ensemble of OH masing clouds (Staveley-Smith et al 1992).…”

Section: Introductionmentioning

confidence: 97%

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Global VLBI Observations of the Compact OH Megamaser Emission from III Zw 35 and IRAS 17208−0014

Diamond

Lonsdale

et al. 1999

ApJ

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We have performed global VLBI observations of the OH megamaser galaxies III Zw 35 and IRAS 17208[0014. We detect strong and compact 1667 MHz OH emission from each galaxy, but, apart from one weak detection of a single 1665 MHz OH feature in III Zw 35, no 1665, 1720 MHz, or continuum emission are detected, which indicates that they occur on size scales greater thanWe surmise that 0A .1. the OH emission consists of two components. One is di †use, has unsaturated masers pumped by farinfrared radiation, and is readily explained by the classical OH megamaser model. The second is compact, consists of saturated masers, is responsible for up to 65% of the 1667 MHz Ñux density, is not associated with any compact continuum emission, and may be pumped by a combination of collisional and radiative processes. One component in III Zw 35 exhibits a well-deÐned velocity gradient of 32^4 km s~1 pc~1 along a 5.5 pc line of masers. This indicates strong rotation of a molecular cloud with an enclosed mass density of D6 ] 104 pc~3. M _

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Section: Discussionmentioning

confidence: 52%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Global VLBI Observations of the Compact OH Megamaser Emission from III Zw 35 and IRAS 17208−0014

Diamond

Lonsdale

et al. 1999

ApJ

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“…The statistical analysis showed that the OHM luminosity was found to be increasing with the FIR luminosity of maser hosts as Martin et al 1988;Baan 1989;Kandalian 1996;Diamond et al 1999;Darling & Giovanelli 2002). In the MIR, Willett et al (2011b) combined both theory and Spitzer observation to explore the fundamental causes of OHM activity and found that OHMs prefer deeper 9.7 μm silicon absorption and warmer dust.…”

Section: Maser Emission and Mir Luminosities Of Ohm Hostsmentioning

confidence: 93%

“…Comparisons of multiband properties in detail between samples of OHM (U)LIRGs and non-OHM (U)LIRGs are, thus, important and helpful to answer above questions. Many related works have been done, and no significant difference could be found between OHM and non-OHM (U)LIRGs in the radio, optical, and X-ray regimes A&A 570, A110 (2014) (e.g., Lonsdale et al 1998;Baan et al 1998;Vignali et al 2005;Kandalian 1996;Darling & Giovanelli 2002). Since OHMs in (U)LIRGs were generally believed to be pumped by infrared radiation (e.g., Henkel & Wilson 1990;Randell et al 1995;Lockett & Elitzur 2008;Willett et al 2011b), more related studies thus focused on the infrared properties of OHM hosts, which is important for understanding the pumping mechanism of megamaser and its physical nature.…”

Section: Introductionmentioning

confidence: 99%

The middle infrared properties of OH megamaser host galaxies

Zhang

Wang

et al. 2014

A&A

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We compiled all 119 OH maser galaxies (110 out of them are megamasers, i.e., L OH > 10 L ) published so far and cross-identified these OH masers with the Wide-Field Infrared Survey Explorer (WISE) catalog, to investigate the middle infrared (MIR) properties of OH maser galaxies. The WISE magnitude data at the 3.4, 4.6, 12 and 22 μm (W1 to W4) are collected for the OH maser sample and one control sample, which are non-detection sources. The color-color diagrams show that both OH megamaser (OHM) and non-OHM (ultra)luminous infrared galaxies ((U)LIRGs) are far away from the single blackbody model line and many of them can follow the path described by the power-law model. The active galaxy nuclei (AGN) fraction is about ∼40% for both OHM and non-OHM (U)LIRGs, according to the AGN criteria W1−W2 ≥ 0.8. Among the Arecibo survey sample, OHM sources tend to have a lower luminosity at short MIR wavelengths (e.g., 3.4 μm and 4.6 μm) than that of non-OHM sources, which should come from the low OHM fraction among the survey sample with large 3.4 μm and 4.6 μm luminosity. The OHM fraction tends to increase with cooler MIR colors (larger F 22 μm /F 3.4 μm ). These may be good for sample selection when searching OH megamasers, such as excluding extreme luminous sources at short MIR wavelengths, choosing sources with cooler MIR colors. In the case of the power-law model, we derived the spectral indices for our samples. For the Arecibo survey sample, OHM (U)LIRGs tend to have larger spectral index α 22−12 than non-OHM sources, which agrees with previous results. One significant correlation exists between the WISE infrared luminosity at 22 μm and the color [W1]-[W4] for the Arecibo OHM hosts. These clues should provide suitable constraints on the sample selection for OH megamaser surveys by future advanced telescopes (e.g., FAST). In addition, the correlation of maser luminosity and the MIR luminosity of maser hosts tends to be non-significant, which may indirectly support the pumping of OHM emission that is dominated by the far infrared radiation, instead of the MIR radiation.

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Ultraluminous Infrared Galaxies

Lonsdale

Farrah

Smith

Springer Praxis Books

180

182

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Ever since their discovery in the 1970's, UltraLuminous InfraRed Galaxies (ULIRGs; classically Lir>10^12Lsun) have fascinated astronomers with their immense luminosities, and frustrated them due to their singularly opaque nature, almost in equal measure. Over the last decade, however, comprehensive observations from the X-ray through to the radio have produced a consensus picture of local ULIRGs, showing that they are mergers between gas rich galaxies, where the interaction triggers some combination of dust-enshrouded starburst and AGN activity, with the starburst usually dominating. Very recent results have thrown ULIRGs even further to the fore. Originally they were thought of as little more than a local oddity, but the latest IR surveys have shown that ULIRGs are vastly more numerous at high redshift, and tantalizing suggestions of physical differences between high and low redshift ULIRGs hint at differences in their formation modes and local environment. In this review we look at recent progress on understanding the physics and evolution of local ULIRGs, the contribution of high redshift ULIRGs to the cosmic infrared background and the global history of star formation, and the role of ULIRGs as diagnostics of the formation of massive galaxies and large-scale structures.Comment: Review article, published in "Astrophysics Update 2 - topical and timely reviews on astronomy and astrophysics". Ed. John W. Mason. Springer/Praxis books. ISBN: 3-540-30312-X. 53 pages, 5 figures. Higher quality figures available on reques

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Megamaser galaxies

Cited by 29 publications

References 36 publications

Global VLBI Observations of the Compact OH Megamaser Emission from III Zw 35 and IRAS 17208−0014

Global VLBI Observations of the Compact OH Megamaser Emission from III Zw 35 and IRAS 17208−0014

The middle infrared properties of OH megamaser host galaxies

Ultraluminous Infrared Galaxies

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