Extremely-high-velocity H20 maser emission in the galaxy NGC4258

Nakai, Naomasa; Inoue, Makoto; Miyoshi, Makoto

doi:10.1038/361045a0

Cited by 121 publications

(87 citation statements)

References 10 publications

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“…The first such galaxy to be observed was the nearby (D ≈ 7 Mpc) LINER spiral NGC 4258, which has a 22 GHz line luminosity L H 2 O ≈ 85 L . Most strikingly, NGC 4258 was already known from single-dish observations (Nakai, Inoue, & Miyoshi 1993) to show an enormous velocity spread in its maser emission, with V up to ±1000 km s −1 with respect to the systemic velocity. Combined with the already established concentration of the emission to the nucleus from earlier VLA observations (Claussen & Lo 1986), this strongly suggested that material very deep in a potential well -such as gas in proximity to a massive black hole -could be involved in the emission.…”

Section: Imaging 1: Ngc 4258mentioning

confidence: 99%

Powerful Water Masers in Active Galactic Nuclei

Maloney

2002

Publ. – Astron. Soc. Aust

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Luminous water maser emission in the 6_(16)-5_(23) line at 22 GHz has been detected from two dozen galaxies. In all cases the emission is confined to the nucleus and has been found only in AGN, in particular, in Type 2 Seyferts and LINERs. I argue that most of the observed megamaser sources are powered by X-ray irradiation of dense gas by the central engine. After briefly reviewing the physics of these X-Ray Dissociation Regions, I discuss in detail the observations of the maser disk in NGC 4258, its implications, and compare alternative models for the maser emission. I then discuss the observations of the other sources that have been imaged with VLBI to date, and how they do or do not fit into the framework of a thin, rotating disk, as in NGC 4258. Finally, I briefly discuss future prospects, especially the possibility of detecting other water maser transitions.Comment: 45 pages, 16 figures. Refereed and greatly expanded version of my review talk at the ASA meeting in Lorne, July 2001. To appear in Proceedings of the Astronomical Society of Australi

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Section: Imaging 1: Ngc 4258mentioning

confidence: 99%

Powerful Water Masers in Active Galactic Nuclei

Maloney

2002

Publ. – Astron. Soc. Aust

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“…They suggested that these masers might arise in gas associated with dust-laden molecular tori that had been proposed to surround black holes by Antonucci & Miller (1985). Nakai, Inoue, & Miyoshi (1993), with a powerful new spectrometer of 16,000 channels spanning a velocity range of 3000 km s −1 , observed NGC 4258 and discovered satellite line clusters offset from the systemic velocity by about ± 1000 km s −1 , which are shown in Figure 3 (see also Miyoshi 1999). …”

Section: Cosmic Masersmentioning

confidence: 99%

Observational evidence for massive black holes in the centers of active galaxies

1999

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Naturally occurring water vapor maser emission at 1.35 cm wavelength provides an accurate probe for the study of accretion disks around highly compact objects, thought to be black holes, in the centers of active galaxies. Because of the exceptionally fine angular resolution, 200 microarcseconds, obtainable with very long baseline interferometry, accompanied by high spectral resolution, < 0.1 km s −1 , the dynamics and structures of these disks can be probed with exceptional clarity. The data on the galaxy NGC 4258 are discussed here in detail. The mass of the black hole binding the accretion disk is 3.9 × 10 7 M ⊙ . Although the accretion disk has a rotational period of about 800 years, the physical motions of the masers have been directly measured with VLBI over a period of a few years. These measurements also allow the distance from the earth to the black hole to be estimated to an accuracy of 4 percent. The status of the search for other maser/black hole candidates is also discussed.

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“…One highlight was the discovery of high-velocity H 2 O maser emission in the nucleus of NGC 4258, offset by ± 1000 km s −1 from their host galaxy in systemic velocity (e.g., Nakai et al 1993;Miyoshi et al 1995;Herrnstein et al 1999). This led to the discovery of so-called disk masers, which trace subparsec edge-on Keplerian disks that surround supermassive black holes (SMBHs).…”

Section: Introductionmentioning

confidence: 99%

Radio continuum of galaxies with H₂O megamaser disks: 33 GHz VLA data

Kamali

Henkel

Brunthaler

et al. 2017

A&A

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Context. Galaxies with H 2 O megamaser disks are active galaxies in whose edge-on accretion disks 22 GHz H 2 O maser emission has been detected. Because their geometry is known, they provide a unique view into the properties of active galactic nuclei. Aims. The goal of this work is to investigate the nuclear environment of galaxies with H 2 O maser disks and to relate the maser and host galaxy properties to those of the radio continuum emission of the galaxy. Methods. The 33 GHz (9 mm) radio continuum properties of 24 galaxies with reported 22 GHz H 2 O maser emission from their disks are studied in the context of the multiwavelength view of these sources. The 29-37 GHz Ka-band observations are made with the Jansky Very Large Array in B, CnB, or BnA configurations, achieving a resolution of ∼ 0.2 -0.5 arcseconds. Hard X-ray data from the Swift/BAT survey and 22 µm infrared data from WISE, 22 GHz H 2 O maser data and 1.4 GHz data from NVSS and FIRST surveys are also included in the analysis. Results. Eighty-seven percent (21 out of 24) galaxies in our sample show 33 GHz radio continuum emission at levels of 4.5 -240 σ. Five sources show extended emission (deconvolved source size larger than 2.5 times the major axis of the beam), including one source with two main components and one with three main components. The remaining detected 16 sources (and also some of the above-mentioned targets) exhibit compact cores within the sensitivity limits. Little evidence is found for extended jets (>300 pc) in most sources. Either they do not exist, or our chosen frequency of 33 GHz is too high for a detection of these supposedly steep spectrum features. In only one source among those with known maser disk orientation, NGC 4388, did we find an extended jet-like feature that appears to be oriented perpendicular to the H 2 O megamaser disk. NGC 2273 is another candidate whose radio continuum source might be elongated perpendicular to the maser disk. Smaller 100-300 pc sized jets might also be present, as is suggested by the beam-deconvolved morphology of our sources. Whenever possible, central positions with accuracies of 20-280 mas are provided. A correlation analysis shows that the 33 GHz luminosity weakly correlates with the infrared luminosity. The 33 GHz luminosity is anticorrelated with the circular velocity of the galaxy. The black hole masses show stronger correlations with H 2 O maser luminosity than with 1.4 GHz, 33 GHz, or hard X-ray luminosities. Furthermore, the inner radii of the disks show stronger correlations with 1.4 GHz, 33 GHz, and hard X-ray luminosities than their outer radii, suggesting that the outer radii may be affected by disk warping, star formation, or peculiar density distributions.

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Extremely-high-velocity H20 maser emission in the galaxy NGC4258

Cited by 121 publications

References 10 publications

Powerful Water Masers in Active Galactic Nuclei

Powerful Water Masers in Active Galactic Nuclei

Observational evidence for massive black holes in the centers of active galaxies

Radio continuum of galaxies with H₂O megamaser disks: 33 GHz VLA data

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Extremely-high-velocity H20 maser emission in the galaxy NGC4258

Cited by 121 publications

References 10 publications

Powerful Water Masers in Active Galactic Nuclei

Powerful Water Masers in Active Galactic Nuclei

Observational evidence for massive black holes in the centers of active galaxies

Radio continuum of galaxies with H2O megamaser disks: 33 GHz VLA data

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Radio continuum of galaxies with H₂O megamaser disks: 33 GHz VLA data