The Discovery of H
                    <sub>2</sub>
                    O Maser Emission in Seven Active Galactic Nuclei and at High Velocities in the Circinus Galaxy

Greenhill, L. J.; Kondratko, P. T.; Lovell, J. E. J.; Kuiper, T. B. H.; Moran, J. M.; Jauncey, D. L.; Baines, Graham

doi:10.1086/367602

Cited by 108 publications

(136 citation statements)

References 17 publications

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“…In Fig. 11, we show a plot with the water and OH maser isotropic luminosities (measured values for detections or 3σ upper limits in case of non (Greenhill et al 2003) Notes. (a) The isotropic luminosity is that of individual maser spots when the emission is spatially resolved.…”

Section: Kilomasers Revisitedmentioning

confidence: 99%

New H₂O masers in Seyfert and FIR bright galaxies

Tarchi

Castangia

Henkel

et al. 2010

A&A

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Context. Very luminous extragalactic water masers, the megamasers, are associated with active galactic nuclei (AGN) in galaxies characterized by accretion disks, radio jets, and nuclear outflows. Weaker masers, the kilomasers, seem to be related mostly to star formation activity, although the possibility exists that some of these sources may belong to the weak tail of the AGN maser distribution. Aims. It is particularly important to accurately locate the water maser emission to reveal its origin and shed light on extragalactic starforming activity or to elucidate the highly obscured central regions of galaxies. Methods. We performed interferometric observations of three galaxies, NGC 3556, Arp 299, and NGC 4151, where water emission was found. Statistical tools were used to study the relation between OH and H 2 O maser emission in galaxies. Results. The maser in NGC 3556 is associated with a compact radio continuum source that is most likely a supernova remnant or radio supernova. In Arp 299, the luminous water maser has been decomposed in three main emitting regions associated with the nuclear regions of the two main galaxies of the system, NGC 3690 and IC 694, and the region of overlap. In NGC 4151, only one of the two previously observed maser components has been tentatively detected. This feature, if real, is associated with the galaxy's central region. The only galaxy, so far, where luminous maser emission from two maser species, OH and H 2 O, has been confidently detected is Arp 299. Weaker masers from these two species instead coexist in a number of objects. A search for emission from both maser species in a larger number of galaxies is, however, needed to assess these last two results better.

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Section: Kilomasers Revisitedmentioning

confidence: 99%

New H₂O masers in Seyfert and FIR bright galaxies

Tarchi

Castangia

Henkel

et al. 2010

A&A

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“…Although it has a large angular size (≥80 ) at optical wavelengths and in atomic gas (Hi), Circinus was not discovered until the 1970s (Freeman et al 1977;Jones et al 1999), because it is located only ∼4 • above the Galactic plane with a Galactic visual extinction of 4.8 mag (e.g., Schlegel et al 1998). H 2 O mega-masers at both mm and submm wavelengths were found in the center of Circinus (e.g., Greenhill et al 2003;Hagiwara et al 2013), indicating a molecular torus around the central SMBH. The mass of the SMBH is estimated to be 1.7 ± 0.3 × 10 6 M (e.g., Greenhill et al 2003), and the torus accretion rate is as high as ∼20% of the Eddington luminosity (e.g., Tristram et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Zhang

Henkel

Gao

et al. 2014

A&A

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We report mapping observations of the 12 CO J = 3 → 2, 4 → 3, 6 → 5, and 7 → 6 transitions and the C i 3 P 1 → 3 P 0 (C i) 492 GHz transition toward the central 40 ×40 region of the Circinus galaxy, using the Atacama Pathfinder EXperiment (APEX) telescope. We also detected 13 CO J = 3 → 2 at the central position of Circinus. These observations are to date the highest CO transitions reported in Circinus. With large velocity gradient (LVG) modeling and likelihood analysis we try to obtain density, temperature, and column density of the molecular gas in three regions: the nuclear region (D < 18 ∼ 360 pc), the entire central 45 (D < 45 ∼ 900 pc) region, and the star-forming (S-F) ring (18 < D < 45 ). In the nuclear region, we can fit the CO excitation with a single excitation component, yielding an average condition of n H 2 ∼ 10 3.2 cm −3 , T kin ∼ 200 K, and d /dr ∼ 3 km s −1 pc −1 . In the entire 45 region, which covers both the nucleus and the S-F ring, two excitation components are needed with n H 2 ∼ 10 4.2 cm −3 and 10 3.0 cm −3 , T kin ∼ 60 K and 30 K, and M H 2 ∼ 2.3 × 10 7 M and 6.6 × 10 7 M , respectively. The gas excitation in the S-F ring can also be fitted with two LVG components, after subtracting the CO fluxes in the 18 nuclear region. The S-F ring region contributes 80% of the molecular mass in the 45 region. For the entire 45 region, we find a standard conversion factor of N(H 2 )/I CO 1→0 = 0.37 × 10 20 cm −2 (K km s −1 ) −1 , about 1/5 of the Galactic disk value. The luminosity ratios of C i and 12 CO J = 3 → 2 (R CI/CO 3→2 ) in Circinus basically follow a linear trend, similar to that obtained in high-redshift galaxies. The average R CI/CO J = 3 → 2 in Circinus is found to be ∼0.2, lying at an intermediate value between non-AGN nuclear regions and high-redshift galaxies.

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“…Red and blue-shifted emission are segregated on opposite sides of the central engine, but otherwise the maser structure is clumped with local velocity dispersions > 10% of the rotation speed. Between the two extremes are the relatively well-ordered mid-range cases of Circinus, which is somewhat clumpy but Keplerian to within modeling errors (Greenhill et al 2003b), and NGC 1068, which is moderately clumpy and distinctly sub-Keplerian Lodato & Bertin 2003).…”

Section: Mappingmentioning

confidence: 98%

“…See review by Greenhill (2002a). References: (1) Churchwell et al (1977), (2) Dos Santos & Lépine (1979), (3) Gardner & Whiteoak (1982), (4) Claussen & Lo (1986), (5) Claussen et al (1988), (6) Nakai, Inoue, & Miyoshi (1993), (7) Braatz et al (1996), (8) Greenhill et al (2002b), (9) Greenhill et al (1995), (10) Miyoshi et al (1995), (11) Gallimore et al (1996), (12) Claussen et al (1998) Greenhill et al (2003a), (14) Greenhill et al (2003b), (15) Kondratko et al (2006a), Braatz et al (2004), (17) Macri et al (2006), (18) Barvainis & Antonucci (2005), (19) Humphreys et al (2005), and (20) Braatz et al (this volume).…”

Section: Historymentioning

confidence: 99%

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Masers in AGN environments

Greenhill¹

2007

Proc. IAU

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Abstract.Galactic nuclei are well known sources of OH and H2O maser emission. It appears that intense star formation in ultra-luminous infrared galaxies drives most OH sources. In contrast, nuclear activity appears to drive most H2O sources. When H2O emission originates in accretion disk structures, constrained geometry and dynamics enable robust interpretation of spectroscopic and imaging data. The principal science includes study of AGN geometry at parsec and sub-parsec radii and measurement of geometric distances in the Hubble Flow. New high accuracy estimates of the "Hubble constant, H•" obtained from maser distances may enable new substantively improved constraints on fundamental cosmological parameters (e.g., dark energy).

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The Discovery of H ₂ O Maser Emission in Seven Active Galactic Nuclei and at High Velocities in the Circinus Galaxy

Cited by 108 publications

References 17 publications

New H₂O masers in Seyfert and FIR bright galaxies

New H₂O masers in Seyfert and FIR bright galaxies

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Masers in AGN environments

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The Discovery of H 2 O Maser Emission in Seven Active Galactic Nuclei and at High Velocities in the Circinus Galaxy

Cited by 108 publications

References 17 publications

New H2O masers in Seyfert and FIR bright galaxies

New H2O masers in Seyfert and FIR bright galaxies

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci3PP0observations

Masers in AGN environments

Contact Info

Product

Resources

About

The Discovery of H ₂ O Maser Emission in Seven Active Galactic Nuclei and at High Velocities in the Circinus Galaxy

New H₂O masers in Seyfert and FIR bright galaxies

New H₂O masers in Seyfert and FIR bright galaxies

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations