The Water Masers in the Elliptical Galaxy NGC 1052

Claussen, M. J.; Diamond, P. J.; Braatz, J. A.; Wilson, A. S.; Henkel, C.

doi:10.1086/311405

Cited by 125 publications

(159 citation statements)

References 17 publications

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“…It shows a velocity gradient of ∼ 200 km s −1 mas −1 along this direction. We note that Claussen et al (1998) showed a velocity gradient along the east-west direction (∼ 100 km s −1 mas −1 ) in the maser cluster of the west jet component.…”

Section: H 2 O Maser Emissionmentioning

confidence: 68%

Positional coincidence between an H₂O maser and a plasma torus in NGC 1052

et al. 2007

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Abstract. We present VLBA observation towards the nucleus of a nearby radio galaxy NGC 1052. In NGC 1052, two-sided jet structure and a dense plasma circumnuclear torus with a radius of 0.7 pc have been found around the central mass. It emits a H2 O megamaser, which is redshifted with respect to the systemic velocity of the galaxy (1491 km s −1 ) with a large velocity width of 100 km s −1 (FWHM). The maser gas is found at the inner jet components of both the approaching and receding jets. The maser gas is positionally coincident with a plasma torus. The maser gas in NGC 1052 could be explained as a circumnuclear torus or disk, as found for the nucleus of NGC 4258.Keywords. galaxies: active, galaxies: individual(NGC 1052), galaxies: H2 O maser Free-free absorption opacity distributionThe continuum images at 15, 22 and 43 GHz show the two-sided jet structure which consists of several components. After restoring with a same beam size, we obtained spectral indices along the jets. The spectral indices indicate that most parts of the two-side jet structure have optically thin spectra at 15-43 GHz except its inner edge part; a steeply inverted spectrum (α = 3.2; S ∝ ν −α ) is revealed between B and C3. The spectrum index exceeds the theoretical limit for synchrotron self-absorption (α = 2.5). The highly inverted spectrum of the inner edge of the jets implies that synchrotron emission is obscured through free-free absorption (FFA) by the foreground dense plasma, and it is consistent with past multi-frequency observations (Kameno et al. 2001, Vermeulen et al. 2003and Kadler et al. 2004.Fitting the continuum spectrum at 15-43 GHz to FFA model (S ν ∝ ν −α exp (−τ ν −2.1 )), we obtained FFA opacity (τ ) distributions along the jet axis (figure 1), which reveals that a high opacity (τ > 1000) is found in the inner edge. It implies that the dense cold plasma covers ∼2 mas in the inner edge of the jets, where the central engine is supposed to exist. H 2 O maser emissionIn our observation, significant maser emission within the velocity range of 1550-1850 km s −1 was detected. The maser spots consists of two clusters; the east cluster and the west cluster are located at Component B and C3, respectively. The velocity range of the east cluster is 1550-1850 km s −1 , which is the same as the whole velocity width † Present address:

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Section: H 2 O Maser Emissionmentioning

confidence: 68%

Positional coincidence between an H₂O maser and a plasma torus in NGC 1052

et al. 2007

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“…Nearly a decade later, studies of NGC 4258 were the first to demonstrate that the emission in fact originates from annuli in the still more compact, relatively thin disks at radii on the order of 0.1 to 1 pc Greenhill et al 1995). Two additional contexts for maser emission were identified later: (1) downstream from central engines in association with radio jets (Gallimore et al 1996;Claussen et al 1998;Sawada-Satoh, this meeting) and (2) wide-angle outflows of AGN narrow-line regions (Greenhill et al 2003a). Santos (1977) reported an earlier detection possibly toward the nucleus of NGC 253, but independent studies failed to confirm it.…”

Section: Historymentioning

confidence: 99%

“…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%

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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“…In these sources, the amplified emission is the result of an interaction between the radio jet and the encroaching molecular clouds. The only known sources in this class are NGC 1068 (Gallimore et al 1996) and the Circinus galaxy (Greenhill et al 2001) which appear to have both circumnuclear disk masers and maser emission arising along the edges of an ionisation cone or outflow, and NGC 1052, in which the masers appear to arise along the jet (Claussen et al 1998).…”

Section: Jet Masersmentioning

confidence: 99%

Disks, tori, and cocoons: emission and absorption diagnostics of AGN environments

Morganti¹,

Greenhill

Peck

et al. 2004

New Astronomy Reviews

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One of the most important problems in the study of active galaxies is understanding the detailed geometry, physics, and evolution of the central engines and their environments. The leading models involve an accretion disk and torus structure around a central dense object, thought to be a supermassive black hole. Gas found in the environment of AGN is associated with different structures: molecular accretion disks, larger scale atomic tori, ionized and neutral "cocoons" in which the nuclear regions can be embedded. All of them can be studied at radio wavelengths by various means. Here, we summarize the work that has been done to date in the radio band to characterize these structures. Much has been learned about the central few parsecs of AGN in the last few decades with contemporary instruments but the picture remains incomplete. In order to be able to define a more accurate model of this region, significant advances in sensitivity, spectral and angular resolution, and bandpass stability are required. The necessary advances will only be provided by the Square Kilometer Array and we discuss the possibilities that these dramatic improvements will open for the study of the gas in the central region of AGN.

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The Water Masers in the Elliptical Galaxy NGC 1052

Cited by 125 publications

References 17 publications

Positional coincidence between an H₂O maser and a plasma torus in NGC 1052

Positional coincidence between an H₂O maser and a plasma torus in NGC 1052

Masers in AGN environments

Disks, tori, and cocoons: emission and absorption diagnostics of AGN environments

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The Water Masers in the Elliptical Galaxy NGC 1052

Cited by 125 publications

References 17 publications

Positional coincidence between an H2O maser and a plasma torus in NGC 1052

Positional coincidence between an H2O maser and a plasma torus in NGC 1052

Masers in AGN environments

Disks, tori, and cocoons: emission and absorption diagnostics of AGN environments

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Product

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Positional coincidence between an H₂O maser and a plasma torus in NGC 1052

Positional coincidence between an H₂O maser and a plasma torus in NGC 1052