A Survey for H 2O Megamasers in Active Galactic Nuclei. I. Observations

Braatz, J. A.; Wilson, A. S.; Henkel, C.

doi:10.1086/192328

Cited by 137 publications

(168 citation statements)

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“…References.-(1) Greenhill et al 2007, in preparation; (2) ; (3) Molendi et al 2003;(18) Kondratko et al 2006b;(19) Guainazzi et al 2005;(20) Kondratko et al 2005; (21) Iyomoto et al 2001;(22) Braatz et al 1996;(23) Argon et al 2007, and references therein; (24) Fruscione et al 2005;(25) this paper. …”

Section: Comparison With Other H 2 O Disk Maser Host Galaxiesmentioning

confidence: 97%

A Deep 0.3–10 keV Spectrum of the H₂O Maser Galaxy IC 2560

Tilak

Greenhill

Done

et al. 2008

ApJ

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We present a new XMM-Newton spectrum of the Seyfert 2 nucleus of IC 2560, which hosts H 2 O maser emission from an inclined Keplerian accretion disk. The X-ray spectrum shows soft excess due to multitemperature ionized plasma, a hard continuum, and strong emission features, from Mg, Si, S, Ca, Fe, and Ni, mainly due to fluorescence. It is consistent with reflection of the continuum from a mostly neutral medium and obscuration due to a high column density, >10 24 cm À2 . The amplitude of the reflected component may exceed 10% of the central unobscured luminosity. This is higher than the reflected fraction of a few percent observed in other Seyfert 2 sources such as NGC 4945. We observe an emission line at 6.7 keV, possibly due to Fe xxv, undetected in previous Chandra observations. The absorption column density associated with this line is less than 10 23 cm À2 , which is lower than the obscuration of the central source. We hypothesize that this highly ionized Fe line emission originates in warm gas, which is also responsible for a scattered component of continuum emission that may dominate the spectrum between 1 and 3 keV. We compare X-ray and maser emission characteristics of IC 2560 and other AGNs that exhibit water maser emission originating in disk structures around central engines. The temperature for the region of the disk associated with maser action is consistent with the expected 400Y1000 K range. The clumpiness of disk structures (inferred from the maser distribution) may depend on the unobscured luminosities of the central engines.

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Section: Comparison With Other H 2 O Disk Maser Host Galaxiesmentioning

confidence: 97%

A Deep 0.3–10 keV Spectrum of the H₂O Maser Galaxy IC 2560

Tilak

Greenhill

Done

et al. 2008

ApJ

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“…Somewhat more than 50 have been detected (see Figure 3 in Greenhill, this Volume). The phenomenon is associated generally with Seyfert-2 galaxies and LINERS (Braatz et al 1996), though there are examples in narrow line Seyfert-1 systems (Hagiwara et al 2003), transition objects between Seyfert 1 and 2 classes (e.g., Braatz et al 1996), and FR-II radio galaxies (Tarchi et al 2003). The spectra of almost half the known masers exhibit emission over a broad range of velocity that (more or less) symmetrically brackets the systemic velocities of the host galaxies.…”

Section: What Are Nuclear H 2 O Masers?mentioning

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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“…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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A Survey for H 2O Megamasers in Active Galactic Nuclei. I. Observations

Cited by 137 publications

References 0 publications

A Deep 0.3–10 keV Spectrum of the H₂O Maser Galaxy IC 2560

A Deep 0.3–10 keV Spectrum of the H₂O Maser Galaxy IC 2560

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

Masers in AGN environments

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A Survey for H 2O Megamasers in Active Galactic Nuclei. I. Observations

Cited by 137 publications

References 0 publications

A Deep 0.3–10 keV Spectrum of the H2O Maser Galaxy IC 2560

A Deep 0.3–10 keV Spectrum of the H2O Maser Galaxy IC 2560

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

Masers in AGN environments

Contact Info

Product

Resources

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A Deep 0.3–10 keV Spectrum of the H₂O Maser Galaxy IC 2560

A Deep 0.3–10 keV Spectrum of the H₂O Maser Galaxy IC 2560