AGN and Megamasers

AbstractLuminous extragalactic masers are traditionally referred to as the ‘megamasers’. Those produced by water molecules are associated with accretion disks, radio jets, or outflows in the nuclear regions of active galactic nuclei (AGN). The majority of OH maser sources are instead driven by intense star formation in ultra-luminous infrared galaxies, although in a few cases the OH maser emission traces rotating (toroidal or disk) structures around the nuclear engines of AGN. Thus, detailed maser studies provide a fundamental contribution to our knowledge of the main nuclear components of AGN, constitute unique tools to measure geometric distances of host galaxies, and have a great impact on probing the, so far, paradigmatic Unified Model of AGN.

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HEAVILY OBSCURED ACTIVE GALACTIC NUCLEI IN HIGH-REDSHIFT LUMINOUS INFRARED GALAXIES

The Astrophysical Journal ◽

10.1088/2041-8205/722/2/l238 ◽

2010 ◽

Vol 722 (2) ◽

pp. L238-L243 ◽

Cited By ~ 33

Author(s):

Ezequiel Treister ◽

C. Megan Urry ◽

Kevin Schawinski ◽

Carolin N. Cardamone ◽

David B. Sanders

Keyword(s):

Active Galactic Nuclei ◽

High Redshift ◽

Galactic Nuclei ◽

Infrared Galaxies ◽

Luminous Infrared Galaxies

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Masers in AGN environments

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307013439 ◽

2007 ◽

Vol 3 (S242) ◽

pp. 381-390 ◽

Cited By ~ 4

Author(s):

L. J. Greenhill

Keyword(s):

Cosmological Parameters ◽

Galactic Nuclei ◽

Hubble Constant ◽

High Accuracy ◽

Imaging Data ◽

Infrared Galaxies ◽

Nuclear Activity ◽

Luminous Infrared Galaxies ◽

Constrained Geometry ◽

Intense Star Formation

AbstractGalactic 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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5.1. Molecular gas in luminous galactic nuclei

Symposium - International Astronomical Union ◽

10.1017/s0074180900084631 ◽

1998 ◽

Vol 184 ◽

pp. 205-212

Author(s):

N. Z. Scoville ◽

A. J. Baker

Keyword(s):

Near Infrared ◽

Galactic Nuclei ◽

Infrared Emission ◽

Molecular Gas ◽

Luminous Infrared Galaxies ◽

Radio Jets ◽

Mass Fractions ◽

Ngc 1068 ◽

Nuclear Regions ◽

Lower Luminosity

In the last five years, millimeter-wave interferometry has clearly shown the existence of enormous masses (109–1010 M⊙) of molecular gas concentrated in the nuclear regions (R < 500 pc) of many luminous and ultra-luminous infrared galaxies. In these systems, molecular gas is an obvious source of fuel for nuclear starbursts and active galactic nuclei (AGN). For nearer, lower-luminosity systems there exists less systematic characterization of either the properties or the structure of the nuclear gas. Here we review recent results on the molecular gas in the nuclei of two near, lower-luminosity systems (M51 and NGC 1068) and contrast these results with those for the best studied ultra-luminous IRAS galaxy, Arp 220. For all three galaxies, there now exists CO(2–1) interferometry at high resolution which reveals, for the first time, disks of extremely dense, highly excited gas on scales of 50-300 pc. These structures vary in their levels of axisymmetry, thickness, and clumpiness. However, they share the ability to extinguish optical and near-infrared emission from active or stellar nuclei and perhaps to collimate radio jets and ionized outflows. Within the nuclear regions of these three galaxies, the molecular gas constitutes 10-50% of the total mass, with the most luminous systems having the highest gas mass-fractions.

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Infrared to Millimeter Spectroscopy and Imaging of Active Galactic Nuclei

International Astronomical Union Colloquium ◽

10.1017/s0252921100040355 ◽

1997 ◽

Vol 159 ◽

pp. 312-324

Author(s):

R. Genzel ◽

D. Lutz ◽

E. Sturm ◽

L. Tacconi ◽

N. Thatte ◽

...

Keyword(s):

Active Galactic Nuclei ◽

Near Infrared ◽

Galactic Nuclei ◽

Emission Lines ◽

Wavelength Band ◽

Infrared Galaxies ◽

Physical Processes ◽

Luminous Infrared Galaxies ◽

Ngc 1068 ◽

Millimeter Spectroscopy

AbstractObservations in the 1 µm to 1 cm wavelength band give important information on the physical processes occurring in and immediately around active galactic nuclei. Concentrating on recent results on ionic, atomic, and molecular emission lines, we discuss as examples the first ISO results on the nature of ultra-luminous infrared galaxies, and near-infrared and millimeter measurements of the central 100 parsecs of the Seyfert 2 galaxy NGC 1068.

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Obscured Active Galactic Nuclei in Luminous Infrared Galaxies

The Astrophysical Journal ◽

10.1086/177863 ◽

1996 ◽

Vol 470 ◽

pp. 222 ◽

Cited By ~ 46

Author(s):

L. M. Shier ◽

M. J. Rieke ◽

G. H. Rieke

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Infrared Galaxies ◽

Luminous Infrared Galaxies

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12CO(J = 1-0) Mapping of the Merging Galaxy NGC 3310

International Astronomical Union Colloquium ◽

10.1017/s0252921100020066 ◽

1994 ◽

Vol 140 ◽

pp. 374-375

Author(s):

T. Kikumoto ◽

Y. Taniguchi ◽

M. Suzuki ◽

K. Tomisaka

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Molecular Gas ◽

Beam Size ◽

Comprehensive Understanding ◽

Molecular Line ◽

Merging Galaxies ◽

Nuclear Regions ◽

Luminous Objects ◽

Intense Star Formation

Since molecular gas clouds in nuclear regions play important roles on both the intense star formation and fueling active galactic nuclei, a large number of molecular-line observations have been made for starburst, Seyfert, and merging galaxies. Recently, millimeter-wave arrays have been used to study circumnuclear molecular gas in merging galaxies. Most of them, however, have been devoted to the observations of more luminous objects such as ultra-luminous merging galaxies (ULMGs) discovered by IRAS (Sanders et al. 1988). In order to obtain a comprehensive understanding, it is necessary to study less-luminous merging galaxies. With this motivation, we present results of CO mapping of NGC 3310 which is one of less luminous merger candidates (LFIR = 2.5 × 1010Lʘ).The central region (5.1 kpc in diameter) of NGC 3310 was observed in CO(J = 1 − 0) using the Nobeyama Millimeter Array. The synthesized beam size was 6″.3 × 6″.1, which corresponds to 500 × 480 pc at the distance 16.3 Mpc. Our main results and conclusions are summarized as follows.

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Peering into the heart of darkness: Radio VLBI survey of the NEP deep field

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320003385 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 366-366

Author(s):

Joseph Gelfand

Keyword(s):

Active Galactic Nuclei ◽

Angular Resolution ◽

Galactic Nuclei ◽

Powerful Radio ◽

Host Galaxies ◽

Radio Jets ◽

Heart Of Darkness ◽

Multi Wavelength ◽

Initial Results ◽

Size Scales

AbstractActive Galactic Nuclei (AGN), accreting supermassive black holes at the centers of galaxies, are believed to produce powerful outflows – often observed as radio jets – which significantly influence the evolution of the surrounding galaxy and inter-galactic medium. However, how these jets – which are produced in the central parsecs of the AGN – impact gas on scales thousands to millions times larger is poorly understood. Doing so requires measuring the properties on all the relevant size scales. In this talk I will present initial results from the deepest-ever radio VLBI survey of an extragalactic field, whose milli-arcsecond angular resolution allows us to probe the central parsecs around these AGN. By comparing the radio properties of the detected radio jets with the multi-wavelength properties of their host galaxies, we are better to understand what galaxies generate powerful radio jets, and how do these outflows affect their host galaxies.

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Nature of Compton-thick Active Galactic Nuclei in “Nonmerging” Luminous Infrared Galaxies UGC 2608 and NGC 5135 Revealed with Broadband X-Ray Spectroscopy

The Astrophysical Journal ◽

10.3847/1538-4357/ab94b1 ◽

2020 ◽

Vol 897 (1) ◽

pp. 107

Author(s):

Satoshi Yamada ◽

Yoshihiro Ueda ◽

Atsushi Tanimoto ◽

Saeko Oda ◽

Masatoshi Imanishi ◽

...

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Infrared Galaxies ◽

X Ray ◽

Luminous Infrared Galaxies

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Spectroscopy of Luminous Infrared Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900112860 ◽

1999 ◽

Vol 186 ◽

pp. 295-301

Author(s):

S. Veilleux

Keyword(s):

Energy Source ◽

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Starburst Galaxies ◽

Infrared Galaxies ◽

Luminous Infrared Galaxies ◽

Main Emphasis ◽

Infrared Spectroscopic ◽

Evolutionary Phase

A review of recent optical and infrared spectroscopic results on luminous infrared galaxies is presented. The main emphasis is on the ultraluminous objects. Possible correlations with infrared luminosity are identified. These results are used to constrain the nature of the dominant energy source in luminous infrared galaxies, and to test whether these objects may represent an evolutionary phase between starburst galaxies and active galactic nuclei.

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