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Article: The circumnuclear molecular gas in the seyfert galaxy NGC 4945

TitleThe circumnuclear molecular gas in the seyfert galaxy NGC 4945
Authors
KeywordsGalaxies: Active
Galaxies: Individual (Ngc 4945)
Galaxies: Seyfert
Galaxies: Starburst Intergalactic Medium
Radio Lines: Galaxies
Issue Date2007
PublisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205
Citation
Astrophysical Journal Letters, 2007, v. 670 n. 1, p. 116-128 How to Cite?
AbstractWe have mapped the central region of NGC 4945 in the J = 2 →1 transition of 12CO, 13CO, and C 18O, as well as the continuum at ∼1.3 mm, at an angular resolution of 5" x 3" with the Submillimeter Array. The relative proximity of NGC 4945 (distance of only 3.8 Mpc) permits a detailed study of the circumnuclear molecular gas and dust in a galaxy exhibiting both an active galactic nucleus (AGN; classified as Seyfert 2) and a circumnuclear starburst in an inclined ring with radius ∼2.5" (∼50 pc). We infer the systemic velocity ∼585 km s _1 from chanel maps and PV-diagrams. We find that all three molecular lines trace an inclined rotating disk with the major axis aligned with that of the starburst ring and large-scale galactic disk and which exhibits solid-body rotation within a radius of ∼5" (∼95 pc). The rotation curve flattens beyond this radius, and the isovelocity contours exhibit an S-shaped asymmetry suggestive of a highly inclined bar, as has been invoked to produce a similar asymmetry observed on larger scales. We infer an inclination for the nuclear disk of 62° ± 2°, somewhat smaller than the inclination of the large-scale galactic disk of ∼78°. The continuum emission at 1.3 mm also extends beyond the starburst ring and is dominated by thermal emission from dust. If it traces the same dust emitting in the far-infrared, then the bulk of this dust must be heated by star-formation activity rather than the AGN. We discover a kinematically decoupled component at the center of the disk with a radius smaller than 1.4" (27 pc), but which spans approximately the same range of velocities as the surrounding disk. This component has a higher density than its surroundings and is a promising candidate for the circumnuclear molecular torus invoked by AGN unification models. © 2007. The American Astronomical Society. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/175108
ISSN
2015 Impact Factor: 5.487
2015 SCImago Journal Rankings: 3.369
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorChou, RCYen_US
dc.contributor.authorPeck, ABen_US
dc.contributor.authorLim, Jen_US
dc.contributor.authorMatsushita, Sen_US
dc.contributor.authorMuller, Sen_US
dc.contributor.authorSawadaSatoh, Sen_US
dc.contributor.authorDinhVTrungen_US
dc.contributor.authorBoone, Fen_US
dc.contributor.authorHenkel, Cen_US
dc.date.accessioned2012-11-26T08:49:15Z-
dc.date.available2012-11-26T08:49:15Z-
dc.date.issued2007en_US
dc.identifier.citationAstrophysical Journal Letters, 2007, v. 670 n. 1, p. 116-128en_US
dc.identifier.issn2041-8205en_US
dc.identifier.urihttp://hdl.handle.net/10722/175108-
dc.description.abstractWe have mapped the central region of NGC 4945 in the J = 2 →1 transition of 12CO, 13CO, and C 18O, as well as the continuum at ∼1.3 mm, at an angular resolution of 5" x 3" with the Submillimeter Array. The relative proximity of NGC 4945 (distance of only 3.8 Mpc) permits a detailed study of the circumnuclear molecular gas and dust in a galaxy exhibiting both an active galactic nucleus (AGN; classified as Seyfert 2) and a circumnuclear starburst in an inclined ring with radius ∼2.5" (∼50 pc). We infer the systemic velocity ∼585 km s _1 from chanel maps and PV-diagrams. We find that all three molecular lines trace an inclined rotating disk with the major axis aligned with that of the starburst ring and large-scale galactic disk and which exhibits solid-body rotation within a radius of ∼5" (∼95 pc). The rotation curve flattens beyond this radius, and the isovelocity contours exhibit an S-shaped asymmetry suggestive of a highly inclined bar, as has been invoked to produce a similar asymmetry observed on larger scales. We infer an inclination for the nuclear disk of 62° ± 2°, somewhat smaller than the inclination of the large-scale galactic disk of ∼78°. The continuum emission at 1.3 mm also extends beyond the starburst ring and is dominated by thermal emission from dust. If it traces the same dust emitting in the far-infrared, then the bulk of this dust must be heated by star-formation activity rather than the AGN. We discover a kinematically decoupled component at the center of the disk with a radius smaller than 1.4" (27 pc), but which spans approximately the same range of velocities as the surrounding disk. This component has a higher density than its surroundings and is a promising candidate for the circumnuclear molecular torus invoked by AGN unification models. © 2007. The American Astronomical Society. All rights reserved.en_US
dc.languageengen_US
dc.publisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205en_US
dc.relation.ispartofAstrophysical Journal Lettersen_US
dc.subjectGalaxies: Activeen_US
dc.subjectGalaxies: Individual (Ngc 4945)en_US
dc.subjectGalaxies: Seyferten_US
dc.subjectGalaxies: Starburst Intergalactic Mediumen_US
dc.subjectRadio Lines: Galaxiesen_US
dc.titleThe circumnuclear molecular gas in the seyfert galaxy NGC 4945en_US
dc.typeArticleen_US
dc.identifier.emailLim, J: jjlim@hku.hken_US
dc.identifier.authorityLim, J=rp00745en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1086/521351en_US
dc.identifier.scopuseid_2-s2.0-39049166128en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-39049166128&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume670en_US
dc.identifier.issue1en_US
dc.identifier.spage116en_US
dc.identifier.epage128en_US
dc.identifier.isiWOS:000250965400008-
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridChou, RCY=23491711900en_US
dc.identifier.scopusauthoridPeck, AB=7102267982en_US
dc.identifier.scopusauthoridLim, J=7403453870en_US
dc.identifier.scopusauthoridMatsushita, S=7201408992en_US
dc.identifier.scopusauthoridMuller, S=15071043100en_US
dc.identifier.scopusauthoridSawadaSatoh, S=6603503908en_US
dc.identifier.scopusauthoridDinhVTrung=6701469660en_US
dc.identifier.scopusauthoridBoone, F=8902646900en_US
dc.identifier.scopusauthoridHenkel, C=7005238136en_US

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