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Article: The central region of the nearby Seyfert 2 galaxy NGC4945: A pair of spirals

TitleThe central region of the nearby Seyfert 2 galaxy NGC4945: A pair of spirals
Authors
Keywordsgalaxies: individual (NGC 4945)
galaxies: kinematics and dynamics
galaxies: spiral
galaxies: structure
Issue Date2011
PublisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205
Citation
Astrophysical Journal Letters, 2011, v. 731 n. 1 How to Cite?
AbstractNGC4945 is a Seyfert 2 galaxy at a distance of 3.82Mpc. Its relative proximity has permitted a detailed Submillimeter Array study of the circumnuclear molecular gas in a galaxy exhibiting an active galactic nucleus (AGN). Based on an analysis of the high-resolution velocity field of the central region (20″ × 20″, 1″ = 19pc), we demonstrate that the S-shaped structure of the isovelocity contours is well reproduced by the numerical results of a two-dimensional hydrodynamical simulation. In particular, the velocity structure is represented by the bending produced by a shock along the spiral density waves, which are excited at the outer-inner Lindblad resonance (OILR) by a fast rotating bar. The simulated density map reveals a pair of tightly wound spirals in the center which pass through most of the ring-like (claimed to be a circumnuclear starburst ring by other authors) high-intensity region in the observations as well as intersect several Paα emission line knots located outside the ring-like region. The calculated mass inflow rate at a scale of 50pc is about three times the inferred mass accretion rate of the AGNs of NGC4945. We find that self-gravity of the gas is important and should be included in our model for NGC4945. The model is compared with the gas orbit model discussed in Lim etal., and it is shown that the hydrodynamic model provides a better match to the observed position-velocity diagram and, hence, provides a more reliable prediction of the OILR position. © 2011. The American Astronomical Society. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/139610
ISSN
2015 Impact Factor: 5.487
2015 SCImago Journal Rankings: 3.369
ISI Accession Number ID
Funding AgencyGrant Number
Theoretical Institute for Advanced Research in Astrophysics (TIARA)
Funding Information:

We thank the referee for his/her comments which helped to significantly improve the clarity and presentation of this work. L.-H. L. and R. E. T. acknowledge the support of the Theoretical Institute for Advanced Research in Astrophysics (TIARA) operated under the Academia Sinica Institute of Astronomy & Astrophysics in Taipei, Taiwan.

References

 

DC FieldValueLanguage
dc.contributor.authorLin, LHen_HK
dc.contributor.authorTaam, REen_HK
dc.contributor.authorYen, DCCen_HK
dc.contributor.authorMuller, Sen_HK
dc.contributor.authorLim, Jen_HK
dc.date.accessioned2011-09-23T05:52:38Z-
dc.date.available2011-09-23T05:52:38Z-
dc.date.issued2011en_HK
dc.identifier.citationAstrophysical Journal Letters, 2011, v. 731 n. 1en_HK
dc.identifier.issn2041-8205en_HK
dc.identifier.urihttp://hdl.handle.net/10722/139610-
dc.description.abstractNGC4945 is a Seyfert 2 galaxy at a distance of 3.82Mpc. Its relative proximity has permitted a detailed Submillimeter Array study of the circumnuclear molecular gas in a galaxy exhibiting an active galactic nucleus (AGN). Based on an analysis of the high-resolution velocity field of the central region (20″ × 20″, 1″ = 19pc), we demonstrate that the S-shaped structure of the isovelocity contours is well reproduced by the numerical results of a two-dimensional hydrodynamical simulation. In particular, the velocity structure is represented by the bending produced by a shock along the spiral density waves, which are excited at the outer-inner Lindblad resonance (OILR) by a fast rotating bar. The simulated density map reveals a pair of tightly wound spirals in the center which pass through most of the ring-like (claimed to be a circumnuclear starburst ring by other authors) high-intensity region in the observations as well as intersect several Paα emission line knots located outside the ring-like region. The calculated mass inflow rate at a scale of 50pc is about three times the inferred mass accretion rate of the AGNs of NGC4945. We find that self-gravity of the gas is important and should be included in our model for NGC4945. The model is compared with the gas orbit model discussed in Lim etal., and it is shown that the hydrodynamic model provides a better match to the observed position-velocity diagram and, hence, provides a more reliable prediction of the OILR position. © 2011. The American Astronomical Society. All rights reserved.en_HK
dc.languageengen_US
dc.publisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205en_HK
dc.relation.ispartofAstrophysical Journal Lettersen_HK
dc.rightsThe Astrophysical Journal. Copyright © Institute of Physics Publishing, Inc.-
dc.subjectgalaxies: individual (NGC 4945)en_HK
dc.subjectgalaxies: kinematics and dynamicsen_HK
dc.subjectgalaxies: spiralen_HK
dc.subjectgalaxies: structureen_HK
dc.titleThe central region of the nearby Seyfert 2 galaxy NGC4945: A pair of spiralsen_HK
dc.typeArticleen_HK
dc.identifier.emailLim, J: jjlim@hku.hken_HK
dc.identifier.authorityLim, J=rp00745en_HK
dc.description.naturelink_to_OA_fulltext-
dc.identifier.doi10.1088/0004-637X/731/1/15en_HK
dc.identifier.scopuseid_2-s2.0-79955012718en_HK
dc.identifier.hkuros193229en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-79955012718&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume731en_HK
dc.identifier.issue1en_HK
dc.identifier.isiWOS:000289772800015-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridLin, LH=24830821200en_HK
dc.identifier.scopusauthoridTaam, RE=7003756329en_HK
dc.identifier.scopusauthoridYen, DCC=24072648800en_HK
dc.identifier.scopusauthoridMuller, S=15071043100en_HK
dc.identifier.scopusauthoridLim, J=7403453870en_HK

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