Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12386/28329
DC Field | Value | Language |
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dc.contributor.author | Henkel, C. | en_US |
dc.contributor.author | Mühle, S. | en_US |
dc.contributor.author | Bendo, G. | en_US |
dc.contributor.author | Józsa, G. I. G. | en_US |
dc.contributor.author | Gong, Y. | en_US |
dc.contributor.author | Viti, S. | en_US |
dc.contributor.author | Aalto, S. | en_US |
dc.contributor.author | Combes, F. | en_US |
dc.contributor.author | García-Burillo, S. | en_US |
dc.contributor.author | HUNT, Leslie Kipp | en_US |
dc.contributor.author | Mangum, J. | en_US |
dc.contributor.author | Martín, S. | en_US |
dc.contributor.author | Muller, S. | en_US |
dc.contributor.author | Ott, J. | en_US |
dc.contributor.author | van der Werf, P. | en_US |
dc.contributor.author | Malawi, A. A. | en_US |
dc.contributor.author | Ismail, H. | en_US |
dc.contributor.author | Alkhuja, E. | en_US |
dc.contributor.author | Asiri, H. M. | en_US |
dc.contributor.author | Aladro, R. | en_US |
dc.contributor.author | Alves, F. | en_US |
dc.contributor.author | Ao, Y. | en_US |
dc.contributor.author | Baan, W. A. | en_US |
dc.contributor.author | Costagliola, F. | en_US |
dc.contributor.author | Fuller, G. | en_US |
dc.contributor.author | Greene, J. | en_US |
dc.contributor.author | Impellizzeri, C. M. V. | en_US |
dc.contributor.author | Kamali, F. | en_US |
dc.contributor.author | Klessen, R. S. | en_US |
dc.contributor.author | Mauersberger, R. | en_US |
dc.contributor.author | Tang, X. D. | en_US |
dc.contributor.author | Tristram, K. | en_US |
dc.contributor.author | Wang, M. | en_US |
dc.contributor.author | Zhang, J. S. | en_US |
dc.date.accessioned | 2020-11-13T15:07:27Z | - |
dc.date.available | 2020-11-13T15:07:27Z | - |
dc.date.issued | 2018 | en_US |
dc.identifier.issn | 0004-6361 | en_US |
dc.identifier.uri | http://hdl.handle.net/20.500.12386/28329 | - |
dc.description.abstract | NGC 4945 is one of the nearest (D ≈ 3.8 Mpc; 1″ ≈ 19 pc) starburst galaxies. To investigate the structure, dynamics, and composition of the dense nuclear gas of this galaxy, ALMA band 3 (λ ≈ 3-4 mm) observations were carried out with ≈2″ resolution. Three HCN and two HCO<SUP>+</SUP> isotopologues, CS, C<SUB>3</SUB>H<SUB>2</SUB>, SiO, HCO, and CH<SUB>3</SUB>C<SUB>2</SUB>H were measured. Spectral line imaging demonstrates the presence of a rotating nuclear disk of projected size 10″ × 2″ reaching out to a galactocentric radius of r ≈ 100 pc with position angle PA = 45° ± 2°, inclination i = 75° ± 2° and an unresolved bright central core of size ≲2″. The continuum source, representing mostly free-free radiation from star forming regions, is more compact than the nuclear disk by a linear factor of two but shows the same position angle and is centered 0.''39 ± 0.''14 northeast of the nuclear accretion disk defined by H<SUB>2</SUB>O maser emission. Near the systemic velocity but outside the nuclear disk, both HCN J = 1 → 0 and CS J = 2 → 1 delineate molecular arms of length ≳15″ (≳285 pc) on opposite sides of the dynamical center. These are connected by a (deprojected) ≈ 0.6 kpc sized molecular bridge, likely a dense gaseous bar seen almost ends-on, shifting gas from the front and back side into the nuclear disk. Modeling this nuclear disk located farther inside (r ≲100 pc) with tilted rings provides a good fit by inferring a coplanar outflow reaching a characteristic deprojected velocity of ≈50 km s<SUP>-1</SUP>. All our molecular lines, with the notable exception of CH<SUB>3</SUB> C<SUB>2</SUB>H, show significant absorption near the systemic velocity (≈571 km s<SUP>-1</SUP>), within the range ≈500-660 km s<SUP>-1</SUP>. Apparently, only molecular transitions with low critical H<SUB>2</SUB> density (n<SUB>crit</SUB> ≲ 10<SUP>4</SUP> cm<SUP>-3</SUP>) do not show absorption. The velocity field of the nuclear disk, derived from CH<SUB>3</SUB> C<SUB>2</SUB>H, provides evidence for rigid rotation in the inner few arcseconds and a dynamical mass of M<SUB>tot</SUB> = (2.1 ± 0.2) × 10<SUP>8</SUP> M<SUB>☉</SUB> inside a galactocentric radius of 2.''45 (≈45 pc), with a significantly flattened rotation curve farther out. Velocity integrated line intensity maps with most pronounced absorption show molecular peak positions up to ≈1.''5 (≈30 pc) southwest of the continuum peak, presumably due to absorption, which appears to be most severe slightly northeast of the nuclear maser disk. A nitrogen isotope ratio of <SUP>14</SUP>N/<SUP>15</SUP>N ≈ 200-450 is estimated. This range of values is much higher then previously reported on a tentative basis. Therefore, because <SUP>15</SUP>N is less abundant than expected, the question for strong <SUP>15</SUP>N enrichment by massive star ejecta in starbursts still remains to be settled. | en_US |
dc.language.iso | eng | en_US |
dc.title | Molecular line emission in NGC 4945, imaged with ALMA | en_US |
dc.type | Article | - |
dc.identifier.doi | 10.1051/0004-6361/201732174 | en_US |
dc.identifier.scopus | 2-s2.0-85054732559 | en_US |
dc.identifier.isi | 000440418800004 | en_US |
dc.identifier.url | https://www.aanda.org/articles/aa/abs/2018/07/aa32174-17/aa32174-17.html | en_US |
dc.relation.medium | STAMPA | en_US |
dc.relation.volume | 615 | en_US |
dc.relation.firstpage | A155 | en_US |
dc.type.referee | REF_1 | en_US |
dc.description.numberofauthors | 34 | en_US |
dc.description.international | sì | en_US |
dc.contributor.country | DEU | en_US |
dc.relation.scientificsector | FIS/05 - ASTRONOMIA E ASTROFISICA | en_US |
dc.relation.journal | ASTRONOMY & ASTROPHYSICS | en_US |
dc.type.miur | 262 Articolo in rivista | - |
dc.identifier.adsbibcode | 2018A&A...615A.155H | en_US |
dc.relation.ercsector | ERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation | en_US |
dc.description.apc | no | en_US |
dc.description.oa | 1 – prodotto con file in versione Open Access (allegare il file al passo 5-Carica) | en_US |
item.openairecristype | http://purl.org/coar/resource_type/c_18cf | - |
item.openairetype | Article | - |
item.languageiso639-1 | en | - |
item.cerifentitytype | Publications | - |
item.grantfulltext | open | - |
item.fulltext | With Fulltext | - |
crisitem.author.dept | O.A. Arcetri | - |
crisitem.author.orcid | 0000-0001-9162-2371 | - |
crisitem.journal.journalissn | 0004-6361 | - |
crisitem.journal.ance | E016240 | - |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
2018A+A.615.A155Henkel.pdf | Pdf editoriale | 30.51 MB | Adobe PDF | View/Open |
aa32174-17-compr_P01.pdf | Miur | 9 MB | Adobe PDF | |
aa32174-17-compr_P02.pdf | Miur | 7.51 MB | Adobe PDF |
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