Sökning: WFRF:(Costagliola Francesco 1981) >
H3O+ line emission ...
H3O+ line emission from starbursts and AGNs
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- Aalto, Susanne, 1964 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Costagliola, Francesco, 1981 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- van der Tak, F. F. S. (författare)
- Rijksuniversiteit Groningen,University of Groningen
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- Meijerink, R. (författare)
- Universiteit Leiden (UL),Leiden University (UL)
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(creator_code:org_t)
- 2011-01-26
- 2011
- Engelska.
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 527:8
- Relaterad länk:
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http://publications.... (primary) (free)
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https://www.aanda.or...
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https://research.cha...
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https://research.cha...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Context. The H3O+ molecule probes the chemistry and the ionization rate of dense circumnuclear gas in galaxies. Aims. We use the H3O+ molecule to investigate the impact of starburst and AGN activity on the chemistry of the molecular interstellar medium. Methods. Using the JCMT, we have observed the 3(2)(+)-2(2)(-) 364 GHz line of p-H3O+ towards the centres of seven active galaxies. Results. We have detected p-H3O+ towards IC 342, NGC 253, NGC 1068, NGC 4418, and NGC 6240. Upper limits were obtained for IRAS 15250 and Arp 299. We find large H3O+ abundances (N(H3O+)/N(H-2) greater than or similar to 10(-8)) in all detected galaxies apart from in IC 342 where it is about one order of magnitude lower. We note, however, that uncertainties in N(H3O+) may be significant due to lack of definite information on source size and excitation. We furthermore compare the derived N(H3O+) with N(HCO+) and find that the H3O+ to HCO+ column density ratio is large in NGC 1068 ( 24), moderate in NGC 4418 and NGC 253 ( 4-5), slightly less than unity in NGC 6240 ( 0.7) and lowest in IC 342 ( 0.2-0.6). We compare our results with models of X-ray and photon dominated regions ( XDRs and PDRs). Conclusions. For IC 342 we find that a starburst PDR chemistry can explain the observed H3O+ abundance. For the other galaxies, the large H3O+ columns are generally consistent with XDR models. In particular for NGC 1068 the elevated N(H3O+)/N(HCO+) ratio suggests a low column density XDR. For NGC 4418 however, large HC3N abundances are inconsistent with the XDR interpretation. An alternative possibility is that H3O+ forms through H2O evaporating off dust grains and reacting with HCO+ in warm, dense gas. This scenario could also potentially fit the results for NGC 253. Further studies of the excitation and distribution of H3O+-aswell as Herschel observations of water abundances - will help to further constrain the models.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- nucleus
- ultraluminous infrared galaxies
- dense molecular gas
- galaxies: evolution
- young stellar objects
- ngc 1068
- active galactic
- ISM: molecules
- star-formation
- nearby galaxies
- galaxies: active
- high-spatial-resolution
- ic 342
- galaxies: starburst
- radio
- x-ray
- lines: galaxies
Publikations- och innehållstyp
- art (ämneskategori)
- ref (ämneskategori)
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