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SUBMILLIMETER-HCN D...
SUBMILLIMETER-HCN DIAGRAM FOR ENERGY DIAGNOSTICS IN THE CENTERS OF GALAXIES
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- Izumi, T. (author)
- University of Tokyo, Japan
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- Kohno, K. (author)
- University of Tokyo, Japan
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- Aalto, Susanne, 1964 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Espada, D. (author)
- National Astronomical Observatory of Japan,The Graduate University for Advanced Studies (SOKENDAI),Atacama Large Millimeter-submillimeter Array (ALMA)
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Fathi, K. (author)
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- Harada, N. (author)
- Academia Sinica Taiwan
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- Hatsukade, B. (author)
- National Astronomical Observatory of Japan
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- Hsieh, P. Y. (author)
- Academia Sinica Taiwan,National Central University
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- Imanishi, M. (author)
- National Astronomical Observatory of Japan,The Graduate University for Advanced Studies (SOKENDAI)
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- Krips, M. (author)
- Institut de Radioastronomie Millimétrique (IRAM)
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- Martin, S. (author)
- European Southern Observatory Santiago,Atacama Large Millimeter-submillimeter Array (ALMA),Institut de Radioastronomie Millimétrique (IRAM)
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- Matsushita, S. (author)
- Academia Sinica Taiwan
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- Meier, D. S. (author)
- New Mexico Institute of Mining and Technology
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- Nakai, N. (author)
- University of Tsukuba
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- Nakanishi, K. (author)
- National Astronomical Observatory of Japan,The Graduate University for Advanced Studies (SOKENDAI),Atacama Large Millimeter-submillimeter Array (ALMA)
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- Schinnerer, E. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Sheth, K. (author)
- National Aeronautics and Space Administration (NASA)
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- Terashima, Y. (author)
- Ehime University
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- Turner, J. L. (author)
- University of California
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(creator_code:org_t)
- 2016-02-05
- 2016
- English.
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In: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 818:1
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Abstract
Subject headings
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- Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4-3)/HCO+(4-3) and/or HCN(4-3)/CS(7-6) integrated intensity ratios in circumnuclear molecular gas around active galactic nuclei (AGNs) compared to those in starburst (SB) galaxies (submillimeter HCN. enhancement). The number of sample galaxies is significantly increased from our previous work. We expect that this feature could potentially be an extinction-free energy diagnostic tool of nuclear regions of galaxies. Non-LTE radiative transfer modelings of the above molecular emission lines involving both collisional and radiative excitation, as well as a photon trapping effect, were conducted to investigate the cause of the high line ratios in AGNs. As a result, we found that enhanced abundance ratios of HCN to HCO+ and HCN to CS in AGNs as compared to SB galaxies by a factor of a few to even greater than or similar to 10 are a plausible explanation for the submillimeter HCN. enhancement. However, a counterargument of a systematically higher gas density in AGNs than in SB galaxies can also be a plausible scenario. Although we cannot fully distinguish. these two scenarios at this moment owing to an insufficient amount of multi-transition, multi-species data, the former scenario is indicative of abnormal chemical composition in AGNs. Regarding the actual mechanism to realize the composition, we suggest that it is difficult with conventional gas-phase X-ray-dominated region ionization models to reproduce the observed high line ratios. We might have to take into account other mechanisms such as neutral-neutral reactions that are efficiently activated in high-temperature environments and/or mechanically heated regions to further understand the high line ratios in AGNs.
Subject headings
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Keyword
- ISM: molecules
- galaxies: ISM
- galaxies: active
Publication and Content Type
- art (subject category)
- ref (subject category)
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To the university's database
- By the author/editor
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Izumi, T.
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Kohno, K.
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Aalto, Susanne, ...
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Espada, D.
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Fathi, K.
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Harada, N.
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show more...
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Hatsukade, B.
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Hsieh, P. Y.
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Imanishi, M.
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Krips, M.
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Martin, S.
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Matsushita, S.
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Meier, D. S.
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Nakai, N.
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Nakanishi, K.
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Schinnerer, E.
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Sheth, K.
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Terashima, Y.
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Turner, J. L.
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- NATURAL SCIENCES
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NATURAL SCIENCES
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Chalmers University of Technology