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Herschel Observations Reveal Anomalous Molecular Abundances toward the Galactic Center

Sonnentrucker, P. and Neufeld, D. A. and Gerin, M. and De Luca, M. and Indriolo, N. and Lis, D. C. and Goicoechea, J. R. (2013) Herschel Observations Reveal Anomalous Molecular Abundances toward the Galactic Center. Astrophysical Journal Letters, 763 (1). Art. No. L19. ISSN 2041-8205. doi:10.1088/2041-8205/763/1/L19. https://resolver.caltech.edu/CaltechAUTHORS:20130215-113506607

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Abstract

We report the Herschel detections of hydrogen fluoride (HF) and para-water (p-H_(2)O) in gas intercepting the sight lines to two well-studied molecular clouds in the vicinity of the Sgr A complex: G–0.02–0.07 (the "+50 km s^(–1) cloud") and G–0.13–0.08 (the "+20 km s^(–1) cloud"). Toward both sight lines, HF and water absorption components are detected over a wide range of velocities covering ~250 km s^(–1). For all velocity components with V_LSR > –85 km s^(–1), we find that the HF and water abundances are consistent with those measured toward other sight lines probing the Galactic disk gas. The velocity components with V LSR ≤ –85 km s^(–1), which are known to trace gas residing within ~200 pc of the Galactic center, however, exhibit water vapor abundances with respect to HF at least a factor three higher than those found in the Galactic disk gas. Comparison with CH data indicates that our observations are consistent with a picture where HF and a fraction of the H_(2)O absorption arise in diffuse molecular clouds showing Galactic disk-like abundances while the bulk of the water absorption arises in warmer (T ≥ 400 K) diffuse molecular gas for V LSR ≤ –85 km s^(–1). This diffuse Interstellar Medium (ISM) phase has also been recently revealed through observations of CO, HF, H^(+)_3, and H_(3)O^+ absorption toward other sight lines probing the Galactic center inner region.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/2041-8205/763/1/L19DOIArticle
http://iopscience.iop.org/2041-8205/763/1/L19PublisherArticle
ORCID:
AuthorORCID
Neufeld, D. A.0000-0001-8341-1646
Indriolo, N.0000-0001-8533-6440
Lis, D. C.0000-0002-0500-4700
Additional Information:© 2013 American Astronomical Society. Received 2012 September 4; accepted 2012 December 11; published 2013 January 7. We wish to thank R. G¨usten and M. Requena-Torres for extracting and sharing Herschel/HEXGAL data allowing us to determine that the OFF-beam position in our HIFI observations of p-H2O and HF does not suffer from contamination due to the presence of extended emission/absorption around the Galactic center. We wish to thank our referee whose comments improved our work significantly. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada, and the United States under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands, and with major contributions from Germany, France, and USA. Consortium members are: Canada: CSA, U. Waterloo; France: CESR, LAB, LERMA, IRAM; Germany: KOSMA, MPIfR, MPS; Ireland, NUI Maynooth; Italy: ASI, IFSI-INAF, Osservatorio Astrofisico di Arcetri-INAF; Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astron´omico Nacional (IGN), Centro de Astrobiolog´ıa (CSIC/INTA); Sweden: Chalmers University of Technology- MC2, RSS & GARD, Onsala Space Observatory, Swedish National Space Board, Stockholm University-Stockholm Observatory; Switzerland: ETH Zurich, FHNW; USA: Caltech, JPL, NHSC. M.S. acknowledges support from grant N 203 393334 from Polish MNiSW. Support for this work was provided to M. De Luca and M. Gerin by the Centre National de Recherche Spatiale (CNES) and by the SCHISM project (grant ANR-09-BLAN-0231-01). J.R.G. is supported by a Ram´on y Cajal research contract and thanks the Spanish MINECO for funding support through grants AYA2009-07304 and CSD2009-00038. Support for this work was provided by NASA through an award issued by JPL/Caltech. Facility: Herschel
Funders:
Funding AgencyGrant Number
Ministerstwo Nauki i Szkolnictwa Wyższego (MNiSW)N 203 393334
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Agence Nationale pour la Recherche (ANR)ANR-09- BLAN-0231-01
Ramón y Cajal ProgrammeUNSPECIFIED
Ministerio de Economía, Industria y Competitividad (MINECO)AYA2009-07304
Ministerio de Economía, Industria y Competitividad (MINECO)CSD2009-00038
NASA/JPL/CaltechUNSPECIFIED
Subject Keywords:ISM: individual objects (G, 0.02, 0.07, G, 0.13, 0.08); ISM: lines and bands; ISM: molecules
Issue or Number:1
DOI:10.1088/2041-8205/763/1/L19
Record Number:CaltechAUTHORS:20130215-113506607
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130215-113506607
Official Citation:Herschel Observations Reveal Anomalous Molecular Abundances toward the Galactic Center P. Sonnentrucker et al. 2013 ApJ 763 L19
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36959
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:19 Feb 2013 18:50
Last Modified:09 Nov 2021 23:25

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