期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 738, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/2041-8205/738/1/L6
关键词
cosmology: observations; galaxies: active; galaxies: high-redshift; galaxies: individual (APM 08279+5255); ISM: molecules
资金
- INSU/CNRS (France)
- MPG (Germany)
- IGN (Spain)
- NASA
- NSF [AST-0540882]
We report a detection of the excited 2(20)-2(11) rotational transition of para-H2O in APM 08279+5255 using the IRAM Plateau de Bure Interferometer. At z = 3.91, this is the highest-redshift detection of interstellar water to date. From large velocity gradient modeling, we conclude that this transition is predominantly radiatively pumped and on its own does not provide a good estimate of the water abundance. However, additional water transitions are predicted to be detectable in this source, which would lead to an improved excitation model. We also present a sensitive upper limit for the hydrogen fluoride (HF) J = 1-0 absorption toward APM 08279+5255. While the face-on geometry of this source is not favorable for absorption studies, the lack of HF absorption is still puzzling and may be indicative of a lower fluorine abundance at z = 3.91 compared with the Galactic interstellar medium.
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