| 1. |
- König, Sabine, 1983, et al.
(författare)
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Subarcsecond imaging of the water emission in Arp 220
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 602, s. 42-
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Tidskriftsartikel (refereegranskat)abstract
- Aims. Extragalactic observations of water emission can provide valuable insight into the excitation of the interstellar medium. In particular they allow us to investigate the excitation mechanisms in obscured nuclei, that is, whether an active galactic nucleus or a starburst dominates.Methods. We use subarcsecond resolution observations to tackle the nature of the water emission in Arp 220. ALMA Band 5 science verification observations of the 183 GHz H2O 313 − 220 line, in conjunction with new ALMA Band 7 H2O 515 − 422 data at 325 GHz, and supplementary 22 GHz H2O 616 − 523 VLA observations, are used to better constrain the parameter space in the excitation modeling of the water lines.Results. We detect 183 GHz H2O and 325 GHz water emission toward the two compact nuclei at the center of Arp 220, being brighter in Arp 220 West. The emission at these two frequencies is compared to previous single-dish data and does not show evidence of variability. The 183 and 325 GHz lines show similar spectra and kinematics, but the 22 GHz profile is significantly different in both nuclei due to a blend with an NH3 absorption line.Conclusions. Our findings suggest that the most likely scenario to cause the observed water emission in Arp 220 is a large number of independent masers originating from numerous star-forming regions.
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| 2. |
- Ott, Jürgen, et al.
(författare)
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Cm and mm Survey of Molecular Absorption Lines in Centaurus A
- 2012
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Ingår i: American Astronomical Society, AAS Meeting. ; 219, s. 349.26-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present Australia Telescope Array data of molecular absorption lines toward the bright central core of Centaurus A. The line of sight crosses the prominent dust lane and continues through the disk and eventually through gas that may be very close to the central supermassive black hole. The goal of our the survey is to determine the physical conditions of the gas via analyses of molecular line tracers including molecular abundances and excitation that is sensitive to changes in temperature, density, ionization, and shocks. This study allows us to derive the physical conditions of every absorption line complex and finally let us assign the most likely environments. We present ATCA data in the 20-50GHz range at medium resolution of a few km/s and possibly ALMA data at 3mm and 1mm wavelengths. The project continues with sub-km/s higher spectral resolution for the most important lines in 2012.
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