Distribution of the molecular absorption in front of the quasar B0218+357
arXiv:0704.0978 · doi:10.1051/0004-6361:20077310
Abstract
The line of sight to the quasar B0218+357, one of the most studied lensed systems, intercepts a z=0.68 spiral galaxy, which splits its image into two main components A and B, separated by ca. 0.3'', and gives rise to molecular absorption. Although the main absorption component has been shown to arise in front of image A, it is not established whether some absorption from other velocity components is also occuring in front of image B. To tackle this question, we have observed the HCO+(2-1) absorption line during the commissioning phase of the new very extended configuration of the Plateau de Bure Interferometer, in order to trace the position of the absorption as a function of frequency. Visibility fitting of the self-calibrated data allowed us to achieve position accuracy between ~12 and 80 mas per velocity component. Our results clearly demonstrate that all the different velocity components of the HCO+(2-1) absorption arise in front of the south-west image A of the quasar. We estimate a flux ratio fA/fB = 4.2 (-1.0;+1.8 at 106 GHz.
arXiv commentaccepted for publication in A&A Letter special issue for the new extended configuration of the Plateau de Bure Interferometer
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- Chlorine-bearing molecules in molecular absorbers at intermediate redshifts
- Isotopic ratios at z=0.68 from molecular absorption lines toward B 0218+357
- Formaldehyde Anti-Inversion at z=0.68 in the Gravitational Lens B0218+357
- Redshifted formaldehyde from the gravitational lens B0218+357
- Interstellar Silicate Dust in the z=0.685 Absorber Toward TXS 0218+357
- Using gravitational lensed images to investigate the intrinsic AGN variability
- A sub-ppm upper limit on the cosmological variations of the fine structure constant alpha