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CO, HCO and HCN absorption in the gravitational lens candidate B0218+357 at z=0.685

T. Wiklind, F. Combes
Onsala Space Observatory, S--43992 Onsala, Sweden
DEMIRM, Observatoire de Paris, 61 Av. de l'Observatoire, F--75014 Paris, France
Abstract: Absorption lines of CO(1--2), CO(2--3), HCO(1--2) and HCN(1--2) have been detected at a redshift of towards the background BLLac object B0218+357. The CO and HCN lines are strongly saturated, while the HCO line is mildly saturated (Fig 5). Lower limits to the column densities are cm for CO, cm for HCO and cm for HCN. The filling factor for the background source is larger than 0.7--0.8. The absorption line profile is asymmetric with a width of kms . B0218+357 is a gravitational lens candidate with two compact continuum sources separated by 335mas (1.8kpc). The small linewidth of the molecular absorption puts constraints on the inclination and position angle of the lensing galaxy. We also report a search for QSOs molecular absorption lines in 12 other redshifted systems; none were detected.

Figure: Low resolution spectra of a) HCN (J=1-2), kms , and b) HCO, kms , towards B0218+357. The velocity scale in heliocentric and centered at

Robert Lucas
Thu Mar 9 12:14:01 MET 1995