1994A&A...286L...9W -
Astronomy and Astrophysics, volume 286, L9-12 (1994/6-1)
First detection of CO(J=0->1) absorption at cosmological distances (z=0.247).
WIKLIND T. and COMBES F.
Abstract (from CDS):
We report the first detection of CO absorption lines in an intermediate redshift galaxy, at z=0.24671. The backgroung continuum source is the BL Lac object PKS 1413+135, which is likely to be situated in the nucleus of the spiral galaxy hosting the absorbing clouds. At least three CO(J=0->1) components were detected. The lines are very narrow, down to 0.6km/s. The filling factor of the absorbing clouds is large (≳80%). The extent of the continuum source is unknown. VLBI cm data suggests a size of several parsecs, whereas rapid variability suggests a size of ∼103 AU. Since the filling factor and optical depth cannot be determined independently, we can only derive a lower limit to the column density of CO. In the case of a diffuse component completely covering the background source, the N(CO) column density is 1x10^16 cm–2, but the true values could be much higher. The CO absorption lines change in depth on time scale of a few weeks. We attribute these variations to the superluminal motions of the radio jet in PKS 1413+135 or to proper motion of very small-scale molecular clumps
Abstract Copyright:
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Journal keyword(s):
interstellar medium: molecules - galaxies: PKS 1413+135, ISM, absorption lines, radio continuum
Simbad objects:
3
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