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Title

A 22-GHz search for molecular absorption at z similar to 3 with the upgraded ATCA

Author(s)

Curran, Stephen J.;  Murphy, Michael T.;  Webb, J. K.;  Pihlstrom, Ylva M.

Abstract

We report a λ. ≲ 1 cm search for rotational molecular absorption towards quasars, now possible with the upgraded Australia Telescope Compact Array (ATCA). The targets were PKS 0201+113, PKS 0336-017 and Q 0537-286, where known damped Lyman-alpha absorption systems (DLAs) could cause redshifted molecular absorption in the 12-mm band of the telescope. We place 3σ upper limits on any HCO+ 0 → 1 absorption features of <30 mJy per 3.4 km s-1 channel. The non-detections could be attributed to the inherent low metallicities in DLAs leading to generally low H2, and thus HCO+, column densities. In general, the detection of molecular rotational transitions in DLAs could be further hindered by a lower than expected CO-to-H2 conversion ratio, whether due either to photoionization of carbon or to its relative under-abundance at high redshift.

Publication type

Journal article

Source

Monthly Notices of the Royal Astronomical Society, Vol. 340, no. 1 (Mar 2003), pp. 139-142

Publication year

2003

Keyword(s)

Alpha system;  CO;  Continuum galaxies;  Early universe;  Galaxies;  Gravitational lens;  High-redshift;  Hydrogen;  ISM;  Lines;  PKS1830-211;  Quasars;  Quasars absorption lines;  Radio

Publisher

Wiley-Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1046/j.1365-8711.2003.06273.x

Copyright

Copyright © 2003 the authors. Journal compilation copyright © 2003 Royal Astronomical Society. The accepted manuscript of the paper is reproduced here in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.

Full text

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