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Limits on the star formation rates of z>2 damped Ly-alpha systems from H-alpha spectroscopy

Andrew J. Bunker·Stephen J. Warren·D. L. Clements·Gerard M. Williger·P. C. Hewett
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Abstract

We present the results of a long-slit K-band spectroscopic search with CGS4 on UKIRT for H-alpha emission from the objects responsible for high-redshift (z > 2) damped Ly-alpha absorption systems. The objective was to measure the star-formation rates in these systems. However, no H-alpha emission was detected above our 3-sigma limits of f < 10E-19 W/m**2, corresponding to star formation rates < 10 M_sun/yr/h**2 (q_0=0.5). These upper limits are more meaningful than those from searches for Ly-alpha emission because the H-alpha line is unaffected by resonant scattering. For q_0=0.5 our limits are in conflict with the star formation rates predicted under the assumption that the high-z DLAs are the fully-formed galactic-disk counterparts of today's massive spiral galaxies. Deeper spectroscopy is needed to test this picture for q_0=0.0. A programme of NICMOS imaging observations currently underway, combined with VLT spectroscopy, will provide a detailed picture of the link between DLAs and young galaxies.

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Andrew J. Bunker, Stephen J. Warren, D. L. Clements, Gerard M. Williger, P. C. Hewett. 1998-06-15. Limits on the star formation rates of z>2 damped Ly-alpha systems from H-alpha spectroscopy. https://arxiv.org/abs/astro-ph/9806208

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