Limits on the star formation rates of z>2 damped Ly-alpha systems from H-alpha spectroscopy
Limits on the star formation rates of z>2 damped Ly-alpha systems from H-alpha spectroscopy
复制标题
H-α 光谱对 z>2 阻尼 Ly-α 系统恒星形成速率的限制
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
P. Hewett
中科院分区：
文献类型：
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作者：
A. Bunker;S. Warren;D. Clements;G. Williger;P. Hewett
我们提出了一个长缝K带光谱搜索的结果与CGS 4的UKIRT的H-α发射的对象负责高红移（z>2）阻尼Ly-alpha吸收系统。目的是测量这些系统中的恒星形成率。然而，在我们的3 σ极限f<10 E-19 W/m**2以上没有检测到H-α发射，对应于星星形成速率<10 M_sun/yr/h**2（q_0=0.5）。这些上限比Ly-alpha发射的搜索更有意义，因为H-alpha线不受共振散射的影响。对于q_0=0.5，我们的极限与假设高z DLAs是今天大质量螺旋星系的完全形成的星系盘对应物的条件下预测的星星形成率相冲突。需要更深入的光谱学来检验q_0=0.0时的这幅图。目前正在进行的NICMOS成像观测计划，结合VLT光谱学，将提供DLAs和年轻星系之间联系的详细图片。
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.