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Session 112 - Galaxy Surveys.
Oral session, Thursday, January 16
We present the preliminary results of a narrow-band IR survey of QSO and metal absorption-line fields for redshifted H\alpha/[NII] emission from starforming galaxies at z\ge 1. As we reported in BAAS 188.21.02 this survey has already lead to the discovery of several possible clusters.
To date, in fields targetted for objects at z>2, we have observed more than 8 sqaure arcminutes using 1% filters in the Near IR Camera on the Keck 10m telescope. The observations reach a limiting magnitude of K=22, and would detect a limiting H\alpha flux of 3\times 10^-17 ergs/s/cm^2 (H_0=50, q_0=0.5). In these fields we have detected 10--12 H\alpha candidates, down to an inferred continuum luminosity of L* or below. In all but one object, the detections have been in fields containing metal-absorption line systems. The detected objects have shown compact, but resolved morphologies, not exceeding FWHM=1^\prime \prime (8kpc). The inferred Star Formation Rate of objects is typically 20 M_ødot/year, but some objects exceed 100 M_ødot/year. Spectroscopic followup with the Low Resolution Imaging Spectrometer has confirmed the redshift of our first detection. The high surface density of detections (\sim 1.5/sq.arcminute) and high SFR suggests clustering in fields containing metal-absorption line systems.
In fields targetted to z\sim 1, we have surveyed 50 square arcmintues down to limiting magnitude of K=19, using the UCLA 2-channel IR Camera on the Shane 3m telescope at Lick Observatory. To date, few emission line galaxies have been detected. In some fields a 2--3\sigma excess of galaxies is observed.
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