A Narrow-Band Near-Ir Search for - Galaxy Clusters at Z Similar to

December 1997 • 1997PhDT.........2T

Authors • Teplitz, Harry Isaac

Abstract • This dissertation details a search for star-forming galaxies at z/ [_~> 1, using narrow-band near-infrared filters to detect redshifted Hα₊ ^NII emission from objects in fields containing QSOs or absorption-line systems. The observations were obtained at Lick observatory with the UCLA Two-Channel Near-Infrared Camera on the Shane 3 m telescope and at Keck Observatory with the Near Infrared Camera on the 10 m Keck I telescope. A pilot project was first conducted to demonstrate the validity of the observing and data reduction techniques. JHK photometry of the intermediate redshift clusters Abell 370, Cl 0024+1654, Abell 963, and Cl 0909+4408 was obtained. The search for z ~1 Hα-emitting galaxies has revealed two emission-line galaxies with inferred Star Formation Rates of 12.5 and 25.5 M_solaryr^-1. The search also detected several fields containing excess faint galaxies. More than 0.05 degree² were observed with 5σ limiting sensitivities of at least J = 20.5 and K^' = 19. Infrared number counts were prepared and the K^' data were in good agreement with other published results. The J-band number counts are amoung the first to be obtained to this depth. They show less of a faint-end turnover than K-band counts. The z > 2 search has revealed 10-12 Hα-emitting galaxies in small groups, typically within 250kpc of the QSO line of sight; they are resolved but compact, with average SFR = 30M_solar/yr. The search has covered more than 8 square arcminutes. Comparison of the Spectral Energy Distribution for the Hα-emitters with Bruzual and Charlot spectral synthesis models suggest that these galaxies may have formed at redshifts close to z = 5.5. Optical and infrared spectroscopy confirm the redshift of one Hα detection. The high density of Emission Line Galaxy detections suggest that these Hα-emitters may be clustered with the QSOs and absorbers. The two-point correlation function of Hα-emitters in the volume surved is at least ten times that for field galaxies in the present epoch.

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