A NARROW-BAND IMAGING SURVEY FOR HIGH-REDSHIFT GALAXIES IN THE NEAR-INFRARED

A narrowband imaging survey of 276 square minutes of are was carried o ut at near-infrared wavelengths to search for emission line objects at high redshifts. Most of the fields contained a known quasar or radio galaxy at a redshift that placed one of the strong, restframe optical emission lines (H alpha, [O III], H beta, or [O II]) in the bandpass o f the narrowband filter. The area weighted line flux limit over the en tire survey was 3.4 x 10(-16) erg cm(-2) s(-1) (3 sigma), while the mo st sensitive limits reached 1.4 x 10(-16) erg cm(-2) s(-1) Integrating the volume covered by all four optical emission lines in each image y ields a total comoving volume surveyed of 1.4 x 10(5) Mpc(3). Consider ing only H alpha emission in the K band (2.05<(z-)<2.65), where the su rvey is most sensitive, the survey covered a comoving volume of 3.0 x 10(4) Mpc(3) to a volume-weighted average star formation rate of 112 M . yr(-1) (for H-0 = 50 km s(-1) Mpc(-1), Omega(0) = 1). This is the mo st extensive near-infrared survey which is deep enough to have a reaso nable chance at detecting strong line emission from an actively star-f orming population of galaxies, when measured against simple models of galaxy formation. One emission line candidate was identified in this s urvey, and subsequently confirmed spectroscopically. (C) 1996 American Astronomical Society.