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[9.04] Optical-to-IR Photometric Properties of Lyman Break Galaxies in the HDF-North

C. Papovich (JHU), M. Dickinson, H. Ferguson (STScI), NICMOS HDF--N GO Team

We present the photometric properties of Lyman Break Galaxies (LBGs) in the Hubble Deep Field North (HDF--N) using deep seven--band photometry from WFPC2 (UBVI, Williams et al.\ 1996), NICMOS (JH, Dickinson et al.\ 2000), and newly derived K_s--band photometry from ground--based KPNO data (Dickinson 1997; Papovich & Dickinson 2000). For the 27 HDF galaxies with spectroscopic redshifts 2.0 \lesssim z \lesssim 3.5, our photometry spans rest frame wavelengths extending from the Lyman limit through rest--frame \lambda₀ \gtrsim 5000Å. In this poster, we compare the spectral energy distributions (SEDs) of the LBGs to empirical spectral templates from Kinney et al.\ (1996) and Coleman, Wu, & Weedman (1980), and to population synthesis models from Bruzual & Charlot (1996). We consider general constraints on galaxy ages, star formation histories, and extinction. By selection, the LBGs contain strong, blue UV continua. In general, they are well fit by local starburst templates. To fit the SEDs of specific galaxies, most require modest but non--zero reddening. At rest--frame optical wavelengths, many galaxies show evidence for significant contributions from longer lived (A and later) stars, but none appear to be dominated by old (red) stellar populations. In some cases, there may be significant broad band flux contributions from strong nebular emission lines ([\ion{N}{2}]+H\alpha, [\ion{O}{3}]+H\beta, [\ion{O}{2}]). We discuss the implications for the evolutionary history of these galaxies using these empirical results. Support for this work is provided by NASA through grant GO-07817.01-96A.