AAS 195th Meeting, January 2000
Session 14. Early Universe and Cosmology
Display, Wednesday, January 12, 2000, 9:20am-6:30pm, Grand Hall

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[14.03] An Optical/Near-IR Study of a z=4 Lensed Galaxy

A. Bunker (U.C. Berkeley & IoA Cambridge), L. Moustakas (Oxford, U.K.), M. Davis (U.C. Berkeley)

We present deep near-infrared Keck/NIRC imaging of a recently-discovered z=4.04 galaxy (Frye & Broadhurst 1998). This is lensed by the rich foreground cluster Abell 2390 (z\approx 0.23) into highly-magnified arcs 3--5\arcsec\ in length. Our H- and K'-band NIRC imaging allows us to map the Balmer +4000Å\ break amplitude. In combination with high-quality archival HST/WFPC2 data, we can spatially resolve stellar populations along the arcs. The WFPC2 images clearly reveal several bright knots, which correspond to sites of active star formation. However, there are considerable portions of the arcs are significantly redder, consistent with being observed > 100Myr after star formation has ceased. Keck/LRIS long-slit spectroscopy along the arcs reveals that the Ly-\alpha emission is spatially offset by \approx 1\arcsec\ from the rest-UV continuum regions. We show that this line emission is most probably powered by star formation in neighboring HII regions, and that the z=4 system is unlikely to be an AGN. This work is described in more detail in Bunker, Moustakas & Davis (2000), to appear in volume 531 #1 of the Astrophysical Journal (1 March 2000) -- see astro/ph-9909476.

If you would like more information about this abstract, please follow the link to http://www.ast.cam.ac.uk/~bunker/. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: bunker@ast.cam.ac.uk

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