1997/12/14 by A. J. Bunker, A. Bunker, L. A. Moustakas +14
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9712173
4 pages, 3 encapsulated postscript figures; uses LaTex209 with paspconf.sty & epsf.sty; to appear in "The Young Universe: Galaxy Formation and Evolution at Intermediate and High Redshift" (Rome Observatory, 29 Sept - 3 Oct 1997) eds. S. D'Odorico, A. Fontana and E. Giallongo, A.S.P. Conf. Ser
arxiv created 1997/12/14 · openalex publication_date 1997/12/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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~0.23) into highly-magnified arcs 3-5arcsec in length. Our H- and K'-band NIRC imaging allows us to map the Balmer+4000Ang 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 ~1arcsec 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.