Seeking the Ultraviolet Ionizing Background at z~3 with the Keck Telescope

Abstract

We describe the initial results of a deep long-slit emission line search for redshifted (2.7<z<4.1) Lyman-alpha. These observations are used to constrain the fluorescent Ly-alpha emission from the population of clouds whose absorption produces the higher-column-density component of the Ly-alpha forest in quasar spectra. We use the results to set an upper limit on the ultraviolet ionizing background. Our spectroscopic data obtained with the Keck II telescope at lambda/(Delta lambda FWHM)~2000 reveals no candidate Ly-alpha emission over the wavelength range of 4500-6200 Ang along a 3 arcmin slit in a 5400 s integration. Our 3 sigma upper bound on the mean intensity of the ionizing background at the Lyman limit is J(nu 0) < 2E-21 erg/s/cm**2/Hz/sr for 2.7<z<3.1 (where we are most sensitive), assuming Lyman limit systems have typical radii of 70 kpc (q_0=0.5, H_0=50 km/s/Mpc). This constraint is more than an order of magnitude more stringent than any previously published direct limit. However, it is still a factor of three above the ultraviolet background level expected due to the integrated light of known quasars at z~3. This pilot study confirms the conclusion of Gould \& Weinberg (1996) that integrations of several hours on a 10-m class telescope should be capable of measuring J(nu 0) at high redshift.

22 pages, 2 postscipt figures. Latex requires aaspp4.sty and epsf.sty (included). Accepted for publication in the Astronomical Journal (Nov 1998)

References in corpus (4)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Evidence for oscillation of atmospheric neutrinos
• Unveiling Dust-enshrouded Star Formation in the Early Universe: a Sub-mm Survey of the Hubble Deep Field
• HST Images of a Galaxy Group at z=2.81, and the Sizes of Damped Lyman Alpha Galaxies

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