AAS Meeting #193 - Austin, Texas, January 1999
Session 61. Cosmology/Large Scale Structure I
Oral, Thursday, January 7, 1999, 2:00-3:30pm, Room 9 (A and B)

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[61.04] Seeking the Ultraviolet Ionizing Background at z\approx 3 with the Keck Telescope

A. J. Bunker (Berkeley), F. R. Marleau (IoA Cambridge), J. R. Graham (Berkeley)

We describe an ongoing experiment to search for the metagalactic Lyman-continuum background at z~3. We are obtaining one of the deepest optical spectra ever, using Keck/LRIS to search for 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 (Lyman limit systems).

Our preliminary study (Bunker, Marleau & Graham 1998, astro-ph/808111) placed a 3\sigma upper bound on the mean intensity of the ionizing background at the Lyman limit of J\nu0 < 2\times 10-21~erg~s-1~cm-2~Hz-1~sr-1 for 2.70=0.5, H0=50~km~s-1~Mpc-1). This constraint is an order of magnitude more stringent than any previously published direct limit. We have recently increased our integration time by a factor of ten.

We will describe how the results of this study can be used to constrain the quasar luminosity function and the contribution of high-redshift star forming galaxies to the ambient ionizing background. We also show that it is unlikely that decaying relic neutrinos, if comprising the bulk of the dark matter, are responsible for the meta-galactic radiation field.

If you would like more information about this abstract, please follow the link to http://astro.berkeley.edu/~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@bigz.Berkeley.EDU

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