Journal
ASTROPHYSICAL JOURNAL
Volume 546, Issue 2, Pages 665-671Publisher
IOP PUBLISHING LTD
DOI: 10.1086/318323
Keywords
galaxies : distances and redshifts; galaxies : formation; intergalactic medium; large-scale structure of universe
Categories
Ask authors/readers for more resources
We report the detection of significant Lyman-continuum flux in the composite spectrum of 29 Lyman-break galaxies (LBGs) with redshifts [z] = 3.40 +/- 0.09. After correction for opacity due to intervening absorption using a new composite QSO spectrum evaluated at the same redshift, the ratio of emergent flux density at 1500 Angstrom in the rest frame to that in the Lyman continuum is L (1500)/L (900) = 4.6 +/- 1.0. If the relative intensity of the inferred escaping Lyman-continuum radiation is typical of LBGs at z similar to 3 (the galaxies in this sample are drawn from the bluest quartile of LBG spectral energy distributions due to known selection effects), then observed LBGs produce about 5 times more H-ionizing photons per unit comoving volume than QSOs at z similar to 3. The associated contribution to the metagalactic ionizing radiation field is J(v)(912 Angstrom) approximate to 1.2 +/- 0.3 x 10(-21) ergs s(-1) cm(-2) Hz(-1) sr(-1) at z similar to3, very close to most estimates of the radiation field background based on the proximity effect. A preliminary analysis of the density of faint QSOs in our Lyman-break galaxy survey indicates that the standard extrapolated QSO luminosity function may slightly overpredict the QSO contribution to J(v)(912) ata z similar to3. We briefly discuss the implications of a galaxy-dominated UV background at high redshifts.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available