%0 Journal Article %J Physical Review D %D 2007 %T Dark energy and curvature from a future baryonic acoustic oscillation survey using the Lyman-α forest %A McDonald, Patrick %A Eisenstein, Daniel J. %X

We explore the requirements for a Lyman-α forest survey designedto measure the angular diameter distance and Hubble parameter at2≲z≲4 using the standard ruler provided by baryonic acousticoscillations (BAO). The goal would be to obtain a high enough density ofsources to probe the three-dimensional density field on the scale of theBAO feature. A percent-level measurement in this redshift range canalmost double the Dark Energy Task Force figure of merit, relative tothe case with only a similar precision measurement at z˜1, if theUniverse is not assumed to be flat. This improvement is greater than theone obtained by doubling the size of the z˜1 survey, with Planckand a weak Sloan Digital Sky Survey-like z=0.3 BAO measurement assumedin each case. Galaxy BAO surveys at z˜1 may be able to make aneffective Lyα forest measurement simultaneously at minimal addedcost, because the required number density of quasars is relativelysmall. We discuss the constraining power as a function of area,magnitude limit (density of quasars), resolution, and signal-to-noise ofthe spectra. For example, a survey covering 2000 sq. deg. and achievingS/N=1.8 per Å at g=23 (˜40quasars per sq. deg.) with anR≳250 spectrograph is sufficient to measure both the radial and

%B Physical Review D %V 76 %P 63009 %8 September 1, 200 %G eng %U http://adsabs.harvard.edu/abs/2007PhRvD..76f3009M %3 eprintid: arXiv:astro-ph/0607122