Large-scale clustering of Lyman α emission intensity from SDSS/BOSS

Citation:

Croft RAC, Miralda-Escudé J, Zheng Z, Bolton A, Dawson KS, Peterson JB, York DG, Eisenstein D, Brinkmann J, Brownstein J, et al. Large-scale clustering of Lyman α emission intensity from SDSS/BOSS. Monthly Notices of the Royal Astronomical Society. 2016;457 :3541-3572.

Date Published:

April 1, 2016

Abstract:

We present a tentative detection of the large-scale structure of Lyα emission in the Universe at redshifts z = 2-3.5 by measuring thecross-correlation of Ly α surface brightness with quasars in SloanDigital Sky Survey/Baryon Oscillation Spectroscopic Survey. We use amillion spectra targeting luminous red galaxies at z < 0.8, aftersubtracting a best-fitting model galaxy spectrum from each one, as anestimate of the high-redshift Ly α surface brightness. Thequasar-Ly α emission cross-correlation is detected on scales 1˜ 15 h-1 Mpc, with shape consistent with a ΛCDMmodel with Ω _m =0.30^{+0.10}_{-0.07}. The predicted amplitude ofthis cross-correlation is proportional to the product of the mean Lyα surface brightness, <μα>, theamplitude of mass fluctuations and the quasar and Ly α emissionbias factors. We infer <μα>(bα/3) = (3.9 ± 0.9) × 10-21erg s-1 cm-2 Å-1arcsec-2, where bα is the Ly αemission bias. If star-forming galaxies dominate this emission, we findρSFR = (0.28 ± 0.07)(3/bα)yr-1 Mpc-3. For bα = 3, thisvalue is ˜30 times larger than previous estimates fromindividually detected Ly α emitters, but consistent with the totalρSFR derived from dust-corrected, continuum UV galaxysurveys, if most of the Ly α photons from these galaxies avoiddust absorption and are reemitted after diffusing in large gas haloes.Heating of intergalactic gas by He II photoionization from quasarradiation or jets may alternatively explain the detected correlation,and cooling radiation from gas in galactic haloes may also contribute.We also detect redshift space anisotropy of the quasar-Ly αemission cross-correlation, finding evidence at the 3.0σ levelthat it is radially elongated, which may be explained byradiative-transfer effects. Our measurements represent the firstapplication of the intensity mapping technique to optical observations.

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