We present a theoretical estimate for a new observable: the cross-correlation between the Lyman-alpha flux fluctuations in quasar (QSO) spectra and the convergence of the cosmic microwave background (CMB) as measured along the same line-of-sight. As a first step toward the assessment of its detectability, we estimate the signal-to-noise ratio using linear theory. Although the signal-to-noise is small for a single line-of-sight and peaks at somewhat smaller redshifts than those probed by the Lyman-alpha forest, we estimate a total signal-to-noise of 9 for cross-correlating QSO spectra of SDSS-III with Planck and of 20 for cross-correlating with a future polarization based CMB experiment. The detection of this effect would be a direct measure of the neutral hydrogen-matter cross-correlation and could provide important information on the growth of structures at large scales in a redshift range which is still poorly probed by observations.
|Titolo:||Lenses in the forest: Cross correlation of the lyman-α flux with cosmic microwave background lensing|
|Autori:||Vallinotto, A.; Das, S.; Spergel, D. N.; Viel, Matteo|
|Data di pubblicazione:||2009|
|Numero di Articolo:||091304|
|Digital Object Identifier (DOI):||10.1103/PhysRevLett.103.091304|
|Appare nelle tipologie:||1.1 Journal article|