Lenses in the forest: cross--correlation of the Lyman-alpha flux with CMB lensing
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 SDSSIII with Planck and 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.
- Research Organization:
- Fermi National Accelerator Laboratory (FNAL), Batavia, IL
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 950875
- Report Number(s):
- FERMILAB-PUB-09-084-A; arXiv eprint number arXiv:0903.4171
- Journal Information:
- Submitted to Phys.Rev.Lett., Journal Name: Submitted to Phys.Rev.Lett. Journal Issue: 9 Vol. 103; ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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