Background power subtraction in Lyman-alpha forest

Abstract

When measuring the one-dimensional power spectrum of the Ly$\alpha$ forest, it is common to measure the power spectrum in flux fluctuations red-ward of the Ly$\alpha$ emission of quasars and subtract this power from the measurements of the Ly$\alpha$ flux power spectrum. This removes excess power present in the Ly$\alpha$ forest which is believed to be dominated by metal absorption by the low-redshift metals uncorrelated with the neutral hydrogen aborbing in Ly$\alpha$. In this brief report we note that, assuming the contaminants are additive in optical depth, the correction contains a second order term. We estimate the magnitude of this term for two currently published measurements of the 1D Ly$\alpha$ flux power spectrum and show that it is negligible for the current generation of measurements. However, future measurements will have to take this into account when errorbars improve by a factor of two or more.

5 pages, 2 figures; published in Physical Review D (5th of May 2014)

References in corpus (4)

• Baryon Acoustic Oscillations in the Ly-α forest of BOSS quasars
• The DESI Experiment, a whitepaper for Snowmass 2013
• The one-dimensional Ly-alpha forest power spectrum from BOSS
• Detection of Lyβauto-correlations and Lyα-Lyβcross-correlations in BOSS Data Release 9

Cited by in corpus (2)

• The Lyman-alpha forest power spectrum from the XQ-100 Legacy Survey
• Unveiling Dark Matter free-streaming at the smallest scales with high redshift Lyman-alpha forest