The Effect of Interstellar Absorption on Measurements of the Baryon Acoustic Peak in the Lyman-α Forest

Abstract

In recent years, the autocorrelation of the hydrogen Lyman-α forest has been used to observe the baryon acoustic peak at redshift 2 < z < 3.5 using tens of thousands of QSO spectra from the BOSS survey. However, the interstellar medium of the Milky-Way introduces absorption lines into the spectrum of any extragalactic source. These lines, while weak and undetectable in a single BOSS spectrum, could potentially bias the cosmological signal. In order to examine this, we generate absorption line maps by stacking over a million spectra of galaxies and QSOs. We find that the systematics introduced are too small to affect the current accuracy of the baryon acoustic peak, but might be relevant to future surveys such as the Dark Energy Spectroscopic Instrument (DESI). We outline a method to account for this with future datasets.

MNRAS accepted. Minor changes

References in corpus (8)

• The DESI Experiment Part I: Science,Targeting, and Survey Design
• Baryon Acoustic Oscillations in the Lyα forest of BOSS DR11 quasars
• Baryon Acoustic Oscillations in the Ly-α forest of BOSS quasars
• The Sloan Digital Sky Survey Quasar Catalog: twelfth data release
• Measurement of BAO correlations at $z=2.3$ with SDSS DR12 \lya-Forests
• Calcium H & K and sodium D absorption induced by the interstellar and circumgalactic media of the Milky Way
• Fine cophasing of segmented aperture telescopes with ZELDA, a Zernike wavefront sensor in the diffraction-limited regime
• Dusting off the diffuse interstellar bands: DIBs and dust in extragalactic SDSS spectra