Title: Broadband distortion modeling in Lyman-α forest BAO fitting

Abstract

Recently, the Lyman-α absorption observed in the spectra of high-redshift quasars has been used as a tracer of large-scale structure by means of the three-dimensional Lyman-α forest auto-correlation function at redshift z≃ 2.3, but the need to fit the quasar continuum in every absorption spectrum introduces a broadband distortion that is difficult to correct and causes a systematic error for measuring any broadband properties. Here, we describe a k-space model for this broadband distortion based on a multiplicative correction to the power spectrum of the transmitted flux fraction that suppresses power on scales corresponding to the typical length of a Lyman-α forest spectrum. In implementing the distortion model in fits for the baryon acoustic oscillation (BAO) peak position in the Lyman-α forest auto-correlation, we find that the fitting method recovers the input values of the linear bias parameter b_F and the redshift-space distortion parameter β_F for mock data sets with a systematic error of less than 0.5%. Applied to the auto-correlation measured for BOSS Data Release 11, our method improves on the previous treatment of broadband distortions in BAO fitting by providing a better fit to the data using fewer parameters and reducing the statistical errors on βF and themore » combination b_F(1+β_F) by more than a factor of seven. The measured values at redshift z=2.3 are βF=1.39^{+0.11 +0.24 +0.38}_{-0.10 -0.19 -0.28} and bF(1+βF)=-0.374^{+0.007 +0.013 +0.020}_{-0.007 -0.014 -0.022} (1σ, 2σ and 3σ statistical errors). Our fitting software and the input files needed to reproduce our main results are publicly available.« less

Authors:

Blomqvist, Michael ^[1]; Kirkby, David ^[1]; Bautista, Julian E. ^[2]; Arinyo-i-Prats, Andreu ^[3]; Busca, Nicolás G. ^[4]; Miralda-Escudé, Jordi ^[5]; Slosar, Anže ^[6]; Font-Ribera, Andreu ^[7]; Margala, Daniel ^[1]; Schneider, Donald P. ^[8]; Vazquez, Jose A. ^[6]

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+ Show Author Affiliations

1. Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy
2. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Physics and Astronomy
3. Univ. of Barcelona, Catalonia (Spain). Inst. of Cosmos Sciences
4. Univ. of Paris Diderot (France). AstroParticle and Cosmology (APC); National Observatory, Rio de Janeiro (Brazil); Interinstitutional Lab of Astronomy, Rio de Janeiro (Brazil)
5. Catalan Institution for Research and Advanced Studies (ICREA), Barcelona (Spain); Univ. of Barcelona, Catalonia (Spain). Inst. of Cosmos Sciences
6. Brookhaven National Lab. (BNL), Upton, NY (United States)
7. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
8. Pennsylvania State Univ., University Park, PA (United States). Dept. of Astronomy and Astrophysics and Inst. for Gravitation and the Cosmos

Publication Date:

Mon Nov 23 00:00:00 EST 2015

Research Org.:

Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP)

OSTI Identifier:

1335391

Report Number(s):

BNL-111802-2016-JA
Journal ID: ISSN 1475-7516; KA2301020

Grant/Contract Number:  

SC00112704

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Cosmology and Astroparticle Physics

Additional Journal Information:

Journal Volume: 2015; Journal Issue: 11; Journal ID: ISSN 1475-7516

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; dark energy experiments; Lyman alpha forest; cosmological parameters from LSS; baryon acoustic oscillations