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Title: How to estimate the 3D power spectrum of the Lyman-α forest

Journal Article · · Journal of Cosmology and Astroparticle Physics
 [1];  [2];  [3]
  1. Univ. College London, Bloomsbury (United Kingdom). Dept. of Physics and Astronomy
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
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We derive and numerically implement an algorithm for estimating the 3D power spectrum of the Lyman-α (Lyα) forest flux fluctuations. The algorithm exploits the unique geometry of Lyα forest data to efficiently measure the cross-spectrum between lines of sight as a function of parallel wavenumber, transverse separation and redshift. We start by approximating the global covariance matrix as block-diagonal, where only pixels from the same spectrum are correlated. We then compute the eigenvectors of the derivative of the signal covariance with respect to cross-spectrum parameters, and project the inverse-covariance-weighted spectra onto them. This acts much like a radial Fourier transform over redshift windows. The resulting cross-spectrum inference is then converted into our final product, an approximation of the likelihood for the 3D power spectrum expressed as second order Taylor expansion around a fiducial model. We demonstrate the accuracy and scalability of the algorithm and comment on possible extensions. Our algorithm will allow efficient analysis of the upcoming Dark Energy Spectroscopic Instrument dataset.

Research Organization:
Brookhaven National Laboratory (BNL), Upton, NY (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP); Univ. College London, Bloomsbury (United Kingdom)
Grant/Contract Number:
SC0012704; ST/N003853/1; AC02-05CH11231
OSTI ID:
1424960
Alternate ID(s):
OSTI ID: 1530316
Report Number(s):
BNL-200052-2018-JAAM; TRN: US1801980
Journal Information:
Journal of Cosmology and Astroparticle Physics, Vol. 2018, Issue 01; ISSN 1475-7516
Publisher:
Institute of Physics (IOP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 11 works
Citation information provided by
Web of Science

References (13)

Power-spectrum analysis of three-dimensional redshift surveys journal May 1994
Cosmological constraints from the SDSS luminous red galaxies journal December 2006
The one-dimensional Ly α forest power spectrum from BOSS journal November 2013
Baryon acoustic oscillations in the Ly α forest of BOSS quasars journal April 2013
Baryon acoustic oscillations in the Ly α forest of BOSS DR11 quasars journal January 2015
Measurement of baryon acoustic oscillation correlations at z  = 2.3 with SDSS DR12 Ly α -Forests journal June 2017
A maximum likelihood analysis of the low cosmic microwave background multipoles from the Wilkinson Microwave Anisotropy Probe journal March 2004
An evolution free test for non-zero cosmological constant journal October 1979
Cosmic microwave background anisotropy window functions revisited journal October 1999
High-performance P3M N-body code: CUBEP3M journal September 2013
Mining weak lensing surveys journal August 2003
Mass-loss on the red giant branch: the value and metallicity dependence of Reimers’ η in globular clusters journal February 2015
The DESI Experiment, a whitepaper for Snowmass 2013 preprint January 2013

Cited By (2)

Impact of inhomogeneous reionization on the Lyman-α forest journal May 2019
Improved renormalization group computation of likelihood functions for cosmological data sets journal August 2019

Figures / Tables (13)

FIG. 1.(p. 12)figure FIG. 1.
FIG. 2.(p. 13)figure FIG. 2.
FIG. 3.(p. 13)figure FIG. 3.
FIG. 4.(p. 15)figure FIG. 4.
TABLE I.(p. 15)table TABLE I.
FIG. 5.(p. 17)figure FIG. 5.
TABLE II.(p. 18)table TABLE II.
FIG. 6.(p. 19)figure FIG. 6.
FIG. 7.(p. 20)figure FIG. 7.
FIG. 8.(p. 21)figure FIG. 8.
TABLE III.(p. 22)table TABLE III.
FIG. 10.(p. 24)figure FIG. 10.
FIG. 9.(p. 24)figure FIG. 9.

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79 ASTRONOMY AND ASTROPHYSICS