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Title: Modeling the Lyα Forest in Collisionless Simulations

Journal Article · · The Astrophysical Journal (Online)
 [1];  [2];  [3];  [2]
  1. Max Planck Inst. for Astronomy, Heidelberg (Germany); Heidelberg Univ. (Germany)
  2. Max Planck Inst. for Astronomy, Heidelberg (Germany)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
+ Show Author Affiliations

Cosmological hydrodynamic simulations can accurately predict the properties of the intergalactic medium (IGM), but only under the condition of retaining the high spatial resolution necessary to resolve density fluctuations in the IGM. This resolution constraint prohibits simulating large volumes, such as those probed by BOSS and future surveys, like DESI and 4MOST. To overcome this limitation, we present in this paper "Iteratively Matched Statistics" (IMS), a novel method to accurately model the Lyα forest with collisionless N-body simulations, where the relevant density fluctuations are unresolved. We use a small-box, high-resolution hydrodynamic simulation to obtain the probability distribution function (PDF) and the power spectrum of the real-space Lyα forest flux. These two statistics are iteratively mapped onto a pseudo-flux field of an N-body simulation, which we construct from the matter density. We demonstrate that our method can reproduce the PDF, line of sight and 3D power spectra of the Lyα forest with good accuracy (7%, 4%, and 7% respectively). We quantify the performance of the commonly used Gaussian smoothing technique and show that it has significantly lower accuracy (20%–80%), especially for N-body simulations with achievable mean inter-particle separations in large-volume simulations. Finally, in addition, we show that IMS produces reasonable and smooth spectra, making it a powerful tool for modeling the IGM in large cosmological volumes and for producing realistic "mock" skies for Lyα forest surveys.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1379569
Journal Information:
The Astrophysical Journal (Online), Journal Name: The Astrophysical Journal (Online) Journal Issue: 2 Vol. 827; ISSN 1538-4357
Publisher:
Institute of Physics (IOP)Copyright Statement
Country of Publication:
United States
Language:
English

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Cited By (5)

An algorithmic framework for the optimization of computationally expensive bi-fidelity black-box problems journal June 2019
A New Precision Measurement of the Small-scale Line-of-sight Power Spectrum of the Ly α Forest journal December 2017
A Fundamental Test for Galaxy Formation Models: Matching the Lyman- α Absorption Profiles of Galactic Halos Over Three Decades in Distance journal May 2018
A Novel Statistical Method for Measuring the Temperature–Density Relation in the IGM Using the b – N H i Distribution of Absorbers in the Ly α Forest journal May 2019
TARDIS. I. A Constrained Reconstruction Approach to Modeling the z ∼ 2.5 Cosmic Web Probed by Ly α Forest Tomography journal December 2019

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79 ASTRONOMY AND ASTROPHYSICS
intergalactic medium
numerical methods