An improved model for the effect of correlated Si-III absorption on the one-dimensional Lyman-$\alpha$ forest power spectrum

Abstract

We present an analysis of Si III absorption and its effect on the 1D Ly$\alpha$ forest power spectrum using the Sherwood-Relics hydrodynamical simulation suite. In addition to oscillations from the Ly$\alpha$--Si III cross correlation that are damped toward smaller scales, we find an enhancement in small-scale power that has been ignored in previous studies. We therefore develop a new analytical fitting function that captures two critical effects that have previously been neglected: distinct Ly$\alpha$ and Si III line profiles, and a variable ratio for coeval Ly$\alpha$ and Si III optical depths. In contrast to earlier work, we also predict amplitudes for the Si III power spectrum and Ly$\alpha$--Si III cross power spectrum that decrease toward lower redshift due to the hardening metagalactic UV background spectrum at $z\lesssim 3.5$. The fitting function is validated by comparison against multiple simulated datasets at redshifts $2.2\le z\le 5.0$ and wavenumbers $k<0.2\mathrm{s}\mathrm{k}{\mathrm{m}}^{-1}$. Our model has little effect on existing warm dark matter constraints from the Ly$\alpha$ forest when adopting a physically motivated prior on the silicon abundance. It will, however, be an essential consideration for future, high precision Ly$\alpha$ forest power spectrum measurements.

arXiv comment16 pages, 12 figures, accepted to MNRAS. The accepted version now includes oscillation damping at large scales

References in corpus (40)

• The chemical composition of the Sun
• The cosmological simulation code GADGET-2
• Cosmological parameter analysis including SDSS Ly-alpha forest and galaxy bias: constraints on the primordial spectrum of fluctuations, neutrino mass, and dark energy
• Warm Dark Matter as a solution to the small scale crisis: new constraints from high redshift Lyman-alpha forest data
• Equation of State of the Photoionized Intergalactic Medium
• The Lyman-alpha Forest Power Spectrum from the Sloan Digital Sky Survey
• The Enrichment of the Intergalactic Medium with Adiabatic Feedback I: Metal Cooling and Metal Diffusion
• Towards a Precise Measurement of Matter Clustering: Lyman-alpha Forest Data at Redshifts 2-4
• Metallicity of the intergalactic medium using pixel statistics. II. The distribution of metals as traced by C IV
• P3M-SPH simulations of the Lyman-alpha Forest
• The Physics of the Intergalactic Medium
• The Evolution of the Intergalactic Medium
• Detection of Extended He II Reionization in the Temperature Evolution of the Intergalactic Medium
• Strong bound on canonical ultra-light axion dark matter from the Lyman-alpha forest
• Inferring the dark matter power spectrum from the Lyman-alpha forest in high-resolution QSO absorption spectra
• The one-dimensional Ly-alpha forest power spectrum from BOSS
• Lyman-alpha Forest Constraints on the Mass of Warm Dark Matter and the Shape of the Linear Power Spectrum
• A Refined Measurement of the Mean Transmitted Flux in the Ly-alpha Forest over 2 < z < 5 Using Composite Quasar Spectra
• Consistent modelling of the meta-galactic UV background and the thermal/ionization history of the intergalactic medium
• The Sherwood simulation suite: overview and data comparisons with the Lyman-alpha forest at redshifts 2 < z < 5
• The one-dimensional power spectrum from the SDSS DR14 Ly$\alpha$ forests
• New synthesis models of consistent extragalactic background light over cosmic time
• Revealing reionization with the thermal history of the intergalactic medium: new constraints from the Lyman-$\alpha$ flux power spectrum
• Probing the thermal state of the intergalactic medium at $z>5$ with the transmission spikes in high-resolution Ly$\alpha$ forest spectra
• Voigt Profile Fitting to Quasar Absorption Lines: An Analytic Approximation to the Voigt-Hjerting Function
• Metallicity of the intergalactic medium using pixel statistics: III. Silicon
• The photoheating of the intergalactic medium in synthesis models of the UV background
• A consistent and robust measurement of the thermal state of the IGM at $2\le z\le 4$ from a large sample of Ly$\alpha$ forest spectra: Evidence for late and rapid HeII reionization
• On the intergalactic temperature-density relation
• New Constraints on Warm Dark Matter from the Lyman-$\alpha$ Forest Power Spectrum
• The Lyman-alpha forest power spectrum from the XQ-100 Legacy Survey
• Resolving the high redshift Lyman-alpha forest in smoothed particle hydrodynamics simulations
• Unveiling Dark Matter free-streaming at the smallest scales with high redshift Lyman-alpha forest
• The Sherwood-Relics simulations: overview and impact of patchy reionization and pressure smoothing on the intergalactic medium
• The Dark Energy Spectroscopic Instrument: One-dimensional power spectrum from first Lyman-$\alpha$ forest samples with Fast Fourier Transform
• Optimal 1D Ly$\alpha$ Forest Power Spectrum Estimation -- II. KODIAQ, SQUAD & XQ-100
• The metallicity distribution of HI systems in the EAGLE cosmological simulation
• Constraining Mixed Dark Matter models with high redshift Lyman-alpha forest data
• Constraints on Primordial Magnetic Fields from the Lyman-α forest
• Measuring photo-ionization rate and mean free path of HeII ionizing photons at $2.5\le z\le 3.6$: Evidence for late and rapid HeII reionization Part-II