Threshold Clustering Functions and Thermal Inhomogeneities in the Lyman-Alpha Forest

Abstract

We introduce to astrophysics the threshold probability functions S_2, C_2, and D_2 first derived by \citet{torq+88}, which effectively samples the flux probability distribution (PDF) of the Lya forest at different spatial scales. These statistics are tested on mock Lya forest spectra based on various toy models for HeII reionization, with homogeneous models with various temperature-density relations as well as models with temperature inhomogeneities. These mock samples have systematics and noise added to simulate the latest Sloan Digital Sky Survey Data Release 7 (SDSS DR7) data. We find that the flux PDF from SDSS DR7 can be used to constrain the temperature-density relation $\gamma$ (where $T\propto (1+\Delta {)}^{\gamma -1}$) of the intergalactic medium (IGM) at z=2.5 to a precision of $\Delta \gamma =0.2$ at $\sim 4\sigma$ confidence. The flux PDF is degenerate to temperature inhomogeneities in the IGM arising from HeII reionization, but we find S_2 can detect these inhomogeneities at $\sim 3\sigma$, with the assumption that the flux continuum of the Lya forest can be determined to 9% accuracy, approximately the error from current fitting methods. If the quasar continuum can be determined to 3% accuracy, then S_2 is capable of constraining the characteristic scale of temperature inhomogeneities, with $\sim 4\sigma$ differentiation between toy models with hot bubble radii of 50 Mpc/h and 25 Mpc/h, comoving.

13 pages, 10 figures; Accepted by ApJ

References in corpus (9)

• The Sloan Digital Sky Survey Quasar Catalog V. Seventh Data Release
• A Superior Descriptor of Random Textures and Its Predictive Capacity
• HeII Reionization and its Effect on the IGM
• A Direct Precision Measurement of the Intergalactic Lyman-alpha Opacity at 2<z<4.2
• An improved measurement of the flux distribution of the Ly-alpha forest in QSO absorption spectra: the effect of continuum fitting, metal contamination and noise properties
• The History and Morphology of Helium Reionization
• The Acoustic Peak in the Lyman Alpha Forest
• Inhomogeneous Helium Reionization and the Equation of State of the Intergalactic Medium
• The Probability Distribution of the Lya transmitted flux from a sample of SDSS quasars

Cited by in corpus (11)

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• Lyα emission line reconstruction for high-$z$ QSOs
• IGM Constraints from the SDSS-III/BOSS DR9 Ly-alpha Forest Flux Probability Distribution Function
• Mean-flux Regulated PCA Continuum Fitting of SDSS Lyman-alpha Forest Spectra
• Improved reconstructions of random media using dilation and erosion processes
• The Signatures of Large-scale Temperature and Intensity Fluctuations in the Lyman-alpha Forest
• Neutrino Signatures on the High Transmission Regions of the Lyman-alpha Forest
• The impact of temperature fluctuations on the large-scale clustering of the Ly$\alpha$ forest
• Constraining the Fluctuating Gunn-Peterson Approximation Using Lyman-$\alpha$ Forest Tomography at $z=2$
• Detecting preheating in proto-clusters with Lyman-$\alpha$ Forest Tomography