The Lyman-beta forest as a cosmic thermometer

Abstract

We present a comprehensive analysis of high resolution hydrodynamic simulations in terms of Lyman-alpha and Lyman-beta one dimensional flux power spectra ($P_{\alpha \alpha }$ and $P_{\beta \beta }$). In particular, we focus on the behaviour that the flux auto-power spectra and cross-power spectra ($P_{\alpha \beta }$) display when the intergalactic medium (IGM) thermal history is changed in a range of values that bracket a reference model, while cosmological parameters are kept fixed to best fit the cosmic microwave background data. We present empirical fits that describe at the sub-percent level the dependence of the power spectra on the thermal parameters. At the largest scales, the power spectra show a constant bias between each other that is set by the parameters describing the IGM thermal state. The cross-power spectrum has an oscillatory pattern and crosses zero at a scale which depends on $T_0$, the IGM temperature at the mean density, for reasonable values of the power-law index $\gamma$ of the IGM temperature-density relation ($T=T_0(1+\delta {)}^{\gamma -1}$). By performing a Fisher matrix analysis, we find that the power spectrum $P_{\beta \beta }$ is more sensitive to the thermal history than $P_{\alpha \alpha }$ alone, due to the fact that it probes denser regions than Lyman-alpha. When we combine the power and cross spectra the constraints on $\gamma$ can be improved by a factor $\sim 4$, while the constraints on $T_0$ improve by a factor of $\sim 2$. We address the role of signal-to-noise and resolution by mocking realistic observations and we conclude that the framework presented in this work can significantly improve the knowledge of the IGM thermal state, which will in turn guarantee better constraints on IGM-derived cosmological parameters.

33 pages, 15 figures; matches version published in JCAP

References in corpus (45)

• Planck 2013 results. XVI. Cosmological parameters
• The cosmological simulation code GADGET-2
• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
• X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
• Constraining Warm Dark Matter candidates including sterile neutrinos and light gravitinos with WMAP and the Lyman-alpha forest
• 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
• Cosmological parameters from combining the Lyman-alpha forest with CMB, galaxy clustering and SN constraints
• Baryon Acoustic Oscillations in the Ly-α forest of BOSS quasars
• The Lyman Alpha Forest in the Spectra of QSOs
• The Lyman-alpha Forest Power Spectrum from the Sloan Digital Sky Survey
• Towards a Precise Measurement of Matter Clustering: Lyman-alpha Forest Data at Redshifts 2-4
• The thermal history of the intergalactic medium
• The Linear Theory Power Spectrum from the Lyman-alpha Forest in the Sloan Digital Sky Survey
• P3M-SPH simulations of the Lyman-alpha Forest
• The Physics of the Intergalactic Medium
• The Observed Probability Distribution Function, Power Spectrum, and Correlation Function of the Transmitted Flux in the Lyman-alpha Forest
• Detection of Extended He II Reionization in the Temperature Evolution of the Intergalactic Medium
• Inferring the dark matter power spectrum from the Lyman-alpha forest in high-resolution QSO absorption spectra
• Measurement of Baryon Acoustic Oscillations in the Lyman-alpha Forest Fluctuations in BOSS Data Release 9
• HeII Reionization and its Effect on the IGM
• The Evolution of the Effective Equation of State of the IGM
• Toward a Measurement of the Cosmological Geometry at z~2: Predicting Lyman-alpha Forest Correlation in Three Dimensions, and the Potential of Future Data Sets
• The one-dimensional Ly-alpha forest power spectrum from BOSS
• The Thermal Memory of Reionization History
• Cosmological and astrophysical parameters from the SDSS flux power spectrum and hydrodynamical simulations of the Lyman-alpha forest
• A Measurement of Small Scale Structure in the 2.2 < z < 4.2 Lyman-alpha Forest
• Possible evidence for an inverted temperature-density relation in the intergalactic medium from the flux distribution of the Lyman-alpha forest
• Constraints from the Lyman alpha forest power spectrum
• 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
• Physical effects on the Lyman-alpha forest flux power spectrum: damping wings, ionizing radiation fluctuations, and galactic winds
• The power spectrum of the flux distribution in the Lyman-alpha forest of a Large sample of UVES QSO Absorption Spectra (LUQAS)
• The thermal history of the intergalactic medium down to redshift z=1.5: a new curvature measurement
• A consistent determination of the temperature of the intergalactic medium at redshift z=2.4
• The impact of feedback from galaxy formation on the Lyman-alpha transmitted flux
• Temperature fluctuations in the intergalactic medium
• The Lyman-alpha forest in a blazar-heated Universe
• New approach for precise computation of Lyman-alpha forest power spectrum with hydrodynamical simulations
• Generating mock data sets for large-scale Lyman-α forest correlation measurements
• A wavelet analysis of QSO spectra
• On Modeling and Measuring the Temperature of the z~5 IGM
• The bispectrum of the Lyman-alpha forest at z~2-2.4 from a Large sample of UVES QSO Absorption Spectra (LUQAS)
• The effect of (strong) discrete absorption systems on the lyman alpha forest flux power spectrum
• Beyond Lyman-alpha: Constraints and Consistency Tests from the Lyman-beta Forest
• Detection of Lyβauto-correlations and Lyα-Lyβcross-correlations in BOSS Data Release 9

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• Baryon acoustic oscillations at z = 2.34 from the correlations of Ly$\alpha$ absorption in eBOSS DR14
• Inferring the IGM thermal history during reionisation with the Lyman-$\alpha$ forest power spectrum at redshift $z\simeq 5$
• Constraining Reionization with the $z\sim 5-6$ Lyman-$\alpha$ Forest Power Spectrum: the Outlook after Planck
• Helium Reionization Simulations. II. Signatures of Quasar Activity on the IGM
• A measurement of the Lyman-beta forest power spectrum and its cross with the Lyman-alpha forest in X-Shooter XQ-100
• Constraining the temperature-density relation of the intergalactic medium with the Lyman-$\alpha$ and $\beta$ forests
• Constraining the Fluctuating Gunn-Peterson Approximation Using Lyman-$\alpha$ Forest Tomography at $z=2$
• Probing Time-Dependent Dark Energy with the Flux Power Spectrum of the Lyman $\alpha$ Forest