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首页> 外文期刊>The Astrophysical journal >TOWARD A MEASUREMENT OF THE COSMOLOGICAL GEOMETRY AT z ~ 2: PREDICTING Lya FOREST CORRELATION IN THREE DIMENSIONS AND THE POTENTIAL OF FUTURE DATA SETS
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TOWARD A MEASUREMENT OF THE COSMOLOGICAL GEOMETRY AT z ~ 2: PREDICTING Lya FOREST CORRELATION IN THREE DIMENSIONS AND THE POTENTIAL OF FUTURE DATA SETS

机译：面向z〜2的宇宙几何学测量，预测3个维度的Lya森林相关性和未来数据集的潜力

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The correlation between Lya absorption in the spectra of quasar pairs can be used to measure the transverse distance scale at z ～ 2, which is sensitive to the cosmological constant (Ω_Λ) or other forms of vacuum energy. Using hydro-PM simulations, I compute the three-dimensional power spectrum of the Lyα forest flux, P_F(k), from which the redshift-space anisotropy of the correlation can be obtained. I compute directly the linear theory bias parameters of the Lya forest, potentially allowing simulation results to be extended to arbitrarily large scales. I investigate the dependence of P_F(k) on the primordial power spectrum, the temperature-density relation of the gas, and the mean flux decrement, finding that the redshift-space anisotropy is relatively insensitive to these parameters. A table of results is provided for different parameter variations. I investigate the constraint that can be obtained on Ω_Λ using quasars from a large survey. Assuming 13(θ/1′)~2 pairs at a separation of less than θ and including separations less than 10~', a measurement to approx< 5% can be made if simulations can predict the redshift-space anisotropy with approx<5% accuracy or to approx<10% if the anisotropy must be measured from the data. The Sloan Digital Sky Survey (SDSS) will obtain spectra for a factor of ～5 fewer pairs than this, so follow-up observations of fainter pair candidates will be necessary. I discuss the requirements on the spectral resolution and signal-to-noise ratio (SDSS quality spectra are sufficient). I find that a box size of ～40 h~(-1) Mpc and a resolution of ～40 h~(-1) kpc are necessary for convergence of the calculations to approx<5% on all relevant scales, although somewhat poorer resolution can be used for large scales.
机译：类星体光谱中Lya吸收之间的相关性可用于测量z〜2处的横向距离尺度，该尺度对宇宙常数（Ω_Λ）或其他形式的真空能敏感。利用水动力-PM模拟，我计算了Lyα森林通量的三维功率谱P_F（k），从中可以获得相关性的红移-空间各向异性。我直接计算Lya森林的线性理论偏差参数，可能使模拟结果扩展到任意大比例尺。我研究了P_F（k）对原始功率谱的依赖性，气体的温度-密度关系以及平均通量递减，发现红移空间各向异性对这些参数相对不敏感。提供了针对不同参数变化的结果表。我研究了使用大范围调查中的类星体可以在Ω_Λ上获得的约束。假设13个（θ/ 1'）〜2对之间的距离小于θ并且包括小于10''的距离，如果模拟可以预测约<5的红移空间各向异性，则可以测量到大约<5％ ％精度;如果必须根据数据测量各向异性，则精度约为<10％。 Sloan Digital Sky Survey（SDSS）将获得的光谱比该光谱少约5倍，因此需要对较暗的候选光谱进行后续观测。我讨论了对光谱分辨率和信噪比的要求（SDSS质量光谱就足够了）。我发现，在所有相关标度上，要使计算收敛到大约<5％，框大小约为40 h〜（-1）Mpc和分辨率约为40 h〜（-1）kpc是必要的。可用于大规模。

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