تقرير
Log-Poisson Non-Gaussianity of Ly$\alpha$ Transmitted Flux Fluctuations at High Redshift
| العنوان: | Log-Poisson Non-Gaussianity of Ly$\alpha$ Transmitted Flux Fluctuations at High Redshift |
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| المؤلفون: | Lu, Yi, Zhu, Weishan, Chu, Yaoquan, Feng, Long-long, Fang, Li-Zhi |
| سنة النشر: | 2010 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Cosmology and Nongalactic Astrophysics |
| الوصف: | We investigate the non-Gaussian features of the IGM at redshift $z\sim 5 - 6$ using Ly$\alpha$ transmitted flux of quasar absorption spectra and cosmological hydrodynamic simulation of the concordance $\Lambda$CDM universe. We show that the neutral hydrogen mass density field and Ly$\alpha$ transmitted flux fluctuations possess all the non-Gaussian features predicted by the log-Poisson hierarchy, which depends only on two dimensionless parameters $\beta$ and $\gamma$, describing, respectively, the intermittence and singularity of the random fields. We find that the non-Gaussianity of the Ly$\alpha$ transmitted flux of quasars from $z=4.9$ to $z=6.3$ can be well reconstructed by the hydrodynamical simulation samples. Although the Gunn-Peterson optical depth and its variance underwent a significant evolution in the redshift range of $5 - 6$, the intermittency measured by $\beta$ is almost redshift-independent in this range. More interesting, the intermittency of quasar's absorption spectra on physical scales $0.1-1$ h$^{-1}$Mpc in redshift $5 - 6$ are found to be about the same as that on physical scales $1-10$ h$^{-1}$Mpc at redshifts $2 - 4$. Considering the Jeans length is less than 0.1 h$^{-1}$Mpc at $z\sim 5$, and $1$ h$^{-1}$Mpc at $z\sim 2$, these results imply that the nonlinear evolution in high and low redshifts will lead the cosmic baryon fluid to a state similar to fully developed turbulence. The log-Poisson high order behavior of current high redshift data of quasar's spectrum can be explained by uniform UV background in the redshift range considered. We also studied the log-Poisson non-Gaussianity by considering inhomogeneous background. With several simplified models of inhomogeneous background, we found the effect of the inhomogeneous background on the log-Poisson non-Gaussianity is not larger than 1-sigma. Comment: 12 pages 10 figures, accepted by MNRAS |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1111/j.1365-2966.2010.17130.x |
| URL الوصول: | http://arxiv.org/abs/1006.1933 |
| رقم الأكسشن: | edsarx.1006.1933 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1111/j.1365-2966.2010.17130.x |
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