Large-Scale 3D Mapping of the Intergalactic Medium with the Lyman Alpha Forest Using Hydrodynamic Simulations and SDSS-III BOSS DR12
Abstract
Maps of the large-scale structure of the Universe at redshifts 2 < z < 4 can be made with the Lyalpha forest, which are complementary to low-redshift galaxy surveys. We apply the Wiener interpolation method of Caucci et al. to construct three-dimensional maps from sets of Lyman alpha forest spectra, evaluating its performance with cosmological hydrodynamic simulations and also applying these methods to BOSS DR12 data. We discuss local smoothing and also show that the simulated map resolutions are accessible to current observational surveys. We find from the simulation study that both the density field and the statistical properties of the IGM are recovered well enough that the resulting IGM maps can be meaningfully considered to represent large-scale maps of the universe, in agreement with Caucci et al., on larger scales and for sparser sightlines than had been tested previously. Quantitatively, for sightline parameters comparable to current and near future surveys, the correlation coefficient between true and reconstructed fields is r > 0.9 on scales > 30h-1Mpc. The properties of the maps are relatively insensitive to the precise form of the covariance matrix used. The final BOSS quasar Lyman alpha forest sample allows us to make maps with a resolution of ∼ 60 h -1Mpc over a volume of ∼ 15 h-3 Gpc3 between redshifts 1.9 and 2.3. We make large maps of the BOSS DR12 IGM field and study global statistical properties of the maps with auto-correlation, slice plots, local peaks, probability density functions, point-by-point scatter, and percolation techniques to identify individual structures.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 2017
- Bibcode:
- 2017PhDT........40O
- Keywords:
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- Physics;Astrophysics