Vol 10, No 2 (2010) / Gong

Primordial non-Gaussianity from LAMOST surveys

Yan Gong, Xin Wang, Zheng Zheng, Xue-Lei Chen


The primordial non-Gaussianity (PNG) in the matter density perturbation is a very powerful probe of the physics of the very early Universe. The local PNG can induce a distinct scale-dependent bias on the large scale structure distribution of galaxies and quasars, which could be used for constraining it. We study the detection limits of PNG from the surveys of the LAMOST telescope. The cases of the main galaxy survey, the luminous red galaxy (LRG) survey, and the quasar survey of different magnitude limits are considered. We find that the Main1 sample (i.e. the main galaxy survey which is one magnitude deeper than the SDSS main galaxy survey, or r < 18.8) could only provide a very weak constraint on PNG. For the Main2 sample (r < 19.8) and the LRG survey, the 2σ (95.5%) limits on the PNG parameter fNL are |fNL| < 145 and |fNL| < 114 respectively, which are comparable to the current limit from cosmic microwave background (CMB) data. The quasar survey could provide a much more stringent constraint, and we find that the 2σ limit for |fNL| is between 50 and 103, depending on the magnitude limit of the survey. With Planck-like priors on cosmological parameters, the quasar survey with g < 21.65 would improve the constraint to |fNL| < 43 (2σ).We also discuss the possibility of further tightening the constraint by using the relative bias method proposed by Seljak.


cosmology:large scale structure

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