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...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 dif- ferent magnitude limits are considered. We find that the Mainl 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 2or （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 2a 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 I fNLI 〈 43 （2or）. We also discuss the possibility of further tightening the constraint by using the relative bias method proposed by Seljak.展开更多
基金supported by the National Natural Science Foundation of China under the Distinguished Young Scholar Grant 10525314the Key Project Grant 10533010,by the ChineseAcademy of Sciences under grant KJCX3-SYW-N2by the Ministry of Science and Technologynational basic science Program (Project 973) under grant No. 2007CB815401
文摘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 dif- ferent magnitude limits are considered. We find that the Mainl 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 2or （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 2a 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 I fNLI 〈 43 （2or）. We also discuss the possibility of further tightening the constraint by using the relative bias method proposed by Seljak.
