H <scp>i</scp> constraints from the cross-correlation of eBOSS galaxies and Green Bank Telescope intensity maps

We present the joint analysis of Neutral Hydrogen (HI) Intensity Mapping observations with three galaxy samples: Luminous Red Galaxy (LRG) and Emission Line (ELG) samples from eBOSS survey, WiggleZ Dark Energy Survey sample. The HI intensity maps are Green Bank Telescope redshifted 21cm emission on 100deg2 covering redshift range $0.6<z<1.0$. process data by separating removing foregrounds FastICA, construct a transfer function to correct for effects foreground removal signal. cross-correlate cleaned study overall amplitude as well scale-dependence power spectrum. also qualitatively compare our findings predictions semi-analytic evolution simulation. cross-correlations constrain quantity $\Omega_{{HI}} b_{{HI}} r_{{HI},{opt}}$ at an effective scale $k_{eff}$, where $\Omega_{HI}$ is density fraction, $b_{HI}$ bias, $r_{{HI},{opt}}$ galaxy-hydrogen correlation coefficient, which dependent content optical At $k_{eff}=0.31 \, h/{Mpc}$ we find r_{{HI},{Wig}} = [0.58 \pm 0.09 {(stat) 0.05 {(sys)}}] \times 10^{-3}$ GBT-WiggleZ, r_{{HI,{ELG}}} [0.40 0.04 GBT-ELG, r_{{HI},{LRG}} [0.35 0.08 0.03 GBT-LRG, $z\simeq 0.8$. report results $k_{eff}=0.24 $k_{eff}=0.48 h/{Mpc}$. With little information parameters beyond local Universe, these amongst most precise constraints neutral hydrogen fluctuations in underexplored range.