Correlation between galaxies and QSO in the SDSS:na signal from gravitational lensing magnification?

摘要: We report a detection of galaxy-QSO cross-correlation w_GQ in the Sloan Digital Sky Survey (SDSS) Early Data Release (EDR) over 0.2-30 arc-minute scales. cross-correlate galaxy samples different mean depths r'=19-22 (z_G =0.15-0.35) with main QSO population (i'<19.1) at z_Q=1.6. find significant positive correlation all cases except for faintest QSOs, as expected if signal were due to weak lensing magnification. The amplitude on scales is about 20%. This few times larger than currently from LCDM but confirms, higher significance, previous measurements by several groups. When compared galaxy-galaxy w_GG, interpretation indicates strong and steep non-linear underlaying matter fluctuations: sigma=400 0.2 Mpc/h, contradiction modeling fluctuations. also detect normalized skewness (galaxy-galaxy-QSO correlation) S_3=21 +/-6 z=0.15 (S_3= 14 +/- 4 z=0.35), which sigma low, expectations. These observational trends can be reconciled flat Lambda universe sigma_8=1, provided linear spectrum steeper (n = 1) model these small (cluster) Under this interpretation, distribution traces variance an that 100 smaller: ie galaxies are anti-bias b=0.1 scales, increasing b=1 10 Mpc/h.