Precision measurements of higher order angular galaxy correlations using 11 million SDSS galaxies

We present estimates of the N-point galaxy area-averaged angular correlation functions ω̄_N(θ) for N = 2, . . ., 7 from the third data release of the Sloan Digital Sky Survey (SDSS). The sample was selected from galaxies with 18 ≤ r < 21 and is the largest ever used to study higher order correlations. The measured ω̄(θ) are used to calculate the projected, S_N, and real-space, S_N, hierarchical amplitudes. This produces highly precise measurements over 0.2-10 h^-1 Mpc, which are consistent with Gaussian primordial density fluctuations. The measurements suggest that higher order galaxy bias is non-negligible, as defining b₁ = 1 yields 02 = -0.24 ± 0.08. We report the first SDSS measurement of marginally significant third-order bias, c₃, -0.98 ± 0.89, which suggests that bias terms may be significant to even higher order. Previous measurements of c₂ have yielded inconsistent results. Inconsistencies would be expected if different data sets sample different galaxy types, especially if different galaxy types exhibit different higher order bias. We find that early-type galaxies exhibit significantly different behavior than late types at both small and large scales. At large scales (r > 1 h^-1 Mpc), we find that the S_N for late-type galaxies are lower than for early types, implying a significant difference between their higher order bias. We find b_1,early = 1-36±0.04, c_2,early = 0.30 ± 0.10, b_1,late = 0.81±0.03, and c_2,late = -0.70±0.08. Our results are robust against the systematic effects of reddening and seeing. The latter introduces minor structure in ω̄_N(θ).