Clustering of Luminous Red Galaxies III: Detection of the Baryon Acoustic Peak in the 3-point Correlation Function

Understand

We present the 3-point function \xi_3 and Q_3=\xi_3/\xi_2^2 for a spectroscopic sample of luminous red galaxies (LRG) from SDSS DR6 & DR7.

• We find a strong (S/N$>$6) detection of $Q_3$ on scales of 55-125 Mpc/h, with a well defined peak around 105 Mpc/h in all \xi_2, \xi_3 and Q_3, in excellent agreement with the predicted shape and location of the imprint of the baryon acoustic oscillations (BAO).
• We use very large simulations to asses and test the significance of our measurement.
• Models without the BAO peak are ruled out by the $Q_3$ data with 99% confidence.