A MEASUREMENT OF THE SECONDARY-CMB AND MILLIMETER-WAVE-FOREGROUND BISPECTRUM USING 800 deg²OF SOUTH POLE TELESCOPE DATA

We present a measurement of the angular bispectrum of the millimeter-wave sky observing bands centered at roughly 95, 150, and 220 GHz, on angular scales 1^\ \ \θ \ 10^\ (multipole number 1000\ l \ 10000). At these frequencies and angular scales, the main to the bispectrum are expected to be the thermal-Zel'dovich (tSZ) effect and emission from extragalactic sources, dusty, star-forming galaxies (DSFGs) and active galactic nuclei. measure the bispectrum in 800 ² of three-band South Pole data, and we use a multi-frequency fitting procedure to separate the of the tSZ effect from the extragalactic source contribution. We detect the bispectrum of the tSZ effect at $>$10\σ, the component of the extragalactic source bispectrum at $>$5\σ in frequency band, and the bispectrum due to the clustering of DSFGs---i.e., clustered cosmic infrared background (CIB) bispectrum---at $>$5\σ. is the first reported detection of the clustered CIB bispectrum. We use measured tSZ bispectrum amplitude, compared to model predictions, to the normalization of the matter power spectrum to be \σ₈ =0.787 \± 0.031 and to predict the amplitude of the tSZ power spectrum at l =3000. This prediction improves our ability to separate the thermal and contributions to the total SZ power spectrum. The addition of data improves our constraint on the tSZ power spectrum amplitude by factor of two compared to power spectrum measurements alone and demonstrates preference for a nonzero kinematic SZ (kSZ) power spectrum, with a derived on the kSZ amplitude at $l=3000$ of A_kSZ = 2.9 \± 1.6 \\\μK², or A_kSZ = 2.6 \± 1.8 \\ \μK² if the default A_kSZ > 0 prior removed.