A Measurement of the Secondary-cmb and Millimeter-wave-foreground Bispectrum Using 800 Square Degrees of South Pole Telescope Data

We present a measurement of the angular bispectrum of the millimeter-wave sky in observing bands centered at roughly 95, 150, and 220 GHz, on angular scales of 1 . θ . 10 (multipole number 1000 . l . 10,000). At these frequencies and angular scales, the main contributions to the bispectrum are expected to be the thermal Sunyaev-Zel’dovich (tSZ) effect and emission from extragalactic sources, predominantly dusty, star-forming galaxies (DSFGs) and active galactic nuclei. We measure the bispectrum in 800 deg of three-band South Pole Telescope data, and we use a multi-frequency fitting procedure to separate the bispectrum of the tSZ effect from the extragalactic source contribution. We simultaneously detect the bispectrum of the tSZ effect at >10σ, the unclustered component of the extragalactic source bispectrum at >5σ in each frequency band, and the bispectrum due to the clustering of DSFGs—i.e., the clustered cosmic infrared background (CIB) bispectrum—at >5σ. This is the first reported detection of the clustered CIB bispectrum. We use the measured tSZ bispectrum amplitude, compared to model predictions, to constrain 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 kinematic contributions to the total SZ power spectrum. The addition of bispectrum data improves our constraint on the tSZ power spectrum amplitude by a factor of two compared to power spectrum measurements alone and demonstrates a preference for a nonzero kinematic SZ (kSZ) power spectrum, with a derived constraint on the kSZ amplitude at l = 3000 of AkSZ = 2.9± 1.6 μK, or AkSZ = 2.6± 1.8 μK if the default AkSZ > 0 prior is removed. Subject headings: cosmology: observations — cosmology: cosmic background radiation — methods: data analysis Electronic address: [email protected] 1 Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL, USA 60637 2 Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA 60637 3 Enrico Fermi Institute, University of Chicago, Chicago, IL, USA 60637 4 Liberal Arts Department, School of the Art Institute of Chicago, Chicago, IL, USA 60603 5 High Energy Physics Division, Argonne National Laboratory, Argonne, IL, USA 60439 6 University of Chicago, Chicago, IL, USA 60637 7 Department of Physics, University of Chicago, Chicago, IL, USA 60637 8 Argonne National Laboratory, Argonne, IL, USA 60439 9 NIST Quantum Devices Group, Boulder, CO, USA 80305 10 Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada 11 Department of Physics, University of California, Berkeley, CA, USA 94720 12 Department of Astrophysical and Planetary Sciences and Department of Physics, University of Colorado, Boulder, CO, USA 80309 13 Department of Physics, University of California, Davis, CA, USA 95616 14 Physics Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA 94720 15 California Institute of Technology, Pasadena, CA, USA 91125 16 Department of Physics, University of Michigan, Ann Arbor,