The Atacama Cosmology Telescope: A Measurement of the Thermal Sunyaev-Zel'dovich Effect Using the Skewness of the CMB Temperature Distribution
astro-ph.CO
/ Authors
Michael J. Wilson, Blake D. Sherwin, J. Colin Hill, Graeme Addison, Nick Battaglia, J. Richard Bond, Sudeep Das, Mark J. Devlin, Joanna Dunkley, Rolando Dunner
and 28 more authors
Joseph W. Fowler, Megan B. Gralla, Amir Hajian, Mark Halpern, Matt Hilton, Adam D. Hincks, Renee Hlozek, Kevin Huffenberger, John P. Hughes, Arthur Kosowsky, Thibaut Louis, Tobias A. Marriage, Danica Marsden, Felipe Menanteau, Kavilan Moodley, Michael D. Niemack, Michael R. Nolta, Lyman A. Page, Bruce Partridge, Erik D. Reese, Neelima Sehgal, Jon Sievers, David N. Spergel
/ Abstract
We present a detection of the unnormalized skewness <T^3> induced by the thermal Sunyaev-Zel'dovich (tSZ) effect in filtered Atacama Cosmology Telescope (ACT) 148 GHz cosmic microwave background temperature maps. Contamination due to infrared and radio sources is minimized by template subtraction of resolved sources and by constructing a mask using outlying values in the 218 GHz (tSZ-null) ACT maps. We measure <T^3>= -31 +- 6 μK^3 (measurement error only) or +- 14 μK^3 (including cosmic variance error) in the filtered ACT data, a 5-sigma detection. We show that the skewness is a sensitive probe of sigma_8, and use analytic calculations and tSZ simulations to obtain cosmological constraints from this measurement. From this signal alone we infer a value of sigma_8= 0.79 +0.03 -0.03 (68 % C.L.) +0.06 -0.06 (95 % C.L.). Our results demonstrate that measurements of non-Gaussianity can be a useful method for characterizing the tSZ effect and extracting the underlying cosmological information.