Atacama Cosmology Telescope : A Measurement of the Thermal Sunyaev-Zel ’ dovich Effect Using the Skewness of the CMB Temperature Distribution

We present a detection of the unnormalized skewness 3(n̂)> 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 3(n̂)>=-31±6 μK3 (Gaussian statistics assumed) or ±14 μK3 (including non-Gaussian corrections) in the filtered ACT data, a 5σ detection. We show that the skewness is a sensitive probe of σ8, and use analytic calculations and tSZ simulations to obtain cosmological constraints from this measurement. From this signal alone we infer a value of σ8=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. Disciplines Physical Sciences and Mathematics | Physics Comments Wilson, M. J., Sherwin, B. D. , Hill, J. C. , et al. (2012). Atacama Cosmology Telescope: A measurement of the thermal Sunyaev-Zel'dovich effect using the skewness of the CMB temperature distribution. Physical Review D, 86(12), 122005. doi: 10.1103/PhysRevD.86. 122005 ©2012 American Physical Society Author(s) Michael J. Wilson, Blake D. Sherwin, J. Colin Hill, Graeme Addison, Nick Battaglia, J. Richard Bond, Sudeep Das, Mark J. Devlin, Erik D. Reese, and Daniel S. Swetz This journal article is available at ScholarlyCommons: http://repository.upenn. edu/physics_papers/275 Atacama Cosmology Telescope: A measurement of the thermal Sunyaev-Zel’dovich effect using the skewness of the CMB temperature distribution Michael J. Wilson, Blake D. Sherwin,* J. Colin Hill, Graeme Addison, Nick Battaglia, J. Richard Bond, Sudeep Das, Mark J. Devlin, Joanna Dunkley, Rolando Dünner, Joseph W. Fowler, Megan B. Gralla, Amir Hajian, Mark Halpern, Matt Hilton, Adam D. Hincks, Renée 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, Suzanne T. Staggs, Daniel S. Swetz, Eric R. Switzer, Hy Trac, and Ed Wollack Department of Astrophysics, Oxford University, Oxford OX1 3RH, United Kingdom Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, New Jersey 08544, USA Department of Physics, Princeton University, Princeton, New Jersey 08544, USA Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario, Canada M5S 3H8 Berkeley Center for Cosmological Physics, Department of Physics, University of California, Berkeley, California 94720, USA Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA Departamento de Astronomı́a y Astrofı́sica, Pontificı́a Univ. Católica, Casilla 306, Santiago 22, Chile NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, Colorado 80305, USA Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218-2686, USA Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom Department of Physics, University of Miami, Coral Gables, Florida 33146, USA Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854-8019, USA Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Department of Physics, University of California, Santa Barbara, California 93106, USA Astrophysics and Cosmology Research Unit, University of KwaZulu-Natal, Durban 4041, South Africa Department of Physics and Astronomy, Haverford College, Haverford, Pennsylvania 19041, USA Kavli Institute for Cosmological Physics, 5620 South Ellis Avenue, Chicago, Illinois 60637, USA Code 553/665, NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771, USA (Received 5 April 2012; published 20 December 2012) We present a detection of the unnormalized skewness h ~ T3ðn̂Þi induced by the thermal SunyaevZel’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 (tSZnull) ACT maps. We measure h ~ T3ðn̂Þi 1⁄4 31 6 K (Gaussian statistics assumed) or 14 K (including non-Gaussian corrections) in the filtered ACT data, a 5 detection. We show that the skewness is a sensitive probe of 8, and use analytic calculations and tSZ simulations to obtain cosmological constraints from this measurement. From this signal alone we infer a value of 8 1⁄4 0:79þ0:03 0:03 (68% C.L.) þ0:06 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. DOI: 10.1103/PhysRevD.86. 122005 PACS numbers: 98.70. Vc