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The Atacama Cosmology Telescope: delensed power spectra and parameters

Han, Dongwon and Sehgal, Neelima and MacInnis, Amanda and van Engelen, Alexander and Sherwin, Blake D. and Madhavacheril, Mathew S. and Aiola, Simone and Battaglia, Nicholas and Beall, James A. and Becker, Daniel T. and Calabrese, Erminia and Choi, Steve K. and Darwish, Omar and Denison, Edward V. and Devlin, Mark J. and Dunkley, Jo and Ferraro, Simone and Fox, Anna E. and Hasselfield, Matthew and Hill, J. Colin and Hilton, Gene C. and Hilton, Matt and Hložek, Renée and Hubmayr, Johannes and Hughes, John P. and Kosowsky, Arthur and Van Lanen, Jeff and Louis, Thibaut and Moodley, Kavilan and Naess, Sigurd and Namikawa, Toshiya and Nati, Federico and Nibarger, John P. and Niemack, Michael D. and Page, Lyman A. and Partridge, Bruce and Qu, Frank J. and Schillaci, Alessandro and Spergel, David N. and Staggs, Suzanne and Storer, Emilie and Wollack, Edward J. (2021) The Atacama Cosmology Telescope: delensed power spectra and parameters. Journal of Cosmology and Astroparticle Physics, 2021 (1). Art. No. 031. ISSN 1475-7516. doi:10.1088/1475-7516/2021/01/031.

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We present ΛCDM cosmological parameter constraints obtained from delensed microwave background power spectra. Lensing maps from a subset of DR4 data from the Atacama Cosmology Telescope (ACT) are used to undo the lensing effect in ACT spectra observed at 150 and 98 GHz. At 150 GHz, we remove the lensing distortion with an effective efficiency of (TT), (EE), (TE) and (BB); this results in detections of the delensing effect at (TT), (EE), (TE), and (BB) significance. The combination of 150 and 98 GHz TT, EE, and TE delensed spectra is well fit by a standard ΛCDM model. We also measure the shift in best-fit parameters when fitting delensed versus lensed spectra; while this shift does not inform our ability to measure cosmological parameters, it does provide a three-way consistency check among the lensing inferred from the best-fit parameters, the lensing in the CMB power spectrum, and the reconstructed lensing map. This shift is predicted to be zero when fitting with the correct model since both lensed and delensed spectra originate from the same region of sky. Fitting with a ΛCDM model and marginalizing over foregrounds, we find that the shift in cosmological parameters is consistent with zero. Our results show that gravitational lensing of the microwave background is internally consistent within the framework of the standard cosmological model.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Sehgal, Neelima0000-0002-9674-4527
Madhavacheril, Mathew S.0000-0001-6740-5350
Aiola, Simone0000-0002-1035-1854
Battaglia, Nicholas0000-0001-5846-0411
Choi, Steve K.0000-0002-9113-7058
Devlin, Mark J.0000-0002-3169-9761
Ferraro, Simone0000-0003-4992-7854
Hill, J. Colin0000-0002-9539-0835
Hilton, Gene C.0000-0003-4247-467X
Hilton, Matt0000-0002-8490-8117
Hubmayr, Johannes0000-0002-2781-9302
Hughes, John P.0000-0002-8816-6800
Kosowsky, Arthur0000-0002-3734-331X
Moodley, Kavilan0000-0001-6606-7142
Naess, Sigurd0000-0002-4478-7111
Namikawa, Toshiya0000-0003-3070-9240
Nati, Federico0000-0002-8307-5088
Niemack, Michael D.0000-0001-7125-3580
Page, Lyman A.0000-0002-9828-3525
Partridge, Bruce0000-0001-6541-9265
Schillaci, Alessandro0000-0002-0512-1042
Spergel, David N.0000-0002-5151-0006
Staggs, Suzanne0000-0002-7020-7301
Wollack, Edward J.0000-0002-7567-4451
Additional Information:© 2021 IOP Publishing Ltd and Sissa Medialab. Received 31 July 2020; Accepted 13 November 2020; Published 18 January 2021. The authors would like to thank Joel Meyers for discussion regarding modifications to the theory code in Ref [14] that we performed. DH, NS, and AM acknowledge support from NSF grant numbers AST-1513618 and AST-1907657. EC acknowledges support from the STFC Ernest Rutherford Fellowship ST/M004856/2 and STFC Consolidated Grant ST/S00033X/1, and from the Horizon 2020 ERC Starting Grant (Grant agreement No 849169). MSM acknowledges support from NSF grant AST-1814971. KM and MH acknowledges support from the National Research Foundation of South Africa. This work was supported by the U.S. National Science Foundation through awards AST-0408698, AST-0965625, and AST-1440226 for the ACT project, as well as awards PHY-0855887 and PHY-1214379. Funding was also provided by Princeton University, the University of Pennsylvania, and a Canada Foundation for Innovation (CFI) award to UBC. ACT operates in the Parque Astronómico Atacama in northern Chile under the auspices of the Comisión Nacional de Investigación Cientıfica y Tecnológica de Chile (CONICYT). Computations were performed on the GPC supercomputer at the SciNet HPC Consortium. SciNet is funded by the CFI under the auspices of Compute Canada, the Government of Ontario, the Ontario Research Fund - Research Excellence; and the University of Toronto. This research also used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. In addition, computations were performed on the supercomputers provided by the Center for Computational Astrophysics at the Flatiron Institute. The Flatiron Institute is supported by the Simons Foundation. The development of multichroic detectors and lenses was supported by NASA grants NNX13AE56G and NNX14AB58G. We thank our many colleagues from ABS, ALMA, APEX, and Polarbear who have helped us at critical junctures. Colleagues at AstroNorte and RadioSky provide logistical support and keep operations in Chile running smoothly. We also thank the Mishrahi Fund and the Wilkinson Fund for their generous support of the project.
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)ST/M004856/2
Science and Technology Facilities Council (STFC)ST/S00033X/1
European Research Council (ERC)849169
National Research Foundation (South Africa)UNSPECIFIED
Princeton UniversityUNSPECIFIED
University of PennsylvaniaUNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)UNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Government of OntarioUNSPECIFIED
Ontario Research Fund-Research ExcellenceUNSPECIFIED
University of TorontoUNSPECIFIED
Department of Energy (DOE)DE-AC02-05CH11231
Simons FoundationUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20210120-133355611
Persistent URL:
Official Citation:Dongwon Han et al JCAP01(2021)031
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107596
Deposited By: Tony Diaz
Deposited On:20 Jan 2021 21:55
Last Modified:16 Nov 2021 19:04

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