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The Atacama Cosmology Telescope: A Search for Planet 9

Naess, Sigurd and Aiola, Simone and Battaglia, Nick and Bond, Richard J. and Calabrese, Erminia and Choi, Steve K. and Cothard, Nicholas F. and Halpern, Mark and Hill, J. Colin and Koopman, Brian J. and Devlin, Mark and McMahon, Jeff and Dicker, Simon and Duivenvoorden, Adriaan J. and Dunkley, Jo and Fanfani, Valentina and Ferraro, Simone and Gallardo, Patricio A. and Guan, Yilun and Han, Dongwon and Hasselfield, Matthew and Hincks, Adam D. and Huffenberger, Kevin and Kosowsky, Arthur B. and Louis, Thibaut and Macinnis, Amanda and Madhavacheril, Mathew S. and Nati, Federico and Niemack, Michael D. and Page, Lyman and Salatino, Maria and Schaan, Emmanuel and Orlowski-Scherer, John and Schillaci, Alessandro and Schmitt, Benjamin and Sehgal, Neelima and Sifón, Cristóbal and Staggs, Suzanne and Van Engelen, Alexander and Wollack, Edward J. (2021) The Atacama Cosmology Telescope: A Search for Planet 9. Astrophysical Journal, 923 (2). Art. No. 224. ISSN 0004-637X. doi:10.3847/1538-4357/ac2307.

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We use Atacama Cosmology Telescope (ACT) observations at 98 GHz (2015–2019), 150 GHz (2013–2019), and 229 GHz (2017–2019) to perform a blind shift-and-stack search for Planet 9. The search explores distances from 300 au to 2000 au and velocities up to 6 3 per year, depending on the distance (r). For a 5 Earth-mass Planet 9 the detection limit varies from 325 au to 625 au, depending on the sky location. For a 10 Earth-mass planet the corresponding range is 425 au to 775 au. The predicted aphelion and most likely location of the planet corresponds to the shallower end of these ranges. The search covers the whole 18,000 square degrees of the ACT survey. No significant detections are found, which is used to place limits on the millimeter-wave flux density of Planet 9 over much of its orbit. Overall we eliminate roughly 17% and 9% of the parameter space for a 5 and 10 Earth-mass Planet 9, respectively. These bounds approach those of a recent INPOP19a ephemeris-based analysis, but do not exceed it. We also provide a list of the 10 strongest candidates from the search for possible follow-up. More generally, we exclude (at 95% confidence) the presence of an unknown solar system object within our survey area brighter than 4–12 mJy (depending on position) at 150 GHz with current distance 300 au < r < 600 au and heliocentric angular velocity 1.’5/yr⁻¹ < v⋅500 AU/r < 2.”3 yr⁻¹, corresponding to low-to-moderate eccentricities. These limits worsen gradually beyond 600 au, reaching 5–15 mJy by 1500 au.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Naess, Sigurd0000-0002-4478-7111
Aiola, Simone0000-0002-1035-1854
Battaglia, Nick0000-0001-5846-0411
Bond, Richard J.0000-0003-2358-9949
Calabrese, Erminia0000-0003-0837-0068
Choi, Steve K.0000-0002-9113-7058
Cothard, Nicholas F.0000-0002-6151-6292
Halpern, Mark0000-0002-1760-0868
Hill, J. Colin0000-0002-9539-0835
Koopman, Brian J.0000-0003-0744-2808
Devlin, Mark0000-0002-3169-9761
McMahon, Jeff0000-0002-7245-4541
Dicker, Simon0000-0002-1940-4289
Duivenvoorden, Adriaan J.0000-0003-2856-2382
Dunkley, Jo0000-0002-7450-2586
Fanfani, Valentina0000-0003-2410-0922
Ferraro, Simone0000-0003-4992-7854
Gallardo, Patricio A.0000-0001-9731-3617
Guan, Yilun0000-0002-1697-3080
Han, Dongwon0000-0001-5649-3551
Hasselfield, Matthew0000-0002-2408-9201
Hincks, Adam D.0000-0003-1690-6678
Huffenberger, Kevin0000-0001-7109-0099
Kosowsky, Arthur B.0000-0002-3734-331X
Louis, Thibaut0000-0002-6849-4217
Madhavacheril, Mathew S.0000-0001-6740-5350
Nati, Federico0000-0002-8307-5088
Niemack, Michael D.0000-0001-7125-3580
Page, Lyman0000-0002-9828-3525
Salatino, Maria0000-0003-4006-1134
Schaan, Emmanuel0000-0002-4619-8927
Orlowski-Scherer, John0000-0003-1842-8104
Schillaci, Alessandro0000-0002-0512-1042
Sehgal, Neelima0000-0002-9674-4527
Sifón, Cristóbal0000-0002-8149-1352
Staggs, Suzanne0000-0002-7020-7301
Wollack, Edward J.0000-0002-7567-4451
Additional Information:© 2021. The American Astronomical Society. Received 2021 May 11; revised 2021 August 30; accepted 2021 August 31; published 2021 December 23. 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-0355328, 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 (CONICYT). Flatiron Institute is supported by the Simons Foundation. Computations were performed using Princeton Research Computing resources at Princeton University, the Niagara supercomputer at the SciNet HPC Consortium, and the Simons-Popeye cluster of the Flatiron Institute. 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. S.N. thanks Bruce Partridge for extensive comments. E.C. acknowledges support from the STFC Ernest Rutherford Fellowship ST/M004856/2 and STFC Consolidated Grant ST/S00033X/1, and from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 849169). Research at Perimeter Institute is supported in part by the Government of Canada through the Department of Innovation, Science and Industry Canada and by the Province of Ontario through the Ministry of Colleges and Universities. S.K.C. acknowledges support from NSF award AST-2001866. K.M.H. is supported by NSF through AST 1815887. N.S., D.H., and A.M. acknowledge support from NSF grant No. AST-1907657. We gratefully acknowledge the many publicly available software packages that were essential for parts of this analysis. They include healpy (Zonca et al. 2019), HEALPix (Górski et al. 2005), and pixell. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration 2013; Price-Whelan et al. 2018). We also acknowledge use of the matplotlib (Hunter 2007) package and the Python Image Library for producing plots in this paper.
Funding AgencyGrant Number
Princeton UniversityUNSPECIFIED
University of PennsylvaniaUNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)UNSPECIFIED
Simons FoundationUNSPECIFIED
Government of OntarioUNSPECIFIED
Ontario Research Fund-Research ExcellenceUNSPECIFIED
University of TorontoUNSPECIFIED
Science and Technology Facilities Council (STFC)ST/M004856/2
Science and Technology Facilities Council (STFC)ST/S00033X/1
European Research Council (ERC)849169
Department of Innovation, Science and Industry (Canada)UNSPECIFIED
Ontario Ministry of Colleges and UniversitiesUNSPECIFIED
Subject Keywords:Solar system planets; Millimeter astronomy; Sky surveys
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Solar system planets (1260); Millimeter astronomy (1061); Sky surveys (1464)
Record Number:CaltechAUTHORS:20220114-266136000
Persistent URL:
Official Citation:Sigurd Naess et al 2021 ApJ 923 224
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112931
Deposited By: George Porter
Deposited On:18 Jan 2022 23:23
Last Modified:18 Jan 2022 23:23

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