Browsing by Author "Zhu, Ningfeng"

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    The Atacama Cosmology Telescope: a measurement of the Cosmic Microwave Background power spectra at 98 and 150 GHz
    (2020) Choi, Steve K.; Hasselfield, Matthew; Ho, Shuay-Pwu Patty; Koopman, Brian; Lungu, Marius; Abitbol, Maximilian H.; Addison, Graeme E.; Ade, Peter A. R.; Aiola, Simone; Alonso, David; Amiri, Mandana; Amodeo, Stefania; Angile, Elio; Austermann, Jason E.; Baildon, Taylor; Battaglia, Nick; Beall, James A.; Bean, Rachel; Becker, Daniel T.; Bond, J. Richard; Bruno, Sarah Marie; Calabrese, Erminia; Calafut, Victoria; Campusano, Luis E.; Carrero, Felipe; Chesmore, Grace E.; Cho, Hsiao-mei; Clark, Susan E.; Cothard, Nicholas F.; Crichton, Devin; Crowley, Kevin T.; Darwish, Omar; Datta, Rahul; Denison, Edward, V; Devlin, Mark J.; Duell, Cody J.; Duff, Shannon M.; Duivenvoorden, Adriaan J.; Dunkley, Jo; Dunner, Rolando; Essinger-Hileman, Thomas; Fankhanel, Max; Ferraro, Simone; Fox, Anna E.; Fuzia, Brittany; Gallardo, Patricio A.; Gluscevic, Vera; Golec, Joseph E.; Grace, Emily; Gralla, Megan; Guan, Yilun; Hall, Kirsten; Halpern, Mark; Han, Dongwon; Hargrave, Peter; Henderson, Shawn; Hensley, Brandon; Hill, J. Colin; Hilton, Gene C.; Hilton, Matt; Hincks, Adam D.; Hlozek, Renee; Hubmayr, Johannes; Huffenberger, Kevin M.; Hughes, John P.; Infante, Leopoldo; Irwin, Kent; Jackson, Rebecca; Klein, Jeff; Knowles, Kenda; Kosowsky, Arthur; Lakey, Vincent; Li, Dale; Li, Yaqiong; Li, Zack; Lokken, Martine; Louis, Thibaut; MacInnis, Amanda; Madhavacheril, Mathew; Maldonado, Felipe; Mallaby-Kay, Maya; Marsden, Danica; Maurin, Loic; McMahon, Jeff; Menanteau, Felipe; Moodley, Kavilan; Morton, Tim; Naess, Sigurd; Namikawa, Toshiya; Nati, Federico; Newburgh, Laura; Nibarger, John P.; Nicola, Andrina; Niemack, Michael D.; Nolta, Michael R.; Orlowski-Sherer, John; Page, Lyman A.; Pappas, Christine G.; Partridge, Bruce; Phakathi, Phumlani; Prince, Heather; Puddu, Roberto; Qu, Frank J.; Rivera, Jesus; Robertson, Naomi; Rojas, Felipe; Salatino, Maria; Schaan, Emmanuel; Schillaci, Alessandro; Schmitt, Benjamin L.; Sehgal, Neelima; Sherwin, Blake D.; Sierra, Carlos; Sievers, Jon; Sifon, Cristobal; Sikhosana, Precious; Simon, Sara; Spergel, David N.; Staggs, Suzanne T.; Stevens, Jason; Storer, Emilie; Sunder, Dhaneshwar D.; Switzer, Eric R.; Thorne, Ben; Thornton, Robert; Trac, Hy; Treu, Jesse; Tucker, Carole; Vale, Leila R.; Van Engelen, Alexander; Van Lanen, Jeff; Vavagiakis, Eve M.; Wagoner, Kasey; Wang, Yuhan; Ward, Jonathan T.; Wollack, Edward J.; Xu, Zhilei; Zago, Fernando; Zhu, Ningfeng
    We present the temperature and polarization angular power spectra of the CMB measured by the Atacama Cosmology Telescope (ACT) from 5400 deg(2) of the 2013-2016 survey, which covers >15000 deg(2) at 98 and 150 GHz. For this analysis we adopt a blinding strategy to help avoid confirmation bias and, related to this, show numerous checks for systematic error done before unblinding. Using the likelihood for the cosmological analysis we constrain secondary sources of anisotropy and foreground emission, and derive a "CMB-only" spectrum that extends to l = 4000. At large angular scales, foreground emission at 150 GHz is similar to 1% of TT and EE within our selected regions and consistent with that found by Planck. Using the same likelihood, we obtain the cosmological parameters for Lambda CDM for the ACT data alone with a prior on the optical depth of tau = 0.065 +/- 0.015. Lambda CDM is a good fit. The best-fit model has a reduced chi(2) of 1.07 (PTE = 0.07) with H-0 = 67.9 +/- 1.5 km/s/Mpc. We show that the lensing BB signal is consistent with Lambda CDM and limit the celestial EB polarization angle to psi(P) = 0.07 degrees +/- 0.09 degrees. We directly cross correlate ACT with Planck and observe generally good agreement but with some discrepancies in TE. All data on which this analysis is based will be publicly released.
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    The Atacama Cosmology Telescope: DR4 maps and cosmological parameters
    (2020) Aiola, Simone; Calabrese, Erminia; Maurin, Loic; Naess, Sigurd; Schmitt, Benjamin L.; Abitbol, Maximilian H.; Addison, Graeme E.; Ade, Peter A. R.; Alonso, David; Amiri, Mandana; Amodeo, Stefania; Angile, Elio; Austermann, Jason E.; Baildon, Taylor; Battaglia, Nick; Beall, James A.; Bean, Rachel; Becker, Daniel T.; Bond, J. Richard; Bruno, Sarah Marie; Calafut, Victoria; Campusano, Luis E.; Carrero, Felipe; Chesmore, Grace E.; Cho, Hsiao-mei; Choi, Steve K.; Clark, Susan E.; Cothard, Nicholas F.; Crichton, Devin; Crowley, Kevin T.; Darwish, Omar; Datta, Rahul; Denison, Edward, V; Devlin, Mark J.; Duell, Cody J.; Duff, Shannon M.; Duivenvoorden, Adriaan J.; Dunkley, Jo; Dunner, Rolando; Essinger-Hileman, Thomas; Fankhanel, Max; Ferraro, Simone; Fox, Anna E.; Fuzia, Brittany; Gallardo, Patricio A.; Gluscevic, Vera; Golec, Joseph E.; Grace, Emily; Gralla, Megan; Guan, Yilun; Hall, Kirsten; Halpern, Mark; Han, Dongwon; Hargrave, Peter; Hasselfield, Matthew; Helton, Jakob M.; Henderson, Shawn; Hensley, Brandon; Hill, J. Colin; Hilton, Gene C.; Hilton, Matt; Hincks, Adam D.; Hlozek, Renee; Ho, Shuay-Pwu Patty; Hubmayr, Johannes; Huffenberger, Kevin M.; Hughes, John P.; Infante, Leopoldo; Irwin, Kent; Jackson, Rebecca; Klein, Jeff; Knowles, Kenda; Koopman, Brian; Kosowsky, Arthur; Lakey, Vincent; Li, Dale; Li, Yaqiong; Li, Zack; Lokken, Martine; Louis, Thibaut; Lungu, Marius; MacInnis, Amanda; Madhavacheril, Mathew; Maldonado, Felipe; Mallaby-Kay, Maya; Marsden, Danica; McMahon, Jeff; Menanteau, Felipe; Moodley, Kavilan; Morton, Tim; Namikawa, Toshiya; Nati, Federico; Newburgh, Laura; Nibarger, John P.; Nicola, Andrina; Niemack, Michael D.; Nolta, Michael R.; Orlowski-Sherer, John; Page, Lyman A.; Pappas, Christine G.; Partridge, Bruce; Phakathi, Phumlani; Pisano, Giampaolo; Prince, Heather; Puddu, Roberto; Qu, Frank J.; Rivera, Jesus; Robertson, Naomi; Rojas, Felipe; Salatino, Maria; Schaan, Emmanuel; Schillaci, Alessandro; Sehgal, Neelima; Sherwin, Blake D.; Sierra, Carlos; Sievers, Jon; Sifon, Cristobal; Sikhosana, Precious; Simon, Sara; Spergel, David N.; Staggs, Suzanne T.; Stevens, Jason; Storer, Emilie; Sunder, Dhaneshwar D.; Switzer, Eric R.; Thorne, Ben; Thornton, Robert; Hy Trac; Treu, Jesse; Tucker, Carole; Vale, Leila R.; Van Engelen, Alexander; Van Lanen, Jeff; Vavagiakis, Eve M.; Wagoner, Kasey; Wang, Yuhan; Ward, Jonathan T.; Wollack, Edward J.; Xu, Zhilei; Zago, Fernando; Zhu, Ningfeng
    We present new arcminute-resolution maps of the Cosmic Microwave Background temperature and polarization anisotropy from the Atacama Cosmology Telescope, using data taken from 2013-2016 at 98 and 150 GHz. The maps cover more than 17,000 deg(2), the deepest 600 deg(2) with noise levels below 10 mu K-arcmin. We use the power spectrum derived from almost 6,000 deg(2) of these maps to constrain cosmology. The ACT data enable a measurement of the angular scale of features in both the divergence-like polarization and the temperature anisotropy, tracing both the velocity and density at last-scattering. From these one can derive the distance to the last-scattering surface and thus infer the local expansion rate, H-0. By combining ACT data with large-scale information from WMAP we measure H-0 = 67.6 +/- 1.1 km/s/Mpc, at 68% confidence, in excellent agreement with the independently-measured Planck satellite estimate (from ACT alone we find H-0 = 67.9 +/- 1.5 km/s/Mpc). The Lambda CDM model provides a good fit to the ACT data, and we find no evidence for deviations: both the spatial curvature, and the departure from the standard lensing signal in the spectrum, are zero to within 1 sigma; the number of relativistic species, the primordial Helium fraction, and the running of the spectral index are consistent with Lambda CDM predictions to within 1.5-2.2 sigma. We compare ACT, WMAP, and Planck at the parameter level and find good consistency; we investigate how the constraints on the correlated spectral index and baryon density parameters readjust when adding CMB large-scale information that ACT does not measure. The DR4 products presented here will be publicly released on the NASA Legacy Archive for Microwave Background Data Analysis.
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    The Simons Observatory Large Aperture Telescope Receiver
    (2021) Zhu, Ningfeng; Bhandarkar, Tanay; Coppi, Gabriele; Kofman, Anna M.; Orlowski-Scherer, John L.; Xu, Zhilei; Adachi, Shunsuke; Ade, Peter; Aiola, Simone; Austermann, Jason; Bazarko, Andrew O.; Beall, James A.; Bhimani, Sanah; Bond, J. Richard; Chesmore, Grace E.; Choi, Steve K.; Connors, Jake; Cothard, Nicholas F.; Devlin, Mark; Dicker, Simon; Dober, Bradley; Duell, Cody J.; Duff, Shannon M.; Dunner, Rolando; Fabbian, Giulio; Galitzki, Nicholas; Gallardo, Patricio A.; Golec, Joseph E.; Haridas, Saianeesh K.; Harrington, Kathleen; Healy, Erin; Ho, Shuay-Pwu Patty; Huber, Zachary B.; Hubmayr, Johannes; Iuliano, Jeffrey; Johnson, Bradley R.; Keating, Brian; Kiuchi, Kenji; Koopman, Brian J.; Lashner, Jack; Lee, Adrian T.; Li, Yaqiong; Limon, Michele; Link, Michael; Lucas, Tammy J.; McCarrick, Heather; Moore, Jenna; Nati, Federico; Newburgh, Laura B.; Niemack, Michael D.; Pierpaoli, Elena; Randall, Michael J.; Sarmiento, Karen Perez; Saunders, Lauren J.; Seibert, Joseph; Sierra, Carlos; Sonka, Rita; Spisak, Jacob; Sutariya, Shreya; Tajima, Osamu; Teply, Grant P.; Thornton, Robert J.; Tsan, Tran; Tucker, Carole; Ullom, Joel; Vavagiakis, Eve M.; Vissers, Michael R.; Walker, Samantha; Westbrook, Benjamin; Wollack, Edward J.; Zannoni, Mario
    The Simons Observatory is a ground-based cosmic microwave background experiment that consists of three 0.4 m small-aperture telescopes and one 6 m Large Aperture Telescope, located at an elevation of 5300 m on Cerro Toco in Chile. The Simons Observatory Large Aperture Telescope Receiver (LATR) is the cryogenic camera that will be coupled to the Large Aperture Telescope. The resulting instrument will produce arcminute-resolution millimeter-wave maps of half the sky with unprecedented precision. The LATR is the largest cryogenic millimeter-wave camera built to date, with a diameter of 2.4 m and a length of 2.6 m. The coldest stage of the camera is cooled to 100 mK, the operating temperature of the bolometric detectors with bands centered around 27, 39, 93, 145, 225, and 280 GHz. Ultimately, the LATR will accommodate 13 40 cm diameter optics tubes, each with three detector wafers and a total of 62,000 detectors. The LATR design must simultaneously maintain the optical alignment of the system, control stray light, provide cryogenic isolation, limit thermal gradients, and minimize the time to cool the system from room temperature to 100 mK. The interplay between these competing factors poses unique challenges. We discuss the trade studies involved with the design, the final optimization, the construction, and ultimate performance of the system.
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    The Simons Observatory: modeling optical systematics in the Large Aperture Telescope
    (2021) Gudmundsson, Jon E.; Gallardo, Patricio A.; Puddu, Roberto; Dicker, Simon R.; Adler, Alexandre E.; Ali, Aamir M.; Bazarko, Andrew; Chesmore, Grace E.; Coppi, Gabriele; Cothard, Nicholas F.; Dachlythra, Nadia; Devlin, Mark; Dunner, Rolando; Fabbian, Giulio; Galitzki, Nicholas; Golec, Joseph E.; Ho, Shuay-Pwu Patty; Hargrave, Peter C.; Kofman, Anna M.; Lee, Adrian T.; Limon, Michele; Matsuda, Frederick T.; Mauskopf, Philip D.; Moodley, Kavilan; Nati, Federico; Niemack, Michael D.; Orlowski-Scherer, John; Page, Lyman A.; Partridge, Bruce; Puglisi, Giuseppe; Reichardt, Christian L.; Sierra, Carlos E.; Simon, Sara M.; Teply, Grant P.; Tucker, Carole; Wollack, Edward J.; Xu, Zhilei; Zhu, Ningfeng
    We present geometrical and physical optics simulation results for the Simons Observatory Large Aperture Telescope. This work was developed as part of the general design process for the telescope, allowing us to evaluate the impact of various design choices on performance metrics and potential systematic effects. The primary goal of the simulations was to evaluate the final design of the reflectors and the cold optics that are now being built. We describe nonsequential ray tracing used to inform the design of the cold optics, including absorbers internal to each optics tube. We discuss ray tracing simulations of the telescope structure that allow us to determine geometries that minimize detector loading and mitigate spurious near-field effects that have not been resolved by the internal baffling. We also describe physical optics simulations, performed over a range of frequencies and field locations, that produce estimates of monochromatic far-field beam patterns, which in turn are used to gauge general optical performance. Finally, we describe simulations that shed light on beam sidelobes from panel gap diffraction. (C) 2021 Optical Society of America