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Relativity and Gravitation Group

Dr Toshiya Namikawa

Career

  • 2019 - Now : Senior Research Associate, DAMTP, University of Cambridge
  • 2018 - 2018: Assistant Researcher (termed Assistant Professor), National Taiwan Univeristy
  • 2014 - 2017: Postdoctoral Researcher (with JSPS fellowship for two years), KIPAC, Stanford University
  • 2013 - 2014: Postdoctoral Researcher, Yukawa Institute for Theoretical Physics, Kyoto University
  • 2010 - 2013: PhD Student, University of Tokyo
  • 2008 - 2010: Master Student, University of Tokyo

Research

Toshiya is a member of the Department of Applied Mathematics and Theoretical Physics, in the Relativity and Gravitation research group. He is working on data-driven cosmology, the intersection between theoretical and observational cosmology. His current interests include B-mode analysis, gravitational lensing of CMB, cosmic birefringence, reionization and non-Gaussianity. He is an active member of several CMB experiments. 

 

Selected Publications

  • T. Namikawa et al. (ACTPol Collaboration), "The Atacama Cosmology Telescope: Constraints on Cosmic Birefringence", Phys. Rev. D, 101, 10465, 2020, arXiv:2001.10465
  • T. Namikawa et al. (POLARBEAR and Subaru-HSC Collaborations), "Evidence for the Cross-correlation between Cosmic Microwave Background Polarization Lensing from POLARBEAR and Cosmic Shear from Subaru Hyper Suprime-Cam", Astrophys. J., 882, 12, 2019, arXiv:1904.02116
  • BICEP2/Keck Array Collaborations, "BICEP2 / Keck Array X: Improved Constraints on Inflationary Gravitational Waves using BICEP2/Keck Data up to the 2015 Season in Conjunction with WMAP/Planck", Phys. Rev. Lett., 121, 221301, 2018, arXiv:1810.05216
  • T. Namikawa, "CMB internal delensing with general optimal estimator for higher-order correlations", Phys. Rev. D, 95, 103514, 2017, arXiv:1703.00169
  • BICEP2/Keck Array Collaborations, "BICEP2 / Keck Array IX: New Bounds on Anisotropies of CMB Polarization Rotation and Implications for Axion-Like Particles and Primordial Magnetic Fields", Phys. Rev. D, 96, 102003, 2017, arXiv:1705.02523
  • BICEP2/Keck Array Collaborations, "BICEP2 / Keck Array VIII: Measurement of Gravitational Lensing from Large-Scale B-mode Polarization", Astrophys. J., 833, 228, 2016, arXiv:1606.01968
  • T. Namikawa, "CMB Lensing bispectrum from Nonlinear Growth of the Large Scale Structure", Phys. Rev. D Rapid Communications, 93, 121301, 2016, arXiv:1604.08578
  • T. Namikawa et al., "Anisotropies of gravitational-wave standard sirens as a new cosmological probe without redshift information", Phys. Rev. Lett., 116, 0121302, 2016, arXiv:1511.04638
  • T. Namikawa et al.. "Bias-Hardened CMB Lensing", Mon. Not. R. Astron. Soc., 431, 609, 2013, arXiv:1209.0091
  • T. Namikawa et al., "Full-sky lensing reconstruction of gradient and curl modes from CMB maps", J. Cosmol. Astropart. Phys., 01, 007, 2012, arXiv:1110.1718

Publications

CMB-S4 Science Case, Reference Design, and Project Plan
K Abazajian, G Addison, P Adshead, Z Ahmed, SW Allen, D Alonso, M Alvarez, A Anderson, KS Arnold, C Baccigalupi, K Bailey, D Barkats, D Barron, PS Barry, JG Bartlett, RB Thakur, N Battaglia, E Baxter, R Bean, C Bebek, AN Bender, BA Benson, E Berger, S Bhimani, CA Bischoff, L Bleem, S Bocquet, K Boddy, M Bonato, JR Bond, J Borrill, FR Bouchet, ML Brown, S Bryan, B Burkhart, V Buza, K Byrum, E Calabrese, V Calafut, R Caldwell, JE Carlstrom, J Carron, T Cecil, A Challinor, CL Chang, Y Chinone, H-MS Cho, A Cooray, TM Crawford, A Crites, A Cukierman, F-Y Cyr-Racine, TD Haan, GD Zotti, J Delabrouille, M Demarteau, M Devlin, ED Valentino, M Dobbs, S Duff, A Duivenvoorden, C Dvorkin, W Edwards, J Eimer, J Errard, T Essinger-Hileman, G Fabbian, C Feng, S Ferraro, JP Filippini, R Flauger, B Flaugher, AA Fraisse, A Frolov, N Galitzki, S Galli, K Ganga, M Gerbino, M Gilchriese, V Gluscevic, D Green, D Grin, E Grohs, R Gualtieri, V Guarino, JE Gudmundsson, S Habib, G Haller, M Halpern, NW Halverson, S Hanany, K Harrington, M Hasegawa, M Hasselfield, M Hazumi, K Heitmann, S Henderson, JW Henning, JC Hill, R Hlozek, G Holder, W Holzapfel, J Hubmayr, KM Huffenberger, M Huffer, H Hui, K Irwin, BR Johnson, D Johnstone, WC Jones, K Karkare, N Katayama, J Kerby, S Kernovsky, R Keskitalo, T Kisner, L Knox, A Kosowsky, J Kovac, ED Kovetz, S Kuhlmann, C-L Kuo, N Kurita, A Kusaka, A Lahteenmaki, CR Lawrence, AT Lee, A Lewis, D Li, E Linder, M Loverde, A Lowitz, MS Madhavacheril, A Mantz, F Matsuda, P Mauskopf, J McMahon, M McQuinn, PD Meerburg, J-B Melin, J Meyers, M Millea, J Mohr, L Moncelsi, T Mroczkowski, S Mukherjee, M Münchmeyer, D Nagai, J Nagy, T Namikawa, F Nati, T Natoli, M Negrello, L Newburgh, MD Niemack, H Nishino, M Nordby, V Novosad, P O'Connor, G Obied, S Padin, S Pandey, B Partridge, E Pierpaoli, L Pogosian, C Pryke, G Puglisi, B Racine, S Raghunathan, A Rahlin, S Rajagopalan, M Raveri, M Reichanadter, CL Reichardt, M Remazeilles, G Rocha, NA Roe, A Roy, J Ruhl, M Salatino, B Saliwanchik, E Schaan, A Schillaci, MM Schmittfull, D Scott, N Sehgal, S Shandera, C Sheehy, BD Sherwin, E Shirokoff, SM Simon, A Slosar, R Somerville, D Spergel, ST Staggs, A Stark, R Stompor, KT Story, C Stoughton, A Suzuki, O Tajima, GP Teply, K Thompson, P Timbie, M Tomasi, JI Treu, M Tristram, G Tucker, C Umiltà, AV Engelen, JD Vieira, AG Vieregg, M Vogelsberger, G Wang, S Watson, M White, N Whitehorn, EJ Wollack, WLK Wu, Z Xu, S Yasini, J Yeck, KW Yoon, E Young, A Zonca
(2019)
(link to publication)
CMB-HD: An Ultra-Deep, High-Resolution Millimeter-Wave Survey Over Half the Sky
N Sehgal, S Aiola, Y Akrami, K Basu, M Boylan-Kolchin, S Bryan, S Clesse, F-Y Cyr-Racine, LD Mascolo, S Dicker, T Essinger-Hileman, S Ferraro, GM Fuller, D Han, M Hasselfield, G Holder, B Jain, B Johnson, M Johnson, P Klaassen, M Madhavacheril, P Mauskopf, D Meerburg, J Meyers, T Mroczkowski, M Munchmeyer, S Naess, D Nagai, T Namikawa, L Newburgh, HN Nguyen, M Niemack, BD Oppenheimer, E Pierpaoli, E Schaan, A Slosar, D Spergel, E Switzer, AV Engelen, E Wollack
– Bulletin of the American Astronomical Society, Vol. 51, Issue 7, id. 6 (2019)
(2019)
(link to publication)
CMB lensing bispectrum: Assessing analytical predictions against full-sky lensing simulations
T Namikawa, B Bose, FR Bouchet, R Takahashi, A Taruya
– Physical Review D
(2019)
99,
063511
(doi: 10.1103/physrevd.99.063511)
LiteBIRD: A Satellite for the Studies of B-Mode Polarization and Inflation from Cosmic Background Radiation Detection
M Hazumi, PAR Ade, Y Akiba, D Alonso, K Arnold, J Aumont, C Baccigalupi, D Barron, S Basak, S Beckman, J Borrill, F Boulanger, M Bucher, E Calabrese, Y Chinone, S Cho, A Cukierman, DW Curtis, T de Haan, M Dobbs, A Dominjon, T Dotani, L Duband, A Ducout, J Dunkley, JM Duval, T Elleflot, HK Eriksen, J Errard, J Fischer, T Fujino, T Funaki, U Fuskeland, K Ganga, N Goeckner-Wald, J Grain, NW Halverson, T Hamada, T Hasebe, M Hasegawa, K Hattori, M Hattori, L Hayes, N Hidehira, CA Hill, G Hilton, J Hubmayr, K Ichiki, T Iida, H Imada, M Inoue, Y Inoue, KD Irwin, H Ishino, O Jeong, H Kanai, D Kaneko, S Kashima, N Katayama, T Kawasaki, SA Kernasovskiy, R Keskitalo, A Kibayashi, Y Kida, K Kimura, T Kisner, K Kohri, E Komatsu, K Komatsu, CL Kuo, NA Kurinsky, A Kusaka, A Lazarian, AT Lee, D Li, E Linder, B Maffei, A Mangilli, M Maki, T Matsumura, S Matsuura, D Meilhan, S Mima, Y Minami, K Mitsuda, L Montier, M Nagai, T Nagasaki, R Nagata, M Nakajima, S Nakamura, T Namikawa, M Naruse, H Nishino, T Nitta, T Noguchi, H Ogawa, S Oguri, N Okada, A Okamoto
– Journal of Low Temperature Physics
(2019)
194,
443
(doi: 10.1007/s10909-019-02150-5)
Impact of nonlinear growth of the large-scale structure on CMB B -mode delensing
T Namikawa, R Takahashi
– Physical Review D
(2019)
99,
023530
(doi: 10.1103/PhysRevD.99.023530)
Effect of non-Gaussian lensing deflections on CMB lensing measurements
V Böhm, BD Sherwin, J Liu, JC Hill, M Schmittfull, T Namikawa
– Physical Review D
(2018)
98,
123510
(doi: 10.1103/PhysRevD.98.123510)
Constraints on Primordial Gravitational Waves Using Planck, WMAP, and New BICEP2/Keck Observations through the 2015 Season
PAR Ade, Z Ahmed, RW Aikin, KD Alexander, D Barkats, SJ Benton, CA Bischoff, JJ Bock, R Bowens-Rubin, JA Brevik, I Buder, E Bullock, V Buza, J Connors, J Cornelison, BP Crill, M Crumrine, M Dierickx, L Duband, C Dvorkin, JP Filippini, S Fliescher, J Grayson, G Hall, M Halpern, S Harrison, SR Hildebrandt, GC Hilton, H Hui, KD Irwin, J Kang, KS Karkare, E Karpel, JP Kaufman, BG Keating, S Kefeli, SA Kernasovskiy, JM Kovac, CL Kuo, NA Larsen, K Lau, EM Leitch, M Lueker, KG Megerian, L Moncelsi, T Namikawa, CB Netterfield, HT Nguyen, R O'Brient, RW Ogburn, S Palladino, C Pryke, B Racine, S Richter, A Schillaci, R Schwarz, CD Sheehy, A Soliman, T St Germaine, ZK Staniszewski, B Steinbach, RV Sudiwala, GP Teply, KL Thompson, JE Tolan, C Tucker, AD Turner, C Umiltà, AG Vieregg, A Wandui, AC Weber, DV Wiebe, J Willmert, CL Wong, WLK Wu, H Yang, KW Yoon, C Zhang, <i>Keck</i> Array and <span class="sc">bicep</span>2 Collaborations
– Physical Review Letters
(2018)
121,
221301
(doi: 10.1103/physrevlett.121.221301)
CMB lensing bispectrum as a probe of modified gravity theories
T Namikawa, FR Bouchet, A Taruya
– Physical Review D
(2018)
98,
043530
(doi: 10.1103/physrevd.98.043530)
Measurements of Degree-Scale B-mode Polarization with the BICEP/Keck Experiments at South Pole
TBICEPK Collaboration, PAR Ade, Z Ahmed, RW Aikin, KD Alexander, D Barkats, SJ Benton, CA Bischoff, JJ Bock, H Boenish, R Bowens-Rubin, JA Brevik, I Buder, E Bullock, V Buza, J Connors, J Cornelison, BP Crill, M Crumrine, M Dierickx, L Duband, C Dvorkin, JP Filippini, SFJ Grayson, G Hall, M Halpern, S Harrison, SR Hildebrandt, GC Hilton, H Hui, KD Irwin, J Kang, KS Karkare, E Karpel, JP Kaufman, BG Keating, S Kefeli, SA Kernasovskiy, JM Kovac, CL Kuo, K Lau, NA Larsen, EM Leitch, M Lueker, KG Megerian, L Moncelsi, T Namikawa, B Netterfield, HT Nguyen, R O'Brient, RWO IV, S Palladino, C Pryke, B Racine, S Richter, R Schwarz, A Schillaci, CD Sheehy, A Soliman, TS Germaine, ZK Staniszewski, B Steinbach, RV Sudiwala, GP Teply, KL Thompson, JE Tolan, C Tucker, AD Turner, C Umilta, AG Vieregg, A Wandui, AC Weber, DV Wiebe, J Willmert, CL Wong, WLK Wu, H Yang, KW Yoon, C Zhang
(2018)
(link to publication)
Concept Study of Optical Configurations for High-Frequency Telescope for LiteBIRD
T Hasebe, S Kashima, PAR Ade, Y Akiba, D Alonso, K Arnold, J Aumont, C Baccigalupi, D Barron, S Basak, S Beckman, J Borrill, F Boulanger, M Bucher, E Calabrese, Y Chinone, HM Cho, A Cukierman, DW Curtis, T de Haan, M Dobbs, A Dominjon, T Dotani, L Duband, A Ducout, J Dunkley, JM Duval, T Elleflot, HK Eriksen, J Errard, J Fischer, T Fujino, T Funaki, U Fuskeland, K Ganga, N Goeckner-Wald, J Grain, NW Halverson, T Hamada, M Hasegawa, K Hattori, M Hattori, L Hayes, M Hazumi, N Hidehira, CA Hill, G Hilton, J Hubmayr, K Ichiki, T Iida, H Imada, M Inoue, Y Inoue, KD Irwin, H Ishino, O Jeong, H Kanai, D Kaneko, N Katayama, T Kawasaki, SA Kernasovskiy, R Keskitalo, A Kibayashi, Y Kida, K Kimura, T Kisner, K Kohri, E Komatsu, K Komatsu, CL Kuo, NA Kurinsky, A Kusaka, A Lazarian, AT Lee, D Li, E Linder, B Maffei, A Mangilli, M Maki, T Matsumura, S Matsuura, D Meilhan, S Mima, Y Minami, K Mitsuda, L Montier, M Nagai, T Nagasaki, R Nagata, M Nakajima, S Nakamura, T Namikawa, M Naruse, H Nishino, T Nitta, T Noguchi, H Ogawa, S Oguri, N Okada, A Okamoto
– Journal of Low Temperature Physics
(2018)
193,
841
(doi: 10.1007/s10909-018-1915-2)
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Research Group

Relativity and Gravitation

Email

tn334@damtp.cam.ac.uk

Room

B1.09

Telephone

01223 337843

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