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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

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
– Phys Rev Lett
(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)
The LiteBIRD Satellite Mission: Sub-Kelvin Instrument
A Suzuki, 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, B Crill, 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, 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, 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
– Journal of Low Temperature Physics
(2018)
193,
1048
(doi: 10.1007/s10909-018-1947-7)
Constraints on patchy reionization from Planck CMB temperature trispectrum
T Namikawa
– Physical Review D
(2018)
97,
063505
(doi: 10.1103/physrevd.97.063505)
Concept design of the LiteBIRD satellite for CMB B-mode polarization
Y Sekimoto, P Ade, K Arnold, J Aumont, J Austermann, C Baccigalupi, A Banday, R Banerji, S Basak, S Beckman, M Bersanelli, J Borrill, F Boulanger, ML Brown, M Bucher, E Calabrese, FJ Casas, A Challinor, Y Chinone, F Columbro, A Cukierman, D Curtis, P De Bernardis, M De Petris, M Dobbs, T Dotani, L Duband, JM Duval, A Ducout, K Ebisawa, T Elleot, H Eriksen, J Errard, R Flauger, C Franceschet, U Fuskeland, K Ganga, RJ Gao, T Ghigna, J Grain, A Gruppuso, N Halverson, P Hargrave, T Hasebe, M Hasegawa, M Hattori, M Hazumi, S Henrot-Versille, C Hill, Y Hirota, E Hivon, TD Hoang, J Hubmayr, K Ichiki, H Imada, H Ishino, G Jaehnig, H Kanai, S Kashima, Y Kataoka, N Katayama, T Kawasaki, R Keskitalo, A Kibayashi, T Kikuchi, K Kimura, T Kisner, Y Kobayashi, N Kogiso, K Kohri, E Komatsu, K Komatsu, K Konishi, N Krachmalnicoff, LC Kuo, N Kurinsky, A Kushino, L Lamagna, TA Lee, E Linder, B Maffei, M Maki, A Mangilli, E Martinez-Gonzalez, S Masi, T Matsumura, A Mennella, Y Minami, K Mistuda, D Molinari, L Montier, G Morgante, B Mot, Y Murata, A Murphy, M Nagai, R Nagata, S Nakamura, T Namikawa, P Natoli
– SPACE TELESCOPES AND INSTRUMENTATION 2018: OPTICAL, INFRARED, AND MILLIMETER WAVE
(2018)
10698,
106981y
(doi: 10.1117/12.2313432)
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Research Group

Relativity and Gravitation

Email

tn334@damtp.cam.ac.uk

Room

B1.09

Telephone

01223 337843

Study at Cambridge

About the University

Research at Cambridge