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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

Constraining higher-order parameters for primordial non-Gaussianities from power spectra and bispectra of imaging surveys
I Hashimoto, A Taruya, T Matsubara, T Namikawa, S Yokoyama
– Physical Review D
(2016)
93,
103537
(doi: 10.1103/physrevd.93.103537)
LiteBIRD: Mission Overview and Focal Plane Layout
T Matsumura, Y Akiba, K Arnold, J Borrill, R Chendra, Y Chinone, A Cukierman, T de Haan, M Dobbs, A Dominjon, T Elleflot, J Errard, T Fujino, H Fuke, N Goeckner-wald, N Halverson, P Harvey, M Hasegawa, K Hattori, M Hattori, M Hazumi, C Hill, G Hilton, W Holzapfel, Y Hori, J Hubmayr, K Ichiki, J Inatani, M Inoue, Y Inoue, F Irie, K Irwin, H Ishino, H Ishitsuka, O Jeong, K Karatsu, S Kashima, N Katayama, I Kawano, B Keating, A Kibayashi, Y Kibe, Y Kida, K Kimura, N Kimura, K Kohri, E Komatsu, CL Kuo, S Kuromiya, A Kusaka, A Lee, E Linder, H Matsuhara, S Matsuoka, S Matsuura, S Mima, K Mitsuda, K Mizukami, H Morii, T Morishima, M Nagai, T Nagasaki, R Nagata, M Nakajima, S Nakamura, T Namikawa, M Naruse, K Natsume, T Nishibori, K Nishijo, H Nishino, T Nitta, A Noda, T Noguchi, H Ogawa, S Oguri, IS Ohta, C Otani, N Okada, A Okamoto, A Okamoto, T Okamura, G Rebeiz, P Richards, S Sakai, N Sato, Y Sato, Y Segawa, S Sekiguchi, Y Sekimoto, M Sekine, U Seljak, B Sherwin, K Shinozaki, S Shu, R Stompor, H Sugai, H Sugita, T Suzuki, A Suzuki
– Journal of Low Temperature Physics
(2016)
184,
824
(doi: 10.1007/s10909-016-1542-8)
Anisotropies of Gravitational-Wave Standard Sirens as a New Cosmological Probe without Redshift Information
T Namikawa, A Nishizawa, A Taruya
– Physical review letters
(2016)
116,
121302
(doi: 10.1103/physrevlett.116.121302)
Delensing cosmic microwave background B modes with the Square Kilometre Array Radio Continuum Survey
T Namikawa, D Yamauchi, B Sherwin, R Nagata
– Physical Review D
(2016)
93,
043527
(doi: 10.1103/physrevd.93.043527)
Non-Gaussian structure of B-mode polarization after delensing
T Namikawa, R Nagata
– Journal of Cosmology and Astroparticle Physics
(2015)
2015,
004
(doi: 10.1088/1475-7516/2015/10/004)
Future detectability of gravitational-wave induced lensing from high-sensitivity CMB experiments
T Namikawa, D Yamauchi, A Taruya
– Physical Review D - Particles, Fields, Gravitation and Cosmology
(2015)
91,
043531
(doi: 10.1103/PhysRevD.91.043531)
Lensing reconstruction from a patchwork of polarization maps
T Namikawa, R Nagata
– Journal of Cosmology and Astroparticle Physics
(2014)
2014,
009
(doi: 10.1088/1475-7516/2014/09/009)
LiteBIRD: Mission overview and design tradeoffs
T Matsumura, Y Akiba, J Borrill, Y Chinone, M Dobbs, H Fuke, M Hasegawa, K Hattori, M Hattori, M Hazumi, W Holzapfel, Y Hori, J Inatani, M Inoue, Y Inoue, K Ishidoshiro, H Ishino, H Ishitsuka, K Karatsu, S Kashima, N Katayama, I Kawano, A Kibayashi, Y Kibe, K Kimura, N Kimura, E Komatsu, M Kozu, K Koga, A Lee, H Matsuhara, S Mima, K Mitsuda, K Mizukami, H Morii, T Morishima, M Nagai, R Nagata, S Nakamura, M Naruse, T Namikawa, K Natsume, T Nishibori, K Nishijo, H Nishino, A Noda, T Noguchi, H Ogawa, S Oguri, IS Ohta, N Okada, C Otani, P Richards, S Sakai, N Sato, Y Sato, Y Segawa, Y Sekimoto, K Shinozaki, H Sugita, A Suzuki, T Suzuki, O Tajima, S Takada, S Takakura, Y Takei, T Tomaru, Y Uzawa, T Wada, H Watanabe, Y Yamada, H Yamaguchi, N Yamasaki, M Yoshida, T Yoshida, K Yotsumoto
– Proceedings of SPIE--the International Society for Optical Engineering
(2014)
9143,
91431f-91431f-8
(doi: 10.1117/12.2055794)
Cosmology from weak lensing of CMB
T Namikawa
– Progress of Theoretical and Experimental Physics
(2014)
2014,
06b108
(doi: 10.1093/ptep/ptu044)
Detecting primordial non-Gaussianity from the three-point statistics of halo and weak lensing fields
I Hashimoto, A Taruya, S Yokoyama, T Namikawa, T Matsubara
– JGRG 2014 - Proceedings of the 24th Workshop on General Relativity and Gravitation in Japan
(2014)
4,
621
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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