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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

Thermal testing for cryogenic CMB instrument optical design
DC Goldfinger, PAR Ade, Z Ahmed, M Amiri, D Barkats, R Basu Thakur, D Beck, CA Bischoff, JJ Bock, V Buza, J Cheshire, J Connors, J Cornelison, M Crumrine, AJ Cukierman, EV Denison, MI Dierickx, L Duband, M Eiben, S Fatigoni, JP Filippini, C Giannakopoulos, N Goeckner-Wald, J Grayson, PK Grimes, G Hall, G Halal, M Halpern, E Hand, SA Harrison, S Henderson, SR Hildebrandt, GC Hilton, J Hubmayr, H Hui, KD Irwin, J Kang, KS Karkare, S Kefeli, JM Kovac, CL Kuo, K Lau, EM Leitch, A Lennox, T Liu, KG Megerian, L Minutolo, L Moncelsi, Y Nakato, T Namikawa, HT Nguyen, R O'Brient, S Palladino, MA Petroff, T Prouve, C Pryke, B Racine, CD Reintsema, M Salatino, A Schillaci, BL Schmitt, B Singari, A Soliman, AG Smith, T St. Germaine, B Steinbach, RV Sudiwala, KL Thompson, C Tsai, C Tucker, AD Turner, C Umilta, C Vergès, AG Vieregg, A Wandui, AC Weber, DV Wiebe, J Willmert, WLK Wu, H Yang, KW Yoon, E Young, C Yu, L Zeng, C Zhang, S Zhang
– Proceedings of SPIE--the International Society for Optical Engineering
(2022)
12190,
126
(doi: 10.1117/12.2629490)
Improved polarization calibration of the BICEP3 CMB polarimeter at the South Pole
J Cornelison, C Vergès, PAR Ade, Z Ahmed, M Amiri, D Barkats, R Basu Thakur, D Beck, CA Bischoff, JJ Bock, V Buza, JR Cheshire, J Connors, M Crumrine, AJ Cukierman, EV Denison, MI Dierickx, L Duband, M Eiben, S Fatigoni, JP Filippini, C Giannakopoulos, N Goeckner-Wald, DC Goldfinger, J Grayson, PK Grimes, G Hall, G Halal, M Halpern, E Hand, SA Harrison, S Henderson, SR Hildebrandt, GC Hilton, J Hubmayr, H Hui, KD Irwin, J Kang, KS Karkare, S Kefeli, JM Kovac, CL Kuo, K Lau, EM Leitch, A Lennox, T Liu, K Look, KG Megerian, L Minutolo, L Moncelsi, Y Nakato, T Namikawa, HT Nguyen, R O'Brient, S Palladino, MA Petroff, T Prouve, C Pryke, B Racine, CD Reintsema, M Salatino, A Schillaci, BL Schmitt, B Singari, A Soliman, T St. Germaine, B Steinbach, RV Sudiwala, KL Thompson, C Tsai, C Tucker, AD Turner, C Umiltà, AG Vieregg, A Wandui, AC Weber, DV Wiebe, J Willmert, WLK Wu, H Yang, KW Yoon, E Young, C Yu, L Zeng, C Zhang, S Zhang
– Proceedings of SPIE--the International Society for Optical Engineering
(2022)
12190,
128
(doi: 10.1117/12.2620212)
Unified approach to secondary effects on the CMB B-mode polarization
T Namikawa, A Naruko, R Saito, A Taruya, D Yamauchi
– Journal of Cosmology and Astroparticle Physics
(2021)
2021,
029
(doi: 10.1088/1475-7516/2021/10/029)
Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season.
PAR Ade, Z Ahmed, M Amiri, D Barkats, RB Thakur, CA Bischoff, D Beck, JJ Bock, H Boenish, E Bullock, V Buza, JR Cheshire, J Connors, J Cornelison, M Crumrine, A Cukierman, EV Denison, M Dierickx, L Duband, M Eiben, S Fatigoni, JP Filippini, S Fliescher, N Goeckner-Wald, DC Goldfinger, J Grayson, P Grimes, G Hall, G Halal, M Halpern, E Hand, S Harrison, S Henderson, SR Hildebrandt, GC Hilton, J Hubmayr, H Hui, KD Irwin, J Kang, KS Karkare, E Karpel, S Kefeli, SA Kernasovskiy, JM Kovac, CL Kuo, K Lau, EM Leitch, A Lennox, KG Megerian, L Minutolo, L Moncelsi, Y Nakato, T Namikawa, HT Nguyen, R O'Brient, RW Ogburn, S Palladino, T Prouve, C Pryke, B Racine, CD Reintsema, S Richter, A Schillaci, R Schwarz, BL Schmitt, CD Sheehy, A Soliman, TS Germaine, B Steinbach, RV Sudiwala, GP Teply, KL Thompson, JE Tolan, C Tucker, AD Turner, C Umiltà, C Vergès, AG Vieregg, A Wandui, AC Weber, DV Wiebe, J Willmert, CL Wong, WLK Wu, H Yang, KW Yoon, E Young, C Yu, L Zeng, C Zhang, S Zhang, BICEP/<i>Keck</i> Collaboration
– Phys Rev Lett
(2021)
127,
151301
(doi: 10.1103/physrevlett.127.151301)
BICEP / Keck XV: The BICEP3 CMB Polarimeter and the First Three Year Data Set
BICEPK Collaboration, PAR Ade, Z Ahmed, M Amiri, D Barkats, RB Thakur, D Beck, C Bischoff, JJ Bock, H Boenish, E Bullock, V Buza, JRC IV, J Connors, J Cornelison, M Crumrine, A Cukierman, EV Denison, M Dierickx, L Duband, M Eiben, S Fatigoni, JP Filippini, S Fliescher, N Goeckner-Wald, DC Goldfinger, J Grayson, P Grimes, G Halal, G Hall, M Halpern, E Hand, S Harrison, S Henderson, SR Hildebrandt, GC Hilton, J Hubmayr, H Hui, KD Irwin, J Kang, KS Karkare, E Karpel, S Kefeli, SA Kernasovskiy, JM Kovac, CL Kuo, K Lau, EM Leitch, A Lennox, KG Megerian, L Minutolo, L Moncelsi, Y Nakato, T Namikawa, HT Nguyen, R O'Brient, RWO IV, S Palladino, T Prouve, C Pryke, B Racine, CD Reintsema, S Richter, A Schillaci, BL Schmitt, R Schwarz, CD Sheehy, A Soliman, TS Germaine, B Steinbach, RV Sudiwala, GP Teply, KL Thompson, JE Tolan, C Tucker, A Turner, C Umilta, C Verges, AG Vieregg, A Wandui, AC Weber, DV Wiebe, J Willmert, CL Wong, WLK Wu, H Yang, KW Yoon, E Young, C Yu, L Zeng, C Zhang, S Zhang
(2021)
(link to publication)
Constraining reionization with the first measurement of the cross-correlation between the CMB optical-depth fluctuations and the Compton y -map
T Namikawa, A Roy, BD Sherwin, N Battaglia, DN Spergel
– Physical Review D
(2021)
104,
063514
(doi: 10.1103/PhysRevD.104.063514)
Cosmic birefringence tomography and calibration-independence with reionization signals in the CMB
BD Sherwin, T Namikawa
(2021)
(link to publication)
Morphology of weak lensing convergence maps
D Munshi, T Namikawa, JD Mcewen, TD Kitching, FR Bouchet
– Monthly Notices of the Royal Astronomical Society
(2021)
507,
1421
(doi: 10.1093/mnras/stab2101)
The Atacama Cosmology Telescope: Summary of DR4 and DR5 Data Products and Data Access
M Mallaby-Kay, Z Atkins, S Aiola, S Amodeo, JE Austermann, JA Beall, DT Becker, JR Bond, E Calabrese, GE Chesmore, SK Choi, KT Crowley, O Darwish, EV Denison, MJ Devlin, SM Duff, AJ Duivenvoorden, J Dunkley, S Ferraro, K Fichman, PA Gallardo, JE Golec, Y Guan, D Han, M Hasselfield, JC Hill, GC Hilton, M Hilton, R Hložek, J Hubmayr, KM Huffenberger, JP Hughes, BJ Koopman, T Louis, A MacInnis, MS Madhavacheril, J McMahon, K Moodley, S Naess, T Namikawa, F Nati, LB Newburgh, JP Nibarger, MD Niemack, LA Page, M Salatino, E Schaan, A Schillaci, N Sehgal, BD Sherwin, C Sifón, S Simon, ST Staggs, ER Storer, JN Ullom, A Van Engelen, J Van Lanen, LR Vale, EJ Wollack, Z Xu
– The Astrophysical Journal Supplement Series
(2021)
255,
11
(doi: 10.3847/1538-4365/abfcc4)
The integrated angular bispectrum of weak lensing
G Jung, T Namikawa, M Liguori, D Munshi, A Heavens
– Journal of Cosmology and Astroparticle Physics
(2021)
2021,
055
(doi: 10.1088/1475-7516/2021/06/055)
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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