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Faculty of Mathematics

 

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 mode coupling with isotropic polarization rotation
T Namikawa
– Monthly Notices of the Royal Astronomical Society
(2021)
506,
1250
(doi: 10.1093/mnras/stab1796)
Strong detection of the CMB lensing and galaxy weak lensing cross-correlation from ACT-DR4, Planck Legacy, and KiDS-1000
NC Robertson, D Alonso, J Harnois-Déraps, O Darwish, A Kannawadi, A Amon, M Asgari, M Bilicki, E Calabrese, SK Choi, MJ Devlin, J Dunkley, A Dvornik, T Erben, S Ferraro, MC Fortuna, B Giblin, D Han, C Heymans, H Hildebrandt, JC Hill, M Hilton, SPP Ho, H Hoekstra, J Hubmayr et al.
(2021)
(doi: 10.1051/0004-6361/202039975)
A numerical study of observational systematic errors in lensing analysis of CMB polarization
R Nagata, T Namikawa
– Progress of Theoretical and Experimental Physics
(2021)
2021,
ptab040
(doi: 10.1093/ptep/ptab040)
Position-Dependent Correlation Function of Weak Lensing Convergence
D Munshi, G Jung, TD Kitching, J McEwen, M Liguori, T Namikawa, A Heavens
(2021)
(link to publication)
BICEP/Keck XII: Constraints on axionlike polarization oscillations in the cosmic microwave background
PAR Ade, Z Ahmed, M Amiri, D Barkats, R Basu Thakur, CA Bischoff, JJ Bock, H Boenish, E Bullock, V Buza, JR Cheshire, J Connors, J Cornelison, M Crumrine, A Cukierman, M Dierickx, L Duband, S Fatigoni, JP Filippini, S Fliescher, N Goeckner-Wald, J Grayson, G Hall, M Halpern, S Harrison et al.
– Physical Review D
(2021)
103,
042002
(doi: 10.1103/physrevd.103.042002)
A demonstration of improved constraints on primordial gravitational waves with delensing
PAR Ade, Z Ahmed, M Amiri, AJ Anderson, JE Austermann, JS Avva, D Barkats, RB Thakur, JA Beall, AN Bender, BA Benson, F Bianchini, CA Bischoff, LE Bleem, JJ Bock, H Boenish, E Bullock, V Buza, JE Carlstrom, CL Chang, JR Cheshire, HC Chiang, TL Chou, R Citron, J Connors et al.
– Physical Review D
(2021)
103,
022004
(doi: 10.1103/physrevd.103.022004)
The Atacama Cosmology Telescope: delensed power spectra and parameters
D Han, N Sehgal, A MacInnis, A van Engelen, BD Sherwin, MS Madhavacheril, S Aiola, N Battaglia, JA Beall, DT Becker, E Calabrese, SK Choi, O Darwish, EV Denison, MJ Devlin, J Dunkley, S Ferraro, AE Fox, M Hasselfield, J Colin Hill, GC Hilton, M Hilton, R Hložek, J Hubmayr, JP Hughes et al.
– Journal of Cosmology and Astroparticle Physics
(2021)
2021,
031
(doi: 10.1088/1475-7516/2021/01/031)
The Atacama Cosmology Telescope: a measurement of the Cosmic Microwave Background power spectra at 98 and 150 GHz
SK Choi, M Hasselfield, S-PP Ho, B Koopman, M Lungu, MH Abitbol, GE Addison, PAR Ade, S Aiola, D Alonso, M Amiri, S Amodeo, E Angile, JE Austermann, T Baildon, N Battaglia, JA Beall, R Bean, DT Becker, JR Bond, SM Bruno, E Calabrese, V Calafut, LE Campusano, F Carrero et al.
– Journal of Cosmology and Astroparticle Physics
(2020)
2020,
045
(doi: 10.1088/1475-7516/2020/12/045)
The Atacama Cosmology Telescope: DR4 maps and cosmological parameters
S Aiola, E Calabrese, L Maurin, S Naess, BL Schmitt, MH Abitbol, GE Addison, PAR Ade, D Alonso, M Amiri, S Amodeo, E Angile, JE Austermann, T Baildon, N Battaglia, JA Beall, R Bean, DT Becker, J Richard Bond, SM Bruno, V Calafut, LE Campusano, F Carrero, GE Chesmore, HM Cho et al.
– Journal of Cosmology and Astroparticle Physics
(2020)
2020,
047
(doi: 10.1088/1475-7516/2020/12/047)
The Atacama Cosmology Telescope: A CMB lensing mass map over 2100 square degrees of sky and its cross-correlation with BOSS-CMASS galaxies
O Darwish, MS Madhavacheril, BD Sherwin, S Aiola, N Battaglia, JA Beall, DT Becker, JR Bond, E Calabrese, SK Choi, MJ Devlin, J Dunkley, R Dünner, S Ferraro, AE Fox, PA Gallardo, Y Guan, M Halpern, D Han, M Hasselfield, JC Hill, GC Hilton, M Hilton, AD Hincks, SP Patty Ho et al.
– Monthly Notices of the Royal Astronomical Society
(2020)
500,
2250
(doi: 10.1093/mnras/staa3438)
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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