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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

Position-dependent correlation function of weak-lensing convergence
D Munshi, G Jung, TD Kitching, J McEwen, M Liguori, T Namikawa, A Heavens
– Physical Review D
(2023)
107,
043516
(doi: 10.1103/physrevd.107.043516)
Impact of anisotropic birefringence on measuring cosmic microwave background lensing
H Cai, Y Guan, T Namikawa, A Kosowsky
– Physical Review D
(2023)
107,
043513
(doi: 10.1103/PhysRevD.107.043513)
Sensitivity Modeling for LiteBIRD
T Hasebe, PAR Ade, A Adler, E Allys, D Alonso, K Arnold, D Auguste, J Aumont, R Aurlien, J Austermann, S Azzoni, C Baccigalupi, AJ Banday, R Banerji, RB Barreiro, N Bartolo, S Basak, E Battistelli, L Bautista, J Beall, D Beck, S Beckman, K Benabed, J Bermejo-Ballesteros, M Bersanelli, J Bonis, J Borrill, F Bouchet, F Boulanger, S Bounissou, M Brilenkov, ML Brown, M Bucher, E Calabrese, M Calvo, P Campeti, A Carones, FJ Casas, A Catalano, A Challinor, V Chan, K Cheung, Y Chinone, J Cliche, F Columbro, W Coulton, J Cubas, A Cukierman, D Curtis, G D’Alessandro, K Dachlythra, P de Bernardis, T de Haan, E de la Hoz, M De Petris, SD Torre, C Dickinson, P Diego-Palazuelos, M Dobbs, T Dotani, D Douillet, L Duband, A Ducout, S Duff, JM Duval, K Ebisawa, T Elleflot, HK Eriksen, J Errard, T Essinger-Hileman, F Finelli, R Flauger, C Franceschet, U Fuskeland, S Galli, M Galloway, K Ganga, JR Gao, RT Genova-Santos, M Gerbino, M Gervasi, T Ghigna, S Giardiello, E Gjerløw, ML Gradziel, J Grain, L Grandsire, F Grupp, A Gruppuso, JE Gudmundsson, NW Halverson, J Hamilton, P Hargrave, M Hasegawa, M Hattori, M Hazumi, S Henrot-Versillé, LT Hergt, D Herman, D Herranz
– Journal of Low Temperature Physics
(2022)
211,
384
(doi: 10.1007/s10909-022-02921-7)
BICEP / Keck XVII: Line of Sight Distortion Analysis: Estimates of Gravitational Lensing, Anisotropic Cosmic Birefringence, Patchy Reionization, and Systematic Errors
BICEPK Collaboration, PAR Ade, Z Ahmed, M Amiri, D Barkats, RB Thakur, D Beck, CA 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, C Giannakopoulos, N Goeckner-Wald, DC Goldfinger, J Grayson, P Grimes, G Halal, G Hall, M Halpern, E Hand, S Harrison, S Henderson, SR Hildebrandt, 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, MA Petroff, T Prouve, C Pryke, B Racine, CD Reintsema, S Richter, A Schillaci, BL Schmitt, R Schwarz, CD Sheehy, B Singari, A Soliman, TS Germaine, B Steinbach, RV Sudiwala, GP Teply, KL Thompson, JE Tolan, C Tucker, AD 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
(2022)
(link to publication)
BICEP / Keck XVI: Characterizing Dust Polarization through Correlations with Neutral Hydrogen
BICEPK Collaboration, PAR Ade, Z Ahmed, M Amiri, D Barkats, RB Thakur, D Beck, CA Bischoff, JJ Bock, H Boenish, E Bullock, V Buza, JRC IV, SE Clark, J Connors, J Cornelison, M Crumrine, A Cukierman, EV Denison, M Dierickx, L Duband, M Eiben, S Fatigoni, JP Filippini, S Fliescher, C Giannakopoulos, N Goeckner-Wald, DC Goldfinger, J Grayson, P Grimes, G Halal, G Hall, M Halpern, E Hand, S Harrison, S Henderson, SR Hildebrandt, 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, MA Petroff, T Prouve, C Pryke, B Racine, CD Reintsema, S Richter, A Schillaci, BL Schmitt, R Schwarz, CD Sheehy, B Singari, A Soliman, TS Germaine, B Steinbach, RV Sudiwala, GP Teply, KL Thompson, JE Tolan, C Tucker, AD 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
(2022)
(link to publication)
Optical Characterization of OMT-Coupled TES Bolometers for LiteBIRD
J Hubmayr, PAR Ade, A Adler, E Allys, D Alonso, K Arnold, D Auguste, J Aumont, R Aurlien, JE Austermann, S Azzoni, C Baccigalupi, AJ Banday, R Banerji, RB Barreiro, N Bartolo, S Basak, E Battistelli, L Bautista, JA Beall, D Beck, S Beckman, K Benabed, J Bermejo-Ballesteros, M Bersanelli, J Bonis, J Borrill, F Bouchet, F Boulanger, S Bounissou, M Brilenkov, ML Brown, M Bucher, E Calabrese, M Calvo, P Campeti, A Carones, FJ Casas, A Catalano, A Challinor, V Chan, K Cheung, Y Chinone, C Chiocchetta, SE Clark, L Clermont, S Clesse, J Cliche, F Columbro, JA Connors, A Coppolecchia, W Coulton, J Cubas, A Cukierman, D Curtis, F Cuttaia, G D’Alessandro, K Dachlythra, P de Bernardis, T de Haan, E de la Hoz, M De Petris, S Della Torre, JJ Daz Garca, C Dickinson, P Diego-Palazuelos, M Dobbs, T Dotani, D Douillet, E Doumayrou, L Duband, A Ducout, SM Duff, JM Duval, K Ebisawa, T Elleflot, HK Eriksen, J Errard, T Essinger-Hileman, S Farrens, F Finelli, R Flauger, K Fleury-Frenette, C Franceschet, U Fuskeland, L Galli, S Galli, M Galloway, K Ganga, JR Gao, RT Genova-Santos, M Georges, M Gerbino, M Gervasi, T Ghigna, S Giardiello, E Gjerlw, RG Gonzles, ML Gradziel, J Grain
– Journal of Low Temperature Physics
(2022)
209,
396
(doi: 10.1007/s10909-022-02808-7)
Delensing the CMB with the cosmic infrared background: the impact of foregrounds
A Baleato Lizancos, A Challinor, BD Sherwin, T Namikawa
– Monthly Notices of the Royal Astronomical Society
(2022)
514,
5786
(doi: 10.1093/mnras/stac1705)
Is cosmic birefringence due to dark energy or dark matter? A tomographic approach
H Nakatsuka, T Namikawa, E Komatsu
– Physical Review D
(2022)
105,
123509
(doi: 10.1103/PhysRevD.105.123509)
Finding evidence for inflation and the origin of galactic magnetic fields with CMB surveys
S Mandal, N Sehgal, T Namikawa
– Physical Review D
(2022)
105,
063537
(doi: 10.1103/PhysRevD.105.063537)
BICEP/Keck XV: The BICEP3 Cosmic Microwave Background Polarimeter and the First Three-year Data Set
PAR Ade, Z Ahmed, M Amiri, D Barkats, RB Thakur, CA Bischoff, D Beck, JJ Bock, H Boenish, E Bullock, V Buza, JR Cheshire 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 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 Iv, 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
– The Astrophysical Journal
(2022)
927,
77
(doi: 10.3847/1538-4357/ac4886)
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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