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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 science goals and forecasts: improving sensitivity to inflationary gravitational waves with multitracer delensing
T Namikawa, A Lonappan, C Baccigalupi, N Bartolo, D Beck, K Benabed, A Challinor, P Diego-Palazuelos, J Errard, S Farrens, A Gruppuso, N Krachmalnicoff, M Migliaccio, E Martínez-González, V Pettorino, G Piccirilli, M Ruiz-Granda, B Sherwin, J Starck, P Vielva, R Akizawa, A Anand, J Aumont, R Aurlien, S Azzoni, M Ballardini, A Banday, R Barreiro, M Bersanelli, D Blinov, M Bortolami, T Brinckmann, E Calabrese, P Campeti, A Carones, F Carralot, F Casas, K Cheung, L Clermont, F Columbro, G Conenna, A Coppolecchia, F Cuttaia, G D'Alessandro, P de Bernardis, T de Haan, M De Petris, S Della Torre, E Di Giorgi, H Eriksen, F Finelli, C Franceschet, U Fuskeland, G Galloni, M Galloway, M Georges, M Gerbino, M Gervasi, T Ghigna, S Giardiello, C Gimeno-Amo, E Gjerløw, M Hazumi, S Henrot-Versillé, L Hergt, E Hivon, K Kohri, E Komatsu, L Lamagna, M Lattanzi, C Leloup, M Lembo, M López-Caniego, G Luzzi, B Maffei, S Masi, M Massa, S Matarrese, T Matsumura, S Micheli, A Moggi, M Monelli, L Montier, G Morgante, B Mot, L Mousset, R Nagata, P Natoli, A Novelli, I Obata, A Occhiuzzi, L Pagano, A Paiella, D Paoletti, G Pascual-Cisneros, V Pavlidou, F Piacentini, M Pinchera, G Pisano, G Polenta
– Journal of Cosmology and Astroparticle Physics
(2024)
2024,
010
(doi: 10.1088/1475-7516/2024/06/010)
The Atacama Cosmology Telescope: Mitigating the Impact of Extragalactic Foregrounds for the DR6 Cosmic Microwave Background Lensing Analysis
N MacCrann, BD Sherwin, FJ Qu, T Namikawa, MS Madhavacheril, I Abril-Cabezas, R An, JE Austermann, N Battaglia, ES Battistelli, JA Beall, B Bolliet, JR Bond, H Cai, E Calabrese, WR Coulton, O Darwish, SM Duff, AJ Duivenvoorden, J Dunkley, GS Farren, S Ferraro, JE Golec, Y Guan, D Han, C Hervías-Caimapo, JC Hill, M Hilton, R Hložek, J Hubmayr, J Kim, Z Li, A Kosowsky, T Louis, J McMahon, G A. Marques, K Moodley, S Naess, MD Niemack, L Page, B Partridge, E Schaan, N Sehgal, C Sifón, EJ Wollack, M Salatino, JN Ullom, J Van Lanen, A Van Engelen, L Wenzl
– The Astrophysical Journal
(2024)
966,
138
(doi: 10.3847/1538-4357/ad2610)
Exact CMB B-mode power spectrum from anisotropic cosmic birefringence
T Namikawa
(2024)
(link to publication)
LiteBIRD Science Goals and Forecasts: Improving Sensitivity to Inflationary Gravitational Waves with Multitracer Delensing
T Namikawa, AI Lonappan, C Baccigalupi, N Bartolo, D Beck, K Benabed, A Challinor, P Diego-Palazuelos, J Errard, S Farrens, A Gruppuso, N Krachmalnicoff, M Migliaccio, E Martínez-González, V Pettorino, G Piccirilli, M Ruiz-Granda, B Sherwin, J Starck, P Vielva, R Akizawa, A Anand, J Aumont, R Aurlien, S Azzoni, M Ballardini, AJ Banday, RB Barreiro, M Bersanelli, D Blinov, M Bortolami, T Brinckmann, E Calabrese, P Campeti, A Carones, F Carralot, FJ Casas, K Cheung, L Clermont, F Columbro, G Conenna, A Coppolecchia, F Cuttaia, G D'Alessandro, PD Bernardis, TD Haan, MD Petris, SD Torre, ED Giorgi, HK Eriksen, F Finelli, C Franceschet, U Fuskeland, G Galloni, M Galloway, M Georges, M Gerbino, M Gervasi, T Ghigna, S Giardiello, C Gimeno-Amo, E Gjerløw, M Hazumi, S Henrot-Versillé, LT Hergt, E Hivon, K Kohri, E Komatsu, L Lamagna, M Lattanzi, C Leloup, M Lembo, M López-Caniego, G Luzzi, B Maffei, S Masi, M Massa, S Matarrese, T Matsumura, S Micheli, A Moggi, M Monelli, L Montier, G Morgante, B Mot, L Mousset, R Nagata, P Natoli, A Novelli, I Obata, A Occhiuzzi, L Pagano, A Paiella, D Paoletti, G Pascual-Cisneros, V Pavlidou, F Piacentini, M Pinchera, G Pisano, G Polenta, G Puglisi, M Remazeilles, A Ritacco, A Rizzieri, J Rubino-Martin, Y Sakurai, D Scott, M Shiraishi, G Signorelli, SL Stever, Y Takase, H Tanimura, A Tartari, K Tassis, L Terenzi, M Tristram, L Vacher, BV Tent, IK Wehus, G Weymann-Despres, M Zannoni, Y Zhou
(2023)
(link to publication)
BICEP Array: 150 GHz Detector Module Development
A Schillaci, PAR Ade, Z Ahmed, M Amiri, D Barkats, R Basu Thakur, CA Bischoff, D Beck, JJ Bock, V Buza, J Cheshire, J Connors, J Cornelison, M Crumrine, A Cukierman, E Denison, M Dierickx, L Duband, M Eiben, S Fatigoni, JP Filippini, C Giannakopoulos, N Goeckner-Wald, D Goldfinger, JA 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, S Kefeli, JM Kovac, CL Kuo, K Lau, EM Leitch, A Lennox, KG Megerian, OY Miller, L Minutolo, L Moncelsi, Y Nakato, T Namikawa, HT Nguyen, R O’Brient, S Palladino, M Petroff, N Precup, T Prouve, C Pryke, B Racine, CD Reintsema, BL Schmitt, B Singari, A Soliman, TS Germaine, B Steinbach, RV Sudiwala, KL Thompson, C Tucker, AD Turner, C Umiltà, C Verges, AG Vieregg, A Wandui, AC Weber, DV Wiebe, J Willmert, WLK Wu, E Yang, KW Yoon, E Young, C Yu, L Zeng, C Zhang, S Zhang
– Journal of Low Temperature Physics
(2023)
213,
317
(doi: 10.1007/s10909-023-03005-w)
Cosmic birefringence tomography with polarized Sunyaev-Zel'dovich effect
T Namikawa, I Obata
– Physical Review D
(2023)
108,
083510
(doi: 10.1103/PhysRevD.108.083510)
Gravitational lensing effect on cosmic birefringence
F Naokawa, T Namikawa
– Physical Review D
(2023)
108,
063525
(doi: 10.1103/physrevd.108.063525)
New Probe of Inflationary Gravitational Waves: Cross-Correlations of Lensed Primary CMB B-Modes with Large-Scale Structure
T Namikawa, BD Sherwin
– Phys Rev Lett
(2023)
131,
131001
(doi: 10.1103/PhysRevLett.131.131001)
Constraints on Early Dark Energy from Isotropic Cosmic Birefringence.
JR Eskilt, L Herold, E Komatsu, K Murai, T Namikawa, F Naokawa
– Phys Rev Lett
(2023)
131,
121001
(doi: 10.1103/PhysRevLett.131.121001)
Tensor-to-scalar ratio forecasts for extended LiteBIRD frequency configurations
U Fuskeland, J Aumont, R Aurlien, C Baccigalupi, AJ Banday, HK Eriksen, J Errard, RT Génova-Santos, T Hasebe, J Hubmayr, H Imada, N Krachmalnicoff, L Lamagna, G Pisano, D Poletti, M Remazeilles, KL Thompson, L Vacher, IK Wehus, S Azzoni, M Ballardini, RB Barreiro, N Bartolo, A Basyrov, D Beck, M Bersanelli, M Bortolami, M Brilenkov, E Calabrese, A Carones, FJ Casas, K Cheung, J Chluba, SE Clark, L Clermont, F Columbro, A Coppolecchia, G D'Alessandro, P De Bernardis, T De Haan, E De La Hoz, M De Petris, S Della Torre, P Diego-Palazuelos, F Finelli, C Franceschet, G Galloni, M Galloway, M Gerbino, M Gervasi, T Ghigna, S Giardiello, E Gjerløw, A Gruppuso, P Hargrave, M Hattori, M Hazumi, LT Hergt, D Herman, D Herranz, E Hivon, TD Hoang, K Kohri, M Lattanzi, AT Lee, C Leloup, F Levrier, AI Lonappan, G Luzzi, B Maffei, E Martínez-González, S Masi, S Matarrese, T Matsumura, M Migliaccio, L Montier, G Morgante, B Mot, L Mousset, R Nagata, T Namikawa, F Nati, P Natoli, S Nerval, A Novelli, L Pagano, A Paiella, D Paoletti, G Pascual-Cisneros, G Patanchon, V Pelgrims, F Piacentini, G Piccirilli, G Polenta, G Puglisi, N Raffuzzi, A Ritacco, JA Rubino-Martin, G Savini, D Scott
– Astronomy & Astrophysics
(2023)
676,
A42
(doi: 10.1051/0004-6361/202346155)
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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