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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. D101, 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. D95, 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. D96, 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 Communications93, 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

The Atacama Cosmology Telescope: DR6 Maps
S Naess, Y Guan, AJ Duivenvoorden, M Hasselfield, Y Wang, I Abril-Cabezas, GE Addison, PAR Ade, S Aiola, T Alford, D Alonso, M Amiri, R An, Z Atkins, JE Austermann, E Barbavara, N Battaglia, ES Battistelli, JA Beall, R Bean, A Beheshti, B Beringue, T Bhandarkar, E Biermann, B Bolliet, JR Bond, E Calabrese, V Capalbo, F Carrero, S Chen, G Chesmore, H-M Cho, SK Choi, SE Clark, RC Rosado, NF Cothard, K Coughlin, W Coulton, D Crichton, KT Crowley, MJ Devlin, S Dicker, CJ Duell, SM Duff, J Dunkley, R Dunner, CE Villagra, M Fankhanel, GS Farren, S Ferraro, A Foster, R Freundt, B Fuzia, PA Gallardo, X Garrido, S Giardiello, A Gill, J Givans, V Gluscevic, JE Golec, Y Gong, M Halpern, I Harrison, E Healy, S Henderson, B Hensley, C Hervías-Caimapo, JC Hill, GC Hilton, M Hilton, AD Hincks, R Hložek, S-PP Ho, J Hood, E Hornecker, ZB Huber, J Hubmayr, KM Huffenberger, JP Hughes, M Ikape, K Irwin, G Isopi, HT Jense, N Joshi, B Keller, J Kim, K Knowles, BJ Koopman, A Kosowsky, D Kramer, A Kusiak, AL Posta, A Laguë, V Lakey, E Lee, Y Li, Z Li, M Limon, M Lokken, T Louis, M Lungu, N MacCrann, A MacInnis, MS Madhavacheril, D Maldonado, F Maldonado, M Mallaby-Kay, GA Marques, JV Marrewijk, F McCarthy, J McMahon, Y Mehta, F Menanteau, K Moodley, TW Morris, T Mroczkowski, T Namikawa, F Nati, SK Nerval, L Newburgh, A Nicola, MD Niemack, MR Nolta, J Orlowski-Scherer, LA Page, S Pandey, B Partridge, KP Sarmiento, H Prince, R Puddu, FJ Qu, R Quiroga, DC Ragavan, BR Guachalla, KK Rogers, F Rojas, T Sakuma, E Schaan, BL Schmitt, N Sehgal, S Shaikh, BD Sherwin, C Sierra, J Sievers, C Sifón, S Simon, R Sonka, DN Spergel, ST Staggs, E Storer, K Surrao, ER Switzer, N Tampier, R Thornton, H Trac, C Tucker, J Ullom, LR Vale, AV Engelen, JV Lanen, C Vargas, EM Vavagiakis, K Wagoner, L Wenzl, EJ Wollack, K Zheng
(2025)
The Atacama Cosmology Telescope: DR6 Constraints on Extended Cosmological Models
E Calabrese, JC Hill, HT Jense, AL Posta, I Abril-Cabezas, GE Addison, PAR Ade, S Aiola, T Alford, D Alonso, M Amiri, R An, Z Atkins, JE Austermann, E Barbavara, N Barbieri, N Battaglia, ES Battistelli, JA Beall, R Bean, A Beheshti, B Beringue, T Bhandarkar, E Biermann, B Bolliet, JR Bond, V Capalbo, F Carrero, S Chen, G Chesmore, H-M Cho, SK Choi, SE Clark, NF Cothard, K Coughlin, W Coulton, D Crichton, KT Crowley, O Darwish, MJ Devlin, S Dicker, CJ Duell, SM Duff, AJ Duivenvoorden, J Dunkley, R Dunner, CE Villagra, M Fankhanel, GS Farren, S Ferraro, A Foster, R Freundt, B Fuzia, PA Gallardo, X Garrido, M Gerbino, S Giardiello, A Gill, J Givans, V Gluscevic, S Goldstein, JE Golec, Y Gong, Y Guan, M Halpern, I Harrison, M Hasselfield, A He, E Healy, S Henderson, B Hensley, C Hervías-Caimapo, GC Hilton, M Hilton, AD Hincks, R Hložek, S-PP Ho, J Hood, E Hornecker, ZB Huber, J Hubmayr, KM Huffenberger, JP Hughes, M Ikape, K Irwin, G Isopi, N Joshi, B Keller, J Kim, K Knowles, BJ Koopman, A Kosowsky, D Kramer, A Kusiak, A Lague, V Lakey, M Lattanzi, E Lee, Y Li, Z Li, M Limon, M Lokken, T Louis, M Lungu, N MacCrann, A MacInnis, MS Madhavacheril, D Maldonado, F Maldonado, M Mallaby-Kay, GA Marques, JV Marrewijk, F McCarthy, J McMahon, Y Mehta, F Menanteau, K Moodley, TW Morris, T Mroczkowski, S Naess, T Namikawa, F Nati, SK Nerval, L Newburgh, A Nicola, MD Niemack, MR Nolta, J Orlowski-Scherer, L Pagano, LA Page, S Pandey, B Partridge, KP Sarmiento, H Prince, R Puddu, FJ Qu, DC Ragavan, BR Guachalla, KK Rogers, F Rojas, T Sakuma, E Schaan, BL Schmitt, N Sehgal, S Shaikh, BD Sherwin, C Sierra, J Sievers, C Sifón, S Simon, R Sonka, DN Spergel, ST Staggs, E Storer, K Surrao, ER Switzer, N Tampier, L Thiele, R Thornton, H Trac, C Tucker, J Ullom, LR Vale, AV Engelen, JV Lanen, C Vargas, EM Vavagiakis, K Wagoner, Y Wang, L Wenzl, EJ Wollack, K Zheng
(2025)
The Atacama Cosmology Telescope: DR6 Power Spectra, Likelihoods and $Λ$CDM Parameters
T Louis, AL Posta, Z Atkins, HT Jense, I Abril-Cabezas, GE Addison, PAR Ade, S Aiola, T Alford, D Alonso, M Amiri, R An, JE Austermann, E Barbavara, N Battaglia, ES Battistelli, JA Beall, R Bean, A Beheshti, B Beringue, T Bhandarkar, E Biermann, B Bolliet, JR Bond, E Calabrese, V Capalbo, F Carrero, S Chen, G Chesmore, H-M Cho, SK Choi, SE Clark, NF Cothard, K Coughlin, W Coulton, D Crichton, KT Crowley, O Darwish, MJ Devlin, S Dicker, CJ Duell, SM Duff, AJ Duivenvoorden, J Dunkley, R Dunner, CE Villagra, M Fankhanel, GS Farren, S Ferraro, A Foster, R Freundt, B Fuzia, PA Gallardo, X Garrido, M Gerbino, S Giardiello, A Gill, J Givans, V Gluscevic, S Goldstein, JE Golec, Y Gong, Y Guan, M Halpern, I Harrison, M Hasselfield, E Healy, S Henderson, B Hensley, C Hervías-Caimapo, JC Hill, GC Hilton, M Hilton, AD Hincks, R Hložek, S-PP Ho, J Hood, E Hornecker, ZB Huber, J Hubmayr, KM Huffenberger, JP Hughes, M Ikape, K Irwin, G Isopi, N Joshi, B Keller, J Kim, K Knowles, BJ Koopman, A Kosowsky, D Kramer, A Kusiak, A Lague, V Lakey, E Lee, Y Li, Z Li, M Limon, M Lokken, M Lungu, N MacCrann, A MacInnis, MS Madhavacheril, D Maldonado, F Maldonado, M Mallaby-Kay, GA Marques, JV Marrewijk, F McCarthy, J McMahon, Y Mehta, F Menanteau, K Moodley, TW Morris, T Mroczkowski, S Naess, T Namikawa, F Nati, SK Nerval, L Newburgh, A Nicola, MD Niemack, MR Nolta, J Orlowski-Scherer, L Pagano, LA Page, S Pandey, B Partridge, KP Sarmiento, H Prince, R Puddu, FJ Qu, DC Ragavan, BR Guachalla, KK Rogers, F Rojas, T Sakuma, E Schaan, BL Schmitt, N Sehgal, S Shaikh, BD Sherwin, C Sierra, J Sievers, C Sifón, S Simon, R Sonka, DN Spergel, ST Staggs, E Storer, K Surrao, ER Switzer, N Tampier, R Thornton, H Trac, C Tucker, J Ullom, LR Vale, AV Engelen, JV Lanen, C Vargas, EM Vavagiakis, K Wagoner, Y Wang, L Wenzl, EJ Wollack, K Zheng
(2025)
Requirements on the gain calibration for LiteBIRD polarisation data with blind component separation
F Carralot, A Carones, N Krachmalnicoff, T Ghigna, A Novelli, L Pagano, F Piacentini, C Baccigalupi, D Adak, A Anand, J Aumont, S Azzoni, M Ballardini, AJ Banday, RB Barreiro, N Bartolo, S Basak, A Basyrov, M Bersanelli, M Bortolami, T Brinckmann, F Cacciotti, P Campeti, E Carinos, FJ Casas, K Cheung, L Clermont, F Columbro, G Conenna, G Coppi, A Coppolecchia, F Cuttaia, P de Bernardis, M De Lucia, S Della Torre, E Di Giorgi, P Diego-Palazuelos, T Essinger-Hileman, E Ferreira, F Finelli, C Franceschet, G Galloni, M Galloway, M Gervasi, RT Génova-Santos, S Giardiello, C Gimeno-Amo, E Gjerlow, A Gruppuso, M Hazumi, S Henrot-Versillé, LT Hergt, E Hivon, H Ishino, B Jost, K Kohri, L Lamagna, C Leloup, M Lembo, F Levrier, AI Lonappan, M López-Caniego, G Luzzi, J Macias-Perez, E Martinez-González, S Masi, S Matarrese, T Matsumura, S Micheli, M Monelli, L Montier, G Morgante, B Mot, L Mousset, Y Nagano, R Nagata, T Namikawa, P Natoli, I Obata, A Occhiuzzi, A Paiella, D Paoletti, G Pascual-Cisneros, G Patanchon, V Pavlidou, G Pisano, G Polenta, L Porcelli, G Puglisi, N Raffuzzi, M Remazeilles, JA Rubino-Martin, M Ruiz-Granda, J Sanghavi, D Scott, M Shiraishi, RM Sullivan, Y Takase, K Tassis, L Terenzi
– Journal of Cosmology and Astroparticle Physics
(2025)
2025,
019
Tomographic constraint on anisotropic cosmic birefringence
T Namikawa
– Physical Review D
(2025)
111,
023501
Multi-dimensional optimisation of the scanning strategy for the LiteBIRD space mission
Y Takase, L Vacher, H Ishino, G Patanchon, L Montier, SL Stever, K Ishizaka, Y Nagano, W Wang, J Aumont, K Aizawa, A Anand, C Baccigalupi, M Ballardini, AJ Banday, RB Barreiro, N Bartolo, S Basak, M Bersanelli, M Bortolami, T Brinckmann, E Calabrese, P Campeti, E Carinos, A Carones, FJ Casas, K Cheung, L Clermont, F Columbro, A Coppolecchia, F Cuttaia, G D'Alessandro, P de Bernardis, T de Haan, E de la Hoz, S Della Torre, P Diego-Palazuelos, HK Eriksen, J Errard, F Finelli, U Fuskeland, G Galloni, M Galloway, M Gervasi, T Ghigna, S Giardiello, C Gimeno-Amo, E Gjerløw, R González González, A Gruppuso, M Hazumi, S Henrot-Versillé, LT Hergt, K Ikuma, K Kohri, L Lamagna, M Lattanzi, C Leloup, M Lembo, F Levrier, AI Lonappan, M López-Caniego, G Luzzi, B Maffei, E Martínez-González, S Masi, S Matarrese, FT Matsuda, T Matsumura, S Micheli, M Migliaccio, M Monelli, G Morgante, B Mot, R Nagata, T Namikawa, A Novelli, K Odagiri, S Oguri, R Omae, L Pagano, D Paoletti, F Piacentini, M Pinchera, G Polenta, L Porcelli, N Raffuzzi, M Remazeilles, A Ritacco, M Ruiz-Granda, Y Sakurai, D Scott, Y Sekimoto, M Shiraishi, G Signorelli, RM Sullivan, H Takakura, L Terenzi, M Tomasi, M Tristram
– Journal of Cosmology and Astroparticle Physics
(2024)
2024,
036
LiteBIRD science goals and forecasts. Mapping the hot gas in the Universe
M Remazeilles, M Douspis, JA Rubiño-Martín, AJ Banday, J Chluba, P de Bernardis, M De Petris, C Hernández-Monteagudo, G Luzzi, J Macias-Perez, S Masi, T Namikawa, L Salvati, H Tanimura, K Aizawa, A Anand, J Aumont, C Baccigalupi, M Ballardini, RB Barreiro, N Bartolo, S Basak, M Bersanelli, D Blinov, M Bortolami, T Brinckmann, E Calabrese, P Campeti, E Carinos, A Carones, FJ Casas, K Cheung, L Clermont, F Columbro, A Coppolecchia, F Cuttaia, T de Haan, E de la Hoz, S Della Torre, P Diego-Palazuelos, G D'Alessandro, HK Eriksen, F Finelli, U Fuskeland, G Galloni, M Galloway, M Gervasi, RT Génova-Santos, T Ghigna, S Giardiello, C Gimeno-Amo, E Gjerløw, R González González, A Gruppuso, M Hazumi, S Henrot-Versillé, LT Hergt, D Herranz, K Kohri, E Komatsu, L Lamagna, M Lattanzi, C Leloup, F Levrier, AI Lonappan, M López-Caniego, B Maffei, E Martínez-González, S Matarrese, T Matsumura, S Micheli, M Migliaccio, M Monelli, L Montier, G Morgante, Y Nagano, R Nagata, A Novelli, R Omae, L Pagano, D Paoletti, V Pavlidou, F Piacentini, M Pinchera, G Polenta, L Porcelli, A Ritacco, M Ruiz-Granda, Y Sakurai, D Scott, M Shiraishi, SL Stever, RM Sullivan, Y Takase, K Tassis, L Terenzi, M Tomasi, M Tristram, L Vacher, B van Tent
– Journal of Cosmology and Astroparticle Physics
(2024)
2024,
026
Constraining ultralight ALP dark matter in light of cosmic birefringence
D Zhang, EGM Ferreira, I Obata, T Namikawa
– Physical Review D
(2024)
110,
103525
Efficient estimation of rotation-induced bias to reconstructed CMB lensing power spectrum
H Cai, Y Guan, T Namikawa, A Kosowsky
– Physical Review D
(2024)
110,
103507
Tomographic constraint on anisotropic cosmic birefringence
T Namikawa
(2024)
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Research Group

Relativity and Gravitation

Room

B1.09

Telephone

01223 337843