Kazuya Koyama

Biography

I am a Professor of Cosmology in the Institute of Cosmology and Gravitation at the University of Portsmouth. My research interests lie in theoretical cosmology, particularly the origin of structure in our Universe and the late time acceleration of the Universe. My research is supported by the Science and Technology Facilities Council. I was supported by the European Research Council’s consolidator grant “Cosmological Tests of Gravity” between 2015 and 2021 and the European Research Council’s starting grant, “Modified gravity models as an alternative to dark energy” between 2008 and 2013. I was awarded my PhD from Kyoto University in 2002. Previous awards include RCUK academic fellowship, PPARC psotdoctoral fellowship, Japanese JSPS potdoctoral fellowship. In 2009 I was awarded the Philipe Leverhulme prize and in 2010 I received the Young Scientist Award of the Physical Society of Japan. I recieved the Yukawa-Kimura prize of the Yukawa memorial foundation in 2023. I was a PI of a Royal Society International Joint Project with the Yukawa Institute at Kyoto University. The collaboration between Portsmouth and Kyoto University was awarded the Daiwa-Adrian prize in 2010.

Research interests

My main research interest lies in theoretical cosmology. I study the origin of structure in our Universe and test the early universe models using the statistical properties of the cosmic microwave background and the large scale structure of the Universe. I am also interested in explaining the late time acceleration of the Universe. Particularly I investigate a possibility to realise the late time acceleration by modifying general relativity on cosmological scales and develop cosmological tests of gravity.

Research outputs

2026

Biased tracers, Hybrid Effective Field Theory and Modified Gravity

Brando, G., Li, B., Koyama, K.

30 Sep 2026, In: Journal of Cosmology and Astroparticle Physics

Research output: Article

Disentangling modified gravity and galaxy bias with field-level inference

Hoyland, S., Saadeh, D., Koyama, K., Desmond, H.

28 Sep 2026, In: Monthly Notices of the Royal Astronomical Society

Research output: Article

Euclid preparation: CV. CosmoPostProcess: A simulation calibrated framework for weak lensing selection bias in richness-selected galaxy clusters

Collaboration, E., Ingrao, R., Borgani, S., Costanzi, M., Saro, A., Castro, T., Baumont, L., Aguena, M., Grandis, S., Murray, C., Bhargava, S., Munari, E., Altieri, B., Andreon, S., Auricchio, N., Baccigalupi, C., Baldi, M., Bardelli, S., Battaglia, P., Biviano, A., Branchini, E., Brescia, M., Camera, S., Capobianco, V., Carbone, C., Carretero, J., Castellano, M., Castignani, G., Cavuoti, S., Cimatti, A., Colodro-Conde, C., Congedo, G., Conversi, L., Copin, Y., Courbin, F., Courtois, H. M., Degaudenzi, H., Lucia, G. D., Dubath, F., Dupac, X., Escoffier, S., Farina, M., Farinelli, R., Beutler, F., Gaztanaga, E., Koyama, K., Nadathur, S., Naidoo, K., Pace, F., Pattison, C.

22 Sep 2026, In: Astronomy and Astrophysics. 713, 28p., A256

Research output: Article

Euclid preparation: CIII. Constraining parameterised models of modifications of gravity with the spectroscopic and photometric primary probes

Collaboration, E., Albuquerque, I. S., Frusciante, N., Sakr, Z., Srinivasan, S., Atayde, L., Bose, B., Cardone, V. F., Casas, S., Martinelli, M., Noller, J., Teixeira, E. M., Thomas, D. B., Tutusaus, I., Cataneo, M., Koyama, K., Lombriser, L., Pace, F., Silvestri, A., Aghanim, N., Amara, A., Andreon, S., Auricchio, N., Baccigalupi, C., Baldi, M., Bardelli, S., Biviano, A., Bonino, D., Branchini, E., Brescia, M., Brinchmann, J., Camera, S., Cañas-Herrera, G., Capobianco, V., Carbone, C., Carretero, J., Castellano, M., Castignani, G., Cavuoti, S., Chambers, K. C., Cimatti, A., Colodro-Conde, C., Congedo, G., Markovic, K., Nichol, R. C., Percival, W. J., Schewtschenko, J. A., Gaztanaga, E., Nadathur, S., Naidoo, K.

21 Sep 2026, In: Astronomy and Astrophysics. 713, 21p., A214

Research output: Article

Euclid preparation. Baryon acoustic oscillations extraction techniques: comparison and optimisation

Collaboration, E., Sarpa, E., Veropalumbo, A., Bonici, M., Kärcher, M., Crocce, M., Sefusatti, E., Maragliano, E., Branchini, E., Oliveri, C., Gambardella, G., Quevedo, B. C., Moretti, C., Monaco, P., Bautista, J., Viel, M., Percival, W. J., Nadathur, S., Pezzotta, A., Eggemeier, A., Bel, J., Carbone, C., Crespi, A., Radinović, S., Parimbelli, G., Farina, A., Risso, I., Guidi, M., Degni, G., Eisenstein, D., Beutler, F., García-García, C., Piccirilli, G., Sorce, J. G., Altieri, B., Andreon, S., Baccigalupi, C., Baldi, M., Bardelli, S., Battaglia, P., Biviano, A., Brescia, M., Camera, S., Gaztanaga, E., Koyama, K., Leclercq, F., Naidoo, K., Pace, F., Pattison, C., Pourtsidou, A.

6 Aug 2026, In: Astronomy and Astrophysics

Research output: Article

Euclid: VIII. Populating a dark universe with galaxies using SciPIC

Collaboration, E., Gonzalez, E. J., Carretero, J., Baghkhani, Z., Castander, F. J., Fosalba, P., Tallada-Crespí, P., Stadel, J., Potter, D., Tutusaus, I., Ramakrishnan, S., van Heukelum, M. L., Chisari, N. E., Marulli, F., Bolzonella, M., Pozzetti, L., Navarro-Gironés, D., Chaves-Montero, J., Parimbelli, G., Manera, M., Blot, L., Hoffmann, K., Huertas-Company, M., Monaco, P., Scarlata, C., Breton, M. -., Teyssier, R., Crocce, M., Congedo, G., Biviano, A., Hirschmann, M., Pezzotta, A., Hoekstra, H., Percival, W. J., Oesch, P. A., Bowler, R. A. A., Gonzalez-Perez, V., Avila, S., Kovács, A., Altieri, B., Andreon, S., Auricchio, N., Casas, S., Beutler, F., Gaztanaga, E., Koyama, K., Nadathur, S., Naidoo, K., Pace, F., Pattison, C.

6 Aug 2026, In: Astronomy and Astrophysics. 712, 24p., A90

Research output: Article

Dark sector interactions in the w → −1 limit: velocity locking in pure momentum exchange models

Cruickshank, N., Crittenden, R., Koyama, K., Bruni, M.

3 Jul 2026, In: Journal of Cosmology and Astroparticle Physics. 2026, 07, 18p., 019

Research output: Article

Euclid preparation. Review of forecast constraints on dark energy and modified gravity

Collaboration, E., Frusciante, N., Martinelli, M., Lombriser, L., Silvestri, A., Archidiacono, M., Baldi, M., Ballardini, M., Bartolo, N., Bellini, E., Benevento, G., Bertacca, D., Bonvin, C., Bose, B., Brax, P., Cardone, V. F., Casas, S., Elkhashab, M. Y., Ferreira, P. G., Finelli, F., Hassani, F., Ilić, S., Koyama, K., Kunz, M., Lepori, F., Lesgourgues, J., Martins, C. J. A. P., Mota, D. F., Noller, J., Pace, F., Paoletti, D., Parimbelli, G., Pettorino, V., Sakr, Z., Srinivasan, S., Teixeira, E. M., Tutusaus, I., Valageas, P., Winther, H. -., Adamek, J., Albuquerque, I. S., Atayde, L., Fiorini, B., Markovic, K., Nichol, R. C., Percival, W. J., Schewtschenko, J. A., Gaztanaga, E., Nadathur, S., Naidoo, K.

19 Jun 2026, In: Astronomy and Astrophysics

Research output: Article

Non-parametric exploration of minimally coupled gravity with phantom crossing

Cataneo, M., Koyama, K.

15 Jun 2026, In: Physical Review D. 113, 17p., 122006

Research output: Article

Dark energy constraints in light of theoretical priors

Shah, N., Koyama, K., Noller, J.

28 Jan 2026, In: Journal of Cosmology and Astroparticle Physics. 2026, 01, p. 1-49, 49p., 054

Research output: Article

View all my research outputs

Professor Kazuya Koyama

Biography

Research interests

Research outputs

2026