Thomas Collett

Biography

I am an astrophysicist and cosmologist studying how dark energy is affecting the expansion of the Universe. I do this using a phenomenon called strong gravitational lensing, where the path of light from a background galaxy is bent by a massive foreground galaxy to produce multiple images of the background source. The location where the lensed images form is sensitive to the cosmological parameters and the dark matter distribution in the lens galaxy and throughout the Universe. I’m trying to probe all three with observations from the world's leading telescopes.

My research has been funded by the Royal Astronomical Society, University of Portsmouth, Science and Technolody Facilities Council and the Royal Society.

I won the Winton prize in 2020 and the Murdin prize in 2014.

I'm particularly proud of the following papers:

The most precise test of how mass warps spacetime over extragalactic scales

A large catalogue of new gravitational lenses discovered using machine learning

A cosmological model independent measurement of the Hubble constant

A measurement of the equation of state of dark energy from a double source plane lens

Research outputs

2026

Euclid Quick Data Release (Q1): XXVIII. The Strong Lensing Discovery Engine C - Finding lenses with machine learning

Collaboration, E., Lines, N. E. P., Collett, T. E., Walmsley, M., Rojas, K., Li, T., Leuzzi, L., Manjón-García, A., Vincken, S. H., Wilde, J., Holloway, P., Verma, A., Metcalf, R. B., Andika, I. T., Melo, A., Melchior, M., Sánchez, H. D., Díaz-Sánchez, A., Barroso, J. A. A., Clément, B., Krawczyk, C., Pearce-Casey, R., Serjeant, S., Courbin, F., Despali, G., Gavazzi, R., Schuldt, S., Degaudenzi, H., Ecker, L. R., Enzi, W. J. R., Finner, K., Galan, A., Giocoli, C., Hogg, N. B., Jahnke, K., Kruk, S., Mahler, G., More, A., Nagam, B. C., Pearson, J., de Murieta, A. S., Weisenbach, L., Amara, A., Casas, S., Nichol, R. C., Percival, W. J., Schewtschenko, J. A., Gaztanaga, E., Nadathur, S., Naidoo, K.

1 Jul 2026, In: Astronomy and Astrophysics. 711, 24p., A28

Research output: Article

Euclid Quick Data Release (Q1): XXVII. The strong-lensing discovery engine B. Early strong-lens candidates from the visual inspection of galaxies with a high-velocity dispersion

Collaboration, E., Rojas, K., Collett, T. E., Barroso, J. A. A., Nightingale, J. W., Stern, D., Moustakas, L. A., Schuldt, S., Despali, G., Melo, A., Walmsley, M., Ballard, D. J., Enzi, W. J. R., Li, T., de Murieta, A. S., Andika, I. T., Clément, B., Courbin, F., Ecker, L. R., Gavazzi, R., Jackson, N., Kovács, A., Matavulj, P., Meneghetti, M., Serjeant, S., Sluse, D., Tortora, C., Verma, A., Marchetti, L., O'Riordan, C. M., McCarthy, K., Suyu, S. H., Metcalf, R. B., Aghanim, N., Altieri, B., Amara, A., Andreon, S., Auricchio, N., Aussel, H., Baccigalupi, C., Baldi, M., Balestra, A., Bardelli, S., Casas, S., Nichol, R. C., Percival, W. J., Schewtschenko, J. A., Gaztanaga, E., Nadathur, S., Naidoo, K.

1 Jul 2026, In: Astronomy and Astrophysics. 711, 20p., A27

Research output: Article

Euclid Quick Data Release (Q1): XXVI. The Strong Lensing Discovery Engine A – System overview and first lens sample

Collaboration, E., Walmsley, M., Holloway, P., Lines, N. E. P., Rojas, K., Collett, T. E., Verma, A., Li, T., Nightingale, J. W., Despali, G., Schuldt, S., Gavazzi, R., Melo, A., Metcalf, R. B., Andika, I. T., Leuzzi, L., Manjón-García, A., Pearce-Casey, R., Vincken, S. H., Wilde, J., Busillo, V., Tortora, C., Barroso, J. A. A., Dole, H., Ecker, L. R., Pearson, J., Marshall, P. J., More, A., Saifollahi, T., Gracia-Carpio, J., Baeten, E., Cornen, C., Macmillan, C., Kruk, S., Remmelgas, K. A., Clément, B., Degaudenzi, H., Courbin, F., Bovy, J., Casas, S., Dannerbauer, H., Hogg, N. B., Weisenbach, L., Amara, A., Nichol, R. C., Percival, W. J., Schewtschenko, J. A., Gaztanaga, E., Nadathur, S., Naidoo, K.

1 Jul 2026, In: Astronomy and Astrophysics. 711, 21p., A26

Research output: Article

Euclid Quick Data Release (Q1): XXXII. From simulations to sky: Advancing machine-learning lens detection with real Euclid data

Collaboration, E., Lines, N. E. P., Collett, T. E., Holloway, P., Rojas, K., Schuldt, S., Metcalf, R. B., Li, T., Verma, A., Despali, G., Courbin, F., Gavazzi, R., Tortora, C., Clément, B., Aghanim, N., Altieri, B., Amendola, L., Andreon, S., Auricchio, N., Baccigalupi, C., Baldi, M., Balestra, A., Bardelli, S., Battaglia, P., Biviano, A., Branchini, E., Brescia, M., Camera, S., Cañas-Herrera, G., Capobianco, V., Carbone, C., Carretero, J., Castellano, M., Castignani, G., Cavuoti, S., Cimatti, A., Colodro-Conde, C., Congedo, G., Conselice, C. J., Conversi, L., Copin, Y., Courtois, H. M., Cropper, M., Degaudenzi, H., Percival, W. J., Schewtschenko, J. A., Beutler, F., Gaztanaga, E., Nadathur, S., Naidoo, K.

1 Jul 2026, In: Astronomy and Astrophysics. 711, 17p., A32

Research output: Article

Discovering Strong Gravitational Lenses in the Dark Energy Survey with Interactive Machine Learning and Crowd-sourced Inspection with Space Warps

González, J., Holloway, P., Collett, T., Verma, A., Bechtol, K., Marshall, P., More, A., Acevedo Barroso, J., Cartwright, G., Martinez, M., Li, T., Rojas, K., Schuldt, S., Birrer, S., Diehl, H. T., Morgan, R., Drlica-Wagner, A., O’Donnell, J. H., Zaborowski, E., Nord, B., Baeten, E. M., Johnson, L. C., Macmillan, C., Abbott, T. M., Aguena, M., Allam, S. S., Brooks, D., Buckley-Geer, E., Burke, D. L., Carnero Rosell, A., Carretero, J., Cawthon, R., Davis, T. M., De Vicente, J., Desai, S., Doel, P., Everett, S., Flaugher, B., Frieman, J., García-Bellido, J., Gaztanaga, E., Giannini, G., Gruen, D., Gruendl, R. A., Gutierrez, G., Hinton, S. R., Hollowood, D. L., Honscheid, K., James, D. J., Kuehn, K.

10 May 2026, In: Astrophysical Journal. 1002, 2, 26p., 116

Research output: Article

A Salpeter IMF and an NFW halo: Disentangling the dark and stellar mass of an elliptical galaxy through precise lens modelling of a double-source-plane system

Li, T., Collett, T. E., Krawczyk, C. M., Granata, G., Enzi, W. J. R., Ballard, D. J., Lines, N. E. P., de Murieta, A. S., Weisenbach, L., Ryczanowski, D.

1 May 2026, In: Monthly Notices of the Royal Astronomical Society. 548, 2, 18p., stag683

Research output: Article

iPTF16geu through the lens of thermonuclear explosion models

De Murieta, A. S., Magee, M. R., Li, T., Collett, T. E., Johansson, J.

1 Feb 2026, In: Monthly Notices of the Royal Astronomical Society. 546, 2, 16p., stag091

Research output: Article

The AGEL Survey Data Release 2: A gravitational lens sample for galaxy evolution and cosmology

Barone, T. M., Vasan, K. C., Tran, K. V., Kacprzak, G. G., Glazebrook, K., Jones, T., Bowden, D. J., Dalessandro, F., Sahu, N., Skobe, H., Allen, R. J., Baker, M. M., Ballard, D. J., Chen, Y., Collett, T. E., Ferrami, G., González, J., Gottemoller, W., Harshan, A., Huang, X., Iwamoto, L., Jacobs, C., Jeltema, T. E., Gupta, K. R., Lewis, G. F., Lopez, S., Nanayakkara, T., Nielsen, N. M., O’Donnell, J., Qu, H., Rhoades, S., Shajib, A. J., Sweet, S. M., Tejos, N.

2 Jan 2026, In: Astronomical Journal. 171, 1, 23p., 57

Research output: Article

2025

Lensed stars in galaxy-galaxy strong lensing - A JWST prediction for the Cosmic Horseshoe

Li, S. K., Weisenbach, L., Collett, T. E., Diego, J. M., Lim, J., Broadhurst, T. J., Chow, A., Enzi, W. J., Kelly, P. L., Melo-Carneiro, C. R., Palencia, J. M., Williams, L. L., Zhang, J.

5 Dec 2025, In: Monthly Notices of the Royal Astronomical Society. 544, 4, p. 4469-4481, 13p.

Research output: Article

TiDES: The 4MOST Time Domain Extragalactic Survey

Frohmaier, C., Vincenzi, M., Sullivan, M., Hönig, S. F., Smith, M., Addison, H., Collett, T., Dimitriadis, G., Ellis, R. S., Gandhi, P., Graur, O., Hook, I., Kelsey, L., Kim, Y. L., Lidman, C., Maguire, K., Makrygianni, L., Martin, B., Möller, A., Nichol, R. C., Nicholl, M., Schady, P., Simmons, B. D., Smartt, S. J., Tempel, E., Wiseman, P.

10 Oct 2025, In: The Astrophysical Journal. 992, 1, 18p., 158

Research output: Article

View all my research outputs

Professor Thomas Collett

Biography

Research outputs

2026

2025