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

2025

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 Astronomical Journal. 992, 1, 18p., 158

Research output: Article

The La Silla Schmidt Southern Survey

Miller, A. A., Abrams, N. S., Aldering, G., Anand, S., Angus, C. R., Arcavi, I., Baltay, C., Bauer, F. E., Brethauer, D., Bloom, J. S., Bommireddy, H., Catelan, M., Chornock, R., Clark, P., Collett, T. E., Dimitriadis, G., Faris, S., Forster, F., Franckowiak, A., Galbany, L., Galleguillos, R. B., Goobar, A., Graur, O., Gutierrez, C. P., Hall, S., Hammerstein, E., Herner, K. R., Hook, I. M., Huston, M. J., Johansson, J., Kilpatrick, C. D., Kim, A. G., Knop, R. A., Kowalski, M. P., Kwok, L. A., LeBaron, N., Lin, K. W., Liu, C., Lu, J. R., Lu, W., Lunnan, R., Maguire, K., Makrygianni, L., Margutti, R., Maoz, D., Veres, P. M., Moore, T., Nayana, A. J., Nicholl, M., Nordin, J., Pignata, G., Polin, A., Poznanski, D., Prieto, J. L., Rabinowitz, D. L., Rehemtulla, N., Rigault, M., Ryczanowski, D., Sarin, N., Schulze, S., Shah, V. G., Sheng, X., Shilling, S. P. R., Simmons, B. D., Singh, A., Smith, G. P., Smith, M., Sollerman, J., Soumagnac, M. T., Stubbs, C. W., Sullivan, M., Suresh, A., Trakhtenbrot, B., Ward, C., Wiston, E., Xiong, H., Yao, Y., Nugent, P. E.

29 Sep 2025, In: Publications of the Astronomical Society of the Pacific. 137, 9, 30p., 094204

Research output: Article

Cosmography with the double-source-plane strong gravitational lens AGEL150745+052256

Sahu, N., Shajib, A. J., Tran, K. V., Skobe, H., Rhoades, S., Jones, T., Glazebrook, K., Collett, T. E., Suyu, S. H., Vasan G. C, K., Barone, T. M., Bowden, D. J., Ballard, D., Kacprzak, G. G., Sweet, S. M., Lewis, G. F., Nanayakkara, T.

20 Sep 2025, In: Astrophysical Journal. 991, 1, 17p., 72

Research output: Article

The revolution in strong lensing discoveries from Euclid

Lines, N. E., Li, T., Collett, T. E., Holloway, P., Nightingale, J. W., Rojas, K., Verma, A., Walmsley, M.

18 Aug 2025, In: Nature Astronomy. 9, 8, p. 1116-1122, 7p.

Research output: Article

Unveiling a 36 billion solar mass black hole at the centre of the Cosmic Horseshoe gravitational lens

Melo-Carneiro, C. R., Collett, T. E., Oldham, L. J., Enzi, W., Furlanetto, C., Chies-Santos, A. L., Li, T.

7 Aug 2025, In: Monthly Notices of the Royal Astronomical Society. 541, 4, p. 2853-2871, 19p.

Research output: Article

Euclid Quick Data Release (Q1). 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.

24 Jul 2025, In: Astronomy and Astrophysics

Research output: Article

Euclid Quick Data Release (Q1). 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.

17 Jun 2025, In: Astronomy and Astrophysics

Research output: Article

Euclid Quick Data Release (Q1). The Strong Lensing Discovery Engine D - Double-source-plane lens candidates

Collaboration, E., Li, T., Collett, T. E., Walmsley, M., Lines, N. E. P., Rojas, K., Nightingale, J. W., Enzi, W. J. R., Moustakas, L. A., Krawczyk, C., Gavazzi, R., Despali, G., Holloway, P., Schuldt, S., Courbin, F., Metcalf, R. B., Ballard, D. J., Verma, A., Clément, B., Degaudenzi, H., Melo, A., Barroso, J. A. A., Leuzzi, L., Manjón-García, A., Pearce-Casey, R., Sluse, D., Tortora, C., Massey, R., Mahler, G., More, A., Aghanim, N., Altieri, B., Amara, A., Andreon, S., Auricchio, N., Aussel, H., Baccigalupi, C., Baldi, M., Balestra, A., Bardelli, S., Battaglia, P., Bender, R., Bernardeau, F., Casas, S., Nichol, R. C., Percival, W. J., Schewtschenko, J. A., Gaztanaga, E., Nadathur, S., Naidoo, K.

13 Jun 2025, In: Astronomy and Astrophysics

Research output: Article

The overconcentrated dark halo in the strong lens SDSS J0946+1006 is a subhalo: evidence for self interacting dark matter?

Enzi, W. J. R., Krawczyk, C., Ballard, D., Collett, T.

1 Jun 2025, In: Monthly Notices of the Royal Astronomical Society. 540, 1, p. 247–263

Research output: Article

Euclid. I. Overview of the Euclid mission

Collaboration, E., Mellier, Y., Barroso, J. A. A., Achúcarro, A., Adamek, J., Adam, R., Addison, G. E., Aghanim, N., Aguena, M., Ajani, V., Akrami, Y., Al-Bahlawan, A., Alavi, A., Albuquerque, I. S., Alestas, G., Alguero, G., Allaoui, A., Allevato, V., Alonso-Tetilla, A. V., Altieri, B., Alvarez-Candal, A., Amara, A., Avila, S., Bacon, D., Beutler, F., Bose, B., Collett, T. E., Fiorini, B., Fonseca, J., Gaztanaga, E., Joudaki, S., Koyama, K., Leclercq, F., Manera, M., Maraston, C., Markovic, K., Nadathur, S., Nichol, R. C., Noller, J., Pace, F., Pattison, C., Percival, W. J., Pollack, J. E., Pourtsidou, A., Raccanelli, A., Schewtschenko, J. A., Whalen, D. J., Winther, H. -., Youles, S., Fonseca De La Bella, L.

1 May 2025, In: Astronomy and Astrophysics. 697, 94p., A1

Research output: Article

View all my research outputs

Professor Thomas Collett

Biography

Research outputs

2025