Thomas Edward Collett Portrait

Professor Thomas Collett

Professor of Astrophysics

Thomas.Collett@port.ac.uk

PhD Supervisor

View my research outputs
Faculty of Technology Cosmology and astrophysics Institute of Cosmology and Gravitation

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

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

Stars as cosmic scales: measuring stellar mass with microlensed supernovae

Weisenbach, L., Collett, T., Enzi, W., Oldham, L., De Murieta, A. S.

1 May 2025, In: Monthly Notices of the Royal Astronomical Society. 539, 1, p. 393-404, 12p.

Research output: Article

Euclid: The Early Release Observations Lens Search Experiment

Acevedo Barroso, J. A., O’Riordan, C. M., Clément, B., Tortora, C., Collett, T. E., Courbin, F., Gavazzi, R., Metcalf, R. B., Busillo, V., Andika, I. T., Cabanac, R., Courtois, H. M., Crook-Mansour, J., Delchambre, L., Despali, G., Ecker, L. R., Franco, A., Holloway, P., Jackson, N., Jahnke, K., Mahler, G., Marchetti, L., Matavulj, P., Melo, A., Meneghetti, M., Moustakas, L. A., Müller, O., Nucita, A. A., Paulino-Afonso, A., Pearson, J., Rojas, K., Scarlata, C., Schuldt, S., Serjeant, S., Sluse, D., Suyu, S. H., Vaccari, M., Verma, A., Vernardos, G., Walmsley, M., Bouy, H., Walth, G. L., Powell, D. M., Bolzonella, M., Cuillandre, J. C., Kluge, M., Hogg, N. B., Amara, A., Casas, S., Nichol, R. C.

1 May 2025, In: Astronomy and Astrophysics. 697, 5, p. 1-16, 16p., A14

Research output: Article

Euclid: Searches for strong gravitational lenses using convolutional neural nets in Early Release Observations of the Perseus field

Pearce-Casey, R., Nagam, B. C., Wilde, J., Busillo, V., Ulivi, L., Andika, I. T., Manjón-García, A., Leuzzi, L., Matavulj, P., Serjeant, S., Walmsley, M., Barroso, J. A., O’Riordan, C. M., Clément, B., Tortora, C., Collett, T. E., Courbin, F., Gavazzi, R., Metcalf, R. B., Cabanac, R., Courtois, H. M., Crook-Mansour, J., Delchambre, L., Despali, G., Ecker, L. R., Franco, A., Holloway, P., Jahnke, K., Mahler, G., Marchetti, L., Melo, A., Meneghetti, M., Müller, O., Nucita, A. A., Pearson, J., Rojas, K., Scarlata, C., Schuldt, S., Sluse, D., Suyu, S. H., Vaccari, M., Vegetti, S., Verma, A., Vernardos, G., Bolzonella, M., Hogg, N. B., Amara, A., Casas, S., Markovic, K., Nichol, R. C.

25 Apr 2025, In: Astronomy and Astrophysics. 696, 4, p. 1-22, 22p., A214

Research output: Article

Correcting for selection biases in the determination of the hubble constant from time-delay cosmography

Li, T., Collett, T. E., Marshall, P. J., Erickson, S., Enzi, W., Oldham, L., Ballard, D.

1 Apr 2025, In: Monthly Notices of the Royal Astronomical Society. 538, 4, p. 2375-2391, 17p.

Research output: Article

Euclid: A complete Einstein ring in NGC 6505

O'Riordan, C. M., Oldham, L. J., Nersesian, A., Li, T., Collett, T. E., Sluse, D., Altieri, B., Clément, B., Vasan, K. G., Rhoades, S., Chen, Y., Jones, T., Adami, C., Gavazzi, R., Vegetti, S., Powell, D. M., Acevedo Barroso, J. A., Andika, I. T., Bhatawdekar, R., Cooray, A. R., Despali, G., Diego, J. M., Ecker, L. R., Galan, A., Gómez-Alvarez, P., Leuzzi, L., Meneghetti, M., Metcalf, R. B., Schirmer, M., Serjeant, S., Tortora, C., Vaccari, M., Vernardos, G., Walmsley, M., Amara, A., Andreon, S., Auricchio, N., Aussel, H., Baccigalupi, C., Baldi, M., Balestra, A., Bardelli, S., Basset, A., Battaglia, P., Bender, R., Bonino, D., Branchini, E., Casas, S., Markovic, K., Nichol, R. C.

10 Feb 2025, In: Astronomy and Astrophysics. 694, 13p., A145

Research output: Article

2024

Find the haystacks, then look for needles: the rate of strongly lensed supernovae in galaxy–galaxy strong gravitational lenses

de Murieta, A. S., Collett, T. E., Magee, M. R., Pierel, J. D. R., Enzi, W. J. R., Lokken, M., Gagliano, A., Ryczanowski, D.

1 Dec 2024, In: Monthly Notices of the Royal Astronomical Society. 535, 3, p. 2523-2537, 15p.

Research output: Article

How to break the mass sheet degeneracy with the light curves of microlensed Type Ia supernovae

Weisenbach, L., Collett, T., De Murieta, A. S., Krawczyk, C., Vernardos, G., Enzi, W., Lundgren, A.

1 Jul 2024, In: Monthly Notices of the Royal Astronomical Society. 531, 4, p. 4349-4362, 14p.

Research output: Article

Lensed Type Ia Supernova “Encore” at z = 2: the first instance of two multiply imaged supernovae in the same host galaxy

Pierel, J. D., Newman, A. B., Dhawan, S., Gu, M., Joshi, B. A., Li, T., Schuldt, S., Strolger, L. G., Suyu, S. H., Caminha, G. B., Cohen, S. H., Diego, J. M., DŚilva, J. C., Ertl, S., Frye, B. L., Granata, G., Grillo, C., Koekemoer, A. M., Li, J., Robotham, A., Summers, J., Treu, T., Windhorst, R. A., Zitrin, A., Agarwal, S., Agrawal, A., Arendse, N., Belli, S., Burns, C., Cañameras, R., Chakrabarti, S., Chen, W., Collett, T. E., Coulter, D. A., Ellis, R. S., Engesser, M., Foo, N., Fox, O. D., Gall, C., Garuda, N., Gezari, S., Gomez, S., Glazebrook, K., Hjorth, J., Huang, X., Jha, S. W., Kamieneski, P. S., Kelly, P., Larison, C., Moustakas, L. A., Pascale, M., Pérez-Fournon, I., Petrushevska, T., Poidevin, F., Rest, A., Shahbandeh, M., Shajib, A. J., Siebert, M., Storfer, C., Talbot, M., Wang, Q., Wevers, T., Zenati, Y.

1 Jun 2024, In: Astrophysical Journal Letters. 967, 2, 9p., L37

Research output: Article

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