Skip to main content
Home
Department Of Physics text logo
  • Research
    • Our research
    • Our research groups
    • Our research in action
    • Research funding support
    • Summer internships for undergraduates
  • Study
    • Undergraduates
    • Postgraduates
  • Engage
    • For alumni
    • For business
    • For schools
    • For the public
Menu
Black Hole

Lensing of space time around a black hole. At Oxford we study black holes observationally and theoretically on all size and time scales - it is some of our core work.

Credit: ALAIN RIAZUELO, IAP/UPMC/CNRS. CLICK HERE TO VIEW MORE IMAGES.

Professor Pedro Ferreira

Professor of Astrophysics

Research theme

  • Particle astrophysics & cosmology

Sub department

  • Astrophysics

Research groups

  • Beecroft Institute for Particle Astrophysics and Cosmology
pedro.ferreira@physics.ox.ac.uk
Telephone: 01865 (2)73366
Denys Wilkinson Building, room 757
Personal Webpage
  • About
  • Publications

Assessing Cosmological Evidence for Nonminimal Coupling

Physical Review Letters American Physical Society (APS) 135:8 (2025) 081001

Authors:

William J Wolf, Carlos García-García, Theodore Anton, Pedro G Ferreira

Abstract:

The recent observational evidence of deviations from the Lambda cold dark matter model points toward the presence of evolving dark energy. The simplest possibility consists of a cosmological scalar field <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"> <mi>φ</mi> </math> , dubbed “quintessence,” driving the accelerated expansion. We assess the evidence for the existence of such a scalar field. We find that, if the accelerated expansion is driven by quintessence, the data favor a potential energy <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"> <mi>V</mi> <mo stretchy="false">(</mo> <mi>φ</mi> <mo stretchy="false">)</mo> </math> that is concave, i.e., <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"> <mrow> <msup> <mrow> <mi>m</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> <mo>=</mo> <msup> <mrow> <mi>d</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> <mi>V</mi> <mo>/</mo> <mi>d</mi> <msup> <mrow> <mi>φ</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> <mo>&lt;</mo> <mn>0</mn> </mrow> </math> . Furthermore, and more significantly, the data strongly favor a scalar field that is nonminimally coupled to gravity [Bayes factor <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"> <mrow> <mi>log</mi> <mo stretchy="false">(</mo> <mi>B</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mn>7.34</mn> <mo>±</mo> <mn>0.6</mn> </mrow> </math> ], leading to time variations in the gravitational constant on cosmological scales, and the existence of fifth forces on smaller scales. The fact that we do not observe such fifth forces implies that new physics must come into play on noncosmological scales that quintessence is an unlikely explanation for the observed cosmic acceleration.
More details from the publisher
More details

Euclid preparation

Astronomy & Astrophysics EDP Sciences 700 (2025) a78

Authors:

S de la Torre, F Marulli, E Keihänen, A Viitanen, M Viel, A Veropalumbo, E Branchini, D Tavagnacco, F Rizzo, J Valiviita, V Lindholm, V Allevato, G Parimbelli, E Sarpa, Z Ghaffari, A Amara, S Andreon, N Auricchio, C Baccigalupi, M Baldi, S Bardelli, A Basset, D Bonino, M Brescia, J Brinchmann, A Caillat, S Camera, V Capobianco, C Carbone, J Carretero, S Casas, FJ Castander, M Castellano, G Castignani, S Cavuoti, A Cimatti, C Colodro-Conde, G Congedo, CJ Conselice, L Conversi, Y Copin, F Courbin, HM Courtois, M Crocce, A Da Silva, H Degaudenzi, G De Lucia, AM Di Giorgio, J Dinis, F Dubath, CAJ Duncan, X Dupac, S Dusini, M Farina, S Farrens, F Faustini, S Ferriol, N Fourmanoit, M Frailis, E Franceschi, P Franzetti, M Fumana, S Galeotta, K George, W Gillard, B Gillis, C Giocoli, P Gómez-Alvarez, BR Granett, A Grazian, F Grupp, L Guzzo, SVH Haugan, W Holmes, F Hormuth, A Hornstrup, S Ilić, K Jahnke, M Jhabvala, B Joachimi, S Kermiche, A Kiessling, M Kilbinger, B Kubik, M Kunz, H Kurki-Suonio, S Ligori, PB Lilje, I Lloro, G Mainetti, D Maino, E Maiorano, O Mansutti, O Marggraf, K Markovic, M Martinelli, N Martinet, R Massey, S Maurogordato, E Medinaceli, S Mei, M Melchior, Y Mellier, M Meneghetti, E Merlin, G Meylan, M Moresco, B Morin, L Moscardini, E Munari, C Neissner, S-M Niemi, C Padilla, S Paltani, F Pasian, K Pedersen, WJ Percival, V Pettorino, S Pires, G Polenta, M Poncet, L Pozzetti, F Raison, A Renzi, J Rhodes, G Riccio, E Romelli, M Roncarelli, E Rossetti, R Saglia, Z Sakr, AG Sánchez, D Sapone, B Sartoris, P Schneider, T Schrabback, M Scodeggio, A Secroun, E Sefusatti, G Seidel, M Seiffert, S Serrano, C Sirignano, G Sirri, L Stanco, J Steinwagner, C Surace, P Tallada-Crespí, AN Taylor, I Tereno, R Toledo-Moreo, F Torradeflot, A Tsyganov, I Tutusaus, L Valenziano, T Vassallo, Y Wang, J Weller, A Zacchei, G Zamorani, E Zucca, A Biviano, M Bolzonella, E Bozzo, C Burigana, M Calabrese, D Di Ferdinando, JA Escartin Vigo, R Farinelli, F Finelli, L Gabarra, J Gracia-Carpio, S Matthew, N Mauri, A Mora, A Pezzotta, M Pöntinen, V Scottez, P Simon, A Spurio Mancini, M Tenti, M Wiesmann, Y Akrami, IT Andika, S Anselmi, M Archidiacono, F Atrio-Barandela, A Balaguera-Antolinez, D Bertacca, M Bethermin, A Blanchard, L Blot, H Böhringer, S Borgani, ML Brown, S Bruton, R Cabanac, A Calabro, B Camacho Quevedo, G Cañas-Herrera, A Cappi, F Caro, CS Carvalho, T Castro, KC Chambers, F Cogato, S Contarini, AR Cooray, O Cucciati, S Davini, F De Paolis, G Desprez, A Díaz-Sánchez, S Di Domizio, H Dole, S Escoffier, AG Ferrari, PG Ferreira, A Finoguenov, A Fontana, K Ganga, J García-Bellido, T Gasparetto, V Gautard, E Gaztanaga, F Giacomini, F Gianotti, G Gozaliasl, A Gregorio, M Guidi, CM Gutierrez, A Hall, S Hemmati, H Hildebrandt, J Hjorth, A Jimenez Muñoz, S Joudaki, JJE Kajava, Y Kang, V Kansal, D Karagiannis, CC Kirkpatrick, S Kruk, M Lattanzi, AMC Le Brun, S Lee, J Le Graet, L Legrand, M Lembo, J Lesgourgues, TI Liaudat, A Loureiro, J Macias-Perez, M Magliocchetti, F Mannucci, R Maoli, J Martín-Fleitas, CJAP Martins, L Maurin, RB Metcalf, M Miluzio, P Monaco, C Moretti, G Morgante, C Murray, S Nadathur, K Naidoo, A Navarro-Alsina, S Nesseris, K Paterson, L Patrizii, A Pisani, V Popa, D Potter, P Reimberg, I Risso, P-F Rocci, M Sahlén, A Schneider, M Schultheis, D Sciotti, E Sellentin, M Sereno, A Silvestri, LC Smith, K Tanidis, C Tao, N Tessore, G Testera, R Teyssier, S Toft, S Tosi, A Troja, M Tucci, C Valieri, D Vergani, G Verza, P Vielzeuf, NA Walton

Abstract:

The two-point correlation function of the galaxy spatial distribution is a major cosmological observable that enables constraints on the dynamics and geometry of the Universe. The Euclid mission is aimed at performing an extensive spectroscopic survey of approximately 20–30 million H α -emitting galaxies up to a redshift of about 2. This ambitious project seeks to elucidate the nature of dark energy by mapping the three-dimensional clustering of galaxies over a significant portion of the sky. This paper presents the methodology and software developed for estimating the three-dimensional two-point correlation function within the Euclid Science Ground Segment. The software is designed to overcome the significant challenges posed by the large and complex Euclid dataset, which involves millions of galaxies. The key challenges include efficient pair counting, managing computational resources, and ensuring the accuracy of the correlation function estimation. The software leverages advanced algorithms, including k -d tree, octree, and linked-list data partitioning strategies, to optimise the pair-counting process. These methods are crucial for handling the massive volume of data efficiently. The implementation also includes parallel processing capabilities using shared-memory open multi-processing to further enhance performance and reduce computation times. Extensive validation and performance testing of the software are presented. Those have been performed by using various mock galaxy catalogues to ensure that it meets the stringent accuracy requirement of the Euclid mission. The results indicate that the software is robust and can reliably estimate the two-point correlation function, which is essential for deriving cosmological parameters with high precision. Furthermore, the paper discusses the expected performance of the software during different stages of Euclid Wide Survey observations and forecasts how the precision of the correlation function measurements will improve over the mission’s timeline, highlighting the software’s capability to handle large datasets efficiently.
More details from the publisher

Euclid preparation

Astronomy & Astrophysics EDP Sciences 698 (2025) ARTN A233

Authors:

K Koyama, S Pamuk, S Casas, B Bose, P Carrilho, I Sáez-Casares, L Atayde, M Cataneo, B Fiorini, C Giocoli, Amc Le Brun, F Pace, A Pourtsidou, Y Rasera, Z Sakr, H-A Winther, E Altamura, J Adamek, M Baldi, M-A Breton, G Rácz, F Vernizzi, A Amara, S Andreon, N Auricchio, C Baccigalupi, S Bardelli, F Bernardeau, A Biviano, C Bodendorf, D Bonino, E Branchini, M Brescia, J Brinchmann, A Caillat, S Camera, G Cañas-Herrera, V Capobianco, C Carbone, J Carretero, M Castellano, G Castignani, S Cavuoti, Kc Chambers, A Cimatti, C Colodro-Conde, G Congedo, Cj Conselice, L Conversi, Y Copin

Abstract:

We study the constraint on f(R) gravity that can be obtained by photometric primary probes of the Euclid mission. Our focus is the dependence of the constraint on the theoretical modelling of the nonlinear matter power spectrum. In the Hu–Sawicki f(R) gravity model, we consider four different predictions for the ratio between the power spectrum in f(R) and that in Λ cold dark matter (ΛCDM): a fitting formula, the halo model reaction approach, ReACT, and two emulators based on dark matter only N-body simulations, FORGE and e-Mantis. These predictions are added to the MontePython implementation to predict the angular power spectra for weak lensing (WL), photometric galaxy clustering, and their cross-correlation. By running Markov chain Monte Carlo, we compare constraints on parameters and investigate the bias of the recovered f(R) parameter if the data are created by a different model. For the pessimistic setting of WL, one-dimensional bias for the f(R) parameter, log<inf>10</inf>| f<inf>R</inf><inf>0</inf>|, is found to be 0.5σ when FORGE is used to create the synthetic data with log<inf>10</inf>| f<inf>R</inf><inf>0</inf>| = −5.301 and fitted by e-Mantis. The impact of baryonic physics on WL is studied by using a baryonification emulator, BCemu. For the optimistic setting, the f(R) parameter and two main baryonic parameters are well constrained despite the degeneracies among these parameters. However, the difference in the nonlinear dark matter prediction can be compensated for the adjustment of baryonic parameters, and the one-dimensional marginalised constraint on log<inf>10</inf>| f<inf>R</inf><inf>0</inf>| is biased. This bias can be avoided in the pessimistic setting at the expense of weaker constraints. For the pessimistic setting, using the ΛCDM synthetic data for WL, we obtain the prior-independent upper limit of log<inf>10</inf>| f<inf>R</inf><inf>0</inf>| < −5.6. Finally, we implement a method to include theoretical errors to avoid the bias due to inaccuracies in the nonlinear matter power spectrum prediction.
More details from the publisher
More details

syren-baryon: Analytic emulators for the impact of baryons on the matter power spectrum

(2025)

Authors:

Lukas Kammerer, Deaglan J Bartlett, Gabriel Kronberger, Harry Desmond, Pedro G Ferreira
More details from the publisher

SYREN-NEW: Precise formulae for the linear and nonlinear matter power spectra with massive neutrinos and dynamical dark energy

Astronomy & Astrophysics EDP Sciences 698 (2025) a1

Authors:

Ce Sui, Deaglan J Bartlett, Shivam Pandey, Harry Desmond, Pedro G Ferreira, Benjamin D Wandelt
More details from the publisher
More details

Pagination

  • First page First
  • Previous page Prev
  • Page 1
  • Current page 2
  • Page 3
  • Page 4
  • Page 5
  • Page 6
  • Page 7
  • Page 8
  • Page 9
  • …
  • Next page Next
  • Last page Last

Footer Menu

  • Contact us
  • Giving to the Dept of Physics
  • Work with us
  • Media

User account menu

  • Log in

Follow us

FIND US

Clarendon Laboratory,

Parks Road,

Oxford,

OX1 3PU

CONTACT US

Tel: +44(0)1865272200

University of Oxfrod logo Department Of Physics text logo
IOP Juno Champion logo Athena Swan Silver Award logo

© University of Oxford - Department of Physics

Cookies | Privacy policy | Accessibility statement

Built by: Versantus

  • Home
  • Research
  • Study
  • Engage
  • Our people
  • News & Comment
  • Events
  • Our facilities & services
  • About us
  • Current students
  • Staff intranet