Philip Holloway

Research Fellow in Strong Gravitational Lensing (2025–present)
Institute of Cosmology and Gravitation, University of Portsmouth

Education

DPhil Astrophysics (2021–2026)
University of Oxford

MSci Astrophysics (First class, 2017–2021)
University of Cambridge

Selected Publications

• Lens Modeling and Cosmological Inference from an Impure Sample of Galaxy-Galaxy Strong Lenses
  Holloway, P., Verma, A., Marshall, P. J., et al. (2026, MNRAS accepted), arXiv:2609.21699

  This paper asks two questions. How well can we measure lens parameters in LSST data, and what can we do with the 90% of LSST lenses for which we won't have spectroscopic confirmation.
  Answers: 1) 3.7% precision in Einstein radius is achievable 2) Cosmology!

• Euclid Quick Data Release (Q1). Refining the strong lens sample with Space Warps crowd-sourced science
  Euclid Collaboration: Holloway, P., Verma, A., Collett, T. et al. (2026, A&A submitted), arxiv.org:2611.06667

  In this work we investigate the potential for citizen science to refine and grade samples of strong lens candidates. We find this method shows great promise, and will be crucial for large data releases such as Euclid DR1.

• Euclid Quick Data Release (Q1): The Strong Lensing Discovery Engine A – System overview and first lens sample
  Euclid Collaboration: Walmsley, M., Holloway, P., Lines, N. E. P., et al. (2026), A&A, 711, A26

  This paper presented 500 high-grade lenses identified in Euclid Q1 data, a 63 deg² region of sky. At the time, this was the largest catalogue of strong lenses identified from space-based data.

• Euclid Quick Data Release (Q1): The Strong Lensing Discovery Engine E – Ensemble classification of strong gravitational lenses: lessons for Data Release 1
  Euclid Collaboration: Holloway, P., Verma, A., Walmsley, M., et al. (2026), A&A, 711, A30

  Following the Q1 discoveries, this paper looks to the future, asking what lens purity is achievable when combining Euclid lens classifiers. We find an ensemble approach provides significant improvement.

• A Bayesian approach to strong lens finding in the era of wide-area surveys
  Holloway, P., Marshall, P. J., Verma, A., et al. (2024), MNRAS, 530, 1297

  Strong lens classifiers are numerous but often vary in performance. This paper presents a Bayesian formalism to combine multiple classifiers and produce calibrated probabilities that a system is a strong lens.

• On the detectability of strong lensing in near-infrared surveys
  Holloway, P., Verma, A., Marshall, P. J., More, A., Tecza, M. (2023), MNRAS

  This paper asks - are there any lenses detectable in JWST surveys? The answer is a resounding yes, which has been supported by recent spectacular discoveries (e.g. COWLS II).

• Strong gravitational lenses in the era of wide-field surveys
  Holloway, P. (2025), PhD thesis, University of Oxford

  My thesis studies a wide range of strong lens science from cosmological inference to lens finding.