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Ian Harrison
(he/him)
Teams and roles for Ian Harrison
Research Fellow
Astronomy Instrumentation Group
Cardiff Hub for Astrophysics Research and Technology
Overview
I am currently a Research Fellow in cosmology in the School of Physics and Astronomy at Cardiff University.
I now have a few different research interests in observational and statistical cosmology, but my primary area of work is in developing cross-correlation methods between the Cosmic Microwave Background and other observables for the Simons Observatory.
I have worked on weak gravitational lensing, both in the radio with the SuperCLASS survey and the future SKAO Telescope, and in the optical with the Dark Energy Survey (DES). I am also interested in novel ways of combining radio and gravitational wave data to do cosmology, and in cosmology with galaxy cluster number counts.
Publication
2025
- Giardiello, S., Ade, P., Calabrese, E., Harrison, I., Jense, H. and Tucker, C. 2025. The Atacama Cosmology Telescope: DR6 maps. [Online]. ArXiv: Cornell university. (10.48550/arXiv.2503.14451) Available at: https://doi.org/10.48550/arXiv.2503.14451
- Giardiello, S., Calabrese, E., Jense, H., Ade, P., Harrison, I. and Tucker, C. 2025. The Atacama Cosmology Telescope: DR6 constraints on extended cosmological models. [Online]. ArXiv: Cornell university. (10.48550/arXiv.2503.14454) Available at: https://doi.org/10.48550/arXiv.2503.14454
- Bocquet, S. et al. 2025. Multiprobe cosmology from the abundance of SPT clusters and DES galaxy clustering and weak lensing. Physical Review D (particles, fields, gravitation, and cosmology) 111(6), article number: 63533. (10.1103/physrevd.111.063533)
- Gatti, M. et al. 2025. Dark Energy Survey Year 3 results: Simulation-based cosmological inference with wavelet harmonics, scattering transforms, and moments of weak lensing mass maps. II. cosmological results. Physical Review D (particles, fields, gravitation, and cosmology) 111(6), article number: 63504. (10.1103/physrevd.111.063504)
- Wenzl, L. et al. 2025. Atacama Cosmology Telescope: DR6 gravitational lensing and SDSS BOSS cross-correlation measurement and constraints on gravity with the EG statistic. Physical Review D (particles, fields, gravitation, and cosmology) 111(4), article number: 43535. (10.1103/physrevd.111.043535)
- Hale, C. L. et al. 2025. MIGHTEE: The continuum survey data release 1. Monthly Notices of the Royal Astronomical Society 536(3), pp. 2187-2211. (10.1093/mnras/stae2528)
- Jense, H., Harrison, I., Calabrese, E., Mancini, A. S., Bolliet, B., Dunkley, J. and Hill, J. 2025. A complete framework for cosmological emulation and inference with CosmoPower. RAS Techniques and Instruments 4, article number: rzaf002. (10.1093/rasti/rzaf002)
2024
- Faga, L. et al. 2024. Dark energy survey year 3 results: cosmology from galaxy clustering and galaxy–galaxy lensing in harmonic space. Monthly Notices of the Royal Astronomical Society 536(2), pp. 1586-1609. (10.1093/mnras/stae2654)
- Bocquet, S. et al. 2024. SPT clusters with DES and HST weak lensing. II. Cosmological constraints from the abundance of massive halos. Physical Review D (particles, fields, gravitation, and cosmology) 110(8), article number: 83510. (10.1103/physrevd.110.083510)
- Bocquet, S. et al. 2024. SPT clusters with DES and HST weak lensing. I. Cluster lensing and Bayesian population modeling of multiwavelength cluster datasets. Physical Review D (particles, fields, gravitation, and cosmology) 110(8), article number: 83509. (10.1103/physrevd.110.083509)
- Bigwood, L. et al. 2024. Weak lensing combined with the kinetic Sunyaev–Zel’dovich effect: a study of baryonic feedback. Monthly Notices of the Royal Astronomical Society 534(1), pp. 655-682. (10.1093/mnras/stae2100)
- Giardiello, S. et al. 2024. The Simons Observatory: impact of bandpass, polarization angle and calibration uncertainties on small-scale power spectrum analysis. Journal of Cosmology and Astroparticle Physics 2024, article number: 8. (10.1088/1475-7516/2024/09/008)
- Toribio San Cipriano, L. et al. 2024. Dark Energy Survey Deep Field photometric redshift performance and training incompleteness assessment. Astronomy & Astrophysics 686, article number: A38. (10.1051/0004-6361/202348956)
- Cordero, J. P. et al. 2024. AgriFoodPy: a package for modelling food systems. The Journal of Open Source Software 9(97), article number: 6305. (10.21105/joss.06305)
- Gatti, M. et al. 2024. Dark Energy Survey Year 3 results: Simulation-based cosmological inference with wavelet harmonics, scattering transforms, and moments of weak lensing mass maps. Validation on simulations. Physical Review D (particles, fields, gravitation, and cosmology) 109(6), article number: 63534. (10.1103/PhysRevD.109.063534)
- Madhavacheril, M. S. et al. 2024. The Atacama Cosmology Telescope: DR6 gravitational lensing map and cosmological parameters. Astrophysical Journal 962(2), article number: 113. (10.3847/1538-4357/acff5f)
- Qu, F. J. et al. 2024. The Atacama Cosmology Telescope: A measurement of the DR6 CMB lensing power spectrum and its implications for structure growth. Astrophysical Journal 962(2), article number: 112. (10.3847/1538-4357/acfe06)
- Marques, G. et al. 2024. Cosmological constraints from the tomography of DES-Y3 galaxies with CMB lensing from ACT DR4. Journal of Cosmology and Astroparticle Physics 2024(1), article number: 33. (10.1088/1475-7516/2024/01/033)
2023
- Anbajagane, D. et al. 2023. Beyond the 3rd moment: a practical study of using lensing convergence CDFs for cosmology with DES Y3. Monthly Notices of the Royal Astronomical Society 526(4), pp. 5530-5554. (10.1093/mnras/stad3118)
- Sánchez, C. et al. 2023. The Dark Energy Survey Year 3 high-redshift sample: Selection, characterization, and analysis of galaxy clustering. Monthly Notices of the Royal Astronomical Society 525(3), pp. 3896–3922. (10.1093/mnras/stad2402)
- Prat, J. et al. 2023. Non-local contribution from small scales in galaxy-galaxy lensing: Comparison of mitigation schemes. Monthly Notices of the Royal Astronomical Society 522(1), pp. 412-425. (10.1093/mnras/stad847)
- Lovell, C. C., Harrison, I., Harikane, Y., Tacchella, S. and Wilkins, S. M. 2023. Extreme value statistics of the halo and stellar mass distributions at high redshift: are JWST results in tension with ΛCDM?. Monthly Notices of the Royal Astronomical Society 518(2), pp. 2511–2520. (10.1093/mnras/stac3224)
- Abbott, T. et al. 2023. Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck . III. Combined cosmological constraints. Physical Review D 107, article number: 23531. (10.1103/PhysRevD.107.023531)
- Chang, C. et al. 2023. Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck . II. Cross-correlation measurements and cosmological constraints. Physical Review D 107(2), article number: 23530. (10.1103/PhysRevD.107.023530)
- Omori, Y. et al. 2023. Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck . I. Construction of CMB lensing maps and modeling choices. Physical Review D 107, article number: 23529. (10.1103/PhysRevD.107.023529)
2022
- Doux, C. et al. 2022. Dark energy survey year 3 results: cosmological constraints from the analysis of cosmic shear in harmonic space. Monthly Notices of the Royal Astronomical Society 515(2), pp. 1942-1972. (10.1093/mnras/stac1826)
- Secco, L. F. et al. 2022. Dark Energy Survey year 3 results: three-point shear correlations and mass aperture moments. Physical Review D 105(10), article number: 103537. (10.1103/PhysRevD.105.103537)
2013
- Harrison, I. 2013. Cosmology with extreme galaxy clusters. PhD Thesis, Cardiff University.
2012
- Harrison, I. and Coles, P. 2012. Testing cosmology with extreme galaxy clusters. Monthly Notices of the Royal Astronomical Society: Letters 421(1), pp. L19-L23. (10.1111/j.1745-3933.2011.01198.x)
2011
- Harrison, I. and Coles, P. 2011. Exact extreme value statistics and the halo mass function. Monthly Notices of the Royal Astronomical Society: Letters 418(1), pp. L20-L24. (10.1111/j.1745-3933.2011.01134.x)
Articles
- Bocquet, S. et al. 2025. Multiprobe cosmology from the abundance of SPT clusters and DES galaxy clustering and weak lensing. Physical Review D (particles, fields, gravitation, and cosmology) 111(6), article number: 63533. (10.1103/physrevd.111.063533)
- Gatti, M. et al. 2025. Dark Energy Survey Year 3 results: Simulation-based cosmological inference with wavelet harmonics, scattering transforms, and moments of weak lensing mass maps. II. cosmological results. Physical Review D (particles, fields, gravitation, and cosmology) 111(6), article number: 63504. (10.1103/physrevd.111.063504)
- Wenzl, L. et al. 2025. Atacama Cosmology Telescope: DR6 gravitational lensing and SDSS BOSS cross-correlation measurement and constraints on gravity with the EG statistic. Physical Review D (particles, fields, gravitation, and cosmology) 111(4), article number: 43535. (10.1103/physrevd.111.043535)
- Hale, C. L. et al. 2025. MIGHTEE: The continuum survey data release 1. Monthly Notices of the Royal Astronomical Society 536(3), pp. 2187-2211. (10.1093/mnras/stae2528)
- Jense, H., Harrison, I., Calabrese, E., Mancini, A. S., Bolliet, B., Dunkley, J. and Hill, J. 2025. A complete framework for cosmological emulation and inference with CosmoPower. RAS Techniques and Instruments 4, article number: rzaf002. (10.1093/rasti/rzaf002)
- Faga, L. et al. 2024. Dark energy survey year 3 results: cosmology from galaxy clustering and galaxy–galaxy lensing in harmonic space. Monthly Notices of the Royal Astronomical Society 536(2), pp. 1586-1609. (10.1093/mnras/stae2654)
- Bocquet, S. et al. 2024. SPT clusters with DES and HST weak lensing. II. Cosmological constraints from the abundance of massive halos. Physical Review D (particles, fields, gravitation, and cosmology) 110(8), article number: 83510. (10.1103/physrevd.110.083510)
- Bocquet, S. et al. 2024. SPT clusters with DES and HST weak lensing. I. Cluster lensing and Bayesian population modeling of multiwavelength cluster datasets. Physical Review D (particles, fields, gravitation, and cosmology) 110(8), article number: 83509. (10.1103/physrevd.110.083509)
- Bigwood, L. et al. 2024. Weak lensing combined with the kinetic Sunyaev–Zel’dovich effect: a study of baryonic feedback. Monthly Notices of the Royal Astronomical Society 534(1), pp. 655-682. (10.1093/mnras/stae2100)
- Giardiello, S. et al. 2024. The Simons Observatory: impact of bandpass, polarization angle and calibration uncertainties on small-scale power spectrum analysis. Journal of Cosmology and Astroparticle Physics 2024, article number: 8. (10.1088/1475-7516/2024/09/008)
- Toribio San Cipriano, L. et al. 2024. Dark Energy Survey Deep Field photometric redshift performance and training incompleteness assessment. Astronomy & Astrophysics 686, article number: A38. (10.1051/0004-6361/202348956)
- Cordero, J. P. et al. 2024. AgriFoodPy: a package for modelling food systems. The Journal of Open Source Software 9(97), article number: 6305. (10.21105/joss.06305)
- Gatti, M. et al. 2024. Dark Energy Survey Year 3 results: Simulation-based cosmological inference with wavelet harmonics, scattering transforms, and moments of weak lensing mass maps. Validation on simulations. Physical Review D (particles, fields, gravitation, and cosmology) 109(6), article number: 63534. (10.1103/PhysRevD.109.063534)
- Madhavacheril, M. S. et al. 2024. The Atacama Cosmology Telescope: DR6 gravitational lensing map and cosmological parameters. Astrophysical Journal 962(2), article number: 113. (10.3847/1538-4357/acff5f)
- Qu, F. J. et al. 2024. The Atacama Cosmology Telescope: A measurement of the DR6 CMB lensing power spectrum and its implications for structure growth. Astrophysical Journal 962(2), article number: 112. (10.3847/1538-4357/acfe06)
- Marques, G. et al. 2024. Cosmological constraints from the tomography of DES-Y3 galaxies with CMB lensing from ACT DR4. Journal of Cosmology and Astroparticle Physics 2024(1), article number: 33. (10.1088/1475-7516/2024/01/033)
- Anbajagane, D. et al. 2023. Beyond the 3rd moment: a practical study of using lensing convergence CDFs for cosmology with DES Y3. Monthly Notices of the Royal Astronomical Society 526(4), pp. 5530-5554. (10.1093/mnras/stad3118)
- Sánchez, C. et al. 2023. The Dark Energy Survey Year 3 high-redshift sample: Selection, characterization, and analysis of galaxy clustering. Monthly Notices of the Royal Astronomical Society 525(3), pp. 3896–3922. (10.1093/mnras/stad2402)
- Prat, J. et al. 2023. Non-local contribution from small scales in galaxy-galaxy lensing: Comparison of mitigation schemes. Monthly Notices of the Royal Astronomical Society 522(1), pp. 412-425. (10.1093/mnras/stad847)
- Lovell, C. C., Harrison, I., Harikane, Y., Tacchella, S. and Wilkins, S. M. 2023. Extreme value statistics of the halo and stellar mass distributions at high redshift: are JWST results in tension with ΛCDM?. Monthly Notices of the Royal Astronomical Society 518(2), pp. 2511–2520. (10.1093/mnras/stac3224)
- Abbott, T. et al. 2023. Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck . III. Combined cosmological constraints. Physical Review D 107, article number: 23531. (10.1103/PhysRevD.107.023531)
- Chang, C. et al. 2023. Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck . II. Cross-correlation measurements and cosmological constraints. Physical Review D 107(2), article number: 23530. (10.1103/PhysRevD.107.023530)
- Omori, Y. et al. 2023. Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck . I. Construction of CMB lensing maps and modeling choices. Physical Review D 107, article number: 23529. (10.1103/PhysRevD.107.023529)
- Doux, C. et al. 2022. Dark energy survey year 3 results: cosmological constraints from the analysis of cosmic shear in harmonic space. Monthly Notices of the Royal Astronomical Society 515(2), pp. 1942-1972. (10.1093/mnras/stac1826)
- Secco, L. F. et al. 2022. Dark Energy Survey year 3 results: three-point shear correlations and mass aperture moments. Physical Review D 105(10), article number: 103537. (10.1103/PhysRevD.105.103537)
- Harrison, I. and Coles, P. 2012. Testing cosmology with extreme galaxy clusters. Monthly Notices of the Royal Astronomical Society: Letters 421(1), pp. L19-L23. (10.1111/j.1745-3933.2011.01198.x)
- Harrison, I. and Coles, P. 2011. Exact extreme value statistics and the halo mass function. Monthly Notices of the Royal Astronomical Society: Letters 418(1), pp. L20-L24. (10.1111/j.1745-3933.2011.01134.x)
Thesis
- Harrison, I. 2013. Cosmology with extreme galaxy clusters. PhD Thesis, Cardiff University.
Websites
- Giardiello, S., Ade, P., Calabrese, E., Harrison, I., Jense, H. and Tucker, C. 2025. The Atacama Cosmology Telescope: DR6 maps. [Online]. ArXiv: Cornell university. (10.48550/arXiv.2503.14451) Available at: https://doi.org/10.48550/arXiv.2503.14451
- Giardiello, S., Calabrese, E., Jense, H., Ade, P., Harrison, I. and Tucker, C. 2025. The Atacama Cosmology Telescope: DR6 constraints on extended cosmological models. [Online]. ArXiv: Cornell university. (10.48550/arXiv.2503.14454) Available at: https://doi.org/10.48550/arXiv.2503.14454
Biography
I obtained an MSci from Imperial College London in Physics with Theoretical Physics in 2010 and a PhD in Astrophysics from Cardiff University in 2013. During my PhD I worked under the supervision of Prof Peter Coles on cosmology with extreme value statistics.
Since then I have been a Research Associate at the University of Manchester from 2013 to 2021 (and remain a visitor there). I was also a long-term visitor and then Postdoctoral Research Assistant at the University of Oxford from 2018 to 2021.
Contact Details
HarrisonI@cardiff.ac.uk
Queen's Buildings - North Building, Room N/3.20A, 5 The Parade, Newport Road, Cardiff, CF24 3AA
Queen's Buildings - North Building, Room N/3.20A, 5 The Parade, Newport Road, Cardiff, CF24 3AA
Research themes
Specialisms
- Cosmology and extragalactic astronomy