Martin Sahlén
Researcher at Department of Physics and Astronomy; Astronomy and Space Physics
- Telephone:
- +46 18 471 59 70
- E-mail:
- martin.sahlen@physics.uu.se
- Visiting address:
- Ångströmlaboratoriet, Regementsvägen 10
752 37 Uppsala - Postal address:
- Box 524
751 20 UPPSALA
- ORCID:
- 0000-0003-0973-4804
Short presentation
Docent in astronomy with specialization in astrophysics.
RESEARCH
2021-2026: PI, "The Galaxy – Dark Matter Connection with HST, JWST and EUCLID" (8 MSEK)
2022-2024: PI, "Searching for New Physics in the Early Universe" (1 MSEK)
2023-2027: PI, "Astronomical object classification and anomaly detection with complex spectroscopic 4MOST data sets" (4 MSEK)
TEACHING
Responsible for and teacher on the transdisciplinary course "Three Views on Cosmology" (10 hp).
Keywords
- docent
- bayesian inference
- astrophysics
- astronomy
- cosmology
Biography
Hemsida: http://www.astro.uu.se/~msahlen/
Martin Sahlén is docent and researcher in astronomy with specialization in astrophysics at Uppsala University. He studied at the Royal Institute of Technology (KTH) and Cambridge, earned his PhD from the University of Sussex in 2009, and was a postdoctoral fellow at Cambridge, Stockholm and Oxford. He was a Fulbright fellow at Johns Hopkins, and a Natural Sciences fellow at the Swedish Collegium for Advanced Study. He joined Uppsala University in 2016.
Sahlén's research focuses on the large-scale structure of the Universe, and its connection to astrophysics and fundamental physics. In particular, he is investigating the very first generations of galaxies, and late-Universe galaxy distributions. Recent work includes the demonstration of the power of galaxy clusters and cosmic voids as probes of deviations from General Relativity and to measure the mass of neutrinos, the first cosmological parameter estimation based on cosmic voids, and discovery of a powerful new test of modified gravity theories. He is member of the 4-metre Multi-Object Spectroscopic Telescope (4MOST), the BUFFALO survey, the Euclid Consortium, the SKA Observatory, and an external collaborator in the Dark Energy Survey. Sahlén also works on the philosophy of astrophysics and cosmology. His research was highlighted in “The Best Writing on Mathematics 2018”.
Research
Theoretical and observational studies of the large-scale structure of the Universe through clusters of galaxies, voids, and the first galaxies in the Universe - to understand galaxy astrophysics/star formation, dark energy, dark matter, cosmic inflation, and the reionization process in the early Universe.
Participant in the scientific projects 4MOST, BUFFALO, Euclid, and SKA Observatory. External Collaborator in the Dark Energy Survey. Also participating in the scientific exploitation of data from the Hubble Space Telescope and the coming James Webb Space Telescope.
Theoretical studies of the philosophy of cosmology, such as model inference, fine-tuning of the constants of nature, and multiverse explanations.

Publications
Recent publications
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Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation: LXXXVIII. 3D reconstruction of the cosmic web with Euclid Deep spectroscopic samples
- Download full text (pdf) of Euclid preparation: LXXXVIII. 3D reconstruction of the cosmic web with Euclid Deep spectroscopic samples
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Euclid preparation: LXXXIX. Accurate and precise data-driven angular power spectrum covariances
Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation: LXXXIX. Accurate and precise data-driven angular power spectrum covariances
- Download full text (pdf) of Euclid preparation: LXXXIX. Accurate and precise data-driven angular power spectrum covariances
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Euclid: VII. Structural-thermal-optical performance
Part of Astronomy and Astrophysics, 2026
- DOI for Euclid: VII. Structural-thermal-optical performance
- Download full text (pdf) of Euclid: VII. Structural-thermal-optical performance
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Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation LXXXVII. Non-Gaussianity of two-point statistics likelihood: Precise analysis of the matter power spectrum distribution
- Download full text (pdf) of Euclid preparation LXXXVII. Non-Gaussianity of two-point statistics likelihood: Precise analysis of the matter power spectrum distribution
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Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation LXXXVI. Cosmic Dawn Survey: Evolution of the galaxy stellar mass function across 0.2 < z ≤ 6.5 measured over 10 square degrees
- Download full text (pdf) of Euclid preparation LXXXVI. Cosmic Dawn Survey: Evolution of the galaxy stellar mass function across 0.2 < z ≤ 6.5 measured over 10 square degrees
All publications
Articles in journal
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Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation: LXXXVIII. 3D reconstruction of the cosmic web with Euclid Deep spectroscopic samples
- Download full text (pdf) of Euclid preparation: LXXXVIII. 3D reconstruction of the cosmic web with Euclid Deep spectroscopic samples
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Euclid preparation: LXXXIX. Accurate and precise data-driven angular power spectrum covariances
Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation: LXXXIX. Accurate and precise data-driven angular power spectrum covariances
- Download full text (pdf) of Euclid preparation: LXXXIX. Accurate and precise data-driven angular power spectrum covariances
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Euclid: VII. Structural-thermal-optical performance
Part of Astronomy and Astrophysics, 2026
- DOI for Euclid: VII. Structural-thermal-optical performance
- Download full text (pdf) of Euclid: VII. Structural-thermal-optical performance
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Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation LXXXVII. Non-Gaussianity of two-point statistics likelihood: Precise analysis of the matter power spectrum distribution
- Download full text (pdf) of Euclid preparation LXXXVII. Non-Gaussianity of two-point statistics likelihood: Precise analysis of the matter power spectrum distribution
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Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation LXXXVI. Cosmic Dawn Survey: Evolution of the galaxy stellar mass function across 0.2 < z ≤ 6.5 measured over 10 square degrees
- Download full text (pdf) of Euclid preparation LXXXVI. Cosmic Dawn Survey: Evolution of the galaxy stellar mass function across 0.2 < z ≤ 6.5 measured over 10 square degrees
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Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation: LXXVIII. Full-shape modelling of two-point and three-point correlation functions in real space
- Download full text (pdf) of Euclid preparation: LXXVIII. Full-shape modelling of two-point and three-point correlation functions in real space
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Euclid preparation XXVII. The NISP spectroscopy channel: Ground performance and calibration
Part of Astronomy and Astrophysics, 2026
- DOI for Euclid preparation XXVII. The NISP spectroscopy channel: Ground performance and calibration
- Download full text (pdf) of Euclid preparation XXVII. The NISP spectroscopy channel: Ground performance and calibration
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Euclid preparation: LXXVI. Simulating thousands of Euclid spectroscopic skies
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXXVI. Simulating thousands of Euclid spectroscopic skies
- Download full text (pdf) of Euclid preparation: LXXVI. Simulating thousands of Euclid spectroscopic skies
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Part of Astronomy and Astrophysics, 2025
- DOI for LXXIII. Spatially resolved stellar populations of local galaxies with Euclid: A proof of concept using synthetic images with the TNG50 simulation
- Download full text (pdf) of LXXIII. Spatially resolved stellar populations of local galaxies with Euclid: A proof of concept using synthetic images with the TNG50 simulation
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation LXXV. Estimating galaxy physical properties using CatBoost chained regressors with attention
- Download full text (pdf) of Euclid preparation LXXV. Estimating galaxy physical properties using CatBoost chained regressors with attention
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXXIV. Euclidised observations of Hubble Frontier Fields and CLASH galaxy clusters
- Download full text (pdf) of Euclid preparation: LXXIV. Euclidised observations of Hubble Frontier Fields and CLASH galaxy clusters
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Part of Journal of Cosmology and Astroparticle Physics, 2025
- DOI for The re-markable 21-cm power spectrum. Part I. Probing the HI distribution in the post-reionization era using marked statistics
- Download full text (pdf) of The re-markable 21-cm power spectrum. Part I. Probing the HI distribution in the post-reionization era using marked statistics
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXXII. Three-dimensional galaxy clustering in configuration space: Two-point correlation function estimation
- Download full text (pdf) of Euclid preparation: LXXII. Three-dimensional galaxy clustering in configuration space: Two-point correlation function estimation
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXVI. Impact of line-of-sight projections on the covariance between galaxy cluster multi-wavelength observable properties
- Download full text (pdf) of Euclid preparation: LXVI. Impact of line-of-sight projections on the covariance between galaxy cluster multi-wavelength observable properties
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXXI. Simulations and nonlinearities beyond ÎCDM. 3. Constraints on f(R) models from the photometric primary probes
- Download full text (pdf) of Euclid preparation: LXXI. Simulations and nonlinearities beyond ÎCDM. 3. Constraints on f(R) models from the photometric primary probes
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Euclid: IV. The NISP Calibration Unit
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid: IV. The NISP Calibration Unit
- Download full text (pdf) of Euclid: IV. The NISP Calibration Unit
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Euclid preparation: LXIV. The Cosmic Dawn Survey (DAWN) of the Euclid Deep and Auxiliary Fields
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXIV. The Cosmic Dawn Survey (DAWN) of the Euclid Deep and Auxiliary Fields
- Download full text (pdf) of Euclid preparation: LXIV. The Cosmic Dawn Survey (DAWN) of the Euclid Deep and Auxiliary Fields
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Euclid: V. The Flagship galaxy mock catalogue: A comprehensive simulation for the Euclid mission
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid: V. The Flagship galaxy mock catalogue: A comprehensive simulation for the Euclid mission
- Download full text (pdf) of Euclid: V. The Flagship galaxy mock catalogue: A comprehensive simulation for the Euclid mission
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Euclid I. Overview of the Euclid mission
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid I. Overview of the Euclid mission
- Download full text (pdf) of Euclid I. Overview of the Euclid mission
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXIII. Simulations and non-linearities beyond Lambda cold dark matter. 2. Results from non-standard simulations
- Download full text (pdf) of Euclid preparation: LXIII. Simulations and non-linearities beyond Lambda cold dark matter. 2. Results from non-standard simulations
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXV. Determining the weak lensing mass accuracy and precision for galaxy clusters
- Download full text (pdf) of Euclid preparation: LXV. Determining the weak lensing mass accuracy and precision for galaxy clusters
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Euclid preparation: LXVIII. Extracting physical parameters from galaxies with machine learning
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXVIII. Extracting physical parameters from galaxies with machine learning
- Download full text (pdf) of Euclid preparation: LXVIII. Extracting physical parameters from galaxies with machine learning
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXX. Forecasting detection limits for intracluster light in the Euclid Wide Survey
- Download full text (pdf) of Euclid preparation: LXX. Forecasting detection limits for intracluster light in the Euclid Wide Survey
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation LXIX. The impact of relativistic redshift-space distortions on two-point clustering statistics from the Euclid wide spectroscopic survey
- Download full text (pdf) of Euclid preparation LXIX. The impact of relativistic redshift-space distortions on two-point clustering statistics from the Euclid wide spectroscopic survey
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Euclid: III. The NISP Instrument
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid: III. The NISP Instrument
- Download full text (pdf) of Euclid: III. The NISP Instrument
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Euclid: II. The VIS instrument
Part of Astronomy and Astrophysics, 2025
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LVII. Observational expectations for redshift z<7 active galactic nuclei in the Euclid Wide and Deep surveys
- Download full text (pdf) of Euclid preparation: LVII. Observational expectations for redshift z<7 active galactic nuclei in the Euclid Wide and Deep surveys
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation LXI. Cosmic Dawn Survey: 'Pre-launch' multiwavelength catalogues for Euclid Deep Field North and Euclid Deep Field Fornax
- Download full text (pdf) of Euclid preparation LXI. Cosmic Dawn Survey: 'Pre-launch' multiwavelength catalogues for Euclid Deep Field North and Euclid Deep Field Fornax
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LXII. Simulations and non-linearities beyond Lambda cold dark matter. 1. Numerical methods and validation
- Download full text (pdf) of Euclid preparation: LXII. Simulations and non-linearities beyond Lambda cold dark matter. 1. Numerical methods and validation
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Euclid preparation LIX. Angular power spectra from discrete observations
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation LIX. Angular power spectra from discrete observations
- Download full text (pdf) of Euclid preparation LIX. Angular power spectra from discrete observations
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Euclid preparation: LVI. Sensitivity to non-standard particle dark matter models
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LVI. Sensitivity to non-standard particle dark matter models
- Download full text (pdf) of Euclid preparation: LVI. Sensitivity to non-standard particle dark matter models
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Euclid preparation: LVIII. Detecting extragalactic globular clusters in the Euclid survey
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LVIII. Detecting extragalactic globular clusters in the Euclid survey
- Download full text (pdf) of Euclid preparation: LVIII. Detecting extragalactic globular clusters in the Euclid survey
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Part of Monthly notices of the Royal Astronomical Society, p. 1404-1429, 2025
- DOI for The XMM Cluster Survey: automating the estimation of hydrostatic mass for large samples of galaxy clusters - I. Methodology, validation, and application to the SDSSRM-XCS sample
- Download full text (pdf) of The XMM Cluster Survey: automating the estimation of hydrostatic mass for large samples of galaxy clusters - I. Methodology, validation, and application to the SDSSRM-XCS sample
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Euclid preparation: LX. The use of HST images as input for weak-lensing image simulations
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation: LX. The use of HST images as input for weak-lensing image simulations
- Download full text (pdf) of Euclid preparation: LX. The use of HST images as input for weak-lensing image simulations
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Euclid preparation LIV. Sensitivity to neutrino parameters
Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation LIV. Sensitivity to neutrino parameters
- Download full text (pdf) of Euclid preparation LIV. Sensitivity to neutrino parameters
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Part of Astronomy and Astrophysics, 2025
- DOI for Euclid preparation LV. Exploring the properties of proto-clusters in the Simulated Euclid Wide Survey
- Download full text (pdf) of Euclid preparation LV. Exploring the properties of proto-clusters in the Simulated Euclid Wide Survey
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Euclid preparation: L. Calibration of the halo linear bias in Î(v)CDM cosmologies
Part of Astronomy and Astrophysics, 2024
- DOI for Euclid preparation: L. Calibration of the halo linear bias in Î(v)CDM cosmologies
- Download full text (pdf) of Euclid preparation: L. Calibration of the halo linear bias in Î(v)CDM cosmologies
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Part of Astronomy and Astrophysics, 2024
- DOI for Euclid preparation: LI. Forecasting the recovery of galaxy physical properties and their relations with template-fitting and machine-learning methods
- Download full text (pdf) of Euclid preparation: LI. Forecasting the recovery of galaxy physical properties and their relations with template-fitting and machine-learning methods
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Part of Astronomy and Astrophysics, 2024
- DOI for Euclid preparation XLVII. Improving cosmological constraints using a new multi-tracer method with the spectroscopic and photometric samples
- Download full text (pdf) of Euclid preparation XLVII. Improving cosmological constraints using a new multi-tracer method with the spectroscopic and photometric samples
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Euclid preparation: XLVI. The near-infrared background dipole experiment with Euclid
Part of Astronomy and Astrophysics, 2024
- DOI for Euclid preparation: XLVI. The near-infrared background dipole experiment with Euclid
- Download full text (pdf) of Euclid preparation: XLVI. The near-infrared background dipole experiment with Euclid
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Part of Astronomy and Astrophysics, 2024
- DOI for Euclid preparation: XLV. Optical emission-line predictions of intermediate-z galaxy populations in GAEA for the Euclid Deep and Wide Surveys
- Download full text (pdf) of Euclid preparation: XLV. Optical emission-line predictions of intermediate-z galaxy populations in GAEA for the Euclid Deep and Wide Surveys
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Euclid preparation XLI. Galaxy power spectrum modelling in real space
Part of Astronomy and Astrophysics, 2024
- DOI for Euclid preparation XLI. Galaxy power spectrum modelling in real space
- Download full text (pdf) of Euclid preparation XLI. Galaxy power spectrum modelling in real space
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Part of Monthly notices of the Royal Astronomical Society, p. 5267-5290, 2023
- DOI for The XMM cluster survey: exploring scaling relations and completeness of the dark energy survey year 3 redMaPPer cluster catalogue
- Download full text (pdf) of The XMM cluster survey: exploring scaling relations and completeness of the dark energy survey year 3 redMaPPer cluster catalogue
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Euclid: Forecasts from redshift-space distortions and the Alcock-Paczynski test with cosmic voids
Part of Astronomy and Astrophysics, 2022
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Velocity dispersions of clusters in the Dark Energy Survey Y3 redMaPPer catalogue
Part of Monthly notices of the Royal Astronomical Society, p. 4696-4717, 2022
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Part of Monthly notices of the Royal Astronomical Society, p. 3030-3044, 2022
- DOI for Conditions for detecting lensed Population III galaxies in blind surveys with the James Webb Space Telescope, the Roman Space Telescope, and Euclid
- Download full text (pdf) of Conditions for detecting lensed Population III galaxies in blind surveys with the James Webb Space Telescope, the Roman Space Telescope, and Euclid
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Euclid: cosmological forecasts from the void size function
Part of Astronomy and Astrophysics, 2022
- DOI for Euclid: cosmological forecasts from the void size function
- Download full text (pdf) of Euclid: cosmological forecasts from the void size function
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Part of Monthly notices of the Royal Astronomical Society, p. 657-674, 2022
- DOI for The XMM Cluster Survey: an independent demonstration of the fidelity of the eFEDS galaxy cluster data products and implications for future studies
- Download full text (pdf) of The XMM Cluster Survey: an independent demonstration of the fidelity of the eFEDS galaxy cluster data products and implications for future studies
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Environmental dependence of X-ray and optical properties of galaxy clusters
Part of Monthly notices of the Royal Astronomical Society, p. 1953-1963, 2021
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Part of \mnras, p. 4591-4606, 2020
- DOI for Stellar mass as a galaxy cluster mass proxy: application to the Dark Energy Survey redMaPPer clusters
- Download full text (pdf) of Stellar mass as a galaxy cluster mass proxy: application to the Dark Energy Survey redMaPPer clusters
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Part of Publications Astronomical Society of Australia, 2020
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Part of Monthly notices of the Royal Astronomical Society, p. 855-870, 2020
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4MOST Consortium Survey 5: eROSITA Galaxy Cluster Redshift Survey
Part of The Messenger, p. 39-41, 2019
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4MOST: Project overview and information for the First Call for Proposals
Part of The Messenger, p. 3-11, 2019
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4MOST Consortium Survey 8: Cosmology Redshift Survey (CRS)
Part of The Messenger, p. 50-53, 2019
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Mass variance from archival X-ray properties of Dark Energy Survey Year-1 galaxy clusters
Part of Monthly notices of the Royal Astronomical Society, p. 3341-3354, 2019
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Part of Monthly notices of the Royal Astronomical Society, p. 1-17, 2019
- DOI for Galaxies in X-ray selected clusters and groups in Dark Energy Survey data - II. Hierarchical Bayesian modelling of the red-sequence galaxy luminosity function
- Download full text (pdf) of Galaxies in X-ray selected clusters and groups in Dark Energy Survey data - II. Hierarchical Bayesian modelling of the red-sequence galaxy luminosity function
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Dark Energy Surveyed Year 1 results: calibration of cluster mis-centring in the redMaPPer catalogues
Part of Monthly notices of the Royal Astronomical Society, p. 2578-2593, 2019
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Cluster-void degeneracy breaking: Neutrino properties and dark energy
Part of Physical Review D. Particles and fields, 2019
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Cluster-void degeneracy breaking: Modified gravity in the balance
Part of Physical Review D. Particles and fields, 2018
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The XXL survey: First results and future
Part of Astronomical Notes - Astronomische Nachrichten, p. 334-341, 2017
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Part of Montly notices of the royal astronomical society, p. 413-428, 2016
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The XMM Cluster Survey: the halo occupation number of BOSS galaxies in X-ray clusters
Part of Monthly notices of the Royal Astronomical Society, p. 1929-1943, 2016
Articles, review/survey
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Fundamental physics with the Square Kilometre Array
Part of Publications Astronomical Society of Australia, 2020
Chapters in book
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On Probability and Cosmology: Inference Beyond Data?
Part of The Philosophy of Cosmology, p. 429-446, Cambridge University Press, 2017