THE ATACAMA COSMOLOGY TELESCOPE: DR6 SUNYAEV-ZEL’DOVICH SELECTED GALAXY CLUSTERS CATALOG
Open Journal of Astrophysics 9 (2026)
Abstract:
We present the results of a search for galaxy clusters in the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) microwave sky maps covering 16293 square degrees in three frequency bands, using data obtained over the lifetime of the project (2008–2022). We report redshifts and mass estimates for 10040 clusters detected via their Sunyaev-Zel’dovich (SZ) effect with signal-to-noise greater than 4 at a 2.4 arcminute filter scale. The catalog includes 1180 clusters at redshifts greater than 1, and 124 clusters at redshifts greater than 1.5. Using a relation between cluster SZ signal and mass that is consistent with recent weak-lensing measurements, we estimate that clusters detected with signalto-noise greater than 5 form a sample which is 90% complete for clusters with masses greater than 5 × 1014M⊙ (measured within a spherical volume with mean density 500 times the critical density). El Gordo, a cluster found in an initial ACT survey of 755 square degrees, remains the most extreme cluster in mass and redshift; we find no cluster with a mass and redshift combination high enough to falsify the standard ΛCDM cosmology with Gaussian initial perturbations. We make public a variety of data products, including the full cluster candidate list, noise maps, and sky masks, along with our software for cluster detection and instructions for reproducing our cluster catalogs from the public ACT maps.
Probing baryonic feedback with fast radio bursts: joint analyses with cosmic shear and galaxy clustering
Monthly notices of the Royal Astronomical Society (2026)
Abstract:
Cosmological inference from weak lensing (WL) surveys is increasingly limited by uncertainties in baryonic physics, which suppress the non-linear matter power spectrum on small scales. Multi-probe analyses that incorporate complementary tracers of the gas distribution around haloes offer a pathway to calibrate these effects and recover unbiased cosmological information. In this work, we forecast the constraining power of a joint analysis combining fiducial data from a Stage-IV WL survey with measurements of the dispersion measure from fast radio bursts (FRBs). We evaluate the ability of this approach to simultaneously constrain cosmological parameters and the astrophysical processes governing baryonic feedback, and we quantify the impact of key FRB systematics, including redshift uncertainties and source clustering. We find that, even after accounting for these effects, a 3×2-point analysis of WL and FRBs significantly improves cosmological constraints, reducing the degradation factor on S8 by ∼80% compared to WL alone. We further show that FRBs alone are sensitive only to a degenerate combination of the key baryonic parameters, log10Mc and ηb, and that the inclusion of WL measurements breaks this degeneracy. Finally, we extend our framework to incorporate galaxy clustering measurements using Luminous Red Galaxy and Emission Line Galaxy samples, performing a unified 6×2-point analysis of WL, dispersion measures of FRBs, and galaxy clustering. While this combined approach tightens constraints on Ωm and log10Mc, it does not lead to a significant improvement in S8 constraints beyond those obtained from WL and FRBs alone.
A 15 Mpc rotating galaxy filament at redshift z = 0.032
Monthly Notices of the Royal Astronomical Society Oxford University Press 544:4 (2025) 4306-4316
Abstract:
Understanding the cold atomic hydrogen gas (H i) within cosmic filaments has the potential to pin down the relationship between the low density gas in the cosmic web and how the galaxies that lie within it grow using this material. We report the discovery of a cosmic filament using 14 H i-selected galaxies that form a very thin elongated structure of 1.7 Mpc. These galaxies are embedded within a much larger cosmic web filament, traced by optical galaxies, that spans at least Mpc. We find that the spin axes of the H i galaxies are significantly more strongly aligned with the cosmic web filament () than cosmological simulations predict, with the optically selected galaxies showing alignment to a lesser degree (). This structure demonstrates that within the cosmic filament, the angular momentum of galaxies is closely connected to the large-scale filamentary structure. We also find strong evidence that the galaxies are orbiting around the spine of the filament, making this one of the largest rotating structures discovered thus far, and from which we can infer that there is transfer of angular momentum from the filament to the individual galaxies. The abundance of H i galaxies along the filament and the low dynamical temperature of the galaxies within the filament indicates that this filament is at an early evolutionary stage where the imprint of cosmic matter flow on galaxies has been preserved over cosmic time.The Pandora project – II. How non-thermal physics drives bursty star formation and temperate mass-loaded outflows in dwarf galaxies
Monthly Notices of the Royal Astronomical Society Oxford University Press 545:2 (2025) staf2106
Abstract:
Dwarf galaxies provide powerful laboratories for studying galaxy formation physics. Their early assembly, shallow gravitational potentials, and bursty, clustered star formation histories make them especially sensitive to the processes that regulate baryons through multiphase outflows. Using high-resolution, cosmological zoom-in simulations of a dwarf galaxy from the Pandora suite, we explore the impact of stellar radiation, magnetic fields, and cosmic ray feedback on star formation, outflows, and metal retention. We find that our purely hydrodynamical model without non-thermal physics – in which supernova feedback is boosted to reproduce realistic stellar mass assembly – drives violent, overly enriched outflows that suppress the metal content of the host galaxy. Including radiation reduces the clustering of star formation and weakens feedback. However, the additional incorporation of cosmic rays produces fast, mass-loaded, multiphase outflows consisting of both ionized and neutral gas components, in better agreement with observations. These outflows, which entrain a denser, more temperate interstellar medium, exhibit broad metallicity distributions while preserving metals within the galaxy. Furthermore, the star formation history becomes more bursty, in agreement with recent James Webb Space Telescope findings. These results highlight the essential role of non-thermal physics in galaxy evolution and the need to incorporate it in future galaxy formation models.The JADES Origins Field: A New JWST Deep Field in the JADES Second NIRCam Data Release
The Astrophysical Journal: Supplement Series American Astronomical Society 281:2 (2025) 50