Galaxy cluster counts from eRASS1 plus weak lensing data set the tightest existing upper bounds on ultralight axion relic density Ω_a around 10^{-27} eV (Ω_a < 0.0035) and 10^{-26} eV (Ω_a < 0.0079) at 95% CL.
2024a, arXiv e-prints
4 Pith papers cite this work. Polarity classification is still indexing.
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abstract
Beyond testing the current cosmological paradigm, cluster number counts can also be utilized to investigate the discrepancies currently affecting current cosmological measurements. In particular, cosmological studies based on cosmic shear and other large-scale structure probes routinely find a value of the amplitude of the fluctuations in the universe S8 smaller than the one inferred from the primary cosmic microwave background. In this work, we investigate this tension by measuring structure evolution across cosmic time as probed by the number counts of the massive halos with the first SRG/eROSITA All-Sky Survey cluster catalog in the Western Galactic Hemisphere complemented with the overlapping Dark Energy Survey Year-3, KiloDegree Survey, and Hyper Suprime-Cam data for weak lensing mass calibration, by implementing two different parameterizations and a model-agnostic method. In the first model, we measure the cosmic linear growth index as {\gamma} = 1.19 \pm 0.21, in tension with the standard value of {\gamma} = 0.55, but in good statistical agreement with other large-scale structures probes. The second model is a phenomenological scenario in which we rescale the linear matter power spectrum at low redshift to investigate a potential reduction of structure formation, providing similar results. Finally, in a third strategy, we consider a standard {\Lambda}CDM cosmology, but we separate the cluster catalog into five redshift bins, measuring the cosmological parameters in each and inferring the evolution of the structure formation, finding hints of a reduction. Interestingly, the S8 value inferred from eRASS1 cluster number counts, when we add a degree of freedom to the matter power spectrum, recovers the value inferred by cosmic shear studies.
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astro-ph.CO 4representative citing papers
VLSS J0318.9+5755 (the Treble Clef) is a radio phoenix with ultra-steep spectrum in a massive merging cluster at z≈0.117 in the Zone of Avoidance, shaped by ICM gas motions that may also power a candidate radio halo.
Fixing the covariance at an incorrect cosmology in cluster count analyses leaves Ω_c, σ_8, and w estimates unbiased but distorts their uncertainties, driven by S_8 amplitude effects; a single update at the recovered best-fit cosmology restores correct normalization for LSST-like surveys.
Combining gravitational-potential decay-rate (DR) data with Σ8 and fσ8 growth measurements tightens modified-gravity parameter constraints by ~1.5–2×, with all results consistent with general relativity.
citing papers explorer
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The SRG/eROSITA all-sky survey: Constraints on Ultra-light Axion Dark Matter through Galaxy Cluster Number Counts
Galaxy cluster counts from eRASS1 plus weak lensing data set the tightest existing upper bounds on ultralight axion relic density Ω_a around 10^{-27} eV (Ω_a < 0.0035) and 10^{-26} eV (Ω_a < 0.0079) at 95% CL.
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The Treble Clef radio phoenix and its old nonthermal filaments
VLSS J0318.9+5755 (the Treble Clef) is a radio phoenix with ultra-steep spectrum in a massive merging cluster at z≈0.117 in the Zone of Avoidance, shaped by ICM gas motions that may also power a candidate radio halo.
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Cosmology-dependent covariance in galaxy cluster number counts: consequences for parameter inference
Fixing the covariance at an incorrect cosmology in cluster count analyses leaves Ω_c, σ_8, and w estimates unbiased but distorts their uncertainties, driven by S_8 amplitude effects; a single update at the recovered best-fit cosmology restores correct normalization for LSST-like surveys.
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Synergy between the gravitational potential decay rate and other structure growth probes in testing gravity
Combining gravitational-potential decay-rate (DR) data with Σ8 and fσ8 growth measurements tightens modified-gravity parameter constraints by ~1.5–2×, with all results consistent with general relativity.