Constraining chameleon screening using galaxy cluster dynamics

Boumechta, Yacer; Haridasu, Balakrishna S.; Pizzuti, Lorenzo; Butt, Minahil Adil; Baccigalupi, C.; Lapi, A.

doi:10.1103/physrevd.108.044007

Cited by 4 publications

(4 citation statements)

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“…Constraints on the chameleon, symmetron and dilaton fields and respective particles can be obtained not only from the laboratory experiments mentioned above but from astrophysics and cosmology as well. One can mention constraints found from galaxy clusters' thermodynamic profiles, gravitational lensing and caustic techniques [85][86][87][88]. Specifically, the amplitude of the chameleon field and its coupling strength to matter were constrained by combining the gas and lensing measurements of the cluster [85].…”

Section: Constraints On the Particle Constituents Of Dark Energy From...mentioning

confidence: 99%

The Nature of Dark Energy and Constraints on Its Hypothetical Constituents from Force Measurements

Klimchitskaya,

Mostepanenko

2024

Universe

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This review considers the theoretical approaches to the understanding of dark energy, which comprises approximately 68% of the energy of our Universe and explains the acceleration in its expansion. Following a discussion of the main approach based on Einstein’s equations with the cosmological term, the explanations of dark energy using the concept of some kind of scalar field are elucidated. These include the concept of a quintessence and modifications of the general theory of relativity by means of the scalar–tensor gravity exploiting the chameleon, symmetron and environment-dependent dilaton fields and corresponding particles. After mentioning several laboratory experiments allowing us to constrain the hypothetical scalar fields modeling the dark energy, special attention is devoted to the possibility of constraining the parameters of chameleon, symmetron and environment-dependent dilaton fields from measuring the Casimir force. It is concluded that the parameters of each of these fields can be significantly strengthened in near future by using the next-generation setups in preparation suitable for measuring the Casimir force at larger separations.

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Section: Constraints On the Particle Constituents Of Dark Energy From...mentioning

confidence: 99%

The Nature of Dark Energy and Constraints on Its Hypothetical Constituents from Force Measurements

Klimchitskaya,

Mostepanenko

2024

Universe

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“…Another important property of the sample is that the hydrostatic equilibrium holds to a high accuracy, with at most mild levels on nonthermal pressure support in the outermost regions, as demonstrated by the analysis of [36,38]; this is particularly important, since nonthermal effects can appreciably affect the mass estimation in the outer regions [42,43] and potentially induce spurious effects in constraining modified gravity parameters [44]. All in all, X-COP is currently the largest cluster sample available so far for robust mass-modeling studies over an extended radial range, and as such it has been extensively exploited to probe modified-gravity scenarios [10][11][12][13].…”

Section: Bayesian Data Analysismentioning

confidence: 99%

“…The density n(r) and temperature T(r) distributions of the ICM throughout the cluster can be probed thanks to the copious X-ray powers L X ∝ n 2 √ T R 3 ∼ 10 44-46 erg s −1 emitted by the ICM via thermal Bremsstrahlung and high-excitation lines [3,4]. The inferred high average temperatures k B T ∼ several keVs and low average number densities n ∼ 10 −3 cm −3 make the ICM the best plasma in the Universe ever, with thermal to electrostatic energy ratios k B T/e 2 n 1/3 ∼ 10 12 .…”

Section: Introductionmentioning

confidence: 97%

“…Under this assumption, the gas density profile reconstructed from X-rays and the gas pressure profile from SZ data can be combined to probe the shape of the DM gravitational potential and check whether this is consistent with the DM density run extracted from N-body simulations in the ΛCDM cosmology. This is the rationale of many investigations aimed at exploiting galaxy clusters to probe modified gravity scenarios [7][8][9][10][11][12][13], which have been developed to solve cosmological problems such as the origin of dark energy [14][15][16], and/or to alleviate small-scales issues of the standard cold DM paradigm [17][18][19][20][21][22]. In the latter vein, a prototypical example of such theories is the modified Newtonian dynamics (MOND) framework, which was originally designed to explain galactic dynamics through a modification of Newtonian gravity (or, more generally, Newton's second law) that comes into action at accelerations well below a definite universal threshold; in its original formulation, DM was not included, and baryons were the only source of the gravitational field.…”

Section: Introductionmentioning

confidence: 99%

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Dark Matter in Fractional Gravity II: Tests in Galaxy Clusters

et al. 2023

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Recently, in Benetti et al. (Astrophys. J. 2023, 949, 65), we suggested that the dark matter (DM) component in galaxies may originate fractional gravity. In such a framework, the DM component exists, but the gravitational potential associated to its density distribution is determined by a modified Poisson equation including fractional derivatives (i.e., derivatives of noninteger type), which are meant to describe nonlocal effects; as such, this scenario is different from theories where baryonic matter emulates DM-like effects via modifications of gravity (e.g., MONDian frameworks). In Benetti et al., we showed that fractional gravity worked very well for reproducing the kinematics of disk-dominated galaxies, especially dwarfs; there is also preliminary evidence that the strength of fractional effects tends to weaken toward more massive systems. Here, we aim to test fractional gravity in galaxy clusters, with a twofold aim: (i) perform an independent sanity check that it can accurately describe such large and massive structures; (ii) derive a clear-cut trend for its strength in systems with different DM masses. To this purpose, we forward model the density and pressure distributions of the intracluster medium (ICM), working out the hydrostatic equilibrium equation in fractional gravity. Then, we perform a Bayesian analysis of the X-COP galaxy cluster sample and infer constraints on the fractional gravity parameters, for individual clusters as well as stacked clusters. We find that fractional gravity performs remarkably well in modeling the ICM profiles for the X-COP sample. We also check that the DM concentration vs. mass relation is still consistent with the expectations of N-body simulations in the standard cosmological scenario. Finally, we confirm the weakening of the fractional gravity effects toward more massive systems and derive the overall scaling of the fractional gravity parameters from dwarf galaxies to massive clusters, spanning six orders of magnitude in DM mass. Such an overall trend implies that fractional gravity can substantially alleviate the small-scale issues of the standard DM paradigm, while remaining successful on large cosmological scales.

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