Testing emergent gravity on galaxy cluster scales

Tamosiunas, Andrius; Bacon, David; Koyama, K.; Nichol, R. C.

doi:10.1088/1475-7516/2019/05/053

Cited by 19 publications

(13 citation statements)

References 34 publications

(94 reference statements)

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“…Using two relaxed clusters (A2142 and A2319), they found that EG underpredicts the apparent DM mass by a factor of up to a few in the innermost regions of the cluster, but the prediction improved as a function of increasing radius until ∼ r 500 , where the EG prediction and the DM mass estimated from hydrostatic equilibrium matched. Similar trends were noticed by other authors for a number of other systems Halenka et al 2018;Tamosiunas et al 2019).…”

supporting

confidence: 91%

Testing Emergent Gravity with Optical, X-Ray, and Weak Lensing Measurements in Massive, Relaxed Galaxy Clusters

ZuHone

Sims²

2019

ApJ

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We test the predictions of Emergent Gravity using matter densities of relaxed, massive clusters of galaxies using observations from optical and X-ray wavebands. We improve upon previous work in this area by including the baryon mass contribution of the brightest cluster galaxy in each system, in addition to total mass profiles from gravitational lensing and mass profiles of the X-ray emitting gas from Chandra. We use this data in the context of Emergent Gravity to predict the "apparent" dark matter distribution from the observed baryon distribution, and vice-versa. We find that although the inclusion of the brightest cluster galaxy in the analysis improves the agreement with observations in the inner regions of the clusters (r ∼ < 10 − 30 kpc), at larger radii (r ∼ 100 − 200 kpc) the Emergent Gravity predictions for mass profiles and baryon mass fractions are discrepant with observations by a factor of up to ∼ 2 − 6, though the agreement improves at radii near r 500 . At least in its current form, Emergent Gravity does not appear to reproduce the observed characteristics of relaxed galaxy clusters as well as cold dark matter models.

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supporting

confidence: 91%

Testing Emergent Gravity with Optical, X-Ray, and Weak Lensing Measurements in Massive, Relaxed Galaxy Clusters

ZuHone

Sims²

2019

ApJ

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“…5 that LoCuSS (Mulroy et al 2019) results (0.15 < z < 0.3) are in significant tension with Capasso et al (2019). These results, if confirmed, could be used to constrain the models of modified gravity (Arnold, Puchwein & Springel 2014;Sakstein et al 2016;Wilcox et al 2016;Mitchell et al 2018;Tamosiunas et al 2019). Improvements in spectroscopic follow-up of high-z clusters is, however, very critical.…”

Section: R E S U Lt S a N D Discussionmentioning

confidence: 72%

CODEX weak lensing mass catalogue and implications on the mass–richness relation

Kiiveri

Finoguenov

Erben

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The COnstrain Dark Energy with X-ray clusters (CODEX) sample contains the largest flux limited sample of X-ray clusters at 0.35 < z < 0.65. It was selected from ROSAT data in the 10 000 square degrees of overlap with BOSS, mapping a total number of 2770 high-z galaxy clusters. We present here the full results of the CFHT CODEX programme on cluster mass measurement, including a reanalysis of CFHTLS Wide data, with 25 individual lensing-constrained cluster masses. We employ lensfit shape measurement and perform a conservative colour–space selection and weighting of background galaxies. Using the combination of shape noise and an analytic covariance for intrinsic variations of cluster profiles at fixed mass due to large-scale structure, miscentring, and variations in concentration and ellipticity, we determine the likelihood of the observed shear signal as a function of true mass for each cluster. We combine 25 individual cluster mass likelihoods in a Bayesian hierarchical scheme with the inclusion of optical and X-ray selection functions to derive constraints on the slope α, normalization β, and scatter σln λ|μ of our richness–mass scaling relation model in log-space: ${\langle {\rm In}\,\, \lambda\!\!\mid\!\!\mu\rangle = \alpha\mu + \beta,} $ with μ = ln (M200c/Mpiv), and Mpiv = 1014.81M⊙. We find a slope $\alpha = 0.49^{+0.20}_{-0.15}$, normalization $\exp (\beta) = 84.0^{+9.2}_{-14.8}$, and $\sigma _{\ln \lambda | \mu } = 0.17^{+0.13}_{-0.09}$ using CFHT richness estimates. In comparison to other weak lensing richness–mass relations, we find the normalization of the richness statistically agreeing with the normalization of other scaling relations from a broad redshift range (0.0 < z < 0.65) and with different cluster selection (X-ray, Sunyaev–Zeldovich, and optical).

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“…Likewise, the ability of measuring cluster masses in different ways (e.g. X-ray astronomy, weak lensing and the Sunyaev-Zeldovich effect) has been explored as a powerful tool for constraining various modified gravity models [11,[24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Chameleon Screening Depends on the Shape and Structure of NFW Halos

Tamosiunas,

Briddon,

Burrage

et al. 2021

Preprint

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Chameleon gravity is an example of a model that gives rise to interesting phenomenology on cosmological scales while simultaneously possessing a screening mechanism, allowing it to avoid solar system constraints. Such models result in non-linear field equations, which can be solved analytically only in simple highly symmetric systems. In this work we study the equation of motion of a scalar-tensor theory with chameleon screening using the finite element method. More specifically, we solve the field equation for spherical and triaxial NFW cluster-sized halos. This allows a detailed investigation of the relationship between the NFW concentration and the virial mass parameters and the magnitude of the chameleon acceleration, as measured at the virial radius. In addition, we investigate the effects on the chameleon acceleration due to halo triaxiality. We focus on the parameter space regions that are still allowed by the observational constraints. We find that given our dataset, the largest allowed value for the chameleon-to-NFW acceleration ratio at the virial radius is ∼ 10 −7 . This result strongly indicates that the chameleon models that are still allowed by the observational constraints would not lead to any measurable effects on galaxy cluster scales. Nonetheless, we also find that there is a direct relationship between the NFW potential and the chameleonto-NFW acceleration ratio at the virial radius. Similarly, there is a direct (yet a much more complicated) relationship between the NFW concentration, the virial mass and the acceleration ratios at the virial radius. Finally, we find that triaxiality introduces extra directional effects on the acceleration measurements. These effects in combination could potentially be used in future observational searches for fifth forces.

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Testing emergent gravity on galaxy cluster scales

Cited by 19 publications

References 34 publications

Testing Emergent Gravity with Optical, X-Ray, and Weak Lensing Measurements in Massive, Relaxed Galaxy Clusters

Testing Emergent Gravity with Optical, X-Ray, and Weak Lensing Measurements in Massive, Relaxed Galaxy Clusters

CODEX weak lensing mass catalogue and implications on the mass–richness relation

Chameleon Screening Depends on the Shape and Structure of NFW Halos

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