The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000

Abstract

We present measurements of the radial gravitational acceleration around isolated galaxies, comparing the expected gravitational acceleration given the baryonic matter (gbar) with the observed gravitational acceleration (gobs), using weak lensing measurements from the fourth data release of the Kilo-Degree Survey (KiDS-1000). These measurements extend the radial acceleration relation (RAR), traditionally measured using galaxy rotation curves, by 2 decades in gobs into the low-acceleration regime beyond the outskirts of the observable galaxy. We compare our RAR measurements to the predictions of two modified gravity (MG) theories: modified Newtonian dynamics and Verlinde’s emergent gravity (EG). We find that the measured relation between gobs and gbar agrees well with the MG predictions. In addition, we find a difference of at least 6σ between the RARs of early- and late-type galaxies (split by Sérsic index and u − r colour) with the same stellar mass. Current MG theories involve a gravity modification that is independent of other galaxy properties, which would be unable to explain this behaviour, although the EG theory is still limited to spherically symmetric static mass models. The difference might be explained if only the early-type galaxies have significant (Mgas ≈ M⋆) circumgalactic gaseous haloes. The observed behaviour is also expected in Λ-cold dark matter (ΛCDM) models where the galaxy-to-halo mass relation depends on the galaxy formation history. We find that MICE, a ΛCDM simulation with hybrid halo occupation distribution modelling and abundance matching, reproduces the observed RAR but significantly differs from BAHAMAS, a hydrodynamical cosmological galaxy formation simulation. Our results are sensitive to the amount of circumgalactic gas; current observational constraints indicate that the resulting corrections are likely moderate. Measurements of the lensing RAR with future cosmological surveys (such as Euclid) will be able to further distinguish between MG and ΛCDM models if systematic uncertainties in the baryonic mass distribution around galaxies are reduced.

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“…shed more light on the deep nature of gravitation, or are they just obscuring some cosmological phenomena, such as the accelerated expansion of our Universe by presupposing the non-observable dark matter? Evidence for dark matter claims to explain excess gravity is supported by recent references (Brouwer et al, 2021). However, in this study, measurements of hydrogen profiles beyond and within the optical discs of galaxies, dynamics of galaxies in clusters, and other new methods such as weak gravitational lensing, only demonstrate baryon acoustic oscillations and cosmic microwave oscillations.…”

“…However, in this study, measurements of hydrogen profiles beyond and within the optical discs of galaxies, dynamics of galaxies in clusters, and other new methods such as weak gravitational lensing, only demonstrate baryon acoustic oscillations and cosmic microwave oscillations. What is more, Brouwer et al (2021) provided more evidence for Milgrom's non-general relativistic Modified Newtonian Dynamics (Milgrom, 1983(Milgrom, , 2013, although the experimental support discloses the a priori conditions of observability rather than shedding light on the essential nature of mass and gravitation. These attempts, based on the equivalence principle of gravitation and inertia, discover the extrinsic characters of the entire Universal Event, but they do not disclose the deep essence of intrinsic characters such as mass and gravitation.…”

The Kennicutt-Schmidt law and the main sequence of galaxies in Newtonian and Milgromian dynamics

“…MOND predicted the very tight radial acceleration relation (RAR) between the gravity 𝑔 implied by disc galaxy rotation curves and the Newtonian gravity 𝑔 N resulting from their baryonic distribution (Lelli et al 2017;Li et al 2018). The RAR is also evident in stacked galaxy-galaxy weak lensing measurements that probe out to larger radii (Milgrom 2013;Brouwer et al 2021). The external field effect (EFE) predicted by MOND (Bekenstein & Milgrom 1984) and required for consistency with data on Solar neighbourhood wide binaries (Banik & Zhao 2018c; Pittordis & Sutherland 2019) has recently been confirmed at high significance by comparing galaxies in isolated and more crowded environments (Haghi et al 2016;Chae et al 2020).…”

Probing modified gravity with magnetically levitated resonators

“…In addition, modifications to Newton's second law of dynamics F = ma, especially in the regime of low accelerations such as in the MOdified Newtonian Dynamics (MOND) theory [6], have been proposed as valid alternatives to dark matter [7] to explain, among other observables, the flat rotation curves of galaxies. In the astrophysical community MOND is considered a viable possibility to reproduce a number of galactic observables [8]. Recently, Milgrom has claimed that MOND can reproduce the full scaling of the angular momentum of disc galaxies as a function of galaxy mass [9].…”