Gravitational alternatives to dark matter with tensor mode speed equaling the speed of light

Skordis, Constantinos; Złośnik, Tom

doi:10.1103/physrevd.100.104013

Cited by 63 publications

(59 citation statements)

References 75 publications

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“…We will discuss the main features of MOND in Section 2.1. Its unique relativistic completion (sometimes dubbed FUNDAMOND) is still unknown, though the recently developed theory of Skordis & Z lośnik (2019) is promising because the model predicts that tensor mode gravitational waves propagate at the speed of light c, even in the presence of structure. Moreover, it can in principle provide a term decoupled from the baryon-photon plasma in the early Universe to explain the CMB angular power spectrum and obtain a standard late-time matter power spectrum (Skordis & Z losnik 2020).…”

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confidence: 99%

Barred spiral galaxies in modified gravity theories

Roshan

Banik

Ghafourian

et al. 2021

Monthly Notices of the Royal Astronomical Society

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When bars form within galaxy formation simulations in the standard cosmological context, dynamical friction with dark matter (DM) causes them to rotate rather slowly. However, almost all observed galactic bars are fast in terms of the ratio between corotation radius and bar length. Here, we explicitly display an 8σ tension between the observed distribution of this ratio and that in the EAGLE simulation at redshift 0. We also compare the evolution of Newtonian galactic discs embedded in DM haloes to their evolution in three extended gravity theories: Milgromian Dynamics (MOND), a model of non-local gravity, and a scalar-tensor-vector gravity theory (MOG). Although our models start with the same initial baryonic distribution and rotation curve, the long-term evolution is different. The bar instability happens more violently in MOND compared to the other models. There are some common features between the extended gravity models, in particular the negligible role played by dynamical friction − which plays a key role in the DM model. Partly for this reason, all extended gravity models predict weaker bars and faster bar pattern speeds compared to the DM case. Although the absence of strong bars in our idealized, isolated extended gravity simulations is in tension with observations, they reproduce the strong observational preference for ‘fast’ bar pattern speeds, which we could not do with DM. We confirm previous findings that apparently ‘ultrafast’ bars can be due to bar-spiral arm alignment leading to an overestimated bar length, especially in extended gravity scenarios where the bar is already fast.

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confidence: 99%

Barred spiral galaxies in modified gravity theories

Roshan

Banik

Ghafourian

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…TeVeS in particular can be compatible with the MPS of large scale structure 103,104 but fails to fit the CMB. Moreover, it leads to a tensor mode gravitational wave (GW) speed different than the speed of light, 105 in contradiction with the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo observations of GW along with an electromagnetic counterpart.…”

Section: New Gravitational Degrees Of Freedom and The Dm Problemmentioning

confidence: 84%

Cosmic backgrounds from the radio to the far-infrared: recent results and perspectives from cosmological and astrophysical surveys

Burigana,

Battistelli,

Bonavera

et al. 2021

Preprint

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Cosmological and astrophysical surveys in various wavebands, in particular from the radio to the far-infrared, offer a unique view of the universe's properties and the formation and evolution of its structures. After a preamble on the so-called tension problem, which occurs when different types of data are used to determine cosmological parameters, we discuss the role of fast radio bursts in cosmology, in particular for the missing baryon problem, and the perspectives from the analysis of the 21 cm redshifted line from neutral * Based on talks presented at the Sixteenth Marcel Grossmann Meeting on General Relativity, July 2021.

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“…And although the MOND crossover acceleration, a 0 , seems to differ when the analysis is done at galactic or at cluster scales, a reappraisal of the systematic errors in the cluster mass profiles (Ettori et al 2019), and hybrid models with neutrinos as hot dark matter (Angus 2009;Haslbauer et al 2020) could alleviate this tension. Looking for a field-theoretical expression, initial versions proposed for MOND, such as TeVeS (Bekenstein 2004), were recently ruled out by the multi-messenger observations of GW170817, but a slightly modified form passes this test (Skordis & Złośnik 2019). Possible links between MOND and cosmology include the entropic expression of gravity (Pazy 2013), emergent gravity (Verlinde 2017), mimetic gravity (Vagnozzi 2017) or some expressions of quantum gravity (Smolin 2017).…”

Section: Introductionmentioning

confidence: 99%

MOND-like behavior in the Dirac–Milne universe

Chardin

Dubois

Manfredi

et al. 2021

A&A

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Aims. Observational data show that the observed luminous matter is not sufficient to explain several features of the present universe, from gravitational structure formation to the rotational velocities in galaxies and clusters. The mainstream explanation is that the missing mass, although gravitationally active, interacts very weakly with ordinary matter. Competing explanations involve changing the laws of gravity at low accelerations, as in MOdified Newtonian Dynamics (MOND). Here, we suggest that the Dirac-Milne cosmology, a matter-antimatter symmetric cosmology where the two components repel each other, is capable of accounting for such an apparent modification of the Newtonian law, without invoking dark matter. Methods. Using a simple analytical approximation and 1D and 3D simulations, we study rotation curves and virial velocities and compare the mass observed in the simulations to the mass derived assuming Newtonian gravity. Using a modified version of the RAMSES code, we study the Faber-Jackson scaling relation and the intensity of the additional gravitational field created by antimatter clouds. Results. We show that, in the Dirac-Milne universe, rotation curves are generically flat beyond a characteristic distance of ≈2.5 virial radii, and that the Tully-Fisher and Faber-Jackson scaling relations with an exponent ≈3 are satisfied. We show that the mass derived from the rotation curves assuming Newtonian gravity is systematically overestimated compared to the mass really present. In addition, the Dirac-Milne universe, featuring a polarization between its matter and antimatter components, presents a behavior similar to that of MOND, characterized by an additional surface gravity compared to the Newtonian case. We show that in the Dirac-Milne universe, at the present epoch, the intensity of the additional gravitational field gam due to the presence of clouds of antimatter is on the order of a few 10−11 m s−2, similar to the characteristic acceleration of MOND. We study the evolution of this additional acceleration gam and show that it depends on the redshift, and it is therefore not a fundamental constant. Conclusions. Combined with its known concordance properties on the SNIa luminosity distance, age, nucleosynthesis, and structure formation, the Dirac-Milne cosmology may then represent an interesting alternative to the standard cosmological model ΛCDM, MOND, and other scenarios for explaining the dark matter (or missing gravity) and dark energy conundrum.

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Gravitational alternatives to dark matter with tensor mode speed equaling the speed of light

Cited by 63 publications

References 75 publications

Barred spiral galaxies in modified gravity theories

Barred spiral galaxies in modified gravity theories

Cosmic backgrounds from the radio to the far-infrared: recent results and perspectives from cosmological and astrophysical surveys

MOND-like behavior in the Dirac–Milne universe

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