Screened fifth forces mediated by dark matter-baryon interactions: Theory and astrophysical probes

Abstract

We derive the details of a new screening mechanism where the interactions of baryons and dark matter can be screened according to the local dark matter density. In this mechanism, the value of Newton's constant is dark matter density-dependent, allowing for the possibility that astrophysical phenomena are very different in galaxies less dense than the Milky Way. The parameterized post Newtonian parameter γ, which quantifies the difference between kinematical and lensing probes, also depends on dark matter density. We calculate the effects of varying G on various stages of stellar evolution, focusing on observables that impact cosmology: the Cepheid period-luminosity relation and the supernova Ia magnitude-redshift relation. Other potential tests of the model are also investigated including main-sequence, post-main sequence, and low mass dwarf stars. Finally, we discuss how extragalactic tests of γ could provide complementary constraints. Recently, the authors of Ref. [30] have devised a dark energy model where the cosmic acceleration is driven not arXiv:1907.03775v1 [astro-ph.CO]

Beyond the Standard Model Explanations of GW190521

“…Modified gravity theories are able to simultaneously drive the acceleration of the cosmic expansion (dark energy) while remaining compatible with solar system tests of gravity [44][45][46][47]. They are also leading candidates for explaining the Hubble tension [48][49][50]. Their success is due to screening mechanisms, which suppress fifth forces in high density environments.…”

Time-dependent G in Einstein’s equations as an alternative to the cosmological constant

“…Their numerical relation is converted to an approximate expression in Ref. [23] as L ∝ G 1.46 . Since there is no consensus on the precise nature of supernovae physics, as a second case we also use the distance modulus derived from this luminosity-G dependence:…”

Novel Probes Project: Tests of gravity on astrophysical scales

“…1) or acceleration, for example. Recently Sakstein, Desmond, and Jain (2019) identified a new screening mechanism that screens fifth forces mediated by interactions between dark matter and baryons. They suggest several astrophysical tests that merit further investigation.…”

“…This coupling could lead to cosmic acceleration at late times (Berezhiani, Khoury, and Wang, 2017;Ferreira et al, 2018). Sakstein, Desmond, and Jain (2019) investigated this model and showed that it contains a novel screening mechanism where the value of Newton's constant can vary depending on the local dark matter density. They also list further potential astrophysical tests that could prove fruitful once the theory is developed; see also Desmond, Jain, and Sakstein (2019) and Desmond and Sakstein (2020).…”

“…Further discussion of the effect of fifth forces on stars was given by Sakstein, Desmond, and Jain (2019).…”