| Summary: | 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 parametrized 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.
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