Mass Screening in Modified Gravity

TL;DR

This paper investigates how nonlinear interactions in modified gravity models create halos around massive objects, screening their gravitational influence and potentially challenging the models' observational viability.

Contribution

It highlights the dual role of halos in both shielding extra degrees of freedom and screening gravitational mass, providing new insights into the observational implications of modified gravity.

Findings

Halos can significantly suppress gravitational effects of massive objects.

Screening effects may invalidate or constrain certain modified gravity models.

Nonlinear interactions are crucial for understanding observable signatures.

Abstract

Models of modified gravity introduce extra degrees of freedom, which for consistency with the data, should be suppressed at observable scales. In the models that share properties of massive gravity such a suppression is due to nonlinear interactions: An isolated massive astrophysical object creates a halo of a nonzero curvature around it, shielding its vicinity from the influence of the extra degrees of freedom. We emphasize that the very same halo leads to a screening of the gravitational mass of the object, as seen by an observer beyond the halo. We discuss the case when the screening could be very significant and may rule out, or render the models observationally interesting.