  The last decade has seen great advancements in the field of modified gravity,
motivated by the dark energy problem, or by the search for a fundamental
quantum gravity theory. With a phenomenologically-driven approach, we consider
dRGT theory and its extension, quasi-dilaton massive gravity (QDMG). When
looking for ways to constrain the theory, a promising direction appeared to be
astrophysical tests. The scalar gravitational degree of freedom and
quasi-dilaton degree of freedom alter the evolution of Bardeen potentials,
which in turn affects the galaxy rotation curves. We find an upper bound on
graviton mass in QDMG to be $m \leq 10^{-31} {\rm eV}$. This result agrees with
bounds from LIGO and numerous Solar System tests. However, the extremely small
mass of the graviton remains a detection out of reach, with LISA's sensitivity
exploring the parameter space up to $m \leq 10^{-25} {\rm eV}$.

General Relativity and Quantum Cosmology;Astrophysics of Galaxies