f(R) gravity constraints from gravitational waves
  The recent LIGO observation sparked interest in the field of gravity wave
signals. Besides the gravity wave observation the LIGO collaboration used the
inspiraling black hole pair to constrain the graviton mass. Unlike general
relativity, $f(R)$ theories have a characteristic non-zero mass graviton. We
apply the constraint on the graviton mass to viable $f(R)$ models to find the
effects on model parameters. We find it possible to constrain the parameter
space with the gravity wave based observations. We make a case study for the
popular Hu-Sawicki model and find a parameter bracket. The result generalizes
to other $f(R)$ theories and can be used to contain the parameter space.
