Monopole radiation in modified gravity
  Modifications to General Relativity typically introduce a scalar degree of
freedom. Experimental constraints require that the "fifth" force produced by
this field must be screened in high density environments. An important
consequence of the screening mechanism is that the scalar charge of a
spherically symmetric expanding or pulsating object, such as a supernova or
variable star, is not conserved and monopole radiation can be emitted thereby.
We calculate the energy loss rate due to scalar monopole radiation in
supernovae and variable stars for a generalized model of f(R) gravity in which
the matter coupling strength beta is allowed to be much larger than unity. For
models which become screened at the gravitational potential of our galaxy,
monopole radiation constraints require beta < 100.
