Maximum Likelihood threshold

#1
Dear all,
I'm an astrophysicist and I'm working with a code computing the
maximum likelihood of finding a galaxy cluster in a certain point of
the sky given a model and a distribution of galaxies. I would like to
find a treshold that corrisponds to a N-sigma detection...is it
possible to define it statistically? I mean, does it exist something
equivalent t the chi square distribution for the maximum likelihood,
that translate a certain likelihood value in a "confidence limit"?
Thanks!
cheers
Stefania