  According to General Relativity a perturbed black hole will return to a
stable configuration by the emission of gravitational radiation in a
superposition of quasi-normal modes. Such a perturbation will occur due to the
coalescence of a black hole binary, following their inspiral and subsequent
merger. At late times the waveform, which we refer to as a ringdown, is
expected to be dominated by a single mode. As the waveform is well-known the
method of matched filtering can be implemented to search for this signal using
LIGO data. LIGO is sensitive to the dominant mode of perturbed black holes with
masses between 10 and 500 M_sun, the regime of intermediate-mass black holes,
to a distance of up to 300 Mpc. We present a search for gravitational waves
from black hole ringdowns using data from the fourth LIGO science run. We
implement a blind analysis of the data. We use Monte Carlo simulations of the
expected waveform, and an estimation of the background from timeslides to tune
the search. We present an analysis of the waveform parameter estimation and
estimate the efficiency of the search. As there were no gravitational wave
candidates found, we place an upper limit on the rate of black hole ringdowns
in the local universe.
