# Ringdown Waveforms¶

Minke is capable of producing signals which are based on waveforms based on Binary Black Hole (BBH) ringdowns.

Ringdown-like signals, with a sudden rise, and exponential decay in amplitude are expected in the post-merger signal of CBC systems, and in some models of neutron star model excitation [2004PhRvD..70l4015B].

These take the form

$h(t) = \exp (-t / \tau) \sin( 2 \pi f t)$

for a strain $$h$$ at time $$t$$, given a decay time $$\tau$$ and frequency $$f$$.

## BBHRingdown¶

The BBH Ringdown class in the sources module follows a similar style to other source classes within minke. To produce a single ringdown waveform:

>>> import minke.sources
>>> bbh = minke.sources.BBHRingdown(100.23, 1e-22, np.rad2deg(.1), 10., 0.97, 0.01, 1.0,45.)


then the waveforms themselves can be produced by running

>>> hp, hx, _, _ = bbh._generate()


The waveform will be generated at the LIGO sampling rate (16384 Hz) by default, but this can be changed by specifying a rate keyword. The waveforms are also generated for the (2,2) mode by default, but by adding l and m keywords to the _generate() method this can also be changed.

class minke.sources.BBHRingdown(time, phi0, mass, spin, massloss, distance, inclination, sky_dist=<function uniform_sky>)[source]

A class to represent BBH ringdowns.

Methods

 generate_tail(self[, sampling, length, …]) Generate a “low frequency tail” to append to the end of the waveform to overcome problems related to memory in the waveform. interpolate(self, x_old, y_old, x_new[, method]) Convenience funtion to avoid repeated code parse_polarisation(self, polarisation) Convert a string description of a polarisation to an ellipse eccentricity and an ellipse angle. plot(self[, figsize]) Produce a plot of the injection. table_type alias of glue.ligolw.lsctables.SimRingdownTable