Inconsistent meaning of default for f_ref in LALSimulation inspiral routines.
Different inspiral waveform models in LALSimulation handle the f_ref
parameter differently:
- For some approximants, e.g.,
TaylorF2
,f_ref=0
means "at the end of the waveform" (~= at the peak time). - For some approximants, e.g.,
SEOBNRv4_ROM
,f_ref=0
effectively setsf_ref=f_min
.
This affects search pipelines when different IFOs are analyzed with different low frequency cutoffs. Then there can be an inconsistency in the interpretation of coalescence phase measured by the templates, which affects the measured phase difference between IFOs. This measured phase difference is now included in the search's ranking statistics.
It was suggested that conventions regarding the f_ref=0
default could be resolved as part of the
effort to standardize the convention for "coalescence time" as the peak in the 22-mode strain.