Calibration Uncertainty of Advanced LIGO and its Effect on Parameter Estimation

Gravitational waves are ripples in spacetime that the LIGO Scientific Collaboration works to detect. Calibrating the data from these detectors is essential for analysis of the presence of gravitational-wave signals in the data. We improve the calibration of the LIGO detectors by tracking time dependent parameters. The cavity pole frequency is a time dependent parameter that characterizes a critical component in the detector and changes due to drift in the alignment and thermal state of the interferometer optics [1]. We studied how calibration error from the drifting cavity pole frequency affects our ability to extract information about how colliding neutron stars deform. The process of extracting the physics of the source from its gravitational waves is called parameter estimation (PE). To see how calibration uncertainty affects PE we modified the PE software to mimic the presence of calibration errors due to a drifting cavity pole frequency. We found that calibration error due to the drifting cavity pole frequency did not measurably bias recovered source parameters from PE. We also investigated the effect of total calibration error on PE and found no significant bias in measured parameters.