Diagnosing the Tomte glitch

Hi everyone!

Recently, some of LIGO’s detchar experts investigated the connection between Tomte glitches from Gravity Spy and the bias voltage on a particular circuit. You can read the full alog of this investigation here. Below is a summary written by TJ Massinger, one of the detchar experts who does a lot of work with Gravity Spy data!

During recent commissioning work at the LIGO Livingston Observatory, it was noticed that glitches were occurring while the bias voltage on a circuit (an electrostatic actuator) was adjusted. Inspection of these glitches using the same time-frequency visualization that Gravity Spy uses showed that they looked qualitatively similar to glitches classified by users as the “tomte” class.

Spectrogram of an ESD bias ramping glitch. 

Using the GravitySpy classifier, it was found that these recent glitches are also classified as tomte glitches. To quantify the similarity of the bias voltage glitches to the tomte glitches seen in the second observing run (O2), GravitySpy was used to gather a collection of previously identified tomte glitches in O2 with parameters similar to those seen when adjusting the bias voltage. Upon comparing these populations, their time- and frequency-domain morphology was found to be nearly identical, suggesting that the population of tomte glitches in O2 might be understood by continuing to investigate the glitches that occur when adjusting bias voltages.

Tomte rate in O2 based on Gravity Spy classifications with greater than 90% confidence.