Search setup for long-duration transient gravitational waves from glitching pulsars during LIGO-Virgo third observing run

Abstract

Pulsars are spinning neutron stars which emit an electromagnetic beam. We expect pulsars to slowly decrease their rotational frequency. However, sudden increases of the rotational frequency have been observed from different pulsars. These events are called "glitches" and they are followed by a relaxation phase with timescales from days to months. Gravitational wave (GW) emission may follow these peculiar events. We give an overview of the setup for an analysis of GW data from the Advanced LIGO and Virgo third observing run (O3) [1] searching for transient GW signals lasting hours to months after glitches in known pulsars. The search method consists of placing a template grid in frequency-spindown space with fixed grid spacings. Then, for each point we compute the transient F-statistic which is maximized over a set of transient parameters like the duration and start time of the potential signals. A threshold on the detection statistic is then set, and we search for peaks over the parameter space for each candidate.

Empirically estimating the distribution of the loudest candidate from a gravitational-wave search

“…No simple amendment, other than using a higher mismatch [10,53], is currently available to obtain robust results with distromax in this situation. This phenomenon was observed in [90,91], where distromax was applied to process the result of both a search for CW signals and a search for long-duration transient GWs from glitching pulsars. The CW search used a mismatch of m ≃ 0.02 combined with a toplist, which reduced the effect of such a dense parameter-space converging on the batchmax distribution.…”

Status and Perspectives of Continuous Gravitational Wave Searches

“…Results from an additional search for long-duration transient GWs after pulsar glitches are also reported in [240]. Six targets have been investigated by the long-transient search, performed using the transient F-statistic method [185,241]. For these six sources, showing a total of nine glitches, an independent long-transient search is performed after each glitch.…”