Targeted gravitational-wave search for compact binaries using a GstLAL pipeline : Towards medium-latency followup.

The detection of the gravitational-wave signal from a binary neutron star system GW170817, accompanied by its electromagnetic counterpart, marked a historical breakthrough in multi-messenger astronomy. Despite this success, no subsequent multi-messenger observations have been recorded, and hence further optimization of such a joint search is of increasing interest. In this talk, we present an alternative approach to multi-messenger detection using a GW detection pipeline called GstLAL, where we follow up on the detection of electromagnetic signals with the GW search. In particular, we tune the signal consistency test that accounts for differences in arrival time and coalescence phase of GW candidates across different detectors such that the modified ranking statistic narrows down the signals coming from a specific location on the sky based on the electromagnetic signal being followed up. We conducted an injection campaign using signals originating from the same sky location, resulting in a O(10%) improvement in sensitivity with the new ranking statistic. We aim to reuse the database of GW candidates generated by low-latency GW all-sky search and produce counterpart candidates in medium-latency, potentially within a few hours of electromagnetic detection. We describe the promise and challenges to realize the medium-latency followup in the future.