J-GEM optical and near-infrared follow-up of gravitational wave events during LIGO's and Virgo's third observing run

TL;DR

J-GEM conducted optical and near-infrared follow-up observations of 23 gravitational wave events during LIGO and Virgo's third run, successfully initiating observations for 10 events within 0.5 days, demonstrating potential to constrain electromagnetic emission models.

Contribution

This paper presents a web-based system for rapid sharing of candidate host galaxies and details the follow-up strategy and results during LIGO/Virgo's third observing run.

Findings

Followed up 23 GW events with galaxy-targeted observations.

Initiated observations for 10 events within 0.5 days.

Coverage of up to 9.8% probability area for GW localization.

Abstract

The Laser Interferometer Gravitational-wave Observatory Scientific Collaboration and Virgo Collaboration (LVC) sent out 56 gravitational-wave (GW) notices during the third observing run (O3). Japanese collaboration for Gravitational wave ElectroMagnetic follow-up (J-GEM) performed optical and near-infrared observations to identify and observe an electromagnetic (EM) counterpart. We constructed web-based system which enabled us to obtain and share information of candidate host galaxies for the counterpart, and status of our observations. Candidate host galaxies were selected from the GLADE catalog with a weight based on the three-dimensional GW localization map provided by LVC. We conducted galaxy-targeted and wide-field blind surveys, real-time data analysis, and visual inspection of observed galaxies. We performed galaxy-targeted follow-ups to 23 GW events during O3, and the maximum probability covered by our observations reached to 9.8%. Among them, we successfully started observations for 10 GW events within 0.5 days after the detection. This result demonstrates that our follow-up observation has a potential to constrain EM radiation models for a merger of binary neutron stars at a distance of up to $\sim$100~Mpc with a probability area of $\leq$ 500~deg$^2$.