Speaker
Description
MAXI scans about 85% of the whole sky in its orbital period (92 min) by sweeping the sky with a slit-shaped field-of-view (FOV). It can cover a large localized area of a GW event detected by GW detectors and search for an emission from the area before the time of the GW trigger. From the start of LIGO’s operation, MAXI has searched for X-ray counterparts of GW events and reported on upper limits of X-ray flux in the localized areas starting with GW 150914. In GW 170817, MAXI did not observe GW 170817 at the trigger time because during the high-voltage-off operation. The first observation of the position of GW 170817 was eventually performed 4.6 hours after the trigger, though it was the earliest X-ray observation of the EM counterpart of GW 170817. From LIGO’s Observing Runs 3, we performed the operation carefully expanding HV-on area so that all-sky coverage is achieved. In O4, we have been reporting to GCN the observations of the GW events that satisfied the criteria of False Alert Rate smaller than 20 per year and probability of neutron star merger larger than 5%. We report the observations and the operations for GW EM counterparts by MAXI.
