X-ray upper limits of GW150914 with MAXI

TL;DR

This study used MAXI to search for X-ray signals from GW150914, setting upper limits on X-ray emission and demonstrating MAXI's capability to detect such signals if associated with short GRBs.

Contribution

First to set X-ray upper limits for GW150914 using MAXI, demonstrating its ability to detect X-ray emissions from GW events similar to short GRBs.

Findings

No significant X-ray variations detected in GW150914 region.

Established 3σ upper limits for X-ray emission in 2-20 keV band.

MAXI can detect X-ray emissions if GW events are linked to short GRBs.

Abstract

We searched for X-ray candidates of the gravitational wave (GW) event GW150914 with Monitor of All-sky X-ray Image (MAXI). MAXI observed the error region of the GW event GW150914 from 4 minutes after the event and covered about 90% of the error region in 25 minutes. No significant time variations on timescales of 1 s to 4 days were found in the GW error region. The $3\sigma$ upper limits for the X-ray emission associated with the GW event in 2--20 keV were 9.5 $\times 10^{-10}$, 2.3 $\times 10^{-10}$, and 0.8 $\times 10^{-10}$ ergs cm$^{-2}$ s$^{-1}$ for the time scale of $\sim$ 1000 s, 1 day, and 10 days, respectively. If GW events are associated with short GRBs like GRB 050709, MAXI will be able to detect X-ray emissions from the source.