# Fermi observations of the LIGO event GW170104

## TL;DR

This paper reports on Fermi satellite observations of the GW170104 black hole merger event, finding no electromagnetic counterparts and providing flux upper bounds, while also improving analysis techniques for future gravitational wave events.

## Contribution

The study presents the first detailed gamma-ray analysis of GW170104 and introduces improved pipelines for detecting electromagnetic counterparts to gravitational wave events.

## Key findings

- No electromagnetic counterpart detected for GW170104.
- Established flux upper bounds in gamma-ray ranges.
- Enhanced analysis pipelines for future GW events.

## Abstract

We present the \emph{Fermi} Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) observations of the LIGO binary black hole merger (BBH) event GW170104. No candidate electromagnetic counterparts was detected by either GBM or LAT. A detailed analysis of the GBM and LAT data over timescales from seconds to days covering the LIGO localization region is presented. The resulting flux upper bound from the GBM is (5.2--9.4)$\times$10$^{-7}$ erg cm$^{-2}$ s$^{-1}$ in the 10-1000 keV range and from the LAT is (0.2--13)$\times$10$^{-9}$ erg cm$^{-2}$ s$^{-1}$ in the 0.1--1 GeV range. We also describe the improvements to our automated pipelines and analysis techniques for searching for and characterizing the potential electromagnetic counterparts for future gravitational wave events from Advanced LIGO/VIRGO.