Search for gamma-ray emission from AE Aquarii with seven years of FERMI-LAT observations

TL;DR

This study conducted a seven-year search for gamma-ray emission from AE Aquarii using Fermi-LAT data, but found no significant gamma-ray signals, setting the most restrictive upper limits to date.

Contribution

The paper provides the first deep gamma-ray search for AE Aquarii with extended data and improved ephemeris, establishing new upper limits on gamma-ray flux.

Findings

No gamma-ray pulsations detected at the white dwarf's spin period.

No phase-averaged gamma-ray emission or variability observed.

Set the most restrictive upper limit to gamma-ray flux from AE Aqr.

Abstract

AE Aquarii (AE Aqr) is a cataclysmic binary hosting one of the fastest rotating (P$_{\rm spin}$ = 33.08 s) white dwarfs known. Based on seven years of Fermi Large Area Telescope (LAT) Pass 8 data, we report on a deep search for gamma-ray emission from AE Aqr. Using X-ray observations from ASCA, XMM-Newton, Chandra, Swift, Suzaku, and NuSTAR, spanning 20 years, we substantially extend and improve the spin ephemeris of AE Aqr. Using this ephemeris, we searched for gamma-ray pulsations at the spin period of the white dwarf. No gamma-ray pulsations were detected above 3 $\sigma$ significance. Neither phase-averaged gamma-ray emission nor gamma-ray variability of AE Aquarii is detected by Fermi-LAT. We impose the most restrictive upper limit to the gamma-ray flux from AE Aqr to date: $1.3\times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$ in the 100 MeV-300 GeV energy range, providing constraints on models.