Fermi-LAT Search for Pulsar Wind Nebulae around gamma-ray Pulsars

TL;DR

This study uses Fermi-LAT data to search for pulsar wind nebulae around gamma-ray pulsars, identifying new candidates and providing constraints on their emission properties across multiple energy bands.

Contribution

It presents the first systematic search for PWNe in the off-pulse gamma-ray emission of 54 pulsars using 16 months of Fermi-LAT data, discovering new nebula candidates and setting upper limits.

Findings

Detected significant off-pulse emission in 10 sources.

Identified a new PWN candidate associated with PSR J1023-5746.

Provided flux upper limits for 44 pulsars, constraining PWN models.

Abstract

The high sensitivity of the Fermi-LAT (Large Area Telescope) offers the first opportunity to study faint and extended GeV sources such as pulsar wind nebulae (PWNe). After one year of observation the LAT detected and identified three pulsar wind nebulae: the Crab Nebula, Vela-X and the PWN inside MSH 15-52. In the meantime, the list of LAT detected pulsars increased steadily. These pulsars are characterized by high energy loss rates from ~3 \times 10^{33} erg s$^{-1}$ to 5 \times 10$^{38}$ erg s$^{-1}$ and are therefore likely to power a PWN. This paper summarizes the search for PWNe in the off-pulse windows of 54 LAT-detected pulsars using 16 months of survey observations. Ten sources show significant emission, seven of these likely being of magnetospheric origin. The detection of significant emission in the off-pulse interval offers new constraints on the gamma-ray emitting regions in pulsar magnetospheres. The three other sources with significant emission are the Crab Nebula, Vela-X and a new pulsar wind nebula candidate associated with the LAT pulsar PSR J1023-5746, coincident with the TeV source HESS J1023-575. We further explore the association between the H.E.S.S. and the Fermi source by modeling its spectral energy distribution. Flux upper limits derived for the 44 remaining sources are used to provide new constraints on famous PWNe that have been detected at keV and/or TeV energies.