VLT observations of Fermi pulsars

TL;DR

This study used the VLT to perform deep optical observations of two Fermi-detected pulsars, setting upper limits on their optical luminosity and efficiency, which are lower than the Crab pulsar and align with their ages.

Contribution

First deep optical observations of PSR J1357-6429 and PSR J1048-5832 with VLT, providing upper limits on their optical emission and efficiency.

Findings

No optical detection down to V~27 and V~27.6.

Optical efficiency lower than Crab pulsar.

Results consistent with pulsar ages.

Abstract

Many energetic gamma-ray pulsars discovered by Fermi are promising candidates for optical follow-ups. We present the results of the first deep optical observations of the two Vela-like Fermi pulsars PSR J1357-6429 and PSR J1048-5832 performed with the VLT. However, they have not been detected down to V~27 and V~27.6, respectively (3 sigma). These upper limits suggest an efficiency in converting spin-down power into optical luminosity < 7x10d-7 and <6x10d-6, respectively, lower than the Crab pulsar and, possibly, more compatible with the spin-down age of these two pulsars.