Large Binocular Telescope observations of PSR J2043+2740

TL;DR

This study used the Large Binocular Telescope to perform deep optical imaging of the old gamma-ray pulsar PSR J2043+2740, setting the deepest optical emission limit and discussing its implications on pulsar emission models.

Contribution

First deep optical imaging of PSR J2043+2740 with LBT, providing the most stringent optical emission limit for this pulsar.

Findings

No optical counterpart detected down to V~26.6 magnitude.

Detected nearby object unrelated to the pulsar.

Results constrain pulsar emission models.

Abstract

We present the results of deep optical imaging of the radio/$\gamma$-ray pulsar PSR J2043+2740, obtained with the Large Binocular Telescope (LBT). With a characteristic age of 1.2 Myr, PSR J2043+2740 is one of the oldest (non recycled) pulsars detected in $\gamma$-rays, although with still a quite high rotational energy reservoir ($\dot{E}_{\rm rot} = 5.6 \times 10^{34}$ erg s$^{-1}$). The presumably close distance (a few hundred pc), suggested by the hydrogen column density ($N_{\rm H} \lesssim 3.6 \times 10^{20}$ cm$^{-2}$), would make it a viable target for deep optical observations, never attempted until now. We observed the pulsar with the Large Binocular Camera of the LBT. The only object (V=25.44$\pm$0.05) detected within ~3" from the pulsar radio coordinates is unrelated to it. PSR J2043+2740 is, thus, undetected down to V~26.6 (3-$\sigma$), the deepest limit on its optical emission. We discuss the implications of this result on the pulsar emission properties.