VLT observations of the solitary millisecond pulsar PSR J 2124 − 3358 Roberto

About 100 millisecond (ms) pulsars have been identified in the Galaxy, and only ≈ 10% of them are solitary, i.e. without a binary companion. Nothing is known on the optical emission properties of millisecond pulsars. Observations of solitary millisecond pulsars are the only way to detect their faint optical radiation, otherwise buried by the brighter white dwarf companion. As in the case of solitary, non millisecond pulsars, an X-ray detection represents the first step for a follow-up identification campaign in the optical. Among the X-ray detected millisecond pulsars, PSR J2124−3358 stands out as an ideal case because it is very close (≤ 270 pc) and little absorbed. Here, we report on recent VLT observations of the PSR J2124−3358 aimed at the identification of its optical counterpart. No optical emission from the pulsar has been detected down to a limiting flux of V ∼ 27.8.