Discovery of two new millisecond pulsars towards the Galactic bulge

TL;DR

This paper reports the discovery of two new millisecond pulsars near the Galactic center, supporting the hypothesis that such pulsars could explain the gamma-ray excess observed in the Galactic bulge.

Contribution

It introduces a novel candidate selection method and reports the first deep radio pulsation searches leading to the discovery of two MSPs in the Galactic bulge.

Findings

Discovered two new millisecond pulsars near the Galactic center.

Doubled the known MSP population within 2 degrees of the Galactic center.

Identified a black widow candidate among the new pulsars.

Abstract

The mysterious Galactic Center Excess of gamma rays could be explained by a large population of millisecond pulsars hiding in the Galactic bulge, too faint to be detected as individual high-energy point sources by the Fermi Large Area Telescope, as well as too fast and too dispersed to be detected in shallow radio pulsation surveys. Motivated by an innovative candidate selection method, we aim at detecting millisecond pulsars associated with the Galactic Center Excess by carrying deep radio pulsation searches towards promising candidates detected in the inner Galaxy, in X rays by Chandra, and in radio or gamma rays by the Very Large Array or Fermi. We conducted deep radio observation and follow-up campaigns with MeerKAT, the Murriyang and the Green Bank telescopes towards 9 X-ray candidate sources. We here report the detection of two new millisecond pulsars, including a black widow candidate, towards the Galactic bulge: PSRs J1740-2805 and J1740-28. These discoveries double the number of MSPs discovered within the innermost 2 degree from the Galactic center.