Radio detection of an elusive millisecond pulsar in the Globular Cluster NGC 6397

Abstract

We report the discovery of a new 5.78 ms-period millisecond pulsar (MSP), PSR J1740-5340B (NGC 6397B), in an eclipsing binary system discovered with the Parkes radio telescope (now also known as Murriyang), Australia, and confirmed with the MeerKAT radio telescope in South Africa. The measured orbital period, 1.97 days, is the longest among all eclipsing binaries in globular clusters (GCs) and consistent with that of the coincident X-ray source U18, previously suggested to be a 'hidden MSP'. Our XMM-Newton observations during NGC 6397B's radio quiescent epochs detected no X-ray flares. NGC 6397B is either a transitional MSP or an eclipsing binary in its initial stage of mass transfer after the companion star left the main sequence. The discovery of NGC 6397B potentially reveals a subgroup of extremely faint and heavily obscured binary pulsars, thus providing a plausible explanation to the apparent dearth of binary neutron stars in core-collapsed GCs as well as a critical constraint on the evolution of GCs.

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Cited by in corpus (8)

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• Green Bank Telescope Discovery of the Redback Binary Millisecond Pulsar PSR J0212+5321
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• Exotica in the Globular Cluster M4, Studied with Chandra, HST, and the VLA
• Searching for exotic object companions in the dense core of NGC 362: a multi-wavelength and multi-epoch photometric analysis
• A candidate magnetic helium core white dwarf in the globular cluster NGC 6397
• Exploration of faint X-ray and radio sources in the massive globular cluster M14: A UV-bright counterpart to Nova Ophiuchus 1938