A VLITE Search for Millisecond Pulsars in Globular Clusters: Discovery of a Pulsar in GLIMPSE-C01

Abstract

We present results from a search for pulsars in globular clusters, including the discovery of a new millisecond pulsar in the stellar cluster GLIMPSE-C01. We searched for low frequency radio sources within 97 globular clusters using images from the VLA Low-band Ionosphere and Transient Experiment (VLITE) and epochs 1 and 2 of the VLITE Commensal Sky Survey (VCSS). We discovered 10 sources in our search area, four more than expected from extragalactic source counts at our sensitivity limits. The strongest pulsar candidate was a point source found in GLIMPSE-C01 with a spectral index ~ -2.6, and we present additional measurements at 0.675 and 1.25 GHz from the GMRT and 1.52 GHz from the VLA which confirm the spectral index. Using archival Green Bank Telescope S-band data from 2005, we detect a binary pulsar with a spin period of 19.78 ms within the cluster. Although we cannot confirm that this pulsar is at the same position as the steep spectrum source using the existing data, the pulse flux is consistent with the predicted flux density from other frequencies, making it a probable match. The source also shows strong X-ray emission, indicative of a higher magnetic field than most millisecond pulsars, suggesting that its recycling was interrupted. We demonstrate that low frequency searches for steep spectrum sources are an effective way to identify pulsar candidates, particularly on sightlines with high dispersion.

19 pages, 4 figures, submitted to Astrophysical Journal

References in corpus (11)

• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• A Quick Look at the $3$GHz Radio Sky I. Source Statistics from the Very Large Array Sky Survey
• The Rapid ASKAP Continuum Survey Paper II: First Stokes I Source Catalogue Data Release
• Chandra X-Ray Observations of Nineteen Millisecond Pulsars in the Globular Cluster 47 Tucanae
• New pulsar rotation measures and the Galactic magnetic field
• Eight new millisecond pulsars from the first MeerKAT globular cluster census
• Upgraded GMRT survey for pulsars in globular clusters. I: Discovery of a millisecond binary pulsar in NGC 6652
• MAXI J1848-015: The First Detection of Relativistically Moving Outflows from a Globular Cluster X-ray Binary
• A 2 day orbital period for a redback millisecond pulsar candidate in the globular cluster NGC 6397
• A blazar candidate for the Fermi source 4FGL J1848.7-0129