The MAVERIC Survey: New compact binaries revealed by deep radio continuum observations of the Galactic globular cluster Terzan 5

Abstract

Owing to its massive, dense core, Terzan 5 has the richest population of millisecond pulsars known among Galactic globular clusters. Here we report new deep $2-8$GHz radio continuum observations of Terzan\,5 obtained with the Karl G. Jansky Very Large Array. We have identified a total of 24 sources within the cluster half-light radius, including 17 within the core radius. 19 are associated with previously studied millisecond pulsars and X-ray binaries. Three of the new radio sources have steep radio spectra and are located within the cluster core, as expected for millisecond pulsars. These three sources have hard X-ray photon indices ($\Gamma =1.3-1.5$) and highly variable X-ray emission, suggesting they are binary millisecond pulsars belonging to the spider class. For the most X-ray luminous of these sources, the redback spider classification is confirmed by its X-ray light curve, which shows an orbital period of 12.32 hr and double peaked structure around X-ray maximum. The likely discovery of bright binary millisecond pulsars in a well-studied cluster like Terzan 5 highlights how deep radio continuum imaging can complement pulsar search and timing observations in finding probable eclipsing systems. The other new radio source in the core has a flat radio spectrum and is X-ray faint ($L_X\approx 2\times 10^{31}$ erg s${}^{-1}$) with a photon index $\Gamma =2.1\pm 0.5$, consistent with the properties expected for a quiescent stellar-mass black hole X-ray binary.

19 pages, 12 figures, 3 tables. Accepted for publication in ApJ

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Cited by in corpus (12)

• Stellar structures, molecular gas, and star formation across the PHANGS sample of nearby galaxies
• The observed mass distribution of Galactic black hole LMXBs is biased against massive black holes
• Discovery and timing of ten new millisecond pulsars in the globular cluster Terzan 5
• Constraints on the Cosmological Coupling of Black Holes from the Globular Cluster NGC 3201
• A Deep Chandra X-ray Observatory Study of the Millisecond Pulsar Population in the Globular Cluster Terzan 5
• Upgraded GMRT survey for pulsars in globular clusters. I: Discovery of a millisecond binary pulsar in NGC 6652
• A Deep Search for Faint Chandra X-ray Sources, Radio Sources, and Optical Counterparts in NGC 6752
• The MAVERIC survey: A catalogue of radio sources in southern globular clusters from the Australia Telescope Compact Array
• A 34 Yr Timing Solution of the Redback Millisecond Pulsar Terzan 5A
• The flickering radio jet from the quiescent black hole X-ray binary A0620-00
• Mining the time axis with TRON. I. Millisecond pulsars in Omega Centauri, Terzan 5 and 47 Tucanae detected through MeerKAT interferometric imaging
• Digging deeper into the dense Galactic globular cluster Terzan 5 with Electron-Multiplying CCDs. Variable star detection and new discoveries