The MAVERIC Survey: The first radio and X-ray limits on the detached black holes in NGC 3201

TL;DR

This study uses radio and X-ray observations from the MAVERIC survey to set the first limits on accretion activity of confirmed black holes in NGC 3201, revealing extremely low accretion efficiencies and expanding multiwavelength source catalogs.

Contribution

It provides the first radio and X-ray limits on black holes in NGC 3201 and integrates multiwavelength data to analyze cluster sources and populations.

Findings

No radio or X-ray detection of the black holes, indicating very low accretion rates.

Constraints on accretion efficiency, with radiative efficiency ≤ 1.5×10⁻⁵ for one system.

Identification of a new red straggler with X-ray emission and analysis of sub-subgiant populations.

Abstract

The Galactic globular cluster NGC 3201 is the first Galactic globular cluster observed to host dynamically-confirmed stellar-mass black holes, containing two confirmed and one candidate black hole. This result indicates that globular clusters can retain black holes, which has important implications for globular cluster evolution. NGC 3201 has been observed as part of the MAVERIC survey of Galactic globular clusters. We use these data to confirm that there is no radio or X-ray detection of the three black holes, and present the first radio and X-ray limits on these sources. These limits indicate that any accretion present is at an extremely low rate and may be extremely inefficient. In particular, for the system ACS ID #21859, by assuming the system is tidally locked and any accretion is through the capture of the companion's winds, we constrain the radiative efficiency of any accretion to $\leq1.5\times10^{-5}$. We also combine the radio and X-ray source catalogues from the MAVERIC survey with the existing MUSE spectroscopic surveys and the HUGS catalogue of NGC 3201 to provide a catalogue of 42 multiwavelength sources in this cluster. We identify a new red straggler source with X-ray emission, and investigate the multiwavelength properties of the sub-subgiant population in the cluster.