The MAVERIC Survey: Still No Evidence for Accreting Intermediate-mass Black Holes in Globular Clusters

TL;DR

This comprehensive radio survey of 50 globular clusters found no evidence of intermediate-mass black holes, suggesting such black holes are rare or absent in these environments.

Contribution

The study provides the deepest radio continuum observations to date, setting stringent upper limits on the presence of intermediate-mass black holes in globular clusters.

Findings

No detections of accreting intermediate-mass black holes in any cluster.

Stacked data also show no evidence for such black holes.

Results imply intermediate-mass black holes are rare or absent in globular clusters.

Abstract

We present the results of an ultra-deep, comprehensive radio continuum survey for the accretion signatures of intermediate-mass black holes in globular clusters. The sample, imaged with the Karl G.~Jansky Very Large Array and the Australia Telescope Compact Array, comprises 50 Galactic globular clusters. No compelling evidence for an intermediate-mass black hole is found in any cluster in our sample. In order to achieve the highest sensitivity to low-level emission, we also present the results of an overall stack of our sample, as well as various subsamples, also finding non-detections. These results strengthen the idea that intermediate-mass black holes with masses $\gtrsim 1000 M_{\odot}$ are rare or absent in globular clusters.