The MAVERIC Survey: Radio catalogs and source counts from deep Very Large Array imaging of 25 Galactic globular clusters

Abstract

The MAVERIC survey is the first deep radio continuum imaging survey of Milky Way globular clusters, with a central goal of finding and classifying accreting compact binaries, including stellar-mass black holes. Here we present radio source catalogs for 25 clusters with ultra-deep Karl G. Jansky Very Large Array observations. The median observing time was 10 hr per cluster, resulting in typical rms sensitivities of 2.3 and 2.1 uJy per beam at central frequencies of 5.0 and 7.2 GHz, respectively. We detect nearly 1300 sources in our survey at 5 sigma, and while many of these are likely to be background sources, we also find strong evidence for an excess of radio sources in some clusters. The radio spectral index distribution of sources in the cluster cores differs from the background, and shows a bimodal distribution. We tentatively classify the steep-spectrum sources (those much brighter at 5.0 GHz) as millisecond pulsars and the flat-spectrum sources as compact or other kinds of binaries. These provisional classifications will be solidified with the future addition of X-ray and optical data. The outer regions of our images represent a deep, relatively wide field (~ 0.4/sq. deg) and high resolution C band background survey, and we present source counts calculated for this area. We also release radio continuum images for these 25 clusters to the community.

published in ApJ. table 3 available as an ancillary CSV file. pending final hosting by the NRAO archive, the FITS images may be found at: https://www.dropbox.com/sh/a7a9qsqrepq5fmb/AABTtfMkftMSTUEFjzw6NU6Xa

References in corpus (13)

• The NumPy array: a structure for efficient numerical computation
• The Dynamical Evolution of Stellar Black Holes in Globular Clusters
• A radio pulsing white dwarf binary star
• Black holes and core expansion in massive star clusters
• A new method to separate star forming from AGN galaxies at intermediate redshift: The submillijansky radio population in the VLA-COSMOS survey
• The radio/X-ray domain of black hole X-ray binaries at the lowest radio luminosities
• A 1.4-GHz Arecibo Survey for Pulsars in Globular Clusters
• Disk-jet coupling in low-luminosity accreting neutron stars
• Very Broad [O III]4959,5007 Emission from the NGC 4472 Globular Cluster RZ2109 and Implications for the Mass of Its Black Hole X-ray Source
• Six New Recycled Globular Cluster Pulsars Discovered with the Green Bank Telescope
• Precision astrometry of pulsars and other compact radio sources in the globular cluster M15
• The ATLAS 9.0 GHz Survey of the Extended Chandra Deep Field South: The Faint 9.0 GHz Radio Population
• Sub-millimetre source identifications and the micro-Jansky source population at 8.4 GHz in the William Herschel Deep Field

Cited by in corpus (4)

• The evolving radio jet from the neutron star X-ray binary 4U 1820$-$30
• The MAVERIC Survey: Simultaneous Chandra and VLA observations of the transitional millisecond pulsar candidate NGC 6652B
• The MAVERIC survey: A catalogue of radio sources in southern globular clusters from the Australia Telescope Compact Array
• The MAVERIC Survey: The first radio and X-ray limits on the detached black holes in NGC 3201