The e-MERLIN Galaxy Evolution Survey (e-MERGE): overview and survey description

T. W. B. Muxlow, A. P. Thomson, J. F. Radcliffe, N. H. Wrigley, R. J. Beswick, Ian Smail, I. M. McHardy, S. T. Garrington, R. J. Ivison, M. J. Jarvis, I. Prandoni, M. Bondi, D. Guidetti, M. K. Argo, David Bacon, P. N. Best, A. D. Biggs, S. C. Chapman, K. Coppin, T. K. GarrattM. A. Garrett, E. Ibar, Jean-Paul Kneib, Kirsten K. Knudsen, L. V. E. Koopmans, L. K. Morabito, E. J. Murphy, A. Njeri, Chris Pearson, M. A. Perez-Torres, A. M. S. Richards, H. J. A. Rottgering, M. T. Sargent, Stephen Serjeant, C. Simpson, J. M. Simpson, A. M. Swinbank, E. Varenius, T. Venturi

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We present an overview and description of the e-MERGE Survey (e-MERLIN Galaxy Evolution Survey) Data Release 1 (DR1), a large program of high-resolution 1.5-GHz radio observations of the GOODS-N field comprising ∼140 h of observations with enhanced-Multi-Element Remotely Linked Interferometer Network (e-MERLIN) and ∼40 h with the Very Large Array (VLA). We combine the long baselines of e-MERLIN (providing high angular resolution) with the relatively closely packed antennas of the VLA (providing excellent surface brightness sensitivity) to produce a deep 1.5-GHz radio survey with the sensitivity (⁠∼1.5μ Jy beam−1), angular resolution (0.2–0.7 arcsec) and field-of-view (∼15 × 15 arcmin2) to detect and spatially resolve star-forming galaxies and active galactic nucleus (AGN) at z ≳ 1. The goal of e-MERGE is to provide new constraints on the deep, sub-arcsecond radio sky which will be surveyed by SKA1-mid. In this initial publication, we discuss our data analysis techniques, including steps taken to model in-beam source variability over an ∼20-yr baseline and the development of new point spread function/primary beam models to seamlessly merge e-MERLIN and VLA data in the uv plane. We present early science results, including measurements of the luminosities and/or linear sizes of ∼500 galaxies selected at 1.5 GHz. In combination with deep Hubble Space Telescope observations, we measure a mean radio-to-optical size ratio of re-MERGE/rHST ∼ 1.02 ± 0.03, suggesting that in most high-redshift galaxies, the ∼GHz continuum emission traces the stellar light seen in optical imaging. This is the first in a series of papers that will explore the ∼kpc-scale radio properties of star-forming galaxies and AGN in the GOODS-N field observed by e-MERGE DR1.
Original languageEnglish
Pages (from-to)1188-1208
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Early online date8 May 2020
Publication statusPublished - 1 Jun 2020


  • RCUK
  • STFC
  • ST/P000649/1


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