2-6 September 2024
CJD Bonn Castell
Europe/Berlin timezone
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Contribution

CJD Bonn Castell

The Synoptic Wide-field EVN–eMERLIN commensal Pilot Survey (SWEEPS) - Overview and Results

Speakers

  • Célestin HERBÉ-GEORGE

Primary authors

Co-authors

Content

The high angular resolution and sensitivity of VLBI offers a unique tool to identify and study AGN and star-formation activity over cosmic time. VLBI observations are crucial for identifying young radio sources and unveiling older restarted radio sources. Also, radio imaging over a large range of angular scales is needed to determine the role of black hole feedback and jet-induced star formation in galaxies. To answer these questions and to find rare radio sources, such as gravitational lenses and binary/dual AGN, all-sky VLBI surveys are needed. Despite recent technical advances, such as multiple phase centre correlation and multi-source self-calibration, only a limited part of the sky has been observed within a few well-studied fields. To enter the realm of large statistical studies, a significantly larger area of sky must be observed, which would limit the VLBI available time for other single-target science projects.

SWEEPS (Synoptic Wide-field EVN–eMERLIN commensal Pilot Survey) is a pilot for a potential future commensal survey mode for the EVN+e-MERLIN, where single-target PI-led observations are re-correlated at the position of all known radio sources within 12 arcmin. Initially, the phase centres are selected using the LoTSS survey program of LOFAR, in the future however, additional phase centres will be provided by a wide-field image using the short baselines of e-MERLIN that will be generated on-the-fly the initial correlation. Full implementation of this program has the potential to observe up to ~9000 radio sources per year, yielding an expected 1900 VLBI detections without any additional observing time. Here, we present results and methods from the pilot program, where we selected and processed 257 additional phase centres using a PI-led single target observation. In this study, we combined our high resolution data with LOFAR, FIRST and VLASS to characterise our detections. Along the way, we investigated imaging methods for the multiple angular-scales of e-MERLIN + EVN and have tested robust pipelines to accurately detect sources.