TY - JOUR
T1 - SPARCS-North Wide-field VLBI Survey: exploring the resolved μJy extra-galactic radio source population with EVN + e-MERLIN
AU - Njeri, Ann
AU - Beswick, Robert J
AU - Radcliffe, Jack F
AU - Thomson, A P
AU - Wrigley, N
AU - Muxlow, T W B
AU - Garrett, M A
AU - Deane, Roger P
AU - Moldon, Javier
AU - Norris, Ray P
AU - Kothes, Roland
N1 - Funding Information:
The authors are grateful to the anonymous reviewer for their insightful and constructive feedback which improved the quality of the final manuscript. Research reported in this publication was supported by a Newton Fund project, DARA (Development in Africa with Radio Astronomy), and awarded by the UK’s Science and Technology Facilities Council (STFC) – grant reference ST/R001103/1. The European VLBI Network is a joint facility of independent European, African, Asian, and North American radio astronomy institutes. Scientific results from data presented in this publication are derived from the following EVN project code: EN004. The research leading to these results has received funding from the European Commission Horizon 2020 Research and Innovation Programme under grant agreement No. 730562 (RadioNet). e-MERLIN and formerly, MERLIN, is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC. We thank the digital infrastructure IRIS www.iris.ac.uk for provision of high-performance computing facilities. STFC IRIS is investing in the UK’s Radio and mm/sub-mm Interferometry Services to improve data quality and throughput. We acknowledge the use of the ilifu cloud computing facility – www.ilifu.ac.za, a partnership between the University of Cape Town, the University of the Western Cape, the University of Stellenbosch, Sol Plaatje University, the Cape Peninsula University of Technology, and the South African Radio Astronomy Observatory. JM acknowledges financial support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), from the grant RTI2018-096228-B-C31 (MICIU/FEDER, EU) and the grant no. IAA4SKA P18-RT-3082 (Regional Government of Andalusia).
Publisher Copyright:
© 2020 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2023/2/1
Y1 - 2023/2/1
N2 - The SKA PAthfinder Radio Continuum Surveys (SPARCS) are providing deep-field imaging of the faint (sub-mJy) extragalactic radio source populations through a series of reference surveys. One of the key science goals for SPARCS is to characterize the relative contribution of radio emission associated with active galactic nucleus (AGN) from star formation (SF) in these faint radio source populations, using a combination of high sensitivity and high angular resolution imaging over a range of spatial scales (arcsec to mas). To isolate AGN contribution from SF, we hypothesize that there exists a brightness temperature cut-off point separating pure AGN from SF. We present a multiresolution (10–100 mas) view of the transition between compact AGN and diffuse SF through a deep wide-field EVN + e-MERLIN, multiple phase centre survey of the centre of the Northern SPARCS (SLOAN) reference field at 1.6 GHz. This is the first (and only) VLBI (+ e-MERLIN) milliarcsecond angular resolution observation of this field, and of the wider SPARCS reference field programme. Using these high spatial resolution (9 pc–0.3 kpc at z ∼ 1.25) data, 11 milliarcsec-scale sources are detected from a targeted sample of 52 known radio sources from previous observations with the e-MERLIN, giving a VLBI detection fraction of ∼21 per cent. At spatial scales of ∼9 pc, these sources show little to no jet structure whilst at ∼0.3 kpc one-sided and two-sided radio jets begin to emerge on the same sources, indicating a possible transition from pure AGN emissions to AGN and SF systems.
AB - The SKA PAthfinder Radio Continuum Surveys (SPARCS) are providing deep-field imaging of the faint (sub-mJy) extragalactic radio source populations through a series of reference surveys. One of the key science goals for SPARCS is to characterize the relative contribution of radio emission associated with active galactic nucleus (AGN) from star formation (SF) in these faint radio source populations, using a combination of high sensitivity and high angular resolution imaging over a range of spatial scales (arcsec to mas). To isolate AGN contribution from SF, we hypothesize that there exists a brightness temperature cut-off point separating pure AGN from SF. We present a multiresolution (10–100 mas) view of the transition between compact AGN and diffuse SF through a deep wide-field EVN + e-MERLIN, multiple phase centre survey of the centre of the Northern SPARCS (SLOAN) reference field at 1.6 GHz. This is the first (and only) VLBI (+ e-MERLIN) milliarcsecond angular resolution observation of this field, and of the wider SPARCS reference field programme. Using these high spatial resolution (9 pc–0.3 kpc at z ∼ 1.25) data, 11 milliarcsec-scale sources are detected from a targeted sample of 52 known radio sources from previous observations with the e-MERLIN, giving a VLBI detection fraction of ∼21 per cent. At spatial scales of ∼9 pc, these sources show little to no jet structure whilst at ∼0.3 kpc one-sided and two-sided radio jets begin to emerge on the same sources, indicating a possible transition from pure AGN emissions to AGN and SF systems.
KW - galaxies: active
KW - galaxies: high-redshift
KW - methods: observational
KW - quasars: supermassive black holes
KW - techniques: high angular resolution
KW - techniques: interferometric
UR - http://www.scopus.com/inward/record.url?scp=85159196670&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/ab459c76-5ee0-30c6-9d3c-8b662784888c/
U2 - 10.1093/mnras/stac3569
DO - 10.1093/mnras/stac3569
M3 - Article
SN - 1365-2966
VL - 519
SP - 1732
EP - 1744
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -