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Connecting radio emission to AGN wind properties with Broad Absorption Line Quasars

Petley, J W and Morabito, L K and Alexander, D M and Rankine, A L and Fawcett, V A and Rosario, D J and Matthews, J H and Shimwell, T M and Drabent, A (2022) 'Connecting radio emission to AGN wind properties with Broad Absorption Line Quasars.', Monthly Notices of the Royal Astronomical Society., 515 (4). pp. 5159-5174.


Broad Absorption Line Quasars (BALQSOs) show strong signatures of powerful outflows, with the potential to alter the cosmic history of their host galaxies. These signatures are only seen in ∼10% of optically selected quasars, although the fraction significantly increases in IR and radio selected samples. A proven physical explanation for this observed fraction has yet to be found, along with a determination of why this fraction increases at radio wavelengths. We present the largest sample of radio matched BALQSOs using the LOFAR Two-metre Sky Survey Data Release 2 and employ it to investigate radio properties of BALQSOs. Within the DR2 footprint, there are 3537 BALQSOs from Sloan Digital Sky Survey DR12 with continuum signal to noise ≥5. We find radio-detections for 1108 BALQSOs, with an important sub-population of 120 LoBALs, an unprecedented sample size for radio matched BALQSOs given the sky coverage to date. BALQSOs are a radio-quiet population that show an increase of × 1.50 radio-detection fraction compared to non-BALQSOs. LoBALs show an increase of × 2.22 that of non-BALQSO quasars. We show that this detection fraction correlates with wind-strength, reddening and C IV emission properties of BALQSOs and that these features may be connected, although no single property can fully explain the enhanced radio detection fraction. We create composite spectra for sub-classes of BALQSOs based on wind strength and colour, finding differences in the absorption profiles of radio-detected and radio-undetected sources, particularly for LoBALs. Overall, we favour a wind-ISM interaction explanation for the increased radio-detection fraction of BALQSOs.

Item Type:Article
Full text:(AM) Accepted Manuscript
Available under License - Creative Commons Attribution 4.0.
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Full text:(VoR) Version of Record
Available under License - Creative Commons Attribution 4.0.
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Publisher statement:© The Author(s) 2022. Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Date accepted:15 July 2022
Date deposited:15 August 2022
Date of first online publication:23 July 2022
Date first made open access:15 August 2022

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