| Abstract |
ABSTRACT We present the first eight months of data from our secondary target programme within the ongoing Dark Energy Spectroscopic Instrument (DESI) survey. Our programme uses a mid-infrared and optical colour selection to preferentially target dust-reddened quasi-stellar objects (QSOs) that would have otherwise been missed by the nominal DESI QSO selection. So far, we have obtained optical spectra for 3038 candidates, of which ∼70 per cent of the high-quality objects (those with robust redshifts) are visually confirmed to be Type 1 QSOs, consistent with the expected fraction from the main DESI QSO survey. By fitting a dust-reddened blue QSO composite to the QSO spectra, we find they are well-fitted by a normal QSO with up to AV ∼ 4 mag of line-of-sight dust extinction. Utilizing radio data from the LOFAR Two-metre Sky Survey (LoTSS) DR2, we identify a striking positive relationship between the amount of line-of-sight dust extinction towards a QSO and the radio detection fraction, that is not driven by radio-loud systems, redshift and/or luminosity effects. This demonstrates an intrinsic connection between dust reddening and the production of radio emission in QSOs, whereby the radio emission is most likely due to low-powered jets or winds/outflows causing shocks in a dusty environment. On the basis of this evidence, we suggest that red QSOs may represent a transitional ‘blow-out’ phase in the evolution of QSOs, where winds and outflows evacuate the dust and gas to reveal an unobscured blue QSO. |
| Authors |
V. A. Fawcett  , D. M. Alexander , A. Brodzeller , Alastair Edge , D. J. Rosario , Adam D. Myers  , J. A. Aguilar , S. P. Ahlen , R. Alfarsy , D. Brooks , Rebecca Canning , C. Circosta , Kyle Dawson , Axel de la Macorra , P. Doel , Kevin Fanning , Andreu Font-Ribera , Jaime E. Forero-Romero , Satya Gontcho A Gontcho , J. Guy , C. M. Harrison , K. Honscheid , S. Juneau , R. Kehoe , T. S. Kisner , Anthony Kremin , Martin Landriau , Marc Manera , Aaron M. Meisner , R. Miquel , John Moustakas , Jundan Nie , Will J. Percival , Claire Poppett , Ragadeepika Pucha , Graziano Rossi , David J. Schlegel , M. Siudek , G. Tarlé , B. A. Weaver , Zhiming Zhou , Hanfa Zou
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