@article{58d8a91fabd14e4b92161d42d03ac069,
title = "Exploring the radio-loudness of SDSS quasars with spectral stacking",
abstract = "We use new 144 MHz observations over 5634 deg2 from the LOFAR (Low Frequency Array) Two-metre Sky Survey (LoTSS) to compile the largest sample of uniformly selected, spectroscopically confirmed quasars from the 14th data release of the Sloan Digital Sky Survey (SDSS-DR14). Using the classical definition of radio loudness, R = log (L1.4GHz/Li), we identify 3697 radio-loud (RL) and 111 132 radio-quiet (RQ) sources at 0.6 < z < 3.4. To study their properties, we develop a new rest-frame spectral stacking algorithm, designed with forthcoming massively multiplexed spectroscopic surveys in mind, and use it to create high signal-to-noise composite spectra of each class, matched in redshift and absolute i-band magnitude. We show that RL quasars have redder continuum and enhanced [O ii] emission than their RQ counterparts. These results persist when additionally matching in black hole mass, suggesting that this parameter is not the defining factor in making a quasi-stellar object (QSO) RL. We find that these features are not gradually varying as a function of radio loudness, but are maintained even when probing deeper into the RQ population, indicating that a clear-cut division in radio loudness is not apparent. Upon examining the star formation rates (SFRs) inferred from the [O ii] emission line, with the contribution from active galactic nucleus removed using the [Ne v] line, we find that RL quasars have a significant excess of star formation relative to RQ quasars out to z = 1.9 at least. Given our findings, we suggest that RL sources either preferably reside in gas-rich systems with rapidly spinning black holes, or represent an earlier obscured phase of QSO evolution.",
keywords = "techniques: spectroscopic, galaxies: active, quasars: general, radio continuum; galaxies",
author = "Arnaudova, {M. I.} and Smith, {D. J. B.} and Hardcastle, {M. J.} and S. Das and A. Drake and K. Duncan and G. G{\"u}rkan and M. Magliocchetti and Morabito, {L. K.} and Petley, {J. W.} and S. Shenoy and C. Tasse",
note = "22 pages, 17 figures, accepted for publication in MNRAS Funding Information: We thank the anonymous referee for the helpful comments that have improved the manuscript. MIA acknowledges support from the UK Science and Technology Facilities Council (STFC) studentship under the grant ST/V506709/1. DJBS, MJH, and ABD acknowledge support from the STFC under the grant ST/V000624/1. KJD acknowledges support from the STFC through an Ernest Rutherford Fellowship (grant no. ST/W003120/1). LKM is grateful for support from the Medical Research Council (MR/T042842/1). SD acknowledges support from the STFC via studentship grant no. ST/W507490/1. SS acknowledges support from the STFC via studentship grant no. ST/X508408/1. LOFAR is the Low Frequency Array designed and constructed by ASTRON. It has observing, data processing, and data storage facilities in several countries, which are owned by various parties (each with their own funding sources), and that are collectively operated by the ILT foundation under a joint scientific policy. The ILT resources have benefitted from the following recent major funding sources: CNRS-INSU, Observatoire de Paris and Universit{\'e} d{\textquoteright}Orl{\'e}ans, France; BMBF, MIWFNRW, MPG, Germany; Science Foundation Ireland (SFI), Department of Business, Enterprise and Innovation (DBEI), Ireland; NWO, The Netherlands; The Science and Technology Facilities Council, UK; Ministry of Science and Higher Education, Poland; The Istituto Nazionale di Astrofisica (INAF), Italy. This research made use of the Dutch national e-infrastructure with support of the SURF Cooperative (e-infra 180169) and the LOFAR e-infra group. The J{\"u}lich LOFAR Long Term Archive and the German LOFAR network are both coordinated and operated by the J{\"u}lich Supercomputing Centre (JSC), and computing resources on the supercomputer JUWELS at JSC were provided by the Gauss Centre for Supercomputing e.V. (grant CHTB00) through the John von Neumann Institute for Computing (NIC). This research made use of the University of Hertfordshire high performance computing facility and the LOFAR-UK computing facility located at the University of Hertfordshire and supported by STFC [ST/V002414/1], and of the Italian LOFAR IT computing infrastructure supported and operated by INAF, and by the Physics Department of Turin University (under an agreement with Consorzio Interuniversitario per la Fisica Spaziale) at the C3S Supercomputing Centre, Italy. Publisher Copyright: {\textcopyright} 2024 The Author(s).",
year = "2024",
month = mar,
day = "1",
doi = "10.1093/mnras/stae233",
language = "English",
volume = "528",
pages = "4547--4567",
journal = "Monthly Notices of the Royal Astronomical Society ",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "3",
}