The radio loudness of SDSS quasars from the LOFAR Two-metre Sky Survey: ubiquitous jet activity and constraints on star formation

Macfarlane, C; Best, PN; Sabater, J; Gürkan, G; Jarvis, MJ; Röttgering, HJA; Baldi, RD; Calistro Rivera, G; Duncan, KJ; Morabito, LK; Prandoni, I; Retana-Montenegro, E

Journal article

The radio loudness of SDSS quasars from the LOFAR Two-metre Sky Survey: ubiquitous jet activity and constraints on star formation

Abstract:: We examine the distribution of radio emission from ∼42 000 quasars from the Sloan Digital Sky Survey, as measured in the LOFAR Two-metre Sky Survey (LoTSS). We present a model of the radio luminosity distribution of the quasars that assumes that every quasar displays a superposition of two sources of radio emission: active galactic nuclei (jets) and star formation. Our two-component model provides an excellent match to the observed radio flux density distributions across a wide range of redshifts and quasar optical luminosities; this suggests that the jet-launching mechanism operates in all quasars but with different powering efficiency. The wide distribution of jet powers allows for a smooth transition between the ‘radio-quiet’ and ‘radio-loud’ quasar regimes, without need for any explicit bimodality. The best-fitting model parameters indicate that the star formation rate of quasar host galaxies correlates strongly with quasar luminosity and also increases with redshift at least out to z ∼ 2. For a model where star formation rate scales as Lαbol(1+z)β⁠, we find α = 0.47 ± 0.01 and β = 1.61 ± 0.05, in agreement with far-infrared studies. Quasars contribute ≈0.15 per cent of the cosmic star formation rate density at z = 0.5, rising to 0.4 per cent by z ∼ 2. The typical radio jet power is seen to increase with both increasing optical luminosity and black hole mass independently, but does not vary with redshift, suggesting intrinsic properties govern the production of the radio jets. We discuss the implications of these results for the triggering of quasar activity and the launching of jets.

Publication status:: Published

Peer review status:: Peer reviewed

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APA Style

Macfarlane, C., Best, P. N., Sabater, J., Gürkan, G., Jarvis, M. J., Röttgering, H. J. A., Baldi, R. D., Calistro Rivera, G., Duncan, K. J., Morabito, L. K., Prandoni, I., & Retana-Montenegro, E. (2021). The radio loudness of SDSS quasars from the LOFAR Two-metre Sky Survey: ubiquitous jet activity and constraints on star formation. Monthly Notices of the Royal Astronomical Society, 506(4), 5888–5907.

MLA Style

Macfarlane, C., et al. “The Radio Loudness of SDSS Quasars from the LOFAR Two-Metre Sky Survey: Ubiquitous Jet Activity and Constraints on Star Formation.” Monthly Notices of the Royal Astronomical Society, vol. 506, no. 4, Royal Astronomical Society, 2021, pp. 5888–907.

Chicago Style

Macfarlane, C, PN Best, J Sabater, G Gürkan, MJ Jarvis, HJA Röttgering, RD Baldi, et al. 2021. “The Radio Loudness of SDSS Quasars from the LOFAR Two-Metre Sky Survey: Ubiquitous Jet Activity and Constraints on Star Formation.” Monthly Notices of the Royal Astronomical Society 506 (4): 5888–5907.
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