Does the evolution of the radio luminosity function of star-forming galaxies match that of the star formation rate function?

Bonato, Matteo and Negrello, Mattia and Mancuso, Claudia and De Zotti, Gianfranco and Ciliegi, Paolo and Cai, Zhen-Yi and Lapi, Andrea and Massardi, Marcella and Bonaldi, Anna and Sajina, Anna and Smolčić, Vernesa and Schinnerer, Eva (2017) Does the evolution of the radio luminosity function of star-forming galaxies match that of the star formation rate function?. Monthly Notices of the Royal Astronomical Society, 469. pp. 1912-1923. ISSN 0035-8711

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Abstract

The assessment of the relationship between radio continuum luminosity and star formation rate (SFR) is of crucial importance to make reliable predictions for the forthcoming ultra-deep radio surveys and to allow a full exploitation of their results to measure the cosmic star formation history. We have addressed this issue by matching recent accurate determinations of the SFR function up to high redshifts with literature estimates of the 1.4 GHz luminosity functions of star-forming galaxies (SFGs). This was done considering two options, proposed in the literature, for the relationship between the synchrotron emission (Lsynch), that dominates at 1.4 GHz, and the SFR: a linear relation with a decline of the Lsynch/SFR ratio at low luminosities or a mildly non-linear relation at all luminosities. In both cases, we get good agreement with the observed radio luminosity functions but, in the non-linear case, the deviation from linearity must be small. The luminosity function data are consistent with a moderate increase of the Lsynch/SFR ratio with increasing redshift, indicated by other data sets, although a constant ratio cannot be ruled out. A stronger indication of such increase is provided by recent deep 1.4-GHz counts, down to μJy levels. This is in contradiction with models predicting a decrease of that ratio due to inverse Compton cooling of relativistic electrons at high redshifts. Synchrotron losses appear to dominate up to z ≃ 5. We have also updated the Massardi et al. evolutionary model for radio loud AGNs.

Item Type: Article
Keywords: galaxies, active – galaxies, evolution – radio continuum, galaxies
Date: 2017
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.
Divisions: Faculty of Science > Department of Physics
Publisher: Oxford University Press
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 08 Nov 2017 10:38
Last Modified: 20 Nov 2017 10:14
URI: http://digre.pmf.unizg.hr/id/eprint/5675

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