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Faraday tomography of a field centred on the extragalactic point source 3C 196 with the LOw Frequency ARray (LOFAR) revealed an intertwined structure of diffuse polarised emission with straight depolarisation canals and tracers of the magnetized and multi-phase interstellar medium (ISM), such as dust and line emission from atomic hydrogen (HI). This study aims at extending the multi-tracer analysis of LOFAR data to three additional fields in the surroundings of the 3C 196 field. For the first time, we study the three-dimensional structure of the LOFAR emission by determining the distance to the depolarisation canals. We use the Rolling Hough Transform to compare the orientation of the depolarisation canals with that of the filamentary structure seen in HI and, based on starlight and dust polarisation data, with that of the plane-of-the-sky magnetic field. Stellar parallaxes from $Gaia$ complement the starlight polarisation with the corresponding distances. Faraday tomography of the three fields shows a rich network of diffuse polarised emission at Faraday depths between $-10~{\rm rad~m^{-2}}$ and $+15~{\rm rad~m^{-2}}$. A complex system of straight depolarisation canals resembles that of the 3C 196 field. The depolarisation canals align both with the HI filaments and with the magnetic field probed by dust. The observed alignment suggests that an ordered magnetic field organises the multiphase ISM over a large area ($\sim$20$^{\circ}$). In one field, two groups of stars at distances below and above 200 pc, respectively, show distinct magnetic-field orientations. These are both comparable with the orientations of the depolarisation canals in the same field. We conclude that the depolarisation canals likely trace the same change of the magnetic field as probed by the stars, which corresponds to the edge of the Local Bubble., Comment: 14 pages, 11 figures, accepted for publication in A&A

Mapping the average AGN luminosity across galaxy populations and over time encapsulates important clues on the interplay between supermassive black hole (SMBH) and galaxy growth. This paper presents the demography, mean power and cosmic evolution of radio AGN across star-forming galaxies (SFGs) of different stellar masses (${M_{*}}$). We exploit deep VLA-COSMOS 3 GHz data to build the rest-frame 1.4 GHz AGN luminosity functions at 0.1$\leq$$z$$\leq$4.5 hosted in SFGs. Splitting the AGN luminosity function into different ${M_{*}}$ bins reveals that, at all redshifts, radio AGN are both more frequent and more luminous in higher ${M_*}$ than in lower ${M_*}$ galaxies. The cumulative kinetic luminosity density exerted by radio AGN in SFGs peaks at $z$$\sim$2, and it is mostly driven by galaxies with 10.5$\leq$$\log$(${M_{*}}$/${M_{\odot}}$)$, Comment: Accepted for publication in A&A. 20 pages + Appendices

We studied a sample of 274 radio and X-ray selected quasars (XQSOs) detected in the COSMOS and XXL-S radio surveys at 3 GHz and 2.1 GHz, respectively. This sample was identified by adopting a conservative threshold in X-ray luminosity, Lx [2-10\ keV] >= 10^44 erg/s, selecting only the most powerful quasars. Using available multiwavelength data, we examined various criteria for the selection of radio-loud (RL) and radio-quiet (RQ) XQSOs, finding that the number of RL/RQ XQSOs changes significantly depending on the chosen criterion. This discrepancy arises due to the different criteria tracing different physical processes and due to our sample being selected from flux-limited radio and X-ray surveys. Another approach to study the origin of radio emission in XQSOs is via their radio luminosity function (RLF). We constructed the XQSO 1.4 GHz radio luminosity functions (RLFs) in six redshift bins at 0.5, 14 pages, 11 figures

We study the space density evolution of active galactic nuclei (AGN) using the 610 MHz radio survey of the XXL-North field, performed with the Giant Metrewave Radio Telescope. The survey covers an area of 30.4 deg2, with a beamsize of 6.5 arcsec. The survey is divided into two parts, one covering an area of 11.9 deg2 with 1σ rms noise of 200 μJy beam−1 and the other spanning 18.5 deg2 with rms noise of 45 μJy beam−1. We extracted the catalog of radio components above 7σ. The catalog was cross-matched with a multi-wavelength catalog of the XXL-North field (covering about 80% of the radio XXL-North field) using a likelihood ratio method, which determines the counterparts based on their positions and their optical properties. The multi-component sources were matched visually with the aid of a computer code: Multi-Catalog Visual Cross-Matching. A flux density cut above 1 mJy selects AGN hosts with a high purity in terms of star formation contamination based on the available source counts. After cross-matching and elimination of observational biases arising from survey incompletenesses, the number of remaining sources was 1150. We constructed the rest-frame 1.4 GHz radio luminosity functions of these sources using the maximum volume method. This survey allows us to probe luminosities of 23 ≲ log(L1.4 GHz[W Hz−1]) ≲ 28 up to redshifts of z ≈ 2.1. Our results are consistent with the results from the literature in which AGN are comprised of two differently evolving populations, where the high luminosity end of the luminosity functions evolves more strongly than the low-luminosity end.

($ABRIDGED$) We probe the physical properties and large-scale environment of radio AGN in the faintest FR population to-date, and link them to their radio structure. We use the VLA-COSMOS Large Project at 3 GHz, with resolution and sensitivity of 0".75 and 2.3 $��$Jy/beam, respectively, to explore the FR dichotomy down to $��$Jy levels. We classify objects as FRIs, FRIIs or hybrid FRI/FRII based on the surface-brightness distribution along their radio structure. Our control sample is the jet-less/compact radio AGN (COM AGN) which show excess radio emission at 3 GHz VLA-COSMOS exceeding what is coming from star-formation alone; this sample excludes FRs. Largest angular projected sizes of FR objects are measured by a machine-learning algorithm and also by hand, following a parametric approach to the FR classification. Eddington ratios are calculated using scaling relations from the X-rays, while we include the jet power by using radio luminosity as a probe. We investigate their host properties (star-formation ratio, stellar mass, morphology), and we explore their incidence within X-ray galaxy groups in COSMOS, as well as in the density fields and cosmic-web probes in COSMOS. Our sample is composed of 59 FRIIs, 32 FRI/FRIIs, 39 FRIs, and 1818 COM AGN at 0.03 $\le z \le$ 6. FR objects have on average similar radio luminosities ($L_{\rm 3~GHz}\rm \sim 10^{23}~W~Hz^{-1}~sr^{-1}$), spanning a range of $\rm 10^{21-26}~W~Hz^{-1}~sr^{-1}$, and lie at a median redshift of $z ~\sim ~1$. FRs reside in their majority in massive quenched hosts ($M_{*}~> 10^{10.5} M_{\odot}$), with older episodes of star-formation linked to lower X-ray galaxy group temperatures, suggesting radio-mode AGN quenching. Irrespective of their radio structure, FRs and COM AGN are found in all types and density environments (group or cluster, filaments, field)., 47 pages, 27 figures, 9 tables, 3 appendices, to appear in A&A

As the SKA is expected to be operational in the next decade, investigations of the radio sky in the range of 100 MHz to 10 GHz have become important for simulations of the SKA observations. In determining physical properties of galaxies from radio data, the radio SED is often assumed to be described by a simple power law, usually with a spectral index of 0.7 for all sources. Even though radio SEDs have been shown to exhibit deviations from this assumption, both in differing spectral indices and complex spectral shapes, it is often presumed that their individual differences cancel out in large samples. We constructed the average radio SED of radio-excess active galactic nuclei (RxAGN), defined as those that exhibit a 3 $\sigma$ radio luminosity excess with respect to the value expected only from contribution from star formation, out to z~4. We combined VLA observations of the COSMOS field at 1.4 GHz and 3 GHz with GMRT observations at 325 MHz and 610 MHz. To account for nondetections in the GMRT maps, we employed the survival analysis technique. We selected a sample of RxAGN out to z~4. We find that a sample of RxAGN can be described by a spectral index of $\alpha_1=0.28\pm0.03$ below the break frequency $\nu_b=(4.1\pm0.2)$ GHz and $\alpha_2=1.16\pm0.04$ above, while a simple power-law model yields a single spectral index of $\alpha=0.64\pm0.07$. By binning in 1.4 GHz radio luminosity and redshift, we find that the power-law spectral index, as well as broken power-law spectral indices, may increase for larger source sizes, while the power-law spectral index and lower-frequency (, Comment: 12 pages, 11 figures

We study a sample of 1,604 moderate-to-high radiative luminosity active galactic nuclei (HLAGN) selected at 3 GHz within the VLA-COSMOS 3 GHz Large Project. These were classified by combining multiple AGN diagnostics: X-ray data, mid-infrared data and broad-band spectral energy distribution fitting. We decompose the total radio 1.4 GHz luminosity ($\mathrm{L_{1.4\ GHz,TOT}}$) into the emission originating from star formation and AGN activity by measuring the excess in $\mathrm{L_{1.4\ GHz,TOT}}$ relative to the infrared-radio correlation of star-forming galaxies. To quantify the excess, for each source we calculate the AGN fraction ($\mathrm{f_{AGN}}$), the fractional contribution of AGN activity to $\mathrm{L_{1.4\ GHz,TOT}}$. The majority of the HLAGN, $(68.0\pm1.5)\%$, are dominated by star-forming processes ($f_{AGN}\leq0.5$), while $(32.0\pm1.5)\%$ are dominated by AGN-related radio emission ($0.50$)., Comment: 20 pages, 14 figures

We study the moderate-to-high radiative luminosity active galactic nuclei (HLAGN) within the VLA-COSMOS 3 GHz Large Project. The survey covers 2.6 square degrees centered on the COSMOS field with a 1$\sigma$ sensitivity of 2.3 $\mathrm{\mu Jy}$/beam across the field. This provides the simultaneously largest and deepest radio continuum survey available to date with exquisite multi-wavelength coverage. The survey yields 10,830 radio sources with signal-to-noise ratios $\geq$5. A subsample of 1,604 HLAGN is analyzed here. These were selected via a combination of X-ray luminosity and mid-infrared colors. We derive luminosity functions for these AGN and constrain their cosmic evolution out to a redshift of $z\sim6$, for the first time decomposing the star formation and AGN contributions to the radio continuum emission in the AGN. We study the evolution of number density and luminosity density finding a peak at $z\sim1.5$ followed by a decrease out to a redshift $z\sim6$., Comment: 4 pages, 1 figure, Proceedings of Science, IAU Symposium 333: "Peering towards Cosmic Dawn"

Based on a sample of over 1,800 radio AGN at redshifts out to z~5, which have typical stellar masses within ~3x(10^{10}-10^{11}) Msol, and 3 GHz radio data in the COSMOS field, we derived the 1.4 GHz radio luminosity functions for radio AGN (L_1.4GHz ~ 10^{22}-10^{27} W/Hz) out to z~5. We constrained the evolution of this population via continuous models of pure density and pure luminosity evolutions, and we found best-fit parametrizations of Phi*~(1+z)^{(2.00+/-0.18)-(0.60+/-0.14)z}, and L*~(1+z)^{(2.88+/-0.82)-(0.84+/-0.34)z}, respectively, with a turnover in number and luminosity densities of the population at z~1.5. We converted 1.4 GHz luminosity to kinetic luminosity taking uncertainties of the scaling relation used into account. We thereby derived the cosmic evolution of the kinetic luminosity density provided by the AGN and compared this luminosity density to the radio-mode AGN feedback assumed in the Semi-Analytic Galaxy Evolution (SAGE) model, i.e., to the redshift evolution of the central supermassive black hole accretion luminosity taken in the model as the source of heating that offsets the energy losses of the cooling, hot halo gas, and thereby limits further stellar mass growth of massive galaxies. We find that the kinetic luminosity exerted by our radio AGN may be high enough to balance the radiative cooling of the hot gas at each cosmic epoch since z~5. However, although our findings support the idea of radio-mode AGN feedback as a cosmologically relevant process in massive galaxy formation, many simplifications in both the observational and semi-analytic approaches still remain and need to be resolved before robust conclusions can be reached., Comment: 13 pages, 9 figures, 2 tables, to appear in A&A