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Active galactic nuclei (AGNs) play an integral role in galaxy formation and evolution by influencing galaxies and their environments through radio jet feedback. Historically, interpreting observations of radio galaxies and quantifying radio jet feedback has been challenging due to degeneracies between their physical parameters. In particular, it is well established that different combinations of jet kinetic power and environment density can yield indistinguishable radio continuum properties, including apparent size and Stokes I luminosity. We present an approach to breaking this degeneracy by probing the line-of-sight environment with Faraday rotation. We study this effect in simulations of three-dimensional relativistic magnetohydrodynamic AGN jets in idealized environments with turbulent magnetic fields. We generate synthetic Stokes I emission and Faraday rotation measure (RM) maps, which enable us to distinguish between our simulated sources. We find enhanced RMs near the jet head and lobe edges. We show that increasing the environment density and the average cluster magnetic field strength broadens the distribution of Faraday rotation measure values. We study the depolarization properties of our sources, finding that the hotspot regions depolarize at lower frequencies than the lobes. We quantify the effect of depolarization on the RM distribution, finding that the frequency at which the source is too depolarized to measure the RM distribution accurately is a probe of environmental properties. This technique offers a range of new opportunities for upcoming surveys, including probing radio galaxy environments and determining more accurate estimates of the AGN feedback budget. [ABSTRACT FROM AUTHOR]

We present the discovery of highly collimated radio jets spanning a total of 355 kpc around the nearby elliptical galaxy NGC 2663, and the possible first detection of recollimation on kiloparsec scales. The small distance to the galaxy (∼28.5 Mpc) allows us to resolve portions of the jets to examine their structure. We combine multiwavelength data: radio observations by the Murchison Widefield Array (MWA), the Australian Square Kilometre Array Pathfinder (ASKAP) and the Australia Telescope Compact Array (ATCA), and X-ray data from Chandra, Swift , and SRG/eROSITA. We present intensity, rotation measure, polarization, spectral index, and X-ray environment maps. Regions of the southern jet show simultaneous narrowing and brightening, which can be interpreted as a signature of the recollimation of the jet by external, environmental pressure, though it is also consistent with intermittent active galactic nuclei or complex internal jet structure. X-ray data suggest that the environment is extremely poor; if the jet is indeed recollimating, the large recollimation scale (40 kpc) is consistent with a slow jet in a low-density environment. [ABSTRACT FROM AUTHOR]

We investigate the role of environment on radio galaxy properties by constructing a sample of large (≳100 kpc), nearby (⁠|$z$| < 0.3) radio sources identified as part of the Radio Galaxy Zoo citizen science project. Our sample consists of 16 Fanaroff-Riley Type II (FR-II) sources, 6 FR-I sources, and 1 source with a hybrid morphology. FR-I sources appear to be hosted by more massive galaxies, consistent with previous studies. In the FR-II sample, we compare the degree of asymmetry in radio lobe properties to asymmetry in the radio source environment, quantified through optical galaxy clustering. We find that the length of radio lobes in FR-II sources is anticorrelated with both galaxy clustering and lobe luminosity. These results are in quantitative agreement with predictions from radio source dynamical models and suggest that galaxy clustering provides a useful proxy for the ambient gas density distribution encountered by the radio lobes. [ABSTRACT FROM AUTHOR]

We study the mutual alignment of radio sources within two surveys, Faint Images of the Radio Sky at Twenty-centimetres (FIRST) and TIFR GMRT Sky Survey (TGSS). This is done by producing two position angle catalogues containing the preferential directions of respectively 30 059 and 11 674 extended sources distributed over more than 7000 and 17 000 deg2. The identification of the sources in the FIRST sample was performed in advance by volunteers of the RadioGalaxy Zoo (RGZ) project,while for the TGSS sample it is the result of an automated process presented here. After taking into account systematic effects, marginal evidence of a local alignment on scales smaller than 2.5 deg is found in the FIRST sample. The probability of this happening by chance is found to be less than 2 per cent. Further study suggests that on scales up to 1.5 deg the alignment is maximal. For one third of the sources, the RGZ volunteers identified an optical counterpart. Assuming a flat ⋀ cold dark matter cosmology with Ωm = 0.31,Ω⋀ = 0.69, we convert the maximum angular scale on which alignment is seen into a physical scale in the range [19, 38] Mpc h -1 70 . This result supports recent evidence reported by Taylor and Jagannathan of radio jet alignment in the 1.4 deg2 ELAIS N1 field observed with the Giant Metrewave Radio Telescope. The TGSS sample is found to be too sparsely populated to manifest a similar signal. [ABSTRACT FROM AUTHOR]

The kinetic power of radio jets is a quantity of fundamental importance to studies of the AGN feedback process and radio galaxy physics. A widely used proxy for jet power is the extended radio luminosity. A number of empirical methods have been used to calibrate a scaling relationship between jet power (Q) and radio luminosity (L) of the formlog(Q) = βL log (L) + C. The regression slope has typically been found to be βLL ~ 0.7-0.8. Here we show that the previously reported scaling relations are strongly affected by the confounding variable, distance. We find that in a sample of FRI X-ray cavity systems, after accounting for the mutual distance dependence, the jet power and radio luminosity are only weakly correlated, with slope βL &#8776 0.3: significantly flatter than previously reported. We also find that in previously used samples of high-power sources, no evidence for an intrinsic correlation is present when the effect of distance is accounted for. Using a simple model we show that βL is expected to be significantly lower in samples of FRI radio galaxies than it is for FRIIs, due to the differing dynamics for these two classes of radio source. For FRI X-ray cavity systems the model predicts βL(FRI) ≳ 0.5 in contrast to FRII radio galaxies, for which βL(FRII) ≳ 0.8. We discuss the implications of our finding for studies of radio mode feedback, and radio galaxy physics. [ABSTRACT FROM AUTHOR]

We examine the relationship between source radio luminosity and kinetic power in active galactic nucleusjets. We show that neglecting various loss processes can introduce a systematic bias in the jet powers inferred from radio luminosities for a sample of radio galaxies. This bias can be corrected for by considering source size as well as radio luminosity; effectively the source size acts as a proxy for source age. Based on a sample of Fanaroff–Riley Type II radio sources with jet powers derived from the measured hotspot parameters, we empirically determine a new expression for jet power that accounts for the source size,(Qjet/1036 W) = 1.5+1.8−0.8(L151/1027WHz−1)0.8(1 + z)1.0(D/kpc)0.58±0.17, where D is source size and L151 the 151 MHz radio luminosity. By comparing a flux-limited and volume-limited sample, we show that any derived radio-luminosity–jet-power relation depends sensitively on sample properties, in particular the source size distribution and the size–luminosity correlation inherent in the sample. Such bias will affect the accuracy of the kinetic luminosity function derived from lobe radio luminosities and should be treated with caution. [ABSTRACT FROM AUTHOR]

We use a volume- and flux-limited sample of local radio galaxies with optical counterparts to address the question of how long a typical galaxy spends in radio active and quiescent states. The length of the active phase has a strong dependence on the stellar mass of the host galaxy. Radio sources in the most massive hosts are also retriggered more frequently. The time spent in the active phase has the same dependence on stellar mass as does the gas cooling rate, suggesting the onset of the quiescent phase is due to fuel depletion. We find radio and emission-line active galactic nuclei (AGN) activity to be independent, consistent with these corresponding to different accretion states. [ABSTRACT FROM AUTHOR]