Radio galaxies and feedback from AGN jets

Hardcastle, M. J.; Croston, J. H.

doi:10.48550/arxiv.2003.06137

Cited by 6 publications

(10 citation statements)

References 371 publications

(516 reference statements)

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“…Among the different types of active galactic nuclei (AGN), the radio luminous extragalactic radio sources associated with massive elliptical galaxies and referred to as radio AGN, continue to pose a number of interesting astrophysical questions. These include the triggering of radio AGN activity, the formation of jets squirting out from the AGN with relativistic speeds, its effect on the host galaxy and its subsequent evolution, and relationship of the different radio and optical classification schemes to modes of accretion onto the supermassive black holes which are believed to fuel the AGN activity (e.g., Tadhunter, 2016a;Hardcastle and Croston, 2020). Radio AGN extend in their overall projected linear size from parsec-scales to over a few Mpc, with the largest known radio galaxy so far having a size of about 4.7 Mpc (Machalski et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Energy input from radio sources (radio mode feedback) may be important in regulating star formation in massive galaxies and determining the shape of the high end of the galaxy luminosity function and also determining the balance of heating and cooling in the intracluster medium (ICM) (e.g., Croton et al, 2006;Fabian, 2012). AS the PS and CSS sources are propagating through their host galaxies, they can provide examples of radio mode feedback (e.g., Holt et al, 2008;Morganti et al, 2013;Tadhunter, 2016b;Hardcastle and Croston, 2020). Evidence of interaction with the cold component of the interstellar medium in these galaxies via Hi absorption line studies has been reviewed recently by Morganti and Oosterloo (2018).…”

Section: Introductionmentioning

confidence: 99%

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Compact steep-spectrum and peaked-spectrum radio sources

O'Dea,

Saikia

2020

Preprint

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Compact steep-spectrum (CSS) and peaked spectrum (PS) radio sources are compact, powerful radio sources. The multi-frequency observational properties and current theories are reviewed with emphasis on developments since the earlier review of O'Dea (1998). There are three main hypotheses for the nature of PS and CSS sources. (1) The PS sources might be very young radio galaxies which will evolve into CSS sources on their way to becoming large radio galaxies. (2) The PS and CSS sources might be compact because they are confined (and enhanced in radio power) by interaction with dense gas in their environments. (3) Alternately, the PS sources might be transient or intermittent sources. Each of these hypotheses may apply to individual objects. The relative number in each population will have significant implications for the radio galaxy paradigm. Proper motion studies over long time baselines have helped determine hotspot speeds for over three dozen sources and establish that these are young objects. Multifrequency polarization observations have demonstrated that many CSS/PS sources are embedded in a dense interstellar medium and vigorously interacting with it. The detection of emission line gas aligned with the radio source, and blue-shifted HI absorption and [OIII] emission lines indicates that AGN feedback is present in these objects -possibly driven by the radio source. CSS/PS sources with evidence of episodic AGN over a large range of time-scales have been discussed. The review closes with a discussion of open questions and prospects for the future.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Compact steep-spectrum and peaked-spectrum radio sources

O'Dea,

Saikia

2020

Preprint

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“…However, these initial efforts assumed the distortion to be non-relativistic y-distortion and concluded that a cosmological distribution of cocoons with t j =10 7 yr to be severely constrained due to the COBE CMB spectral distortion limit (Fixsen et al 1996). Our calculations suggest that in a ΛCDM universe with the current cosmological parameters, the global averaged < y >∼ 10 −6 for t j = 10 7 yr. Several improvements are in order to make progress -for example, the assumed jet luminosity of their model may be too high compared to the jet luminosity inferred from individual radio galaxies (Hardcastle & Croston 2020). Also, the efficiency factor will not be a constant but a function of dark matter halo mass.…”

Section: Discussionmentioning

confidence: 99%

Non-thermal Sunyaev–Zeldovich signal from radio galaxy lobes

Acharya

Majumdar

Nath

2021

Monthly Notices of the Royal Astronomical Society

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Energetic electrons in the lobes of radio galaxies make them potential sources for not only radio and X-rays but also Sunyaev-Zeldovich (SZ) distortions in the cosmic microwave background (CMB) radiation. Previous works have discussed the energetics of radio galaxy lobes, but assuming thermal SZ effect, coming from the non-thermal electron population. We use an improved evolutionary model for radio galaxy lobes to estimate the observed parameters such as the radio luminosity and intensity of SZ-distortions at the redshifts of observation. We, further, quantify the effects of various relevant physical parameters of the radio galaxies, such as the jet power, the time scale over which the jet is active, the evolutionary time scale for the lobe, etc on the observed parameters. For current SZ observations towards galaxy clusters, we find that the non-thermal SZ distortions from radio lobes embedded in galaxy clusters can be non-negligible compared to the amount of thermal SZ distortion from the intra-cluster medium and, hence, can not be neglected. We show that small and young (and preferably residing in a cluster environment) radio galaxies offer better prospects for the detection of the non-thermal SZ signal from these sources. We further discuss the limits on different physical parameters for some sources for which SZ effect has been either detected or upper limits are available. The evolutionary models enable us to obtain limits, previously unavailable, on the low energy cut-off of electron spectrum (pmin ∼ 1–2) in order to explain the recent non-thermal SZ detection. Finally, we discuss how future CMB experiments, which would cover higher frequency bands (>400 GHz), may provide clear signatures for non-thermal SZ effect.

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“…The most plausible heating mechanism is mechanical feedback from the AGN hosted by the cluster -in particular, by the brightest cluster galaxy (BCG; see e.g. reviews by Hardcastle & Croston 2020). Evidence of this hypothesis is found in the X-ray cavities observed in a number clusters, on scales approximately coincident with the lobes of the central radio galaxy (e.g.…”

Section: Introductionmentioning

confidence: 99%

Constraining the AGN duty cycle in the cool-core cluster MS 0735.6+7421 with LOFAR data

Biava,

Brienza,

Bonafede

et al. 2021

Preprint

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Context. MS 0735.6+7421 is a galaxy cluster which hosts a central radio galaxy with a very steep spectrum, produced by one of the most powerful known jetted active galactic nuclei (AGN). The radio plasma, ejected at nearly light speed from the central AGN, have displaced the intra-cluster medium, leaving two pairs of cavities observable in the X-ray, associated to two different outbursts, and have distributed energy to the surrounding medium. While the age of the cavities has previously been estimated from the X-rays, no confirmation from the radio data is available. Furthermore, to-date the radio spectrum has only been derived from integrated flux density measurements, without providing the spatial distribution which could help us to understand the nature of this source. Aims. The aim of this work is to perform for the first time a detailed, high-resolution spectral study of the source at radio frequencies and investigate its duty cycle to be compared with previous X-ray estimates. Methods. We use new observations at 144 MHz produced with the LOw Frequency ARray (LOFAR) together with archival data at higher frequencies (235, 325, 610, 1400 and 8500 MHz), to investigate the spectral properties of the source, and we use radiative models to constrain the age of the source. Results. At LOFAR frequency, the source presents two large outer radio lobes, wider than at higher frequencies, and a smaller Intermediate lobe located south-west of the core. A new inspection of X-ray data, allowed us to identify an intermediate cavity, associated with that lobe, indicating the presence of a further phase of jet activity. The radio lobes have a steep spectrum even at LOFAR frequencies, reaching α 610 144 = 2.9 in the outer lobes and α 610 144 = 2.1 in the Intermediate lobe. Fitting the lobe spectra using a single injection model of particle ageing, we derived a total age of the source between 170 and 106 Myr, in agreement with the buoyancy and sound crossing time-scales derived from X-ray data. Thanks to the resolution of the spectral age map we performed, we are able to reconstruct the duty cycle of the source. There were three phases of jet activity, with the AGN being active for most of the time with only brief quiescent phases, ensuring the repeated heating of the central gas. Finally, we estimated the minimum energy inside the outer lobes, finding that a source of additional pressure support must be present to sustain the bubbles against the pressure of the external medium.

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Radio galaxies and feedback from AGN jets

Cited by 6 publications

References 371 publications

Compact steep-spectrum and peaked-spectrum radio sources

Compact steep-spectrum and peaked-spectrum radio sources

Non-thermal Sunyaev–Zeldovich signal from radio galaxy lobes

Constraining the AGN duty cycle in the cool-core cluster MS 0735.6+7421 with LOFAR data

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