Threads, Ribbons, and Rings in the Radio Galaxy IC 4296

Condon, J. J.; Cotton, W. D.; White, Sarah V.; Legodi, L. S.; Goedhart, S.; McAlpine, K.; Ratcliffe, S.; Camilo, F.

doi:10.3847/1538-4357/ac0880

Cited by 34 publications

(32 citation statements)

References 37 publications

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“…With MeerKAT's exceptional combination of sensitivity and resolution, filamentary synchrotron structures are now being discovered in the neighbourhood of radio galaxies (Ramatsoku et al 2020;Condon et al 2021a). Here, we present the first example where a direct interaction between a filament and the jet flow from a radio galaxy may been seen.…”

Section: The Interaction Of Icm Magnetic Filaments and Radio Tailsmentioning

confidence: 99%

The MeerKAT Galaxy Cluster Legacy Survey

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Cotton

Rudnick

et al. 2022

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MeerKAT’s large number (64) of 13.5 m diameter antennas, spanning 8 km with a densely packed 1 km core, create a powerful instrument for wide-area surveys, with high sensitivity over a wide range of angular scales. The MeerKAT Galaxy Cluster Legacy Survey (MGCLS) is a programme of long-track MeerKAT L-band (900−1670 MHz) observations of 115 galaxy clusters, observed for ∼6−10 h each in full polarisation. The first legacy product data release (DR1), made available with this paper, includes the MeerKAT visibilities, basic image cubes at ∼8″ resolution, and enhanced spectral and polarisation image cubes at ∼8″ and 15″ resolutions. Typical sensitivities for the full-resolution MGCLS image products range from ∼3−5 μJy beam−1. The basic cubes are full-field and span 2° × 2°. The enhanced products consist of the inner 1.2° × 1.2° field of view, corrected for the primary beam. The survey is fully sensitive to structures up to ∼10′ scales, and the wide bandwidth allows spectral and Faraday rotation mapping. Relatively narrow frequency channels (209 kHz) are also used to provide H I mapping in windows of 0 < z < 0.09 and 0.19 < z < 0.48. In this paper, we provide an overview of the survey and the DR1 products, including caveats for usage. We present some initial results from the survey, both for their intrinsic scientific value and to highlight the capabilities for further exploration with these data. These include a primary-beam-corrected compact source catalogue of ∼626 000 sources for the full survey and an optical and infrared cross-matched catalogue for compact sources in the primary-beam-corrected areas of Abell 209 and Abell S295. We examine dust unbiased star-formation rates as a function of cluster-centric radius in Abell 209, extending out to 3.5 R 200. We find no dependence of the star-formation rate on distance from the cluster centre, and we observe a small excess of the radio-to-100 μm flux ratio towards the centre of Abell 209 that may reflect a ram pressure enhancement in the denser environment. We detect diffuse cluster radio emission in 62 of the surveyed systems and present a catalogue of the 99 diffuse cluster emission structures, of which 56 are new. These include mini-halos, halos, relics, and other diffuse structures for which no suitable characterisation currently exists. We highlight some of the radio galaxies that challenge current paradigms, such as trident-shaped structures, jets that remain well collimated far beyond their bending radius, and filamentary features linked to radio galaxies that likely illuminate magnetic flux tubes in the intracluster medium. We also present early results from the H I analysis of four clusters, which show a wide variety of H I mass distributions that reflect both sensitivity and intrinsic cluster effects, and the serendipitous discovery of a group in the foreground of Abell 3365.

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Section: The Interaction Of Icm Magnetic Filaments and Radio Tailsmentioning

confidence: 99%

The MeerKAT Galaxy Cluster Legacy Survey

Knowles

Cotton

Rudnick

et al. 2022

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“…In order to examine the possibilities of using a deconvolved Faraday synthesis, the data were also imaged in Obit task MFImage using a maximum fractional bandwidth of 0.3% giving 223 channels across the bandpass, numerous of these were blanked due to radio interference. The deconvolution used the band average channel polarised intensity ( Q 2 + U 2 ) to drive the CLEAN and reduce the sensitivity to depolarisation due to Faraday rotation (Condon et al 2021). A frequency-dependent taper was used to obtain a nearly constant spatial resolution with frequency.…”

Section: Polarisation and Rotation Measurementioning

confidence: 99%

MeerKAT view of the diffuse radio sources in Abell 3667 and their interactions with the thermal plasma

Gasperin

Rudnick

Finoguenov

et al. 2022

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Context. During their lifetimes, galaxy clusters grow through the accretion of matter from the filaments of the large-scale structure and from mergers with other clusters. These mergers release a large amount of energy into the intracluster medium (ICM) through merger shocks and turbulence. These phenomena are associated with the formation of radio sources known as radio relics and radio halos, respectively. Radio relics and halos are unique proxies for studying the complex properties of these dynamically active regions of clusters and the microphysics of the ICM more generally. Aims. Abell 3667 is a spectacular example of a merging system that hosts a large pair of radio relics. Due to its proximity (z = 0.0553) and large mass, the system enables the study of these sources to a uniquely high level of detail. However, being located at Dec = −56.8°, the cluster could only be observed with a limited number of radio facilities. Methods. We observed Abell 3667 with MeerKAT as part of the MeerKAT Galaxy Cluster Legacy Survey. We used these data to study the large-scale emission of the cluster, including its polarisation and spectral properties. The results were then compared with simulations. Results. We present the most detailed view of the radio relic system in Abell 3667 to date, with a resolution reaching 3 kpc. The relics are filled with a network of filaments with different spectral and polarisation properties that are likely associated with multiple regions of particle acceleration and local enhancements of the magnetic field. Conversely, the magnetic field in the space between filaments has strengths close to what would be expected in unperturbed regions at the same cluster-centric distance. Comparisons with magnetohydrodynamic cosmological and Lagrangian simulations support the idea of filaments as multiple acceleration sites. Our observations also confirm the presence of an elongated radio halo, developed in the wake of the bullet-like sub-cluster that merged from the south-east. Finally, we associate the process of magnetic draping with a thin polarised radio source surrounding the remnant of the bullet’s cool core. Conclusions. Our observations have unveiled the complexity of the interplay between the thermal and non-thermal components in the most active regions of a merging cluster. Both the intricate internal structure of radio relics and the direct detection of magnetic draping around the merging bullet are powerful examples of the non-trivial magnetic properties of the ICM. Thanks to its sensitivity to polarised radiation, MeerKAT will be transformational in the study of these complex phenomena.

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“…In order to recover the polarimetry in the presence of the large Faraday rotation of polarized emission, a relatively high spectral resolution was used for Stokes Q and U imaging -a 1% fractional bandwidth resulting in 68 sub-bands across the band. The deconvolution also used the joint polarization CLEAN described in Condon et al (2021). Linear polarization imaging used 50,000 CLEAN components to a depth of 54 µJy beam −1 resulting in an offsource RMS of 10 µJy beam −1 .…”

Section: Deconvolution Of Stokes Q and Umentioning

confidence: 99%

The Curious Case of the "Heartworm" Nebula

Cotton,

Camilo,

Becker

et al. 2022

Preprint

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The curious Galactic features near G357.2−0.2 were observed with the MeerKAT radio interferometer array in the UHF and L bands (0.56-1.68 GHz). There are two possibly related features: a newly identified faint heart-shaped partial shell (the "Heart"), and a series of previously known but now much better imaged narrow, curved features (the "Worm") interior to the heart. Polarized emission suggests that much of the emission is nonthermal and is embedded in a dense plasma. The filaments of the worm appear to be magnetic structures powered by embedded knots that are sites of particle acceleration. The morphology of the worm broadly resembles some known pulsar wind nebulae (PWNe) but there is no known pulsar or PWN which could be powering this structure. We also present eROSITA observations of the field; no part of the nebula is detected in X-rays, but the current limits do not preclude the existence of a pulsar/PWN of intermediate spin-down luminosity.

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Threads, Ribbons, and Rings in the Radio Galaxy IC 4296

Cited by 34 publications

References 37 publications

The MeerKAT Galaxy Cluster Legacy Survey

The MeerKAT Galaxy Cluster Legacy Survey

MeerKAT view of the diffuse radio sources in Abell 3667 and their interactions with the thermal plasma

The Curious Case of the "Heartworm" Nebula

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