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193 results on '"Brunetti G."'

1. Probing particle acceleration in Abell 2256: from 16 MHz to gamma rays

Author

Osinga, E., primary, van Weeren, R.J., additional, Brunetti, G., additional, Adam, R., additional, Rajpurohit, K., additional, Botteon, A., additional, Callingham, J.R., additional, Cuciti, V., additional, de Gasperin, F., additional, Miley, G.K., additional, Röttgering, H.J.A., additional, and Shimwell, T.W., additional

Published
2024
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2. Mind the gap between A2061 and A2067: Unveiling new diffuse, large-scale radio emission.

Author

Pignataro, G. V., Bonafede, A., Bernardi, G., Balboni, M., Vazza, F., van Weeren, R. J., Ubertosi, F., Cassano, R., Brunetti, G., Botteon, A., Venturi, T., Akamatsu, H., Drabent, A., and Hoeft, M.

Abstract

Aims. The clusters Abell 2061 and Abell 2067 in the Corona Borealis supercluster have been studied at different radio frequencies and are both known to host diffuse radio emission. The aim of this work is to investigate the radio emission between them, whose presence is suggested by low-resolution observations. Methods. We analysed deep LOw Frequency ARray (LOFAR) High Band Antenna (HBA) observations at 144 MHz to follow up on the possible inter-cluster filament suggested by previous 1.4 GHz observations. We investigated the radial profiles and the point-to-point surface-brightness correlation of the emission in Abell 2061 with radio and X-ray observations to describe the nature of the diffuse emission. Results. We report the detection of diffuse radio emission on an 800 kpc scale, which is more extended than previously known, reaching beyond the radio halo in Abell 2061 towards Abell 2067 and over the separation outside the two clusters R500 radii. We confirm the presence of a radio halo in A2061, while we do not find evidence of diffuse emission in Abell 2067. The surface-brightness profile from the centre of A2061 shows an excess of emission with respect to the azimuthally averaged radio halo profile and X-ray background. We explored three different dynamical scenarios to explain the nature of the diffuse emission. Additionally, we analysed a trail of emission of ∼760 kpc between the radio halo and radio relic in Abell 2061. Conclusions. This dynamically interacting, pre-merger system closely resembles the two other cluster pairs where radio bridges connecting the radio halos on Megaparsecs scales have been detected. The diffuse emission extends beyond each cluster R500 radius, but in this unique case the absence of the radio halo in Abell 2067 is likely the reason for the observed 'gap' between the two systems. However, the point-to-point correlation results are challenging to explain. The classification of the emission remains unclear, and detailed spectral analysis and further X-ray observations are required to understand the origin of the diffuse emission. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Ageing and dynamics of the tailed radio galaxies in Abell 2142.

Author

Bruno, L., Venturi, T., Dallacasa, D., Brienza, M., Ignesti, A., Brunetti, G., Riseley, C. J., Rossetti, M., Gastaldello, F., Botteon, A., Rudnick, L., van Weeren, R. J., Shulevski, A., and Lal, D. V.

Subjects
RADIO galaxies, ACTIVE galactic nuclei, RADIO telescopes, HYDRODYNAMICS, MEERKAT
Abstract

Context. Tailed radio galaxies are shaped by ram pressure that is due to the high-velocity motion of their host through the intracluster medium (ICM). Recent works have reported on the increasing complexity of the phenomenology of tailed galaxies, with departures from theoretical ageing models and novel evidence of re-energising mechanisms that are nonetheless unclear. Aims. The nearby (z = 0.0894) galaxy cluster Abell 2142 hosts two tailed galaxies, namely T1 and T2, which exhibit peculiar morphological features. We aim to investigate the properties of T1 and T2 and constrain their spectral evolution, dynamics, and interactions with the ICM. Methods. We combined data from LOw Frequency Array (LOFAR), upgraded Giant Metrewave Radio Telescope (uGMRT), Very Large Array (VLA), and MeerKAT (from 30 MHz to 6.5 GHz) to carry out a detailed spectral analysis of T1 and T2. We analysed the surface brightness profiles, measured integrated and spatially resolved spectral indices. We performed a comparison with single injection ageing models. The Chandra X-ray data were used to search for discontinuities in the ICM properties in the direction of the targets. Results. The spectral properties of T1 at low frequencies can be predicted by ageing models and provide constraints on the 3D dynamics of the host by assuming a constant velocity. However, a more complex scenario is suggested by the sharp transitions along sub-regions of the tail, local surface brightness enhancements, and a spectral shape at high frequencies that is not predicted by any of the models. This scenario may plausibly involve hydrodynamical instabilities and particle mixing. T2 exhibits unusual morphological and surface brightness features, and its spectral behaviour is not predicted by standard models. The effects of two active galactic nucleus (AGN) outburst events during the infall of T2 towards the cluster centre could potentially explain its characteristic properties. [ABSTRACT FROM AUTHOR]

Published
2024
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4. The prototypical major cluster merger Abell 754: I. Calibration of MeerKAT data and radio/X-ray spectral mapping of the cluster.

Author

Botteon, A., van Weeren, R. J., Eckert, D., Gastaldello, F., Markevitch, M., Giacintucci, S., Brunetti, G., Kale, R., and Venturi, T.

Subjects
GRAVITATIONAL energy, MERGERS & acquisitions, THERMAL shock, THERMAL electrons, GALAXY clusters
Abstract

Context. Abell 754 is a rich galaxy cluster at z = 0.0543 and is considered the prototype of a major cluster merger. As many dynamically unrelaxed systems, it hosts diffuse radio emission on megaparsec-scales. Extended synchrotron sources in the intra-cluster medium (ICM) are commonly interpreted as evidence that a fraction of the gravitational energy released during cluster mergers is dissipated into nonthermal components. Aims. Here, we aim to use new MeerKAT UHF- and L-band observations to study nonthermal phenomena in Abell 754. These data are complemented with archival XMM-Newton observations to investigate the resolved spectral properties of both the radio and X-ray cluster emission. Methods. For the first time, we employed the pipeline originally developed to calibrate LOFAR data to MeerKAT observations. This allowed us to perform a direction-dependent calibration and obtain highly sensitive radio images in UHF and L bands that capture the extended emission with unprecedented detail. By using a large XMM-Newton mosaic, we produced thermodynamic maps of the ICM. Results. Our analysis reveals that the radio halo in the cluster center is bounded by the well-known shock in the eastern direction. Furthermore, in the southwest periphery, we discover an extended radio source that we classify as a radio relic that is possibly tracing a shock driven by the squeezed gas compressed by the merger, outflowing in perpendicular directions. The low-luminosity of this relic appears compatible with direct acceleration of thermal pool electrons. We interpret the observed radio and X-ray features in the context of a major cluster merger with a nonzero impact parameter. Conclusions. Abell 754 is a remarkable galaxy cluster showcasing exceptional features associated with the ongoing merger event. The high quality of the new MeerKAT data motivates further work on this system. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Cosmological simulations of the generation of cluster-scale radio emission from turbulent re-acceleration.

Author

Beduzzi, L., Vazza, F., Cuciti, V., Brunetti, G., Brüggen, M., and Wittor, D.

Subjects
LARGE scale structure (Astronomy), COSMIC rays, INTERSTELLAR medium, MERGERS & acquisitions, MAGNETIC fields, GALAXY clusters
Abstract

Context. The recent discovery of so-called mega radio halos as a new class of diffuse, steep-spectrum radio sources in clusters of galaxies has raised questions about the origin and the evolution of cluster-wide radio emission. Aims. We investigate whether the formation mechanisms of radio halos and mega radio halos differ, or whether they can be produced by different modalities of the same (re-)acceleration mechanism. Here we present results of a cosmological simulation of a disturbed galaxy cluster, with the aim to study the origin of mega radio halos. Methods. We analysed the evolution of cosmic-ray electrons (CRe), subject to gains and losses using a Fokker-Planck solver. In particular, we included the effects of adiabatic stochastic acceleration (ASA) which is caused by the stochastic interaction of cosmic rays with diffusing magnetic field lines in super-Alfvenic turbulence. Moreover, we included shock acceleration and the seeding of CRe by galaxies. Results. Our simulations generate cluster-scale radio sources during mergers, with properties that are in agreement with those observed for real radio halos. Furthermore, we find evidence of additional emission on larger scales. This emission resembles the radial distribution and the spectrum of a mega radio halo, but only when viewed close to the merger axis. Conclusions. In our simulation, the mechanism responsible for the formation of diffuse radio emission, both in the form of classical and mega radio halos, is cosmic-ray re-acceleration by turbulence. This turbulence is more solenoidal and more subsonic in the classical radio halo region, than in the mega radio halo region. [ABSTRACT FROM AUTHOR]

Published
2024
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6. CHEX-MATE: A LOFAR pilot X-ray -radio study on five radio halo clusters

Author

Balboni, M., primary, Gastaldello, F., additional, Bonafede, A., additional, Botteon, A., additional, Bartalucci, I., additional, Bourdin, H., additional, Brunetti, G., additional, Cassano, R., additional, De Grandi, S., additional, De Luca, F., additional, Ettori, S., additional, Ghizzardi, S., additional, Gitti, M., additional, Iqbal, A., additional, Johnston-Hollitt, M., additional, Lovisari, L., additional, Mazzotta, P., additional, Molendi, S., additional, Pointecouteau, E., additional, Pratt, G.W., additional, Riva, G., additional, Rossetti, M., additional, Rottgering, H., additional, Sereno, M., additional, van Weeren, R.J., additional, Venturi, T., additional, and Veronesi, I., additional

Published
2024
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7. First evidence of a connection between cluster-scale diffuse radio emission in cool-core galaxy clusters and sloshing features

Author

Biava, N., primary, Bonafede, A., additional, Gastaldello, F., additional, Botteon, A., additional, Brienza, M., additional, Shimwell, T.W., additional, Brunetti, G., additional, Bruno, L., additional, Rajpurohit, K., additional, Riseley, C.J., additional, van Weeren, R.J., additional, Rossetti, M., additional, Cassano, R., additional, De Gasperin, F., additional, Drabent, A., additional, Rottgering, H.J.A., additional, Edge, A.C., additional, and Tasse, C., additional

Published
2024
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8. LOFAR HBA observations of the Euclid Deep Field North (EDFN)

Author

Bondi, M., primary, Scaramella, R., additional, Zamorani, G., additional, Ciliegi, P., additional, Vitello, F., additional, Arias, M., additional, Best, P. N., additional, Bonato, M., additional, Botteon, A., additional, Brienza, M., additional, Brunetti, G., additional, Hardcastle, M. J., additional, Magliocchetti, M., additional, Massaro, F., additional, Morabito, L. K, additional, Pentericci, L., additional, Prandoni, I., additional, Röttgering, H. J. A., additional, Shimwell, T. W., additional, Tasse, C., additional, van Weeren, R. J., additional, and White, G. J., additional

Published
2024
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9. The Planck clusters in the LOFAR sky

Author

Jones, A., primary, de Gasperin, F., additional, Cuciti, V., additional, Botteon, A., additional, Zhang, X., additional, Gastaldello, F., additional, Shimwell, T., additional, Simionescu, A., additional, Rossetti, M., additional, Cassano, R., additional, Akamatsu, H., additional, Bonafede, A., additional, Brüggen, M., additional, Brunetti, G., additional, Camillini, L., additional, Di Gennaro, G., additional, Drabent, A., additional, Hoang, D. N., additional, Rajpurohit, K., additional, Natale, R., additional, Tasse, C., additional, and van Weeren, R. J., additional

Published
2023
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10. The Planck clusters in the LOFAR sky

Author

Cuciti, V., primary, Cassano, R., additional, Sereno, M., additional, Brunetti, G., additional, Botteon, A., additional, Shimwell, T. W., additional, Bruno, L., additional, Gastaldello, F., additional, Rossetti, M., additional, Zhang, X., additional, Simionescu, A., additional, Brüggen, M., additional, van Weeren, R. J., additional, Jones, A., additional, Akamatsu, H., additional, Bonafede, A., additional, De Gasperin, F., additional, Di Gennaro, G., additional, Pasini, T., additional, and Röttgering, H. J. A., additional

Published
2023
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11. Abell 0399–Abell 0401 radio bridge spectral index: First multi-frequency detection.

Author

Pignataro, G. V., Bonafede, A., Bernardi, G., de Gasperin, F., Brunetti, G., Pasini, T., Vazza, F., Biava, N., de Jong, J. M. G. H. J., Cassano, R., Botteon, A., Brüggen, M., Röttgering, H. J. A., van Weeren, R. J., and Shimwell, T. W.

Subjects
BRIDGES, PARTICLE acceleration, MAGNETIC structure, RELATIVISTIC electrons, GALAXY clusters, MAGNETIC particles
Abstract

Aims. Recent low-frequency radio observations at 140 MHz discovered a bridge of diffuse emission with a length of 3 Mpc that connects the galaxy clusters Abell 0399 and Abell 0401. We present follow-up observations at 60 MHz to constrain the spectral index of the bridge, which has only been detected at 140 and 144 MHz so far. Methods. We analysed deep (∼18 h) LOw Frequency ARray (LOFAR) Low Band Antenna (LBA) data at 60 MHz to detect the bridge at very low frequencies. We then conducted a multi-frequency study with LOFAR HBA data at 144 MHz and uGMRT data at 400 MHz. Assuming second-order Fermi mechanisms for the re-acceleration of relativistic electrons driven by turbulence in the radio bridge regions, we compared the observed radio spectrum with theoretical synchrotron models. Results. The bridge is detected in the 75″ resolution LOFAR image at 60 MHz, and its emission fully connects the region between the two galaxy clusters. Between 60 MHz and 144 MHz, we found an integrated spectral index value of α60144 = −1.44 ± 0.16 for the bridge emission. For the first time, we produced spectral index and related uncertainties maps for a radio bridge. We produce a radio spectrum that shows a significant steepening between 144 and 400 MHz. Conclusions. This detection at low frequencies provides important information for models of particle acceleration and magnetic field structure on very extended scales. The spectral index gives important clues about the origin of inter-cluster diffuse emission. The steepening of the spectrum above 144 MHz can be explained in a turbulent re-acceleration framework, assuming that the acceleration timescales are longer than ∼200 Myr. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Shock imprints on the radio mini halo in RBS 797

Author

Bonafede, A., primary, Gitti, M., additional, La Bella, N., additional, Biava, N., additional, Ubertosi, F., additional, Brunetti, G., additional, Lusetti, G., additional, Brienza, M., additional, Riseley, C. J., additional, Stuardi, C., additional, Botteon, A., additional, Ignesti, A., additional, Rottgering, H., additional, and van Weeren, R. J., additional

Published
2023
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15. A three-component giant radio halo: The puzzling case of the galaxy cluster Abell 2142

Author

Bruno, L., primary, Botteon, A., additional, Shimwell, T., additional, Cuciti, V., additional, de Gasperin, F., additional, Brunetti, G., additional, Dallacasa, D., additional, Gastaldello, F., additional, Rossetti, M., additional, van Weeren, R. J., additional, Venturi, T., additional, Russo, S. A., additional, Taffoni, G., additional, Cassano, R., additional, Biava, N., additional, Lusetti, G., additional, Bonafede, A., additional, Ghizzardi, S., additional, and De Grandi, S., additional

Published
2023
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17. The diffuse radio emission in the high-redshift cluster PSZ2 G091.83+26.11: Total intensity and polarisation analysis with Very Large Array 1-4 GHz observations

Author

Di Gennaro, G., primary, Brüggen, M., additional, van Weeren, R.J., additional, Simionescu, A., additional, Brunetti, G., additional, Cassano, R., additional, Forman, W.R., additional, Hoeft, M., additional, Ignesti, A., additional, Röttgering, H.J.A., additional, and Shimwel, T.W., additional

Published
2023
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18. The LOFAR LBA Sky Survey

Author

de Gasperin, F., primary, Edler, H. W., additional, Williams, W. L., additional, Callingham, J. R., additional, Asabere, B., additional, Brüggen, M., additional, Brunetti, G., additional, Dijkema, T. J., additional, Hardcastle, M. J., additional, Iacobelli, M., additional, Offringa, A., additional, Norden, M. J., additional, Röttgering, H. J. A., additional, Shimwell, T., additional, van Weeren, R. J., additional, Tasse, C., additional, Bomans, D. J., additional, Bonafede, A., additional, Botteon, A., additional, Cassano, R., additional, Chyży, K. T., additional, Cuciti, V., additional, Emig, K. L., additional, Kadler, M., additional, Miley, G., additional, Mingo, B., additional, Oei, M. S. S. L., additional, Prandoni, I., additional, Schwarz, D. J., additional, and Zarka, P., additional

Published
2023
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20. The Planck clusters in the LOFAR sky

Author

Zhang, X., primary, Simionescu, A., additional, Gastaldello, F., additional, Eckert, D., additional, Camillini, L., additional, Natale, R., additional, Rossetti, M., additional, Brunetti, G., additional, Akamatsu, H., additional, Botteon, A., additional, Cassano, R., additional, Cuciti, V., additional, Bruno, L., additional, Shimwell, T. W., additional, Jones, A., additional, Kaastra, J. S., additional, Ettori, S., additional, Brüggen, M., additional, de Gasperin, F., additional, Drabent, A., additional, van Weeren, R. J., additional, and Röttgering, H. J. A., additional

Published
2023
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21. The Planck clusters in the LOFAR sky

Author

Bruno, L., primary, Brunetti, G., additional, Botteon, A., additional, Cuciti, V., additional, Dallacasa, D., additional, Cassano, R., additional, van Weeren, R. J., additional, Shimwell, T., additional, Taffoni, G., additional, Russo, S. A., additional, Bonafede, A., additional, Brüggen, M., additional, Hoang, D. N., additional, Rottgering, H. J. A., additional, and Tasse, C., additional

Published
2023
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22. The Planck clusters in the LOFAR sky

Author

Cassano, R., primary, Cuciti, V., additional, Brunetti, G., additional, Botteon, A., additional, Rossetti, M., additional, Bruno, L., additional, Simionescu, A., additional, Gastaldello, F., additional, van Weeren, R. J., additional, Brüggen, M., additional, Dallacasa, D., additional, Zhang, X., additional, Akamatsu, H., additional, Bonafede, A., additional, Di Gennaro, G., additional, Shimwell, T. W., additional, de Gasperin, F., additional, Röttgering, H. J. A., additional, and Jones, A., additional

Published
2023
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24. Deep low-frequency radio observations of Abell 2256

Author

Rajpurohit, K., primary, Osinga, E., additional, Brienza, M., additional, Botteon, A., additional, Brunetti, G., additional, Forman, W. R., additional, Riseley, C. J., additional, Vazza, F., additional, Bonafede, A., additional, van Weeren, R. J., additional, Brüggen, M., additional, Rajpurohit, S., additional, Drabent, A., additional, Dallacasa, D., additional, Rossetti, M., additional, Rajpurohit, A. S., additional, Hoeft, M., additional, Bonnassieux, E., additional, Cassano, R., additional, and Miley, G. K., additional

Published
2022
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27. The LOFAR Two-metre Sky Survey

Author

Shimwell, T. W., Hardcastle, M. J., Tasse, C., Best, P. N., Röttgering, H. J. A., Williams, W. L., Botteon, A., Drabent, A., Mechev, A., Shulevski, A., van Weeren, R. J., Bester, L., Brüggen, M., Brunetti, G., Callingham, J. R., Chyży, K. T., Conway, J. E., Dijkema, T. J., Duncan, K., de Gasperin, F., Hale, C. L., Haverkorn, M., Hugo, B., Jackson, N., Mevius, M., Miley, G. K., Morabito, L. K., Morganti, R., Offringa, A., Oonk, J. B. R., Rafferty, D., Sabater, J., Smith, D. J. B., Schwarz, D. J., Smirnov, O., O’Sullivan, S. P., Vedantham, H., White, G. J., Albert, J. G., Alegre, L., Asabere, B., Bacon, D. J., Bonafede, A., Bonnassieux, E., Brienza, M., Bilicki, M., Bonato, M., Calistro Rivera, G., Cassano, R., Cochrane, R., Croston, J. H., Cuciti, V., Dallacasa, D., Danezi, A., Dettmar, R. J., Di Gennaro, G., Edler, H. W., Enßlin, T. A., Emig, K. L., Franzen, T. M. O., García-Vergara, C., Grange, Y. G., Gürkan, G., Hajduk, M., Heald, G., Heesen, V., Hoang, D. N., Hoeft, M., Horellou, C., Iacobelli, M., Jamrozy, M., Jelić, V., Kondapally, R., Kukreti, P., Kunert-Bajraszewska, M., Magliocchetti, M., Mahatma, V., Małek, K., Mandal, S., Massaro, F., Meyer-Zhao, Z., Mingo, B., Mostert, R. I. J., Nair, D. G., Nakoneczny, S. J., Nikiel-Wroczyński, B., Orrú, E., Pajdosz-Śmierciak, U., Pasini, T., Prandoni, I., van Piggelen, H. E., Rajpurohit, K., Retana-Montenegro, E., Riseley, C. J., Rowlinson, A., Saxena, A., Schrijvers, C., Sweijen, F., Siewert, T. M., Timmerman, R., Vaccari, M., Vink, J., West, J. L., Wołowska, A., Zhang, X., and Zheng, J.

Subjects
Astrophysics::Cosmology and Extragalactic Astrophysics
Abstract

In this data release from the ongoing LOw-Frequency ARray (LOFAR) Two-metre Sky Survey we present 120–168 MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m +44◦300 and 1h00m +28◦000 and spanning 4178 and 1457 square degrees respectively. The images were derived from 3451 h (7.6 PB) of LOFAR High Band Antenna data which were corrected for the direction-independent instrumental properties as well as direction-dependent ionospheric distortions during extensive, but fully automated, data processing. A catalogue of 4 396 228 radio sources is derived from our total intensity (Stokes I) maps, where the majority of these have never been detected at radio wavelengths before. At 600 resolution, our full bandwidth Stokes I continuum maps with a central frequency of 144 MHz have: a median rms sensitivity of 83 µJy beam−1 ; a flux density scale accuracy of approximately 10%; an astrometric accuracy of 0.200; and we estimate the point-source completeness to be 90% at a peak brightness of 0.8 mJy beam−1 . By creating three 16 MHz bandwidth images across the band we are able to measure the in-band spectral index of many sources, albeit with an error on the derived spectral index of >±0.2 which is a consequence of our flux-density scale accuracy and small fractional bandwidth. Our circular polarisation (Stokes V) 2000 resolution 120–168 MHz continuum images have a median rms sensitivity of 95 µJy beam−1 , and we estimate a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation (Stokes Q and Stokes U) image cubes consist of 480 × 97.6 kHz wide planes and have a median rms sensitivity per plane of 10.8 mJy beam−1 at 40 and 2.2 mJy beam−1 at 2000; we estimate the Stokes I to Stokes Q/U leakage to be approximately 0.2%. Here we characterise and publicly release our Stokes I, Q, U and V images in addition to the calibrated uv-data to facilitate the thorough scientific exploitation of this unique dataset.

Published
2022

28. Origin of the ring structures in Hercules A: Sub-arcsecond 144 MHz to 7 GHz observations

Author

European Commission, European Research Council, Ministerio de Ciencia e Innovación (España), Timmerman, R., van Weeren, R. J., Callingham, J. R., Cotton, W. D., Perley, R., Morabito, L. K., Gizani, N. A. B., Bridle, A. H., O'Dea, C.P., Baum, S. A., Tremblay, G. R., Kharb, P., Kassim, N. E., Röttgering, H. J. A., Botteon, A., Sweijen, F., Tasse, C., Brüggen, M., Moldón, Javier, Shimwell, T., Brunetti, G., European Commission, European Research Council, Ministerio de Ciencia e Innovación (España), Timmerman, R., van Weeren, R. J., Callingham, J. R., Cotton, W. D., Perley, R., Morabito, L. K., Gizani, N. A. B., Bridle, A. H., O'Dea, C.P., Baum, S. A., Tremblay, G. R., Kharb, P., Kassim, N. E., Röttgering, H. J. A., Botteon, A., Sweijen, F., Tasse, C., Brüggen, M., Moldón, Javier, Shimwell, T., and Brunetti, G.

Abstract

The prominent radio source Hercules A features complex structures in its radio lobes. Although it is one of the most comprehensively studied sources in the radio sky, the origin of the ring structures in the Hercules A radio lobes remains an open question. We present the first sub-arcsecond angular resolution images at low frequencies (<300 MHz) of Hercules A, made with the International LOFAR Telescope. With the addition of data from the Karl G. Jansky Very Large Array, we mapped the structure of the lobes from 144 MHz to 7 GHz. We explore the origin of the rings within the lobes of Hercules A, and test whether their properties are best described by a shock model, where shock waves are produced by the jet propagating in the radio lobe, or by an inner-lobe model, where the rings are formed by decelerated jetted plasma. From spectral index mapping our large frequency coverage reveals that the curvature of the different ring spectra increases with distance away from the central active galactic nucleus. We demonstrate that the spectral shape of the rings is consistent with synchrotron aging, which speaks in favor of an inner-lobe model where the rings are formed from the deposition of material from past periods of intermittent core activity. © R. Timmerman et al. 2022.

Published
2022

29. Pushing sub-arcsecond resolution imaging down to 30 MHz with the trans-European International LOFAR Telescope

Author

European Research Council, European Commission, Ministerio de Ciencia e Innovación (España), UK Research and Innovation, Netherlands Organization for Scientific Research, Groeneveld, C., van Weeren, R. J., Miley, George K., Morabito, L. K., de Gasperin, F., Callingham, J. R., Sweijen, F., Brüggen, M., Botteon, A., Offringa, A., Brunetti, G., Moldón, Javier, Bondi, M., Kappes, A., Röttgering, H. J. A., European Research Council, European Commission, Ministerio de Ciencia e Innovación (España), UK Research and Innovation, Netherlands Organization for Scientific Research, Groeneveld, C., van Weeren, R. J., Miley, George K., Morabito, L. K., de Gasperin, F., Callingham, J. R., Sweijen, F., Brüggen, M., Botteon, A., Offringa, A., Brunetti, G., Moldón, Javier, Bondi, M., Kappes, A., and Röttgering, H. J. A.

Abstract

Relatively little information is available about the Universe at ultra-low radio frequencies (ULF; i.e., below 50 MHz), although the ULF spectral window contains a wealth of unique diagnostics for studying galactic and extragalactic phenomena. Subarcsecond resolution imaging at these frequencies is extremely difficult, due to the long baselines (>1000 km) required and large ionospheric perturbations. We have conducted a pilot project to investigate the ULF performance and potential of the International LOFAR Telescope (ILT), a trans-European interferometric array with baselines up to ~2000 km and observing frequencies down to 10 MHz. We have successfully produced images with subarcsecond resolution for six radio sources at frequencies down to 30 MHz. This resolution is more than an order of magnitude better than pre-ILT observations at similar frequencies. The six targets that we imaged (3C 196, 3C 225, 3C 273, 3C 295, 3C 298, and 3C 380) are bright radio sources with compact structures. By comparing our data of 3C 196 and 3C 273 with observations at higher frequencies, we investigate their spatially resolved radio spectral properties. Our success shows that at frequencies down to 30 MHz, subarcsecond imaging with the ILT is possible. Further analysis is needed to determine the feasibility of observations of fainter sources or sources with less compact emission. © ESO 2022.

Published
2022

30. Particle re-acceleration and diffuse radio sources in the galaxy cluster Abell 1550

Author

Pasini, T., primary, Edler, H.W., additional, Brüggen, M., additional, de Gasperin, F., additional, Botteon, A., additional, Rajpurohit, K., additional, van Weeren, R. J., additional, Gastaldello, F., additional, Gaspari, M., additional, Brunetti, G., additional, Cuciti, V., additional, Nanci, C., additional, di Gennaro, G., additional, Rossetti, M., additional, Dallacasa, D., additional, Hoang, D. N., additional, and Riseley, C. J., additional

Published
2022
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31. The galaxy group NGC 507: Newly detected AGN remnant plasma transported by sloshing

Author

Brienza, M., primary, Lovisari, L., additional, Rajpurohit, K., additional, Bonafede, A., additional, Gastaldello, F., additional, Murgia, M., additional, Vazza, F., additional, Bonnassieux, E., additional, Botteon, A., additional, Brunetti, G., additional, Drabent, A., additional, Hardcastle, M. J., additional, Pasini, T., additional, Riseley, C. J., additional, Röttgering, H. J. A., additional, Shimwell, T., additional, Simionescu, A., additional, and van Weeren, R. J., additional

Published
2022
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32. The Planck clusters in the LOFAR sky

Author

Botteon, A., primary, Shimwell, T. W., additional, Cassano, R., additional, Cuciti, V., additional, Zhang, X., additional, Bruno, L., additional, Camillini, L., additional, Natale, R., additional, Jones, A., additional, Gastaldello, F., additional, Simionescu, A., additional, Rossetti, M., additional, Akamatsu, H., additional, van Weeren, R. J., additional, Brunetti, G., additional, Brüggen, M., additional, Groeneveld, C., additional, Hoang, D. N., additional, Hardcastle, M. J., additional, Ignesti, A., additional, Di Gennaro, G., additional, Bonafede, A., additional, Drabent, A., additional, Röttgering, H. J. A., additional, Hoeft, M., additional, and de Gasperin, F., additional

Published
2022
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33. A LOFAR view into the stormy environment of the galaxy cluster 2A0335+096

Author

Ignesti, A., primary, Brunetti, G., additional, Shimwell, T., additional, Gitti, M., additional, Birzan, L., additional, Botteon, A., additional, Brüggen, M., additional, de Gasperin, F., additional, Di Gennaro, G., additional, Edge, A. C., additional, Riseley, C. J., additional, Röttgering, H. J. A., additional, and van Weeren, R. J., additional

Published
2022
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34. The LOFAR Two-metre Sky Survey

Author

Shimwell, T. W., primary, Hardcastle, M. J., additional, Tasse, C., additional, Best, P. N., additional, Röttgering, H. J. A., additional, Williams, W. L., additional, Botteon, A., additional, Drabent, A., additional, Mechev, A., additional, Shulevski, A., additional, van Weeren, R. J., additional, Bester, L., additional, Brüggen, M., additional, Brunetti, G., additional, Callingham, J. R., additional, Chyży, K. T., additional, Conway, J. E., additional, Dijkema, T. J., additional, Duncan, K., additional, de Gasperin, F., additional, Hale, C. L., additional, Haverkorn, M., additional, Hugo, B., additional, Jackson, N., additional, Mevius, M., additional, Miley, G. K., additional, Morabito, L. K., additional, Morganti, R., additional, Offringa, A., additional, Oonk, J. B. R., additional, Rafferty, D., additional, Sabater, J., additional, Smith, D. J. B., additional, Schwarz, D. J., additional, Smirnov, O., additional, O’Sullivan, S. P., additional, Vedantham, H., additional, White, G. J., additional, Albert, J. G., additional, Alegre, L., additional, Asabere, B., additional, Bacon, D. J., additional, Bonafede, A., additional, Bonnassieux, E., additional, Brienza, M., additional, Bilicki, M., additional, Bonato, M., additional, Calistro Rivera, G., additional, Cassano, R., additional, Cochrane, R., additional, Croston, J. H., additional, Cuciti, V., additional, Dallacasa, D., additional, Danezi, A., additional, Dettmar, R. J., additional, Di Gennaro, G., additional, Edler, H. W., additional, Enßlin, T. A., additional, Emig, K. L., additional, Franzen, T. M. O., additional, García-Vergara, C., additional, Grange, Y. G., additional, Gürkan, G., additional, Hajduk, M., additional, Heald, G., additional, Heesen, V., additional, Hoang, D. N., additional, Hoeft, M., additional, Horellou, C., additional, Iacobelli, M., additional, Jamrozy, M., additional, Jelić, V., additional, Kondapally, R., additional, Kukreti, P., additional, Kunert-Bajraszewska, M., additional, Magliocchetti, M., additional, Mahatma, V., additional, Małek, K., additional, Mandal, S., additional, Massaro, F., additional, Meyer-Zhao, Z., additional, Mingo, B., additional, Mostert, R. I. J., additional, Nair, D. G., additional, Nakoneczny, S. J., additional, Nikiel-Wroczyński, B., additional, Orrú, E., additional, Pajdosz-Śmierciak, U., additional, Pasini, T., additional, Prandoni, I., additional, van Piggelen, H. E., additional, Rajpurohit, K., additional, Retana-Montenegro, E., additional, Riseley, C. J., additional, Rowlinson, A., additional, Saxena, A., additional, Schrijvers, C., additional, Sweijen, F., additional, Siewert, T. M., additional, Timmerman, R., additional, Vaccari, M., additional, Vink, J., additional, West, J. L., additional, Wołowska, A., additional, Zhang, X., additional, and Zheng, J., additional

Published
2022
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35. Origin of the ring structures in Hercules A

Author

Timmerman, R., primary, van Weeren, R. J., additional, Callingham, J. R., additional, Cotton, W. D., additional, Perley, R., additional, Morabito, L. K., additional, Gizani, N. A. B., additional, Bridle, A. H., additional, O’Dea, C. P., additional, Baum, S. A., additional, Tremblay, G. R., additional, Kharb, P., additional, Kassim, N. E., additional, Röttgering, H. J. A., additional, Botteon, A., additional, Sweijen, F., additional, Tasse, C., additional, Brüggen, M., additional, Moldon, J., additional, Shimwell, T., additional, and Brunetti, G., additional

Published
2022
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36. Pushing sub-arcsecond resolution imaging down to 30 MHz with the trans-European International LOFAR Telescope

Author

Groeneveld, C., primary, van Weeren, R. J., additional, Miley, G. K., additional, Morabito, L. K., additional, de Gasperin, F., additional, Callingham, J. R., additional, Sweijen, F., additional, Brüggen, M., additional, Botteon, A., additional, Offringa, A., additional, Brunetti, G., additional, Moldon, J., additional, Bondi, M., additional, Kappes, A., additional, and Röttgering, H. J. A., additional

Published
2022
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37. Turbulent magnetic fields in the merging galaxy cluster MACS J0717.5+3745

Author

Rajpurohit, K., primary, Hoeft, M., additional, Wittor, D., additional, van Weeren, R. J., additional, Vazza, F., additional, Rudnick, L., additional, Rajpurohit, S., additional, Forman, W. R., additional, Riseley, C. J., additional, Brienza, M., additional, Bonafede, A., additional, Rajpurohit, A. S., additional, Domínguez-Fernández, P., additional, Eilek, J., additional, Bonnassieux, E., additional, Brüggen, M., additional, Loi, F., additional, Röttgering, H. J. A., additional, Drabent, A., additional, Locatelli, N., additional, Botteon, A., additional, Brunetti, G., additional, and Clarke, T. E., additional

Published
2021
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38. A 3.5 Mpc long radio relic in the galaxy cluster ClG 0217+70

Author

Hoang, D. N., primary, Zhang, X., additional, Stuardi, C., additional, Shimwell, T. W., additional, Bonafede, A., additional, Brüggen, M., additional, Brunetti, G., additional, Botteon, A., additional, Cassano, R., additional, de Gasperin, F., additional, Di Gennaro, G., additional, Hoeft, M., additional, Intema, H., additional, Rajpurohit, K., additional, Röttgering, H. J. A., additional, Simionescu, A., additional, and van Weeren, R. J., additional

Published
2021
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39. Dissecting nonthermal emission in the complex multiple-merger galaxy cluster Abell 2744: Radio and X-ray analysis

Author

Rajpurohit, K., primary, Vazza, F., additional, van Weeren, R. J., additional, Hoeft, M., additional, Brienza, M., additional, Bonnassieux, E., additional, Riseley, C. J., additional, Brunetti, G., additional, Bonafede, A., additional, Brüggen, M., additional, Formann, W. R., additional, Rajpurohit, A. S., additional, Röttgering, H. J. A., additional, Drabent, A., additional, Domínguez-Fernández, P., additional, Wittor, D., additional, and Andrade-Santos, F., additional

Published
2021
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40. A LOFAR-uGMRT spectral index study of distant radio halos

Author

Di Gennaro, G., primary, van Weeren, R. J., additional, Cassano, R., additional, Brunetti, G., additional, Brüggen, M., additional, Hoeft, M., additional, Osinga, E., additional, Botteon, A., additional, Cuciti, V., additional, de Gasperin, F., additional, Röttgering, H. J. A., additional, and Tasse, C., additional

Published
2021
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41. Abell 1430: A merging cluster with exceptional diffuse radio emission

Author

Hoeft, M., primary, Dumba, C., additional, Drabent, A., additional, Rajpurohit, K., additional, Rossetti, M., additional, Nuza, S. E., additional, van Weeren, R. J., additional, Meusinger, H., additional, Botteon, A., additional, Brunetti, G., additional, Shimwell, T. W., additional, Cassano, R., additional, Brüggen, M., additional, Röttgering, H. J. A., additional, Gastaldello, F., additional, Lovisari, L., additional, Yepes, G., additional, Andrade-Santos, F., additional, and Eckert, D., additional

Published
2021
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43. LOFAR observations of galaxy clusters in HETDEX

Author

van Weeren, R. J., primary, Shimwell, T. W., additional, Botteon, A., additional, Brunetti, G., additional, Brüggen, M., additional, Boxelaar, J. M., additional, Cassano, R., additional, Di Gennaro, G., additional, Andrade-Santos, F., additional, Bonnassieux, E., additional, Bonafede, A., additional, Cuciti, V., additional, Dallacasa, D., additional, de Gasperin, F., additional, Gastaldello, F., additional, Hardcastle, M. J., additional, Hoeft, M., additional, Kraft, R. P., additional, Mandal, S., additional, Rossetti, M., additional, Röttgering, H. J. A., additional, Tasse, C., additional, and Wilber, A. G., additional

Published
2021
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44. The LOFAR and JVLA view of the distant steep spectrum radio halo in MACS J1149.5+2223

Author

Bruno, L., primary, Rajpurohit, K., additional, Brunetti, G., additional, Gastaldello, F., additional, Botteon, A., additional, Ignesti, A., additional, Bonafede, A., additional, Dallacasa, D., additional, Cassano, R., additional, van Weeren, R. J., additional, Cuciti, V., additional, Di Gennaro, G., additional, Shimwell, T., additional, and Brüggen, M., additional

Published
2021
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45. Nonthermal phenomena in the center of Abell 1775

Author

Botteon, A., primary, Giacintucci, S., additional, Gastaldello, F., additional, Venturi, T., additional, Brunetti, G., additional, van Weeren, R. J., additional, Shimwell, T. W., additional, Rossetti, M., additional, Akamatsu, H., additional, Brüggen, M., additional, Cassano, R., additional, Cuciti, V., additional, de Gasperin, F., additional, Drabent, A., additional, Hoeft, M., additional, Mandal, S., additional, Röttgering, H. J. A., additional, and Tasse, C., additional

Published
2021
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46. The LOFAR LBA Sky Survey

Author

de Gasperin, F., primary, Williams, W. L., additional, Best, P., additional, Brüggen, M., additional, Brunetti, G., additional, Cuciti, V., additional, Dijkema, T. J., additional, Hardcastle, M. J., additional, Norden, M. J., additional, Offringa, A., additional, Shimwell, T., additional, van Weeren, R., additional, Bomans, D., additional, Bonafede, A., additional, Botteon, A., additional, Callingham, J. R., additional, Cassano, R., additional, Chyży, K. T., additional, Emig, K. L., additional, Edler, H., additional, Haverkorn, M., additional, Heald, G., additional, Heesen, V., additional, Iacobelli, M., additional, Intema, H. T., additional, Kadler, M., additional, Małek, K., additional, Mevius, M., additional, Miley, G., additional, Mingo, B., additional, Morabito, L. K., additional, Sabater, J., additional, Morganti, R., additional, Orrú, E., additional, Pizzo, R., additional, Prandoni, I., additional, Shulevski, A., additional, Tasse, C., additional, Vaccari, M., additional, Zarka, P., additional, and Röttgering, H., additional

Published
2021
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47. The LOFAR Two-meter Sky Survey: Deep Fields Data Release 1

Author

Tasse, C., primary, Shimwell, T., additional, Hardcastle, M. J., additional, O’Sullivan, S. P., additional, van Weeren, R., additional, Best, P. N., additional, Bester, L., additional, Hugo, B., additional, Smirnov, O., additional, Sabater, J., additional, Calistro-Rivera, G., additional, de Gasperin, F., additional, Morabito, L. K., additional, Röttgering, H., additional, Williams, W. L., additional, Bonato, M., additional, Bondi, M., additional, Botteon, A., additional, Brüggen, M., additional, Brunetti, G., additional, Chyży, K. T., additional, Garrett, M. A., additional, Gürkan, G., additional, Jarvis, M. J., additional, Kondapally, R., additional, Mandal, S., additional, Prandoni, I., additional, Repetti, A., additional, Retana-Montenegro, E., additional, Schwarz, D. J., additional, Shulevski, A., additional, and Wiaux, Y., additional

Published
2021
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48. Diffuse radio emission from galaxy clusters in the LOFAR Two-metre Sky Survey Deep Fields

Author

Osinga, E., primary, van Weeren, R. J., additional, Boxelaar, J. M., additional, Brunetti, G., additional, Botteon, A., additional, Brüggen, M., additional, Shimwell, T. W., additional, Bonafede, A., additional, Best, P. N., additional, Bonato, M., additional, Cassano, R., additional, Gastaldello, F., additional, di Gennaro, G., additional, Hardcastle, M. J., additional, Mandal, S., additional, Rossetti, M., additional, Röttgering, H. J. A., additional, Sabater, J., additional, and Tasse, C., additional

Published
2021
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49. Radio halos in a mass-selected sample of 75 galaxy clusters

Author

Cuciti, V., primary, Cassano, R., additional, Brunetti, G., additional, Dallacasa, D., additional, de Gasperin, F., additional, Ettori, S., additional, Giacintucci, S., additional, Kale, R., additional, Pratt, G. W., additional, van Weeren, R. J., additional, and Venturi, T., additional

Published
2021
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50. Radio observations of the merging galaxy cluster system Abell 3391-Abell 3395

Author

Brüggen, M., primary, Reiprich, T. H., additional, Bulbul, E., additional, Koribalski, B. S., additional, Andernach, H., additional, Rudnick, L., additional, Hoang, D. N., additional, Wilber, A. G., additional, Duchesne, S. W., additional, Veronica, A., additional, Pacaud, F., additional, Hopkins, A. M., additional, Norris, R. P., additional, Johnston-Hollitt, M., additional, Brown, M. J. I., additional, Bonafede, A., additional, Brunetti, G., additional, Collier, J. D., additional, Sanders, J. S., additional, Vardoulaki, E., additional, Venturi, T., additional, Kapinska, A. D., additional, and Marvil, J., additional

Published
2021
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