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233 results on '"van Weeren R"'

1. 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.

Subjects
LARGE scale structure (Astronomy), GALAXY clusters, RADIO frequency, ANTENNAS (Electronics), X-rays
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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2. Magnetic fields in the outskirts of PSZ2 G096.88+24.18 from a depolarization analysis of radio relics.

Author

De Rubeis, E., Stuardi, C., Bonafede, A., Vazza, F., van Weeren, R. J., de Gasperin, F., and Brüggen, M.

Subjects
GAS distribution, MAGNETIC fields, GALAXY clusters, GALAXY mergers, POWER spectra
Abstract

Context. Radio relics are diffuse, non-thermal radio sources present in a number of merging galaxy clusters. They are characterized by elongated arc-like shapes and highly polarized emission (up to ∼60%) at gigahertz frequencies, and are expected to trace shock waves in the cluster outskirts induced by galaxy cluster mergers. Their polarized emission can be used to study the magnetic field properties of the host cluster. Aims. In this paper, we investigate the polarization properties of the double radio relics in PSZ2 G096.88+24.18 using the rotation measure (RM) synthesis, and try to constrain the characteristics of the magnetic field that reproduce the observed depolarization as a function of resolution (beam depolarization). Our aim is to understand the nature of the low polarization fraction that characterizes the southern relic with respect to the northern relic. Methods. We present new 1–2 GHz Karl G. Jansky Very Large Array (VLA) observations in multiple configurations. We derived the RM and polarization of the two relics by applying the RM synthesis technique, and thus solved for bandwidth depolarization in the wide observing bandwidth. To study the effect of beam depolarization, we degraded the image resolution and studied the decreasing trend of polarization fraction with increasing beam size. Finally, we performed 3D magnetic field simulations using multiple models for the magnetic field power spectrum over a wide range of scales, in order to constrain the characteristics of the cluster magnetic field that can reproduce the observed beam depolarization trend. Results. Using RM synthesis, we obtained a polarization fraction of (18.6 ± 0.3)% for the northern relic and (14.6 ± 0.1)% for the southern one. Having corrected for bandwidth depolarization, and after noticing the absence of relevant complex Faraday spectrum, we inferred that the nature of the depolarization for the southern relic is external, and possibly related to the turbulent gas distribution within the cluster, or to the complex spatial structure of the relic. The best-fit magnetic field power spectrum, which reproduces the observed depolarization trend for the southern relic, was obtained for a turbulent magnetic field model, described by a power spectrum derived from cosmological simulations, and defined within the scales of Λmin = 35 kpc and Λmax = 400 kpc. This yields an average magnetic field of the cluster within 1 Mpc3 volume of ∼2 μG. [ABSTRACT FROM AUTHOR]

Published
2024
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3. 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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4. LOFAR detection of extended emission around a mini halo in the galaxy cluster Abell 1413

Author

Lusetti, G., primary, Bonafede, A., additional, Lovisari, L., additional, Gitti, M., additional, Ettori, S., additional, Cassano, R., additional, Riseley, C. J., additional, Govoni, F., additional, Brüggen, M., additional, Bruno, L., additional, van Weeren, R. J., additional, Botteon, A., additional, Hoang, D. N., additional, Gastaldello, F., additional, Ignesti, A., additional, Rossetti, M., additional, and Shimwell, T. W., additional

Published
2024
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5. Cosmic evolution of FRI and FRII sources out to z = 2.5

Author

de Jong, J. M. G. H. J., primary, Röttgering, H. J. A., additional, Kondapally, R., additional, Mingo, B., additional, van Weeren, R. J., additional, Best, P. N., additional, Morabito, L. K., additional, Magliocchetti, M., additional, Oonk, J. B. R., additional, Villarrubia-Aguilar, A., additional, and Vecchi, F. F., additional

Published
2024
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6. 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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7. 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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8. Cosmological constraints from the Planck cluster catalogue with new multi-wavelength mass calibration from Chandra and CFHT.

Author

Aymerich, G., Douspis, M., Pratt, G. W., Salvati, L., Soubrié, E., Andrade-Santos, F., Forman, W. R., Jones, C., Aghanim, N., Kraft, R., and van Weeren, R. J.

Subjects
LARGE scale structure (Astronomy), GALAXY clusters, CLUSTER sampling, PHYSICAL cosmology, ACCOUNTING methods, COSMIC background radiation
Abstract

We provide a new scaling relation between YSZ, the integrated Sunyaev-Zeldovich signal and M500YX, the cluster mass derived from X-ray observations, using a sample of clusters from the Planck Early Sunyaev-Zeldovich (ESZ) catalogue observed in X-rays by Chandra, and compare it to the results of the Planck collaboration obtained from XMM-Newton observations of a subsample of the ESZ. We calibrated a mass bias on a subset of the Planck cosmological cluster sample using published weak-lensing data from the Canadian Cluster Cosmology Project (CCCP) and Multi Epoch Nearby Cluster Survey (MENeaCS), for the new scaling relation as well as that from the Planck collaboration. We propose a novel method to account for selection effects and find a mass bias of (1 − b) = 0.89 ± 0.04 for the Chandra-calibrated scaling relation, and (1 − b) = 0.76 ± 0.04 for the XMM-Newton-calibrated scaling relation. We applied the scaling relations we derived to the full Planck cosmological cluster sample and obtain new constraints on the cosmological parameters. We find identical constraints regardless of the X-ray sample used, with σ8 = 0.77 ± 0.02, Ωm = 0.31 ± 0.02, and S8 ≡ σ8 √(Ωm/0.3) = 0.78 ± 0.02. We also provide constraints with a redshift evolution of the scaling relation fitted from the data instead of fixing it to the self-similar value. We find a redshift evolution significantly deviating from the self-similar value, leading to a higher value of S8 = 0.81 ± 0.02. We compare our results to those from various cosmological probes, and find that our S8 constraints are competitive with the tightest constraints from the literature. When assuming a self-similar redshift evolution, our constraints are in agreement with most late-time probes and in tension with constraints from the cosmic microwave background (CMB) primary anisotropies. When relaxing the assumption of redshift evolution and fitting it to the data, we find no significant tension with results from either late-time probes or the CMB. [ABSTRACT FROM AUTHOR]

Published
2024
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9. The first high-redshift cavity power measurements of cool-core galaxy clusters with the International LOFAR Telescope.

Author

Timmerman, R., van Weeren, R. J., Botteon, A., Röttgering, H. J. A., Morabito, L. K., and Sweijen, F.

Subjects
*LARGE scale structure (Astronomy), *ACTIVE galactic nuclei, *ACTIVE galaxies, *RADIO galaxies, *GALACTIC evolution, *GALAXY clusters
Abstract

Radio-mode feedback associated with the active galactic nuclei (AGNs) at the cores of galaxy clusters injects a large amount of energy into the intracluster medium (ICM), offsetting radiative losses through X-ray emission. This mechanism prevents the ICM from rapidly cooling down and fueling extreme starburst activity as it accretes onto the central galaxies, and it is therefore a key ingredient in the evolution of galaxy clusters. However, the influence and mode of feedback at high redshifts (z ∼ 1) remains largely unknown. Low-frequency sub-arcsecond-resolution radio observations taken with the International LOFAR Telescope have demonstrated their ability to assist X-ray observations with constraining the energy output from the AGNs (or "cavity power") in galaxy clusters, thereby enabling research at higher redshifts than before. In this pilot project, we tested this hybrid method on a high-redshift (0.6 < z < 1.3) sample of 13 galaxy clusters for the first time with the aim of verifying the performance of this method at these redshifts and providing the first estimates of the cavity power associated with the central AGN for a sample of distant clusters. We were able to detect clear radio lobes in three out of 13 galaxy clusters at redshifts of 0.7 < z < 0.9, and we used these detections in combination with ICM pressures surrounding the radio lobes obtained from standard profiles to calculate the corresponding cavity powers of the AGNs. Combining our results with the literature, the current data appear to suggest that the average cavity power peaked at a redshift of z ∼ 0.4 and slowly decreases toward higher redshifts. However, we require more and tighter constraints on the cavity volume and a better understanding of our observational systematics to confirm any deviation of the cavity power trend from a constant level. [ABSTRACT FROM AUTHOR]

Published
2024
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10. 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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11. 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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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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14. 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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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. VICTORIA project: The LOFAR HBA Virgo Cluster Survey

Author

Edler, H. W., primary, de Gasperin, F., additional, Shimwell, T. W., additional, Hardcastle, M. J., additional, Boselli, A., additional, Heesen, V., additional, McCall, H., additional, Bomans, D. J., additional, Brüggen, M., additional, Bulbul, E., additional, Chyży, K. T., additional, Ignesti, A., additional, Merloni, A., additional, Pacaud, F., additional, Reiprich, T. H., additional, Roberts, I. D., additional, Rottgering, H. J. A., additional, and van Weeren, R. J., additional

Published
2023
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20. 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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22. 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., Brüggen, M., van Weeren, R. J., Simionescu, A., Brunetti, G., Cassano, R., Forman, W. R., Hoeft, M., Ignesti, A., Röttgering, H. J. A., and Shimwell, T. W.

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present the peculiar case of PSZ2G091.83+26.11 at z=0.822. This cluster hosts a Mpc-scale radio halo and an elongated radio source, whose location with the respect to the intracluster medium (ICM) distribution and to the cluster centre is not consistent with a simple merger scenario. We use VLA data at 1-4 GHz to investigate the spectral and polarisation properties of the diffuse radio emission. We combine them with previously published data from LOFAR n the 120-168 MHz band, and from the uGMRT at 250-500 and 550-900 MHz. We also complement the radio data with Chandra X-ray observations to compare the thermal and non-thermal emission of the cluster. The elongated radio emission is visible up to 3.0 GHz and has an integrated spectral index of $-1.24\pm0.03$, with a steepening from $-0.89\pm0.03$ to $-1.39\pm0.03$. These values correspond to Mach numbers $\mathcal{M}_{\rm radio,int}=3.0\pm0.19$ and $\mathcal{M}_{\rm radio,inj}=2.48\pm0.15$. Chandra data reveals a surface brightness discontinuity at the location of the radio source, with a compression factor of $\mathcal{C}=2.22^{+0.39}_{-0.30}$ (i.e. $\mathcal{M}_{\rm Xray}=1.93^{+0.42}_{-0.32}$). We also find that the source is polarised at GHz frequencies. We estimate an intrinsic polarisation fraction of $\sim0.2$, a Rotation Measure of $\sim50~{\rm rad~m^{-2}}$ (including the Galactic contribution) and an external depolarisation of $\sim60~{\rm rad~m^{-2}}$. The $B$-vectors are aligned with the major axis of the source, suggesting magnetic field compression. Hence, we classify this source as a radio relic. We also find a linear/super-linear correlation between the non-thermal and thermal emission. We propose an off-axis merger and/or multiple merger events to explain the position and orientation of the relic. Given the properties of the radio relic, we speculate that PSZ2G091.83+26.11 is in a fairly young merger state., Comment: 21 pages, 17 figures, 9 tables; accepted for publication in Astronomy & Astrophysics

Published
2023
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23. 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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24. 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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25. 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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26. Piercing the dusty veil of hyper-luminous infrared galaxies: Sub-arcsecond 144 MHz ILT observations of HLIRGs in the Lockman Hole

Author

Sweijen, F., primary, Lyu, Y., additional, Wang, L., additional, Gao, F., additional, Röttgering, H. J. A., additional, van Weeren, R. J., additional, Morabito, L. K., additional, Best, P. N., additional, Małek, K., additional, Williams, W., additional, Prandoni, I., additional, Bonato, M., additional, and Bondi, M., additional

Published
2023
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27. V-LoTSS: The circularly polarised LOFAR Two-metre Sky Survey

Author

Callingham, J. R., primary, Shimwell, T. W., additional, Vedantham, H. K., additional, Bassa, C. G., additional, O’Sullivan, S. P., additional, Yiu, T. W. H., additional, Bloot, S., additional, Best, P. N., additional, Hardcastle, M. J., additional, Haverkorn, M., additional, Kavanagh, R. D., additional, Lamy, L., additional, Pope, B. J. S., additional, Röttgering, H. J. A., additional, Schwarz, D. J., additional, Tasse, C., additional, van Weeren, R. J., additional, White, G. J., additional, Zarka, P., additional, Bomans, D. J., additional, Bonafede, A., additional, Bonato, M., additional, Botteon, A., additional, Bruggen, M., additional, Chyży, K. T., additional, Drabent, A., additional, Emig, K. L., additional, Gloudemans, A. J., additional, Gürkan, G., additional, Hajduk, M., additional, Hoang, D. N., additional, Hoeft, M., additional, Iacobelli, M., additional, Kadler, M., additional, Kunert-Bajraszewska, M., additional, Mingo, B., additional, Morabito, L. K., additional, Nair, D. G., additional, Pérez-Torres, M., additional, Ray, T. P., additional, Riseley, C. J., additional, Rowlinson, A., additional, Shulevski, A., additional, Sweijen, F., additional, Timmerman, R., additional, Vaccari, M., additional, and Zheng, J., additional

Published
2023
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28. 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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31. Possible discovery of Calvera’s supernova remnant

Author

Arias, M., primary, Botteon, A., additional, Bassa, C. G., additional, van der Jagt, S., additional, van Weeren, R. J., additional, O’Sullivan, S. P., additional, Bosschaart, Q., additional, Dullaart, R. S., additional, Hardcastle, M. J., additional, Hessels, J. W. T., additional, Shimwell, T., additional, Slob, M. M., additional, Sturm, J. A., additional, Tasse, C., additional, Theijssen, N. C. M. A., additional, and Vink, J., additional

Published
2022
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32. Seeing the forest and the trees

Author

Kukreti, P., Morganti, R., Bondi, M., Oosterloo, T., Tadhunter, C., Morabito, L. K., Adams, E. A. K., Adebahr, B., de Blok, W. J. G., de Gasperin, F., Drabent, A., Hess, Kelley M., Ivashina, M. V., Kutkin, A., Mika, Á. M., Oostrum, L. C., Shimwell, T. W., van der Hulst, J. M., van Leeuwen, J., van Weeren, R. J., Vohl, D., Ziemke, J., High Energy Astrophys. & Astropart. Phys (API, FNWI), Astronomy, Kapteyn Astronomical Institute, Ministerio de Ciencia e Innovación (España), European Research Council, and European Commission

Subjects
jets, interactions, techniques, galaxies, galaxies, Astrophysics::High Energy Astrophysical Phenomena, Mrk 273, galaxies: active, FOS: Physical sciences, active, Astrophysics::Cosmology and Extragalactic Astrophysics, radio continuum, galaxies: individual: Mrk 273, jets, galaxies, galaxies, galaxies: interactions, individual, Astrophysics::Galaxy Astrophysics, high angular resolution, Astrophysics - Astrophysics of Galaxies, radio continuum: galaxies, techniques: high angular resolution, Astronomy and Astrophysics, interactions, galaxies: jets, Astrophysics - Astrophysics of Galaxies, Mrk 273, galaxies, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), techniques, active, radio continuum, high angular resolution
Abstract

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Galaxy mergers have been observed to trigger nuclear activity by feeding gas to the central supermassive black hole. One such class of objects are Ultra Luminous InfraRed Galaxies (ULIRGs), which are mostly late stage major mergers of gas-rich galaxies. Recently, large-scale (∼100 kpc) radio continuum emission has been detected in a select number of ULIRGs, all of which also harbour powerful Active Galactic Nuclei (AGN). This hints at the presence of large-scale radio emission being evidence for nuclear activity. Exploring the origin of this radio emission and its link to nuclear activity requires high sensitivity multi-frequency data. We present such an analysis of the ULIRG Mrk 273. Using the International LOFAR telescope (ILT), we detected spectacular large-scale arcs in this system. This detection includes, for the first time, a giant ∼190 kpc arc in the north. We propose these arcs are fuelled by a low power radio AGN triggered by the merger. We also identified a bright ∼45 kpc radio ridge, which is likely related to the ionised gas nebula in that region. We combined this with high sensitivity data from APERture Tile In Focus (Apertif) and archival data from the Very Large Array (VLA) to explore the spectral properties. The ILT simultaneously allowed us to probe the nucleus at a resolution of ∼0.3″, where we detected three components, and, for the first time, diffuse emission around these components. Combining this with archival high frequency VLA images of the nucleus allowed us to detect absorption in one component, and a steep spectrum radio AGN in another. We then extrapolate from this case study to the importance of investigating the presence of radio emission in more ULIRGs and what it can tell us about the link between mergers and the presence of radio activity. © P. Kukreti et al. 2022., LOFAR, the Low Frequency Array designed and constructed by ASTRON, has facilities in several countries, that are owned by various parties (each with their own funding sources), and that are collectively operated by the International LOFAR Telescope (ILT) foundation under a joint scientific policy. This work makes use of data from the Apertif system installed at the Westerbork Synthesis Radio Telescope owned by ASTRON. ASTRON, the Netherlands Institute for Radio Astronomy, is an institute of the Dutch Science Organisation (De Nederlandse Organisatie voor Wetenschappelijk Onderzoek, NWO). This work was supported by the Medical Research Council [MR/T042842/1]. CT acknowledges support from STFC. AD acknowledges support by the BMBF Verbundforschung under the grant 05A20STA. RJvW acknowledges support from the ERC Starting Grant ClusterWeb 804208. FdG acknowledges support from the Deutsche Forschungsgemeinschaft under Germany’s Excellence Strategy – EXC 2121 “Quantum Universe” – 390833306. EAKA is supported by the WISE research programme, which is financed by the Dutch Research Council (NWO). JvL acknowledges funding from Vici research programme ‘ARGO’ with project number 639.043.815, financed by the Dutch Research Council (NWO). LCO acknowledges funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 617199. DV acknowledges support from the Netherlands eScience Center (NLeSC) under grant ASDI.15.406. JMvdH acknowledges funding from the Europeaní Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 291531 (‘HIStoryNU’). The Jülich LOFAR Long Term Archive and the German LOFAR network are both coordinated and operated by the Jülich Supercomputing Centre (JSC), and computing resources on the supercomputer JUWELS at JSC were provided by the Gauss Centre for Supercomputing e.V. (grant CHTB00) through the John von Neumann Institute for Computing (NIC). KMH acknowledges funding from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the “Center of Excellence Severo Ochoa” awarded to the Instituto de Astrofísica de Andalucía (SEV-2017-0709); from grant RTI2018-096228-B-C31 (Ministry of Science, Innovation and Universities/State Agency for Research/European Regional Development Funds, European Union); and from the coordination of the participation in SKA-SPAIN, funded by the Ministry of Science and innovation (MICIN).

Published
2022

35. Diffuse radio emission from non-Planckgalaxy clusters in the LoTSS-DR2 fields

Author

Hoang, D. N., primary, Brüggen, M., additional, Botteon, A., additional, Shimwell, T. W., additional, Zhang, X., additional, Bonafede, A., additional, Bruno, L., additional, Bonnassieux, E., additional, Cassano, R., additional, Cuciti, V., additional, Drabent, A., additional, de Gasperin, F., additional, Gastaldello, F., additional, Di Gennaro, G., additional, Hoeft, M., additional, Jones, A., additional, Pignataro, G. V., additional, Röttgering, H. J. A., additional, Simionescu, A., additional, and van Weeren, R. J., additional

Published
2022
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37. Filamentary structures of ionized gas in Cygnus X

Author

Emig, K. L., primary, White, G. J., additional, Salas, P., additional, Karim, R. L., additional, van Weeren, R. J., additional, Teuben, P. J., additional, Zavagno, A., additional, Chiu, P., additional, Haverkorn, M., additional, Oonk, J. B. R., additional, Orrú, E., additional, Polderman, I. M., additional, Reich, W., additional, Röttgering, H. J. A., additional, and Tielens, A. G. G. M., additional

Published
2022
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38. Seeing the forest and the trees: A radio investigation of the ULIRG Mrk 273

Author

Ministerio de Ciencia e Innovación (España), European Research Council, European Commission, Kukreti, P., Morganti, R., Bondi, M., Oosterloo, T., Tadhunter, C., Morabito, L. K., Adams, E. A. K., Adebahr, B., de Blok, W. J. G., de Gasperin, F., Drabent, A., Hess, Kelley M., Ivashina, M. V., Kutkin, A., Mika, Á. M., Oostrum, L. C., Shimwell, T. W., van der Hulst, J. M., van Leeuwen, J., van Weeren, R. J., Vohl, D., Ziemke, J., Ministerio de Ciencia e Innovación (España), European Research Council, European Commission, Kukreti, P., Morganti, R., Bondi, M., Oosterloo, T., Tadhunter, C., Morabito, L. K., Adams, E. A. K., Adebahr, B., de Blok, W. J. G., de Gasperin, F., Drabent, A., Hess, Kelley M., Ivashina, M. V., Kutkin, A., Mika, Á. M., Oostrum, L. C., Shimwell, T. W., van der Hulst, J. M., van Leeuwen, J., van Weeren, R. J., Vohl, D., and Ziemke, J.

Abstract

Galaxy mergers have been observed to trigger nuclear activity by feeding gas to the central supermassive black hole. One such class of objects are Ultra Luminous InfraRed Galaxies (ULIRGs), which are mostly late stage major mergers of gas-rich galaxies. Recently, large-scale (∼100 kpc) radio continuum emission has been detected in a select number of ULIRGs, all of which also harbour powerful Active Galactic Nuclei (AGN). This hints at the presence of large-scale radio emission being evidence for nuclear activity. Exploring the origin of this radio emission and its link to nuclear activity requires high sensitivity multi-frequency data. We present such an analysis of the ULIRG Mrk 273. Using the International LOFAR telescope (ILT), we detected spectacular large-scale arcs in this system. This detection includes, for the first time, a giant ∼190 kpc arc in the north. We propose these arcs are fuelled by a low power radio AGN triggered by the merger. We also identified a bright ∼45 kpc radio ridge, which is likely related to the ionised gas nebula in that region. We combined this with high sensitivity data from APERture Tile In Focus (Apertif) and archival data from the Very Large Array (VLA) to explore the spectral properties. The ILT simultaneously allowed us to probe the nucleus at a resolution of ∼0.3″, where we detected three components, and, for the first time, diffuse emission around these components. Combining this with archival high frequency VLA images of the nucleus allowed us to detect absorption in one component, and a steep spectrum radio AGN in another. We then extrapolate from this case study to the importance of investigating the presence of radio emission in more ULIRGs and what it can tell us about the link between mergers and the presence of radio activity. © P. Kukreti et al. 2022.

Published
2022

39. 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

40. 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

41. 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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42. 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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43. The eROSITA Final Equatorial-Depth Survey (eFEDS)

Author

Pasini, T., primary, Brüggen, M., additional, Hoang, D. N., additional, Ghirardini, V., additional, Bulbul, E., additional, Klein, M., additional, Liu, A., additional, Shimwell, T. W., additional, Hardcastle, M. J., additional, Williams, W. L., additional, Botteon, A., additional, Gastaldello, F., additional, van Weeren, R. J., additional, Merloni, A., additional, de Gasperin, F., additional, Bahar, Y. E., additional, Pacaud, F., additional, and Ramos-Ceja, M., additional

Published
2022
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44. 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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45. 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
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46. Sub-arcsecond imaging with the International LOFAR Telescope

Author

Jackson, N., Badole, S., Morgan, J., Chhetri, R., Prūsis, K., Nikolajevs, A., Morabito, L., Brentjens, M., Sweijen, F., Iacobelli, M., Orrù, E., Sluman, J., Blaauw, R., Mulder, H., van Dijk, P., Mooney, S., Deller, A., Moldon, J., Callingham, J. R., Harwood, J., Hardcastle, M., Heald, G., Drabent, A., McKean, J. P., Asgekar, A., Avruch, I. M., Bentum, M. J., Bonafede, A., Brouw, W. N., Brüggen, M., Butcher, H. R., Ciardi, B., Coolen, A., Corstanje, A., Damstra, S., Duscha, S., Eislöffel, J., Falcke, H., Garrett, M., de Gasperin, F., Griessmeier, J.-M., Gunst, A. W., van Haarlem, M. P., Hoeft, M., van der Horst, A. J., Jütte, E., Koopmans, L. V. E., Krankowski, A., Maat, P., Mann, G., Miley, G. K., Nelles, A., Norden, M., Paas, M., Pandey, V. N., Pandey-Pommier, M., Pizzo, R. F., Reich, W., Rothkaehl, H., Rowlinson, A., Ruiter, M., Shulevski, A., Schwarz, D. J., Smirnov, O., Tagger, M., Vocks, C., van Weeren, R. J., Wijers, R., Wucknitz, O., Zarka, P., Zensus, J. A., and Zucca, P.

Subjects
ddc:520
Abstract

Astronomy and astrophysics 658, A2 (2022). doi:10.1051/0004-6361/202140756, The Low-Frequency Array (LOFAR) Long-Baseline Calibrator Survey (LBCS) was conducted between 2014 and 2019 in order to obtain a set of suitable calibrators for the LOFAR array. In this paper, we present the complete survey, building on the preliminary analysis published in 2016 which covered approximately half the survey area. The final catalogue consists of 30 006 observations of 24 713 sources in the northern sky, selected for a combination of high low-frequency radio flux density and flat spectral index using existing surveys (WENSS, NVSS, VLSS, and MSSS). Approximately one calibrator per square degree, suitable for calibration of ≥200 km baselines is identified by the detection of compact flux density, for declinations north of 30° and away from the Galactic plane, with a considerably lower density south of this point due to relative difficulty in selecting flat-spectrum candidate sources in this area of the sky. The catalogue contains indicators of degree of correlated flux on baselines between the Dutch core and each of the international stations, involving a maximum baseline length of nearly 2000 km, for all of the observations. Use of the VLBA calibrator list, together with statistical arguments by comparison with flux densities from lower-resolution catalogues, allow us to establish a rough flux density scale for the LBCS observations, so that LBCS statistics can be used to estimate compact flux densities on scales between 300 mas and 2′′, for sources observed in the survey. The survey is used to estimate the phase coherence time of the ionosphere for the LOFAR international baselines, with median phase coherence times of about 2 min varying by a few tens of percent between theshortest and longest baselines. The LBCS can be used to assess the structures of point sources in lower-resolution surveys, with significant reductions in the degree of coherence in these sources on scales between 2′′ and 300 mas. The LBCS survey sources show a greater incidence of compact flux density in quasars than in radio galaxies, consistent with unified schemes of radio sources. Comparison with samples of sources from interplanetary scintillation (IPS) studies with the Murchison Widefield Array shows consistent patterns of detection of compact structure in sources observed both interferometrically with LOFAR and using IPS., Published by EDP Sciences, Les Ulis

Published
2022
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47. 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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48. 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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49. LoTSS jellyfish galaxies

Author

Roberts, I. D., primary, van Weeren, R. J., additional, Timmerman, R., additional, Botteon, A., additional, Gendron-Marsolais, M., additional, Ignesti, A., additional, and Rottgering, H. J. A., additional

Published
2022
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50. 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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