Publications (24)
The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
T. W. Shimwell, H. J. A. Röttgering, P. N. Best +69
The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168 MHz imaging survey that will eventually cover the entire Northern sky. Each of the 3170 pointings will be observed for 8 hr…
LOFAR discovery of an ultra-steep radio halo and giant head-tail radio galaxy in Abell 1132
A. Wilber, M. Brüggen, A. Bonafede +16
LOFAR observations at 144 MHz have revealed large-scale radio sources in the unrelaxed galaxy cluster Abell 1132. The cluster hosts diffuse radio emission on scales of 650 kp…
The LOFAR Two-metre Sky Survey: VII. Third Data Release
T. W. Shimwell, M. J. Hardcastle, C. Tasse +99
We present the third data release of the LOFAR Two-metre Sky Survey (LoTSS-DR3). The survey images cover 88% of the northern sky and were created from 12,950 hrs of data (18.6 PB)…
Ultra-steep spectrum emission in the merging galaxy cluster Abell 1914
S. Mandal, H. T. Intema, T. W. Shimwell +14
A number of radio observations have revealed the presence of large synchrotron-emitting sources associated with the intra-cluster medium. There is strong observational evidence tha…
The powerful outburst in Hercules A
P. E. J. Nulsen, D. C. Hambrick, B. R. McNamara +4
The radio source Hercules A resides at the center of a cooling flow cluster of galaxies at redshift z = 0.154. A Chandra X-ray image reveals a shock front in the intracluster mediu…
The LOFAR Two-metre Sky Survey -- V. Second data release
T. W. Shimwell, M. J. Hardcastle, C. Tasse +103
In this data release from the LOFAR Two-metre Sky Survey (LoTSS) we present 120-168MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at ap…
The brightness and spatial distributions of terrestrial radio sources
A. R. Offringa, A. G. de Bruyn, S. Zaroubi +75
Faint undetected sources of radio-frequency interference (RFI) might become visible in long radio observations when they are consistently present over time. Thereby, they might obs…
Investigating ionospheric calibration for LOFAR 2.0 with simulated observations
H. W. Edler, F. de Gasperin, D. Rafferty
A number of hardware upgrades for the Low-Frequency Array (LOFAR) are currently under development. These upgrades are collectively referred to as the LOFAR 2.0 upgrade. The first s…
LOFAR: The LOw-Frequency ARray
M. P. van Haarlem, M. W. Wise, A. W. Gunst +197
LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in the north of the Netherlands and across europe. Utilizing a novel phased-array design, LOFAR…
Reaching thermal noise at ultra-low radio frequencies: the Toothbrush radio relic downstream of the shock front
F. de Gasperin, G. Brunetti, M. Bruggen +14
Ultra-low frequency observations (<100 MHz) are particularly challenging because they are usually performed in a low signal-to-noise ratio regime due to the high sky temperature an…
Systematic effects in LOFAR data: A unified calibration strategy
F. de Gasperin, T. J. Dijkema, A. Drabent +17
Context: New generation low-frequency telescopes are exploring a new parameter space in terms of depth and resolution. The data taken with these interferometers, for example with t…
The Extended Chandra Deep Field-South Survey: Optical spectroscopy of faint X-ray sources with the VLT and Keck
J. D. Silverman, V. Mainieri, M. Salvato +26
We present the results of a program to acquire high-quality optical spectra of X-ray sources detected in the E-CDF-S and its central area. New spectroscopic redshifts are measured…
M87 at metre wavelengths: the LOFAR picture
F. de Gasperin, E. Orru', M. Murgia +92
M87 is a giant elliptical galaxy located in the centre of the Virgo cluster, which harbours a supermassive black hole of mass 6.4x10^9 M_sun, whose activity is responsible for the…
Discovery of large-scale diffuse radio emission in low-mass galaxy cluster Abell 1931
M. Brüggen, D. Rafferty, A. Bonafede +12
Extended, steep-spectrum radio synchrotron sources are pre-dominantly found in massive galaxy clusters as opposed to groups. LOFAR Two-Metre Sky Survey images have revealed a diffu…
LOFAR imaging of Cygnus A -- Direct detection of a turnover in the hotspot radio spectra
J. P. McKean, L. E. H. Godfrey, S. Vegetti +75
The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termin…
The spectacular cluster chain Abell 781 as observed with LOFAR, GMRT, and XMM-Newton
A. Botteon, T. W. Shimwell, A. Bonafede +20
A number of merging galaxy clusters show the presence of large-scale radio emission associated with the intra-cluster medium (ICM). These synchrotron sources are generally classifi…
The LOFAR Multifrequency Snapshot Sky Survey (MSSS) I. Survey description and first results
G. H. Heald, R. F. Pizzo, E. Orrú +147
We present the Multifrequency Snapshot Sky Survey (MSSS), the first northern-sky LOFAR imaging survey. In this introductory paper, we first describe in detail the motivation and de…
Evidence for the role of proton shell closure in quasi-fission reactions from X-ray fluorescence of mass-identified fragments
M. Morjean, D. J. Hinde, C. Simenel +14
The atomic numbers and the masses of fragments formed in quasi-fission reactions have been simultaneously measured at scission in 48 Ti + 238 U reactions at a laboratory energy of…
The LOFAR radio environment
A. R. Offringa, A. G. de Bruyn, S. Zaroubi +93
Aims: This paper discusses the spectral occupancy for performing radio astronomy with the Low-Frequency Array (LOFAR), with a focus on imaging observations. Methods: We have analys…
The ASKAP/EMU Source Finding Data Challenge
A. M. Hopkins, M. T. Whiting, N. Seymour +31
The Evolutionary Map of the Universe (EMU) is a proposed radio continuum survey of the Southern Hemisphere up to declination +30 deg., with the Australian Square Kilometre Array Pa…
LOFAR discovery of a quiet emission mode in PSR B0823+26
C. Sobey, N. J. Young, J. W. T. Hessels +91
PSR B0823+26, a 0.53-s radio pulsar, displays a host of emission phenomena over timescales of seconds to (at least) hours, including nulling, subpulse drifting, and mode-changing.…
The LOFAR Two-metre Sky Survey - II. First data release
T. W. Shimwell, C. Tasse, M. J. Hardcastle +104
The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120-168MHz survey of the entire northern sky for which observations are now 20% complete. We present…
LOFAR discovery of radio emission in MACSJ0717.53745
A. Bonafede, M. Brüggen, D. Rafferty +16
We present results from LOFAR and GMRT observations of the galaxy cluster MACSJ0717.53745. The cluster is undergoing a violent merger involving at least four sub-clusters, a…
The LABOCA survey of the Extended Chandra Deep Field South: Two modes of star formation in AGN hosts?
D. Lutz, V. Mainieri, D. Rafferty +23
We study the co-existence of star formation and AGN activity in X-ray selected AGN by analyzing stacked 870um submm emission from a deep and wide map of the Extended Chandra Deep F…