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Now showing items 13132-13151 of 24382
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LOFAR and APERTIF Surveys of the Radio Sky : Probing Shocks and Magnetic Fields in Galaxy Clusters
(2011-12)At very low frequencies, the new pan-European radio telescope LOFAR is opening the last unexplored window of the electromagnetic spectrum for astrophysical studies. The revolutionary APERTIF-phased arrays that are about ... -
LOFAR Deep Fields : Probing a broader population of polarized radio galaxies in ELAIS-N1
(2021-04-07)We present deep polarimetric observations of the European Large Area ISO Survey-North 1 (ELAIS-N1) field using the Low Frequency Array (LOFAR) at 114.9-177.4 MHz. The ELAIS-N1 field is part of the LOFAR Two-metre Sky Survey ... -
LOFAR discovery of a radio halo in the high-redshift galaxy cluster PSZ2 G099.86+58.45
(2019-08-19)In this Letter, we report the discovery of a radio halo in the high-redshift galaxy cluster PSZ2 G099.86+58.45 ($z=0.616$) with the LOw Frequency ARray (LOFAR) at 120-168 MHz. This is one of the most distant radio halos ... -
LOFAR early-time search for coherent radio emission from GRB 180706A
(2019-10-21)The nature of the central engines of gamma-ray bursts (GRBs) and the composition of their relativistic jets are still under debate. If the jets are Poynting flux dominated rather than baryon dominated, a coherent radio ... -
LOFAR facet calibration
(2016-03-07)LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of the low-frequency radio sky. At the same time LOFAR also provides ... -
LOFAR first look at the giant radio galaxy 3C 236
(2019-07-28)We have examined the giant radio galaxy 3C~236 using LOFAR at 143 MHz down to an angular resolution of 7", in combination with observations at higher frequencies. We have used the low frequency data to derive spectral index ... -
LOFAR HBA observations of the Euclid Deep Field North (EDFN)
(2024-03-18)We present the first deep (72 h of observations) radio image of the Euclid Deep Field North (EDFN) obtained with the LOw-Frequency ARray (LOFAR) High Band Antenna (HBA) at 144 MHz. The EDFN is the latest addition to the ... -
LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra
(2016-12-01)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 termination. These processes are responsible for ... -
The LOFAR LBA Sky Survey I. survey description and preliminary data release
(2021-02-17)Context. The LOw Frequency ARray (LOFAR)istheonlyradiotelescopethatispresentlycapableofhigh-sensitivity,high-resolution (i.e. < 1mJybeam−1 and < 1500) observations at ultra-low frequencies(< 100MHz). To utilise these ... -
The LOFAR LBA Sky Survey II. First data release
(2023-05-26)Context. The Low Frequency Array (LOFAR) is the only existing radio interferometer able to observe at ultra-low frequencies (<100 MHz) with high resolution (<15") and high sensitivity (<1 mJy beam-1). To exploit these ... -
The LOFAR LBA Sky Survey: Deep Fields I. The Boötes Field
(2021-11-10)We present the first sub-mJy ($\approx0.7$ mJy beam$^{-1}$) survey to be completed below 100 MHz, which is over an order of magnitude deeper than previously achieved for widefield imaging of any field at these low frequencies. ... -
Lofar low-band antenna observations of the 3C 295 and boötes fields : Source counts and ultra-steep spectrum sources
(2014-10-01)We present Low Frequency Array (LOFAR) Low Band observations of the Boötes and 3C 295 fields. Our images made at 34, 46, and 62 MHz reach noise levels of 12, 8, and 5 mJy beam-1, making them the deepest images ever obtained ... -
A LOFAR mini-survey for low-frequency radio emission from the nearest brown dwarfs
(2016-12-01)We have conducted a mini-survey for low-frequency radio emission from some of the closest brown dwarfs to the Sun with rapid rotation rates: SIMP J013656.5+093347, WISEPC J150649.97+702736.0, and WISEPA J174124.26+255319.5. ... -
LOFAR MSSS: Detection of a low-frequency radio transient in 400 hrs of monitoring of the North Celestial Pole
(2016-03-01)We present the results of a four-month campaign searching for low-frequency radio transients near the North Celestial Pole with the Low-Frequency Array (LOFAR), as part of the Multifrequency Snapshot Sky Survey (MSSS). The ... -
LOFAR MSSS: Discovery of a 2.56 Mpc giant radio galaxy associated with a disturbed galaxy group
(2017-05-01)We report on the discovery in the LOFAR Multifrequency Snapshot Sky Survey (MSSS) of a giant radio galaxy (GRG) with a projected size of $2.56 \pm 0.07$ Mpc projected on the sky. It is associated with the galaxy triplet ... -
LOFAR MSSS: Flattening low-frequency radio continuum spectra of nearby galaxies
(2018-11-07)Aims. The shape of low-frequency radio continuum spectra of normal galaxies is not well understood, the key question being the role of physical processes such as thermal absorption in shaping them. In this work we take ... -
LOFAR MSSS: The Scaling Relation between AGN Cavity Power and Radio Luminosity at Low Radio Frequencies
(2017-09-07)We present a new analysis of the widely used relation between cavity power and radio luminosity in clusters of galaxies with evidence for strong AGN feedback. We study the correlation at low radio frequencies using two new ... -
The LOFAR Multifrequency Snapshot Sky Survey (MSSS) : I. Survey description and first results
(2015-10-01)We present the Multifrequency Snapshot Sky Survey (MSSS), the first northern-sky Low Frequency Array (LOFAR) imaging survey. In this introductory paper, we first describe in detail the motivation and design of the survey. ... -
LOFAR observations of the XMM-LSS field
(2018-11-19)We present observations of the XMM Large-Scale Structure (XMM-LSS) field observed with the LOw Frequency ARray (LOFAR) at 120-168 MHz. Centred at a J2000 declination of $-4.5^{\circ}$, this is a challenging field to observe ... -
A LOFAR prompt search for radio emission accompanying X-ray flares in GRB 210112A
(2023-11-01)The composition of relativistic gamma-ray burst (GRB) jets and their emission mechanisms are still debated, and they could be matter or magnetically dominated. One way to distinguish these mechanisms arises because a ...