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Extragalactic Peaked-Spectrum Radio Sources at Low-Frequencies are Young Radio Galaxies
(2022-12-20)
We present a sample of 373 peaked-spectrum (PS) sources with spectral peaks around 150 MHz, selected using a subset of the two LOw Frequency ARray (LOFAR) all-sky surveys, the LOFAR Two Meter Sky Survey and the LOFAR LBA ...
Transient obscuration event captured in NGC 3227 III. Photoionization modeling of the X-ray obscuration event in 2019
(2022-09-12)
Context. A growing number of transient X-ray obscuration events in type I active galactic nuclei suggest that our line of sight to the central engine is not always free. Multiple X-ray obscuration events were reported in ...
"Relic jet activity in “Hanny’s Voorwerp” revealed by the LOFAR Two metre Sky Survey"
(2022-08-01)
We report new observations of 'Hanny's Voorwerp' (hereafter HV) taken from the second data release of the LOFAR Two-metre Sky Survey (LoTSS). HV is a highly-ionized region in the environs of the galaxy IC2497, first ...
Subarcsecond view on the high-redshift blazar GB 1508+5714 by the International LOFAR Telescope
(2022-07-12)
Context. Studies of the most distant active galactic nuclei (AGNs) allow us to test our current understanding of the physics present in radio-jetted AGNs across a range of environments, and probe their interactions with ...
The discovery of a radio galaxy of at least 5 Mpc
(2022-04-01)
Context. Giant radio galaxies (GRGs, or colloquially giants) are the Universes largest structures generated by individual galaxies. They comprise synchrotron-radiating active galactic nucleus ejecta and attain cosmological ...
Sub-arcsecond imaging with the International LOFAR Telescope : I. Foundational calibration strategy and pipeline
(2022-02-28)
The International LOFAR Telescope is an interferometer with stations spread across Europe. With baselines of up to ∼2000 km, LOFAR has the unique capability of achieving sub-arcsecond resolution at frequencies below 200 ...
The resolved jet of 3C 273 at 150 MHz : Sub-arcsecond imaging with the LOFAR international baselines
(2022-02-01)
Context. Since its discovery in 1963, 3C 273 has become one of the most widely studied quasars with investigations spanning the electromagnetic spectrum. While much has therefore been discovered about this historically ...
High-resolution international LOFAR observations of 4C~43.15 -- Spectral ages and injection indices in a high-z radio galaxy
(2022-02-01)
It has long been known that radio sources with the steepest spectra are preferentially associated with the most distant galaxies, the α - z relation, but the reason for this relation is an open question. The spatial ...
Sub-arcsecond imaging with the International LOFAR Telescope. II. Completion of the LOFAR Long-Baseline Calibrator Survey
(2022-02-01)
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, ...
Transient obscuration event captured in NGC~3227 II. Warm absorbers and obscuration events in archival XMM-Newton and NuSTAR observations
(2022-01-14)
The relationship between warm absorber (WA) outflows of active galactic nuclei and nuclear obscuration activities caused by optically thick clouds (obscurers) crossing the line of sight is still unclear. NGC 3227 is a ...