scholarly journals A very brief description of LOFAR – the Low Frequency Array

2006 ◽  
Vol 2 (14) ◽  
pp. 386-387 ◽  
Author(s):  
Heino D. Falcke ◽  
Michiel P. van Haarlem ◽  
A. Ger de Bruyn ◽  
Robert Braun ◽  
Huub J.A. Röttgering ◽  
...  
Keyword(s):  
Low Frequency ◽  
Neutral Hydrogen ◽  
High Energy ◽  
Short Term ◽  
First Stars ◽  
High Energy Cosmic Rays ◽  
Radio Detection ◽  
First Time ◽  
X Ray Binaries ◽  
The Universe

AbstractLOFAR (Low Frequency Array) is an innovative radio telescope optimized for the frequency range 30–240 MHz. The telescope is realized as a phased aperture array without any moving parts. Digital beam forming allows the telescope to point to any part of the sky within a second. Transient buffering makes retrospective imaging of explosive short-term events possible. The scientific focus of LOFAR will initially be on four key science projects (KSPs): (i) Detection of the formation of the very first stars and galaxies in the universe during the so-called epoch of reionization by measuring the power spectrum of the neutral hydrogen 21-cm line (Shaver et al. 1999) on the ∼ 5′ scale; (ii) Low-frequency surveys of the sky with of order 108 expected new sources; (iii) All-sky monitoring and detection of transient radio sources such as γ-ray bursts, X-ray binaries, and exo-planets (Farrell et al. 2004); and (iv) Radio detection of ultra-high energy cosmic rays and neutrinos (Falcke & Gorham 2003) allowing for the first time access to particles beyond 1021 eV (Scholten et al. 2006). Apart from the KSPs open access for smaller projects is also planned. Here we give a brief description of the telescope.

scholarly journals Fundamental differences in the radio properties of red and blue quasars: insight from the LOFAR Two-metre Sky Survey (LoTSS)

2020 ◽  
Vol 494 (3) ◽  
pp. 3061-3079 ◽  
Author(s):  
D J Rosario ◽  
V A Fawcett ◽  
L Klindt ◽  
D M Alexander ◽  
L K Morabito ◽  
...  
Keyword(s):  
Star Formation ◽  
Control Sample ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
Stellar Objects ◽  
Radio Detection ◽  
Sky Survey ◽  
Quasi Stellar Objects ◽  
First Time

ABSTRACT Red quasi-stellar objects (QSOs) are a subset of the luminous end of the cosmic population of active galactic nuclei (AGNs), most of which are reddened by intervening dust along the line of sight towards their central engines. In recent work from our team, we developed a systematic technique to select red QSOs from the Sloan Digital Sky Survey, and demonstrated that they have distinctive radio properties using the Faint Images of the Radio Sky at Twenty centimetres radio survey. Here we expand our study using low-frequency radio data from the LOFAR Two-metre Sky Survey (LoTSS). With the improvement in depth that LoTSS offers, we confirm key results: Compared to a control sample of normal ‘blue’ QSOs matched in redshift and accretion power, red QSOs have a higher radio detection rate and a higher incidence of compact radio morphologies. For the first time, we also demonstrate that these differences arise primarily in sources of intermediate radio loudness: Radio-intermediate red QSOs are × 3 more common than typical QSOs, but the excess diminishes among the most radio-loud systems and the most radio-quiet systems in our study. We develop Monte Carlo simulations to explore whether differences in star formation could explain these results, and conclude that, while star formation is an important source of low-frequency emission among radio-quiet QSOs, a population of AGN-driven compact radio sources is the most likely cause for the distinct low-frequency radio properties of red QSOs. Our study substantiates the conclusion that fundamental differences must exist between the red and normal blue QSO populations.

scholarly journals Prospects for radio detection of ultra-high energy cosmic rays and neutrinos

2004 ◽  
Vol 48 (11-12) ◽  
pp. 1487-1510 ◽  
Author(s):  
H. Falcke ◽  
P. Gorham ◽  
R.J. Protheroe
Keyword(s):  
Cosmic Rays ◽  
High Energy ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
Radio Detection

scholarly journals CODALEMA: A COSMIC RAY AIR SHOWER RADIO DETECTION EXPERIMENT

2006 ◽  
Vol 21 (supp01) ◽  
pp. 192-196 ◽  
Author(s):  
D. ARDOUIN ◽  
A. BELLETOILE ◽  
D. CHARRIER ◽  
R. DALLIER ◽  
L. DENIS ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
Air Showers ◽  
Detection Experiment ◽  
Transient Signals ◽  
High Energy Cosmic Rays ◽  
Air Shower ◽  
Radio Detection

The CODALEMA experimental device currently detects and characterizes the radio contribution of cosmic ray air showers : arrival directions and electric field topologies of radio transient signals associated to cosmic rays are extracted from the antenna signals. The measured rate, about 1 event per day, corresponds to an energy threshold around 5.1016eV. These results allow to determine the perspectives offered by the present experimental design for radiodetection of Ultra High Energy Cosmic Rays at a larger scale.

scholarly journals CHASING THE GZK WITH HiRes

2003 ◽  
Vol 18 (18) ◽  
pp. 1235-1245 ◽  
Author(s):  
DOUGLAS R. BERGMAN
Keyword(s):  
Energy Spectrum ◽  
Cosmic Rays ◽  
Energy Loss ◽  
High Energy ◽  
Cosmological Evolution ◽  
Similar Distribution ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
Luminous Matter ◽  
The Universe

The HiRes collaboration has recently announced preliminary measurements of the energy spectrum of ultra-high energy cosmic rays (UHECR), as seen in monocular analyses from each of the two HiRes sites. This spectrum is consistent with the existence of the GZK cutoff, as well other aspects of the energy loss processes that cause the GZK cutoff. Based on the analytic energy loss formalism of Berezinsky et al., the HiRes spectra favor a distribution of extragalactic sources that has a similar distribution to that of luminous matter in the universe, both in its local over-density and in its cosmological evolution.

scholarly journals The Pierre Auger Observatory: Studying the Highest Energy Frontier

2019 ◽  
Vol 64 (7) ◽  
pp. 646
Author(s):  
I. Valiño
Keyword(s):  
Cosmic Rays ◽  
High Energy ◽  
Pierre Auger Observatory ◽  
Quality Data ◽  
Ultra High Energy ◽  
High Quality ◽  
High Quality Data ◽  
High Energy Cosmic Rays ◽  
Energy Frontier ◽  
The Universe

We highlight the main results obtained by the Pierre Auger Collaboration in its quest to unveil the mysteries associated with the nature and origin of the ultra-high energy cosmic rays, the highest-energy particles in the Universe. The observatory has steadily produced high-quality data for more than 15 years, which have already led to a number of major breakthroughs in the field contributing to the advance of our understanding of these extremely energetic particles. The interpretation of our measurements so far opens new questions which will be addressed by the on-going upgrade of the Pierre Auger Observatory.

scholarly journals Air Shower Detection by Arrays of Radio Antennas

2019 ◽  
Vol 208 ◽  
pp. 15001
Author(s):  
Frank G. Schröder
Keyword(s):  
Antenna Arrays ◽  
Standard Technique ◽  
Cosmic Ray ◽  
High Energy ◽  
Nucl Phys ◽  
Mass Composition ◽  
Atmospheric Particle ◽  
High Energy Cosmic Rays ◽  
Radio Detection ◽  
Shower Maximum

Antenna arrays are beginning to make important contributions to high energy astroparticle physics supported by recent progress in the radio technique for air showers. This article provides an update to my more extensive review published in Prog. Part. Nucl. Phys. 93 (2017) 1. It focuses on current and planned radio arrays for atmospheric particle cascades, and briefly references to a number of evolving prototype experiments in other media, such as ice. While becoming a standard technique for cosmic-ray nuclei today, in future radio detection may drive the field for all type of primary messengers at PeV and EeV energies, including photons and neutrinos. In cosmic-ray physics accuracy becomes increasingly important in addition to high statistics. Various antenna arrays have demonstrated that they can compete in accuracy for the arrival direction, energy and position of the shower maximum with traditional techniques. The combination of antennas and particles detectors in one array is a straightforward way to push the total accuracy for high-energy cosmic rays for low additional cost. In particular the combination of radio and muon detectors will not only enhance the accuracy for the cosmic-ray mass composition, but also increase the gamma-hadron separation and facilitate the search for PeV and EeV photons. Finally, the radio technique can be scaled to large areas providing the huge apertures needed for ultra-high-energy neutrino astronomy.

scholarly journals Radio detection of extensive air showers

2019 ◽  
Vol 216 ◽  
pp. 01003
Author(s):  
Jörg R. Hörandel
Keyword(s):  
Cosmic Rays ◽  
High Energy ◽  
Extensive Air Showers ◽  
Air Showers ◽  
High Energy Cosmic Rays ◽  
Future Developments ◽  
Radio Detection

Radio detection of extensive air showers is a flourish technique, attracting more and more interest to investigate the properties of high-energy cosmic rays. Past, present, and future developments are reviewed.

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