Low Frequency Radio Observations of Galaxy Clusters and Groups

2018 ◽  
Author(s):  
Thérèse Cantwell
Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 117
Author(s):  
Sinenhlanhla P. Sikhosana ◽  
Kenda Knowles ◽  
C. H. Ishwara-Chandra ◽  
Matt Hilton ◽  
Kavilan Moodley ◽  
...  

Low frequency radio observations of galaxy clusters are a useful probe of the non-thermal intracluster medium (ICM), through observations of diffuse radio emission such as radio halos and relics. Current formation theories cannot fully account for some of the observed properties of this emission. In this study, we focus on the development of interferometric techniques for extracting extended, faint diffuse emissions in the presence of bright, compact sources in wide-field and broadband continuum imaging data. We aim to apply these techniques to the study of radio halos, relics and radio mini-halos using a uniformly selected and complete sample of galaxy clusters selected via the Sunyaev-Zel’dovich (SZ) effect by the Atacama Cosmology Telescope (ACT) project, and its polarimetric extension (ACTPol). We use the upgraded Giant Metrewave Radio Telescope (uGMRT) for targeted radio observations of a sample of 40 clusters. We present an overview of our sample, confirm the detection of a radio halo in ACT−CL J0034.4+0225, and compare the narrowband and wideband analysis results for this cluster. Due to the complexity of the ACT−CL J0034.4+0225 field, we use three pipelines to process the wideband data. We conclude that the experimental spam wideband pipeline produces the best results for this particular field. However, due to the severe artefacts in the field, further analysis is required to improve the image quality.


2006 ◽  
Vol 2 (14) ◽  
pp. 374-375
Author(s):  
Gianfranco Brunetti

AbstractThe particle reaceleration model is one of the most promising possibilities to explain the Mpc-scale diffuse radio emission detected in a number of galaxy clusters. Ongoing and future radio observations at low frequencies may help in constraining and testing this model.


Author(s):  
Poonam Chandra ◽  
A. J. Nayana ◽  
Claes-Ingvar Bjornsson ◽  
Peter Lundqvist ◽  
Alak K. Ray

2005 ◽  
Vol 5 (S1) ◽  
pp. 87-92 ◽  
Author(s):  
C H Ishwara-Chandra ◽  
A Pramesh Rao ◽  
Mamta Pandey ◽  
R K Manchanda ◽  
Philippe Durouchoux

2020 ◽  
Vol 09 (04) ◽  
pp. 2050019
Author(s):  
H. C. Chiang ◽  
T. Dyson ◽  
E. Egan ◽  
S. Eyono ◽  
N. Ghazi ◽  
...  

Measurements of redshifted 21[Formula: see text]cm emission of neutral hydrogen at [Formula: see text][Formula: see text]MHz have the potential to probe the cosmic “dark ages,” a period of the universe’s history that remains unobserved to date. Observations at these frequencies are exceptionally challenging because of bright Galactic foregrounds, ionospheric contamination, and terrestrial radio-frequency interference. Very few sky maps exist at [Formula: see text][Formula: see text]MHz, and most have modest resolution. We introduce the Array of Long Baseline Antennas for Taking Radio Observations from the Sub-Antarctic (ALBATROS), a new experiment that aims to image low-frequency Galactic emission with an order-of-magnitude improvement in resolution over existing data. The ALBATROS array will consist of antenna stations that operate autonomously, each recording baseband data that will be interferometrically combined offline. The array will be installed on Marion Island and will ultimately comprise 10 stations, with an operating frequency range of 1.2–125[Formula: see text]MHz and maximum baseline lengths of [Formula: see text][Formula: see text]km. We present the ALBATROS instrument design and discuss pathfinder observations that were taken from Marion Island during 2018–2019.


2010 ◽  
Vol 723 (1) ◽  
pp. 620-633 ◽  
Author(s):  
Jingying Wang ◽  
Haiguang Xu ◽  
Junhua Gu ◽  
Tao An ◽  
Haijuan Cui ◽  
...  

2020 ◽  
Author(s):  
Alain Lecacheux ◽  
Stuart D. Bale ◽  
Milan Maksimovic ◽  
Marc Pulupa

<p>The FIELDS/RFS experiment aboard the Parker Solar Probe spacecraft, in orbit around the Sun, is able to detect and remotely study low frequency radio emissions from Jupiter. Accurate measurements of the intensity and polarisation of those emissions (mainly the HOM/DAM components) were obtained throughout years 2018 and 2019. They are compared to similar ones, obtained 20 years ago, during Cassini’s remote flyby of Jupiter. A particular emphasis is brought on the so-called “attenuation bands” phenomenon, - a well-defined intensity extinction/enhancement feature modulating the HOM dynamic spectrum -, which likely results from the radiation propagating to the observer through some permanent or long lived plasma structure (not firmly identified so far) lying in the rotating Jovian inner magnetosphere.</p>


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