Volume 651, July 2021
|Number of page(s)||32|
|Section||Cosmology (including clusters of galaxies)|
|Published online||29 July 2021|
LOFAR observations of galaxy clusters in HETDEX
Extraction and self-calibration of individual LOFAR targets
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
2 ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
3 INAF-Istituto di Radioastronomia, Via Gobetti 101, 40129 Bologna, Italy
4 University of Hamburg, Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
6 Dipartimento di Fisica e Astronomia, Università di Bologna, Via P. Gobetti 93/2, 40129 Bologna, Italy
7 INAF-IASF Milano, Via A. Corti 12, 20133 Milano, Italy
8 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
9 Thüringer Landessternwarte, Sternwarte 5, 07778 Tautenburg, Germany
10 GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
11 Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa
12 USN, Observatoire de Paris, CNRS, PSL, UO, Nançay, France
13 Curtin Institute of Radio Astronomy, 1 Turner Avenue, Technology Park, Bentley, WA 6102, Australia
Accepted: 21 April 2021
Diffuse cluster radio sources, in the form of radio halos and relics, reveal the presence of cosmic rays and magnetic fields in the intracluster medium (ICM). These cosmic rays are thought to be (re)accelerated through the ICM turbulence and shock waves generated by cluster merger events. Here we characterize the presence of diffuse radio emission in known galaxy clusters in the HETDEX Spring Field, covering 424 deg2. For this, we developed a method to extract individual targets from LOFAR observations processed with the LoTSS DDF-pipeline software. This procedure enables improved calibration as well as the joint imaging and deconvolution of multiple pointings of selected targets. The calibration strategy can also be used for LOFAR low-band antenna and international-baseline observations. The fraction of Planck PSZ2 catalog clusters with any diffuse radio emission apparently associated with the ICM is 73 ± 17%. We detect a total of ten radio halos and twelve candidate halos in the HETDEX Spring Field. Of these ten radio halos, four are new discoveries, two of which are located in PSZ2 clusters. Five clusters host radio relics, two of which are new discoveries. The fraction of radio halos in Planck PSZ2 clusters is 31 ± 11%, or 62 ± 15% when including the candidate radio halos. Based on these numbers, we expect that there will be at least 183 ± 65 radio halos found in the LoTSS survey in PSZ2 clusters, in agreement with past predictions. The integrated flux densities for the radio halos were computed by fitting exponential models to the radio images. From these flux densities, we determine the cluster mass (M500) and Compton Y parameter (Y500) 150 MHz radio power (P150 MHz) scaling relations for Planck PSZ2-detected radio halos. Using bivariate correlated errors and intrinsic scatter orthogonal regression, we find slopes of 6.13 ± 1.11 and 3.32 ± 0.65 for the M500–P150 MHz and M500–P150 MHz relations, respectively. These values are consistent with the results of previous works.
Key words: galaxies: clusters: general / galaxies: clusters: intracluster medium / large-scale structure of Universe / radiation mechanisms: non-thermal / X-rays: galaxies: clusters
© ESO 2021
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.