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"Sikhosana, Sinenhlanhla P"
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A GMRT Narrowband vs. Wideband Analysis of the ACT−CL J0034.4+0225 Field Selected from the ACTPol Cluster Sample
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.
Journal Article
A Multiwavelength Dynamical State Analysis of ACT-CL J0019.6+0336
In our study, we show a multiwavelength view of ACT-CL J0019.6+0336 (which hosts a radio halo), to investigate the cluster dynamics, morphology, and ICM. We use a combination of XMM-Newton images, Dark Energy Survey (DES) imaging and photometry, SDSS spectroscopic information, and 1.16 GHz MeerKAT data to study the cluster properties. Various X-ray and optical morphology parameters are calculated to investigate the level of disturbance. We find disturbances in two X-ray parameters and the optical density map shows elongated and axisymmetric structures with the main cluster component southeast of the cluster centre and another component northwest of the cluster centre. We also find a BCG offset of ∼950 km/s from the mean velocity of the cluster, and a discrepancy between the SZ mass, X-ray mass, and dynamical mass (MX,500 and MSZ,500 lies >3σ away from Mdyn,500), showing that J0019 is a merging cluster and probably in a post-merging phase.
Journal Article
A Multiwavelength Dynamical State Analysis of ACT-CLJ0019.6+0336
In our study, we show a multiwavelength view of ACT-CL J0019.6+0336 (which hosts aradio halo), to investigate the cluster dynamics, morphology, and ICM. We use a combination ofXMM-Newton images, Dark Energy Survey (DES) imaging and photometry, SDSS spectroscopicinformation, and 1.16 GHz MeerKAT data to study the cluster properties. Various X-ray and opticalmorphology parameters are calculated to investigate the level of disturbance. We find disturbancesin two X-ray parameters and the optical density map shows elongated and axisymmetric structureswith the main cluster component southeast of the cluster centre and another component northwest ofthe cluster centre. We also find a BCG offset of∼950 km/s from the mean velocity of the cluster, anda discrepancy between the SZ mass, X-ray mass, and dynamical mass (MX,500andMSZ,500lies>3σaway fromMdyn,500), showing that J0019 is a merging cluster and probably in a post-merging phase.
Journal Article
The MeerKAT Galaxy Clusters Legacy Survey: star formation in massive clusters at 0.15 < z < 0.35
We investigate dust-unbiased star formation rates (SFR) as a function of the environment in 20 massive clusters (\\(M_{200}>4\\times10^{14} {\\rm M}_{\\odot}\\)) between \\(0.15
Paper
A GMRT Narrowband vs. Wideband Analysis of the ACT-CLJ0034.4+0225 Field Selected from the ACTPol Cluster Sample
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.
Paper
A Multiwavelength Dynamical State Analysis of ACT-CL J0019.6+0336
In our study, we show a multiwavelength view of ACT-CL J0019.6+0336 (which hosts a radio halo), to investigate the cluster dynamics, morphology, and ICM. We use a combination of XMM-Newton images, Dark Energy Survey (DES) imaging and photometry, SDSS spectroscopic information, and 1.16 GHz MeerKAT data to study the cluster properties. Various X-ray and optical morphology parameters are calculated to investigate the level of disturbance. We find disturbances in two X-ray parameters and the optical density map shows elongated and axisymmetric structures with the main cluster component southeast of the cluster centre and another component northwest of the cluster centre. We also find a BCG offset of \\(\\sim\\)950 km/s from the mean velocity of the cluster, and a discrepancy between the SZ mass, X-ray mass, and dynamical mass (\\(M_{X,500}\\) and \\(M_{SZ,500}\\) lies >3 \\(\\sigma\\) away from \\(M_{\\rm{dyn},500}\\)), showing that J0019 is a merging cluster and probably in a post-merging phase.
Paper
A Multiwavelength Dynamical State Analysis of ACT-CLJ0019.6+0336
In our study, we show a multiwavelength view of ACT-CL J0019.6+0336 (which hosts aradio halo), to investigate the cluster dynamics, morphology, and ICM. We use a combination ofXMM-Newton images, Dark Energy Survey (DES) imaging and photometry, SDSS spectroscopicinformation, and 1.16 GHz MeerKAT data to study the cluster properties. Various X-ray and opticalmorphology parameters are calculated to investigate the level of disturbance. We find disturbancesin two X-ray parameters and the optical density map shows elongated and axisymmetric structureswith the main cluster component southeast of the cluster centre and another component northwest ofthe cluster centre. We also find a BCG offset of∼950 km/s from the mean velocity of the cluster, anda discrepancy between the SZ mass, X-ray mass, and dynamical mass (MX,500andMSZ,500lies 3σaway fromMdyn,500), showing that J0019 is a merging cluster and probably in a post-merging phase.
Web Resource
MERGHERS: An SZ-selected cluster survey with MeerKAT
The MeerKAT telescope will be one of the most sensitive radio arrays in the pre-SKA era. Here we discuss a low-frequency SZ-selected cluster survey with MeerKAT, the MeerKAT Extended Relics, Giant Halos, and Extragalactic Radio Sources (MERGHERS) survey. The primary goal of this survey is to detect faint signatures of diffuse cluster emission, specifically radio halos and relics. SZ-selected cluster samples offer a homogeneous, mass-limited set of targets out to higher redshift than X-ray samples. MeerKAT is sensitive enough to detect diffuse radio emission at the faint levels expected in low-mass and high-redshift clusters, thereby enabling radio halo and relic formation theories to be tested with a larger statistical sample over a significantly expanded phase space. Complementary multiwavelength follow-up observations will provide a more complete picture of any clusters found to host diffuse emission, thereby enhancing the scientific return of the MERGHERS survey.
Paper