A5075829807- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Cosmology and Gravitation Theories
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Dark Matter and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Gyrotron and Vacuum Electronics Research
- Radio, Podcasts, and Digital Media
- Particle Accelerators and Free-Electron Lasers
- CCD and CMOS Imaging Sensors
- Superconducting and THz Device Technology
University of KwaZulu-Natal
2019-2025
MeerKAT’s large number (64) of 13.5 m diameter antennas, spanning 8 km with a densely packed 1 core, create powerful instrument for wide-area surveys, high sensitivity over wide range angular scales. The MeerKAT Galaxy Cluster Legacy Survey (MGCLS) is programme long-track L -band (900−1670 MHz) observations 115 galaxy clusters, observed ∼6−10 h each in full polarisation. first legacy product data release (DR1), made available this paper, includes the visibilities, basic image cubes at ∼8″...
Abstract The MeerKAT Absorption Line Survey (MALS) has observed 391 telescope pointings at the L band (900–1670 MHz) δ ≲ +20°. We present radio continuum images and a catalog of 495,325 (240,321) sources detected signal-to-noise ratio (S/N) > 5 over an area 2289 deg 2 (1132 ) 1006 MHz (1381 MHz). Every MALS pointing contains central bright source ( S 1 GHz ≳ 0.2 Jy). median spatial resolution is 12″ (8″). rms noise away from center 25 μ Jy beam −1 (22 within ∼15% achievable theoretical...
The Shapley Supercluster ($\langle z \rangle\approx0.048$) contains several tens of gravitationally bound clusters and groups, making it is an ideal subject for radio studies cluster mergers. We used new high sensitivity observations to investigate the less energetic events mass assembly in from supercluster down galactic scales. created total intensity images full region between A 3558 3562, $\sim 230$ 1650$ MHz, using ASKAP, MeerKAT GMRT, with sensitivities ranging 6$ 100$ $\mu$Jy...
ABSTRACT Multiwavelength studies of galaxy clusters are crucial for understanding the complex interconnection thermal and non-thermal constituents these massive structures uncovering physical processes involved in their formation evolution. Here, we report a multiwavelength assessment cluster A384, which was previously reported to host radio halo with 660 kpc size at MeerKAT 1.28 GHz. The is slightly offset from centre. Our upgraded Giant Metrewave Radio Telescope observation reveals that...
Using a MeerKAT observation of the galaxy cluster A3562 (a member Shapley Supercluster), we have discovered narrow, long and straight, very faint radio filament, which branches out at straight angle from tail located in projection near core cluster. The filament spans 200 kpc aligns with sloshing cold front seen X-rays, staying inside projection. spectral index along appears uniform (within large uncertainties) $\alpha\simeq -1.5$. We propose that is outside front, but dips its under front....
We present the second data release of MeerKAT Absorption Line Survey (MALS), consisting wideband continuum catalogues 391 pointings observed at L~band. The full catalogue covers 4344 deg$^2$ sky, reaches a depth 10 $\mu$Jy beam$^{-1}$, and contains 971,980 sources. With its balance between survey sky coverage, MALS DR2 five orders magnitude flux density, presenting robust view extragalactic radio source population down to 200 $\mu$Jy. Using this catalogue, we perform measurement cosmic...
The MeerKAT Exploration of Relics, Giant Halos, and Extragalactic Radio Sources (MERGHERS) survey is a planned project to study large statistical sample galaxy clusters with the observatory. Here we present results 16--hour pilot project, observed in response 2019 Shared Risk proposal call, test feasibility using for cluster short (0.2--2.1\,hour) integration times. focuses on 1.28\,GHz observations 13 massive, low-to-intermediate redshift ($0.22 < z 0.65$) from...
We aim to carry out a radio study of the SoUthern Cluster sCale Extended Source Survey (SUCCESS) sample consisting twenty massive (M$_{500} > 5\times10^{14}$ M$_{\odot}$), nearby (redshift $<0.3$) and southern ($-50^{\circ} < \delta -30^\circ$) galaxy clusters detected by Planck satellite South Pole Telescope. Here we report targeted GMRT observations (325/610 MHz) for sub-sample nine clusters. also use first data release MeerKAT Galaxy Legacy (1283 five these The properties mini-halo in RXC...
The Bullet cluster (1E 0657-55.8) is a massive merging system at redshift $z$=0.296, known to host powerful radio halo and relic. Here we present high fidelity MeerKAT L-band (0.9-1.7 GHz) observations of the cluster, in which trace larger extent both relic comparison previous studies. size recovered 1.6 Mpc $\times$ 1.3 largest linear ~988 kpc. We detect new decrement feature on southern outskirts emission, where region appears have lower surface brightness its surroundings. extension...
The number counts of homogeneous samples radio sources are a tried and true method probing the large scale structure Universe, as most outside galactic plane at cosmological distances. As such they expected to trace cosmic dipole, an anisotropy analogous dipole seen in microwave background (CMB). Results have shown that although matches direction CMB it has significantly larger amplitude. This result challenges our assumption Universe being isotropic, which can repercussions for current...
We present the first detailed radio study of galaxy cluster XMMXCS J2215.9-1738 at $z$ = 1.46 using MeerKAT $L$-band (1.3 GHz) observations. combine our observation with archival optical and infrared data to investigate star formation AGN population within $R_{200}$ ($R $ 0.8 Mpc) centre. Using three selection criteria; luminosity, far-infrared ratio ($q_{\rm{IR}}$) mid-infrared colour, we distinguish galaxies emission predominantly powered by from that AGNs. selected 24 members...
ABSTRACT We present the first detailed radio study of galaxy cluster XMMXCS J2215.9−1738 at z = 1.46 using MeerKAT L-band (1.3 GHz) observations. combine our observation with archival optical and infrared data to investigate star formation active galactic nucleus (AGN) population within $R_{200}$ ($R =$ 0.8 Mpc) centre. Using three selection criteria; luminosity, far-infrared ratio ($q_{\rm {IR}}$), mid-infrared colour, we distinguish galaxies emission predominantly powered by from that...
Abstract We present results of an optical spectroscopic survey using SALT and the Nordic Optical Telescope to build a Wide-field Infrared Survey Explorer mid-infrared color-based, dust-unbiased sample powerful radio-bright (>200 mJy at 1.4 GHz) active galactic nuclei (AGN) for MeerKAT Absorption Line (MALS). Our has 250 AGN (median z = 1.8) showing emission lines, 26 with no 27 without counterparts. Overall, our is fainter (Δ i 0.6 mag) redder (Δ( g − ) 0.2 than radio-selected quasars,...
Abstract We present details of the Automated Radio Telescope Imaging Pipeline ( ARTIP ) and results a sensitive blind search for H i OH absorbers at z < 0.4 0.7, respectively. is written in Python 3.6, extensively uses Common Astronomy Software Application tools tasks, designed to enable geographically distributed MeerKAT Absorption Line Survey (MALS) team collaboratively process large volumes radio interferometric data. apply it first MALS data set obtained using 64-dish telescope 32 K...
Abstract We investigate dust-unbiased star formation rates (SFRs) as a function of the environment in 20 massive clusters ($M_{200}\gt 4\times 10^{14}\, {\rm M}_{\odot }$) between 0.15 &lt; $z$ 0.35 using radio luminosities (L1.4GHz) from recently released MeerKAT Galaxy Cluster Legacy Survey catalogue. use optical data Dark Energy Camera to estimate photo-$z$s and assign cluster membership. observe steady decline fraction (fSF) star-forming galaxies 2R200 centres our full sample, but...
ABSTRACT The transformation and evolution of a galaxy is strongly influenced by interactions with its environment. Neutral hydrogen (H i) an excellent way to trace these interactions. Here, we present H i observations the spiral NGC 895, which was previously thought be isolated. High-sensitivity from MeerKAT large survey project MIGHTEE reveal possible interaction features, such as extended arms two newly discovered companions, that drive us change narrative it isolated galaxy. We combine...
In our study, we show a multiwavelength view of ACT-CL J0019.6+0336 (which hosts radio halo), to investigate the cluster dynamics, morphology, and ICM. We use combination XMM-Newton images, Dark Energy Survey (DES) imaging photometry, SDSS spectroscopic information, 1.16 GHz MeerKAT data study properties. Various X-ray optical morphology parameters are calculated level disturbance. find disturbances in two density map shows elongated axisymmetric structures with main component southeast...
In the current paradigm, high redshift radio halos are expected to be scarce due inverse Compton energy losses and dimming, which cause them intrinsically faint. This low occurrence fraction is predicted by cosmic ray electron turbulent re-acceleration models. To date, only a handful of have been detected at z > 0.8. We report MeerKAT detection halo hosted galaxy cluster ACT-CL J0329.2-2330 = 1.23, making it highest thus far. Using L-band UHF-band observations, we derive spectral index...
Multiwavelength studies of galaxy clusters are crucial for understanding the complex interconnection thermal and non-thermal constituents these massive structures uncovering physical processes involved in their formation evolution. Here, we report a multiwavelength assessment cluster A384, which was previously reported to host radio halo with 660 kpc size at MeerKAT 1.28 GHz. The is slightly offset from centre. Our uGMRT observation reveals that extends up 690 407 MHz nonuniform spectral...
Abstract ACT-CL J0034.4+0225 is a previously unrecognized merging galaxy cluster at z = 0.38588 ± 0.00068. Our primary evidence provided by 21 ks Chandra image that shows two surface brightness peaks separated ∼49″ (259 kpc) surrounded an extended gas distribution. Each peak contains brightest galaxy, offset from the peak. We collect new South African Large Telescope optical spectra that, when augmented archival data, yield redshifts for BGCs and 58 other members. Archival Giant Metrewave...
Low frequency radio observations of galaxy clusters are a useful probe the non-thermal intracluster medium (ICM), through diffuse emission such as halos and relics. Current formation theories cannot fully account for some observed properties this emission. In study, we focus on development interferometric techniques extracting extended, faint emissions in presence bright, compact sources wide-field broadband continuum imaging data. We aim to apply these study halos, relics mini-halos using...
The transformation and evolution of a galaxy is strongly influenced by interactions with its environment. Neutral hydrogen (\HI) an excellent way to trace these interactions. Here, we present \HI\ observations the spiral NGC~895, which was previously thought be isolated. High-sensitivity from MeerKAT large survey project MIGHTEE reveal possible interaction features, such as extended arms, two newly discovered companions, that drive us change narrative it isolated galaxy. We combine deep...
The MeerKAT Absorption Line Survey (MALS) has observed 391 telescope pointings at L-band (900 - 1670 MHz) $\delta\lesssim$ $+20\deg$. We present radio continuum images and a catalog of 495,325 (240,321) sources detected signal-to-noise ratio (SNR) $>$5 over an area 2289 deg$^2$ (1132 deg$^2$) 1006 MHz (1381 MHz). Every MALS pointing contains central bright source ($S_{1\,\mathrm{GHz}} \gtrsim 0.2$ Jy). median spatial resolution is $12^{\prime\prime}$ ($8^{\prime\prime}$). rms noise away from...