A5028585861- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- History and Developments in Astronomy
- Historical Astronomy and Related Studies
- Global Maritime and Colonial Histories
- Biomedical and Engineering Education
- Genetics, Bioinformatics, and Biomedical Research
- Radio Wave Propagation Studies
- Ionosphere and magnetosphere dynamics
- Diversity and Career in Medicine
- Astro and Planetary Science
- Career Development and Diversity
- Neutrino Physics Research
- Medical and Agricultural Research Studies
- Astronomical and nuclear sciences
South African Radio Astronomy Observatory
2013-2024
Astronomical Observatory
2019-2024
University of Antananarivo
2022-2024
University of South Africa
2019
University of Cape Town
2010-2018
We present the discovery and mass measurement of cold, low-mass planet MOA-2009-BLG-266Lb, performed with gravitational microlensing method. This has a mp = 10.4 ± 1.7 M⊕ orbits star M⋆ 0.56 0.09 M☉ at semimajor axis AU an orbital period yrs. The host measurements are enabled by parallax effect, which is seen primarily in light curve distortion due to motion Earth. But analysis also demonstrates capability measure Deep Impact (or EPOXI) spacecraft heliocentric orbit. distance similar...
ABSTRACT We study the nature of faint radio source population detected in MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Early Science data COSMOS field, focusing on properties radio-loud active galactic nuclei (AGNs). Using extensive multiwavelength available we are able to classify 88 per cent 5223 sources field with host galaxy identifications as AGNs (35 cent) or star-forming galaxies (54 cent). select a sample redshifts out z ∼ 6 and luminosities 1020 < L1.4...
We studied bent radio sources within X-ray galaxy groups in the COSMOS and XMM-LSS fields. The data were obtained from MeerKAT International GHz Tiered Extragalactic Explorations release 1 (MIGHTEE-DR1) at 1.2-1.3 GHz, with angular resolutions of 8.9" 5", median noise levels rms_ med ∼ = 3.5 5.5 μJy/beam. Bent active galactic nuclei (AGN) identified through visual inspection. Our analysis included 19 AGN field 17 that lie ($2 200c /M_ ⊙ ≤ 3 $). investigated relationship between their bending...
We report the discovery of two new giant radio galaxies (GRGs) using MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey. Both GRGs were found within a 1 deg^2 region inside COSMOS field. They have redshifts z=0.1656 and z=0.3363 physical sizes 2.4Mpc 2.0Mpc, respectively. Only cores these clearly visible in previous high resolution VLA observations, since diffuse emission lobes was resolved out. However, excellent sensitivity uv coverage telescope allowed this to be...
We study the radio spectral properties of 2,094 star-forming galaxies (SFGs) by combining our early science data from MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey with VLA, GMRT data, and rich ancillary in COSMOS field. These SFGs are selected at VLA 3GHz, their flux densities 1.3GHz 325MHz imaging extracted using "super-deblending" technique. The median index is $\alpha_{\rm 1.3GHz}^{\rm 3GHz}=-0.80\pm0.01$ without significant variation across rest-frame...
Abstract We present deep 1.4 GHz source counts from ∼5 deg2 of the continuum Early Science data release MeerKAT International Gigahertz Tiered Extragalactic Exploration survey down to S1.4GHz ∼15 $\mu$Jy. Using observations over two extragalactic fields (COSMOS and XMM-LSS), we provide a comprehensive investigation into correcting incompleteness raw within understand true underlying count population. use variety simulations that account for: errors in detection characterization, clustering,...
We have established a relation between the brightest super star cluster (SSC) magnitude in galaxy and host formation rate (SFR) for first time near-infrared (NIR). The data come from statistical sample of ∼40 luminous IR galaxies (LIRGs) starbursts utilizing K-band adaptive optics imaging. While expanding observed to longer wavelengths, less affected by extinction effects, it also pushes higher SFRs. we find, MK ∼ −2.6log SFR, is similar that derived previously optical at lower It does not,...
Super star clusters (SSCs) are typically found in interacting galaxies and trace an extreme form of formation. We present a K-band study SSC candidates sample local luminous infrared (LIRGs) using two adaptive optics instruments: the Very Large Telescope's Nasmyth Adaptive Optics System–COude Near Infrared CAmera (NACO) Gemini's ALTtitude conjugate for InfraRed (ALTAIR)/Near Imager Spectrometer (NIRI). In addition to facilitating detections obscured environments, this work introduces studies...
Nuclear starbursts and active galactic nucleus (AGN) activity are the main heating processes in luminous infrared galaxies (LIRGs) their relationship is fundamental to understand galaxy evolution. In this paper, we study star formation AGN of a sample 11 local LIRGs imaged with subarcsecond angular resolution at radio (8.4 GHz) near-infrared (2.2 μm) wavelengths. This allows us characterize central kpc these spatial ≃100 pc. general, find good correlation between near-IR emission, although...
Archival WFC3/UVIS imaging of Arp 299 (NGC 3690E + NGC 3690W) is retrieved to investigate the young massive cluster (YMC) population this ongoing merger. We extract 2182 candidates, including 1323 high confidence photometric sources. Multiband photometry matched with Yggdrasil models estimate age, mass, and extinction each cluster. A Schechter fit truncated mass function results in a characteristic ${\rm M_{*} = 1.6 \times 10^6 M_{\odot}}$. Our confirm that intensely star-forming galaxies...
In addition to the extended main-sequence turnoffs widely found in young and intermediate-age (~ 600 Myr-2 Gyr-old) star clusters, some younger clusters even exhibit split main sequences (MSs). Different stellar rotation rates are proposed account for bifurcated MS pattern, with red blue MSs (rMS bMS) populated by fast slowly rotating stars, respectively. Using photometry from Gaia Early Data Release 3, we report a Galactic open cluster MS, NGC 2422 ( ~ 90 Myr). We exclude possibilities that...
Jets of energetic particles, as seen in FR type-I and type-II sources, ejected from the center Radio-Loud AGN affect sources surrounding intracluster medium/intergalactic medium. Placing constraints on age such is important order to measure jet powers determine effects feedback. To evaluate these using spectral models, we require high-resolution multi-wavelength data. The new sensitive MIGHTEE survey XMM-LSS field along with data Low Frequency Array (LOFAR) Giant Metrewave Radio Telescope...
ABSTRACT In this paper, we combine the Early Science radio continuum data from MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Survey, with optical and near-infrared release cross-matched catalogues. The used in work covers 0.86 deg2 of COSMOS field, reaches a thermal noise 1.7 μJy beam−1 contains 6102 components. We visually inspect cross-match sample Hyper Suprime-Cam (HSC) UltraVISTA surveys. This allows properties active galactic nuclei star-forming populations...
We report the discovery of a remnant radio AGN J1615+5452 in field ELAIS-N1. GMRT continuum observations at 150, 325 and 610 MHz combined with archival data from 1.4 GHz NVSS survey were used to derive spectrum source. At redshift $z \sim$ 0.33, has linear size $\sim$ 100 kpc spectral indices ranging between $\alpha^{1400}_{610} < -1.5$ $\alpha^{325}_{150} = -0.61 \pm 0.12$. While source diffuse emission low frequencies, we do not find evidence core, jets or hotspots 1.4\,GHz VLA $\sim 5$...
Over the past decade, several works have used ratio between total (rest 8−1000 μ m) infrared and radio 1.4 GHz) luminosity in star-forming galaxies ( q IR ), often referred to as infrared-radio correlation (IRRC), calibrate emission a star formation rate (SFR) indicator. Previous studies constrained evolution of with redshift, finding mild but significant decline that is yet be understood. Here, for first time, we function both stellar mass M ⋆ ) starting from an -selected sample > 400...
An analysis of the star cluster population in a low-luminosity early type galaxy, NGC 2328, is presented. The clusters are found tight star-forming nuclear spiral/ring pattern and we also identify bar from structural 2D decomposition. These massive forming very efficiently circum-nuclear environment, they young, possibly all less than 30 Myr age. indicate an azimuthal age gradient, consistent with "pearls-on-a-string" formation scenario suggesting driven gas inflow. mass function has robust...
Abstract Mergers of galaxies are an important mode for galaxy evolution because they serve as efficient trigger powerful starbursts. However, observational studies molecular gas properties during their early stages scarce. We present interferometric CO(2–1) maps two luminous infrared galaxies, NGC 3110 and 232, obtained with the Submillimeter Array ∼1 kpc resolution. While is a spiral interacting minor (14:1 stellar mass) companion, 232 similarly sized object. find that such interactions in...
We present the discovery and follow-up observations of two CCSNe that occurred in luminous infrared galaxy (LIRG), NGC3256. The first, SN2018ec, was discovered using ESO HAWK-I/GRAAL adaptive optics seeing enhancer, classified as a Type Ic with host extinction $A_V=2.1^{+0.3}_{-0.1}$ mag. second, AT2018cux, during course is consistent sub-luminous IIP classification an $A_V=2.1 \pm 0.4$ mag extinction. A third CCSN, PSNJ10275082-4354034 NGC3256, has previously been reported 2014, we...
Abstract We present Atacama Large Millimeter/submillimeter Array observations of multiple 12 CO, 13 and C 18 O lines 2.9 mm 1.3 continuum emission toward the nearby interacting luminous infrared galaxy NGC 3110, supplemented with similar spatial resolution H α , 1.4 GHz continuum, K -band data. estimate typical CO-to-H 2 conversion factor 1.7 M ⊙ (K km s −1 pc ) within disk using local thermal equilibrium-based dust-based column densities, measure 1 kpc scale surface densities star formation...
ABSTRACT In this study we report the spatially resolved, wideband spectral properties of three giant radio galaxies (GRGs) in COSMOS field: MGTC J095959.63+024608.6, J100016.84+015133.0, and J100022.85+031520.4. One these galaxies, J100022.85+031520.4, is reported here for first time, with a projected linear size 1.29 Mpc at redshift 0.1034. Unlike other two, it associated brightest cluster galaxy (BCG), making one few GRGs known to inhabit environments. We examine age distributions using...
In this study we report spatially resolved, wideband spectral properties of three giant radio galaxies (GRGs) in the COSMOS field: MGTC J095959.63+024608.6 , J100016.84+015133.0 and J100022.85+031520.4. One such galaxy J100022.85+031520.4 is reported here for first time with a projected linear size 1.29 Mpc at redshift 0.1034. Unlike other two, it associated brightest cluster (BCG), making one few GRGs known to inhabit environments. We examine age distributions using new MeerKAT UHF-band...
We studied bent radio sources within X-ray galaxy groups in the COSMOS and XMM-LSS fields, using data from MeerKAT International GHz Tiered Extragalactic Explorations release 1 (MIGHTEE-DR1) at 1.2-1.3 (angular resolutions of 8.9" 5"; <rms> ~ 3.5 5.5 uJy/beam). Bent active galactic nuclei (AGN) were identified via visual inspection. Our analysis included 19 AGN field 17 which lie (2x10^13 >= M200c/Msun = 3x10^14). investigated relationship between their bending angle (BA) - formed by jets or...
We study star formation (SF) in very active environments, luminous IR galaxies, which are often interacting. A variety of phenomena detected, such as central starbursts, circumnuclear SF, obscured SNe tracing the history recent massive super clusters, and sites strong off-nuclear SF. All these can be ultimately used to define sequence triggering propagation star-formation interplay with nuclear activity lives gas rich galaxy interactions mergers. In this paper we present analysis...