Conveners
Science: EoR
- There are no conveners in this block
Science: SHI
- There are no conveners in this block
Science: GEG
- There are no conveners in this block
Science: Transients
- There are no conveners in this block
Science: Transients
- There are no conveners in this block
Science: VCS
- There are no conveners in this block
Science: Phase III Discussion
- Melanie Johnston-Hollitt (ICRAR/Curtin)
Detecting and characterising the neutral hydrogen 21cm signal from the first billion years of the Universe remains a primary goal of most low-frequency radio telescopes. The structure and evolution of this signal encodes key information about the formation of structure in the early Universe, in the period termed the Epoch of Reionisation. In this talk, I will describe recent results from the...
Calibration approaches for 21 cm cosmology experiments can be broadly categorized as either ‘sky-based,’ relying on an extremely accurate model of astronomical foreground emission, or ‘redundant,’ requiring a precisely regular array with near-identical antenna response patterns. We show that sky-based and redundant calibration can be unified into a highly general and physically motivated...
Understanding the beam shapes of the Murchison Widefield Array(MWA) tiles is particularly important to studies of faint structure such as extragalactic mapping and the Epoch of Reionization (EoR). As teams around the globe improve analysis techniques and their understanding of instrumental effects, the 21cm power spectrum detection of EoR structure is in sight. At this stage,...
In this talk I'll introduce WODEN*, an MWA specific simulator capable of simulating point source, Gaussian, and shapelet sky models. The code is designed to run on GPUs, to allow simulations with order > 10$^6$ components to run in good time. The over-arching goal of this code is to propagate a full EoR light cone simulation + foregrounds through to data products that can be ingested by our...
The past year has been an eventful one for the SHI Collaboration. Our long term investment in developing the tools and techniques have begun to yield interesting results. The MWA solar group has now established itself globally as one of the leading solar radio physics groups. With dynamic ranges (DR) exceeding 100,000, the MWA solar images now represent the state-of-the-art at metrewaves by a...
In this talk we will explore the relevance of nanoflare based models for heating the quiet sun corona. Using metrewave data from the Murchison Widefield Array, we present the first successful detection of impulsive emissions down to flux densities of ~1mSFU, about two orders of magnitude weaker than earlier attempts. These impulsive emissions have durations less than about a 1s and are present...
The Sun is a vast laboratory of plasma. In solar corona, the plasma rests in the heterogeneous magnetic field networks, which are rooted in the photosphere. Besides, solar plasma in corona is also dynamic, which is most drastically seen during a solar flare. Overall, solar emission is inherently variable in space and time. The MWA solar observations have captured this variability and produced...
Absolute flux density calibration of the Sun is a challenging problem. Due to the very large field of view and high primary beam sidelobes of MWA, the measured flux density of a typical calibrator is significantly contaminated by solar contribution while the Sun is above the horizon. Hence calibrators are observed before sunrise and after sunset, resulting in a significant time separation ...
The MWA is a low-frequency radio telescope that can probe galaxy clusters on Mega-parsec scales via their non-thermal, diffuse synchrotron emission. Using the Galactic and Extragalactic All-sky MWA (GLEAM) survey (Wayth et al. 2015, Hurley-Walker et al. 2017), we have identified over 500 candidate sources of such emission, increasing from the known ~ 100 examples. These sources, halos and...
The jets produced by accretion onto super-massive black holes inflate into cocoons of shocked plasma (radio galaxies). While a majority of such sources have an active galactic nucleus, the central activity in a small fraction of radio galaxies switches off, giving rise to a dying radio galaxy. This talk presents the results of Quici et al. (in prep), which identifies a complete sample of...
Historically, the low-frequency linearly-polarised radio source population has remained largely unexplored. However, the advent of new instrumentation in the SKA Pathfinder and Precursor era, plus recent advances in supercomputing and data processing techniques, have enabled a renaissance in this field.
In this talk, I will present the results of the POlarised GLEAM Survey (POGS), our...
Radio-loud active galactic nuclei (AGN) feature heavily in our understanding of galaxy evolution. However, when it comes to studying their properties as a function of redshift and/or environment, the most-detailed studies tend to be limited by small-number statistics. In this talk, we will give an update on this new sample of 1,863 of the brightest radio-sources in the southern sky (Dec. < 30...
Cosmic rays are the most extreme particles in the Universe and are detectable on Earth. The radio emission produced by cosmic rays when they interact with the Earth’s atmosphere is an excellent tracer of their properties. The low radio frequency interference environment of the Murchison Widefield Array (MWA) makes this instrument ideal for detecting and measuring this radio emission and...
I will present an overview of the various scientific and technical development activities around the VCS (pulsar) science, with particular emphasis on the progress being made with the SMART pulsar survey, and the new projects that are being initiated around this initiative.
The emission mechanism of radio pulsars is a long-standing and important open question in astrophysics. Although average pulse profiles can reveal global properties of pulsar magnetospheres, a successful theory emission mechanism must be able to explain the wide variety of phenomena seen at the single pulse level. We have leveraged the recent developments in the MWA-VCS software pipeline to...
With the ability to reconstruct high-time resolution voltage time series at microsecond ($\sim 0.78 \mu$s) time resolution and perform phase-coherent de-dispersion, it has become possible to obtain high-fidelity detections of millisecond pulsars (MSPs) with the MWA. In combination with the large frequency lever arm provided by the MWA this allows measuring pulsar dispersion measures (DMs) at...
