CTA Status

• Gavin Rowell (School of Physical Sciences, University of Adelaide)

I will present an update on the status of CTA, an overview Australia's involvements in CTA, and future funding plans for Australia's contributions moving towards the operational phase of CTA.

CTA-Pol Update

• Nick Tothill (Western Sydney University)

Optical polarimetry is an identified area in which Australia can contribute to CTA. We are planning to construct a prototype polarimeter to be installed on one or more Australian optical telescopes. We report on CTA-pol progress: Parts have been selected, purchasing is ongoing, and we will shortly start design, prototyping and construction.

Small IACT Arrays - Topological Triggers and AGN Observation

• Simon Lee (School of Physical Sciences, University of Adelaide)

An Imaging Air Cherenkov Telescope (IACT) site in Australia, as part of a worldwide network of IACTs, would be crucial for achieving 24-hour all-sky coverage of the GeV to TeV sky for transient followup and continuous source monitoring. These sources of interest are typically brighter at comparatively low energies, so it’s valuable to study methods to reduce a telescope’s energy threshold. To this end, the effect of implementing a topological camera trigger to small IACT arrays based on CTA designs will be presented, extending on prior studies comparing performance dependent on telescope configuration, and when using a stereoscopic trigger. Additionally, the potential ability for a small array to observe a variety of AGN flares will be shown.

A Bayesian dark matter analysis pipeline for CTA

• Liam Pinchbeck (Monash University)

The Cherenkov Telescope Array (CTA) is poised to revolutionise gamma-ray astronomy. One of the key science goals of CTA is the detection of gamma rays from dark matter annihilation. In this talk, I will describe a new Bayesian pipeline for the detection of dark matter using CTA data. The pipeline builds on top of the popular Gammapy package. The dark matter signal model is described in terms of a prior for the distribution of sky location and gamma-ray energy. Different dark-matter scenarios can be compared using Bayesian model selection. It is possible to marginalise over systematic errors associated with the signal model or the detector response. I discuss the benefits of this approach, and present some preliminary results obtained with mock data of the galactic centre.

SWGO time line and synergies with CTA

• Jose Bellido (The University of Adelaide)

The Southern Wide-field Gamma-ray Observatory (SWGO) will be built in South America to survey the Southern sky for gamma-ray sources from hundreds of GeVs to beyond PeV energies. The candidate site will be decided by the end of 2023 and construction will start in 2024. It is expected that SWGO would be fully built by the end of 2026. SWGO will deploy 6500 particle detectors (Water Cherenkov Detectors) over an area of 1 square km. However, with only 10% of its final size (by early 2025), it will be already larger than the HAWC gamma-ray observatory in Mexico and ready to produce important scientific data. SWGO can observe almost the entire sky above the detector and it has a 100% duty cycle. Therefore, it is the ideal instrument to trigger on transient events (on the Southern Hemisphere) and send rapidly trigger alerts for follow up at other wavelengths. In this presentation I will describe the Observatory and its status. I will focus on the capability to trigger transient events and send trigger alerts to CTA.

AAL/NCRIS Update

• James Murray (AAL)
• Gavin Rowell (School of Physical Sciences, University of Adelaide)

The Gamma-Ray Emission from Mixed-Morphology Supernova Remnants

• Jemma Pilossof (The University of Adelaide)

Mixed-morphology supernova remnants (SNRs) are unique in that the exhibit X-ray and Gamma-ray properties, which are unexpected considering their advanced age. They tend to be rich in stellar ejecta, while they are some of the brightest gamma-ray remnants in our Galaxy. Currently, there has not been a consistent systematic study of the gamma-ray properties of these objects to understand why this population dominates the gamma-ray emitting SNR population. Here we present our results of the first systematic study of the gamma-ray and particle acceleration properties of these SNRs using ~13.5 years of Fermi-LAT data.

New Galactic SNR G288.8-6.3

• Miroslav Filipovic (Western Sydney University)

I will present detection of one of the largest Galactic SNR - G288.8-6.3 that we found in the new ASKAP EMU survey.

Clustering the Interstellar Medium to improve Gamma-ray Modelling of Galactic Objects

• Imogen Barnsley (The University of Adelaide)

High-energy gamma-ray sources can be produced away from the supernova remnant (SNR), due to diffused hadronic cosmic-rays interacting with the interstellar medium (ISM). In order to find the corresponding accelerator, one possible approach is the modelling of gamma-ray emission from this process. The observation of gamma-ray sources can then be compared with the obtained model. In modelling, the gamma-ray emission is very different depending on the location of the interstellar gas clouds in relation to the cosmic rays. However, currently there is no accurate method which can determine the clouds' exact position. Iteration over the positions of the clouds is then necessary to determine a more precise position that produces strong matching between the observed and modelled gamma-ray emission. The volume pixels belonging to each cloud will be determined using clustering which groups a set of data based on similarity. In this talk, I will present the preliminary algorithm developed for clustering the ISM using dendrograms. This was applied to an example region of a well-studied SNR, W28, which I will use to demonstrate the influence of moving the clouds on the modelled gamma-ray emission.

Simulating Light in Scattering-dominated Media

• Gabriel Collin (The University of Adelaide)

Simulating the propagation of particles can be very expensive when scattering lengths and detector sizes are small. I will present a MCMC method to speed up these simulations using the motivating example of propagating light in the IceCube detector.

Update: Improving CTA event reconstruction at the highest energies

• Violet Harvey (The University of Adelaide)

Update: Likelihood-Free Inference applied to CTA

• Tristan Betterman (The University of Adelaide)

In November 2022 we presented a Likelihood-Free Inference (LFI) method for gamma-ray reconstruction at CTA. Since then, we have proceeded an updated dataset in order to fully test the capabilities of the LFI algorithm. Unfortunately, not everything always goes as planned. In this talk we will provide an update on the project and highlight how the choice of training and testing data can have massive impact on the performance of a model when they are not well chosen.

Update: Gamma-ray and Neutrino Emission from Supernova Remnants and Molecular Clouds

• Ryan Burley (The University of Adelaide)

High-energy gamma rays and neutrinos can be produced due to the hadronic interactions between protons escaping particle accelerators such as supernova remnants (SNRs) and nearby target material such as molecular clouds (MCs). By modelling the diffusion of protons escaping SNRs and interacting with nearby MCs in our Galaxy, we can predict the resulting gamma-ray and neutrino fluxes at Earth. Looking towards MCs as production sites for neutrinos may help identify Galactic neutrino sources, as previous searches primarily look at the sites of cosmic-ray accelerators. Observing either the gamma rays or neutrinos at large energies can also point towards Galactic PeVatrons. In this contribution, we will introduce a 3D modelling to calculate the gamma-ray and neutrino fluxes expected from hadronic interactions between a comprehensive list of SNR and MC combinations in our Galaxy. We will update our status on finding promising SNR and MC combinations that, under the right conditions, could produce a gamma-ray flux above 100TeV observable by the Cherenkov Telescope Array (CTA). We also explain how these results can vary under a range of system parameters, such as the gas and supernova remnant properties. These combinations also produce neutrino fluxes that may be observable by future neutrino detectors such as IceCube-Gen2 and KM3NeT.

Update: Modeling Particles in the ISM - Including the ISM’s Influence on the Spatial Distribution of Protons

• Robert König (The University of Adelaide)

SNRs are believed to be a likely sources of Galactic cosmic-ray protons with energies of PeV and above. High-energy protons, escaped from the shock front, diffuse in the ambient ISM and produce gamma rays as products of neutral pion decay from proton-proton interactions. Current models use a constant diffusion coefficient over the whole map to describe cosmic rays travelling through the ambient ISM. The diffusion coefficient depends on the diffusion suppression factor and the magnetic fields a proton traverses. I estimate the local magnetic field along the pathway of cosmic-ray protons estimated by the gas densities of the ISM clouds they pass through and combine this with a model for the change in the diffusion suppression factor. Obtaining a position-dependent diffusion coefficient with a non-symmetric proton distribution

Update: Time Variability of Galactic CRs and the Diffuse TeV Gamma-Ray Emission Predicted with GALPROP

• Peter Marinos (University of Adelaide)

We have simulated the diffuse cosmic-ray sea and gamma-ray emission with GALPROP using a time-dependent solution to the transport equation to ensure the IC emissions are computed accurately. Our predictions are compared to the diffuse emission estimated by the H.E.S.S. telescope array, and the future prospects for detections with CTA will be discussed.

Update: Observations of Ionised Carbon towards SNR RXJ1713.7-3946

• Adnaan Thakur (The University of Adelaide)

I will provide an update on the analysis of gas data towards RXJ1713 and compare them to data obtained from the GOT C Survey.

Update: Unveiling the Scutum Supershell - New Observations

• Rami Alsulami (The University of Adelaide)

In this presentation, I report an optical feature associated with the Scutum Supershell utilising [SII] and H alpha observations. The morphology of the optical structure resembles the outflow that is currently under investigation. Furthermore, we conducted a X-ray analysis to determine the flux using PIMSS, incorporating ROSAT PSPC and MAXI SSC observations of the region.