Annual Scientific Meeting & Harley Wood School

Session

AGN

7 Jul 2025, 10:00

University of Adelaide

33. Probing AGN Accretion Discs through their Variability

Ashley Hai Tung Tan (Australian National University)

07/07/2025, 10:00

Oral

AGN accretion discs cannot be directly resolved, making flux variability a powerful probe of their internal structure and accretion processes. However, host galaxy contamination complicates variability studies of low-luminosity AGN. To address this gap, we characterise the optical variability of a sample of ~250 low-luminosity AGN at z < 0.1 through the ensemble variability structure function...

42. Seeing the full picture: measuring AGN feedback with next-generation radio jet models

Samuel Hansen

07/07/2025, 10:15

Oral

Active Galactic Nuclei (AGN) jets are the brightest objects in the radio sky. Their feedback is an essential ingredient in all galaxy formation models. Tens of millions of AGN jets have been discovered over the past decade with more promised by the SKA. Measuring the energy output of these jets is a notoriously challenging, requiring either analytical or numerical jet models. In this work, for...

83. Disentangling AGNs from Stellar contributions to the Cosmic Spectral Energy Distribution

Kavin Kumar Nagarajan Rajkumar (International Centre for Radio Astronomy Research - University of Western Australia)

07/07/2025, 10:30

Oral

A galaxy’s total radiation arises from a combination of processes including star formation, dust and gas reprocessing, accretion, and magnetic interactions. While star formation typically dominates the optical and infrared emission of galaxies, AGNs contribute significantly at X-ray, mid-infrared, and radio wavelengths. Even a modest AGN contribution can bias key derived quantities such as...

20. Jet Outbursts, Non-thermal Pressure and the AGN Duty Cycle

Andrew Sullivan (The International Centre for Radio Astronomy Research (UWA))

07/07/2025, 10:45

Oral

The hot intracluster gas within galaxy clusters experiences shocks, mergers, and active galactic nucleus (AGN)-driven feedback, all of which drive its overall pressure distribution, which is crucial for understanding the mass and composition of these systems. 'Non-thermal pressure' (NTP) - gas pressure not attributed to random motion - is generated during these processes, but is challenging to...

2. Unveiling the Nature of High-Redshift Galaxies with JWST: Challenges and Insights from Theory and Simulations

Yuxiang Qin (Australian National University)

11/07/2025, 10:00

Oral

Recent JWST observations have revealed an unexpected abundance of bright galaxies at z ≳ 12, both in the UV and as Lyman-α emitters, challenging standard galaxy formation models and our theoretical expectation of reionization in the early universe. Using a semi-analytic galaxy formation model, we find that while faint JWST galaxies align with predictions, bright galaxies require enhanced star...

12. Hidden in plain sight: building towards finding rare, powerful radio galaxies at z>6 in the SKA era

Alexander Hedge (ICRAR/Curtin University)

11/07/2025, 10:15

Oral

High-redshift AGN are a key puzzle piece to understanding the full picture of galaxy evolution due to the co-evolution of supermassive black holes and host galaxies. Across cosmic time, radio-loud obscured AGN are beacons of massive black holes and host galaxies, but at z > 5 this population remains elusive (with fewer than five known). The most massive and powerful of these radio-loud AGN are...

173. How biased are JWST high-z quasar host galaxy detections?

Sabrina Berger (University of Melbourne)

11/07/2025, 10:30

Oral

The James Webb Space Telescope (JWST) has revolutionized the study of quasars in the high-z Universe. For the first time, astronomers have detected and characterized nearly 10 galaxies that host bright quasars at z > 6, a fundamental step in understanding the co-evolution of galaxies and their supermassive black holes (SMBHs) across cosmic time. Initial stellar mass measurements of these...

129. The CosmoDRAGoN simulations: radio jet feedback and spectral signatures in cosmological environments

Patrick Yates-Jones

11/07/2025, 10:45

Oral

Galaxy formation and evolution over cosmic timescales are driven by active galactic nuclei (AGN) feedback. The kinetic-mode feedback of powerful radio jets launched from AGN shock-heat the intra-cluster medium, influence star formation through driven turbulence, and uplift rapidly cooling gas to large cluster radii. There is a clear need to understand and quantify the effects of this feedback...