[ASA] ASA ECR Symposium Series: Samuel Lai (Australian National University) at the University of Queensland, Monday, 11 September, 11:00 AEST

Amit Seta amit.seta at anu.edu.au
Fri Sep 8 14:29:32 AEST 2023

Dear ASA members,

As part of the ASA ECR Symposium Series, Samuel Lai (Australian National University) will be giving a talk at the University of Queensland on Monday, 11 Sep. at 11 am AEST. Please find the title, abstract, and the zoom link to join online below.

Unsolved Mysteries of the Active Galactic Nuclei Paradigm: Clues from High Redshift Quasars

The time-honoured paradigm for active galactic nuclei (AGN) contends that the apparent diversity of observed phenomena are unified under different orientations. However, not long after its proposal, the aggregate evidence reveal that the simplest viewing-angle based models are incomplete. Part of the reason for this enduring controversy is the challenge of directly measuring orientation or intrinsic black hole properties. In this work, we direct our attention to some of the most luminous unlensed quasars (QSOs) visible in the Southern Sky. We obtain multiwavelength rest-frame optical/UV data and discuss the information encoded in velocity-broadened spectral features traced back to ionised gas in close proximity to the black hole accretion disc. We also develop a complementary method to constrain black hole by utilising ray-traced models of the multi-temperature thermal accretion disc emission, demonstrating how the independent methods produce compatible results and releasing all of the spectral and accretion disc modelling software packages for public use. In conjunction, we exploit a recently discovered universality in the QSO variability structure function to explore a novel orientation indicator. This work lays the foundation for a QSO 'main sequence', which would be a development with cosmological significance, due to the potential for QSOs to be observed at high-redshift in a young Universe.

Zoom link:
https://protect-au.mimecast.com/s/crpYCD1vlpToyqzD0iWBxJA?domain=uqz.zoom.us (Password: UQ)

Please join us to know more about the mysteries of AGN paradigm from Samuel.

Thank you,
Best regards,
on behalf of the ASA ECR Chapter Steering Committee

Dr. Amit Seta (he/him/his)
Senior Research Fellow
Research School of Astronomy & Astrophysics
Australian National University, Canberra, ACT, Australia

Email: amit.seta at anu.edu.au<mailto:amit.seta at anu.edu.au>
Phone No.: +61 (02) 6125 2489
Webpage: https://protect-au.mimecast.com/s/Cq_cCE8wmrtlYL2kMtwcehY?domain=mso.anu.edu.au
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