Date/Time
Date(s) - 08/03/2023
3:30 pm - 4:30 pm

Physics & Astronomy
Colloquium
Date: 8 March 2023
Time: 3:30 pm
Location: ABB 102
Light Refreshments starting at 4:30 pm in ABB 245
Guest: Dr. Viraja Khatu
Postdoctoral Researcher, Western University
Host: Dr. James Wadsley

Title: Light Echoes in Gigantic Black Holes Narrate the Story of Black Hole Growth

Abstract:
In the hearts of massive galaxies live supermassive black holes (compact objects millions to billions of times the mass of our Sun).  Some of these gigantic black holes actively accrete through a disk of ionized gas, releasing tremendous energy in the form of light – in this phase, they are called active galactic nuclei (AGN).  Despite decades of efforts, we still do not have a clear picture of the structure and gas motions in AGN.  Investigating the inner structure and dynamics of a large number and diverse populations of AGN is critical to answer a key question in AGN science, ‘How do supermassive black holes grow over cosmic time?’.  AGN appear point-like in images; hence, we rely on a powerful, time-domain method to study their interiors.  The time-domain method harnesses the information of how light output in AGN changes and ‘echoes’ over time, to derive the size scales of these objects.  Combining AGN sizes with their gas velocities and the laws of gravity, we can obtain the central black hole masses in AGN to help understand black hole growth.  In my talk, I will cover why it is important to study AGN, how we apply the time-domain technique to map their interiors, and what science goals can be achieved with AGN data from existing and future observatories including results from my recent work.
Zoom Link:

Topic: P&A Colloquium – Dr. Viraja Khatu
Mar 8, 2023
3:30 pm

Join Zoom Meeting
https://mcmaster.zoom.us/j/96354473065?pwd=N3dLck42WkE3WXM2eUZUN1Y5MnhIUT09

Meeting ID: 963 5447 3065
Passcode: 512801
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