Join us on Thursday, April 24th for a special edition of our Spring Physics Colloquia series! Guest lecturer, Dr. Andrea Gokus, will be visiting from the Washington University in St. Louis and present two talks!

 

Special Seminar - Can We Do Big Science Sustainably? Advocating for Greener Astronomy

 

11:00AM in Disque 109

 

Abstract:

Astronomers for Planet Earth (A4E) is a global grassroots movement founded six years ago to confront the climate crisis from an astronomical perspective. As astronomers, we offer a unique view point on Earth, that is, seeing it as a fragile oasis in the vast expanse of space.
A4E engages both the public and students through outreach and education on climate change and the consequences of inaction. Beyond raising awareness, A4E members also advocate for more sustainable practices within the field of astronomy, aiming to reduce astronomy’s carbon footprint by implementing practical, existing solutions.

As part of this effort, I led a study assessing the travel-related emissions of astronomers in the pre-pandemic year of 2019. The results were, quite literally, astronomical: the combined travel distance for conferences and meetings exceeded 1.5 astronomical units (AU). While in-person meetings are often seen as more effective for networking and collaboration, they come with significantly higher carbon costs and tend to be less inclusive than well-designed virtual alternatives.

 

Colloquium -  Gamma-Ray Signals from the Early Universe: The Hunt for Distant Blazars

 

Abstract:

At the centers of galaxies lie supermassive black holes. While most remain dormant, roughly one in ten actively accretes surrounding material, releasing enormous amounts of energy. These so-called active galactic nuclei (AGN) can outshine their host galaxies, making them some of the brightest objects in the Universe.
Some AGN also launch powerful, relativistic jets, which are narrow beams of particles accelerated to nearly the speed of light. These jets can shape their environments on both galactic and intergalactic scales, influencing star formation and galaxy evolution. When one of these jets is pointed toward Earth, we observe an exceptionally bright and highly variable object known as a blazar.

Blazars emit across the entire electromagnetic spectrum and can be observed at the highest photon energies with gamma-ray telescopes. Due to their variability and brightness, they are ideal laboratories for studying the most energetic processes in the Universe. Their high luminosities allow us to detect them across cosmic time, providing unique insights into black hole growth and galaxy evolution from the early Universe to today.

To date, the Fermi Large Area Telescope (LAT) has detected over 3,700 blazars at GeV energies. However, studying their evolution and the influence of their jets across cosmic history requires observing blazars at high redshifts, where detections become increasingly difficult. Only a small number of these distant sources have been identified in gamma rays, limiting our understanding of jetted AGN around the time of cosmic noon.
In this talk, I will discuss how we can search for gamma-ray emission from high-redshift blazars by leveraging their transient nature. I will also present results from a multi-wavelength campaign targeting two such sources, incorporating observations across the radio, optical, and X-ray bands.

 

Can't make it? Join us on Zoom!

Passcode: 969860