Upcoming talks

Thu 10 Apr 11:30: Probing Black Hole Winds with SimBAL: Mapping the Physics of Broad Absorption Line Quasar Outflows KICC Special Seminar

Mon, 31/03/2025 - 14:10

Probing Black Hole Winds with SimBAL: Mapping the Physics of Broad Absorption Line Quasar Outflows

Broad absorption line (BAL) quasars provide striking evidence of energetic winds driven by accreting supermassive black holes. These outflows are thought to play a crucial role in regulating black hole growth and the host star formation rate, as well as shaping the evolution of galaxies; however, their physical properties—such as radius and energetics—remain poorly constrained. Our group has developed SimBAL, a spectral synthesis tool that enables detailed, physically motivated modeling of BAL quasar spectra. It has allowed us to perform a detailed spectral analysis of a large sample of BAL quasars for the first time and to characterize multi-phase outflows in a quasar discovered at the Epoch of Reionization. I will demonstrate SimBAL’s unique strengths by discussing the results from several projects and how our group has taken a systematic approach to investigate the physics of black hole winds. Lastly, I will introduce the 4MOST–Gaia Purely Astrometric Quasar Survey, an upcoming spectroscopic survey uniquely designed to deliver the first large-scale, color-independent quasar reference sample.

KICC Special Seminar

Speaker: Hyunseop (Joseph) Choi (Université de Montréal)
Thursday 10 April 2025, 11:30-12:00
Venue: Ryle Meeting Room, KICC.
Series: Kavli Institute for Cosmology Seminars; organiser: Steven Brereton.

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Thu 10 Apr 11:30: Probing Black Hole Winds with SimBAL: Mapping the Physics of Broad Absorption Line Quasar Outflows KICC Special Seminar

Mon, 31/03/2025 - 08:53

Probing Black Hole Winds with SimBAL: Mapping the Physics of Broad Absorption Line Quasar Outflows

Broad absorption line (BAL) quasars provide striking evidence of energetic winds driven by accreting supermassive black holes. These outflows are thought to play a crucial role in regulating black hole growth and the host star formation rate, as well as shaping the evolution of galaxies; however, their physical properties—such as radius and energetics—remain poorly constrained. Our group has developed SimBAL, a spectral synthesis tool that enables detailed, physically motivated modeling of BAL quasar spectra. It has allowed us to perform a detailed spectral analysis of a large sample of BAL quasars for the first time and to characterize multi-phase outflows in a quasar discovered at the Epoch of Reionization. I will demonstrate SimBAL’s unique strengths by discussing the results from several projects and how our group has taken a systematic approach to investigate the physics of black hole winds. Lastly, I will introduce the 4MOST–Gaia Purely Astrometric Quasar Survey, an upcoming spectroscopic survey uniquely designed to deliver the first large-scale, color-independent quasar reference sample.

KICC Special Seminar

Speaker: Hyunseop Choi (Université de Montréal)
Thursday 10 April 2025, 11:30-12:00
Venue: Ryle Meeting Room, KICC.
Series: Kavli Institute for Cosmology Seminars; organiser: Steven Brereton.

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Fri 04 Apr 11:30: The first stars: window to cosmic dawn

Fri, 28/03/2025 - 18:09

The first stars: window to cosmic dawn

The era of cosmic dawn began with the first stars that formed in the Universe a mere 200 – 300 million years after the Big Bang. These stars produced the first supernovae and black holes, enriched the interstellar medium (ISM) with metals, were the building blocks of the first galaxies, and significantly contributed to cosmic reionization. However, compared to star formation and feedback in metal-rich environments today, the lack of direct observations at low metallicities as well as high redshifts has posed a significant challenge for understanding the physics behind their formation and evolution. In this talk, I will introduce POPSICLE , a new framework for high resolution simulations that caters to star formation and feedback in low metallicity ISM reminiscent of redshift > 10 galaxies. I will describe how incorporating the full spectrum of ISM physics coupled to stellar evolution is crucial to constrain the stellar initial mass function (IMF) and feedback in such environments. I will particularly focus on Population III stars, and discuss their potential as seed black holes in the early Universe. I will conclude by showcasing the capability of GPU -accelerated simulations to revolutionize our understanding of the astrophysics of cosmic dawn, and to bring theory at par with state of the art observations from JWST .