DRAO Seminar Series 2021


Time & Date Speaker Title
14:00 Wed Jan 20 Nathan Leigh
University of Concepción Chile
Remote Talk: Chaos in the Gravitational Three-Body Problem
14:00 Wed Jan 27 Lichen Liang
University of Zurich / Canadian Institute for Theoretical Astrophysics (U Zurich/CITA)
Remote Talk: Probing dust emission in high-redshift galaxies using FIRE simulations
14:00 Wed Feb 3 Gordon MacLeod
Hartebeesthoek Radio Astronomy Observatory
Remote Talk: Monitoring for serendipity – the cure to boredom
14:00 Wed Feb 10 Charles J. Lada
Harvard-Smithsonian Center for Astrophysics
Remote Talk: TBD
14:00 Wed Feb 17 Laura Fissel
Queen’s University
Remote Talk: TBD
14:00 Wed Feb 24 Yik Ki (Jackie) Ma
ANU & MPIfR
Remote Talk: TBD
11:00 Wed Mar 10 Russ Taylor
University of Cape Town
Remote Talk: TBD
14:00 Wed Apr 7 Lynne Hillenbrand
Caltech
Remote Talk: Young Stellar Objects in the Multiwavelength Time Domain

Remote Talk: Chaos in the Gravitational Three-Body Problem

Nathan Leigh (University of Concepción Chile)

The gravitational three-body problem has a long history, extending all the way back to Sir Isaac Newton. In spite of hundreds of years of research, we still do not have a complete solution to the general case, where no restrictions are placed on the nature of the interaction. Historically, this has been attributed to the appearance of chaos in large regions of parameter space, implying that a probabilistic theory is the only way to go. In this talk, I will briefly review the general three-body problem and its present-day astrophysical significance. I will then go on to introduce a probabilistic solution for the outcomes of chaotic three-body interactions mediated by gravity, and describe how my collaborators and I are using this new tool to build a model that evolves entire populations of binary stars in dense star clusters due to three-body interactions with single stars. The model is entirely analytic, and covers regions of parameter space that are only accessible to modern simulations with great computational cost.

Remote Talk: Probing dust emission in high-redshift galaxies using FIRE simulations

Lichen Liang (University of Zurich / Canadian Institute for Theoretical Astrophysics)

Fruitful information about the galaxy properties can be derived from the spectral energy distribution (SED) of the dust thermal continuum, including the star formation rate (SFR) and dust and gas mass of galaxies, which are critical for understanding galaxy evolution. In practice, however, this can be challenging at high redshifts because most high-z objects have merely a few photometric data points in the dust SED owing to the high confusion noise of the infrared instruments and limited number of bandpasses available. To infer LIR (and hence SFR) and gas mass of high-z galaxies thus requires understanding how far-infrared dust SED is shaped, which is the main topic of this talk. I will show the results obtained from the recent studies using the latest FIRE (Feedback in Realistic Environments) simulations coupled with radiative transfer technique. Specifically, I will discuss the physical mechanisms for shaping the far-infrared SED of galaxies, with a particular emphasis on the role of dust opacity and dust temperatures. In addition, I will discuss the physical origin of the IRX-βUV relation, a technique commonly adopted for deriving LIR of galaxies based the UV data alone, and assess the different sources of both the intrinsic scatter as well as the observational biases of this relation. The results to be presented link the theoretical study of galaxies at high redshift to observational constraints, which provide new insights into the growth of galaxies and the physical processes driving the cosmic star formation history.

Remote Talk: Monitoring for serendipity – the cure to boredom

Gordon MacLeod (HartRAO)

Serendipity is enhanced via time domain observations at multiple transitions in several molecules increases. The Maser Monitoring Organisation (M2O) was created by an international group of researchers, telescope managers, and students, to confirm, coordinate, and collaborate on maser monitoring and associated phenomena. Its success is evident in a plethora of publications on bursting water masers and significant accretion events. This presentation is a compilation of primarily HartRAO observations of maser monitoring, augmented by M2O observations, towards accretion events and other interesting results associated with High Mass Star-Forming Regions. Serendipity is our friend!

Remote Talk: TBD

Charles J. Lada (Harvard-Smithsonian Center for Astrophysics)

TBD

Remote Talk: TBD

Laura Fissel (Queen’s University)

TBD

Remote Talk: TBD

Yik Ki (Jackie) Ma (Australian National University & Max Planck Institute for Radio Astronomy)

TBD

Remote Talk: TBD

Russ Taylor (University of Cape Town)

TBD

Remote Talk: Young Stellar Objects in the Multiwavelength Time Domain

Lynne Hillenbrand (Caltech)

TBD