Seminar Speaker

Evan Keane

Venue

B10A, Basement of Kane Science Building, UCC

Time/Date 

4pm / Monday, 25 Nov, 2024

Title

SKA Ireland

Abstract

The Square Kilometre Array is a scientific mega project, the next generation radio astronomy observatory. It is currently under construction in two remote sites - one in the Karoo in South Africa and one in the Murchison in Western Australia. I will overview the scientific goals of the SKA Observatory and show recent highlights
from its ongoing construction. SKA-Low (the Australian component), with 4 stations of the eventual 512 now complete has already well surpassed the performance of the Irish LOFAR station and next year will surpass the LOFAR core, before continuing to make order-of-magnitude strides in capabilities. I will also describe SKA Ireland, a group consisting of members from 17 institutions on the island, which advocates for Ireland to join the SKA project. I will give the views of the group and look forward to hearing the views of the community in UCC.

Seminar Speaker

Christian Ginski

Venue

B10A, Basement of Kane Science Building, UCC

Time/Date 

4pm / Monday, 18 Nov, 2024

Title

Traces in the sand - Hunting for the youngest planets

Abstract

With thousands of extrasolar planets discovered we are facing a major problem in planet-formation theory: How to explain the huge diversity of system architectures that are all seemingly very alien from the solar system? To trace this problem to its origin we have to turn to the beginning of the planet formation process and study the youngest planets in their natal environment, the dust and gas rich disks surrounding young stars. High resolution observations of these objects in the past decade have shown them to be just as diverse as the exoplanet population. Notably many disks (when observed at sufficiently high resolution) exhibit structures that may be explained by ongoing planet-disk interaction. I will showcase some of the latest results of these studies and how the disks point us to the planets.

Seminar Speaker

Michael Tremmel 11 Nov 2024 

Venue

B10A, Basement of Kane Science Building, UCC

Time/Date 

4pm / Monday, 11 Nov, 2024

Title

The Evolution of Massive Black Holes: Current Insights from Cosmological Simulations

Abstract

I will provide an overview of the wealth of current insights from both cosmological simulations on the evolution of massive black holes (MBHs). These simulations produce important predictions for MBH mergers that are relevant for LISA and are crucial tools for bridging the gap between large-scale structure formation (on Megaparsed scales), galaxy-scale physics (kiloparsec scales), and black hole binary evolution (parsec to sub-AU scales), all of which are needed to fully characterize the MBH binary/merger population.  I will discuss these predictions and how gravitational wave observations have the potential to constrain the highly uncertain physics of MBHs. I will also compare and contrast predictions across simulations and current observational constraints, including recent results from JWST. Finally, I will highlight the challenges that simulations face in this new era of high-redshift, multi-messenger astrophysics that will utilize both electromagnetic emission and gravitational waves to discern the earliest phases of MBH-galaxy co-evolution.

Seminar Speaker

Dr Johanna Vos

Venue

B10A, Basement of Kane Science Building, UCC

Time/Date 

4pm / Monday, 21 Oct, 2024

Title

 Exometeorology: Weather on Worlds Beyond our Own

Abstract

Major technological advances have enabled the discovery of a small number of directly imaged exoplanets. These imaged worlds can be studied in far greater detail than exoplanets detected by indirect methods such as transit and radial velocity techniques. Next-generation telescopes such as the recently launched James Webb Space Telescope and the upcoming 30-m telescopes (e.g. ELT, TMT, GMT) will enable direct exoplanet characterisation. Based on the handful of exoplanets studied to date, it is clear that interpretation of future observational data hinges on a thorough understanding of their atmospheric processes. In this talk I will discuss our past, current and future efforts to investigate the atmospheres of extrasolar worlds. In particular, I will discuss how a combination of observational and computational techniques will reveal three critical atmospheric processes: clouds, winds and aurorae. Each of these processes are well-studied in our own Solar System and we can now begin to study them on worlds beyond our own.

Seminar Speaker

Dr. Fan Liu (Monash University, Australia)

Venue

B10A, Basement of Kane Science Building, UCC

Time/Date 

4pm / Monday, 23 Sept, 2024

Title

Stellar Chemical Signatures of Planetary Ingestion and Planet Formation

Abstract

Ingestion of planetary material and/or planet formation can imprint a distinct chemical signature into the host star’s photosphere. Detecting these ‘planet signatures’, however, is challenging due to unknown occurrence rate, small amplitudes of planet signals and heterogeneous star samples with large differences in stellar ages. Co-natal stars (e.g. binary stars and open clusters) offer a unique opportunity to detect stellar chemical signatures of planets thanks to their shared origin and identical initial chemical composition. Here we establish and report high-precision chemical abundances (~ 0.015 dex; 3%) for a large, homogeneous sample of 125 pairs of stars moving together (91 with shared origin, i.e., co-natal) with a well defined selection function using Gaia DR3. Our sample represents a ten-fold increase in sample size and a least five-fold increase in precision over traditional spectroscopic analysis of binary star systems. We identified at least 7 new instances of planetary ingestion, corresponding to an occurrence rate of about 8%. An independent Bayesian indicator was deployed, which can effectively disentangle the planet signatures from other factors, such as random abundance variation and atomic diffusion. Our study thus provides clear evidence of planet signatures and facilitates a deeper understanding of the star–planet–chemistry connection by providing observational constraints on the mechanisms of planet engulfment, formation and evolution.

Seminar Speaker

Jerry Moloney, Arizona Center for Mathematical Sciences and Wyant College of Optical Sciences
University of Arizona

Venue

G7, Kane Science Building, UCC

Time

4pm / Monday, 12th Sept, 2024

Title

"Microscopic physics of ultrafast resonantly and non-resonantly driven 3D and 2D
semiconducting materials”

Abstract

Semiconductors, undergoing resonant or far from resonant interactions with ultrashort
laser pulses, exhibit fundamentally different nonlinear and nonequilibrium behavior.
Semiconductor disk lasers (SDLs), where light is extracted through the top surface, are
subject to very strong departures from quasi-equilibrium Fermi distributions, when
operating in pulsed mode. GHz repetition rate, multi-wavelength channel SDLs,
accommodate individual mode-locked pulse trains, exhibit extreme nonlinear and
nonequilbrium dynamics and extract photons from separate kinetic holes burned within
carrier reservoirs. By way of contrast, highly non-resonant strong field interactions with 3D
and 2D semiconductors, promote both direct interband and intraband currents driving high
harmonic generation and involve carrier transport across the full Brillouin zone. My talk will
begin by reviewing a broad class of experiments by our group, guided by microscopic manybody
physics. I will then discuss the application of the microscopic theory to resonant laser
operation and strong-field off-resonant driven 3D and 2D semiconducting materials.