In Person in Marlar and/or Virtual Brown Bag Lunch
Monday December 5, 2022 at 12:00 Link Below
Join BBL Zoom Meeting
Presentation in Marlar 37-252/37-272 for those wishing to attend in person
Philipp Kempski, Princeton at 12:05 (in person)
Cosmic Ray Feedback and Instabilities in Galaxy Clusters
Abstract: Most of the baryonic mass in galaxy clusters resides in the hot and dilute Intracluster Medium (ICM). In this talk, I will discuss how relativistic cosmic rays (CRs) injected by central Active Galactic Nuclei may affect the evolution of the ICM. In particular, I will demonstrate that CRs can efficiently excite waves, which may subsequently travel and dissipate across the ICM. This has potentially significant implications for the long-standing puzzle of how thermal balance is maintained in the cores of galaxy clusters.
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Emily Charles, Surrey, UK at 12:30 pm (remote)
Andromeda 25 – a dwarf galaxy with a low central dark matter
Abstract: The most successful model of the Universe to date is the Lambda Cold Dark Matter Model (LCDM). Theoretical predictions from LCDM on large scales closely match observational evidence. However, on small scales (e.g. galactic scales) long-standing tensions between theory and observation exist. Dwarf galaxies are dark matter dominated systems, making them powerful probes for studying dark matter on small scales. Recently I have been focusing on Andromeda 25 (And 25), a dwarf satellite galaxy of M31. And 25 was previously identified in Collins et al (2013) as an outlier with little-to-no dark matter content. However, this conclusion was heavily caveated due to the small sample size of only 26 stars. With the inclusion of new spectroscopic data, we more than doubled the sample size. In this talk, I will discuss the revised kinematic results of And 25 to find out if it truly is a dwarf galaxy with no dark matter component. I will then expand the discussion to include results from the dynamical mass modelling of And 25 to investigate its unusual dark matter profile and potential explanations for its low central dark matter density.