[Astro] Astro seminar Wed 9th Oct 15:45 C5 -- Elke Roediger (Hull)

[Luke Conaboy]

Hi all,

this week's astronomy seminar will be given by Elke Roediger, talking about interpreting cluster merger observations. Elke will be here all day on Wed.

Post-seminar refreshments will be wine and cheese.

Timings are as usual:

- lunch at Lakeside, leaving CAPT ~13:00 (subsidised for a limited number of students - let me know before the end of the day tomorrow)
- meet the speaker for postgrads at 15:00, finishing at 15:30
- seminar at 15:45 in C5
- post-seminar wine and cheese at 16:45

This seminar will be conducted in person only.

Best,
Jesse and Luke

==

Interpreting cluster merger observations: catching some devils in the details

In minor galaxy cluster mergers, several interesting gas dynamics phenomena take place. These include the formation of a bow shock by the supersonically infalling smaller merger partner, an enhanced stagnation point pressure just upstream of the infalling subcluster, gas stripping of the smaller partner, and gas sloshing of the larger host cluster. Theoretical and numerical work has advanced our understanding of these processes and their associated observable signatures. These effects, or similar ones, are also known in Earth-bound gas flows, and simple analytical estimates have been used to derive properties such as merger ages and infall speeds from observations. However, the applied methods often rely on at least quasi-steady gas flow conditions, which can’t be assumed in cluster mergers due to density gradients in the ICM and non-constant merger velocities. 
I report on two lines of our research: We investigate to what extent the non-steady state nature of gas flows in mergers biases measurements of merger velocities, and we present an analytical toy model for cluster sloshing.