Bachelor and MSc thesis with CTAC (Center for Theoretical Astrophysics and Cosmology), Institute for Computational Science (UZH)

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1 Bachelor and MSc thesis with CTAC (Center for Theoretical Astrophysics and Cosmology), Institute for Computational Science (UZH) General topics: (i) Theoretical and computational astrophysics: origin of galaxies, stars, planets, black holes (ii) Computational cosmology: emphasis on cosmic structure formation in cold dark matter model (iii) Computational science: emphasis on computational fluid dynamics For inquiries use:

2 At CTAC we base our work on advanced supercomputer simulations as well as on semi-numerical models that you can run on your workstation Currently ~ 25 PhD and MSc students (some joint with ETH Zurich) working primarily on designing, analyzing and interpreting computer simulations using the fastest parallel supercomputers (at UZH, at the Swiss National Supercomputing Center, at european PRACE facilities, NASA and DOE facilities in the US etc..) PLEASE TAKE NOTE: our current cosmological structure formation paradigm or our current theories of star and planet formation are primarily driven by simulation work because astrophysical systems are modeled via solution of multiple nonlinear partial differential equations, with associated spatial and temporal scales varying by up to 10 orders of magnitude

3 MsC and PhD thesis work at CTAC has often led to high-impact results in astrophysics and cosmology (check press releases on our website!) Strong link with Swiss National Supercomputing Center, possibility to develop projects at the boundary between computer science, applied math and astrophysics (PASC program - Platform for Advanced Scientific Computing, current PI Lucio Mayer) Opportunities to design new computational methods or codes for simulations, or refine existing ones to exploit new hardware technologies such as GPUs (compute more accurate and faster!) Two types of projects at CTAC: (a) Science focused (b) Computational method focused

4 Astrophysical Topics and Research Groups Leaders Cosmological Structure Formation Relativistic Cosmology and Large Scale Structure Joachim Stadel, Ben Moore, Romain Teyssier Jaiyul Yoo, Prasenjit Saha (gravitational lensing) Galaxy dynamics and Galaxy Formation George Lake, Lucio Mayer, Romain Teyssier, Robert Feldmann Star Formation and Interstellar Gas Astrophysics of Black Holes and gravitational waves Planet Formation Planetary Evolution and Interiors Robert Feldmann, Romain Teyssier, Lucio Mayer Lucio Mayer, Philippe Jetzer (Physik) Lucio Mayer, Ravit Helled Ravit Helled, Joachim Stadel NOTE: Mayer, Moore & Stadel key members of national project PlanetS (NCCR) - largest form of project funding in Switzerland

5 ERIS - first realistic simulation of a spiral galaxy (2011) Solved long-standing problem in cosmology. Till 2011 many thought galaxies like our own Milky Way could not form in a Universe dominated by (cold) dark matter The ERIS simulations (Guedes, Callegari, Madau & Mayer 2011; Guedes, Mayer, Carollo, Madau 2012; Mayer 2012;Shen et al. 2011; 2012) Both Callegari and Guedes were MsC and then PhD students (at UZH and UC Santa Cruz)

6 Analysis and interpretation of simulations I: Star formation in turbulent molecular gas clouds; zooming inside individual star forming regions, study protostellar disk and protostar with AMR technique

7 Analysis and interpretation of simulations II art hydro simulation of multiple gas giant planet formation by gas disk gravitational instability - on Hybrid CPU+GPU Cray Piz Daint at Swiss Supercomputing Center (CSCS) Here scale of disk is 150 AU, mass ~ 0.7 Mo.

8 Another project flavour: Use real astronomical data to build new theoretical scenarios (later build simulation) A new puzzle: Ultra Diffuse Galaxies (UDGs) They have > 10 times the dark matter content of normal galaxies! But maybe just more massive version of the faint dwarf galaxies in our Local Group of Galaxies? To find out put together all the structural data available for UDGs and Local Group dwarfs and look for trends and possible correlations (open-ended, for Bsc or Msc)

9 A whole new exciting area: Black hole binaries and gravitational waves!

10 NEW PHENOMENON DISCOVERED WITH PHD STUDENT DAVIDE FIACCONI AND FORMER MSC STUDENT RAFAEL SOUZA-LIMA (FIACCONI ET AL. 2013, SOUZA-LIMA ET AL. 2016): SUPERMASSIVE BLACK HOLES (SMBHS, M > 10 6 SOLAR MASSES) ARE SCATTERED EFFICIENTLY BY GAS CLOUDS IN TODAY S GALAXIES---> MERGING OF SMBHS LESS EFFICIENT THAN PREVIOUSLY THOUGHT IMPLICATIONS FOR FUTURE GRAVITATIONAL WAVE EXPERIMENTS M 1 M 2 Fiacconi et al. (2013)

11 Cosmological context: cold dark matter halos and subhalos Via Lactea II: for long was the reference simulation to understand nature and distribution of dark matter in our Galaxy (Diemand et al. 2007)

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