Virtual Brown Bag Lunch and Marlar Screening
Monday, April 25, 2022 at 12:00 Link Below
Join BBL Zoom Meeting
Presentation in Marlar for those wishing to attend in person
Jan David Burger, University of California at Riverside at 12:05
Breaking the degeneracy between supernova feedback and SIDM as core formation mechanisms
Abstract: Reconciling the success of LCDM on large scales with observational hints for cored DM haloes at the scale of dwarf galaxies requires a physical mechanism to flatten the ubiquitous cusps predicted by CDM N-body simulations. While several proposed mechanisms yield nearly identical cores, the timescale on which the gravitational potential changes as the core forms differs strongly between them. In this talk, I present characteristic baryonic signatures of supernova feedback and SIDM that arise as a consequence of the impulsiveness of the former core formation mechanism — or the adiabaticity of the latter. I argue that future surveys of isolated nearby dwarf galaxies with significant recent star formation (and cored DM host haloes) will enable us to differentiate between these two mechanisms.
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Konstantinos Migkas, Bonn at 12:30 pm
The (an)isotropy of the local Universe as seen through galaxy clusters
Abstract: We utilize a new powerful method to scrutinize the most crucial cosmological assumption; the isotropy of the late Universe. We use ten multi-wavelength cluster scaling relations between cosmology-dependent and cosmology-independent cluster properties to study the spatial variation of the Hubble constant H0 and the existence of large cluster bulk flows. We robustly detect a 9% dipole anisotropy of H0 in the local Universe (z<0.2) at a 5.9 sigma level. Alternatively, this could be attributed to a 900 km/s cluster bulk flow, extending out to at least 500 Mpc. Both scenarios strongly contradict LCDM.