TTK Theory Seminars WS 18/19


Thu 04.04.2019, 16.30 h

S. Recchia (Paris)

Cosmic rays in the turbulent interstellar medium

The cosmic ray(CR) spectrum detected at Earth is a non-trivial combination of the spectrum released by the sources and of the CR propagation and interaction with the interstellar medium (ISM). CRs in the ISM are scattered by the turbulent magnetic field, and, depending on their energy and species, they can incur in severe energy losses. In addition, CRs  can  themselves  excite magnetic  turbulence  in  the background plasma and generate large scale flows like galactic winds, thus affecting their own transport. In this talk I will discuss some  implications of the CR-ISM interaction, in particular  the formation of galactic winds,  the CR escape and propagation in the source proximity,  the identification of the sources of TeV CR electrons and  the ionization of molecular clouds.


Thu 18.04.2019, 16.30 h

N. Bozorgnia (IPPP Durham)

The dark matter distribution in the Solar neighbourhood

The dark matter density and velocity distribution in the Solar neighbourhood are important inputs in the analysis of data from direct detection experiments. Uncertainties in these astrophysical inputs complicate the interpretation of direct detection results, and prevent a precise determination of the particle physics properties of dark matter. High resolution hydrodynamic simulations of galaxy formation have recently become possible and provide important information on the properties of the dark matter halo. I will discuss the local dark matter distribution of Milky Way-like galaxies extracted from state-of-the-art hydrodynamic simulations, present an analysis of direct detection data using this distribution, and discuss the possibility of dark disks. I will also explore possible correlations between the stellar and dark matter velocity distributions, and discuss if there is a subset of stars which trace the dark matter distribution in various simulated Milky Way-like galaxies.


Thu 25.04.2019, 16.30 h

C. Byrnes (U. Sussex)

Cosmology with primordial black holes

Primordial black holes (PBHs) could be part or all of the dark matter, but even if they don’t exist, they constrain the initial conditions of the Universe and inflation. In this talk I discuss how the non-detection of PBHs constrains the primordial power spectrum over a wider range of scales than any other probe. I will discuss some of the subtleties associated with making these constraints, including their dependence on the shape of the primordial power spectrum (which cannot be steeper than k^4), the background equation-of-state parameter and the non-linear relation between the curvature and density perturbations.
More optimistically, if LIGO and Virgo has detected even one PBH, I will show that the reduction in pressure during the QCD transition naturally leads to an exponentially enhanced number of solar mass PBHs. Being below the Chandrasekhar mass, the detection of such light black holes would be a smoking gun for a primordial black hole. Finally, I will show that a mixed dark matter model with WIMPs and PBHs is already observationally excluded, unless the PBHs are at least one million times lighter than the sun.


Thu 02.05.2019, 16.30 h

G. Rodrigo (U. Valencia)



Thu 09.05.2019, 16.30 h

J. Pradler (HEPHY Wien)



Thu 16.05.2019, 16.30 h

J.-N. Lang (U. Zürich)



Thu 23.05.2019, 16.30 h

E. Sellentin (U. Genf)



Thu 06.06.2019, 16.30 h

M. Grazzini (U. Zürich)



Thu 27.06.2019, 16.30 h

A. Refregier (ETH Zürich)



Thu 04.07.2019, 16.30 h

C. White (Queen Mary London)



Thu 11.07.2019, 16.30 h

D. Malyshev (Erlangen)