Special Seminar：Probing the Early Universe and our own Galaxy with light particles

by Dr Luca Visinelli

Tuesday 26 Nov 2019, 10:30 → 11:30 Asia/Shanghai

5#/6th-603 - Meeting Room 603 (Science Building)

Abstract:

Axions and axion-like particles are excellent dark matter candidates, spanning a vast range of mass scales from the milli- and micro-eV for the QCD axion, to 10^(-22)eV for ultralight axions that make up the "axiverse". In some scenarios, the collapse of the non-homogeneous axion field leads to the formation of two kind of compact structures, known as axion "miniclusters" and axion "stars". I will first discuss astrophysical and cosmological constraints on axions at either end of this spectrum, using data from the cosmic microwave background anisotropies and the effects of miniclusters on the gravitational microlensing and on direct detection. I will anticipate some work in progress at GRAPPA on the new branch of "axion radio-astronomy" that involves neutron stars and axions. I will then assess the formation and the evolution of axion stars in various astrophysical regimes.

Biography:

2019 – Today

Researcher, GRAPPA Amsterdam (Netherlands)

Principal investigator: Prof. Christopher Weniger (GRAPPA Amsterdam) I am currently working on models linking the evolution of dark energy with Planck and supernovae data, aimed at easing the H0 tension. In continuation with my experience at Stockholm University, I am also working on particle astrophysics and leptogenesis.

2018 – 2019 Researcher, Uppsala University (Sweden)

Principal investigator: Prof. Ulf Danielsson (Uppsala University) I have worked on models linking the evolution of dark energy with Planck and supernovae data, aimed at easing the H0 tension.

2016 – 2018 Researcher, Stockholm University and Nordita (Sweden)

Principal investigator: Prof. Katherine Freese (U. of Michigan and Stockholm U.) I have worked on axion cosmology, the Higgs field as a spectator during inflation, capture of dark matter by massive bodies and by primordial black holes, modelling and evolution of dark stars with the MESA stellar code. Here is my interview at Stockholm University.

2013 – 2015 Postdoctoral Fellow, Mediterranean Center on Climate Changes (CMCC), Bologna (Italy) Principal investigators: Simona Masina (2013-2015), Marcello Vichi (2013-2014); I have developed a numerical code for assessing the global ocean carbon uptake, aiming to assess the global carbon flux within the GeoCarbon project http://www.geocarbon.net.