- evn2024@mpifr.de
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Contribution
Latest constraints on dark matter from strong gravitational lensing VLBI observations
Content
The Cold Dark Matter (CDM) model for structure formation is currently the most successful at reproducing many observations, but it remains largely untested in the non-linear sub-galactic regime. A clear prediction of this model is that a significant number of low-mass haloes should populate any galaxy and its line of sight. As most of these objects are expected to be completely dark, strong gravitational lensing provides a unique channel to detect them and determine the properties of dark matter by constraining the halo-mass function at the low-mass end.
The sensitivity of strong lensing observations to the presence of low-mass haloes strongly depends on the angular resolution of the data. At present, only VLBI observations at cm-wavelength provide us with the milli-arcseconds resolution needed to probe the halo mass function in the regime of 106 Msun, where predictions from different dark models differ the most. In this talk, I will discuss the latest constraints on FDM and CDM from existing VLBI observations. In particular, I will present the first detection of a 106 Msun low-mass halo and discuss its implications for CDM and WDM models. I will then provide some insights into what we could expect from future observing facilities such as the SKA and the ngVLA.