Mysterious structures in our Galaxy obscuring the view towards the first stars in the Universe

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Speaker :  
Dr. Vibor Jelic (ASTRON, The Netherlands)
Location :  
2nd Floor Seminar Room
Date :  

Time : 

Abstract :

Recent LOFAR (Low Frequency Array) observations revealed a bewildering variety of structures in polarisation in several fields at high Galactic latitudes. The structures are found at different Faraday depths, which measures the product between the electron density of the ionized gas and the line-of-sight magnetic field. One of the fields, 3C196 field, shows the most interesting features. Notably, a few degrees straight filament, which displaces in Faraday depth the background synchrotron emission. While its physical parameters are hard to pinpoint, this is likely a filament of ionized gas located somewhere within the local bubble. Together with another structure observed in the same field it correlates with observed HI filaments and the magnetic field orientation probed by the Planck observations of the dust emission in polarisation. This result is quite surprising as LOFAR, Planck and HI observations are sensitive to different ISM phases. In addition, there is a conspicuous system of long and straight depolarisation canals aligned with the magnetic field. During my talk I will present and discuss these intriguing results, as well as, how they might obscure the view towards the first stars in the Universe - the LOFAR-Epoch of Reionization key science project.