The Colloquium takes place every Wednesday at 11:15 AM - Warsaw Copernicus Astronomical Centre online by means of Zoom platform. The Colloquium is given in English and chaired by dr Stanisław Bajtlik (bajtlik@camk.edu.pl). People from outside of the Copernicus Center are very welcome to participate. For technical detailes please contact Dr. Stanislaw Bajtlik.
Maciek Wielgus (Instituto de Astrofisica de Andalucia, Granada, Spain)
Very long baseline interferometry (VLBI) offers a way to study AGN jets with an exceptionally high angular resolution, zooming into the zone of the jet collimation and acceleration. In particular, a global array of the Event Horizon Telescope (EHT) offers unprecedented resolution with highest VLBI observing frequency of 230 GHz. During the first observing campaign of the EHT in 2017, observations of 16 AGN sources were carried out. Together with the previous measurements at lower radio frequencies, these new observations allow for a statistical study of the properties of AGN cores across the angular scales. We observe a persistent and statistically significant effect of brightness temperature increase with the distance from the central black hole, which indicates evolution of Doppler factors in accelerating jets and a gradual conversion of the magnetic energy into kinetic energy. I will describe these observations and discuss what they teach us about the AGN jets.
Journal Club takes place on Mondays at 11:15 AM in the Seminar Room. The presentation is given in English and is chaired by Journal Club Coordinators. Anyone interested in giving a Journal Club talk is encouraged to contact the email: journalclub(@camk.edu.pl).
Angelos Karakonstantakis (NCAC, Warsaw)
