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.
Anabella Araudo (Institute of Physics, Czech Academy of Sciences)
Fast Radio Bursts (FRBs) are transient episodes of intense, coherent radio emission lasting from microseconds to milliseconds. While the origin of FRBs remains uncertain, most are detected at extragalactic distances. Notably, the repeating FRB 200428 has been associated with the Galactic magnetar SGR 1935+2154. We propose a new model for FRB emission from SGR 1935+2154, where streaming instabilities in a baryon-loaded expanding fireball with different electron and ion temperatures forms density cavities filled with electrostatic fields. Using one-dimensional particle-in-cell kinetic simulations, we constrain the size of these plasma cavities and characterize the electrostatic fields. The resulting FRB emission originates from the coherent Bremsstrahlung of relativistic particle bunches accelerated within the cavities. Our model reproduces the observed radio fluxes of FRBs from SGR 1935+2154 with a small coherence parameter. The relationship between the wave coherence scale and the electric field amplitudes indicates that harmonic emission is several orders of magnitude weaker than the fundamental emission. Moreover, unlike previous models that attribute cavity formation to Langmuir collapse in pair plasmas, our results show that these structures can continue to generate ion acoustic waves after Langmuir saturation. Detecting harmonics in FRB observations, or placing upper limits on their luminosity, can help discriminate among emission mechanisms and constrain the electron–ion or electron–positron composition of magnetar environments during such events.
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).
Sreekanth Harikumar (NCAC, Warsaw)
Based on https://arxiv.org/abs/2510.27022 from LVK Collaboration (30 Oct 2025).
