Astronomy & Astrophysics Seminar: Electromagnetic Fireworks: Fast Radio Bursts from Rapid Reconnection in the Compressed Magnetar Wind

Zoom: https://tau-ac-il.zoom.us/j/89636068691?pwd=YkVoWG9laTFPZHVENWovQ1FWczUvQT09

Abstract:

Fast radio bursts (FRBs) are extremely bright, short duration (few ms) radio pulses observed in the frequency range 0.1 -10 GHz at inferred cosmological distances. Their origin is yet unknown, however, the recent detection of an intense FRB from a Galactic magnetar has lent support to the hypothesis that at least some FRBs (notably the subclass of repeaters) are produced by magnetars. Following a brief overview of key observations, I'll discuss a scenario in which the observed bursts are produced by magnetic reconnection in a current sheet of the magnetar wind, upon compression by a strong magnetic pulse induced by a magnetar flare. In agreement with analytical estimates, we find, using 2D radiative PIC simulations, that magnetic pulses of 10^47 erg/s  can trigger relatively  narrow-band GHz emission with luminosities of approximately 10^43 erg/s, sufficient to explain the brightest extragalactic fast radio bursts. The mechanism provides a natural explanation for a downward frequency drift of burst signals (so-called, sad trombone effect), as well as the ~100 nanosecond sub-structure recently detected in FRB 20200120E.
 

Seminar Organizer: Dr. Iair Arcavi