GRB 180128A: A Second Magnetar Giant Flare from the Sculptor Galaxy

Magnetars are a type of NS characterized by strong (10¹⁴−10¹⁵ G), short-lived (∼ 10⁴ yr) magnetic fields. They display a range of high energy electromagnetic activity. The brightest and most energetic of these events, with E_iso ≈ 10⁴⁴−10⁴⁶ erg, is the magnetar giant flare (MGF). To date only 7 such events have been discovered, 3 of which occurred in our Galactic neighborhood. Given that 3 occurred locally, and as all 7 identified MGFs are bright, there should be additional, weaker events in archival data. Therefore, a search of Fermi-GBM data was conducted. This led to the discovery of an 8th MGF. This new event is unique in several ways and we will discuss the implications.