High-energy observations of CHIME fast radio bursts

The origin of Fast Radio Bursts (FRBs) remains a mystery even as we are collecting important signs that point towards preferred source models. A key piece of the puzzle is the search for their multiwavelength counterparts. The detection of an FRB-like event from the Galactic magnetar SGR 1935+2154 with a simultaneous X-ray burst points to a magnetar origin for some FRBs, and such magnetar high-energy bursts may be detectable from nearby FRB sources. I will present the results of three different studies probing for high-energy counterparts of FRBs in complementary ways: Deep limits from XMM-Newton, Chandra, NuSTAR, and NICER at the time of Effelsberg radio bursts from the most nearby FRB source, FRB 20200120E, located in a M81 globular cluster; deep CHIME+NICER observations of the most active FRB source, FRB 20220912A; and limits from Swift BAT GUANO on prompt gamma-ray counterparts at the time of hundreds of FRBs detected by CHIME. I will then discuss what these three and other high-energy limits can tell us about the nature of FRBs.