Speaker
Description
The search for beyond the standard model physics with gamma-ray telescopes has traditionally been dominated by searches that leverage the extreme astrophysical environments of high-energy sources. These include searches for unexpected signal deviations (i.e., photon absorption or delay) and/or searches for predictable features (i.e., excesses from dark matter decay/annihilation). Both methods rely solely on studying the small sample of events collected by these telescopes that resemble gamma-ray air showers, discarding potentially interesting air shower images simply because they do not resemble single-photon-induced showers.
Imaging Atmospheric Cherenkov Telescopes (IACTs), such as VERITAS, provide an alternative avenue, utilizing the images of air showers to search not for gamma rays or cosmic rays, but for new particles and/or a unique combination of particles that would normally be removed during standard event selection. Since beginning operations in 2007, VERITAS has measured over 1 billion events, creating a rich dataset for these "rare event" searches. In this talk, we will present the results from such a search, one that is looking for "ultra-short gamma-ray bursts" (UGRBs). UGRBs are theoretical narrow pulses of gamma rays occurring for less than a microsecond. They could originate from pulsars, as fast radio burst counterparts, or as counterparts to macroscopic dark matter interactions. With a sufficient fluence, multiple gamma-rays from a UGRB are expected to produce overlapping air showers. These "wavefront" events provide unique images with features unseen in other air showers. We will present a series of realistic wavefront simulations and demonstrate how IACTs can practically search for such events in pre-existing datasets. Further, we will demonstrate how this time-domain based search performs on real VERITAS data, presenting the first results from a modern search. We will also discuss the potential for future rare event searches with next generation IACTs like LACT and CTAO.
