Martinez-Castellanos, I.Fleischhack, HenrikeKarwin, C.Negro, M.Tak, D.Lien, AmyKierans, C. A.Wadiasingh, ZorawarFukazawa, YasushiAjello, MarcoBaring, Matthew G.Burns, E.Caputo, R.Hartmann, Dieter H.Perkins, Jeremy S.Racusin, Judith L.Sheng, Yong2022-09-012022-09-012022Martinez-Castellanos, I., Fleischhack, Henrike, Karwin, C., et al.. "Improving the Low-energy Transient Sensitivity of AMEGO-X using Single-site Events." <i>The Astrophysical Journal,</i> 934, no. 2 (2022) IOP Publishing: https://doi.org/10.3847/1538-4357/ac7ab2.https://hdl.handle.net/1911/113159AMEGO-X, the All-sky Medium Energy Gamma-ray Observatory eXplorer, is a proposed instrument designed to bridge the so-called "MeV gap" by surveying the sky with unprecedented sensitivity from ∼100 keV to about 1 GeV. This energy band is of key importance for multimessenger and multiwavelength studies but it is nevertheless currently underexplored. AMEGO-X addresses this situation by proposing a design capable of detecting and imaging gamma rays via both Compton interactions and pair production processes. However, some of the objects that AMEGO-X will study, such as gamma-ray bursts and magnetars, extend to energies below ∼100 keV where the dominant interaction becomes photoelectric absorption. These events deposit their energy in a single pixel of the detector. In this work we show how the ∼3500 cm2 effective area of the AMEGO-X tracker to events between ∼25 and ∼100 keV will be utilized to significantly improve its sensitivity and expand the energy range for transient phenomena. Although imaging is not possible for single-site events, we show how we will localize a transient source in the sky using their aggregate signal to within a few degrees. This technique will more than double the number of cosmological gamma-ray bursts seen by AMEGO-X, allow us to detect and resolve the pulsating tails of extragalactic magnetar giant flares, and increase the number of detected less-energetic magnetar bursts—some possibly associated with fast radio bursts. Overall, single-site events will increase the sensitive energy range, expand the science program, and promptly alert the community of fainter transient events.engOriginal content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Journal articleMartinez-Castellanos_2022_ApJ_934_92https://doi.org/10.3847/1538-4357/ac7ab2