Browsing by Author "Tak, D."

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    Fermi-LAT Observations of LIGO/Virgo Event GW170817
    (IOP Publishing, 2018) Ajello, M.; Allafort, A.; Axelsson, M.; Baldini, L.; Barbiellini, G.; Baring, M.G.; Bastieri, D.; Bellazzini, R.; Berenji, B.; Bissaldi, E.; Blandford, R.D.; Bloom, E.D.; Bonino, R.; Bottacini, E.; Brandt, T.J.; Bregeon, J.; Bruel, P.; Buehler, R.; Burnett, T.H.; Buson, S.; Cameron, R.A.; Caputo, R.; Caraveo, P.A.; Casandjian, J.M.; Cavazzuti, E.; Chekhtman, A.; Cheung, C.C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Cohen-Tanugi, J.; Cominsky, L.R.; Costantin, D.; Cuoco, A.; Cutini, S.; D’Ammando, F.; de Palma, F.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Dubois, R.; Dumora, D.; Favuzzi, C.; Ferrara, E.C.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Gill, R.; Giordano, F.; Giroletti, M.; Glanzman, T.; Granot, J.; Green, D.; Grenier, I.A.; Grondin, M.-H.; Guillemot, L.; Guiriec, S.; Harding, A.K.; Hays, E.; Horan, D.; Imazato, F.; Jóhannesson, G.; Kamae, T.; Kensei, S.; Kocevski, D.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Li, J.; Longo, F.; Loparco, F.; Lovellette, M.N.; Lubrano, P.; Magill, J.D.; Maldera, S.; Manfreda, A.; Mazziotta, M.N.; Michelson, P.F.; Mizuno, T.; Moiseev, A.A.; Monzani, M.E.; Moretti, E.; Morselli, A.; Moskalenko, I.V.; Negro, M.; Nuss, E.; Ojha, R.; Omodei, N.; Orlando, E.; Ormes, J.F.; Palatiello, M.; Paliya, V.S.; Paneque, D.; Persic, M.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Porter, T.A.; Principe, G.; Racusin, J.L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Ritz, S.; Rochester, L.S.; Ryde, F.; Parkinson, P.M. Saz; Sgrò, C.; Siskind, E.J.; Spada, F.; Spandre, G.; Spinelli, P.; Suson, D.J.; Tajima, H.; Takahashi, M.; Tak, D.; Thayer, J.G.; Thayer, J.B.; Torres, D.F.; Torresi, E.; Tosti, G.; Troja, E.; Valverde, J.; Venters, T.M.; Vianello, G.; Wood, K.; Yang, C.; Zaharijas, G.
    We present the Fermi Large Area Telescope (LAT) observations of the binary neutron star merger event GW170817 and the associated short gamma-ray burst (SGRB) GRB 170817A detected by the Fermi Gamma-ray Burst Monitor. The LAT was entering the South Atlantic Anomaly at the time of the LIGO/Virgo trigger (t GW) and therefore cannot place constraints on the existence of high-energy (E > 100 MeV) emission associated with the moment of binary coalescence. We focus instead on constraining high-energy emission on longer timescales. No candidate electromagnetic counterpart was detected by the LAT on timescales of minutes, hours, or days after the LIGO/Virgo detection. The resulting flux upper bound (at 95% C.L.) from the LAT is 4.5 × 10−10 erg cm−2 s−1 in the 0.1–1 GeV range covering a period from t GW + 1153 s to t GW + 2027 s. At the distance of GRB 170817A, this flux upper bound corresponds to a luminosity upper bound of 9.7 × 1043 erg s−1, which is five orders of magnitude less luminous than the only other LAT SGRB with known redshift, GRB 090510. We also discuss the prospects for LAT detection of electromagnetic counterparts to future gravitational-wave events from Advanced LIGO/Virgo in the context of GW170817/GRB 170817A.
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    Improving the Low-energy Transient Sensitivity of AMEGO-X using Single-site Events
    (IOP Publishing, 2022) Martinez-Castellanos, I.; Fleischhack, Henrike; Karwin, C.; Negro, M.; Tak, D.; Lien, Amy; Kierans, C. A.; Wadiasingh, Zorawar; Fukazawa, Yasushi; Ajello, Marco; Baring, Matthew G.; Burns, E.; Caputo, R.; Hartmann, Dieter H.; Perkins, Jeremy S.; Racusin, Judith L.; Sheng, Yong
    AMEGO-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.