Browsing by Author "Negro, Michela"

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    GRB 180128A: A second magnetar giant flare candidate from the Sculptor Galaxy
    (EDP Sciences, 2024) Trigg, Aaron C.; Burns, Eric; Roberts, Oliver J.; Negro, Michela; Svinkin, Dmitry S.; Baring, Matthew G.; Wadiasingh, Zorawar; Christensen, Nelson L.; Andreoni, Igor; Briggs, Michael S.; Lalla, Niccolò Di; Frederiks, Dmitry D.; Lipunov, Vladimir M.; Omodei, Nicola; Ridnaia, Anna V.; Veres, Peter; Lysenko, Alexandra L.
    Magnetars are slowly rotating neutron stars that possess the strongest magnetic fields known in the cosmos (10 14 − 10 15 G). They display a range of transient high-energy electromagnetic activity. The brightest and most energetic of these events are the gamma-ray bursts (GRBs) known as magnetar giant flares (MGFs), with isotropic energies E iso ≈ 10 44 − 10 46 erg. Only seven MGF detections have been made to date: three unambiguous events occurred in our Galaxy and the Magellanic Clouds, and the other four MGF candidates are associated with nearby star-forming galaxies. As all seven identified MGFs are bright at Earth, additional weaker events likely remain unidentified in archival data. We conducted a search of the Fermi Gamma-ray Burst Monitor database for candidate extragalactic MGFs and, when possible, collected localization data from the Interplanetary Network (IPN) satellites. Our search yielded one convincing event, GRB 180128A. IPN localizes this burst within NGC 253, commonly known as the Sculptor Galaxy. The event is the second MGF in modern astronomy to be associated with this galaxy and the first time two bursts have been associated with a single galaxy outside our own. Here we detail the archival search criteria that uncovered this event and its spectral and temporal properties, which are consistent with expectations for a MGF. We also discuss the theoretical implications and finer burst structures resolved from various binning methods. Our analysis provides observational evidence of an eighth identified MGF.
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    The role of magnetar transient activity in time-domain and multimessenger astronomy
    (Frontiers Media S.A., 2024) Negro, Michela; Younes, George; Wadiasingh, Zorawar; Burns, Eric; Trigg, Aaron; Baring, Matthew
    Time-domain and multimessenger astronomy (TDAMM) involves the study of transient and time-variable phenomena across various wavelengths and messengers. The Astro2020 Decadal Survey has identified TDAMM as the top priority for NASA in this decade, emphasizing its crucial role in advancing our understanding of the universe and driving new discoveries in astrophysics. The TDAMM community has come together to provide further guidance to funding agencies, aiming to define a clear path toward optimizing scientific returns in this research domain. This encompasses not only astronomy but also fundamental physics, offering insights into properties of gravity, the formation of heavy elements, the equation of state of dense matter, and quantum effects associated with extreme magnetic fields. Magnetars, neutron stars with the strongest magnetic fields in the universe, play a critical role in this context. We aim to underscore the significance of magnetars in TDAMM, highlighting the necessity of ensuring observational continuity, addressing current limitations, and outlining essential requirements to expand our knowledge in this field.