Examinando por Autor "Sherman N."

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    Constraints on the Physical Properties of GW190814 through Simulations Based on DECam Follow-up Observations by the Dark Energy Survey
    (IOP Publishing Ltd, 2020-09) Morgan R.; Soares-Santos M.; Annis J.; Herner K.; Garcia A.; Palmese A.; Drlica-Wagner A.; Kessler R.; Garciá-Bellido J.; Bachmann T.G.; Sherman N.; Allam S.
    On 2019 August 14, the LIGO and Virgo Collaborations detected gravitational waves from a black hole and a 2.6 solar mass compact object, possibly the first neutron star-black hole merger. In search of an optical counterpart, the Dark Energy Survey (DES) obtained deep imaging of the entire 90% confidence level localization area with Blanco/DECam 0, 1, 2, 3, 6, and 16 nights after the merger. Objects with varying brightness were detected by the DES Pipeline, and we systematically reduced the candidate counterparts through catalog matching, light-curve properties, host-galaxy photometric redshifts, Southern Astrophysical Research spectroscopic follow-up observations, and machine-learning-based photometric classification. All candidates were rejected as counterparts to the merger. To quantify the sensitivity of our search, we applied our selection criteria to full light-curve simulations of supernovae and kilonovae as they would appear in the DECam observations. Because the source class of the merger was uncertain, we utilized an agnostic, three-component kilonova model based on tidally disrupted neutron star (NS) ejecta properties to quantify our detection efficiency of a counterpart if the merger included an NS. We find that, if a kilonova occurred during this merger, configurations where the ejected matter is greater than 0.07 solar masses, has lanthanide abundance less than 10-8.56, and has a velocity between 0.18c and 0.21c are disfavored at the 2σ level. Furthermore, we estimate that our background reduction methods are capable of associating gravitational wave signals with a detected electromagnetic counterpart at the 4σ level in 95% of future follow-up observations. © 2020 The American Astronomical Society. All rights reserved.
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    Designing an Optimal Kilonova Search Using DECam for Gravitational-wave Events
    (Institute of Physics, 2024-02) Bom C.R.; Annis J.; Garcia A.; Palmese A.; Sherman N.; Soares-Santos M.; Santana-Silva L.; Morgan R.; Bechtol K.; Davis T.; Diehl H.T.; Allam S.S.; Bachmann T.G.; Fraga B.M.O.; García-Bellido J.; Gill M.S.S.; Herner K.; Kilpatrick C.D.; Makler M.; Olivares E. F.; Pereira M.E.S.; Pineda J.; Santos A.; Tucker D.L.; Wiesner M.P.; Aguena M.; Alves O.; Bacon D.; Bernardinelli P.H.; Bertin E.; Bocquet S.; Brooks D.; Carrasco Kind M.; Carretero J.; Conselice C.; Costanzi M.; da Costa L.N.; De Vicente J.; Desai S.; Doel P.; Everett S.; Ferrero I.; Frieman J.; Gatti M.; Gerdes D.W.; Gruen D.; Gruendl R.A.; Gutierrez G.; Hinton S.R.; Hollowood D.L.; Honscheid K.; James D.J.; Kuehn K.; Kuropatkin N.; Melchior P.; Mena-Fernández J.; Menanteau F.; Pieres A.; Plazas Malagón A.A.; Raveri M.; Rodriguez-Monroy M.; Sanchez E.; Santiago B.; Sevilla-Noarbe I.; Smith M.; Suchyta E.; Swanson M.E.C.; Tarle G.; To C.; Weaverdyck N.
    We address the problem of optimally identifying all kilonovae detected via gravitational-wave emission in the upcoming LIGO/Virgo/KAGRA observing run, O4, which is expected to be sensitive to a factor of ∼7 more binary neutron star (BNS) alerts than previously. Electromagnetic follow-up of all but the brightest of these new events will require >1 m telescopes, for which limited time is available. We present an optimized observing strategy for the DECam during O4. We base our study on simulations of gravitational-wave events expected for O4 and wide-prior kilonova simulations. We derive the detectabilities of events for realistic observing conditions. We optimize our strategy for confirming a kilonova while minimizing telescope time. For a wide range of kilonova parameters, corresponding to a fainter kilonova compared to GW170817/AT 2017gfo, we find that, with this optimal strategy, the discovery probability for electromagnetic counterparts with the DECam is ∼80% at the nominal BNS gravitational-wave detection limit for O4 (190 Mpc), which corresponds to an ∼30% improvement compared to the strategy adopted during the previous observing run. For more distant events (∼330 Mpc), we reach an ∼60% probability of detection, a factor of ∼2 increase. For a brighter kilonova model dominated by the blue component that reproduces the observations of GW170817/AT 2017gfo, we find that we can reach ∼90% probability of detection out to 330 Mpc, representing an increase of ∼20%, while also reducing the total telescope time required to follow up events by ∼20%. © 2024. The Author(s). Published by the American Astronomical Society.