Examinando por Autor "Frieman J."

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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.
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    STRIDES: Spectroscopic and photometric characterization of the environment and effects of mass along the line of sight to the gravitational lenses des J0408-5354 and WGD 2038-4008
    (Oxford University Press, 2020-11-01) Buckley-Geer E.J.; Lin H.; Rusu C.E.; Poh J.; Palmese A.; Agnello A.; Christensen L.; Frieman J.; Shajib A.J.; Treu T.; Collett T.; Birrer S.; Anguita T.; Fassnacht C.D.; Meylan G.; Mukherjee S.; Wong K.C.; Aguena M.; Allam S.; Avila S.; Bertin E.; Bhargava S.; Brooks D.; Carnero Rosell A.; Carrasco Kind M.; Carretero J.; Castander F.J.; Costanzi M.; Da Costa L.N.; De Vicente J.; Desai S.; Diehl H.T.; Doel P.; Eifler T.F.; Everett S.; Flaugher B.; Fosalba P.; Garciá-Bellido J.; Gaztanaga E.; Gruen D.; Gruendl R.A.; Gschwend J.; Gutierrez G.; Hinton S.R.; Honscheid K.; James D.J.; Kuehn K.; Kuropatkin N.; Maia M.A.G.; Marshall J.L.; Melchior P.; Menanteau F.; Miquel R.; Ogando R.L.C.; Paz-Chinchón F.; Plazas A.A.; Sanchez E.; Scarpine V.; Schubnell M.
    In time-delay cosmography, three of the key ingredients are (1) determining the velocity dispersion of the lensing galaxy, (2) identifying galaxies and groups along the line of sight with sufficient proximity and mass to be included in the mass model, and (3) estimating the external convergence κext from less massive structures that are not included in the mass model. We present results on all three of these ingredients for two time-delay lensed quad quasar systems, DES J0408-5354 and WGD 2038-4008. We use the Gemini, Magellan, and VLT telescopes to obtain spectra to both measure the stellar velocity dispersions of the main lensing galaxies and to identify the line-of-sight galaxies in these systems. Next, we identify 10 groups in DES J0408-5354 and two groups in WGD 2038-4008 using a group-finding algorithm. We then identify the most significant galaxy and galaxy-group perturbers using the 'flexion shift' criterion. We determine the probability distribution function of the external convergence κext for both of these systems based on our spectroscopy and on the DES-only multiband wide-field observations. Using weighted galaxy counts, calibrated based on the Millennium Simulation, we find that DES J0408-5354 is located in a significantly underdense environment, leading to a tight (width ∼ 3%), negative-value κext distribution. On the other hand, WGD 2038-4008 is located in an environment of close to unit density, and its low source redshift results in a much tighter κext of ~1%, as long as no external shear constraints are imposed.