Examinando por Autor "Abramson L.E."

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    Discovery of three strongly lensed quasars in the Sloan Digital Sky Survey
    (Oxford University Press, 2018-06) Williams P.R.; Agnello A.; Treu T.; Apostolovski Y.; Chen G.C.; Fassnacht C.D.; Hsueh J.W.; Lemaux B.C.; Motta V.; Oldham L.; Rojas K.; Rusu C.E.; Shajib A.J.; Wang X.; Abramson L.E.
    We present the discovery of three quasar lenses in the Sloan Digital Sky Survey, selected using two novel photometry-based selection techniques. The J0941+0518 system, with two point sources separated by 5.46 arcsec on either side of a galaxy, has source and lens redshifts 1.54 and 0.343. Images of J2257+2349 show two point sources separated by 1.67 arcsec on either side of an E/S0 galaxy. The extracted spectra show two images of the same quasar at zs = 2.10. SDSS J1640+1045 has two quasar spectra at zs = 1.70 and fits to the SDSS and Pan-STARRS images confirm the presence of a galaxy between the two point sources. We observed 56 photometrically selected lens candidates in this follow-up campaign, confirming three new lenses, re-discovering one known lens, and ruling out 36 candidates, with 16 still inconclusive. This initial campaign demonstrates the power of purely photometric selection techniques in finding lensed quasars. © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
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    The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2016 follow-up campaign - II. New quasar lenses from double component fitting
    (Oxford University Press, 2018-11) Anguita T.; Schechter P.L.; Kuropatkin N.; Morgan N.D.; Ostrovski F.; Abramson L.E.; Agnello A.; Apostolovski Y.; Fassnacht C.D.; Hsueh J.W.; Motta V.; Rojas K.; Rusu C.E.; Treu T.; Williams P.; Auger M.; Buckley-Geer E.; Lin H.; McMahon R.; Abbott T.M.C.; Allam S.; Annis J.; Bernstein R.A.; Bertin E.; Brooks D.; Burke D.L.; Carnero Rosell A.; Carrasco-Kind M.; Carretero J.; Cunha C.E.; D'Andrea C.B.; De Vicente J.; Depoy D.L.; Desai S.; DIehl H.T.; Doel P.; Flaugher B.; García-Bellido J.; Gerdes D.W.; Gschwend J.; Hartley W.G.; Hollowood D.L.; Honscheid K.; James D.J.; Kuehn K.; Lima M.; Maia M.A.G.; Miquel R.; Plazas A.A.; Sanchez E.; Scarpine V.; Smith M.; Soares-Santos M.; Sobreira F.; Suchyta E.; Tarle G.; Walker A.R.; Gruent, D.
    We report upon the follow-up of 34 candidate lensed quasars found in the Dark Energy Survey using NTT EFOSC, Magellan-IMACS, KECK-ESI, and SOAR-SAMI. These candidates were selected by a combination of double component fitting, morphological assessment, and colour analysis. Most systems followed up are indeed composed of at least one quasar image and 13 with two or more quasar images: two lenses, four projected binaries, and seven nearly identical quasar pairs (NIQs). The two systems confirmed as genuine gravitationally lensed quasars are one quadruple at $z$s = 1.713 and one double at $z$s = 1.515. Lens modelling of these two systems reveals that both systems require very little contribution from the environment to reproduce the image configuration. Nevertheless, small flux anomalies can be observed in one of the images of the quad. Further observations of nine inconclusive systems (including seven NIQs) will allow to confirm (or not) their gravitational lens nature. © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.