Examinando por Autor "Marshall, P.J."

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    COSMOGRAIL: XVII. Time delays for the quadruply imaged quasar PG 1115+080
    (EDP Sciences, 2018-08) Bonvin, V.; Chan, J.H.H.; Millon, M.; Rojas, K.; Courbin, F.; Chen, G.C.-F.; Fassnacht, C.D.; Paic, E.; Tewes, M.; Chao, D.C.-Y.; Chijani, M.; Gilman, D.; Gilmore, K.; Williams, P.; Buckley-Geer, E.; Frieman, J.; Marshall, P.J.; Suyu, S.H.; Treu, T.; Hempel, A.; Kim, S.; Lachaume, R.; Rabus, M.; Anguita, T.; Meylan, G.; Motta, V.; Magain, P.
    We present time-delay estimates for the quadruply imaged quasar PG 1115+080. Our results are based on almost daily observations for seven months at the ESO MPIA 2.2 m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per quasar image. In addition, we re-analyze existing light curves from the literature that we complete with an additional three seasons of monitoring with the Mercator telescope at La Palma Observatory. When exploring the possible source of bias we considered the so-called microlensing time delay, a potential source of systematic error so far never directly accounted for in previous time-delay publications. In 15 yr of data on PG 1115+080, we find no strong evidence of microlensing time delay. Therefore not accounting for this effect, our time-delay estimates on the individual data sets are in good agreement with each other and with the literature. Combining the data sets, we obtain the most precise time-delay estimates to date on PG 1115+080, with Δt(AB) = 8.3+1.5 -1.6 days (18.7% precision), Δt(AC) = 9.9+1.1 -1.1 days (11.1%) and Δt(BC) = 18.8+1.6 -1.6 days (8.5%). Turning these time delays into cosmological constraints is done in a companion paper that makes use of ground-based Adaptive Optics (AO) with the Keck telescope. © ESO 2018.
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    DES meets Gaia: Discovery of strongly lensed quasars from a multiplet search
    (Oxford University Press, 2018-10) Agnello, A.; Lin, H.; Kuropatkin, N.; Buckley-Geer, E.; Anguita, T.; Schechter, P.L.; Morishita, T.; Motta, V.; Rojas, K.; Treu, T.; Amara, A.; Auger, M.W.; Courbin, F.; Fassnacht, C.D.; Frieman, J.; More, A.; Marshall, P.J.; McMahon, R.G.; Meylan, G.; Suyu, S.H.; Glazebrook, K.; Morgan, N.; Nord, B.; Abbott, T.M.C.; Abdalla, F.B.; Annis, J.; Bechtol, K.; Benoit-Lévy, K.; Bertin, E.; Bernstein, R.A.; Brooks, D.; Burke, D.L.; Carnero Rosell, A.; Carretero, J.; Cunha, C.E.; D'Andrea, C.B.; da Costa, L.N.; Desai, S.; Drlica-Wagner, A.; Eifler, T.F.; Flaugher, B.; García-Bellido, J.; Gaztanaga, E.; Gerdes, D.W.; Gruen, D.; Gruendl, R.A.; Gschwend, J.; Gutierrez, G.; Honscheid, K.; James, D.J.; Kuehn, K.; Lahav, O.; Lima, M.; Maia, M.A.G.; March, M.; Menanteau, F.; Miquel, R.; Ogando, R.L.C.; Plazas, A.A.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M.E.C.; Tarle, G.; Tucker, D.; Wechsler, R.
    We report the discovery, spectroscopic confirmation, and first lens models of the first, strongly lensed quasars from a combined search in WISE and Gaia-DR1 over the DES footprint. Their Einstein radii span a range between ≈2.0 arcsec and ≈0.4 arcsec. Two of these (WGD2038-4008, RA = 20:38:02.65, Dec.=-40:08:14.64; WGD2021-4115, RA = 20:21:39.45, Dec. = -41:15:57.11) also have confirmed deflector redshifts. The four-image lens WGD2038-4008, with source and deflector redshifts s = 0.777 ± 0.001 and zl = 0.230 ± 0.002, respectively, has a deflector with radius Reff ≈ 3.4 arcsec, stellar mass log(M*/M⊙) = 11.64+0.20 -0.43, and extended isophotal shape variation. Simple lens models yield Einstein radii RE = (1.30 ± 0.04) arcsec, axis ratio q = 0.75 ± 0.1 (compatible with that of the starlight) and considerable shear-ellipticity degeneracies. The two-image lens WGD2021-4115 has zs = 1.390 ± 0.001 and zl = 0.335 ± 0.002, and Einstein radius RE = (1.1 ± 0.1) arcsec, but higher-resolution imaging is needed to accurately separate the deflector and faint quasar image. Analogous lens model degeneracies hold for the other six lenses (J0146-1133, J0150-4041, J0235-2433, J0245-0556, J0259-2338, and J0508-2748) shown in this paper. © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
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    TDCOSMO: II. Six new time delays in lensed quasars from high-cadence monitoring at the MPIA 2.2 m telescope
    (EDP Sciences, 2020-10) Millon., M.; Courbin, F.; Bonvin, V.; Buckley-Geer, E.; Fassnacht, C.D.; Frieman, J.; Marshall, P.J.; Suyu, S.H.; Treu, T.; Anguita, T.; Motta, V.; Agnello, A.
    We present six new time-delay measurements obtained from Rc-band monitoring data acquired at the Max Planck Institute for Astrophysics (MPIA) 2.2 m telescope at La Silla observatory between October 2016 and February 2020. The lensed quasars HE 0047-1756, WG 0214-2105, DES 0407-5006, 2M 1134-2103, PSJ 1606-2333, and DES 2325-5229 were observed almost daily at high signal-to-noise ratio to obtain high-quality light curves where we can record fast and small-amplitude variations of the quasars. We measured time delays between all pairs of multiple images with only one or two seasons of monitoring with the exception of the time delays relative to image D of PSJ 1606-2333. The most precise estimate was obtained for the delay between image A and image B of DES 0407-5006, where τAB = -128.4-3.8+3.5 d (2.8% precision) including systematics due to extrinsic variability in the light curves. For HE 0047-1756, we combined our high-cadence data with measurements from decade-long light curves from previous COSMOGRAIL campaigns, and reach a precision of 0.9 d on the final measurement. The present work demonstrates the feasibility of measuring time delays in lensed quasars in only one or two seasons, provided high signal-to-noise ratio data are obtained at a cadence close to daily. © 2020 ESO.
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    The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2016 follow-up campaign - I. Overview and classification of candidates selected by two techniques
    (Oxford University Press, 2018-11) Treu, T.; Agnello, A.; Baumer, M.A.; Birrer, S.; Buckley-Geer, E.J.; Courbin, F.; Kim, Y.J.; Lin, H.; Marshall, P.J.; Nord, B.; Schechter, P.L.; Sivakumar, P.R.; Abramson, L.E.; Anguita, T.; Apostolovski, Y.; Auger, M.W.; Chan, J.; Chen, G.; Collett, T.E.; Fassnacht, C.D.; Hsueh, J.-W.; Lemon, C.; McMahon, R.G.; Motta, V.; Ostrovski, F.; Rojas, K.; Rusu, C.E.; Williams, P.; Frieman, J.; Meylan, G.; Suyu, S.H.; Abbott, T.M.C.; Abdalla, F.B.; Allam, S.; Annis, J.; Avila, S.; Banerji, M.; Brooks, D.; Rosell, A.C.; Carrasco Kind, M.; Carretero, J.; Castander, F.J.; D'Andrea, C.B.; da Costa, L.N.; De Vicente, J.; Doel, P.; Eifler, T.F.; Flaugher, B.; Fosalba, P.; García-Bellido, J.; Goldstein, D.A.; Gruen, D.; Gruendl, R.A.; Gutierrez, G.; Hartley, W.G.; Hollowood, D.; Honscheid, K.; James, D.J.; Kuehn, K.; Kuropatkin, N.; Lima, M.; Maia, M.A.G.; Martini, P.; Menanteau, F.; Miquel, R.; Plazas, A.A.; Romer, A.K.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Smith, R.C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M.E.C.; Tarle, G.; Thomas, D.; Tucker, D.L.; Walker, A.R.
    The primary goals of the STRong lensing Insights into the Dark Energy Survey (STRIDES) collaboration are to measure the dark energy equation of state parameter and the free streaming length of dark matter. To this aim, STRIDES is discovering strongly lensed quasars in the imaging data of the Dark Energy Survey and following them up to measure time delays, high resolution imaging, and spectroscopy sufficient to construct accurate lens models. In this paper, we first present forecasts for STRIDES. Then, we describe the STRIDES classification scheme, and give an overview of the Fall 2016 follow-up campaign. We continue by detailing the results of two selection methods, the outlier selection technique and a morphological algorithm, and presenting lens models of a system that could possibly be a lensed quasar in an unusual configuration. We conclude with the summary statistics of the Fall 2016 campaign. Including searches presented in companion papers (Anguita et al.; Ostrovski et al.), STRIDES followed up 117 targets identifying 7 new strongly lensed systems, and 7 nearly identical quasars, which could be confirmed as lenses by the detection of the lens galaxy. 76 candidates were rejected and 27 remain otherwise inconclusive, for a success rate in the range of 6-35 per cent. This rate is comparable to that of previous searches like SDSS Quasar Lens Search even though the parent data set of STRIDES is purely photometric and our selection of candidates cannot rely on spectroscopic information. © 2018 The Author(s).