F. J. Castander, B. Flaugher, Peter Doel, H. T. Diehl, Josh Frieman, Samuel Hinton, E. J. Sanchez, G. Gutierrez, I. Sevilla-Noarbe, N. Kuropatkin, T. N. Varga, L. N. da Costa, Peter Melchior, Douglas L. Tucker, Kyler Kuehn, Sunayana Bhargava, Huan Lin, M. E. C. Swanson, K. Honscheid, J. Carretero, F. Paz-Chinchón, V. Scarpine, Jennifer L. Marshall, M. Costanzi, Tim Eifler, Santiago Avila, Michael Schubnell, Lise Christensen, Antonella Palmese, G. Tarle, E. Buckley-Geer, G. Meylan, M. Smith, David J. James, Daniel Gruen, M. A. G. Maia, Marcelle Soares-Santos, S. Desai, Cristian Rusu, Felipe Menanteau, E. Bertin, S. Serrano, David J. Brooks, Pablo Fosalba, Tommaso Treu, J. Poh, Anowar J. Shajib, Michel Aguena, J. Gschwend, A. Carnero Rosell, S. Allam, Robert A. Gruendl, A. A. Plazas, E. Suchyta, Simon Birrer, A. Agnello, S. Everett, Ramon Miquel, Thomas E. Collett, R. L. C. Ogando, Christopher D. Fassnacht, Juan Garcia-Bellido, Kenneth C. Wong, M. Carrasco Kind, Sampath Mukherjee, Enrique Gaztanaga, Timo Anguita, J. De Vicente, 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, García-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, Serrano, S, Sevilla-Noarbe, I, Smith, M, Soares-Santos, M, Suchyta, E, Swanson, M E C, Tarle, G, Tucker, D L, Varga, T N, Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), DES, European Space Agency, National Aeronautics and Space Administration (US), European Research Council, European Commission, and Ministerio de Economía y Competitividad (España)
The DES Collaboration: et al., 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 per cent), 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 per cent, as long as no external shear constraints are imposed., JP would like to thank Gourav Khullar for his help and insightful discussions that helped improve the analysis in this paper. This work made use of computing resources and support provided by the Research Computing Center at the University of Chicago. JP is supported in part by the Kavli Institute for Cosmological Physics at the University of Chicago through grant NSF PHY-1125897 and an endowment from the Kavli Foundation and its founder Fred Kavli. AJS was supported by the National Aeronautics and Space Administration (NASA) through the Space Telescope Science Institute (STScI) grant HST-GO-15320. AJS was also supported by the Dissertation Year Fellowship from the University of California, Los Angeles (UCLA) graduate division. TA acknowledges support from Proyecto FONDECYT N: 1190335. This work was supported by World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan. CDF acknowledges support for this work from the National Science Foundation under Grant No. AST-1715611. SM acknowledges the funding from the European Research Council (ERC) under the EUs Horizon 2020 research and innovation program (COSMICLENS; grant agreement No. 787886). Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovação, the Deutsche Forschungsgemeinschaft and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenössische Technische Hochschule (ETH) Zürich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciències de l’Espai (IEEC/CSIC), the Institut de Física d’Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universität München and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, The Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, Texas A&M University, and the OzDES Membership Consortium. Based in part on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The DES data management system is supported by the National Science Foundation under Grant Numbers AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-88861, FPA2015-68048, SEV-2012-0234, SEV-2016-0597, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya. Research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Program (FP7/2007-2013) including ERC grant agreements 240672, 291329, and 306478. We acknowledge support from the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020. This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.