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

Buckley-Geer, E J and Lin, H. and Rusu, C E and Desai, Shantanu et. al. (2020) 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. Monthly Notices of the Royal Astronomical Society, 498 (3). pp. 3241-3274. ISSN 0035-8711

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Abstract

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.

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IITH Creators:
IITH CreatorsORCiD
Desai, Shantanuhttp://orcid.org/0000-0002-0466-3288
Item Type: Article
Uncontrolled Keywords: galaxies: groups: general, gravitational lensing: strong, quasars: individual: DES J0408-5354, WGD 2038-4008
Subjects: Physics
Physics > Astronomy Astrophysics
Divisions: Department of Physics
Depositing User: . LibTrainee 2021
Date Deposited: 31 May 2021 07:56
Last Modified: 31 May 2021 07:56
URI: http://raiith.iith.ac.in/id/eprint/7893
Publisher URL: https://doi.org/10.1093/mnras/staa2563
OA policy: https://v2.sherpa.ac.uk/id/publication/24618
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