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28 March 2022
Article (Scientific journals)
TDCOSMO. VII. Boxyness/discyness in lensing galaxies : Detectability and impact on $H_0$
Van de Vyvere, Lyne  ; Gomer, Matthew  ; Sluse, Dominique  et al.
2022 • In Astronomy and Astrophysics, 659, p. 127
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Keywords :
astro-ph.CO; astro-ph.GA
Abstract :
[en] In the context of gravitational lensing, the density profile of lensing galaxies is often considered to be perfectly elliptical. Potential angular structures are generally ignored, except to explain flux ratios anomalies. Surprisingly, the impact of azimuthal structures on extended images of the source has not been characterized, nor its impact on the H0 inference. We address this task by creating mock images of a point source embedded in an extended source, lensed by an elliptical galaxy on which multipolar components are added to emulate boxy/discy isodensity contours. Modeling such images with a density profile free of angular structure allow us to explore the detectability of image deformation induced by the multipoles in the residual frame. Multipole deformations are almost always detectable for our highest signal-to-noise mock data. However the detectability depends on the lens ellipticity and Einstein radius, on the S/N of the data, and on the specific lens modeling strategy. Multipoles also introduce small changes to the time delays. We therefore quantify how undetected multipoles would impact H0 inference. When no multipoles are detected in the residuals, the impact on H0 for a given lens is in general less than a few km/s/Mpc, but in the worst case scenario, combining low S/N in the ring and large intrinsic boxyness/discyness, the bias on H0 can reach 10-12 km/s/Mpc. If we now look at the inference on H0 from a population of lensing galaxies, having a distribution of multipoles representative of what is found in the light-profile of elliptical galaxies, we then find a systematic bias on H0 < 1%. The comparison of our mock systems to the state-of-the-art time delay lens sample studied by the H0LiCOW and TDCOSMO collaborations, indicates that multipoles are currently unlikely to be a source of substantial systematic bias on the inferred value of H0 from time-delay lenses.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Van de Vyvere, Lyne  ;  Université de Liège - ULiège > Unités de recherche interfacultaires > Space sciences, Technologies and Astrophysics Research (STAR)
Gomer, Matthew ;  Université de Liège - ULiège > Unités de recherche interfacultaires > Space sciences, Technologies and Astrophysics Research (STAR)
Sluse, Dominique  ;  Université de Liège - ULiège > Unités de recherche interfacultaires > Space sciences, Technologies and Astrophysics Research (STAR)
Xu, Dandan
Birrer, Simon
Galan, Aymeric
Vernardos, Georgios
Language :
English
Title :
TDCOSMO. VII. Boxyness/discyness in lensing galaxies : Detectability and impact on $H_0$
Publication date :
18 March 2022
Journal title :
Astronomy and Astrophysics
ISSN :
0004-6361
eISSN :
1432-0746
Publisher :
EDP Sciences
Volume :
659
Pages :
A127
Peer reviewed :
Peer Reviewed verified by ORBi
European Projects :
H2020 - 787886 - COSMICLENS - Cosmology with Strong Gravitational Lensing
Funders :
European Research Council
Swiss National Science Foundation
Tsinghua University Initiative Scientific Research Program
Chinese Academy of Sciences
Marie Sklodovska-Curie
Commentary :
Accepted for publication in A&A ; link to the notebook associated https://github.com/TDCOSMO/TD_data_public

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