Query : 2022A&A...659A.127V

2022A&A...659A.127V - Astronomy and Astrophysics, volume 659A, 127-127 (2022/3-1)

TDCOSMO. VII. Boxyness/discyness in lensing galaxies: Detectability and impact on H0.


Abstract (from CDS):

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 of point-like sources (i.e. flux ratio anomalies). Surprisingly, the impact of azimuthal structures on extended images of the source has not been characterised, nor has its impact on the H0 inference. We address this task by creating mock images of a point source embedded in an extended source and lensed by an elliptical galaxy on which multipolar components are added to emulate boxy or discy isodensity contours. Modelling such images with a density profile free of angular structure allows 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 ratio (S/N) 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 modelling 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–1 Mpc–1, but in the worst-case scenario, combining low S/N in the ring and large intrinsic boxyness or discyness, the bias on H0 can reach 10-12 km s–1 Mpc–1. If we now look at the inference on H0 from a population of lensing galaxies with a distribution of multipoles representative of what is found in the light profile of elliptical galaxies, we find a systematic bias on H0 of less than 1%. A 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.

Abstract Copyright: © ESO 2022

Journal keyword(s): gravitational lensing: strong - cosmological parameters - galaxies: structure

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 4C 05.19 QSO 04 14 37.76734974 +05 34 42.3295956   24.100 23.800 21.270   ~ 354 2
2 [VV2006] J043814.8-122314 QSO 04 38 14.88 -12 17 14.6     17.15     ~ 215 2
3 QSO J0924+0219 QSO 09 24 55.8048 +02 19 24.850   18.58 18.36     ~ 131 1
4 QSO B1115+080A QSO 11 18 16.951 +07 45 58.23   16.61 16.44     ~ 676 2
5 QSO J1131-1231 QSO 11 31 51.5387 -12 31 58.716           ~ 263 1
6 NGC 4697 GiG 12 48 35.8981498824 -05 48 02.482374564   10.97   9.83   ~ 853 0
7 NVSS J160914+653229 rG 16 09 13.96 +65 32 28.8     19.4     ~ 205 1
8 BWE 1938+6641 gLe 19 38 25.32029 +66 48 53.4199           ~ 101 2

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