Second-order singular pertubative theory for gravitational lenses - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2018

Second-order singular pertubative theory for gravitational lenses

Résumé

The extension of the singular perturbative approach to the second order is presented in this paper. The general expansion to the second order is derived. The second-order expansion is considered as a small correction to the first-order expansion. Using this approach, it is demonstrated that in practice the second-order expansion is reducible to a first order expansion via a re-definition of the first-order pertubative fields. Even if in usual applications the second-order correction is small the reducibility of the second-order expansion to the first-order expansion indicates a potential degeneracy issue. In general, this degeneracy is hard to break. A useful and simple second-order approximation is the thin source approximation, which offers a direct estimation of the correction. The practical application of the corrections derived in this paper is illustrated by using an elliptical NFW lens model. The second-order pertubative expansion provides a noticeable improvement, even for the simplest case of thin source approximation. To conclude, it is clear that for accurate modelization of gravitational lenses using the perturbative method the second-order perturbative expansion should be considered. In particular, an evaluation of the degeneracy due to the second-order term should be performed, for which the thin source approximation is particularly useful.
Fichier principal
Vignette du fichier
stx3172.pdf (305.75 Ko) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

insu-03747709 , version 1 (08-08-2022)

Identifiants

Citer

C. Alard. Second-order singular pertubative theory for gravitational lenses. Monthly Notices of the Royal Astronomical Society, 2018, 475, pp.244-247. ⟨10.1093/mnras/stx3172⟩. ⟨insu-03747709⟩
12 Consultations
8 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More