Extreme amplification regimes of the Schwarzschild gravitational lens

0574635 - FZÚ 2024 RIV FR eng J - Journal Article
Bakala, P. - Bakalová, Alena - La Placa, R. - Falanga, M. - Stella, L.
Extreme amplification regimes of the Schwarzschild gravitational lens.
Astronomy & Astrophysics. Roč. 673, May (2023), č. článku A164. ISSN 0004-6361. E-ISSN 1432-0746
Institutional support: RVO:68378271
Keywords : gravitational lensing * strong * black hole physics * methods * analytical
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 6.5, year: 2022
Method of publishing: Open access

We investigated a complete set of relativistic images of a small source located at an arbitrary distance from a Schwarzschild black hole gravitational lens. This paper offers a description of a simple and efficient fully relativistic method for calculating the bolometric intensity amplification. We focused our analysis primarily on sources located at small radii and close angular distance from the caustic line, both behind and in front of the compact lens. We term the corresponding large deflection regime 'extreme lensing'. We approximated the regime of fully-relativistic, extreme amplification of point sources by simple analytical formulae valid over a wide range of source distances. Using such approximations, we also derived formulae for the maximum amplification of extended sources close to or intercepted by the caustic line. Simple analytical approximations of the time delay between the brightest consecutive images in extreme amplification regimes are also presented.
Permanent Link: https://hdl.handle.net/11104/0349076