The gravitational lensing effect is the phenomenon for which the electromagnetic radiation, departing from a luminous object is deflected in the proximity of a mass distribution (the gravitational lens), placed between the source and an observer. In the relativistic interpretation, massive objects curve the space-time continuum and light rays, which follow this curvature, are bent passing close to these deflectors. Thus, a gravitational lens essentially acts on light as a normal lens does in geometrical optics. Precise modeling of massive galaxy clusters acting as lenses is crucial: it would help to disentangle the discrepancies emerging between the predictions of the cosmological concordance model and the observations at the scale of collapsed structures. The gravitational lens which is the subject of the present thesis is Abell 2163, one of the most massive galaxy clusters known, at redshift 0.2. Abell 2163 is a challenging system and a goldmine for contemporary astrophysics: its complex structure shows a variety of interacting sub-systems manifesting their activity all over the electromagnetic spectrum. A missing key element to unveil the properties of this cluster is to map its mass distribution at high resolution. We perform such a reconstruction thanks to the presence, in its core, of the typical effects of the strong gravitational lensing regime, such as the presence of multiple images produced from single background sources. Using data from the Multi Unit Spectroscopic Explorer on the VLT, in Chile, we compile and release three astronomical catalogs, confirm known multiple images and discover new lensed galaxies. We then build, test and rank different mass models, using Hubble Space Telescope data and the positions of the observed multiple images as constraints. Finally, we provide the most precise strong lensing mass model of the Abell 2163 core: the model- predicted positions of the multiple images are, on average, only 2.5 pixels away from the observed ones. The precise results of the present thesis can improve a number of scientific programs and can contribute significantly to different lines of research, e.g., the definition of the Abell 2163 merging history and an initial test on a possible self-interaction of the dark matter.

AN ACCURATE MASS MODEL OF THE GALAXY CLUSTER ABELL 2163 VIA STRONG GRAVITATIONAL LENSING / U. Rescigno ; supervisore: M. Lombardi ; co-supervisore: C. Grillo ; director of the school: M. Paris. DIPARTIMENTO DI FISICA "ALDO PONTREMOLI", 2019 Dec 20. 32. ciclo, Anno Accademico 2019. [10.13130/rescigno-umberto_phd2019-12-20].

AN ACCURATE MASS MODEL OF THE GALAXY CLUSTER ABELL 2163 VIA STRONG GRAVITATIONAL LENSING

U. Rescigno
2019

Abstract

The gravitational lensing effect is the phenomenon for which the electromagnetic radiation, departing from a luminous object is deflected in the proximity of a mass distribution (the gravitational lens), placed between the source and an observer. In the relativistic interpretation, massive objects curve the space-time continuum and light rays, which follow this curvature, are bent passing close to these deflectors. Thus, a gravitational lens essentially acts on light as a normal lens does in geometrical optics. Precise modeling of massive galaxy clusters acting as lenses is crucial: it would help to disentangle the discrepancies emerging between the predictions of the cosmological concordance model and the observations at the scale of collapsed structures. The gravitational lens which is the subject of the present thesis is Abell 2163, one of the most massive galaxy clusters known, at redshift 0.2. Abell 2163 is a challenging system and a goldmine for contemporary astrophysics: its complex structure shows a variety of interacting sub-systems manifesting their activity all over the electromagnetic spectrum. A missing key element to unveil the properties of this cluster is to map its mass distribution at high resolution. We perform such a reconstruction thanks to the presence, in its core, of the typical effects of the strong gravitational lensing regime, such as the presence of multiple images produced from single background sources. Using data from the Multi Unit Spectroscopic Explorer on the VLT, in Chile, we compile and release three astronomical catalogs, confirm known multiple images and discover new lensed galaxies. We then build, test and rank different mass models, using Hubble Space Telescope data and the positions of the observed multiple images as constraints. Finally, we provide the most precise strong lensing mass model of the Abell 2163 core: the model- predicted positions of the multiple images are, on average, only 2.5 pixels away from the observed ones. The precise results of the present thesis can improve a number of scientific programs and can contribute significantly to different lines of research, e.g., the definition of the Abell 2163 merging history and an initial test on a possible self-interaction of the dark matter.
20-dic-2019
Settore FIS/05 - Astronomia e Astrofisica
LOMBARDI, MARCO
PARIS, MATTEO
LOMBARDI, MARCO
GRILLO, CLAUDIO
Doctoral Thesis
AN ACCURATE MASS MODEL OF THE GALAXY CLUSTER ABELL 2163 VIA STRONG GRAVITATIONAL LENSING / U. Rescigno ; supervisore: M. Lombardi ; co-supervisore: C. Grillo ; director of the school: M. Paris. DIPARTIMENTO DI FISICA "ALDO PONTREMOLI", 2019 Dec 20. 32. ciclo, Anno Accademico 2019. [10.13130/rescigno-umberto_phd2019-12-20].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/697126
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