Neutron stars are compact objects characterized by intense magnetic fields that influence the behaviour of radiation and matter with respect to normal conditions. Observations of X-ray emission from accreting neutron stars allow one to study these phenomena in conditions that are not reproducible in laboratory. According to current theoretical models, very strong magnetic fields can modify the polarization properties of radiation emitted from these objects, observed for the first time in the X-rays thanks to the IXPE satellite, launched in December 2021. Observations performed in different accreting X-ray pulsars made it possible to determine the geometry of the sources, but they revealed extremely low polarization degrees, in contrast to theoretical predictions. The purpose of this work is to briefly present theoretical models available so far and critically discuss the results of the recent IXPE observations.
Le stelle di neutroni sono oggetti compatti dotati di forti campi magnetici. Questi ultimi influenzano il comportamento di radiazione e materia rispetto alle condizioni normali. L'osservazione della radiazione X emessa da stelle di neutroni in accrescimento consente di studiare questi fenomeni in condizioni altrimenti non riproducibili in laboratori terrestri. Secondo gli attuali modelli teorici, campi magnetici molto intensi sono anche in grado di modificare le proprietà di polarizzazione della radiazione emessa da questi oggetti, per la prima volta osservabile nei raggi X grazie al lancio del satellite IXPE, nel Dicembre 2021. Le osservazioni effettuate finora su una serie di accreting X-ray pulsar hanno consentito di vincolare la geometria delle sorgenti, ma hanno rivelato gradi di polarizzazione estremamente bassi, al contrario di quanto previsto dalla teoria. L'obiettivo di questa tesi è quello di presentare brevemente i modelli teorici finora disponibili e discutere criticamente i risultati delle recenti osservazioni IXPE.
Misure polarimetriche in accreting X-ray pulsar
PAVAN, CATERINA
2023/2024
Abstract
Neutron stars are compact objects characterized by intense magnetic fields that influence the behaviour of radiation and matter with respect to normal conditions. Observations of X-ray emission from accreting neutron stars allow one to study these phenomena in conditions that are not reproducible in laboratory. According to current theoretical models, very strong magnetic fields can modify the polarization properties of radiation emitted from these objects, observed for the first time in the X-rays thanks to the IXPE satellite, launched in December 2021. Observations performed in different accreting X-ray pulsars made it possible to determine the geometry of the sources, but they revealed extremely low polarization degrees, in contrast to theoretical predictions. The purpose of this work is to briefly present theoretical models available so far and critically discuss the results of the recent IXPE observations.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/71948