Sistemas binários resolvidos espectroscopicamente e astrometricamente como um teste de teorias de gravitação

Abstract

The proposition of the dark matter hypothesis was a milestone in understanding the structure and evolution of the Universe. Throughout history, astronomical observations have revealed that the amount of visible matter is not enough to explain the dynamics of galaxies and the rotation curves of spiral galaxies. This has led to the emergence of different theories of gravitation that seek to provide an explanation for this phenomenon. One of the most prominent theories is the Modified Newtonian Dynamics (MOND), which proposes a modification of Newton’s law of gravitation in the low acceleration regimes (a ≈ 1.2 × 10−10m/s2). MOND has been widely studied and tested as an alternative to the dark matter hypothesis, raising questions about its validity and limitations. One way to test theories of gravitation, including MOND, is through the study of resolved spectroscopic and astrometric binary systems, known as wide binaries. These systems consist of two stars that are sufficiently distant from each other, allowing their orbits and gravitational interactions to be observed and analyzed. In this dissertation, a detailed study of wide binaries was conducted as a test for theories of gravitation, with a focus on MOND. To obtain a study with the best data available so far, data obtained by the Gaia mission and the HARPS spectrograph were used, providing precise information about angular separation, spatial velocity, radial velocity, among other properties of these binary systems. Careful analyses of the properties of binary systems, combined with Gaia and HARPS data, allowed for a rigorous assessment of gravitation theories and their performance in explaining observations. The results obtained, although preliminary due to the still limited size of the sample, provided valuable information about the validity of MOND, the dark matter theory, and their ability to explain the dynamics of wide binaries, as well as the analogous problem of rotation curves of spiral galaxies.