Campostrini, Stefano (2018) Determinazione della massa del buco nero centrale della galassia a spirale NGC 3259. [Laurea triennale]
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According to the current paradigm there is a supermassive black hole at the center of each galaxy. Many studies investigated the relationships between the black hole mass (MBH) and properties of the host galaxy such as the bulge luminosity and mass (see Kormendy & Ho 2013 for a review). The most widely used scaling relation is MBH-σ with the bulge stellar velocity dispersion σ, as found by Ferrarese & Merritt (2000) and Gebhardt et al. (2000). In this thesis a better estimate of MBH is made for the spiral galaxy NGC 3259 than those made by Pagotto et al. (2017). We use images taken with Hubble Space Telescope/Advanced Camera for Surveys/Wide Field Channel with the F814W filter for modelling the surface stellar brightness of the galaxy. By using the images of NGC 3259 of the Sloan Digital Sky Survey in the g’ and r’ bands we measure the bulge g’-r’ color. This color is then converted to the B-V color for calculating the V-band mass-luminosity ratio of the galaxy bulge. Finally, we use a dynamical model of the ionized gas which is assumed to be onto infinitely thin, coplanar, and circular orbits in the potential dictated by the black hole and bulge stars. It produces unresolved gas velocity dispersion predictions that can be directly compared to measurements made by observing the width of the [NII]λ6583 spectral line. We obtain two estimates for the black hole mass 3.4*106 M⨀ and 6.3*105 M⨀ for two different gas disk inclinations of 33° and 81° respectively. These two values are lower than those found by Pagotto et al. (2017) since we considered the stellar contribution to the gravitational potential. The estimates are upper limits on the black hole mass since the gas kinematics is not spatially resolved and non gravitational influences on the gas and its velocity dispersion cannot be a priori ruled out. Both values get closer to the MBH-σ relation of Ferrarese & Ford (2005).
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