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تسجيل مستخدم جديدGalaxy And Mass Assembly (GAMA): The sSFR-M* relation part I - $sigma_{mathrm{sSFR}}$-M* as a function of sample, SFR indicator and environment
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Recently a number of studies have proposed that the dispersion along the star formation rate - stellar mass relation ($sigma_{mathrm{sSFR}}$-M$_{*}$) is indicative of variations in star-formation history (SFH) driven by feedback processes. They found a U-shaped dispersion and attribute the increased scatter at low and high stellar masses to stellar and active galactic nuclei feed-back respectively. However, measuring $sigma_{mathrm{sSFR}}$ and the shape of the $sigma_{mathrm{sSFR}}$-M$_{*}$ relation is problematic and can vary dramatically depending on the sample selected, chosen separation of passive/star-forming systems, and method of deriving star-formation rates ($i.e.$ H$alpha$ emission vs spectral energy distribution fitting). As such, any astrophysical conclusions drawn from measurements of $sigma_{mathrm{sSFR}}$ must consider these dependencies. Here we use the Galaxy And Mass Assembly survey to explore how $sigma_{mathrm{sSFR}}$ varies with SFR indicator for a variety of selections for disc-like `main sequence star-forming galaxies including colour, star-formation rate, visual morphology, bulge-to-total mass ratio, S{e}rsic index and mixture modelling. We find that irrespective of sample selection and/or SFR indicator, the dispersion along the sSFR-M$_{*}$ relation does follow a U-shaped distribution. This suggests that the shape is physical and not an artefact of sample selection or method. We then compare the $sigma_{mathrm{sSFR}}$-M$_{*}$ relation to state-of-the-art hydrodynamical and semi-analytic models and find good agreement with our observed results. Finally, we find that for group satellites this U-shaped distribution is not observed due to additional high scatter populations at intermediate stellar masses.
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