Galaxy And Mass Assembly (GAMA): The sSFR-M* relation part I – $sigma_{mathrm{sSFR}}$-M* as a function of sample, SFR indicator and environment. (arXiv:1811.03712v1 [astro-ph.GA])

Galaxy And Mass Assembly (GAMA): The sSFR-M* relation part I – $sigma_{mathrm{sSFR}}$-M* as a function of sample, SFR indicator and environment. (arXiv:1811.03712v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Davies_L/0/1/0/all/0/1">L. J. M. Davies</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lagos_C/0/1/0/all/0/1">C. del P. Lagos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Katsianis_A/0/1/0/all/0/1">A. Katsianis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Robotham_A/0/1/0/all/0/1">A. S. G. Robotham</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cortese_L/0/1/0/all/0/1">L. Cortese</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Driver_S/0/1/0/all/0/1">S. P. Driver</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bremer_M/0/1/0/all/0/1">M. N. Bremer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_M/0/1/0/all/0/1">M. J. I. Brown</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brough_S/0/1/0/all/0/1">S. Brough</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cluver_M/0/1/0/all/0/1">M. E. Cluver</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grootes_M/0/1/0/all/0/1">M.W. Grootes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Holwerda_B/0/1/0/all/0/1">B. W. Holwerda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Owers_M/0/1/0/all/0/1">M. Owers</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Phillipps_S/0/1/0/all/0/1">S. Phillipps</a>

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.

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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