Star formation in far-IR AGN and non-AGN galaxies in the green valley. II. Morphological analysis. (arXiv:1902.02969v1 [astro-ph.GA])

Star formation in far-IR AGN and non-AGN galaxies in the green valley. II. Morphological analysis. (arXiv:1902.02969v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Mahoro_A/0/1/0/all/0/1">Antoine Mahoro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Povic_M/0/1/0/all/0/1">Mirjana Povi&#x107;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nkundabakura_P/0/1/0/all/0/1">Pheneas Nkundabakura</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nyiransengiyumva_B/0/1/0/all/0/1">Beatrice Nyiransengiyumva</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vaisanen_P/0/1/0/all/0/1">Petri V&#xe4;is&#xe4;nen</a>

This paper studies morphological properties of 103 green valley FIR active
and 2609 non-active galaxies presented in Mahoro et al. 2017. The photometric
data from the COSMOS survey were used, and the morphological parameters, such
as Abraham and Conselice-Bershady concentration indices, Gini, M20 moment of
light, and asymmetry, were analysed taking into account public catalogues.
Furthermore, a visual classification of galaxies was performed. We found that
the fraction of peculiar galaxies with clear signs of interactions and mergers
is significantly higher in AGN (38%) than non-AGN (19%) green valley galaxies,
while non-AGN galaxies from our sample are predominantly spirals (46%). We
found that the largest fraction of our green valley galaxies is located on the
main-sequence (MS) of star formation, independently on morphology, which is in
contrast with most of previous studies carried out in optical. We also found
that FIR AGN green valley galaxies have significantly higher star formation
rates in all analysed morphological types. Therefore, our results suggest that
interactions and mergers obtained in the high fraction of FIR AGN contribute
significantly to high star formation rates observed in the selected sample, but
are not the only mechanism responsible for enhancing star formation, and others
such as AGN positive feedback could contribute as well. In future we will study
in more details the possibility of AGN positive feedback through the
spectroscopic analysis of public and our SALT data.

This paper studies morphological properties of 103 green valley FIR active
and 2609 non-active galaxies presented in Mahoro et al. 2017. The photometric
data from the COSMOS survey were used, and the morphological parameters, such
as Abraham and Conselice-Bershady concentration indices, Gini, M20 moment of
light, and asymmetry, were analysed taking into account public catalogues.
Furthermore, a visual classification of galaxies was performed. We found that
the fraction of peculiar galaxies with clear signs of interactions and mergers
is significantly higher in AGN (38%) than non-AGN (19%) green valley galaxies,
while non-AGN galaxies from our sample are predominantly spirals (46%). We
found that the largest fraction of our green valley galaxies is located on the
main-sequence (MS) of star formation, independently on morphology, which is in
contrast with most of previous studies carried out in optical. We also found
that FIR AGN green valley galaxies have significantly higher star formation
rates in all analysed morphological types. Therefore, our results suggest that
interactions and mergers obtained in the high fraction of FIR AGN contribute
significantly to high star formation rates observed in the selected sample, but
are not the only mechanism responsible for enhancing star formation, and others
such as AGN positive feedback could contribute as well. In future we will study
in more details the possibility of AGN positive feedback through the
spectroscopic analysis of public and our SALT data.

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