Bibcode
Eliche-Moral, M. C.; Borlaff, A.; Beckman, J. E.; Gutiérrez, L.
Bibliographical reference
Astronomy and Astrophysics, Volume 580, id.A33, 18 pp.
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8
2015
Journal
Citations
11
Refereed citations
9
Description
Context. It has been recently found that the characteristic photometric
parameters of anti-truncated discs in S0 galaxies follow tight scaling
relations. Aims: We investigate whether similar scaling relations
are satisfied by galaxies of other morphological types. Methods:
We have analysed the trends in several photometric planes relating the
characteristic surface brightness and scalelengths of the breaks and the
inner and outer discs of local anti-truncated S0-Scd galaxies, using
published data and fits performed to the surface brightness profiles of
two samples of Type-III galaxies in the R and Spitzer 3.6 μm bands.
We have performed linear fits to the correlations followed by different
galaxy types in each plane, as well as several statistical tests to
determine their significance. Results: We have found that 1) the
anti-truncated discs of all galaxy types from Sa to Scd obey tight
scaling relations both in R and 3.6 μm, as observed in S0s; 2) the
majority of these correlations are significant accounting for the
numbers of the available data samples; 3) the trends are clearly linear
when the characteristic scalelengths are plotted on a logarithmic scale;
and 4) the correlations relating the characteristic surface brightnesses
of the inner and outer discs and the breaks with the various
characteristic scalelengths significantly improve when the scalelengths
are normalized to the optical radius of the galaxy. The observational
uncertainties prevent us from discerning robustly whether the trends
differ between the different types and bands, but we do not find
statistical evidence of significant differences between the
distributions of S0s and spirals or of barred and unbarred galaxies.
These results suggest that the scaling relations of Type-III discs are
independent of the morphological type and the presence (or absence) of
bars within the observational uncertainties of the available datasets.
However, larger and deeper samples are required to confirm this.
Conclusions: The tight structural coupling implied by these scaling
relations imposes strong constraints on the mechanisms proposed to
explain the formation of anti-truncated stellar discs in the galaxies
across the whole Hubble sequence.
Tables 2-7 are available in electronic form at http://www.aanda.org
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Prof.
John E. Beckman