Bibcode
Costantin, L.; Méndez-Abreu, J.; Corsini, E. M.; Morelli, L.; Aguerri, J. A. L.; Dalla Bontà, E.; Pizzella, A.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 601, id.A84, 20 pp.
Fecha de publicación:
5
2017
Revista
Número de citas
22
Número de citas referidas
22
Descripción
Context. About 20% of low-redshift galaxies are late-type spirals with a
small or no bulge component. Although they are the simplest disk
galaxies in terms of structure and dynamics, the role of the different
physical processes driving their formation and evolution is not yet
fully understood. Aims: We investigated whether small bulges of
late-type spirals follow the same scaling relations traced by
ellipticals and large bulges and if small bulges are disk-like or
classical bulges. Methods: We derived the photometric and
kinematic properties of nine nearby late-type spirals. To this aim, we
analyzed the surface-brightness distribution from the i-band images of
the Sloan Digital Sky Survey and obtained the structural parameters of
the galaxies from a two-dimensional photometric decomposition. We found
a bulge component in seven galaxies of the sample, while the remaining
two resulted in pure disk galaxies. We measured the line-of-sight
stellar velocity distribution within the bulge effective radius from the
long-slit spectra taken with high spectral resolution at the Telescopio
Nazionale Galileo. We used the photometric and kinematic properties of
the sample bulges to study their location in the fundamental plane,
Kormendy, and Faber-Jackson relations defined for ellipticals and large
bulges. Results: We found that our bulges satisfy some of the
photometric and kinematic prescriptions for being considered disk-like
bulges, such as small sizes and masses with nearly exponential light
profiles, small bulge-to-total luminosity ratios, low stellar velocity
dispersions, and ongoing star formation. However, each of these bulges
follows the same scaling relations of ellipticals, massive bulges, and
compact early-type galaxies so they cannot be classified as disk-like
systems. Conclusions: We find a single population of galaxy
spheroids that follow the same scaling relations, where the mass seems
to lead to a smooth transition in the photometric and kinematic
properties from less massive bulges to more massive bulges and
ellipticals.
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