Detalles de publicación
PP 016062
Complex central structures suggest complex evolutionary paths for barred S0 galaxies
Instituto de Astrofisica de Canarias, Via Lactea S/N, E-38205 La Laguna, Spain
Departamento de Astrofisica, Universidad de La Laguna, E-38206 La Laguna, Spain
We investigate three barred lenticular galaxies (NGC~2681, NGC~3945
and NGC~4371) which were previously reported to have complex central
structures but without a detailed structural analysis of these
galaxies' high-resolution data. We have therefore performed four- to
six-component (pseudo-)bulge/disk/bar/ring/point source)
decompositions of the composite ({\it Hubble Space Telescope} plus
ground-based) surface brightness profiles. We find that NGC~2681
hosts three bars, while NGC~3945 and NGC~4371 are double- and
single-barred galaxies, respectively, in agreement with past
isophotal analysis. We find that the bulges in these galaxies are
compact, and have S\'ersic indices of $n\sim 2.2 - 3.6$ and stellar
masses of $M_{*}$ $\sim 0.28\times10^{10} - 1.1\times10^{10} M_{\sun}$.
NGC 3945 and NGC 4371 have intermediate-scale `pseudo-bulges' that are well
described by a S\'ersic model with low $n \la 0.5$ instead of an
exponential ($n=1$) profile as done in the past. We measure emission
line fluxes enclosed within 9 different elliptical apertures,
finding that NGC 2681 has a LINER-type emission inside
$R \sim 3\arcsec$, but the emission line due to star formation is
significant when aperture size is increased. In contrast, NGC 3945
and NGC 4371 have composite (AGN plus star forming)- and LINER-type
emissions inside and outside $R \sim 2\arcsec$, respectively. Our
findings suggest that the three galaxies have experienced a complex
evolutionary path. The bulges appear to be consequences of an
earlier violent merging event while subsequent disk formation via
gas accretion and bar-driven perturbations may account for the
build-up of pseudo-bulges, bars, rings and point sources.
and NGC~4371) which were previously reported to have complex central
structures but without a detailed structural analysis of these
galaxies' high-resolution data. We have therefore performed four- to
six-component (pseudo-)bulge/disk/bar/ring/point source)
decompositions of the composite ({\it Hubble Space Telescope} plus
ground-based) surface brightness profiles. We find that NGC~2681
hosts three bars, while NGC~3945 and NGC~4371 are double- and
single-barred galaxies, respectively, in agreement with past
isophotal analysis. We find that the bulges in these galaxies are
compact, and have S\'ersic indices of $n\sim 2.2 - 3.6$ and stellar
masses of $M_{*}$ $\sim 0.28\times10^{10} - 1.1\times10^{10} M_{\sun}$.
NGC 3945 and NGC 4371 have intermediate-scale `pseudo-bulges' that are well
described by a S\'ersic model with low $n \la 0.5$ instead of an
exponential ($n=1$) profile as done in the past. We measure emission
line fluxes enclosed within 9 different elliptical apertures,
finding that NGC 2681 has a LINER-type emission inside
$R \sim 3\arcsec$, but the emission line due to star formation is
significant when aperture size is increased. In contrast, NGC 3945
and NGC 4371 have composite (AGN plus star forming)- and LINER-type
emissions inside and outside $R \sim 2\arcsec$, respectively. Our
findings suggest that the three galaxies have experienced a complex
evolutionary path. The bulges appear to be consequences of an
earlier violent merging event while subsequent disk formation via
gas accretion and bar-driven perturbations may account for the
build-up of pseudo-bulges, bars, rings and point sources.