Context. Bars are very common in the centre of the disc galaxies, and they drive the evolution of their structure. The state-of-the-art imaging and redshift surveys of galaxies allow us to study the relationships between the properties of the bars and those of their hosts in statistically significant samples. Aims. A volume-limited sample of 2106 disc galaxies was studied to derive the bar fraction, length, and strength as a function of the morphology, size, local galaxy density, light concentration, and colour of the host galaxy. The sample galaxies were selected to not be strongly disturbed/interacting. Methods. The bar and galaxy properties were obtained by analysing the r-band images of the sample galaxies available in the Sloan Digital Sky Survey Data Release 5. Results. The bars were detected using the ellipse fitting method and Fourier analysis method. They were tested and calibrated with extensive simulations on artificial images. The ellipse fitting method was found to be more efficient in detecting bars in spiral galaxies. The fraction of barred galaxies turned out to be 45%. A bar was found in 29% of the lenticular galaxies, in 55% and 54% of the earlyand late-type spirals, respectively. The bar length (normalised by the galaxy size) of late-type spirals is shorter than in early-type or lenticular ones. A correlation between the bar length and galaxy size was found with longer bars hosted by larger galaxies. The bars of the lenticular galaxies are weaker than those in spirals. Moreover, the unimodal distribution of the bar strength found for all the galaxy types argues against a quick transition between the barred and unbarred statues. There is no difference between the local galaxy density of barred and unbarred galaxies. Besides, neither the length nor strength of the bars are correlated with the local density of the galaxy neighbourhoods. In contrast, a statistical significant difference between the central light concentration and colour of barred and unbarred galaxies was found. Bars are mostly located in less concentrated and bluer galaxies. Conclusions. These results indicate that the properties of bars are strongly related to those of their host galaxies, but do not depend on the local environment.
We use a large sample of upper limits and accurate estimates of supermassive black hole (SMBH) masses coupled with libraries of host galaxy velocity dispersions, rotational velocities and photometric parameters extracted from Sloan Digital Sky Survey i-band images to establish correlations between the SMBH and host galaxy parameters. We test whether the mass of the black hole, M_bh, is fundamentally driven by either local or global galaxy properties. We explore correlations between M_bh and stellar velocity dispersion sigma_e, i-band bulge luminosity L_i,bulge, bulge mass M_bulge, bulge Sérsic index n, bulge mean effective surface brightness
Dynamical models for 17 early-type galaxies in the Coma cluster are presented. The galaxy sample consists of flattened, rotating as well as non-rotating early-types including cD and S0 galaxies with luminosities between M_B = -18.79 and -22.56. Kinematical long-slit observations cover at least the major-axis and minor-axis and extend to 1-4 r_eff. Axisymmetric Schwarzschild models are used to derive stellar mass-to-light ratios and dark halo parameters. In every galaxy, the best fit with dark matter matches the data better than the best fit without. The statistical significance is over 95 per cent for eight galaxies, around 90 per cent for five galaxies and for four galaxies it is not significant. For the highly significant cases, systematic deviations between models without dark matter and the observed kinematics are clearly seen; for the remaining galaxies, differences are more statistical in nature. Best-fitting models contain 10-50 per cent dark matter inside the half-light radius. The central dark matter density is at least one order of magnitude lower than the luminous mass density, independent of the assumed dark matter density profile. The central phase-space density of dark matter is often orders of magnitude lower than that in the luminous component, especially when the halo core radius is large. The orbital system of the stars along the major-axis is slightly dominated by radial motions. Some galaxies show tangential anisotropy along the minor-axis, which is correlated with the minor-axis Gauss-Hermite coefficient H_4. Changing the balance between data-fit and regularization constraints does not change the reconstructed mass structure significantly: model anisotropies tend to strengthen if the weight on regularization is reduced, but the general property of a galaxy to be radially or tangentially anisotropic does not change. This paper is aimed to set the basis for a subsequent detailed analysis of luminous and dark matter scaling relations, orbital dynamics and stellar populations
We present a two-dimensional multi-component photometric decomposition of 404 galaxies from the Calar Alto Legacy Integral Field Area Data Release 3 (CALIFA-DR3). They represent all possible galaxies with no clear signs of interaction and not strongly inclined in the final CALIFA data release. Galaxies are modelled in the g, r, and i Sloan Digital Sky Survey (SDSS) images including, when appropriate, a nuclear point source, bulge, bar, and an exponential or broken disc component. We use a human-supervised approach to determine the optimal number of structures to be included in the fit. The dataset, including the photometric parameters of the CALIFA sample, is released together with statistical errors and a visual analysis of the quality of each fit. The analysis of the photometric components reveals a clear segregation of the structural composition of galaxies with stellar mass. At high masses (log(M ⋆ /M ⊙ ) > 11), the galaxy population is dominated by galaxies modelled with a single Sérsic or a bulge+disc with a bulge-tototal (B/T ) luminosity ratio B/T > 0.2. At intermediate masses (9.5 < log(M ⋆ /M ⊙ ) < 11), galaxies described with bulge+disc but B/T < 0.2 are preponderant, whereas, at the low mass end (log(M ⋆ /M ⊙ ) < 9.5), the prevailing population is constituted by galaxies modelled with either pure discs or nuclear point sources+discs (i.e., no discernible bulge). We obtain that 57% of the volume corrected sample of disc galaxies in the CALIFA sample host a bar. This bar fraction shows a significant drop with increasing galaxy mass in the range 9.5 < log(M ⋆ /M ⊙ ) < 11.5. The analyses of the extended multi-component radial profile result in a volume-corrected distribution of 62%, 28%, and 10% for the so-called Type I (pure exponential), Type II (down-bending), and Type III (up-bending) disc profiles, respectively. These fractions are in discordance with previous findings. We argue that the different methodologies used to detect the breaks are the main cause for these differences.
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