Context. Stellar bars play an essential role in the secular evolution of disk galaxies because they are responsible for the redistribution of matter and angular momentum. Dynamical models predict that bars become stronger and longer in time, while their rotation speed slows down. Aims. We use the Spitzer Survey of Stellar Structure in Galaxies (S 4 G) 3.6 µm imaging to study the properties (length and strength) and fraction of bars at z = 0 over a wide range of galaxy masses (M * ≈ 10 8 −10 11 M ) and Hubble types (−3 ≤ T ≤ 10). Methods. We calculated gravitational forces from the 3.6 µm images for galaxies with a disk inclination lower than 65• . We used the maximum of the tangential-to-radial force ratio in the bar region (Q b ) as a measure of the bar-induced perturbation strength for a sample of ∼600 barred galaxies. We also used the maximum of the normalized m = 2 Fourier density amplitude (A max 2 ) and the bar isophotal ellipticity (ε) to characterize the bar. Bar sizes were estimated i) visually; ii) from ellipse fitting; iii) from the radii of the strongest torque; and iv) from the radii of the largest m = 2 Fourier amplitude in the bar region. By combining our force calculations with the H  kinematics from the literature, we estimated the ratio of the halo-to-stellar mass (M h /M * ) within the optical disk and by further using the universal rotation curve models, we obtained a first-order model of the rotation curve decomposition of 1128 disk galaxies. Results. We probe possible sources of uncertainty in our Q b measurements: the assumed scale height and its radial variation, the influence of the spiral arms torques, the effect of non-stellar emission in the bar region, and the dilution of the bar forces by the dark matter halo (our models imply that only ∼10% of the disks in our sample are maximal). We find that for early-and intermediate-type disks (−3 ≤ T < 5), the relatively modest influence of the dark matter halo leads to a systematic reduction of the mean Q b by about 10−15%, which is of the same order as the uncertainty associated with estimating the vertical scale height. The halo correction on Q b becomes important for later types, implying a reduction of ∼20−25% for T = 7−10. Whether the halo correction is included or not, the mean Q b shows an increasing trend with T . However, the mean A max 2 decreases for lower mass late-type systems. These opposing trends are most likely related to the reduced force dilution by bulges when moving towards later type galaxies. Nevertheless, when treated separately, both the early-and late-type disk galaxies show a strong positive correlation between Q b and A max 2 . For spirals the mean ε ≈ 0.5 is nearly independent of T , but it drops among S0s (≈0.2). The Q b and ε show a relatively tight dependence, with only a slight difference between early and late disks. For spirals, all our bar strength indicators correlate with the bar length (scaled to isophotal size). Late-type bars are longer than previously found in the literature. The bar fraction...

Boxy/Peanut/X-shaped (B/P/X) bulges are studied using the 3.6 μm images from the Spitzer Survey of Stellar Structure in Galaxies, and the Ks-band images from the Near-IR S0 galaxy Survey. They are compared with the properties of barlenses, defined as lens-like structures embedded in bars, with sizes of ∼50 per cent of bars and axial ratios of ∼0.6–0.9. Based on observations (extending Laurikainen et al.) and recent simulation models, we show evidence that barlenses are the more face-on counterparts of B/P/X-shaped bulges. Using unsharp masks 18 new X-shaped structures are identified, covering a large range of galaxy inclinations. The similar masses and red B−3.6 μm colours of the host galaxies, and the fact that the combined axial ratio distribution of the host galaxy discs is flat, support the interpretation that barlenses and X-shapes are physically the same phenomenon. In Hubble types −3 ≤ T ≤ 2 even half of the bars contain either a barlens or an X-shaped structure. Our detailed 2D multicomponent decompositions for 29 galaxies, fitting the barlens/X-shape with a separate component, indicate very small or non-existent classical bulges. Taking into account that the structures we study have similar host galaxy masses as the Milky Way (MW), our results imply that MW mass galaxies with no significant classical bulges are common in the nearby Universe.

Context. A catalogue of the features for the complete Spitzer Survey of Stellar Structure in Galaxies (S 4 G), including 2352 nearby galaxies, is presented. The measurements are made using 3.6 µm images, largely tracing the old stellar population; at this wavelength the effects of dust are also minimal. The measured features are the sizes, ellipticities, and orientations of bars, rings, ringlenses, and lenses. Measured in a similar manner are also barlenses (lens-like structures embedded in the bars), which are not lenses in the usual sense, being rather the more face-on counterparts of the boxy/peanut structures in the edge-on view. In addition, pitch angles of spiral arm segments are measured for those galaxies where they can be reliably traced. More than one pitch angle may appear for a single galaxy. All measurements are made in a human-supervised manner so that attention is paid to each galaxy. Aims. We create a catalogue of morphological features in the complete S 4 G. Methods. We used isophotal analysis, unsharp masking, and fitting ellipses to measured structures. Results. We find that the sizes of the inner rings and lenses normalized to barlength correlate with the galaxy mass: the normalized sizes increase toward the less massive galaxies; it has been suggested that this is related to the larger dark matter content in the bar region in these systems. Bars in the low mass galaxies are also less concentrated, likely to be connected to the mass cut-off in the appearance of the nuclear rings and lenses. We also show observational evidence that barlenses indeed form part of the bar, and that a large fraction of the inner lenses in the non-barred galaxies could be former barlenses in which the thin outer bar component has dissolved.

Context. Resonance rings and pseudorings (here collectively called rings) are thought to be related to the gathering of material near dynamical resonances caused by non-axisymmetries in galaxy discs. This means that they are the result of secular evolution processes that redistribute material and angular momentum in discs. Studying them may give clues on the formation and growth of bars and other disc non-axisymmetries. Aims. Our aims are to produce a catalogue and an atlas of the rings detected in the Spitzer Survey of Stellar Structure in Galaxies (S 4 G) and to conduct a statistical study of the data in the catalogue. Methods. We traced the contours of rings previously identified and fitted them with ellipses. We found the orientation of bars by studying the galaxy ellipse fits from the S 4 G pipeline 4. We used the galaxy orientation data obtained by the S 4 G pipeline 4 to obtain intrinsic ellipticities and orientations of rings and the bars. Results. ARRAKIS contains data on 724 ringed galaxies in the S 4 G. The frequency of resonance rings in the S 4 G is of 16 ± 1% and 35 ± 1% for outer and inner features, respectively. Outer rings are mostly found in Hubble stages −1 ≤ T ≤ 4. Inner rings are found in a broad distribution that covers the range −1 ≤ T ≤ 7. We confirm that outer rings have two preferred orientations, namely parallel and perpendicular to the bar. We confirm a tendency for inner rings to be oriented parallel to the bar, but we report the existence of a significant fraction (maybe as large as 50%) of inner features that have random orientations with respect to the bar. These misaligned inner rings are mostly found in late-type galaxies (T ≥ 4). We find that the fraction of barred galaxies hosting outer (inner) rings is ∼1.7 times (∼1.3 times) that in unbarred galaxies. Conclusions. We confirm several results from previous surveys as well as predictions from simulations of resonant rings and/or from manifold flux tube theory. We report that a significant fraction of inner rings in late-type galaxies have a random orientation with respect to the bar. This may be caused by spiral modes that are decoupled from the bar and dominate the Fourier amplitude spectrum at the radius of the inner ring. The fact that rings are only mildly favoured by bars suggests that those in unbarred galaxies either formed because of weak departures from the axisymmetry of the galactic potential or that they are born because of bars that were destroyed after the ring formation.Key words. atlases -catalogs -galaxies: statistics -galaxies: structure Tables A.1 and A .2 (catalogue) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via

Context. Spiral galaxies are very common in the local Universe, but their formation, evolution, and interplay with bars remain poorly understood after more than a century of astronomical research on the topic. Aims. We use a sample of 391 nearby galaxies from the S 4 G survey to characterise the winding angle and amplitude of spiral arms as a function of disc properties, such as bar strength, in all kinds of spirals (grand-design, multi-armed, and flocculent). Methods. We derived global pitch angles in 3.6 µm de-projected images from i) average measurements of individual logarithmic spiral segments, and ii) for a subsample of 32 galaxies, from 2-D Fourier analyses. The strength of spirals was quantified from the tangential-to-radial force ratio and from the normalised m = 2 Fourier density amplitudes. Results. In galaxies with more than one measured logarithmic segment, the spiral pitch angle varies on average by ∼ 10 • between segments, but by up to 15 − 20 • . The distribution of the global pitch angle versus Hubble type (T ) is very similar for barred and non-barred galaxies when 1 T 5. Most spiral galaxies (> 90%) are barred for T > 5. The pitch angle is not correlated with bar strength, and only weakly with spiral strength. The amplitude of spirals is correlated with bar strength (and less tightly, with bar length) for all types of spirals. The mean pitch angle is hardly correlated with the mass of the supermassive black hole (estimated from central stellar velocity dispersion), with central stellar mass concentration, or with shear, questioning previous results in the literature using smaller samples. Conclusions. We do not find observational evidence that spiral arms are driven by stellar bars or by invariant manifolds. Most likely, discs that are prone to the development of strong bars are also reactive to the formation of prominent spirals, explaining the observed coupling between bar and spiral amplitudes.