B/PS bulges in DESI Legacy edge-on galaxies – I. Sample building

Abstract

We present the biggest up-to-date sample of edge-on galaxies with B/PS bulges and X-structures. The sample was prepared using images from the DESI Legacy catalogue and contains about 2000 galaxies. To find suitable candidates in catalogue, we made the assumption that the residues (original images minus model) of galaxies with B/PS bulges should exhibit a characteristic X-shape. Galaxies with such features were selected by eye and then used as input data for a neural network training, which was applied to a bigger sample of edge-on galaxies. Using the available data and the photometric models from the literature, we investigated the observational and statistical properties of the sample created. Comparing the B/D ratios for galaxies with and without B/PS bulges, we found that the B/D ratio for galaxies from our sample is statistically higher, with typical values in the range ≈0.2 − 0.5 depending on the decomposition procedure. We studied how the opening angles ϕ of the X-structure and the length of its rays are distributed in the formed sample and found them to be consistent with previous measurements and predictions from N-body models, e.g. $\varphi \gtrsim 25~\deg$, but measured here for a much larger number of galaxies. We found a sharp increase in the B/PS bulge fraction for stellar masses log M⋆ ≳ 10.4, but for edge-on galaxies, which complements the results of previous works. The sample can be used in future work to test various bar models and their relationship with B/PS bulges, as well as to study their stability and evolution.

The profiles of bars in spiral galaxies

“…As part of our analysis, we classify a subsample of bars in an inclination-and bar-position-angle-limited subsample (B/P-Detection Subsample) into those with and without B/P bulges inside their bars. In line with previous work (Erwin & Debattista 2017;Li et al 2017;Marchuk et al 2022), we find a very strong dependence of B/P presence on galaxy stellar mass (or, equivalently, gas rotation velocity Vrot); this dependence is even stronger than found for the smaller sample of Erwin & Debattista (2017), possibly because we use a more consistent set of stellar mass estimates in this paper.…”

“…Kruk et al (2019) found the same trend using SDSS images for z ∼ 0 barred galaxies, and hints that the trend might be present in higher-redshift galaxies. More recently, Marchuk et al (2022) found a very similar result for B/P bulges identified in edge-on galaxies.…”

“…The studies of Erwin & Debattista (2017), Li et al (2017), Kruk et al (2019), andMarchuk et al (2022) found that such two-component bars are preferentially found in higher-mass galaxies, and thus in early-type spirals and S0s. This means that bars with B/P bulges appear to be found in the same types of galaxies that have flat bar profiles.…”

The luminosity function of ringed galaxies

“…If the galaxies of interest are well restricted in terms of their light distribution or overall shape they can be selected based on their internal parameters, for instance Gini coefficient (G) and M20 index are known to be a good indicator of galaxy's morphology (Lotz, Primack, & Madau 2004) while axial ratio is a good tool to select edge-on galaxies (Mitronova et al 2004;Bizyaev et al 2014). With the ever increasing computational capacity of modern processors it is now possible to employ computer vision techniques with explicit algorithms (Timmis & Shamir 2017) or machine learning methods (Yi et al 2022;Marchuk et al 2022;Makarov et al 2022;Vavilova et al 2021;Cheng et al 2020). Although ML is a very powerful tool that proved itself in a plethora of scenarios this technique has its own limitations, namely, a requirement of a relatively large representative training sample.…”

Testing for relics of past strong buckling events in edge-on galaxies: simulation predictions and data from S4G

“…Attention has been devoted to identifying and cataloguing these systems (e.g. Mitronova et al 2004;Bizyaev et al 2014;Makarov & Antipova 2021;Marchuk et al 2022). High-resolution infrared imaging will soon be available with the James Webb Space Telescope which will help explore current edge-on B/P samples across cosmic time.…”