Description
Organiser: Zoe Le Conte; co organisers: Alex Merrow, Rebecca Smethurst, Thomas Tomlinson
Our understanding of bar formation, evolution, and their interactions with host galaxies is rapidly advancing, revealing new insights into their role in galaxy evolution. Bars are among the most common features in disc galaxies, present in over two-thirds of local spirals, and they influence their hosts by redistributing angular momentum, triggering gas inflows that fuel star formation and potentially feed AGN. Bars also reshape stellar orbits within the galaxy, including the inner regions, outer discs, and stellar halos.
Recent observations from high-resolution surveys like the HST and JWST have provided unprecedented insights into bar-driven evolution across environments and redshifts. Integral field units such as MUSE offer critical data on stellar populations, stellar and gas kinematics, bar-driven star formation and AGN activity, while Gaia enables a star-by-star analysis in the Milky Way.
Simulations complement these advances by modelling barred galaxies with increasing resolution, allowing for detailed studies from high redshifts to the present. These simulations help interpret observational data and improve understanding of stellar chemical evolution and accretion processes, thus facilitating a more accurate interpretation of observational data.
This session will address the still outstanding questions about bar formation, environmental influences on galaxy stability, the kinematics of bars, the role of bars in triggering and fuelling AGN, and bar-driven evolution within dark matter halos. We will discuss how combining high-resolution photometric surveys with cosmological simulations can bridge theory and observations, and how upcoming facilities like MOONS, BlueMUSE, MAVIS, SKA, and ELT will enhance our understanding of galaxy dynamics.
Despite most supermassive black hole (SMBH) growth occurring via merger-free processes, the underlying mechanisms driving this secular evolution are poorly understood. We investigate the role that both strong and weak large-scale galactic bars play in mediating this growth, by analysing the active galactic nucleus (AGN) fraction in strongly barred, weakly barred, and unbarred galaxies up to z...
The age-metallicity relation (AMR) is a key observational tool for understanding the chemical evolution and formation of galactic discs over time. Using the Auriga cosmological simulationsโa suite of high-resolution Milky Way-like galaxy modelsโwe analyze the AMR across the full simulation suite. We have found anomalous AMR features in certain galaxies, which trace past dynamical events such...
Galactic bars rotate at different rates, both in the observed Universe and in simulations, but the precise reasons for these various pattern speeds are not fully understood. We use a high temporal resolution version of the Auriga suite of magneto-hydrodynamical cosmological zoom-in simulations to identify the galaxy properties and histories that set the pattern speeds of bars. In contrast with...
Observations from the SAMI integral field spectroscopic survey have demonstrated that older galaxies have lower spin and younger galaxies have higher spin, even when the effects of stellar mass and environment are controlled. A possible driver of this โspin-ageโ relation is the presence of internal secular heating driven by bars and spiral arms. In the next-generation EAGLE simulation,...
Bars are common structures in spiral galaxies, and until recently, their formation and evolution were primarily studied through numerical simulations of individual galaxies and theoretical models. Over the past decade, however, hydrodynamical cosmological simulations, which model a wide range of physical processes involved in galaxy evolution, have opened new avenues for investigating bar...
Stellar bars in disc galaxies grow as stars in near circular orbits lose angular momentum to their environments, including their Dark Matter (DM) halo, and transform into elongated bar orbits. This angular momentum exchange during galaxy evolution hints at a connection between bar properties, the DM angular momentum, specific angular momentum and halo spin ฮป, the dimensionless form of DM...
Identifying the extent of internal galaxy structures can be incredibly helpful in unravelling their evolutionary histories. For bars in particular this can allow for precise measurements of colour, stellar mass, bar length and alignment with the disk. We present ZooBot:3D, a deep learning model trained using the volunteer classifications from the Galaxy Zoo: 3D project, capable of generating...
Representation learning allows astronomers to uncover relationships between galaxies by using the learned feature space of deep learning models. This space learns the physical appearance of galaxies, with galaxies of a similar appearance occupying a similar region in the feature space. As the appearance of galaxies is strongly affected by their morphology, we can use the feature space to find...
Gas inflows shape galaxy evolution by enhancing star formation (SF), forming nuclear rings/discs, and fuelling AGNs, which trigger outflows and cause quenching. Understanding the mechanisms driving inflows to galactic nuclei is therefore crucial. One well-established mechanism causing gas inflows is bar-driven extended shocks, which manifest as coherent velocity jumps in kinematic maps....
It has been demonstrated in many simulations that secular evolution driven by non-axisymmetric structures is crucial to the evolution of disc galaxies. The Galactic bar, as a dominant non-axisymmetric structure in many disc galaxies, has been studied intensively in simulations. With Gaia DR3, we can now begin to study the imprints that the Galactic bar has left on the Milky Way disc to test...
Galactic bars play a crucial role in the evolution of disk galaxies, influencing gas dynamics, star formation, and secular evolution. However, identifying bars in a large sample of galaxies has been challenging. Our understanding of the impact of bars has leaped forward with Galaxy Zoo 3D: a citizen science project aimed at identifying bars in thousands of galaxies.
In this work, we use a...
Bars have been active and key actors in secular evolution, gas re-distribution and star formation in disc galaxies for at least 10 Gyr. While bars have been extensively studied via observations, models and simulations, we still do not know or even understand how those emerging tumbling structures truly impact the building and evolution of structures.
We have recently provided new strong...
The galactic bar has profound effects on the orbits of stars in the galaxy. A manifestation of the barโs influence is the trapping of stars in resonance with the bar. Stars trapped at resonance can appear as overdensities in phase space, as well as in the space of energy and angular momentum. In the Milky Way, with information on starsโ positions and velocities on a star-by-star basis, we can...
The presence of a stellar bar in a disc galaxy indicates that the galaxy hosts, in its main part, a dynamically settled disc and that bar-driven processes are taking place in shaping its evolution. Therefore, studying the cosmic evolution of the bar fraction in disc galaxies is essential to understanding galaxy evolution. Using the HST, previous studies have found that the bar fraction...
The physical mechanisms responsible for bar formation and destruction in galaxies remain a subject of debate. While we have gained valuable insight into how bars form and evolve from isolated idealized simulations, in the cosmological domain, galactic bars evolve in complex environments with mergers, gas accretion events, in presence of turbulent Inter Stellar Medium (ISM) with multiple star...
The inner regions of Milky Way (MW) are known to contain an enigmatic population of prominent molecular clouds characterised by extremely broad lines. The physical origin of these extended velocity features (EVFs) is debated, although a connection with the โdust lanesโ of the Galactic bar has been hypothesised. In our work, we search for analogous features in the dust lanes of barred galaxies...
Image augmentation is an important aspect of training a deep learning model as it can improve a modelโs performance. However, for a model of a given size, the addition of augmentations may provide no increase in model performance and can cause the training process to take longer, wasting potentially limited time and resources. Because of this we tested the importance of both the image...
NGC 4488 is a small galaxy in the Virgo cluster with an uncertain morphological classification. It is usually classified as a barred galaxy which appears to be in face-on disk, which has short 'fossil' spiral arms while no other part of the disk is detected. It has also been classified as an edge-on disk with a strong warp. Another possible interpretation iwould be that is a merger with 2...
Galaxy rotation curves imply there is unaccounted mass in galaxies, attributed to dark matter. However, constraining the amount of dark matterย in galaxies is challenging due to the disc-halo degeneracy. Stellar bars introduce non-axisymmetries in the potentials of galaxies, which imprint distinctive signatures in the gas morphology, that enable us to break the disc-halo degeneracy. By...
