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The distribution of moving groups in the solar neighbourhood has been used to constrain dynamical properties of the Milky Way for decades. The kinematic bimodality between the main mode (Hyades, Pleiades, Coma Berenices, and Sirius) and Hercules can be explained by two different bar models – via the outer Lindblad resonance of a bar with a high pattern speed (∼55 km s−1 kpc−1), or via the corotation resonance of a bar with a low pattern speed (∼40 km s−1 kpc−1). Recent works directly studying the kinematics of bar stars and gas flows near the centre of the Galaxy have converged on the low pattern speed model. In this paper, we independently confirm this result by using Gaia DR3 to directly study the variation of Hercules across Galactic azimuth. We find that Hercules increases in V ϕ and becomes stronger as we move towards the minor axis of the bar, and decreases in V ϕ and becomes weaker as we move towards the major axis of the bar. This is in direct agreement with theoretical predictions of a low pattern speed bar model in which Hercules is formed by the corotation resonance with stars orbiting the bar's L4/L5 Lagrange points. [ABSTRACT FROM AUTHOR]

WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, saw first light in late 2022. WEAVE comprises a new 2-deg field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366–959 nm at R ∼ 5000, or two shorter ranges at |$R\sim 20\, 000$|⁠. After summarizing the design and implementation of WEAVE and its data systems, we present the organization, science drivers, and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia 's phase-space information, providing metallicities to its limiting magnitude for ∼3 million stars and detailed abundances for ∼1.5 million brighter field and open-cluster stars; (ii) survey ∼0.4 million Galactic-plane OBA stars, young stellar objects, and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey ∼400 neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionized gas in z < 0.5 cluster galaxies; (vi) survey stellar populations and kinematics in |${\sim} 25\, 000$| field galaxies at 0.3 ≲ z ≲ 0.7; (vii) study the cosmic evolution of accretion and star formation using >1 million spectra of LOFAR-selected radio sources; and (viii) trace structures using intergalactic/circumgalactic gas at z > 2. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator. [ABSTRACT FROM AUTHOR]

Dwarf barred galaxies are the perfect candidates for hosting slowly rotating bars. They are common in dense environments and have a relatively shallow potential well, making them prone to heating by interactions. When an interaction induces bar formation, the bar should rotate slowly. They reside in massive and centrally concentrated dark matter haloes, which slow down the bar rotation through dynamical friction. While predictions suggest that slow bars should be common, measurements of bar pattern speed, using the Tremaine–Weinberg method, show that bars are mostly fast in the local Universe. We present a photometric and kinematic characterization of bars hosted by two dwarf galaxies in the Virgo Cluster, NGC 4483, and NGC 4516. We derive the bar length and strength using the Next Generation Virgo Survey imaging and the circular velocity, bar pattern speed, and rotation rate using spectroscopy from the Multi-Unit Spectroscopic Explorer. Including the previously studied galaxy IC 3167, we compare the bar properties of the three dwarf galaxies with those of their massive counterparts from literature. Bars in the dwarf galaxies are shorter and weaker, and rotate slightly slower with respect to those in massive galaxies. This could be due to a different bar formation mechanism and/or to a large dark matter fraction in the centre of dwarf galaxies. We show that it is possible to push the application of the Tremaine–Weinberg method to the galaxy low-mass regime. [ABSTRACT FROM AUTHOR]

The kinematic plane of stars near the Sun has proven an indispensable tool for untangling the complexities of the structure of our Milky Way (MW). With ever improving data, numerous kinematic 'moving groups' of stars have been better characterized, and new ones continue to be discovered. Here we present an improved method for detecting these groups using MGwave , a new open-source 2D wavelet transformation code that we have developed. Our code implements similar techniques to previous wavelet software; however, we include a more robust significance methodology and also allow for the investigation of underdensities, which can eventually provide further information about the MW's non-axisymmetric features. Applying MGwave to the latest data release from Gaia (DR3), we detect 47 groups of stars with coherent velocities. We reproduce the majority of the previously detected moving groups in addition to identifying three additional significant candidates: one within Arcturus, and two in regions without much substructure at low V R. Finally, we have followed these associations of stars beyond the Solar neighbourhood from Galactocentric radius of 6.5–10 kpc. Most detected groups are extended throughout radius indicating that they are streams of stars possibly due to non-axisymmetric features of the MW. [ABSTRACT FROM AUTHOR]

Stellar bars drive the galaxy secular evolution. While rotating around the galaxy centre with a given angular frequency, the bar pattern speed, they sweep material and modify the galaxy structure. In the LCDM model, bars are expected to slow down by exchanging angular momentum with the other omponents and/or through dynamical friction exerted by the dark matter halo. The only direct method to derive the bar pattern speed, the Tremaine-Weinberg method, revealed that real bars rotate fast, stressing a tension between the observations, conducted to date in the local universe, and the LCDM model. Measuring the bar pattern speed to bars up to z ∼1-2 will reveal if the expected bar evolutionary path is actually taking place and/or to confirm if the dark matter is able to exert friction. Using high resolution N-body simulations we tested the applicability of the Tremaine-Weinberg method to deep spectroscopy of the NIRSpec@JWST for a sample of bars at z ∼1-2. Our analysis can be used to prepare an observational proposal to get dedicated data. [ABSTRACT FROM AUTHOR]

Next-generation wide-field spectroscopic surveys will observe the infall regions around large numbers of galaxy clusters with high sampling rates for the first time. Here, we assess the feasibility of extracting the large-scale cosmic web around clusters using forthcoming observations, given realistic observational constraints. We use a sample of 324 hydrodynamic zoom-in simulations of massive galaxy clusters from TheThreeHundred project to create a mock-observational catalogue spanning 5 R 200 around 160 analogue clusters. These analogues are matched in mass to the 16 clusters targetted by the forthcoming WEAVE Wide-Field Cluster Survey (WWFCS). We consider the effects of the fibre allocation algorithm on our sampling completeness and find that we successfully allocate targets to 81.7 |${\rm {per \,cent}}\, \pm$| 1.3 of the members in the cluster outskirts. We next test the robustness of the filament extraction algorithm by using a metric, D skel, which quantifies the distance to the filament spine. We find that the median positional offset between reference and recovered filament networks is D skel = 0.13 ± 0.02 Mpc, much smaller than the typical filament radius of ∼ 1 Mpc. Cluster connectivity of the recovered network is not substantially affected. Our findings give confidence that the WWFCS will be able to reliably trace cosmic web filaments in the vicinity around massive clusters, forming the basis of environmental studies into the effects of pre-processing on galaxy evolution. [ABSTRACT FROM AUTHOR]

We computed the luminosity of simulated galaxies of the c-eagle project, a suite of 30 high-resolution zoom-in simulations of galaxy clusters based on the eagle simulation. The AB magnitudes are derived for different spectral bands, from ultraviolet to infrared, using the simple stellar population modelling based on the E-MILES stellar spectra library. We take into account obscuration due to dust in star forming regions and diffuse interstellar medium. The g − r colour–stellar mass diagram, at z  = 0.1, presents a defined red sequence, reaching g − r ≃ 0.8, 0.05 dex redder than eagle at high masses, and a well populated blue cloud, when field galaxies are included. The clusters' inner regions are dominated by red-sequence galaxies at all masses, although a non-negligible amount of blue galaxies are still present. We adopt Bayesian inference to compute the clusters LFs, testing for statistical significance of both single and double Schechter functions. The multicolour LFs at z  = 0 show a knee luminosity that peaks in the infrared and increases with the cluster's mass. The faint-end is weakly dependent on colour and mass and shows an upturn in the optical, bounded between −1.25 and −1.39, just moderately steeper than the field. The simulations reproduce, within the observational errors, the spectroscopic LFs of the Hercules and Abell 85 clusters, including their faint end upturn. c-eagle LFs are in broad agreement with observed LFs taken from SDSS and XXL surveys, up to z  = 0.67, showing a rather flat faint end when the observational constrains are taken into account. [ABSTRACT FROM AUTHOR]

We analyse a sample of 12 galaxy clusters, from the Kapteyn IAC WEAVE INT Cluster Survey (KIWICS) looking for dwarf galaxy candidates. By using photometric data in the r and g bands from the Wide Field Camera (WFC) at the 2.5-m Isaac Newton Telescope (INT), we select a sample of bright dwarf galaxies (M |$_r\, \le$| −15.5 mag) in each cluster and analyse their spatial distribution, stellar colour, and as well as their Sérsic index and effective radius. We quantify the dwarf fraction inside the R 200 radius of each cluster, which ranges from ∼0.7 to ∼0.9. Additionally, when comparing the fraction in the inner region with the outermost region of the clusters, we find that the fraction of dwarfs tends to increase going to the outer regions. We also study the clustercentric distance distribution of dwarf and giant galaxies (M |$_r\, \lt $| −19.0 mag), and in half of the clusters of our sample, the dwarfs are distributed in a statistically different way as the giants, with the giant galaxies being closer to the cluster centre. We analyse the stellar colour of the dwarf candidates and quantify the fraction of blue dwarfs inside the R 200 radius, which is found to be less than ∼0.4, but increases with distance from the cluster centre. Regarding the structural parameters, the Sérsic index for the dwarfs we visually classify as early-type dwarfs tends to be higher in the inner region of the cluster. These results indicate the role that the cluster environment plays in shaping the observational properties of low-mass haloes. [ABSTRACT FROM AUTHOR]

For several decades, it has been known that stellar bars in disc galaxies can be triggered by interactions, or by internal processes such as dynamical instabilities. In this work, we explore the differences between these two mechanisms using numerical simulations. We perform two groups of simulations based on isolated galaxies, one group in which a bar develops naturally, and another group in which the bar could not develop in isolation. The rest of the simulations recreate 1:1 coplanar fly-by interactions computed with the impulse approximation. The orbits we use for the interactions represent the fly-bys in groups or clusters of different masses accordingly to the velocity of the encounter. In the analysis, we focus on bars' amplitude, size, pattern speed and their rotation parameter, R = RCR/Rbar. The latter is used to define fast (R < 1.4) and slow rotation (R > 1.4). Compared with equivalent isolated galaxies, we find that bars affected or triggered by interactions: (i) remain in the slow regime for longer, (ii) are more boxy in face-on views and (iii) they host kinematically hotter discs. Within this set of simulations, we do not see strong differences between retrograde or prograde fly-bys. We also show that slow interactions can trigger bar formation. [ABSTRACT FROM AUTHOR]

Context. Numerical studies have shown that the properties of the S0 galaxies with kinematics intermediate between fast and slow rotators are difficult to explain by a scenario of major mergers. Aims. We investigate whether the smoother perturbation induced by minor mergers can reproduce these systems. Methods. We analysed collisionless N-body simulations of intermediate and minor dry mergers onto S0s to determine the structural and kinematic evolution induced by the encounters. The original primary galaxies represent gas-poor fast-rotator S0b and S0c galaxies with high intrinsic ellipticities. The original bulges are intrinsically spherical and have low rotation. Different mass ratios, parent bulges, density ratios, and orbits were studied. Results. Minor mergers induce a lower decrease of the global rotational support (as provided by λe) than encounters of lower mass ratios, which results in S0s with properties intermediate between fast and slow rotators. The resulting remnants are intrinsically more triaxial, less flattened, and span the whole range of apparent ellipticities up to ∈e ∼ 0.8. They do not show lower apparent ellipticities in random projections than initially; on the contrary, the formation of oval distortions and the disc thickening increase the percentage of projections at 0.4 < ∈e < 0.7. In the experiments with S0b progenitor galaxies, minor mergers tend to spin up the bulge and to slightly decrease its intrinsic ellipticity, whereas in the cases of primary S0c galaxies they keep the rotational support of the bulge nearly constant and significantly decrease its intrinsic ellipticity. The remnant bulges remain nearly spherical (B/A ∼ C/A > 0.9), but exhibit a wide range of triaxialities (0.20 < T < 1.00). In the plane of global anisotropy of velocities (δ) vs. intrinsic ellipticity (∈e,intr), some of our models extend the linear trend found in previous major merger simulations towards higher ∈e,intr values, while others clearly depart from it (depending on the progenitor S0). This is consistent with the wide dispersion exhibited by real S0s in this diagram compared with ellipticals, which follow the linear trend drawn by major merger simulations. Conclusions. The smoother changes induced by minor mergers can explain the existence of S0s with intermediate kinematic properties between fast and slow rotators that are difficult to explain with major mergers. The different trends exhibited by ellipticals and S0 galaxies in the δ – ∈e diagram may be pointing to the different role played by major mergers in the build-up of each morphological type. [ABSTRACT FROM AUTHOR]

We have carried out a kinematical and stellar population analysis of the double-barred galaxy NGC357 to provide a more complete characterization of these systems and their role in the formation of galaxy bulges. We clearly identify the presence of the inner bar in the radial velocity and velocity dispersion profiles. The age, metallicity and [Mg/Fe] abundance ratio estimates are very similar to those of ellipticals of equivalent central σ. The [Mg/Fe] value for the bulge of this galaxy suggests formation timescales shorter than 1Gyr. [ABSTRACT FROM PUBLISHER]

Secular evolution theory predicts that spheroidal components are formed thanks to bars that can transport gas to the central regions of the galaxies. This activity would trigger the star formation needed to generate galactic bulges. According to this idea, bars at smaller scales may carry material to the galactic center and feed active galactic nuclei. For the first time, we have carried out a complete kinematical and stellar population analysis of a double-barred galaxy (NGC 357) to determine if this system of two bars is efficient enough to cause that kind of effects. We have measured suitable line-strength indices on high quality spectra to obtain the relative ages and metallicities for the different structural components and thus constrain the star formation history. First results seems to indicate that in the case of NGC 357 the nuclear bar hasn't played an important role in fueling the star formation in the center. [ABSTRACT FROM PUBLISHER]