Description
Organisers: Rita Tojeiro, Alyssa Drake, Meghan Gray, Andrew Pontzen, Tianyi Yang
The cosmic web is the characterisation of the matter distribution in the Universe into distinct environments โ nodes, filaments, sheets, and voids โ that are shaped by the anisotropic nature of gravitational collapse. Each distinct cosmic web environment has been shown to play an important role in the evolution of dark matter halos and galaxies via a variety of complex, multi-scale physical processes. The collective impact of these environments on galaxy and halo transformation is fundamental and diverse: for example, depending on scale, cosmic web environments can sustain galaxy and halo growth, but also inhibit it through stripping or tidal effects.
Our ability to study this impact is driven by rapid advancement of larger, denser, and deeper spectroscopic surveys alongside new generations of cosmological hydrodynamical simulations. We invite talks that consider the evolving anisotropic environment of galaxies and halos from the scales of the circumgalactic medium to that of massive clusters, and that trace the cosmic web via gas, galaxies, dark matter, or galaxy-CMB crosscorrelations. The goal of this session is to bridge research across scales and tracers, in simulations and in observations, such that the UK community can progress on questions such as:
o How do cosmic web environments influence galaxy and halo evolution across scales?
o How can cosmic web environments traced through different methods be compared?
o What links the anisotropic circumgalactic medium to larger-scale cosmic web structures?
o How do galaxies and halos transform as they traverse cosmic web environments?
o How does the cosmic web drive transformations over cosmic time?
The impact of the large-scale cosmic environment on galactic properties remains an open question in galaxy formation. While dark matter halos initially follow linear evolution, their subsequent growth is shaped by complex, non-linear interactions with their surroundings. Observational evidence suggests that proximity to large-scale structures, such as cosmic filaments, can induce quenching in...
The Local Group (LG), as a gravitationally bound system of the Milky Way and Andromeda, as well as their satellites, is a cornerstone of near-field cosmology. However, its utility as a cosmological probe requires understanding how it is related to the cosmic web. Using the ABACUSSUMMIT simulation, we identify LG analogues and quantify their environmental dependence. We find that the coupling...
Understanding the impact of baryonic feedback across different cosmic environments is crucial for accurate interpretation of large-scale structure in Stage-IV cosmological surveys. Hydrodynamical simulations offer a valuable tool for capturing how gas is redistributed by energetic processes, such as AGN feedback, and for predicting how this redistribution alters observable tracers of structure...
The evolution of galaxies is thought to be connected to their cosmic web environment. While environment is typically quantified using observed galaxy catalogues (e.g. using DisPerSE), this approach suffers from survey incompleteness and the uncertain relationship between visible galaxies and the dark matter backbone of the cosmic web.
Here we present the results of arxiv:2503.14732, where...
The evolution of galaxies is dependent on their present-day cosmic environment; whether the galaxies are isolated, or live in dense regions such as galaxy clusters. However, their evolution also depends on the environments they have experienced in the past. Backsplash galaxies are a key example of this -- galaxies that have previously passed through the centre of a galaxy cluster, but now...
Cosmic filamentsโshaped by 13.7 billion years of structure growthโplay a fundamental role in galaxy evolution. At least half of all galaxies reside in filaments, the bridges of matter that channel them into clusters while exposing them to diverse environments. These large-scale structures regulate gas flows, linking galaxies to the intergalactic medium and influence their ability to accrete...
Galaxies do not form in isolation, they grow within the large scale filaments, which affect their formation and evolution. However, the extent to which the cosmic filaments shape galaxies has not been yet understood. Particularly, how the proximity to filaments affects the orientation of a galaxy with respect to the filament and how it can provide important insights into its intrinsic...
We use a sample of 11 $z\approx0.2-0.5$ galaxy clusters from the Cluster Lensing And Supernovae survey with Hubble (CLASH) to analyse the angular dependence of satellite galaxy colour $(B-R)$ and passive galaxy fraction ($f_{\text{pass.}}$) with respect to the major axis of the brightest cluster galaxy (BCG). This phenomenon has been dubbed as \say{anisotropic quenching} describes how...
The relative abundance of the red and blue galaxy populations has been found to vary with stellar mass and environment. We explored the effect of environment considering different types of measurements using a sample of 50,000 galaxies with $0.05 < z < 0.18$. We studied the dependence of the fraction of red galaxies on different measures of the local environment as well as the large-scale...
The impact of the void environment on galaxy evolution is a subject of growing interest, yet many questions remain unanswered. The Calar Alto Void Integral Field Treasury surveY (CAVITY) project aims to address this issue from a novel perspective: using both spectroscopic and spatially resolved data through optical integral field spectroscopy (IFS).
We analyze the CAVITY data cubes with the...
Initial matter density perturbations during the primordial era are set in motion by inflation, dictating the subsequent formation and evolution of large-scale structure. In this research, we explored primordial non-Gaussianity (f_nl) in large-scale structures at z = 1.0 and z = 1.5, focusing on how improvements of the new and upcoming Euclid and SKA instruments will refine f_nl measurements, a...
Context. The 21 cm signal from neutral hydrogen (HI), in cros-correlation mode with photometric surveys, is a crucial probe for cosmology, but contamination from foregrounds and photometric uncertainties affects its measurement. The impact of these contaminants on parameter estimation must be carefully assessed.
Aims. We analyze the auto- and cross-correlation angular power spectra (APS)...
Galaxy evolution is profoundly shaped by environmental processes, yet disentangling internal quenching mechanisms from large-scale influences remains a key challenge. The two-halo galactic conformity effectโthe spatial correlation in galaxy properties extending beyond halo virial radius to ~4 Mpcsโfurther complicates the disentanglement of internal and external quenching processes. Using SDSS...
The number of active galactic nuclei (AGN) in galaxy clusters has been observed to grow by nearly two orders of magnitude from the local universe to $z \sim 1.5$. Star formation rates in clusters have also been observed to rise rapidly over this redshift interval. These trends, along with several other recent observations of high-redshift clusters, have led to the idea that this enhanced star...
Galaxy positions and shapes as tracers of the large-scale structure of the Universe are key observables to test cosmological models in the late Universe down to the non-linear regime. Accurate cosmological constraints require a good understanding of the galaxy-halo connection, i.e. galaxy bias, which can be influenced by complex multi-scale baryonic dynamics and evolve over time. I will...
The matter power spectrum, $P(k)$, is one of the fundamental quantities in the study of large-scale structure in cosmology. In this talk, I will study its small-scale asymptotic limit, and give a theoretical argument to the effect that, for cold dark matter in $d$ spatial dimensions, $P(k)$ has a universal $k^{-d}$ asymptotic scaling with the wave-number $k$, for $k \gg k_{\rm nl}$, where...
Galaxy clusters are the largest gravitationally bound systems in the universe and serve as powerful laboratories for studying cosmology and astrophysical processes. Hydrodynamical simulations provide crucial insights into their formation, evolution, and the complex interplay between dark matter, gas dynamics, and feedback mechanisms. Galaxy clusters are often modeled as spherically symmetric...
Large mock galaxy catalogues are essential to our understanding of rare environments, galaxy clustering, and cosmic variance. However, large simulations are prohibitively expensive to run without making compromises on the resolution and/or complexity of physics. By learning the galaxy-halo connection in zoom simulations, we can map galaxies onto large N-body simulations at low computational...
Galaxy morphology โ the shape, size and internal structure - of a galaxy provides key insights into its properties. These includes any ongoing star formation, their merger history and other internal processes. However, this relationship becomes more complex in the dense environments of massive galaxy clusters. Here, the intracluster medium strips infalling galaxies of their gas with harassment...
The different scales and density environments in the cosmic web contain a wealth of information vital to our understanding of the evolution and content of the Universe. With new spectroscopic surveys mapping the large-scale structure of the Universe in unprecedented detail, we need to develop new theoretical and statistical methods to make use of this cosmological information.
Large...
Filaments account for nearly half of the mass budget of the Universe and play an important role in shaping galaxy properties, such as star formation, metallicities, multi-phase gas properties, as well as the spins and orbits of galaxies. However, in observations we are typically constrained to study filaments traced by galaxies. How are these different from gas and dark matter filaments, and...
Cosmology simulations show that the cosmic web environment of a dark matter halo can have a significant impact on its growth. For example, halos within thick filaments are found to be โstalledโ due to the tidal fields, effectively stopping the halo from gaining mass. Conversely, halos in voids are found to be continuously accreting matter. Whilst the accretion of dark matter onto a halo is not...
The distribution of dark matter (DM) halos is crucial in understanding the large-scale structure of the universe and galaxy evolution and the various factors that affect it. Accreting Super Massive Black Holes, or Active Galactic Nuclei (AGN), may have an important role to play in the galaxy-halo connection. Studying AGN in dense environments, particularly the fraction of satellites and...
Intensity mapping has emerged as one of the most promising techniques to probe the large-scale structure of the Universe across both high and low redshifts, offering new insights into its fundamental properties. The standard model of cosmology is grounded in the cosmological principle, which assumes homogeneity and isotropy on large scales. Homogeneity, in particular, can be tested through the...
Due to high levels of stellar contamination and dust extinction, the sky behind the Magellanic Clouds is not as well-studied as less obscured areas. Therefore, knowledge of background galaxies (and hence galaxy clusters and large-scale structure) in this area has historically been limited, despite the area being covered by a wealth of multiwavelength surveys intended for stellar astrophysics....
The redshift range 3 < z < 6 is an important transitionary period in our Universeโs history, wherein reionization concludes, leaving behind a completely ionized intergalactic medium. Neutral hydrogen (HI) remains only in small islands located towards the centre of halos, where the medium is sufficiently dense to self-shield from ionizing photons.
Consequently, during this time, the HI...
