Description
Organisers: Bronwyn Reichardt Chu, Thomas Rintoul; co organisers: Alex Cameron, Fred Jennings, Seoyoung Lyla Jung, Hengxing Pan, Martin Rey, Tianyi Yang
The baryon cycle regulates star formation and shapes galaxies across cosmic time. Gas is accreted onto galaxies from the circumgalactic medium (CGM), used as fuel for star formation, stirred up by young massive stars, and expelled out of galaxies by stellar feedback processes, contributing back to the CGM where it can cool and reaccrete. Characterising multiphase gas - its structure and dynamics, the impact of stellar feedback, and its interplay with local, galaxy and cluster scale environments - is a key problem of modern galaxy formation.
There are many challenges in both observing and simulating the full baryon cycle. Gas is impacted over a vast range of scales, from individual massive star winds, ionising radiation and explosions (~pc) to star formation-driven galaxy-scale outflows contributing to the CGM (~100s kpc) and IGM (~Mpc). In addition, gas within and surrounding galaxies is intrinsically multiphase, spanning more than 8 orders of magnitude in both density and temperature. This requires the combination of multi-wavelength observational data and high-resolution simulations on a range of scales to form an understanding of the role of gas within galaxies.
This session seeks to bridge the gap between observers and simulators to discuss recent progress towards tackling these challenges, solidifying our current understanding of questions such as โHow can we constrain the physics driving the baryon cycle?โ; โWhat effect does environment have on the multiphase baryon cycle?โ; โHow can we connect the effects of feedback across scales?โ; and โHow can we best use numerical simulations to interpret and inform observations of multi-phase gas in and around galaxies (and vice versa)?โ
Stellar and AGN feedback shape star formation and baryon distribution across cosmic time, yet their detailed mechanisms remain uncertain. A major challenge is their multi-scale impact, extending from galaxies to the circumgalactic and intergalactic media (CGM and IGM).
Observations of gas in absorption and emission, combined with hydrodynamical cosmological simulations, provide critical...
Recent advancements in instrumentation have enabled the investigation of star-forming regions in nearby galaxies with unprecedented spatial resolution. To facilitate detailed comparisons between simulations and observations, we generate mock emission line maps based on a state-of-the-art simulation of an ideal H II region, utilizing a novel post-processing pipeline. This simulation couples...
The way galaxies stop forming new stars is a key aspect of galaxy evolution. This is connected with feedback process causing the removal of gas, the fuel of star formation. I will present a novel way to study the interstellar medium (ISM) removal by selecting dusty early-type galaxies detected by Herschel, for which the decrease of gas and dust can be tracked as a function of age. The...
Outflowing gas driven by star formation plays a critical role within the baryon cycle. However the details of this stellar feedback process are still unclear, particularly in starbursting environments. To better constrain the feedback models used to understand galaxy evolution, high resolution IFU observations are needed to spatially resolve star formation-driven outflow properties and link...
Mergers and accretion events are a key element of the baryon cycle, and have strong impacts on the distribution, kinematics and mixing of gas in galaxies. Major mergers are well studied in this regard, but gas-rich minor mergers and cold gas accretion are much less well constrained. A key probe of these external gas accretion events are kinematic misalignments between the stellar and the cold...
The radiative cooling time of hot gas at the centres of many cool cores in clusters of galaxies & massive elliptical galaxies is short, dropping below $10^8$ years. At the same time, the mass cooling rates inferred from simple modelling of X-ray observations of these objects are very low, indicating that either AGN feedback is tightly balanced or that the soft X-rays from cooling gas are...
Ryan Roberts - Constraining the Complex Relationship Between Galaxies and their Dark Matter Haloes Using Explainable AI
Ting-Yun Cheng - Probing the Temperature-Density Relation with Lyman Limit Deuterium Systems
Lilia Magnus - Breaking self-similarity: how dynamical state and feedback affect the redshift evolution of group and cluster gas profiles in the FLAMINGO simulations
Highly mass-loaded outflows from low-mass galaxies are a well-established consequence of ubiquitous implementation of energetic feedback prescriptions into hydrodynamical simulations and are produced by the smallest of galaxies in simulations such as EAGLE and TNG, resulting in mass loadings ($\eta$) between 10 and 100. However the observational literature lacks consensus on the presence of...
The MUSE Ultra-Deep Field (MUDF) is the deepest field observed with MUSE to-date, with over 140h of observations covering a 2โx2โ field centered on a pair of z~3 quasars. This is accompanied by datasets from other instruments including ALMA, HAWK-I, UVES, and XMM-Newton, as well as multi-band HST imaging and the deepest ever WFC3 grism survey. We measure morphologies, stellar masses, and...
Ram Pressure Stripping of satellite galaxies is an important mechanism for enriching the Circumgalactic Medium (CGM). Simulations show that satellites contribute a non-negligible quantity of metals to the CGM, inducing cooling and enhancing accretion onto the central galaxy. Simulations without metal-line cooling in the CGM show systematically lower stellar masses.
While ram pressure...
Most of a galaxy's gas resides in its halo's atmosphere, known as the circumgalactic medium (CGM). Like our own atmosphere, the CGM consists of a hotter, volume-filling component and cooler clouds that can 'rain' onto the galaxy's disc and fuel the formation of new stars. However, simulating the cooler clouds and the entire atmosphere simultaneously poses significant computational challenges,...
Galaxies are surrounded by diffuse ionized gas, which is often called the circumgalactic medium (CGM) and is the least understood part of galactic ecosystems. The CGM harbors more than 80% of the total baryons in a galaxy, is both the reservoir of gas for subsequent star formation and the depository of chemically processed gas, energy, and angular momentum from feedback, however, we do not yet...
The Circumgalactic Medium (CGM) plays a vital role in galaxy evolution, yet its connection to cool gas remains poorly understood. We show that post-starburst galaxies, which recently underwent rapid star formation quenching, exhibit distinct CGM properties. Using ~850,000 quasar sightlines from the SDSS CMASS sample, we measure the stacked MgII equivalent width as a function of impact...
Large-scale structures in the form of galaxy groups and clusters are highly useful cosmological probes, their scaling relations offer a unique way to probe $\Lambda$CDM and assess the evolution of dark matter halos. Deviations from the monolithic collapse scenario (due to both gravitational and astrophysical processes) result in a scatter in the halo property-halo mass scaling relations....
Observational and simulation-based data provide ample evidence for the existence of strong links between the formation and evolution of a galaxy, and the properties of its progenitor dark matter halo. The strongest and most well-documented of these relationships is between the galaxy and $M_{200}$, the total mass of all matter within the virial radius of the dark matter halo. However, when...
Lyman limit systems (LLSs) are high-density clouds in the intergalactic medium, characterised by strong absorption features in quasar spectra due to their substantial neutral hydrogen content. As their density increases, self-shielding becomes significant, reducing photoheating while increasing cooling efficiency through various mechanisms. Meanwhile, they are also affected by additional...
