Conveners
Talks: SN & ISM 1
- Kathryn Kreckel (Heidelberg University)
Talks: CRs & Radation
- Maria Werhahn
Talks: Winds 1
- Jake Bennett (Center for Astrophysics | Harvard & Smithsonian)
Talks: AGN 1
- Meredith Powell
Talks: CGM 1
- Cassandra Lochhaas (Center for Astrophysics | Harvard & Smithsonian)
Talks: SN & ISM 2
- Matt Orr (Flatiron Institute & Rutgers University)
Talks: Winds 2
- Alankar Dutta (Max Planck Institute for Astrophysics)
Talks: CGM 2
- Ramona Augustin (AIP)
Talks: CRs & Magnetic Fields
- Allison Matthews (Carnegie Observatories)
Talks: High-z 1
- Enrico Garaldi (Kavli Institute for Physics and Mathematics of the Universe)
Talks: Low-z 1
- Kirsten Hall (Center for Astrophysics | Harvard & Smithsonian)
Talks: AGN 2
- Rosie Talbot
Talks: High-z 2
- Sirio Belli (Universitร di Bologna)
Talks: Low-z 2
- Matthieu Schaller (Lorentz Institute & Leiden Observatory)
HII regions are fundamental units of the matter cycle in galaxies and their optical emission serves as the main lens through which we study star formation and chemical enrichment across the Universe. They are the sites where ionising radiation and stellar winds have their main impact, turbulence is injected, and heavy elements are dispersed into the interstellar medium. The sizes and internal...
In this talk I will present results from the FIRE cosmological zoom-in simulations exploring the (un)changing properties of the ISM through cosmic time, from redshift three to zero. I will highlight how on (sub)kiloparsec scales, several important properties of the ISM do not change as the galaxies grow and evolve from dispersion-supported, star-bursting objects to rotation-supported, smoothly...
Nearby galaxies observed at high spatial resolution with JWST, ALMA, and MUSE allow us to address fundamental questions related to the influence of young stars on their surrounding interstellar medium (ISM), from cloud to galactic scales: How far can ionizing photons travel, and what physical mechanisms favor their escape from HII regions? How do such processes shape the ISM and influence...
The interstellar and circumgalactic media are the two important reservoirs that fuel star formation in galaxies. Their highly turbulent internal dynamics are shaped by feedback processes such as supernova (SN) explosions and subsequently accelerated cosmic rays (CRs). With recent advances in the hydrodynamical modeling of the interactions between CRs, magnetic fields, and their environment, it...
Modern computational advancements have brought about a resurgence in the consideration of cosmic-rays for driving galactic outflows. This is particularly important in normal galaxies whose thermal and radiation pressure alone is insufficient to expel gas and dust from the disk. Synchrotron radio emission is one of the onlyโand by far the most accessibleโdirect tracers of cosmic-rays in...
Despite the many successes of cosmological galaxy formation and evolution simulations, they commonly implement baryonic feedback in a phenomenological manner by calibrating โboostingโ parameters, which somewhat diminishes their predictive power and restricts their usefulness in interpreting observational data. An alternative approach is to improve the modelling of feedback processes from first...
Thanks to the unprecedented sensitivity of JWST/NIRSpec, we are now able to study neutral atomic outflows in massive galaxies at high redshift. By detecting optical resonant lines such as Na D and Ca K, which have long been inaccessible from the ground, we have characterized the velocity and mass outflow rate of the neutral phase for a representative sample of galaxies at z~2, finding that...
Feedback in the form of outflows is believed to be a key ingredient in galaxy evolution. In cosmic noon galaxies, outflows have mainly been detected - and extensively studied - in the ionised gas phase. However, it has been surmised that a large fraction of outflowing mass may be in molecular gas form, as suggested by results of luminous but rare AGNs and quasars. To gain insights into the...
Massive, large-scale galactic outflows are well known to be important to galaxy evolution. They shape the high-mass end of the mass function, enriching the circumgalactic and intergalactic medium, preventing the cooling catastrophe in galaxy clusters and so on. They also presumably establish the observed correlations between supermassive black holes and their host galaxies, such as the M-sigma...
Relativistic jets emanating from active galactic nuclei (AGNs) play a pivotal role as a feedback mechanism in the Universe, and the cosmic rays (CRs) carried by AGN jets can have profound influence on galaxy properties and the circumgalactic medium. Consequently, self-consistent modeling of CR propagation, spectral evolution, and emission mechanisms is imperative for understanding the thermal...
In this talk, I will show how the study of AGN incidence distributions is a powerful tool to understand the global energetics of AGN feedback. We use the complete, spectroscopic GAMA09 survey (z<0.4) to measure the fraction of galaxies hosting radio and X-ray AGN, defined using LOFAR and eROSITA data, as functions of mass-scaled power indicators. We recover the previously found mass-invariant...
The profound influence of supermassive black holes (SMBHs) on their host galaxies includes altering the orbits of stars, regulating star formation, modifying gas distribution, to name a few. To understand these processes we need to first understand how SMBHs grow through gas accretion and their associated feedback into the surrounding environment. These factors remain a current crucial...
The CGM and IGM contain fuel for future star formation and a record of past feedback. They are uniquely sensitive to the physics of baryonic flows. Diffuse, ionized plasmas such as the CGM are expected to be turbulent, because of the expected high Reynolds number. The presence and magnitude of this turbulence have profound implications for the sources that drive the thermal and dynamic...
Gas flows in and out of galaxies are typically probed by quasar absorption lines which are usually limited to a single sightline through the halo, giving no information on the spatial structure of the gas probed in absorption. First studies using lensed, multiple or extended background objects have shown that there can be significant variation of absorber strengths on relatively small (~kpc...
The gas cycle in and around galaxies is key to their evolution. Cosmological simulations have made enormous progress over the past decade in coming up with effective models for galaxy formation, unifying the Lambda cold dark matter cosmological model with the theory of galaxy formation. Yet, these simulations still struggle to accurately represent warm and cold gas and its cycling in space and...
Massive stars in star-forming regions inject huge amounts of energy and momentum into the ISM, producing ubiquitous superbubbles, turbulent gas motions and outflows. The coupling efficiency of mechanical stellar feedback and its dependence on metallicity remains uncertain in simulations. High angular resolution observations with integral-field spectrographs (e.g., MUSE), combined with the...
Understanding what regulates star formation in galaxies is a fundamental question in astrophysics. However, a simple estimate of the star formation rate (SFR) that a galaxy like ours should have overpredicts the observed SFR by nearly two orders of magnitude. Over the past 50 years, three main explanations have been proposed to account for these low observed SFRs: magnetic fields, turbulence,...
The small-scale processes of star formation and feedback are tightly linked to galaxy evolution through a multi-scale matter cycle. During this cycle, stars form from the interstellar medium (ISM), and reshape it by injecting energy, momentum and metals, completing a feedback loop. The duration and the efficiency of the successive stages of this cycle vary across and within galaxies, but the...
Galactic-scale outflows, driven by supernova feedback in Milky Way-mass galaxies, play a crucial role in transporting metals from the disc to the circumgalactic medium (CGM). The distribution of these metals across different temperature phases within multiphase outflows is key to understanding CGM enrichment, as metal loading varies between phases. High-resolution, idealized simulations of...
Starburst regions in a galaxy are the primary source of stellar-driven winds, which contribute to regulating the star-formation cycle. We investigate the properties of the gas distribution, kinematics, and ionization conditions of the near-side outflow along eight sightlines that reside in the 30 Doradus region of the LMC using UV absorption-line and H I 21-cm radio emission-line observations....
I present the first statistical study of circumgalactic outflows mapped through MUSE observations of Mg II 2796, 2803 emission, revealing extended halos that span several tens of kiloparsecs from their host galaxies. These observations herald a significant advance for deciphering the role of feedback processes in regulating galaxy evolution. Our analysis combines deep MUSE observations with an...
Galaxies interact with their surrounding circumgalactic medium (CGM) through complex feedback mechanisms that regulate their evolution. The CGM, like other astrophysical media, is a turbulent, magnetised environment where mixing processes and radiative cooling drive the formation of multiphase gas. Understanding this multiphase nature is crucial for understanding the baryon cycle, yet...
The circumgalactic medium (CGM) is the nexus of galaxy formation. Fresh gas that fuels star formation must pass through the CGM to reach the interstellar medium, while material accelerated by feedback and expelled from galaxies builds up a gaseous reservoir in the CGM. Observations reveal vast amounts of cold gas in the CGM, yet the processes that shape its dynamics remain uncertain....
Studying the circumgalactic medium (CGM) is a challenge, particularly at the key epoch prior to Cosmic Noon ($z > 2$), where galaxies samples remain very small. However, there is an abundance of Lyman-alpha forest data that contain a wealth of information about the conditions present in this medium.
Morrison et al (2024) showed that a new class of CGM absorption should be studied: Strong...
Cosmic rays (CRs) are ubiquitous in the interstellar medium (ISM) of the Milky Way and nearby galaxies and are thought to play an essential role in governing their evolution. However, many of their properties remain poorly constrained. Since direct measurements of CRs are limited to our local environment, observations of radio and gamma-ray emission arising from CRs provide a powerful tool to...
In previous work, we have shown that magnetic fields are fundamental to the evolution of MW-like galaxies. Specifically, in the Auriga model, magnetohydrodynamic (MHD) simulations produce realistic galaxies with spiral arm structure and radially-extended discs, whilst their hydrodynamic counterparts are systematically smaller, and exhibit bar and stellar ring features not observed in nature....
It is generally believed that the magnetic dynamo in galaxies is a key factor in amplifying small cosmic seed fields to the strengths observed today, both within galaxies and in the CGM/IGM. While simulations with MHD have generally shown modest changes of the overall star formation, magnetic fields are a key factor in the propagation of cosmic rays and their effect on the cloud-scale physics...
Large-scale cosmological simulations of galaxies like IllustrisTNG have been enormously useful at providing quantitative insights on galaxy evolution, especially after the end of Reionization. However, their limited numerical resolution and, crucially, their crude implementations of the physics of star formation, of stellar feedback, of cold gas and of the interstellar medium makes them less...
Directly observing the first quenched galaxies and understanding the feedback mechanisms that shaped their star-formation histories (SFHs), quenching and baryon cycles is crucial for constraining galaxy formation models. Prior to JWST, quenched galaxies were only identified up to z < 4, and high-redshift (z > 3) quenched galaxies were exclusively massive (Mโ > 10^10 Mโ). JWST has now pushed...
Various solutions have been proposed to solve the high-redshift `bright galaxy problem', such as more efficient star formation, more bursty star formation, and top heavy initial mass functions. While equally interesting, each scenario must also differ in how these stellar populations couple to the interstellar medium (ISM) through stellar feedback. In this talk, I will present first results...
There is ample empirical evidence that galaxiesโ star formation efficiency is nearly universal even across a wide range of galactic environments and metallicities. We use a suite of high-resolution hydrodynamics simulations of isolated galaxies at different metallicities to study how the cold, dense interstellar medium and star formation rate vary as a function of chemistry, ionizing radiation...
The cool gaseous halos around galaxies hold some of the keys in understanding feedback and galactic winds. This cool halo gas can be best studied with background quasars, which are very sensitive probes of not only its presence, but also of its kinematics. With a sample of more than 100 galaxy-quasar pairs from the Megaflow survey, I will present the latest constraints on the metal...
Many cosmological simulations typically rely on highly mass loaded, ejective winds, particularly for low mass galaxies, to regulate star formation. Recent hints from observations, analytical theory, and idealised simulations have pointed towards lower mass loadings, and a more preventative form of feedback. Using the Arkenstone winds framework, for the first time we model the impact of low...
The recent advent of high-throughput integral-field-unit spectrographs (IFS) has enabled unprecedented sensitivity in mapping low-density gas, opening new avenues for probing the dynamical states of the interstellar and circumgalactic medium (ISM and CGM). In this talk, I will present an investigation into turbulence and energy injection mechanisms in luminous quasar halos across redshifts...
Feedback from active galactic nuclei (AGN) plays an essential role in current models of galaxy formation, yet the details of this process remain extremely uncertain. I will describe our work combining numerical simulations with microwave and X-ray observations to better constrain this process. Our team has conducted a series of simulations covering a broad range of feedback properties. At...
We present initial results from extremely well-resolved 3D magnetohydrodynamical simulations of idealized galaxy clusters, conducted using the AthenaPK code on the Frontier exascale supercomputer. These simulations explore the self-regulation of galaxy groups and cool-core clusters by cold gas-triggered active galactic nucleus (AGN) feedback incorporating magnetized kinetic jets. Our...
Since JWST began providing breakthrough results in July 2022, our understanding of early galaxy formation has been challenged. While HST enabled us to observe galaxies out to z ~ 10, JWST has pushed this boundary further, revealing an unexpected overabundance of massive galaxies at z > 10. This discovery challenges theoretical models, implying rapid evolution of dark matter halos during this...
Lyman-alpha (Lyฮฑ) emission serves as a valuable probe of gas kinematics in and around galaxies. Observations of high-redshift galaxies frequently exhibit distinctive Lyฮฑ spectral features, often indicative of optically thick, neutral galactic outflows. However, the extent to which galaxy formation simulations can reproduce these observations remains an open question. We investigate this issue...
The COLIBRE model of galaxy formation is the new flagship suite of simulations of the Virgo consortium. It builds upon years of development by a big team and is a substantial leap forward compared to the previous (and existing) generation of models. In brief, the key improvements are: (1) a modelling of the cold ISM phase, (2) a multi-grain, multi-size fully-coupled dust model, (3) the...
Simulations of galaxy formation are mostly unable to resolve the energy-conserving phase of individual supernova events, having to resort to subgrid models to distribute the energy and momentum resulting from stellar feedback. However, the properties of these simulated galaxies, including the morphology, stellar mass formed and the burstiness of the star formation history, are highly sensitive...
Despite recent discoveries of quasar feedback in action through outflows and jets, the amount of energy that the active nucleus is capable of injecting into the extended medium of the host galaxy remains unknown. The most mysterious component of quasar feedback is the lowest density, hot volume-filling gas. Though there are tentative detections of this component via its thermal...
In this talk, I will present the "Beyond" simulation project, a series of hydrodynamical simulations conducted using the AREPO code. I introduce a novel, physically motivated, approach to SMBH feedback, dynamically adjusting feedback efficiency and implementation based on the evolving properties of SMBHs.
The results reveal how this feedback mechanism shapes the properties of galaxies and...
