Selim C. Hotinli

Selim C. Hotinli

P. J. E. Peebles Fellow

Cosmic Ecosystems


Over the past three decades, one of the most transformative insights in cosmology has been the realization that the formation and evolution of cosmic structures—supermassive black holes, galaxies, and clusters—are deeply interconnected with the vast cosmic web that underpins the Universe. These processes do not occur in isolation but operate within a dynamic ecosystem where matter and energy flow across scales, driving the growth and transformation of cosmic environments. Understanding this complex system, especially the circumgalactic medium (CGM), is key to revealing how matter is cycled and redistributed through filamentary accretion and outflows from AGN and supernovae. It is also essential for advancing future discoveries in dark matter, the behavior of the cosmic web, the forces shaping cosmic evolution, and related areas.

This conference brought together cosmologists and astrophysicists to explore these interconnected cosmic ecosystems. By examining how structures interact with their environments across scales, the meeting aimed to catalyze new discoveries in astronomy and physics and to provide fresh insights into the forces that govern the Universe. Special attention was given to joint analyses of large-scale structure and weak-lensing data from DESI, Euclid, LSST, and Roman with CMB data from the Simons Observatory and CMB-S4, as well as their integration with observations from JWST, existing and forthcoming X-ray and UV absorption measurements, 21-cm emission, and FRBs.

The conference focused on the complementarity of these data sets and how their alignment can illuminate the multi-phase processes shaping cosmic environments, particularly through joint modeling and simulations across regimes. It also highlighted efforts to bridge the gap between cosmological and astronomical approaches to the CGM—top-down studies of large-scale, hot, virialized gas versus bottom-up investigations of cooler, small-scale phases.

Topics included:

The conference covered a range of themes that focus on delineating and connecting the different scales and phases of the CGM, with a clear emphasis on their links to cosmological themes.

The below themes aimed to build a coherent picture of the cosmic ecosystem by systematically linking scales and phases.

Together, these themese help provide a multi-faceted exploration of how baryonic physics connects all aspects of the universe and form a unified understanding of it across time and space.

These themes are detailed further below.

1. Connecting the Smallest to the Largest: From Subgrid Feedback Physics to Cosmic Large-Scale Structure

Scope: This theme bridges the smallest scales of feedback, such as AGN and supernovae (SNe), with their impact on the large-scale structure (LSS) of the universe. It explores how microphysics (e.g., jets, winds, and turbulence) propagates through simulations and influences the baryonic distribution and clustering on cosmological scales.

Example Topics:

2. Linking Hot Gas to Cold Gas: Baryon Cycling in the Cosmic Ecosystem

Scope: This theme connects the hot ionized gas (e.g., in galaxy clusters and CGM) to cold neutral/molecular gas (e.g., in star-forming regions). It investigates how feedback processes mediate phase transitions, driving the baryon cycle between these reservoirs.

Example Topics:

3. From the Circumgalactic Medium to the Intergalactic Medium: Feedback’s Reach Beyond Galaxies

Scope: This theme examines how feedback-driven processes in the circumgalactic medium (CGM) extend into the intergalactic medium (IGM). It focuses on the transition from galaxy-scale to cosmic web-scale interactions, highlighting turbulence, outflows, and the redistribution of metals and energy.

Example Topics:

4. Tying the Diffuse to the Dense: Connecting Gas Phases and The Role of Turbulence

Scope: This theme focuses on the interplay between diffuse gas (e.g., ionized or neutral IGM) and compact structures (e.g., molecular clouds and galaxies), include discussions on turbulence and cosmic ray interactions. It highlights how energy transfer and phase transitions bridge vastly different density and temperature regimes.

Example Topics:

5. Bridging the Present and the Past: Feedback’s Role in Linking Cosmic History to Current Observables

Scope: This theme connects feedback’s influence on the cosmic ecosystem across time, from early epochs of structure formation to the present universe. It examines how feedback processes evolve with cosmic time and leave imprints observable today, such as in the Lyman-alpha Forest, SZ effect, and FRBs.

Example Topics:

The time has never been more right to unify these fields, as advances in observation, theory and simulations are poised to open new paths to revealing the cosmos’ most profound mysteries.

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Organizing Committee (LOC)

Scientific Organizing Committee (SOC)

Invited Speakers