List of Abstracts

Clusters of galaxies confront us with two facts that gravity alone cannot explain. Their hot atmospheres hold most of the metals their galaxies ever made, and they carry more entropy than gravitational collapse can supply. Both point to the same source: energy and enriched gas injected by active nuclei as the cluster assembled. I will argue that in powerful radio galaxies at high redshift we are watching that injection happen, and that we can now follow it from the scale of the accretion disk out to the scale of the protocluster.

The evidence on small scales is the genesis of a wind. JWST/MIRI spectroscopy of the Spiderweb galaxy at z = 2.16 resolves a forest of coronal lines spanning a wide range of ionization, and every one of them carries a blueshifted wing. This is a multiphase wind caught at its launching point, chemically enriched in the α elements, and easily powered by the radio source: the mechanical output of the jet exceeds what the wind carries by orders of magnitude, so what limits the flow is not energy but how well it couples to, and loads mass from, the gas around it. Integrated over the lifetime of a radio episode, such a source delivers 10⁶⁰–10⁶¹ erg — the right order to supply the excess entropy of a present-day cluster atmosphere, and delivered together with the metals that atmosphere is observed to carry. The wind's mass and momentum fluxes grow with radius, so it plausibly never escapes the halo at all; far from being a shortcoming, that is what the argument requires, since the heat and the metals must stay where the intracluster baryons will settle.

On larger scales we see the consequences. ALMA and ATCA reveal of order 10¹¹ M⊙ of cold molecular gas spread through the halo in CO and [C I], gas that is already substantially enriched, and the first detection of water in an unlensed distant galaxy falls directly on the radio-jet structures — the signature of the jet working shocks into the circumgalactic medium, as does the warm molecular hydrogen JWST finds at the nucleus, excited by mechanical energy rather than by starlight. That same medium is forming stars in situ across roughly a hundred kiloparsecs, building an extended envelope of the kind that surrounds brightest cluster galaxies today.

The cycle is not one-way. In 4C 41.17 at z = 3.8, ALMA traces a cold stream of comparable mass falling inward along a cosmic filament. Accretion supplies the gas and the gravitational energy, the nucleus returns heat and metals, and the mixture cools, forms stars, and is driven out again. The intracluster medium is the residue of that cycle, and at high redshift we can watch it being made.

How strongly does dark matter interact with itself? Merging galaxy clusters should be the ideal place to find out, but the standard approach has stalled. Dark matter–galaxy offsets turn out to be intrinsically tiny — galaxies stay tightly coupled to the dominant halo potential — and whatever signal survives is entangled with the unknown merger phase, geometry, and initial conditions.

I will present a way around this. Double radio relics trace the pair of shocks launched at pericenter, and the shock-to-shock distance time-stamps precisely where a merger sits in its post-pericenter evolution. The trick is that shock propagation is nearly blind to the self-interaction cross-section, while the halo-to-halo separation is dragged inward by it — so the ratio of the two distances translates directly into σ/m.

Applied to a gold sample of eleven mergers hosting symmetric double relics, this yields σ/m < 0.22 (0.63) cm²/g at 68% (95%) confidence. It is the first cluster-collision constraint to marginalize fully over mass, viewing angle, collision speed, merger phase, impact parameter, and gas profile slope. I will close with what this rules out among SIDM models, and how the method sharpens as upcoming radio surveys expand the relic sample.

Galaxy cluster mergers provide unique laboratories for studying dark matter and cluster assembly. As the most massive gravitationally bound structures in the Universe, their merging can serve as cosmic dark matter colliders, enabling the study of energy scales that are impossible to reproduce on Earth. However, merging clusters are often highly disturbed and complex, and understanding their merger geometry requires observations across multiple tracers and spatial scales. In this talk, we present JWST strong- and weak-lensing analyses of two merging galaxy clusters, the Bullet Cluster and Abell 2744, complemented by multiwavelength observations. In the central region of the Bullet Cluster, the reconstructed dark matter distribution shows close agreement with the intracluster light, suggesting that the ICL can serve as a visual stellar tracer of detailed dark matter morphology even in a highly disturbed merger. In the core of Abell 2744, the geometry of mass bridges connecting the main clumps suggests merger axes that are closely aligned with the observed radio relics. Extending the analysis to larger fields, we examine how these merger signatures connect to the surrounding environment. Around Abell 2744, we find filamentary structures aligned with the inner mass elongation and merger axes. In the Bullet Cluster, wide-field radio observations reveal a radio relic candidate in the outskirts, located along the direction of the mass elongation inferred from the lensing analysis. These results highlight the need to study merging clusters across multiple scales and the synergy between JWST and upcoming wide-field surveys.

The Big Bang has been typically identified as the beginning of the Universe: an event occurring at the “t = 0” moment of time, arrived at by extrapolating back our expanding Universe to a state of arbitrarily high temperatures and densities. Several lines of evidence converge on this picture, namely the major cornerstones of the Big Bang: the expanding Universe, the leftover bath of radiation observable as the cosmic microwave background, the abundance of the light elements forged during an early period of nucleosynthesis, and the growth and evolution of cosmic structure in our Universe. While the extrapolation back to a singularity, naively, is justifiable in an expanding Universe under the rules of General Relativity, those conditions would have led to observable effects that run contrary to what we see. Instead, the Universe is better described by cutting off the matter-and-radiation dominated Universe at some early time, patching on an inflationary epoch where space is expanding exponentially and dominated by some sort of vacuum energy. This is not mere theory more than 40 years on, but is supported by a vast suite of observable evidence. The case for this conclusion, even in the absence of B-mode polarization in the CMB, is laid out here, in the context of the full suite of cosmic evidence that supports, but is not limited by, the Big Bang picture alone.

Hyperluminous infrared galaxies (HyLIRGs) are the rarest and most extreme starbursts and found only in the distant Universe (z ≳ 1). They have intrinsic infrared (IR) luminosities LIR ≥ 10^{13} L⊙ and are commonly found to be major mergers. Recently, the Planck All-Sky Survey to Analyze Gravitationally-lensed Extreme Starbursts project (PASSAGES) searched ~10^4 deg2 of the sky and found ~20 HyLIRGs. We describe a detailed study of PJ0116-24, the brightest (μLIR ≈ 2.6 × 10^{14} L⊙, magnified with μ ≈ 17) Einstein-ring HyLIRG in the southern sky, at z = 2.125, with observations from the near-IR integral-field spectrograph VLT/ERIS and the submillimetre interferometer ALMA. We detected Hα, Hβ, [N ii] and [S ii] lines and obtained an extreme Balmer decrement (Hα/Hβ ≈ 8.73 ± 1.14). We modelled the molecular-gas and ionized-gas kinematics with CO(3–2) and Hα data at ~100–300 pc and (sub)kiloparsec delensed scales, respectively, finding consistent regular rotation. We found PJ0116-24 to be highly rotationally supported (vrot/σ0, mol. gas ≈ 9.4) with a richer gaseous substructure than other known HyLIRGs. Our results imply that PJ0116-24 is an intrinsically massive (Mbaryon ≈ 10^{11.3} M⊙) and rare starbursty disk (star-formation rate, SFR = 1,490 M⊙ yr−1) probably undergoing secular evolution. This indicates that the maximal SFR (≳1,000 M⊙ yr−1) predicted by simulations could occur during a galaxy’s secular evolution, away from major mergers. 

Massive galaxy clusters act as gravitational telescopes, magnifying background supernovae that would otherwise remain undetectable and, in favourable geometries, producing multiple images of the same explosion [1]. The delays between those images give a measurement of the Hubble constant that is independent of both the local distance ladder and the cosmic microwave background, and therefore bears directly on the tension between them [2]. Magnification also opens access to the high-redshift supernova population, whose rates constrain the cosmic star formation history.

I will present our past and ongoing ground-based efforts to find and study these events. Targeted near-infrared campaigns towards galaxy clusters allowed us to measure volumetric core-collapse supernova rates, found to be in agreement with the star formation history, as well as supernova rates for the cluster galaxies themselves [3,4]. Magnification also makes possible spectroscopy that would otherwise be out of reach, which we have used to test whether the intrinsic properties of Type Ia supernovae evolve with redshift, a potential systematic for dark energy measurements [5,6].

I will then turn to the ongoing VST campaign monitoring galaxies and clusters that host gravitationally lensed quasars at roughly daily cadence. This provides both the temporal resolution needed for time delays and the wide field needed to find supernovae in cluster member galaxies, which give an independent distance to the lens [7]. Finally, I will show some of our ongoing efforts within the Euclid-LSST lensed transient search.

Lensed supernova discoveries are expected to increase significantly in the coming years. Well sampled time delays and the identification of cluster-member supernovae both require years of wide-field monitoring that space facilities cannot provide, so ground-based surveys remain essential alongside JWST.

The 10¹²⁰ orders of magnetude discrepancy between the observed cosmological constant and quantum field theory (QFT) predictions remains a central enigma in modern cosmology. This study provides a rigorous analytical derivation of the value 10¹²² by treating gravity as an entropic force arising from information-theoretic constraints. It demonstrated that this result can be derived through aligns precisely with BEKENSTEIN-HAWKING entropy, HAWKING temperature, and Penrose’s information concept. Furthermore the derived dynamic dark energy density A (t), was validated against empirical data from the Max Planck Institute for Radio Astronomy (Planck Mission). Showing exact agreement based on a cosmic age of 13.82 billion years. By linking the „naturalness problem“ to the evolution of cosmic entropy, this study suggests that the accelerated expansion of the universe is an emergent phenomenon bridging the gap between quantum information theory (QIT) and general relativity theory (GRT), driven by the evolution of cosmic entropy. Establishing a direct link between the bit density of the universe and the dynamic nature of dark energy, the study offers a potential resolution to the cosmological constant problem.

The presented article provides a theory of dark energy that appears to have been developed in two complementary ways. On the one hand, this theory is based on physics and mathematics and, on the other hand, it is veryficated on the basis of available data. This correspondends to the discovery of the laws of planetary motion in elliptical planetary orbits by JOHANNES KEPLER in the past. He developed his laws from a large amount of data. Later it was substantiated more thoroughly by ISAAK NEWTON.

The focus is on deriving a formula for the equivalence of energy and time or equivalence of dark energy and the age of the universe. For the first time, this made it possible to calculate the exact value of dark energy. The dark matter of the cosmos is calculated. This derivation of a formula for the equivalence of energy and time provides new theoretical insights and applications in theoretical terms and leads to the discovery of a new law of nature.

The theoretical result is confronted with the numerical value calculated from the available data from the MAX PLANCK Institute for Radio Astronomy. Excellent matching of numerical values of dark energy resulting in four independent paths (by physical-mathematical derivation, derivation on the basis of available data, by STEPHEN HAWKING's contribution, By ROGER PENROSE's contribution with the concept of information) makes the approach plausible.

It is shown that all the information of the universe is encoded on the PLANCK-scale and is „unrolled“ into spacetime by factor t_u (age of the universe) → Holographic Principle.

The fact that the theoretically derived value of the HUBBLE constant (H₀) lies well within the range of astronomical measurements is the strongest indication that the connection between the PLANCK scale and the age of the universe (t_u) is not mere numerology, but a physical principle.

Gravitationally lensed supernovae are rare transients that provide unique opportunities for time-delay cosmography and independent measurements of cosmological parameters. The unparalleled sensitivity of the James Webb Space Telescope (JWST) enables searches for multiply imaged supernovae in galaxy cluster fields, but the expected discovery rate depends strongly on the observing strategy adopted.

We forecast the detection rates of gravitationally lensed supernovae in JWST cluster observations. We simulate JWST observations with different strategies to quantify the detectability of lensed supernovae as a function of redshift, magnification, extinction, and observational parameters. Using these simulations, we optimize the filter selection for lensed supernova searches and combine the resulting detection efficiencies with supernova rate estimates.

Our predictions combine two complementary approaches: one based on known multiply imaged galaxies behind galaxy clusters and their associated supernova rates, and another based on the expected number of lensed supernovae exploding in a given volume behind cluster lenses. By combining these approaches, we aim to provide robust predictions of the number of multiply imaged supernovae that can be discovered with JWST and identify observing strategies that maximize their scientific return. We further explore the expected suitability of detected events for time-delay cosmography to account for the fact that not all lensed supernovae provide equally valuable cosmological constraints.

The advent of the JWST and its phenomenal near-infrared sensitivity and spatial resolution has enabled us over the last few years to uncover a new and rich population of extremely red point-sources at high redshifts dubbed "Little Red Dots" (LRDs). Many properties of LRDs, to their very origin, remain mysterious and they remain one of the most prolific fields of JWST research into the early Universe. Ever since their first discovery, strong gravitational lensing (SL) has represented a sheer treasure trove of information for LRD science through the magnification, which enables us to probe fainter and smaller objects, and time-delays between multiple images, which allow us to measure long-term variability in humane time scales. While many LRDs are known in blank fields, the sample of multiply-imaged LRDs remains limited to one -- A2744-QSO1. With the VENUS JWST cycle 4 program delivering new JWST imaging and spectroscopy of 60 SL fields, the time has come to expand this sample. In VENUS, we have thus-far detected a handful of new multiply-imaged LRDs at z~3-6, and more SL fields are being observed almost every week. In my talk, I will give an overview of what gravitational lensing can do for LRD studies, and present our ongoing efforts to build a statistical sample of lensed LRDs, as well as some preliminary results. With several magnified and multiply-imaged LRDs, we will be able to investigate in unprecedented detail where they fit into our picture of galaxy and black hole formation and the co-evolution of galaxies and black holes.

I will present highlights from our group's studies of the resolved stellar population of five Local Group disk galaxies: Milky Way (MW), Andromeda (M31), Triangulum (M33), Large Magellanic Cloud (LMC), and Small Magellanic Cloud (SMC). These studies include the SPLASH and TREX spectroscopic surveys of several thousand stars in the disk and halo of M31 and M33, respectively, that span a wide range of stellar masses and therefore stellar lifetimes. The SPLASH and TREX surveys of M31 and M33 were carried out with the DEIMOS instrument while the spectroscopic follow up of RR Lyrae stars in the distant MW halo was carried out with the ESI instrument; these two instruments are on the Keck II 10-meter telescope on the summit of Maunakea on the Big Island of Hawaii. The following papers describe the key findings that I will present in my talk: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]

We report a 325 (+24, -4) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar MRK 421 based on Swift-BAT data. This is a confirmation of the QPO reported by Smith et al. (2023), who used RXTE ASM data over a different epoch (1995-2011). The X-ray QPO has been seen for three decades in this object and its detection has also been claimed in other bands. The confirmation of the QPO was done using the EzTao Python toolkit, which builds on the Celerite software, allowing for more complicated modeling of the lightcurve. QPOs can be an important observable for accretion disks, which can be generated by a number of mechanisms, including disk corrugation and warps as well as other mechanisms, and can be modulated both by the orbital frequency and Lense-Thirring precession. In jetted sources such as MRK 421 they can also probe the coupling between the disk and the jet. We revisit various physical origins in both the disk and jet in the light of its extraordinary longevity.

We model spectral energy distributions of 261 X-ray sources to z ~ 5 in the North Ecliptic Pole Time Domain Field, extending prior XMM-Newton and NuSTAR analyses. Using the star-forming main sequence (SFMS) and black hole accretion rate (BHAR) frameworks, we find that SFRs generally lie below the SFMS while most BHARs exceed the population average, as expected for X-ray-selected samples. There is a strong correlation (+0.73) between SFR relative to the SFMS and specific AGN luminosity, $L_{mathrm{AGN}}/M_*$; galaxies with the highest $L_{mathrm{AGN}}/M_*$ exist at or above the SFMS. X-ray luminosity correlates with SFR (+0.80), revealing a star-forming and X-ray luminous ``cold quasar'' population consistent with dramatic, short-timescale accretion episodes. Low-mass galaxies show BHARs well above the population averaged value for their mass whereas high-mass galaxies' SMBHs accrete at the population averaged BHAR, suggesting ``growth spurt'' and ``maintenance-mode'' accretion, respectively. Traditional AGN classifications (obscured, unobscured, or radio-loud) do not reveal these distinctions, demonstrating the X-ray perspective's unique ability to identify rare AGN phases that are critical for the instantaneous link between galaxies and their SMBHs.

I will describe the Roman eXtreme Deep Field (RXDF) program that has been allocated 386.41 hours in Cycle 1-2 of the Roman Space Telescope. The program will do extremely deep imaging in an area close to the North Ecliptic Pole (NEP) to depths comparable to the Hubble Ultra-Deep Field (HUDF) but over an area 60x larger in size, reaching 5-sigma limits of AB = 30 mag in RZYJH, 29 mag in F and 28 mag in K. Thanks to its large, contiguous area (1243 arcmin^2), the RXDF will be the least impacted by the cosmic variance and will be ideal for the clustering analysis of rare objects that need large volumes for statistics (e.g., galaxies/AGNs at z>10).  The RXDF will enable a slew of unprecedented studies on galaxies and accreting SMBHs from the cosmic “dawn” to “noon” to “afternoon”.  The RXDF is also designed to exploit Roman's full potential in time-domain science. The observations will be spitted into three major epochs separated by ~1 year, and each major epoch is further divided into three sub-epochs that are ~10-12 days apart. One major focus of the RXDF time-domain science is supernovae (SNe) at z>2.5. It is expected that the RXDF will result in ~120 SNe Ia (possibly to z ~ 5); ~400 CCSNe total (~10 at z > 6); ~80 SLSNe total (possibly to z~14 and containing Pop-III SNe). The RXDF will also enable a broader range of science topics, including the studies of Galactic brown dwarfs and moving objects in our Solar system.
 

Type Ia supernovae—the thermonuclear explosions of white dwarfs—can be standardized as cosmic distance markers and have played a central role in revealing the accelerated expansion of the Universe. Until recently, however, spectroscopically confirming these events beyond redshift z = 2 was extraordinarily difficult.

We present JWST observations of SN 2022ret, discovered in NIRISS imaging behind the Abell 2744 galaxy cluster and followed with NIRCam imaging and NIRSpec spectroscopy. Emission lines from its host galaxy establish a redshift of z = 2.56, corresponding to light emitted roughly 11 billion years ago. This makes SN 2022ret one of only four spectroscopically confirmed Type Ia supernovae at z>2. Gravitational lensing by Abell 2744 magnified the event by a factor of approximately 1.7.

Although SN 2022ret was discovered after maximum light and its NIRSpec spectrum was obtained more than 60 rest-frame days after peak brightness, independent analyses of its light curves and spectrum consistently classify it as a normal Type Ia supernova. After correcting for lensing and other luminosity-related effects, its peak brightness is consistent with that of typical nearby Type Ia supernovae.

Combining SN 2022ret with two other z > 2 events that satisfy conventional cosmological color criteria, together with a Cepheid-based luminosity calibration, yields H₀ = 71.6 ± 3.3 km s^-1 Mpc^-1, intermediate between early- and late-Universe measurements. The present sample provides no statistically significant evidence for evolving or phantom dark energy. These results demonstrate JWST’s ability to transform supernovae from the Universe’s first few billion years into cosmological probes, while emphasizing the need for larger samples from future JWST, Roman, and Rubin surveys.

The combination of sensitivity and spatial resolution has made JWST a consequential strongly-lensed supernova finder despite limited epochs and coverage. In particular, observations of galaxy clusters have delivered multiple supernovae viable for cosmography, in which the measured ‘time-delay’ between multiple images enables inference of the Hubble Constant. In this talk, I will first give an overview of the current state of supernova time-delay cosmography, including existing measurements and challenges for making this measurements. I will then highlight the success of the recent JWST programs, such as the cycle 4 program VENUS, to yield new cosmography grade supernovae. Given this growing sample, I will provide forecasts and outlook on future cosmographic measurements. Finally, I will highlight how systemtatics relating to strong lensing models can be improved. In particular, I will showcase the power of strongly lensed Type Ia supernovae, such as SN H0pe, which enables measurement of the lensing magnification to break lensing degeneracies.

Time-domain astronomy is entering a new era. With JWST, we can now discover and study supernovae in the early universe, while the Rubin Observatory and the Nancy Grace Roman Space Telescope will find rare transients across wide areas and in unprecedented numbers. These complementary facilities are transforming the transient sky into a laboratory for precision astrophysics and cosmology. In this talk, I will show how these observations are opening new ways to study cosmic expansion and probe the physics of the early universe. High-redshift Type Ia supernovae allow us to test the stability of the standard candles used to trace cosmic acceleration, while strongly lensed supernovae provide an independent route to cosmological distances through time-delay cosmography. I will highlight recent JWST results on both classes of objects and show how they foreshadow the next decade of time-domain astronomy. Together, JWST, Rubin, and Roman will significantly enhance the role of the transient universe as a precision tool for cosmology.

Over 6,000 exoplanets—planets beyond our Solar System—have been identified. These worlds span a remarkable range of sizes, temperatures and atmospheric compositions, including detections of exotic clouds made from glass, molten iron or rubies [1-3]. Because exoplanets are so distant, we cannot usually image them directly. Instead, we infer their atmospheric properties by analysing the tiny fraction of starlight that passes through or is emitted by their atmospheres. Interpreting these spectra allows us to probe atmospheric composition, temperature, and weather, making accurate atmospheric models essential for understanding these distant worlds.

Clouds and hazes play a crucial role in shaping the detectable spectra of planetary atmospheres through absorption and scattering [4]. While many exoplanet models assume these aerosol particles to be spherical, we know from Earth-based measurements that aerosols are likely to form into much more complex fractal aggregate structures. In this talk, I present a recent upgrade that we have made to the widely used cloud code VIRGA (v2.0), enabling characterization of irregular, non-spherical particles while retaining computational efficiency. Our new release incorporates, for the first time, the optics and dynamics of fractal aggregates.

I also present initial results that reveal the measurable influence of particle shape on observed transmission and emission spectra, and I summarize the behaviour of fractal aggregate particles in warm Neptune, hot Jupiter, and brown dwarf atmospheres [5]. I conclude by discussing the important community implications for the interpretation of observational data and the modelling of planetary atmospheres.

The Global Supernova Project is a collaboration between more than 200 scientists worldwide, studying approximately 150 nearby supernovae per year using the Las Cumbres Observatory global network of robotic telescopes combined with more than 20 other facilities, including HST, JWST, SOAR, Gemini, Keck, Rubin, and more.  We work jointly with the Shadow survey using DECam to find SNe in nearby clusters jointly with LSST, and the Public AEON Spectroscopic Survey for Transient Astronomy (PASSTA) using SOAR to get spectra of nearby supernovae.  We have also worked with the Keck Infrared Transient Survey, and PESSTO using the ESO 3.6m.  I will discuss our recent result in Nature —the discovery of Lense-Thirring precession in a superluminous supernova, as well as recent advances in determining the progenitors of SNe Ia.  Finally, I will highlight how public software tools we are creating allow many surveys to work together, trigger observations, and share data more efficiently in the LSST era, including the TOM Toolkit and Hopskotch/HERMES. 

We present James Webb Space Telescope (JWST) and Atacama Large Millimeter Array (ALMA) observations of PJ0846+15, The Koi Pond, a strongly lensed protocluster core at Cosmic Noon. This field offers a magnified view of 11 dusty star-forming galaxies (DSFGs) all at z = 2.67 (within ∆V = 800 km s−1) spanning a projected extent of > 300 kpc lensed by a z = 0.77 foreground cluster. NIRCam and ALMA Band 6 continuum measurements map the stellar distribution and thermal dust emission respectively at a spatial resolution of ∼0.15′′. This multi-wavelength analysis reveals a diverse population of DSFGs with a wide range of morphological features including disks, bulges, spiral arms and bars, evidence for interactions like merger pairs and tidal tails/streams and identification of several clumps/stellar clusters. Comparing the rest-frame J- band continuum (F444W) vs (i-J) color (F277W−F444W), we find a wide range of values, suggesting a >1-dex spread in stellar mass and∆Av > 1 mag. The DSFGs members exhibit varying dust sizes relative to stellar emission - from compact dusty cores to galaxy wide dust emission. Resolved color maps of individual sources showing a spread as high as F277W−F444W= 2 suggesting complex stellar-to-dust geometry. Although gas-rich mergers are identified in the core, the most red and dust emitting members are disks exhibiting clumpy
structure indicating secular growth can drive these starburst events. Such a remarkable range in properties within this sample suggest DSFGs in protocluster core environments follow diverse evolutionary pathways towards their transition into quiescent, elliptical cluster galaxies.

Ultra-Diffuse Galaxies represent some of the faintest galaxies that we can observe, with average surface brightnesses well below the typical sky level. They are also some of the most numerous, with thousands identified in local galaxy clusters [1]. Some are thought to hold remnants of early intense star formation, with billion-year-old stellar populations [2] and large globular cluster populations [3]. However, the evolution of these systems is not well understood, especially the tidal interactions between them and the cluster environment in which they are typically found [4]. In addition to providing insight into galaxy formation physics at small scales, study of these systems can shed light on the nature of dark matter and the connection between dark matter halos and galaxies, given their high dark matter fractions [3]. I will discuss how observations of these systems at higher redshift, possible with observations using JWST, can teach us about their formation and evolution. In particular, recent work has shown that Ultra-Diffuse Galaxies in higher redshift clusters are more similar to field dwarf galaxies (with younger stellar populations and a wider range of sizes) than older systems observed at low-z [5].