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The coming decades will afford the chance to transform our knowledge of the universe and perhaps will reveal compelling evidence of life outside of the Earth. In this presentation I explore the facilities that will enable such advances, advancing the successes of the JWST and 8m ground based telescopes. Uniquely achieved through multi-national collaborations, leveraging the technical and scientific skills of those partners, as well as spreading the costs and risks, a revolutionary scientific future beckons.
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Satellite abundance in Milky Way-like halos plays a crucial role in distinguishing among dark matter models, in particular, in models where a suppression of substructure is expected below a mass scale. One model that has gained recent interest is the Quantum/Wave Dark Matter model, where the dark matter is assumed to be very small (~10-22-10-21eV/c2), this model predicts a sharp suppression of small-scale structures. Capturing the intrinsic quantum field inference has been numerically challenging with current codes. I will show that with the new implemented fluid-wave hybrid scheme in the code GAMER-2 code, we have achieved a self-consistent Wave Dark Matter cosmological simulation of a Milky Way-size halo with a dark Matter particle mass of m=2x10-23eV, which simultaneously resolves the solitonic core of the host halo and captures the complex tidal evolution of subhaloes down to z=0. In this talk, I will discuss the implications of the wave dark matter in dwarf mass halos in isolation and the evolution of Wave DM subhalos inside a MW-mass host. I will mention some consequences on the current and future constraints to the quantum-like hypothesis from observations of the satellite abundance and dynamical mass content of nearby dwarf galaxies.
F608
Cosmic rays interact with astrophysical systems across a vast range of scales, from turbulent galactic environments to the large-scale structure of the Universe. Closely linked to violent, high-energy processes, they act as a dynamic feedback agent, regulating the physical conditions and long-term evolution of galactic and circumgalactic ecosystems. Depending on their energy, cosmic rays can also escape from their host galaxies, propagate through the cosmic web, and produce multi-wavelength and multi-messenger signatures that encode information about their interactions, environments, and transport physics. In this talk, I will highlight key observational tracers—including those from multi-messenger probes—that can be used to map the physical effects of cosmic rays across astrophysical environments and extend studies of galaxies beyond traditional astronomical techniques. I will also examine the role of cosmic rays in shaping baryonic flows around galaxies, and discuss their fate as they traverse the magnetized large-scale structures of the Universe, including the highest-energy particles that never reach Earth.
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Energy feedback from the accretion of gas onto central supermassive black holes of active galaxies is a crucial component of galaxy evolution, which affect the host galaxies and the environment from pc to Mpc scales. Within the standard lambda-CDM cosmology of galaxy formation, negative AGN feedback is a necessary component in numerical simulations to quench star-formation and suppress the formation of massive galaxies. From an observational point of view, there are however controversies over a smoking-gun evidence of star-formation quenching induced by AGN feedback. Evidences are often indirect, in the form of powerful ionized and molecular gas outflows which are frequently observed in galaxies hosting an AGN. At the same time, the exact nature of the impact is observed to vary; from quenching, to enhancement of star-formation in some environments induced by radio jets/lobes. I will describe the performance and analyses of Cosmological Hydrodynamical Simulations, emphasizing on the growth and feedback from SMBHs at galaxy centers; in particular subsequent negative and/or positive feedback. These simulations are executed with a modified version of the SPH code GADGET-3, and includes sub-resolution prescriptions for the physical processes of cooling, star-formation, chemical evolution, SN and AGN feedback. Especially we have sub-resolution models of thermal and kinetic AGN feedback, and switching between the feedback modes depending on the BH accretion rate. In particular, I’ll present some of our work on finding negative and positive AGN feedback in zoom-in cosmological simulations.
F608
Supermassive black hole binaries (SMBHBs) are key to understanding the growth and evolution of supermassive black holes (SMBHs) through mergers. Although direct observation of merging SMBHs via electromagnetic (EM) signals remains challenging, gravitational wave (GW) observatories—such as Pulsar Timing Arrays (PTAs) and space-based interferometers like LISA, TianQin, and Taiji—offer promising windows across different GW frequency bands. Predictions of SMBHB detectability via GWs have largely been based on galaxy merger rates estimated from cosmological simulations or semi-analytical models. However, significant uncertainties remain, such as the formation rates of quasar pairs or discrepancies between galaxy and SMBH merger rates. To address these challenges, our study proposes a novel framework that incorporates observational constraints from the fraction of dual active galactic nuclei (AGNs), which serve as direct tracers of SMBHB formation. Combined with AGN X-ray luminosity functions, this allows us to estimate the population of SMBHBs that emit GWs. Using this framework, we assess the detectability of SMBHBs with a signal-to-noise ratio (SNR) threshold of >5 for each GW observatory. Specifically, we evaluate expected detection rates for PTA enhanced by the Square Kilometre Array (SKA) and space-borne interferometers like LISA. Together, these facilities will establish a multi-frequency GW observational network capable of characterizing SMBHBs across their evolutionary stages.
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The hot corona in X-ray binaries (XRBs) plays a central role in producing hard X-rays through inverse Compton scattering of soft photons. Since the resulting spectrum strongly depends on the coronal geometry and physical properties, understanding the corona is essential for uncovering the mechanisms behind state transitions in XRBs. Although spectral and timing observations have constrained some coronal properties, its geometry and magnetic field structure remain poorly understood. The advent of X-ray polarimetry missions, such as the Imaging X-ray Polarimetry Explorer (IXPE), provides a new opportunity to probe these aspects, as polarization is sensitive to both geometric and magnetic effects. To interpret such observations, we are developing a Monte Carlo simulation framework to model X-ray polarization radiative transfer, incorporating multiple Compton scatterings and magnetic effects. In this seminar, I will present the current results of our ongoing simulations and discuss future prospects for including magnetic field effects in the study.
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Massive black hole binaries emerge in galactic nuclei as a consequence of the dynamics of hierarchical structure formation. Understanding the pairing and binary sinking process until they enter the in-spiral phase governed by gravitational wave emission is thus tightly connected with understanding the physics of galaxy formation and evolution. It is a computationally daunting task involving a huge range of spatial and temporal scales. The rate of GW in-spiral events that the Laser Interferometer Space Antenna (LISA) will detect, as well as the source properties, cannot be predicted without modelling the preceding phases. I will present an overview of the challenges that numerical simulations and semi-analytical models are facing, hinting at a potential "last kiloparsec problem". This is tightly related to modelling various ingredients of galaxy formation physics, from star formation to feedback processes. I will make the case for a new, different approach based on using machine learning to build multi-scale emulators replacing direct numerical simulations. I will then move on to describe how the modelling of the GW in-spiral signal for sources in the LISA band requires accounting for the environmental perturbations induced by surrounding matter. In particular, I will show results from some of the first post-newtonian hydrodynamical simulations that quantify the phase-shift induced on in-spiral waveforms from the residual gas torques from the circumbinary disk in which the two black holes are evolving. These environmental effects open the path for using GWs as unique probes of accretion disk physics at scale not accessible by electromagnetic observations, and, additionally, need to be properly taken into account in future tests of General Relativity using LISA data.
F608
Clarifying origins and acceleration mechanisms of the most energetic particles in the universe has been the centennial endeavor, being one of the most intriguing mysteries in an interdisciplinary research among astroparticle physics, high-energy physics and nuclear physics. Since ultra-high energy cosmic rays (UHECRs) are deflected less strongly by the Galactic and extra-galactic magnetic fields due to their enormous kinetic energies, their arrival directions would be correlated with their origins. A next-generation “astronomy” using UHECRs is hence a potentially viable probe to disentangle mysteries of extremely energetic phenomena in the nearby universe. In this talk, I will give an introduction of cosmic-ray physics, detection techniques, history over 100 years and the latest results of the two giant observatories in operation; Telescope Array experiment and Pierre Auger Observatory including their on-going upgrades. I will also address scientific objectives, requirements and developments for future UHECR observatories.
F608
Dwarf galaxies are the least massive and most abundant galaxies in our universe. Observations in the local universe show they have diverse morphologies; many have spherical or irregular shapes and are not primarily supported by rotation, though some exhibit signs of rotational motion. However, their formation process is still not well understood. Historically, rotational velocities of galactic disks have been used to derive the dynamical masses of galaxies, providing observational constraints on their baryon fractions and dark matter distributions. While this method applies to dwarf galaxies as well, their likely non-rotational nature makes these determinations uncertain. Therefore, understanding the diversity of their kinematics is crucial. I will introduce the fundamental properties and kinematics of the baryonic components in isolated dwarf galaxies with stellar masses below 10^8 solar masses at z=0 in our cosmological zoom-in simulations. I will then focus on their assembly histories and show that late-time (z < 2) galaxy mergers are a trigger in shaping their rotation in the local universe. I will also discuss the relationship between the assembly history and the star formation history and metallicity.
F608
Modern cosmological galaxy formation simulations enable us to study how galaxies evolve together and interact with their surrounding gas. Concurrently, JWST-era galaxy surveys, combined with recent integral-field and multi-object spectrographs, promise unprecedented views into the baryon cycle across spatial scales at Cosmic Noon and beyond. Linking these observational advances to simulations is crucial for informing and validating theoretical models. I will present recent progress addressing this challenge through two complementary approaches. First, I introduce the “cosmosTNG” project, a novel cosmological simulation suite that employs constrained initial conditions matched to the COSMOS field — one of the most extensively studied areas of the sky — enabling direct comparisons with rich observational data sets at Cosmic Noon. Second, I highlight the potential of resonant emission lines, particularly Lyman-alpha, to constrain the properties and distribution of diffuse gas in cosmological simulations. I discuss the opportunities and challenges involved in modeling emission from simulated gas distributions to enable meaningful comparisons with observational signatures.