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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.
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F608
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.
F608
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.
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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.