波茨坦莱布尼茨天体物理学研究所

James Webb Space Telescope (JWST) has revealed the apparent evolution of the black hole (BH)-stellar mass (M-BH-M-*) relation in the early Universe, while remaining consistent with the BH-dynamical mass (M-BH-M-dyn) relation. We predict BH masses for z>3 galaxies in the high-resolution thesan-zoom simulations by assuming that the M-BH-M-dyn relation is fundamental. Even without live BH modelling, our approach reproduces the JWST-observed M-BH distribution, including overmassive BHs relative to the local M-BH-M-* relation. We find that M-BH-M-* declines with M-*, evolving from similar to 0.1 at M-*=10(6) M-circle dot to similar to 0.01 at M-* = 10(10.5) M-circle dot. This trend reflects the dark matter (f(DM)) and gas fractions (f(gas)), which decrease with M-* but show little redshift evolution down to z = 3, resulting in small M-*/M-dyn ratios and thus overmassive BHs in low-mass galaxies. We use prospector-derived stellar masses and star formation rates to infer f(gas) across 48 022 galaxies in the JWST Advanced Deep Extragalactic Survey at 3 < z < 9, finding excellent agreement with our simulation. Our results demonstrate that overmassive BHs would naturally result from a fundamental M-BH-M-dyn relation and be typical of the gas-rich, dark matter-dominated nature of low-mass, high-redshift galaxies. Such overmassive BHs may strongly influence early galaxy formation, and we caution that our approach does not include the self-consistent BH-galaxy co-evolution required for a complete understanding.

Recent James Webb Space Telescope observations hint at unexpectedly intense cosmic star formation in the early Universe, often attributed to enhanced star formation efficiencies (SFEs). Here, we analyse the SFE in THESAN-ZOOM, a novel zoom-in radiation-hydrodynamic simulation campaign of high-redshift (z greater than or similar to 3) galaxies employing a state-of-the-art galaxy formation model resolving the multiphase interstellar medium (ISM). The halo-scale SFE (is an element of(halo)*) the fraction of baryons accreted by a halo that are converted to stars follows a double power-law dependence on halo mass, with a mild redshift evolution above M-halo greater than or similar to 10(95) M-circle star. The power-law slope transitions from similar to 2/3 to similar to 1/3 as halo mass increases, which hints at a transition from energy-driven to momentum-driven outflow. is an element of(halo)* is a factor of 2-3 larger than commonly assumed in empirical galaxy formation models at M-halo less than or similar to 10(95) M-circle star. On galactic (pkpc) scales, the Kennicutt-Schmidt relation of neutral gas is universal in THESAN-ZOOM, following Sigma(SFR) alpha Sigma(2)(gas), indicative of a turbulent energy balance in the ISM maintained by stellar feedback. The rise of is an element of(halo)* with halo mass can be traced primarily to increasing gas surface densities in massive galaxies. These results are is an element of(halo)* primarily increasing gas galaxies. robust against variations in numerical resolution and star formation and feedback models, depending mainly on the total feedback momentum budget. Although the increase in is an element of(halo)* with redshift is modest, it is sufficient to explain the large observed number density of UV-bright galaxies at z >= 12. However, reproducing the brightest sources at M-UV less than or similar to-21 may require extrapolating the SFE beyond the halo mass range covered by THESAN-ZOOM.

The proposed Wide-field Spectroscopic Telescope, a next-generation telescope facility with a 12-meter primary mirror that may be operational in the 2040s, is integrating sustainable considerations from the early design stage. Our preliminary analysis identifies two primary sources of environmental impact that can be mitigated during the design process. First, we are conducting a life-cycle assessment (LCA) to quantify the environmental impact of the 250 spectrographs and the detector cooling systems across the telescope's three instruments, from construction through operation. The carbon footprint estimated through this LCA has been included as a trade-off parameter in the design choices. Second, the WST is expected to produce 1-3 PB/year, requiring careful evaluation of data processing and storage strategies. We explore approaches to monitoring and reducing the carbon footprint associated with data management. Bringing environmental factors into the design process from the start gives us the chance to weigh sustainability alongside scientific performance and cost. By treating the carbon footprint as a core design consideration, we aim to make progress toward more responsible astronomy.

From the luminous quasars at z ∼ 6 to the recent z ∼ 9–11 active galactic nuclei (AGN) revealed by JWST, observations of the earliest black hole (BH) populations can provide unique constraints on BH evolution. We use the BRAHMA simulations with constrained initial conditions to investigate BH assembly in extreme overdense regions. The simulations implement heavy ∼10 ^4 –10 ^5 M _⊙ seeds forming in dense, metal-poor gas exposed to sufficient Lyman–Werner flux. With gas accretion modeled via the Bondi–Hoyle formalism and BH dynamics with a subgrid dynamical friction scheme, we isolate the impact of seeding, dynamics, accretion, and feedback on BH evolution. With fiducial stellar and AGN feedback inherited from IllustrisTNG , accretion is suppressed at z ≳ 9, leaving mergers as the dominant growth channel. Gas accretion dominates at z ≲ 9, where permissive models (super-Eddington or low radiative efficiency) build ∼10 ^9 M _⊙ BHs powering quasars by z ∼ 6, while stricter IllustrisTNG -based prescriptions yield much smaller BHs (∼10 ^6 –10 ^8 M _⊙ ). Our seed models strongly affect mergers at z ≳ 9: only the most lenient models (with ∼10 ^5 M _⊙ seeds) produce enough BH mergers to reach ≳10 ^6 M _⊙ by z ∼ 10, consistent with current estimates for GN-z11. Our dynamical friction model gives low merger efficiencies. Therefore, even in such extreme regions, we are unable to produce ≳10 ^7 M _⊙ BHs by z ∼ 9–10, as currently inferred for GHZ9, UHZ1, and CAPERS-LRD-z9. If the BH-to-stellar mass ratios of these sources are indeed so extreme, they would require either very short BH merger timescales or reduced AGN thermal feedback. Weaker stellar feedback boosts both star formation and BH accretion and cannot raise these ratios.

The X-ray-to-UV relation of active galactic nuclei (AGNs), commonly parametrized via the monochromatic luminosities at 2500 & Aring; and 2 keV, reflects the energetic interplay between the accretion disc and the X-ray-emitting corona, and is key for under-standing accretion physics. Previous studies suggest that disc-dominated emission becomes more prominent with increasing opti-cal luminosity. However, the redshift evolution of this relation remains debated, and a dependence on Eddington ratio, predicted by accretion flow models, is still observationally unconstrained. We revisit this relation using a large nearly all-sky sample by combin-ing the Sloan Digital Sky Survey Quasar Catalog Data Release 16 quasar (QSO) catalogue with X-ray data from XMM-Newton and the SRG/EROSITA All-Sky Survey Data Release 1, yielding 136 745 QSOs at redshifts 0.5 <= z < 3 We introduce a hierarchical Bayesian framework that treats X-ray detections and upper limits uniformly, enabling robust inference from both parametric and non-parametric models. We confirm a tight sublinear log L-x(2 keV)-log L-v (2500 A) correlation, but with a normalization at the lower end of previous estimates. Contrary to most literature results, we detect a mild but systematic redshift evolution: the relation flattens and its intrinsic scatter decreases at higher redshift. This trend is consistent with disc emission increasingly dominated by scattering and enhanced energy transfer to the X-ray corona, potentially indicating redshift evolution in the X-ray bolometric correction. We find no significant dependence on Eddington ratio, in tension with recent accretion flow models.