The Max-Planck-Institut für Astronomie (Max Planck Institute for Astronomy, MPIA) is a research institute of the Max Planck Society (MPG). It is located in Heidelberg, Baden-Württemberg, Germany near the top of the Königstuhl, adjacent to the historic Landessternwarte Heidelberg-Königstuhl astronomical observatory. The institute primarily conducts basic research in the natural sciences in the field of astronomy.In addition to its own astronomical observations and astronomical research, the Institute is also actively involved in the development of observation instruments. The instruments or parts of them are manufactured in the institute's own workshops.
Luminous quasars at the redshift frontier z > 7 serve as stringent probes of super-massive black hole (SMBH) formation and they are thought to undergo much of their growth obscured by dense gas and dust in their host galaxies. Fully characterizing the symbiotic evolution of SMBHs and hosts requires rest-frame optical observations that span spatial scales from the broad-line region (BLR) to the interstellar and circumgalactic medium (ISM and CGM). The James Webb Space Telescope (JWST) now provides the necessary spatially resolved spectroscopy to do so. However, the physical conditions that regulate the interplay between SMBHs and their hosts at the highest redshifts, especially the nature of early feedback phases, remain unclear. We present JWST/NIRSpec integral field unit (IFU) observations of J0313-1806 at z = 7.64, the most distant luminous quasar known. From the rest-frame optical spectrum of the unresolved quasar, we derived a black hole mass of M-BH = (1.63 +/- 0.10)& times;10(9) M-circle dot based on H beta lambda 4861 (H beta) and an Eddington rate of lambda = L/L-Edd = 0.80 +/- 0.05, consistent with previous Mg II lambda 2800-based estimates. J0313-1806 exhibits no detectable [O III] lambda lambda 4959, 5007 emission on nuclear scales (3 sigma upper limit equivalent width of [O III] lambda 5007 < 1.42 & Aring;). Most remarkably, we did detect an ionized gas shell extending out to similar to 1.8 kpc traced by H beta emission that also lacks any significant [O III] lambda lambda 4959, 5007, with a 3 sigma upper limit on the [O III] lambda 5007 to H beta flux ratio of log(10)(F([O III])/F(H beta)) = -1.15. Through photoionization modeling, we demonstrate that the extended emission is consistent with a thin, clumpy outflowing shell where [O III] is collisionally de-excited by dense gas. We interpret this structure as a fossil remnant of a recent blowout phase, providing evidence for episodic feedback cycles in one of the earliest quasars. These findings suggest that dense ISM phases may play a crucial role in shaping the spectral properties of quasars across cosmic time.
Stars are born with a surrounding disk made up of gas entrained by dusty and icy particles, which are the building material for planetary systems. The evolution from small grains towards planetesimals and embryos is regulated by turbulence-driven transport and collisions. Likewise, the migration and growth of planets depends on the gas turbulence. In order to make interpretations of disk observations, one needs to model the turbulent state and the dynamic evolution in these disks. Typical observations of molecular lines provide us with information about the velocity deviation from laminar rotation, and continuum observations of emitted and scattered light helps us determine the spatial and size distribution of dust. The purpose of this review is to provide a guide book on how to set up hydrodynamic and radiation hydrodynamic simulations of a disk around a young star reflecting the current state of code development. These models can then be used to study the effect of turbulence on the distribution and evolution of dust up to planetesimals and planetary embryos, as well as to study the interaction of planets with the disk gas. We will focus on the effects of radiation transport on dynamic stability in global three-dimensional simulations and, therefore, neglect the effects of self-gravity, particle feedback and magnetic fields to some later iteration of the topic.
This chapter provides a brief introduction to the chemical composition of the Sun. The focus of the chapter is on results obtained from the physical analysis of the solar photosphere. Data obtained from meteorites, solar wind and corona measurements, as well as helioseismology, and solar neutrinos are briefly reviewed. The elemental and isotopic composition of the solar system is derived by combining the solar and meteoritic data. The cosmochemical and astronomical abundance scales are described. The results of the determinations of the protosolar chemical composition, as well as the initial and present-day mass fractions of hydrogen, helium, and metals (X, Y, Z) for the solar system are presented in extensive tables. All tables are also available in machine-readable form via Zenodo https://doi.org/10.5281/zenodo.14988840
The population of the little red dots (LRDs) may represent a key phase of supermassive black hole (SMBH) growth. A cocoon of dense excited gas is emerging as a key component to explain the most striking properties of LRDs, such as strong Balmer breaks and Balmer absorption, as well as the weak IR emission. To dissect the structure of LRDs, we analyzed new deep JWST/NIRSpec PRISM and G395H spectra of FRESCO-GN-9771, one of the most luminous known LRDs at z = 5.5. These spectra reveal a strong Balmer break, broad Balmer lines, and very narrow [O III] emission. We revealed a forest of optical [Fe II] lines, which we argue are emerging from a dense (nH = 109 − 10 cm−3) warm layer with electron temperature Te ≈ 7000 K. The broad wings of Hα and Hβ have an exponential profile due to electron scattering in this same layer. The high Hα : Hβ : Hγ flux ratio of ≈10.4 : 1 : 0.14 is an indicator of collisional excitation and resonant scattering dominating the Balmer line emission. A narrow Hγ component, unseen in the other two Balmer lines due to outshining by the broad components, could trace the ISM of a normal host galaxy with a star formation rate of ∼5 M⊙ yr−1. The warm layer is mostly opaque to Balmer transitions, producing a characteristic P Cygni profile in the line centers suggesting outflowing motions. This same layer is responsible for shaping the Balmer break. The broadband spectrum can be reasonably matched by a simple photoionized slab model that dominates the λ > 1500 Å continuum and a low-mass (∼108 M⊙) galaxy that could explain the narrow [O III], with only a subdominant contribution to the UV continuum. Our findings indicate that Balmer lines are not directly tracing the gas kinematics near the SMBH and that the BH mass scale is likely much lower than virial indicators suggest.
Context. Recent observations with the James Webb Space Telescope (JWST) have revealed the presence of young massive clusters (YMCs) as building blocks of the first galaxies during the first billion years of the Universe. They are not only important constituents of the galaxies, but also potential birthplaces of very massive stars (VMSs) and black hole (BH) seeds. Aims. In this paper, we investigate whether runaway stellar collisions in extremely dense clusters inevitably lead to the formation of VMSs and BH seeds. We focus on clusters with initial half-mass densities of rho(h) greater than or similar to 10(8) M-circle dot pc(-3) at very low metallicity (Z = 10(-4)), using idealized initial conditions that assume a fully formed, gas-free, monolithic stellar system. Our goal is to follow their early internal evolution and quantify the efficiency of collisional growth. Methods. We use NBODY6++GPU and MOCCA, including the latest updates of the single stellar evolution (SSE) and binary stellar evolution (BSE), along with specific routines to handle the formation, growth through collisions, and dynamical evolution of VMSs. Results. Our direct N-body and Monte Carlo simulations show that VMSs form rapidly and unavoidably through repeated collisions, reaching final masses of similar to 5 x 10(3) to 4 x 10(4) M-circle dot, before collapsing into BH seeds of similar mass in less than 4 Myr. These results confirm the existence of a critical mass scale at which collisional growth becomes highly efficient, enabling the formation of VMSs and potentially intermediate-mass BHs. Conclusions. We identify a critical mass-density threshold beyond which clusters undergo runaway collisions, leading to efficient BH-seed formation. For YMCs detected with JWST, we expect efficiencies up to similar to 10%, corresponding to BH masses as large as 10(5) M-circle dot. We predict a BH mass-cluster mass scaling relation of log(M-BH / M-circle dot) = -0.76 + 0.76 log(M / M-circle dot). Frequent VMS formation in this regime may also provide a natural explanation for the strong nitrogen enrichment observed in some high-redshift galaxies.
