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Abstract:

Constraining the mass-sheet degeneracy (MSD) is crucial for improving the precision and accuracy of time-delay cosmography. Joint analyses based on lensing and stellar kinematics have been widely adopted to break the MSD. A three-dimensional (3D) mass and stellar tracer population is required to accurately interpret the kinematics data. Our forward-modeling procedure is aimed at evaluating the projection effects using strong lensing and kinematics observables and to determine an optimal model assumption for the stellar kinematics analysis leading to an unbiased interpretation of the MSD and H_0. We numerically simulated the projection and selection effects for both a triaxial early-type galaxy (ETG) sample from the TNG100 simulation and an axisymmetric sample that matches the properties of slow-rotator galaxies representative of the strong lens galaxy population. Using the axisymmetric sample, we generated mock kinematics observables with spherically aligned axisymmetric Jeans anisotropic modeling (JAM) and assessed the kinematic recovery under different model assumptions. Using the triaxial sample, we quantified the random uncertainty introduced by modeling triaxial galaxies with axisymmetric JAM. We show that spherical JAM analysis of spatially unresolved kinematic data introduces a bias of up to 2%-4% (depending on the intrinsic shape of the lens) in the inferred MSD. Our model largely corrects this bias, resulting in a residual random uncertainty in the range of 0-2.2% in the stellar velocity dispersion (0-4.4% in H_0), depending on the projected ellipticity and the anisotropy of the stellar orbits. This residual uncertainty can be further mitigated by the use of spatially resolved kinematic data, which constrain the intrinsic axis ratio. We also show that the random uncertainty in the kinematics recovery using axisymmetric JAM for axisymmetric galaxies is at the level of 0.24% in the velocity dispersion, and the uncertainty using axisymmetric JAM for triaxial galaxies is at the level of 0.17% in the velocity dispersion.

Abstract:

Abstract Despite the vast amount of energy released by active galactic nuclei (AGN), their role in early galaxy formation and in regulating the growth of supermassive black holes (SMBHs) remains poorly understood. Through new high-resolution zoom-in cosmological simulations, we follow the co-evolution of 105 M⊙ black hole seeds with their host dwarf galaxy. We model ionizing feedback from a Pop III.1 progenitor, applicable to a wide range of internally or externally irradiated SMBH formation scenarios. The simulated suite progressively spans physics ranging from no AGN feedback to more complex setups including thermal, kinetic and radiative feedback – explored for both low and enhanced AGN power. Across all our models, we find that black hole seeds efficiently reach masses of ∼107 M⊙ within a ∼1010 M⊙ halo by z = 8. Although they exhibit notably different mass growth histories, these latter seem unimpeded by the presence of AGN feedback. The simulation including radiative feedback is the most distinct, with super-Eddington episodes driving fast and mass-loaded gas outflows (exceeding 2500 km s−1) up to ∼50 kpc, along with minor stellar mass suppression in the host galaxy. Our measurements are in broad agreement with moderate luminosity quasars recently observed by JWST, producing overmassive black holes (SMBH-to-galaxy mass ratios 0.01 − 1), dynamical masses of ∼109.5 M⊙, stellar masses of ∼108.5 M⊙, and high, though short-lived, Eddington fraction accretion rates. These results advocate for a scenario where AGN feedback allows for rapid SMBH growth during the reionisation era, while driving winds that extend deep into the intergalactic medium – shaping host galaxies as well as more distant surroundings.

Abstract:

<jats:title>Abstract</jats:title> <jats:p>We have carried out a detailed analysis of the 3.4 μm spectral feature arising from Polycyclic Aromatic Hydrocarbons (PAH), using JWST archival data. For the first time in an external galaxy (NGC 6240), we have identified two distinct spectral components of the PAH 3.4 μm feature: a shorter wavelength component at 3.395 μm, which we attribute to short aliphatic chains tightly attached to the aromatic rings of the PAH molecules; and a longer wavelength feature at 3.405 μm that arises from longer, more fragile, aliphatic chains that are weakly attached to the parent PAH molecule. These longer chains are more easily destroyed by far-ultraviolet photons (&amp;gt;5eV) and PAH thermal emission only occurs where PAH molecules are shielded from more energetic photons by dense molecular gas. We see a very strong correlation in the morphology of the PAH 3.395 μm feature with the PAH 3.3 μm emission, the latter arising from robust aromatic PAH molecules. We also see an equally strong correlation between the PAH 3.405 μm morphology and the warm molecular gas, as traced by H2 vibrational lines. We show that the flux ratio PAH 3.395/PAH 3.405 &amp;lt; 0.3 corresponds strongly to regions where the PAH molecules are shielded by dense molecular gas, so that only modestly energetic UV photons penetrate to excite the PAHs. Our work shows that PAH 3.405 μm and PAH 3.395 μm emission features can provide robust diagnostics of the physical conditions of the interstellar medium in external galaxies, and can be used to quantify the energies of the photon field penetrating molecular clouds.</jats:p>

Abstract:

We present a comprehensive analysis of the MIRI Extremely Red Object Virgil, a Lyα emitter at zspec = 6.6379 ± 0.0035 with the photometric properties of a Little Red Dot. Leveraging new JWST/MIRI imaging from the MIDIS and PAHSPECS programs, we confirm Virgil’s extraordinary nature among galaxies in JADES/GOODS-South, exhibiting a strikingly red NIRCam-to-MIRI color (F444W–F1500W = 2.84 ± 0.04 mag). Deep NIRSpec/PRISM spectroscopy from the OASIS program offers key insights into the host galaxy, revealing properties of an average star-forming galaxy during Cosmic Reionization, such as a subsolar metallicity, low-to-moderate dust content, and a relatively high ionization parameter and electron temperature. By estimating the star formation rate of Virgil from UV and Hα, we find evidence that the galaxy is either entering or fading out of a bursty episode. Although line-ratio diagnostics employed at high z would classify Virgil as an active galactic nucleus (AGN), this classification becomes ambiguous once redshift evolution is considered. Nonetheless, Virgil occupies the same parameter space as recently confirmed AGNs at similar redshifts. The new deep MIRI data at 15 μm reinforce the AGN nature of Virgil, as inferred from multiple spectral energy distribution (SED) fitting codes. Virgil’s rising infrared SED and UV excess resemble those of Dust-Obscured Galaxies (DOGs) studied with Spitzer at Cosmic Noon, particularly blue-excess HotDOGs. Our results highlight the need for a multiwavelength approach incorporating MIRI to uncover such extreme sources at z ≳ 6 and to shed light on the interplay between galaxy evolution and early black hole growth during Cosmic Reionization.

Abstract:

James Webb Space Telescope (JWST) has revealed a large population of active galactic nuclei (AGNs) in the distant Universe, which are challenging our understanding of early massive black hole (BH) seeding and growth. We expand the exploration of this population to lower luminosities by stacking 600 NIRSpec grating spectra from the JWST Advanced Deep Extragalactic Survey (JADES) at , in bins of redshift, [O iii]5007 luminosity and equivalent width, UV luminosity, and stellar mass. In multiple stacks, we detect a broad component of H without a counterpart in [O iii], implying that it is not due to outflows but traces the broad-line region of a large population of low-luminosity AGNs not detected in individual spectra. The detection, in some stacks, of high [O iii]4363/H , typical of AGNs, further confirms the detection of a large population of AGNs. We infer that the stacks probe BHs with masses of a few times accreting at rates 0.02–0.1, i.e. a low-mass and dormant parameter space poorly explored by previous studies on individual targets. We identify populations of BHs that fall within the scatter of the local scaling relation, indicating that there is a population of high-z BHs that are not overmassive relative to their host galaxies. Yet, on average, the stacks are still overmassive relative the local relation, with some of them 1–2 dex above it. We infer that the BH mass function at is consistent with models in which BHs evolve through short bursts of super-Eddington accretion.