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In this work, we study the well-posedness of the three dimensional magneto-hydrostatic equation under Grad-Rubin boundary value conditions. The proof relies on a fixed point argument to construct solutions to an elliptic-hyperbolic problem in a perturbative regime by means of pseudo-differential operators with symbols with limited regularity in H\"older spaces. As a byproduct, the employed technique in this work is more flexible and simplifies the arguments of the proof for the previous two-dimensional setting.

The great expansion in offshore power plants is raising the concern regarding the cumulative effect of the electromagnetic field emissions caused by submarine power cables. In this sense, owners are required to predict these emissions during the permitting and consenting process of new power plants. This is a challenging task, especially in the case of HVAC three-core armored cables due to their complex geometry. Customarily, 2D approaches based on the finite element method (FEM) have been employed for evaluating the magnetic field emissions caused by these cables. However, inaccurate results are obtained since the phase conductors and armor twisting is omitted. This work develops, for the first time in the literature, an in-depth analysis of the magnetic field caused by this type of cable through an ultra-shortened 3D-FEM model, which is also faced to experimental measurements taken on an actual 132 kV, 800 mm2 three-core armored cable. Relevant conclusions are derived regarding the impact of the cable design on the magnetic field emissions, including material properties, as well as single and double-layer armors, presenting the proposed model not only as a valuable tool for predicting purposes, but also for optimizing cable design in terms of magnetic field emissions.

Loss allocation of the three different components (conductor, sheaths and armor) of solidly bonded three-core separated lead-sheathed armored cables, frequently employed in offshore wind farms, is challenging due to the lack of accurate enough analytical expressions in the IEC standard. Also, loss allocation through experimental tests leads to inaccurate results since it is based on questionable assumptions. This paper improves both the IEC formulae and experimental methods by means of different analytical corrections in the conductor and sheath loss expressions. To this aim, an ad hoc application interface (Virtual Lab) based on 3D numerical simulations (finite element method) has been developed. This tool virtualizes and automates different test setups to emulate, in few seconds, the most employed experimental procedures in this type of cable. The analytical corrections have been derived from an in-depth analysis of a first set of 368 cables, ranging from 30 to 275 kV. The new loss expressions were successfully applied to a second set of 645 armored cables of quite diverse features (voltages from 10 to 275 kV, sections and dimensional parameters), hence bringing a general framework for any kind of three-core armored cable.

Due to recent advances, the numerical analysis of submarine three-core armored cables can nowadays be developed through the finite element method (FEM) in a small slice of the cable. This strongly reduces the computational burden and simulation time. However, the performance of this ultra-shortened 3D-FEM model is still to be fully assessed with experimental measurements. This paper focuses on this validation for an extensive variety of situations through the experimental measurements available in the specialized literature for up to 10 actual cables. In particular, it deals not only with relevant calculations at power frequency, like the series resistance and inductive reactance or the induced sheath current, but also with other aspects never analyzed before through 3D-FEM simulations, such as the zero sequence impedance, the magnetic field distribution around the power cable, as well as side effects due to the nonlinear properties of the armor wires. All this considering different armoring and sheath bonding configurations. Results show a very good agreement between measured and computed values, presenting the ultra-shortened 3D-FEM model as a suitable tool for the analysis and design of three-core armored cables, and opening the possibility to reduce the need of extensive experimental tests in the design stage of new cables.

Recently, large offshore wind power plants have been installed far from the shore, using long HVAC three-core armored cables to export power. Its high capacitance may contribute to the appearance of unwanted phenomena, such as overvoltages or resonances at low frequencies. To adequately assess these problems, detailed and reliable cable models are required to develop time-domain/frequency-domain analyses on this type of cables. This paper presents, for the first time in the literature, an assessment on the performance of 3D finite element method-based (3D-FEM) models for developing frequency-domain analyses on three-core armored cables, confronting simulation results with experimental measurements found in the literature for three real cables. To this aim, a simplified ultra-shortened 3D-FEM model is proposed to reduce the simulation time during frequency sweeps, through which relevant aspects never analyzed before with frequency-domain 3D-FEM simulations are addressed, such as total losses, induced sheath current, magnetic field around the power cable, positive and zero sequence harmonic impedances, as well as resonant frequencies. Also, a time-domain example derived from the frequency-domain analysis is provided. Remarkable results are obtained when comparing computed values and measurements, presenting the simplified ultra-shortened 3DFEM model as a valuable tool for the frequency-domain analysis of these cables.

This paper analyzes different ways to simulate electromagnetically three-core armored cables in 3D by means of the finite element method. Full periodic models, as lengthy as 36 m, are developed to evaluate the accuracy when simulating only a small portion of the cable, as commonly employed in the literature. The adequate length and boundary conditions for having the same accuracy of full periodic models are also studied. To this aim, five medium voltage and high voltage armored cables are analyzed, obtaining the minimum length of the cable that may be simulated for having accurate results in shorter time and with less computational burden. This also results in the proposal of a new method comprising the advantages of short geometries and the applicability of periodic boundary conditions. Its accuracy is compared with experimental measurements and the IEC standard for 145 kV and 245 kV cables. The results show a very good agreement between simulations and measurements (errors below 4 %), obtaining a reduction in the computation time of about 90 %. This new method brings a more effective tool for saving time and computational resources in cable design and the development of new analytical expressions for improving the IEC standard.

We investigate the main physical mechanisms that shape the intensity and polarization of the Ba II D1 line at 4934 angstroms via radiative transfer numerical experiments. We focus especially on the scattering linear polarization arising from the spectral structure of the anisotropic radiation in the wavelength interval spanned by the line's hyperfine structure (HFS) components in the odd isotopes of barium. After verifying that the presence of the low-energy metastable levels only impacts the amplitude, but not the shape, of the D1 linear polarization, we relied on a two-term atomic model that neglects such metastable levels but includes HFS. The D1 fractional linear polarization shows a very small variation with the choice of atmospheric model, enhancing its suitability for solar magnetic field diagnostics. Tangled magnetic fields with strengths of tens of gauss reduce the linear polarization and saturation is reached at roughly 300 G. Deterministic inclined magnetic fields produce a U/I profile and, if they have a significant longitudinal component, a V/I profile, whose modeling requires accounting for HFS and the Paschen-Back effect. Because of the overlap between HFS components, the magnetograph formula cannot be applied to infer the longitudinal magnetic field. Accurately modeling the D1 intensity and polarization requires an atomic system that includes the metastable levels and the HFS, the detailed spectral structure of the radiation field, the incomplete Paschen-Back regime for magnetic fields, and an accurate treatment of collisions., Comment: Accepted for publication in the Astrophysical Journal

We study little red dots (LRD) detected by JADES and covered by the SMILES MIRI survey. Our sample contains 31 sources, $\sim70$% detected in the two bluest MIRI bands, 40% in redder filters. The median/quartiles redshifts are $z=6.9_{5.9}^{7.7}$ (55% spectroscopic). We analyze the rest-frame ultraviolet through near/mid-infrared spectral energy distributions of LRDs combining NIRCam and MIRI observations, using a variety of modeling techniques that include emission from stars, dust, and (un)obscured active galactic nuclei (AGN). The NIRCam$-$MIRI colors, for $\geq10$ $\mu$m, are bluer than direct pure emission from AGN tori; the spectral slope flattens in the rest-frame near-infrared, consistent with a 1.6 $\mu$m stellar bump. Both observations imply that stellar emission makes the dominant contribution at these wavelengths, expediting a stellar mass estimation: the median/quartiles are $\log \mathrm{M_\star/M_\odot}=9.4_{9.1}^{9.7}$. The number density of LRDs is $10^{-4.0\pm0.1}$ Mpc$^{-3}$, accounting for $14\pm3$% of the global population of galaxies with similar redshifts and masses. The flat ultraviolet spectral range is dominated by young stars. The rest-frame near/mid-infrared (2-4 $\mu$m) spectral slope reveals significant amounts of dust (bolometric stellar attenuation $\sim3-4$ mag) heated by strong radiation fields arising from highly embedded compact sources. Our models imply $<0.4$ kpc heating knots, containing dust-enshrouded OB stars or an AGN producing a similar radiation field, obscured by $\mathrm{A(V)}>10$ mag. We conclude that LRDs are extremely intense and compact starburst galaxies with mass-weighted ages 5-10 Myr, very efficient in producing dust, their global energy output dominated by the direct and dust-recycled emission from OB stars, with some contribution from obscured AGN in the mid-infrared., Comment: Accepted for publication in ApJ, LRD average models provided in https://tinyurl.com/lrdmodels

We have determined the proper motions (PMs) of 12 dwarf galaxies in the Local Group (LG), ranging from the outer Milky Way (MW) halo to the edge of the LG. We used HST as the first and Gaia as the second epoch using the GaiaHub software. For Leo A and Sag DIG we also used multi-epoch HST measurements relative to background galaxies. Orbital histories derived using these PMs show that two-thirds of the galaxies in our sample are on first infall with $>$90\% certainty. The observed star formation histories (SFHs) of these first-infall dwarfs are generally consistent with infalling dwarfs in simulations. The remaining four galaxies have crossed the virial radius of either the MW or M31. When we compare their star formation (SF) and orbital histories we find tentative agreement between the inferred pattern of SF with the timing of dynamical events in the orbital histories. For Leo~I, SF activity rises as the dwarf crosses the MW's virial radius, culminating in a burst of SF shortly before pericenter ($\approx1.7$~Gyr ago). The SF then declines after pericenter, but with some smaller bursts before its recent quenching ($\approx0.3$~Gyr ago). This shows that even small dwarfs like Leo~I can hold on to gas reservoirs and avoid quenching for several Gyrs after falling into their host, which is longer than generally found in simulations. Leo~II, NGC~6822, and IC~10 are also qualitatively consistent with this SF pattern in relation to their orbit, but more tentatively due to larger uncertainties., Comment: 27 pages, 9 Figures, 8 Tables, Submitted to ApJ

A surprising finding of recent studies is the large number of Active Galactic Nuclei (AGN) associated with moderately massive black holes ($\rm \log(M_\bullet/M_\odot)\sim 6-8$), in the first billion years after the Big Bang ($z>5$). In this context, a relevant finding has been the large fraction of candidate dual AGN, both at large separations (several kpc) and in close pairs (less than a kpc), likely in the process of merging. Frequent black hole merging may be a route for black hole growth in the early Universe; however, previous findings are still tentative and indirect. We present JWST/NIRSpec-IFU observations of a galaxy at $z=7.15$ in which we find evidence for a $\rm \log(M_\bullet/M_\odot)\sim7.7$ accreting black hole, as traced by a broad component of H$\beta$ emission, associated with the Broad Line Region (BLR) around the black hole. This BLR is offset by 620 pc in projection from the centroid of strong rest-frame optical emission, with a velocity offset of $\sim$40 km/s. The latter region is also characterized by (narrow) nebular emission features typical of AGN, hence also likely hosting another accreting black hole, although obscured (type 2, narrow-line AGN). We exclude that the offset BLR is associated with Supernovae or massive stars, and we interpret these results as two black holes in the process of merging. This finding may be relevant for estimates of the rate and properties of gravitational wave signals from the early Universe that will be detected by future observatories like LISA., Comment: 12 pages, 5 figures; accepted for publication in MNRAS; doi:10.1093/mnras/stae943

Perhaps the most classical diffusion model for chemotaxis is the Keller-Segel system $\begin{equation} \begin{cases} u_{t} =\Delta u - \nabla \cdot(u \nabla v) \ \ \ \text{in } \mathbb{R}^2\times(0,T),\\[5pt] v = (-\Delta_{\mathbb{R}^2})^{-1} u := \displaystyle\frac {1}{2\pi} \displaystyle\int_{\mathbb{R}^2} \log \frac {1}{|x-z|}u(z,t) dz, \ \ \ \ \ \ \ \ \ (\star)\\[5pt] u(\cdot ,0) = u_{0}^{\star} \ge 0 \ \ \ \text{in } \mathbb{R}^2. \end{cases} \end{equation}$ We show that there exists $\varepsilon>0$ such that for any $m$ satisfying $8\pi

The SPT0311-58 system resides in a massive dark matter halo at z ~ 6.9. It hosts two dusty galaxies (E and W) with a combined star formation rate of ~3500 Msun/yr. Its surrounding field exhibits an overdensity of sub-mm sources, making it a candidate proto-cluster. We use spatially-resolved spectroscopy provided by the JWST/NIRSpec Integral Field Unit (IFU) to probe a field of view (FoV) ~ 17 x 17 kpc^2 around this object. These observations have revealed ten new galaxies at z ~ 6.9, characterised by dynamical masses spanning from ~10^9 to 10^10 Msun and a range in radial velocities of ~ 1500 km/s, in addition to the already known E and W galaxies. The implied large number density, and the wide spread in velocities, indicate that SPT0311-58 is at the core of a proto-cluster, immersed in a very massive dark matter halo of ~ 5 x 10^12 Msun. Hence, it represents the most massive proto-cluster ever found at the EoR. We also study the dynamical stage of the system and find that it likely is not fully virialised. The galaxies exhibit a great diversity of properties showing a range of evolutionary stages. We derive their ongoing Ha-based unobscured SFR, and find that its contribution to the total SF varies significantly across the galaxies in the system. Their ionization conditions range from those typical of field galaxies at similar redshift recently studied with JWST to those found in more evolved objects at lower z. The metallicity spans more than 0.8 dex across the FoV, reaching nearly solar values in some cases. The detailed IFU spectroscopy of the E galaxy reveals that it is actively assembling its stellar mass, showing sub-kpc inhomogeneities, and a metallicity gradient that can be explained by accretion of low metallicity gas from the IGM. The kinematic maps indicate departures from regular rotation, high turbulence, and a possible pre-collision minor merger. (Abridged), Comment: Revised version: minor changes, improved figures, updated references

We present the identification of 42 narrow-line active galactic nuclei (type-2 AGN) candidates in the two deepest observations of the JADES spectroscopic survey with JWST/NIRSpec. The spectral coverage and the depth of our observations allow us to select narrow-line AGNs based on both rest-frame optical and UV emission lines up to z=10. Due to the metallicity decrease of galaxies, at $z>3$ the standard optical diagnostic diagrams (N2-BPT or S2-VO87) become unable to distinguish many AGN from other sources of photoionisation. Therefore, we also use high ionisation lines, such as HeII$\lambda$4686, HeII$\lambda$1640, NeIV$\lambda$2422, NeV$\lambda$3420, and NV$\lambda$1240, also in combination with other UV transitions, to trace the presence of AGN. Out of a parent sample of 209 galaxies, we identify 42 type-2 AGN (although 10 of them are tentative), giving a fraction of galaxies in JADES hosting type-2 AGN of about $20\pm3$\%, which does not evolve significantly in the redshift range between 2 and 10. The selected type-2 AGN have estimated bolometric luminosities of $10^{41.3-44.9}$ erg s$^{-1}$ and host-galaxy stellar masses of $10^{7.2-9.3}$ M$_{\odot}$. The star formation rates of the selected AGN host galaxies are consistent with those of the star-forming main sequence. The AGN host galaxies at z=4-6 contribute $\sim$8-30 \% to the UV luminosity function, slightly increasing with UV luminosity., Comment: 23 pages 13 figures

A {\em vortex pair} solution of the incompressible $2d$ Euler equation in vorticity form $$ \omega_t + \nabla^\perp \Psi\cdot \nabla \omega = 0 , \quad \Psi = (-\Delta)^{-1} \omega, \quad \hbox{in } \mathbb{R}^2 \times (0,\infty)$$ is a travelling wave solution of the form $\omega(x,t) = W(x_1-ct,x_2 )$ where $W(x)$ is compactly supported and odd in $x_2$. We revisit the problem of constructing solutions which are highly $\varepsilon$-concentrated around points $ (0, \pm q)$, more precisely with approximately radially symmetric, compactly supported bumps with radius $\varepsilon$ and masses $\pm m$. Fine asymptotic expressions are obtained, and the smooth dependence on the parameters $q$ and $\varepsilon$ for the solution and its propagation speed $c$ are established. These results improve constructions through variational methods in [14] and in [5] for the case of a bounded domain., Comment: To appear in Journal of Differential Equations. arXiv admin note: substantial text overlap with arXiv:2310.07238

We present a new method for obtaining photometric redshifts (photo-z) for sources observed by multiple photometric surveys using a combination (conflation) of the redshift probability distributions (PDZs) obtained independently from each survey. The conflation of the PDZs has several advantages over the usual method of modelling all the photometry together, including modularity, speed, and accuracy of the results. Using a sample of galaxies with narrow-band photometry in 56 bands from J-PAS and deeper grizy photometry from the Hyper-SuprimeCam Subaru Strategic program (HSC-SSP), we show that PDZ conflation significantly improves photo-z accuracy compared to fitting all the photometry or using a weighted average of point estimates. The improvement over J-PAS alone is particularly strong for i>22 sources, which have low signal-to-noise ratio in the J-PAS bands. For the entire i<22.5 sample, we obtain a 64% (45%) increase in the number of sources with redshift errors |Dz|<0.003, a factor 3.3 (1.9) decrease in the normalised median absolute deviation of the errors (sigma_NMAD), and a factor 3.2 (1.3) decrease in the outlier rate compared to J-PAS (HSC-SSP) alone. The photo-z accuracy gains from combining the PDZs of J-PAS with a deeper broadband survey such as HSC-SSP are equivalent to increasing the depth of J-PAS observations by ~1.2--1.5 magnitudes. These results demonstrate the potential of PDZ conflation and highlight the importance of including the full PDZs in photo-z catalogues., Comment: 15 pages, 16 figures, 1 table. Accepted for publication in A&A

We present a hierarchical Bayesian pipeline, BP3M, that measures positions, parallaxes, and proper motions (PMs) for cross-matched sources between Hubble~Space~Telescope (HST) images and Gaia -- even for sparse fields ($N_*<10$ per image) -- expanding from the recent GaiaHub tool. This technique uses Gaia-measured astrometry as priors to predict the locations of sources in HST images, and is therefore able to put the HST images onto a global reference frame without the use of background galaxies/QSOs. Testing our publicly-available code in the Fornax and Draco dSphs, we measure accurate PMs that are a median of 8-13 times more precise than Gaia DR3 alone for $20.5

This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more km-scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions., Comment: Summary of the Terrestrial Very-Long-Baseline Atom Interferometry Workshop held at CERN: https://indico.cern.ch/event/1208783/

We consider the problem of finding a solution to the incompressible Euler equations $$ \omega_t + v\cdot \nabla \omega = 0 \quad \hbox{ in } \mathbb{R}^2 \times (0,\infty), \quad v(x,t) = \frac 1{2\pi} \int_{{\mathbb R}^2} \frac {(y-x)^\perp}{|y-x|^2} \omega (y,t)\, dy $$ that is close to a superposition of traveling vortices as $t\to \infty$. We employ a constructive approach by gluing classical traveling waves: two vortex-antivortex pairs traveling at main order with constant speed in opposite directions. More precisely, we find an initial condition that leads to a 4-vortex solution of the form $$ \omega (x,t) = \omega_0(x-ct\, e ) - \omega_0 ( x+ ct \, e) + o(1) \ \hbox{ as } t\to\infty $$ where $$ \omega_0( x ) = \frac 1{\varepsilon^{2}} W \left ( \frac {x-q} \varepsilon \right ) - \frac 1{\varepsilon^{2}}W \left ( \frac {x+q} \varepsilon \right ) + o(1) \ \hbox{ as } \varepsilon \to 0 $$ and $W(y)$ is a certain fixed smooth profile, radially symmetric, positive in the unit disc zero outside.

Merger events can trigger gas accretion onto supermassive black holes (SMBHs) located at the centre of galaxies, and form close pairs of AGN. The fraction of AGN in pairs offers critical insights into the dynamics of galaxy interactions, SMBH growth, and their co-evolution with host galaxies. However, the identification of dual AGN is difficult, as it requires high-quality spatial and spectral data; hence, only very few pairs have been found in the distant Universe so far. This study aims to provide a first observational estimate of the fraction of dual AGN at 2

Wrinkling is an $h$-principle technique, introduced by Eliashberg and Mishachev, that can be used to prove statements of the form: "formal solutions of a partial differential relation $\mathcal{R}$ can be deformed to singular/wrinkled solutions". What a wrinkled solution is depends on the context, but the overall idea is that it should be an object that fails to be a solution due to the presence of mild/controlled singularities. Much earlier, Haefliger structures were introduced by Haefliger as singular analogues of foliations. Much like a foliation is locally modelled on a submersion, a Haefliger structure is modelled on an arbitrary map. This implies that Haefliger structures have better formal properties than foliations. For instance, they can be pulled back by arbitrary maps and admit a classifying space. In [8], the second and third authors generalised the wrinkled embeddings of Eliashberg and Mishachev to arbitrary order. This paper can be regarded as a sequel in which we deal instead with generalisations of wrinkled submersions. The main messages are that: 1) Haefliger structures provide a nice conceptual framework in which general wrinkling statements can be made. 2) Wrinkling can be interpreted as holonomic approximation into the \'etale space of solutions of the relation $\mathcal{R}$. These statements imply connectivity statements relating (1) $\mathcal{R}$ to its \'etale space of solutions and (2) the classifying space for foliations with transverse $\mathcal{R}$-geometry to its formal counterpart.

We present NIRSpec IFS observations of a galaxy group around the massive GS_4891 galaxy at z=3.7 in GOODS-South that includes two other two systems, GS_4891_n to the north and GS_28356 to the east. These observations, obtained as part of the GTO GA-NIFS program, allow for the first time to study the spatially resolved properties of the interstellar medium (ISM) and ionized gas kinematics of a galaxy at this redshift. Leveraging the wide wavelength range spanned with the high-dispersion grating (with resolving power R=2700) observations, covering from [OII]$\lambda$$\lambda$3726,29 to [SII]$\lambda$$\lambda$6716,31, we explore the spatial distribution of star-formation rate, nebular attenuation and gas metallicity, together with the mechanisms responsible for the excitation of the ionized gas. GS_4891 presents a clear gradient of gas metallicity (as traced by 12 + log(O/H)) by more than 0.2dex from the south-east (where a star-forming clump is identified) to the north-west. The gas metallicity in the less-massive northern system, GS_4891_n, is also higher by 0.2 dex than at the center of GS_4891, suggesting that inflows of lower-metallicity gas might be favoured in higher-mass systems. The kinematic analysis shows that GS_4891 presents velocity gradients in the ionized gas consistent with rotation. The region between GS_4891 and GS_4891_n does not present high gas turbulence which, together with the difference in gas metallicities, suggests that these two systems might be in a pre-merger stage. Finally, GS_4891 hosts an ionized outflow that extends out to r_out=1.2 kpc from the nucleus and reaches maximum velocities v_out of approximately 400 km/s. Despite entraining an outflowing mass rate of M_out$\sim$2Msun/yr, the low associated mass-loading factor, $\eta$=0.05, implies that the outflow does not have a significant impact on the star-formation activity of the galaxy., Comment: Submitted to Astronomy & Astrophysics on September 25th, 2023

The long-standing paradox of the linear polarization signal of the Na i D1 line was recently resolved by accounting for the atom's hyperfine structure and the detailed spectral structure of the incident radiation field. That modeling relied on the simplifying angle-averaged (AA) approximation for partial frequency redistribution (PRD) in scattering, which potentially neglects important angle-frequency couplings. This work aims at evaluating the suitability of a PRD-AA modeling for the D1 and D2 lines through comparisons with general angle-dependent (AD) PRD calculations, both in the absence and presence of magnetic fields. We solved the radiative transfer problem for polarized radiation in a one-dimensional semi-empirical atmospheric model with microturbulent and isotropic magnetic fields, accounting for PRD effects, comparing PRD-AA and PRD-AD modelings. The D1 and D2 lines are modeled separately as two-level atomic system with hyperfine structure. The numerical results confirm that a spectrally structured radiation field induces linear polarization in the D1 line. However, the PRD-AA approximation greatly impacts the Q/I shape, producing an antisymmetric pattern instead of the more symmetric PRD-AD one, while presenting a similar sensitivity to magnetic fields between 10 and 200 G. Under the PRD-AA approximation, the Q/I profile of the D2 line presents an artificial dip in its core, which is not found for the PRD-AD case. We conclude that accounting for PRD-AD effects is essential to suitably model the scattering polarization of the Na i D lines. These results bring us closer to exploiting the full diagnostic potential of these lines for the elusive chromospheric magnetic fields.

The fermionic Kitaev chain is a canonical model featuring topological Majorana zero modes. We report the experimental realization of its bosonic analogue in a nano-optomechanical network where parametric interactions induce two-mode squeezing and beamsplitter coupling among the nanomechanical modes, equivalent to hopping and superconductor pairing in the fermionic case, respectively. We observe several extraordinary phenomena in the bosonic dynamics and transport, including quadrature-dependent chiral amplification, exponential scaling of the gain with system size, and strong sensitivity to boundary conditions. Controlling the interaction phases and amplitudes uncovers a rich dynamical phase diagram that links the observed phenomena to non-Hermitian topological phase transitions. Finally, we present an experimental demonstration of an exponentially enhanced response to a small perturbation as a consequence of non-Hermitian topology. These results represent the demonstration of a novel synthetic phase of matter whose bosonic dynamics do not have fermionic parallels, and establish a powerful system to study non-Hermitian topology and its applications in signal manipulation and sensing., Comment: 21 pages, 5 figures

Dust-obscured galaxies are thought to represent an early evolutionary phase of massive galaxies in which the active galactic nucleus (AGN) is still deeply buried in significant amounts of dusty material and its emission is strongly suppressed. The unprecedented sensitivity of the James Webb Space Telescope enables us for the first time to detect the rest-frame optical emission of heavily obscured AGN and unveil the properties of the hidden accreting super-massive black holes (BHs). In this work, we present the JWST/NIRSpec IFS data of ALESS073.1, a massive, dusty, star-forming galaxy at $z = 4.76$ hosting an AGN at its center. The detection of a very broad $H_\alpha$ emission associated with the Broad Line Region (BLR) confirms the presence of a BH ($\log(M_{BH}/M_\odot)>8.7$) accreting at less than 15\% of its Eddington limit and classifies the target as a Type 1 AGN. The rest-frame optical emission lines also reveal a fast ionized gas outflow marginally resolved in the galaxy center. The high sensitivity of NIRSpec allows us to perform the kinematic analysis of the narrow H$\alpha$ component which indicates that the warm ionized gas velocity field is consistent with disk rotation. We also find that, in the innermost nuclear regions ($< 1.5$ kpc), the intrinsic velocity dispersion of the disk reaches $\sim 150$ km/s, $\sim 2-3$ times higher than the velocity dispersion inferred from the [CII] 158$\mu$m line tracing mostly cold gas. Since, at large radii, the velocity dispersion of the warm and cold gas are comparable, we conclude that the outflows are injecting turbulence in the warm ionized gas in the central region, but they are not sufficiently powerful to disrupt the dense gas and quench star formation. These findings support the scenario that dust-obscured galaxies represent the evolutionary stage preceding the unobscured quasar when all gas and dust are removed from the host., Comment: 16 pages, 12 figures, accepted in A&A

Massive, starbursting galaxies in the early Universe represent some of the most extreme objects in the study of galaxy evolution. One such source is HFLS3 (z~6.34), which was originally identified as an extreme starburst galaxy with mild gravitational magnification ($\mu$~2.2). Here, we present new observations of HFLS3 with the JWST/NIRSpec IFU in both low (PRISM/CLEAR; R~100) and high spectral resolution (G395H/290LP; R~2700), with high spatial resolution (~0.1") and sensitivity. Thanks to the combination of the NIRSpec data and a new lensing model with accurate spectroscopic redshifts, we find that the 3"x3" field is crowded, with a lensed arc (C, $z=6.3425\pm0.0002$), two galaxies to the south (S1 and S2, $z=6.3592\pm0.0001$), two galaxies to the west (W1, $z=6.3550\pm0.0001$; W2, $z=6.3628\pm0.0001$), and two low-redshift interlopers (G1, $z=3.4806\pm0.0001$; G2, $z=2.00\pm0.01$). We present spectral fits and morpho-kinematic maps for each bright emission line from the R2700 data for all sources except G2. From a line ratio analysis, the galaxies in component C are likely powered by star formation, while we cannot rule out or confirm the presence of AGN in the other high-redshift sources. We perform gravitational lens modelling, finding evidence for a two-source composition of the lensed central object and a comparable magnification factor ($\mu$=2.1-2.4) to previous work. The projected distances and velocity offsets of each galaxy suggest that they will merge within the next ~1Gyr. Finally, we examine the dust extinction-corrected SFR(Ha) of each z>6 source, finding that the total star formation ($510\pm140$Msol/yr, magnification-corrected) is distributed across the six z~6.34-6.36 objects over a region of diameter ~11kpc. Altogether, this suggests that HFLS3 is not a single starburst galaxy, but instead is a merging system of star-forming galaxies in the Epoch of Reionisation., Comment: 27 pages, 17 figures, accepted for publication in A&A

There is compelling evidence that the most massive galaxies in the Universe stopped forming stars due to the time-integrated feedback from their central super-massive black holes (SMBHs). However, the exact quenching mechanism is not yet understood, because local massive galaxies were quenched billions of years ago. We present JWST/NIRSpec integral-field spectroscopy observations of GS-10578, a massive, quiescent galaxy at redshift z=3.064. From the spectrum we infer that the galaxy has a stellar mass of $M_*=1.6\pm0.2 \times 10^{11}$ MSun and a dynamical mass $M_{\rm dyn}=2.0\pm0.5 \times 10^{11}$ MSun. Half of its stellar mass formed at z=3.7-4.6, and the system is now quiescent, with the current star-formation rate SFR<9 MSun/yr. We detect ionised- and neutral-gas outflows traced by [OIII] emission and NaI absorption. Outflow velocities reach $v_{\rm out}\approx$1,000 km/s, comparable to the galaxy escape velocity and too high to be explained by star formation alone. GS-10578 hosts an Active Galactic Nucleus (AGN), evidence that these outflows are due to SMBH feedback. The outflow rates are 0.14-2.9 and 30-300 MSun/yr for the ionised and neutral phases, respectively. The neutral outflow rate is ten times higher than the SFR, hence this is direct evidence for ejective SMBH feedback, with mass-loading capable of interrupting star formation by rapidly removing its fuel. Stellar kinematics show ordered rotation, with spin parameter $\lambda_{Re}=0.62\pm0.07$, meaning GS-10578 is rotation supported. This study shows direct evidence for ejective AGN feedback in a massive, recently quenched galaxy, thus clarifying how SMBHs quench their hosts. Quenching can occur without destroying the stellar disc., Comment: 40 pages, 9 figures, submitted to Nat. Ast., comments welcome!

A limit cycle is a self-sustained periodic motion appearing in autonomous ordinary differential equations. As the period of the limit cycle is a-priori unknown, it is challenging to find them as stationary states of a rotating ansatz. Correspondingly, their study commonly relies on brute-force time-evolution or on circumstantial evidence such as instabilities of fixed points. Alas, such approaches are unable to account for the coexistence of multiple solutions, as they rely on specific initial conditions. Here, we develop a multifrequency rotating ansatz with which we find limit cycles as stationary states. We demonstrate our approach and its performance in the simplest case of the Van der Pol oscillator. Moving beyond the simplest example, we show that our method can capture the coexistence of all fixed-point attractors and limit cycles in a modified nonlinear Van der Pol oscillator. Our results facilitate the systematic mapping of out-of-equilibrium phase diagrams, with implications across all fields of natural science., Comment: Includes Supplemental Material