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Overdense fireworks in GOODS-N: Unveiling a record number of massive dusty star-forming galaxies at
No full textHigh-density environments, such as early galaxy overdensities, play a critical role in hierarchical structure formation and galaxy evolution, providing an ideal setting for accelerated galaxy growth. The GOODS-N overdensity at z ≃ 5.2 has long been known, but its full extent and richness have only recently been revealed by JWST observations. It is highly elongated along the line of sight, spanning nearly 30 cMpc. We investigated its dusty galaxy population using the NIKA2 Cosmological Legacy Survey (N2CLS). Within this overdensity, we identify five luminous dusty starbursts that are spectroscopically confirmed, along with three additional candidates supported by robust photometric redshifts. Three of the spectroscopically confirmed galaxies (N2GN_1_01, 06, and 23, known as GN10, HDF850.1, and S3, respectively) had already been recognised as members of this exceptional structure. We report the discovery of N2GN_1_13 at zspec = 5.182, a massive dusty star-forming galaxy that we confirmed as part of the overdensity through targeted NOEMA follow-up observations of the N2CLS. In addition, by combining our analysis with JWST/FRESCO data, we identified another dusty galaxy at zspec = 5.201 (N2GN_1_61). The eight dusty galaxies are massive (with a median stellar mass of ∼9 × 1010 M⊙) and highly obscured (with a median AV of ∼3.3) and caught in a short-lived yet extreme starburst phase at z ∼ 5.2. Their high star formation rates (with a median of ∼590 M⊙ yr−1), efficient baryon to stellar mass conversion (ϵ★ > 20% for 75% of the sample), and substantial gas reservoirs and dust content suggest rapid evolution and imminent quenching. Six of these galaxies reside in overdense filaments; the remaining two may trace new distinct structures, which will have to be spectroscopically confirmed. These few dusty galaxies dominate the star formation within the overdensity, contributing more than the numerous Hα emitters, and surpassing the cosmic average star formation rate density for this epoch. The presence of numerous very massive, dusty, and intensely star-forming galaxies at z ∼ 5.2 shows that rapid stellar and dust mass assembly was already underway within the first billion years of cosmic history in overdense environments. Their properties, likely driven by efficient gas inflows along cosmic filaments in protocluster regions, suggest an accelerated evolution that current models and simulations have difficulty reproducing
SN 2023gpw: Exploring the diversity and power sources of hydrogen-rich superluminous supernovae
No full textWe present our observations and analysis of SN 2023gpw, a hydrogen-rich superluminous supernova (SLSN II) with broad emission lines in its post-peak spectra. Unlike previously observed SLSNe II, its light curve suggests an abrupt drop during a solar conjunction between ∼80 and ∼180 d after the light curve peak, which is possibly analogous to a normal hydrogen-rich supernova (SN). Spectra taken at and before the peak show hydrogen and helium “flash” emission lines attributed to early interaction with a dense confined circumstellar medium (CSM). A well-observed ultraviolet excess appears as these lines disappear, also as a result of CSM interaction. The blackbody photosphere expands roughly at the same velocity throughout the observations, indicating little or no bulk deceleration. This velocity is much higher than what is seen in spectral lines, suggesting asymmetry in the ejecta. The high total radiated energy (≳9 × 1050 erg) and aforementioned lack of bulk deceleration in SN 2023gpw are difficult to reconcile with a neutrino-driven SN simply combined with efficient conversion from kinetic energy to emission through interaction. This suggests an additional energy source, such as a central engine. While magnetar-powered models qualitatively similar to SN 2023gpw exist, more modeling work is required to determine if they can reproduce the observed properties in combination with early interaction. The required energy might alternatively be provided by accretion onto a black hole created in the collapse of a massive progenitor star
Constraining the outer boundary condition for the Babcock-Leighton dynamo models
No full textContext. The evolution of the Sun’s large-scale surface magnetic field is well captured by surface flux transport models, which can therefore provide a natural constraint on the outer boundary condition (BC) of Babcock–Leighton (BL) dynamo models.
Aims. For the first time, we propose a zero radial diffusion BC for BL dynamo models, enabling their surface field evolution to align consistently with surface flux transport simulations.
Methods. We derived a zero radial diffusion BC from the magnetohydrodynamic induction equation and evaluated its effects in comparison with two alternatives: (i) a radial outer BC and (ii) a radial outer BC combined with strong near-surface radial pumping. The comparison was made both for the evolution of a single bipolar magnetic region and within a full BL dynamo model.
Results. The zero radial diffusion outer BC effectively suppresses radial diffusion across the surface, ensuring consistency between the evolution of the bipolar magnetic region in the BL dynamo and the surface flux transport model. With this outer BC, the full BL dynamo model successfully reproduces the fundamental properties of the solar cycle. In addition, the model naturally produces a surface magnetic field that is not purely radial, in closer agreement with solar observations.
Conclusions. The physically motivated zero radial diffusion BC paves the way for deeper insight into the solar and stellar cycles
Direct calculation of steady-state hydrodynamic solar wind solutions with newtonian viscosity
No full textContext. Steady-state solutions to the Navier-Stokes equations are a valuable tool for constructing quasi-steady models of the solar wind and exploring the various factors that affect the fluxes of mass, energy, and momentum into the heliosphere. These models typically omit the effects of viscosity, which is assumed to be negligible under most coronal and heliospheric conditions; however, the inviscid Navier-Stokes equations are known to admit solutions that are singular at the sonic point, where the solar wind speed becomes equal to the relevant acoustic speed. Consequently, inviscid solar wind models require special treatment of the solution near the sonic points, and this has proven to be a significant impediment to efficient modeling of the solar wind.
Aims. In this paper we revisit the governing hydrodynamic equations for the expanding solar wind, with the inclusion of the viscous stress as defined by the classical (Newtonian) closure, and we show how this inclusion eliminates the singularities that emerge from the inviscid equations. This result has been previously reported and used to generate steady-state solar wind profiles from initial conditions in the asymptotic limit (outside of the Sun’s gravitational well); however, those studies did not include realistic treatments of the inner corona, and generally rejected the prospect of extrapolating solutions outward from the Sun into the heliosphere, which they deemed to be computationally unfeasible. Our aim, therefore, is to expand this method to include external heating and optically thin radiative losses and show that solutions can be computed outward from initial conditions near the solar surface, thereby capturing the entire range of scales from below the transition region to the outer heliosphere in a single solution.
Methods. Our approach was to cast the steady-state, field aligned Navier-Stokes equations as a system of five coupled, first order, ordinary differential equations (ODEs) describing the spatial evolution of the mass density, pressure, speed, conductive heat flux, and viscous stress. These equations were then solved using conventional methods, without any special treatment of the governing equations in the vicinity of the sonic point. Physically meaningful solutions were identified by varying the initial conditions at the lower boundary until the solution obtained the correct asymptotic form, which we derived for the particular closures that we employed.
Results. The representative solutions that we present here demonstrate the utility and efficiency of this extrapolation method, which is considerably more realistic than commonly used analytical or empirical models. This method provides a direct approach to generating accurate solar wind profiles subject to observationally motivated initial conditions near the solar surface, at a fraction of the computational cost of comparable relaxation-based models. The solutions obtained from this method can be used to initialize time-dependent simulations, to generate large families of steady-state solutions that can then be used to populate the hydrodynamic variables along individual magnetic field lines in global magnetic field models, and to explore how the properties of the quasi-steady solar wind are affected by changes in magnetic geometry and different coronal heating models
How internal structure shapes the metallicity of giant exoplanets
No full textContext. The composition and internal structure of gas giant exoplanets encode key information about their formation and evolution.
Aims. We investigate how different assumed interior structures affect the inferred bulk metallicity and its correlation with planetary mass.
Methods. For a sample of 44 giant exoplanets (0.12–5.98 MJ), we computed evolutionary models with CEPAM and retrieved their bulk metallicities under three structural hypotheses: core+envelope (CE), dilute core (DC), and fully mixed (FM).
Results. Across all structures, we recover a significant positive correlation between total heavy-element mass (MZ) and planetary mass (M), and a negative correlation between bulk metallicity (Z) and M (also for Z/Z⋆ vs M). Dilute core structures yield metallicities comparable to CE models, regardless of the assumed extent of the composition gradient. Increasing atmospheric metallicity augments the inferred bulk metallicity, as enhanced opacities slow planetary cooling. Non-adiabatic DC models can further increase the retrieved metallicity by up to 35%. We find that the mass–metallicity anti-correlation is primarily driven by low-mass, metal-rich planets (M < 0.2 MJ), and that massive planets (≳ 1 MJ) can exhibit unexpectedly high metallicities (Z ~ 0.1–0.3).
Conclusions. Improved constraints on convective mixing, combined with upcoming accurate measurements of planetary masses, radii, and atmospheric compositions from missions such as PLATO and Ariel, will provide further constraints on interior structure and formation models of gas giant planets
Environmental invariance of the galaxy size–mass relation
No full textContext. The galaxy size-luminosity and size-stellar mass relations are important constraints on the galactic baryon cycle of gas accretion, star formation, and feedback. There are conflicting claims in the literature regarding how an environment influences size, and both “direct” transformative effects and “assembly bias” may contribute to observed variations with environment.
Aims. We constructed a large homogeneous sample of size measurements to Mr ∼ −14 (M★ ∼ 107 M⊙). Our sample fills a gap in field galaxy size measurements around ∼107 − 108 M⊙; the literature at these masses is biased toward satellites of L★ galaxies and members of galaxy clusters.
Methods. We used sizes from the DESI Legacy Survey (DESI-LS; which is significantly larger and deeper than SDSS) together with a published catalog that contains stellar masses and cluster positions derived from DESI-LS photometry. Our sample extends to z < 0.3 and comprises 540 228 galaxies with spectroscopic redshifts and 9 513 732 galaxies with photometric redshifts. We explored the environmental dependence of size for a mass-limited subset of our sample at z < 0.05 based on the distance to the nearest cluster center.
Results. We obtained size-luminosity and size-mass relations in good agreement with previous studies. By separating galaxies according to color and morphology, we show that the environmental variation of the overall size-mass relation on megaparsec scales can be understood as the consequence of a changing mixture of subpopulations, rather than “direct” size transformation. For example, at a fixed mass, quiescent (red) late-type galaxies within 2 Mpc of a cluster have the same size as quiescent late-type galaxies 30 Mpc from the nearest cluster.
Conclusions. Our results support individual galaxy assembly histories as the primary determinant of galaxy size. The existence of significantly different environment-insensitive size-mass relations for subpopulations separated by color (star formation rate) and Sérsic index (morphology) provides a clear target for calibration of the baryon cycle in cosmological simulations
The Galaxy Activity, Torus, and Outflow Survey (GATOS)
No full textThe distribution of molecular gas on small scales regulates star formation and the growth of supermassive black holes in galaxy centers. Yet, the role of active galactic nuclei (AGN) feedback in shaping this distribution remains poorly constrained. We investigate how AGNs influence the small-scale structure of molecular gas in galaxy centers by measuring the clumpiness of CO(3 − 2) emission observed with the Atacama Large Millimeter/submillimeter Array (ALMA) in the nuclear regions (50 − 200 pc from the AGNs) of 16 nearby Seyfert galaxies from the Galaxy Activity, Torus, and Outflow Survey (GATOS). To quantify clumpiness we applied three different methods: (1) the median of the pixel-by-pixel contrast between the original and smoothed maps; (2) the ratio of the total excess flux to the total flux, after subtracting the background smoothed emission; and (3) the fraction of total flux coming from clumpy regions, interpreted as the mass fraction in clumps. We find a negative correlation between molecular gas clumpiness and AGN X-ray luminosity (LX), suggesting that higher AGN activity is associated with smoother gas distributions. All methods reveal a turnover in this relation around LX = 1042 erg s−1, possibly indicating a threshold above which AGN feedback becomes efficient at dispersing dense molecular structures and suppressing future star formation. Our findings provide new observational evidence that AGN feedback can smooth out dense gas structures in galaxy centers
Interstellar medium phases and abundances in the central parsec
No full textContext. The Galactic center (GC) is a unique and extreme astrophysical laboratory for studying the interplay between gas, stars, and a supermassive black hole (SMBH). In particular, the circumnuclear disk (CND) and its central cavity (CC) present two contrasting environments in terms of gas content, density, and stellar activity, making them ideal regions in which to study the multiphase structure and chemical composition of the interstellar medium (ISM).
Aims. We aim to determine the properties (temperature, density, abundances, and spatial distribution) of the various phases of the ISM in the central parsec of the GC, with particular attention in this paper to the ionized medium.
Methods. We used newly obtained observations from the Mid-Infrared Instrument (MIRI) equipped with the Medium Resolution Spectrometer (MRS) aboard the James Webb Space Telescope (JWST) to extract spectra covering the entire spectral range from 5 to 27 µm in the CND and in the CC. We used the photoionization code CLOUDY to generate synthetic spectra with the same spectral range and resolution, simulating a wide range of gas phases and abundances. We then determined the contribution of each phase to the spectra. Once the abundances and contribution from each phase of the gas were determined, we identified four dominant phases and performed a spatial analysis to determine their contribution to each spaxel of the datacubes.
Results. We find that in both the CND and the CC, the bulk of the emission originates from warm ionized gas with temperatures of between 104 and 104.8 K. In the CND, molecular gas contributes significantly to the flux and is spatially structured, while the CC shows minimal molecular gas content, as is expected from these regions. Coronal gas is detected in both regions at the interface between molecular and warm ionized gas. The hottest coronal phase appears faint and patchy in the CC, and has an elongated morphology in the CND. Abundance fitting (in solar-normalized logarithmic units) is primarily constrained by abundances: we measure a robust depletion of Fe relative to α elements with log(Fe/α) = −0.78 ± 0.20 (CC) and −0.84 ± 0.26 (CND), while CNO is only mildly enhanced relative to α, log(CNO/α) = 0.27 ± 0.20 (CC) and 0.05 ± 0.26 (CND). Absolute abundances are supersolar but more degenerate; the best-fitting models yield (log α, log CNO, log Fe) = (1.4, 1.4, 0.4) in the CC and (2.0, 1.8, 1.2) in the CND.
Conclusions. The observed abundance pattern (enhanced CNO and α elements with suppressed Fe) indicates a chemically young environment, recently enriched by core-collapse supernovae and stellar winds, with a limited contribution from older Type Ia supernovae. This favors a scenario of massive, recent star formation rather than cumulative long-term enrichment. Additionally, the projected orientation of the newly identified CND elongated hot coronal feature, perpendicular to the direction toward the SMBH, suggests the action of a large-scale shock possibly resulting from past energetic outflows
Impact of active galactic nuclei and nuclear star formation on the ISM turbulence of galaxies: Insights from JWST/MIRI spectroscopy
No full textActive galactic nuclei (AGNs), star formation (SF), and galaxy interactions can drive turbulence in the gas of the interstellar medium (ISM), which, in turn, plays a role in SF taking place within galaxies. The impact on molecular gas is of particular importance, as it serves as the primary fuel for SF. Our goal is to investigate the origin of turbulence and the emission of molecular gas, as well as low-and-intermediate-ionisation gas, in the inner few kpc of both AGN hosts and star-forming galaxies (SFGs). We used archival JWST MIRI/MRS observations of a sample consisting of 54 galaxies at z < 0.1. We present flux measurements for the H2 S(5)λ6.9091 μm, [ArI
Magnetic fields in galactic environments probed by fast radio bursts
No full textFast radio bursts (FRBs) are extragalactic, bright, millisecond radio pulses emitted by unknown sources. FRBs constitute a unique probe of various astrophysical and cosmological environments via their characteristic dispersion (DM) and Faraday rotation (RM) measures that encode information about the ionised gas traversed by the radio waves along the FRB line of sight. In this work, we analysed the observed RM measured for 14 localised FRBs in the 0.05 ≲ zfrb ≲ 0.5 redshift range, in order to infer the total magnetic field, B, in various galactic environments. Additionally, we calculated fgas – the average fraction of baryons in the ionised CGM. We built a spectroscopic dataset of FRB foreground galaxy halos, acquired with VLT/MUSE observations and by the FLIMFLAM collaboration. We developed a novel Bayesian statistical algorithm and used it to correlate information on the individual intervening halos with the observed RMobs. This approach allowed us to disentangle the magnetic fields present in various environments traversed by the FRB sight lines. Our analysis yields the first direct FRB constraints on the strength of magnetic fields in the interstellar medium (ISM) () and in the halos () of FRB host galaxies, as well as in the halos of foreground galaxies and groups (). Assuming no field reversals, we find that the average magnetic field strength in the ISM of the FRB host galaxies is B_{\mathrm{host}}^{\mathrm{local}} = 5.4^{+1.1}_{-0.9}\,{\upmu} G. Additionally, we placed an upper limit on the average magnetic field strength in FRB host halos, B_{\mathrm{host}}^{\mathrm{halo}} \lesssim 4.8\,{\upmu} G, and in foreground intervening halos, B_{\mathrm{fg}}^{\mathrm{halo}} \lesssim 4.3\,{\upmu} G. Moreover, we estimated the average fraction of cosmic baryons inside 10 ≲ log10(Mhalo/M⊙) ≲ 13.1 halos to be . We find that the magnetic field strengths inferred in this work are in good agreement with previous measurements. In contrast to previous studies that analysed FRB RMs and have not considered contributions from the halos of the foreground and/or FRB host galaxies, we show that halos can contribute a non-negligible amount of RM and must be taken into account when analysing future FRB samples