arXiv subjects

Giulia Rodighiero

Publications and source records attributed to Giulia Rodighiero.

At least 19 recordsLinked to original sources

arXiv2026

Gamma-ray bursts reveal the history and faint contributors of cosmic reionization

Star-forming galaxies are generally believed to be the main drivers of cosmic reionization. However, the relative contributions of bright and faint galaxies to this process remain unclear. As the most luminous transient phenomena in the universe, long gamma-ray bursts (LGRBs) provide a unique opportunity to probe star formation occurring in both detectable and undetectable galaxies. In this Letter, we present new estimates of the cosmic star formation rate density (SFRD) at $4<z<10$ using Swift LGRBs detected over the past two decades, by considering LGRBs as unbiased tracers of total star formation at high redshifts. Crucially, we find that the new LGRB-inferred SFRD can naturally explain current measurements of hydrogen reionization without invoking extreme ionizing photon production efficiencies or escape fractions from galaxies. Using these LGRB-inferred SFRD values, we further investigate the faintest magnitude limits of high-redshift galaxies, finding a redshift evolution of the limiting magnitudes from $M_{\mathrm{lim}}\sim-14$ to $-15$ at $z\sim6$ to $M_{\mathrm{lim}}\sim-10$ to $-11$ at $z\sim10$. This result provides one independent piece of evidence for the presence of a large population of faint galaxies at redshifts $z\gtrsim6$, as an important complement to our understanding of the ionizing photon budget in the early universe.

astro-ph.CO↗

arXiv2026

GREX-PLUS Science Book v2

GREX-PLUS (Galaxy Reionization EXplorer and PLanetary Universe Spectrometer) is a mission candidate for a JAXA strategic L-class mission to be launched in the 2030s. Its primary science goals are two-fold: galaxy formation and evolution, and planetary system formation and evolution. The GREX-PLUS spacecraft will carry a telescope with a 1 m primary mirror aperture cooled down to 50 K. The two science instruments will be onboard: a wide-field camera in the 2--8 $\mu$m wavelength band and a high-resolution spectrometer with a wavelength resolution of 30,000 in the 10--18 $\mu$m band. The GREX-PLUS wide-field camera aims to detect the first generation of galaxies at redshift $z>15$. The GREX-PLUS high-resolution spectrometer aims to identify the location of the water ``snowline'' in protoplanetary disks. Both instruments will provide unique datasets for a broad range of scientific topics, including galaxy mass assembly, the origin of supermassive blackholes, infrared background radiation, molecular spectroscopy in the interstellar medium, transit spectroscopy of exoplanet atmospheres, planetary atmospheres in the Solar System, and so on. This document is the second version of a collection of scientific themes that can be achieved with GREX-PLUS. Each section in Chapters~2 and 3 is based on presentations at several GREX-PLUS Science Workshops.

astro-ph.IM↗

arXiv2026

Gas Fraction and Depletion Time Drive the Main-Sequence Scatter in Massive Galaxies at $z\sim1.5$

We present ALMA Band 7 dust continuum observations of 57 massive ($M_\ast \gtrsim 10^{10.8}~M_\odot$) star-forming galaxies at $1.45 3\sigma$ detections for 55 galaxies. Combining the ALMA data with multiwavelength photometry, we reliably derive dust masses and infer molecular gas masses using metallicity-dependent gas-to-dust ratios estimated from individual metallicity measurements. The derived molecular gas mass ratio spans $\mu_\mathrm{gas} = M_\mathrm{gas}/M_\ast=0.11\text{--}2.8$, with a median value of 0.65, corresponding to gas reservoirs more than an order of magnitude larger than in local galaxies at fixed stellar mass. The integrated Schmidt--Kennicutt relation is consistent with previous measurements over $z=0\text{--}2$. Across the MS, both molecular gas mass ratio and star formation efficiency scale approximately as $(\mathrm{sSFR}/\mathrm{sSFR}_\mathrm{MS})^{0.5}$, indicating that the MS scatter is driven nearly equally by variations in gas content and depletion time. The intrinsic scatter of $0.19$~dex suggests additional galaxy-to-galaxy diversity in star formation efficiency. Our results provide a controlled test of the unified gas scaling framework in the massive regime at $z\sim1.5$, demonstrating that the fundamental regulation of star formation through coupled modulation of gas supply and efficiency is already in place at cosmic noon.

astro-ph.GA↗

arXiv2026

A first empirical derivation of the average dust attenuation law at 2<z<7

Dust attenuation strongly affects the observed spectral energy distributions of galaxies, introducing significant uncertainties in the derivation of key physical properties such as star formation rates, stellar masses, and metallicities. While attenuation curves have been extensively studied in the local Universe and at intermediate redshift, direct spectroscopic constraints at earlier cosmic epochs have remained limited prior to JWST. We aim to derive the average dust attenuation law of star-forming galaxies over the redshift range 2 9) of 120 galaxies with reliable Balmer decrement (Ha/Hb), we construct stacked spectral energy distributions in bins of Balmer optical depth and derive the selective attenuation curve following the empirical methodology introduced by Calzetti et al. (2000). The wavelength coverage is further extended toward the near-infrared using MIRI photometry. The resulting attenuation curve spans the rest-frame range 0.16-1.14mu and is well described by a smooth function. We derive a normalization factor R_V=3.98, finding that the average attenuation law is consistent with the local starburst relation in both slope and normalization. Compared to several determinations at intermediate redshift, however, our curve appears systematically flatter in the ultraviolet. We find no significant evidence for a 2175A UV bump in the average attenuation curve. Our results provide the first empirical determination of the average dust attenuation law for star-forming galaxies at 2<z<7 based on JWST spectroscopy. Despite the diversity of attenuation properties observed in individual systems, the ensemble-average behavior remains consistent with the local starburst relation.

astro-ph.GA↗

arXiv2026

EGS-z11-R0: a red, dust-rich galaxy at Cosmic Dawn

Context. Galaxies discovered by JWST at z > 10 are predominantly characterized by extremely blue rest-frame UV slopes. Conversely, the existence of dust-reddened systems at such early epochs has remained largely unconfirmed spectroscopically. Aims. We present the spectroscopic confirmation of EGS-z11-R0 at z = 11.45, the most distant red galaxy identified to date, discovered serendipitously through inspection of publicly available JWST/NIRSpec data. Methods. We analyze JWST/NIRSpec PRISM and G395M spectroscopy together with multiwavelength HST, NIRCam, and MIRI photometry. We identify significant detections of the C IV 1548,1551 and C III] 1908 transitions, yielding a redshift of zspec = 11.452 +/- 0.021. We measure rest-frame UV emission-line fluxes and equivalent widths and use these diagnostics to constrain the nature of the ionizing radiation field. Finally, we perform spectral energy distribution modeling with CIGALE, combining spectroscopy with photometry and including stellar, nebular, dust, and active galactic nuclei (AGN) components. Results. EGS-z11-R0 exhibits a red UV continuum slope (betaUV approximately -1.0), placing it well above the canonical MUV-betaUV relation at z~10-12 and making it the highest-z spectroscopically confirmed member of the emerging "red monster" population. Emission-line diagnostics reveal a hard ionizing spectrum consistent with extreme star formation and compatible with a composite stellar plus AGN scenario. The best-fit SED solution favors a stellar mass of log(M*/Msun) ~ 9.2-9.6, a SFR of 10-40 Msun yr^-1, and substantial dust attenuation (AV~1.2 mag). Conclusions. The confirmation of EGS-z11-R0 establishes that chemically evolved, dust-enriched galaxies were already in place at z approximately 11.5. [abridged]

astro-ph.GA↗

arXiv2025

ALMA and JWST Identification of Faint Dusty Star-Forming Galaxies up to z~8

We exploit a new sample of around 400 bright dusty galaxies from the ALMA CHAMPS Large Program, together with the rich JWST multi-band data products in the COSMOS field, to explore and validate new selection methods for identifying dusty star-forming galaxies (DSFGs). Here, we present an effective empirical selection criterion based on a newly defined parameter: I_star = log(M_star) x log(SFR). Incorporating the F277W-F444W color as a second parameter further improves the purity of the selection. We then apply this method to the COSMOS2025 catalog to search for fainter dusty galaxy candidates below the ALMA CHAMPS detection limit and, through a stacking technique, identify a population of high-redshift (z=6-8) DSFGs with an average flux density of$S_1.2mm = 0.15uJy and a space density of ~6E-6 Mpc^-3. This faint population seems to have been missed by most of the previous submillimeter/millimeter surveys, and ground- and space-based UV-to-NIR surveys. Finally, we discuss the possibility of an evolutionary connection between the z > 10 UV-bright galaxies recently discovered by JWST, the faint dusty z=6-8 galaxies identified here, and the population of z=3-5 massive quiescent galaxies, potentially linked as progenitor-descendant populations based on their abundance, redshifts, and stellar masses.

astro-ph.GA↗

arXiv2025

Why the Northern Hemisphere Needs a 30-40 m Telescope and the Science at Stake: Cosmology and High-z Universe

Full sky coverage with 30-40 meter-class telescopes is essential to answer fundamental questions in Astrophysics, Cosmology, and Physics, such as the composition of the Universe and the formation of the first stars and supermassive black holes. An ELT/TMT-like telescope in the Northern Hemisphere is a fundamental and necessary facility to provide multiplexing of observing power, diversity of instrumentation, rapid response, and statistical power required to address the questions and the problems, current and future, unveiled by full sky observatories such as JWST, Euclid, or Roman space telescopes. The Northern ELT/TMT will expedite the study of unique, extreme, rare, transient, and/or high-energy events which will give the most information about fundamental Physics problems in the era of multi-messenger and time-domain Astronomy.

astro-ph.IM↗

arXiv2025

Spatially resolved PAH$_{3.3}$ emission and stellar ages in ram pressure stripped clumps at $z\sim0.3$

Ram pressure stripping (RPS) plays a crucial role in shaping galaxy evolution in dense environments, yet its impact on the molecular and dusty phases of the interstellar medium remains poorly understood. We present JWST/NIRCam $3.3\mathrm{\mu m}$ polycyclic aromatic hydrocarbon (PAH) emission maps for the nine most striking RPS galaxies in the Abell 2744 cluster at redshift $z_{cl}=0.306$, tracing the effects of environmental processes on small dust grains. Exploiting multi-band JWST/NIRCam and HST photometry, we performed a spatially resolved ultraviolet (UV) to mid-infrared (MIR) spectral energy distribution (SED) fitting to characterise stellar populations in both galactic disks and clumps detected in the stripped tails. We detected PAH$_{3.3}$ emission in eight of the nine galaxies at $5\sigma$, with morphologies revealing disk truncation and elongation along the RPS direction. In three galaxies, PAH$_{3.3}$ emission is also found in star-forming clumps embedded in the stripped tails up to a distance of $40\mathrm{kpc}$. Star formation rates inferred from PAH$_{3.3}$ emission are in agreement with those derived from SED fitting averaged over the past $100\mathrm{Myr}$ within an intrinsic scatter of $0.4\mathrm{dex}$, but the relation appears to be age-dependent. The spatial correlation between the PAH strength, stellar age, and star formation rate (SFR) is consistent across disks and tails and demonstrates that PAH-carrying molecules can survive and become stripped by ram pressure. Finally, age gradients revealed by the SED fitting provide observational evidence of the fireball model in star-forming, stripped clumps of galaxies at $z \sim 0.3$. This work represents the first detailed study of PAH emission in cluster galaxies, offering new insights into the fate of dust and star formation in extreme environments.

astro-ph.GA↗

arXiv2025

The ALPINE-CRISTAL-JWST Survey: Stellar and nebular dust attenuation of main-sequence galaxies at z~4-6

Characterizing dust attenuation is crucial for revealing the intrinsic physical properties of galaxies. We present an analysis of dust attenuation in 18 spectroscopically confirmed star-forming main-sequence galaxies at $z = 4.4-5.7$ observed with JWST/NIRSpec IFU and NIRCam, selected from the ALPINE and CRISTAL ALMA large programs. We fit the emission line fluxes from NIRSpec and the broad-band photometry from NIRCam with Prospector, using both spatially integrated emission and $\sim0.6$ kpc pixel-by-pixel measurements. We derive the stellar-to-nebular dust attenuation ratio ($f=E(B-V)_{\mathrm{star}}/E(B-V)_{\mathrm{neb}}$) from the SED fits and the Balmer decrement with H$\alpha$ and H$\beta$. Although individual galaxies show large scatter, the best-fit value is $f = 0.51^{+0.04}_{-0.03}$, slightly higher than that measured for local starburst galaxies. We find weak correlations of $f$ with galaxy properties, increasing with higher specific star-formation rates, younger stellar ages, and more recent star-formation. For the range of $E(B-V)_{\mathrm{star}} = 0.009-0.15$ mag for in our sample, assuming $f = 1$ (often adopted in high-redshift studies) instead of $f = 0.51$ underestimate line luminosities and ionizing photon production efficiency $\xi_\text{ion}$ by $\sim3-36\%$ and $\sim4-46\%$, respectively. We also find that the total stellar masses estimated from spatially-integrated SED fits with a delayed-$\tau$ star-formation histories are systematically smaller than the sum of pixel-by-pixel SED fits, with a median offset of $\sim 0.26$ dex, likely because the integrated fits are biased toward luminous young stellar populations.

astro-ph.GA↗

arXiv2025

The $M_{\rm BH}-M_{*}$ Relationship at $3<z<7$: Big Black Holes in Little Red Dots

JWST has identified a large population of faint, broad-line active galactic nuclei (AGN) in the early universe that are powered by black holes (BHs) that often appear overmassive relative to their host galaxies. In this study, we examine the relationship between BH mass and galaxy stellar mass at $3 3\sigma$ above the relationship measured for local broad-line AGN. We derive an intrinsic scatter in this relationship of $0.9$ dex, which does not vary over the redshift range of our sample. We also find that the $M_{\rm BH}/M_{\star}$ ratio increases by $2.3$ dex from $z = 3.5$ and $z = 6.5$ with a confidence level of $ > 3\sigma$. We attribute this trend with the increasing fraction of LRDs in our sample at $z>4$ as their host masses are $\sim1$ dex lower than the non-LRD AGN in our sample. These results support a picture in which the BHs powering JWST's broad-line AGN are genuinely overmassive and become increasingly so with redshift. We discuss the implications of our findings on early BH growth relative to that of their host galaxies and the constraints it places on BH seeding models.

astro-ph.GA↗

arXiv2025

ALMA reveals diverse dust-to-gas mass ratios and quenching modes in old quiescent galaxies

Recent discoveries of dust and molecular gas in quiescent galaxies (QGs) up to $z\sim3$ challenge the long-standing view that the interstellar medium depletes rapidly once star formation ceases, raising key questions of whether dust and gas co-evolve in QGs, and how their depletion links to stellar aging. We present deep Atacama Large Millimeter/submillimeter Array (ALMA) Band~6 continuum and CO(3--2) observations of 17 QGs at $z\sim0.4$ in the COSMOS field. Using the dust-to-molecular gas mass ratio ($\delta_{\rm DGR}$) as a key diagnostic, we trace post-quenching evolution of the cold interstellar medium. Our study triples the number of QGs with direct $\delta_{\rm DGR}$ estimates, constraining 12 systems with stellar population ages of $\sim$5--10 Gyr. For the first time, we show that $\delta_{\rm DGR}$ in QGs ranges from $\sim8\times$ below to $\sim2.5\times$ above the canonical value of $\delta_{\rm DGR}\sim1/100$. Despite uniformly low molecular gas fractions (median $f_{\rm H_2}=M_{\rm H_2}/M_{\star}\sim4.1\%$), QGs follow diverse evolutionary paths: about half exhibit rapid ($\sim700$ Myr) exponential dust decline with age, while the rest show mild decline over $\gtrsim$2 Gyr, maintaining elevated $\delta_{\rm DGR}\gtrsim1/100$. Our results support simulations predictions of dust and molecular gas evolving independently post-quenching, without a preferred quenching mode. This challenges the use of dust continuum as a $\rm H_2$ tracer, implying that quenching cannot be robustly linked to interstellar medium conditions when relying solely on dust or gas.

astro-ph.GA↗

arXiv2025

Need for PRIMA to understand the nature and ISM physical conditions of HST-dark galaxies

One of the main open issues in galaxy formation and evolution is the early assembly of the most massive galaxies and their contribution to the stellar mass and star formation rate densities at early epochs. Massive red sources already in place at z > 2 to 3 have been found in deep Spitzer-IRAC and ALMA surveys. They are often called optically and near-IR dark, or HST-dark, being undetected even in the deepest HST frames. The submillimeter (i.e., ALMA) detection of these sources confirms their high-z dusty nature: they are massive (e.g., log(M*/Msun) > 10) and dusty star-forming galaxies with estimated redshifts in the 2.5 to 7 range. They seem to lie mostly below the main sequence (MS) of star-forming galaxies and show gas depletion times <1 Gyr. Imaging with the PRIMA/PRIMAger instrument over the full 25 to 265 micron range will allow us to characterize their still uncovered spectral energy distributions between JWST and ALMA spectral windows, probing their dust content and properties (e.g., temperature, mass), whereas spectroscopic observations with FIRESS will be the key to investigate the nature of their powering source (e.g., AGN or star formation) and to study the physics of their ISM, by detecting and measuring fine structure lines in the mid- and far-IR domain.

astro-ph.GA↗

arXiv2025

Mysteries of Capotauro: investigating the puzzling nature of an extreme F356W-dropout

JWST has uncovered a diverse population of extreme near-infrared dropouts, including ultra high-redshift ($z>15$) galaxy candidates, dust-obscured galaxies challenging dust production theories, sources with strong Balmer breaks - possibly compact AGN in dense environments - and cold, sub-stellar Galactic objects. This work presents Capotauro, a F356W-dropout in the CEERS survey with F444W AB magnitude of $\sim27.68$ and a sharp $>3$ mag flux drop between $3.5{-}4.5\,\mu$m, undetected below $3.5\,\mu$m. We combine JWST/NIRCam, MIRI, and NIRSpec/MSA data with HST/ACS and WFC3 observations to perform a spectro-photometric analysis of Capotauro using multiple SED-fitting codes. Our setup tests $z\geq15$ as well as $z<10$ dusty, Balmer-break or strong-line galaxy solutions, and the possibility of Capotauro being a Milky Way sub-stellar object. Among extragalactic options, our analysis favors interpreting the sharp drop as a Lyman break at $z\sim32$, consistent with the epoch of formation of the first stars and black holes, with only $\sim0.5\%$ of the posterior volume at $z<25$. Lower-redshift solutions struggle to reproduce the extreme break, suggesting that if Capotauro lies at $z<10$, it must show a non-standard combination of strong dust attenuation and/or Balmer breaks, making it a peculiar interloper. Alternatively, its properties match a very cold (Y2-Y3 type) brown dwarf or a free-floating exoplanet with a record-breaking combination of low temperature and large distance ($T_{\mathrm{eff}}<300\,\mathrm{K}$, $d\gtrsim130\,\mathrm{pc}$, up to $\sim2\,\mathrm{kpc}$). While current data cannot determine its nature, Capotauro emerges as a remarkably unique object in all plausible scenarios, and a compelling target for follow-up.

astro-ph.GA↗

arXiv2025

Sieging HELM's deep: PRIMA unveils the far-infrared properties of highly extincted low-mass galaxies

Although the majority of star-forming galaxies show a tight correlation between stellar mass and dust extinction, recent James Webb Space Telescope observations have revealed a peculiar population of Highly Extincted Low-Mass (HELM) galaxies, which could revolutionise our understanding of dust production mechanisms. To fully understand the dust content of these galaxies, which are a minority of the overall galaxy population, far-infrared observations over large areas are pivotal. In this paper, we derive the expected PRIMAger, the far-IR (24-235$\mu m$) imaging camera proposed for the Probe far-IR Mission for Astrophysics, fluxes for a set of photometric candidates HELM galaxies. Taking into account a deep survey of 1000h over $1\rm\, deg^{2}$, we expect to detect around $3.1 \times 10^4$ HELM sources in at least one PRIMAger filter, 100 of which are at z=1-1.5. For 32% of this sample, there will be observations in at least four PRIMAger filters, covering at least the 90 to $240\mu m$ wavelength range, which will allow us to obtain a detailed fit of the dust emission and estimate the dust mass.

astro-ph.GA↗

arXiv2025

Spatially resolved gas-phase metallicity at z~2-3 with JWST/NIRISS

Spatially resolved gas-phase metallicity maps are a crucial element in understanding the chemical evolution of galaxies. We present spatially resolved metallicity maps obtained from NIRISS/WFSS observations. This is the first such work presenting multiple individual galaxies. We investigate the source of ionisation, metallicity and its relation to star-formation in a spatially-resolved sense for a sample of eight galaxies -- four from JWST-PASSAGE and four from GLASS-JWST ERS. All but one galaxy are in the redshift range $1.9 \leq z \leq 2$, the outlier being at $z = 3.1$. Our sample covers a range of $8.0 <$ \logM $< 9.5$ in stellar mass, $0.2 <$ $\log{\rm{(SFR}}$/\Msunpyr) $< 1.1$ in star-formation rate (SFR) and $7.8 <$ \logOH $< 9.0$ in global metallicity. As a solution to the challenge of SF-AGN demarcation in absence of resolved \halpha, we present a new SF-demarcation line in the \textit{OHNO} parameter space based on MAPPINGS v5.1 publicly available \hii region model grids. We present the mass-metallicity gradient relation for our sample, which showed no clear trend with stellar mass, perhaps hinting at the fact that the high-$z$ galaxies have not yet started their accretion dominated phase. By interpreting the correlation between spatially resolved metallicity and SFR maps as a proxy for effective timescales of metal-transport in galaxies, we find a weak trend such that this timescale increases with stellar mass, implying a more effective feedback in lower mass galaxies.

astro-ph.GA↗

arXiv2025

Semi-empirical constraints on the HI mass function of star-forming galaxies and $\Omega_{\rm HI}$ at $z\sim 0.37$ from interferometric surveys

The HI mass function is a crucial tool to understand the evolution of the HI content in galaxies over cosmic times. We aim to derive semi-empirical constraints at $z\sim 0.37$ by combining literature results on the $M_\star$ function from optical surveys with recent findings on the $M_{\rm HI}-M_\star$ scaling relation derived via spectral stacking analysis applied to 21-cm line interferometric data from the MIGHTEE and CHILES surveys, conducted with the MeerKAT and VLA radio telescopes, respectively. We draw synthetic $M_\star$ samples directly from the publicly-available results underlying the analysis of the COSMOS2020 galaxy photometric sample. Afterwards, we convert $M_\star$ into $M_{\rm HI}$ using analytical fitting functions to the data points from HI stacking. We then fit a Schechter function to the median HIMF from all the samples via MCMC. We finally derive the posterior distribution for $\Omega_{\rm HI}$ by integrating the models for the HIMF built from the posteriors samples of the Schechter parameters. We find a deviation of the HIMF at $z\sim 0.37$ from the results at $z\sim 0$ from the ALFALFA survey and at $z\sim 1$ from uGMRT data. Our results for $\Omega_{\rm HI}$ are in broad agreement with other literature results, and follow the overall trend on $\Omega_{\rm HI}$ as a function of redshift. The derived value $\Omega_{\rm HI}=\left(7.02^{+0.59}_{-0.52}\right)\times10^{-4}$ at $z\sim 0.37$ from the combined analysis deviates at $\sim 2.9\sigma$ from the ALFALFA result at $z\sim 0$. Our findings about the HIMF and $\Omega_{\rm HI}$ differ from previous literature results at $z\sim0$ and $z\sim1$, although we are unable to confirm at this stage whether these differences are due to cosmic evolution consistent with a smooth transition of the HI content of galaxies over the last 8 Gyr or due to selection biases and systematics.

astro-ph.GA↗

arXiv2025

A PAH deficit in the starburst core of a distant spiral galaxy

We present high-resolution and spatially-matched observations with JWST and ALMA of a starburst galaxy (PACS-830) at $z=1.46$. The NIRCam observations mainly trace the stellar light while the CO ($J$=5--4) observations map the dense molecular gas at kpc scales. Both datasets reveal the morphology to be that of a gas/dust rich bulge with two extending arms, together resembling a grand-design spiral galaxy. The more pronounced arm contributes 21 $\pm$ 6\% of the total CO emission. These results demonstrate that starburst activity at high redshift can be triggered, without undergoing a highly disruptive major merger. We assess the strength and distribution of star formation using two tracers: (1) Polycyclic Aromatic Hydrocarbons (PAHs) emission detected at $8~\mu$m ($L_8$) with a MIRI/F1800W image, and (2) $L_\mathrm{IR}$, inferred from the CO ($J$=5--4) map. The spatial profiles of the $L_\mathrm{IR}$ and $L_8$ are dissimilar, thus leading to a significant deficit of mid-IR ($L_8$) emission in the nucleus. We hypothesize that this is due to the destruction of PAH molecules by the intense ionizing radiation field or decreased emission in the photodissociation region, as seen in nearby star-forming regions and consistent with the galaxy-wide properties of distant starbursts. This study reveals spatial variations in the $L_8$ to $L_\mathrm{IR}$ ratio for the first time at $z>1$, in agreement with expectations from theory. Our analysis underscores the pivotal role of joint high-resolution observations with JWST and ALMA in discerning the different phases of the interstellar medium (ISM) and revealing internal physics in galaxy substructures.

astro-ph.GA↗

arXiv2025

CEERS: Forging the First Dust Grains in the Universe? A Population of Galaxies with spectroscopically-derived Extremely Low Dust Attenuation (GELDA) at 4.0<z<11.4

We investigate the coevolution of metals and dust in 173 galaxies at $4.0 8.8$ (83.3%) than at $z<8.8$ (26.3%) suggesting they dominate the early Universe. Assuming a prior FIR dust spectrum (from ALPINE), we examine dust-stellar mass trends. The $M_{dust}$ vs. $M_{star}$ diagram shows upper and lower sequences linked by possible transitional galaxies. A transition at $M_{star}=10^8.5 M_\odot$ ($Z_{crit}=12+\log_{10}(O/H)=7.60$ or $Z/Z_\odot=0.1$) may mark the shift from stellar dust production to ISM grain growth, in agreement with theoretical predictions. Our full sample has a high mean gas fraction ($f_{gas}>0.9$), indicating retained gas across all galaxies. Their small sizes and large gas masses imply high gas surface densities but relatively low star formation efficiency. High-redshift GELDAs may naturally explain the observed excess of bright galaxies at $z>9$ compared to theoretical expectations.

astro-ph.GA↗