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Widespread, high altitude, diffuse ionized gas with scale heights of around a kiloparsec is observed in the Milky Way and other star-forming galaxies. Numerical radiation-magnetohydrodynamic simulations of a supernova-driven turbulent interstellar medium show that gas can be driven to high altitudes above the galactic mid-plane, but the degree of ionization is often less than inferred from observations. For computational expediency, ionizing radiation from massive stars is often included as a post-processing step assuming ionization equilibrium. We extend our simulations of an Milky Way-like interstellar medium to include the combined effect of supernovae and photoionization feedback from mid-plane OB stars and a population of hot evolved low mass stars. The diffuse ionized gas has densities below 0.1 |${\rm \,cm^{-3}}$|⁠ , so recombination time-scales can exceed millions of years. Our simulations now follow the time-dependent ionization and recombination of low density gas. The long recombination time-scales result in diffuse ionized gas that persists at large altitudes long after the deaths of massive stars that produce the vast majority of the ionized gas. The diffuse ionized gas does not exhibit the large variability inherent in simulations that adopt ionization equilibrium. The vertical distribution of neutral and ionized gas is close to what is observed in the Milky Way. The volume filling factor of ionized gas increases with altitude resulting in the scale height of free electrons being larger than that inferred from H  |$\alpha$| emission, thus reconciling the observations of ionized gas made in H  |$\alpha$| and from pulsar dispersion measurements. [ABSTRACT FROM AUTHOR]

We explore the effect of ionizing ultraviolet background (UVB) on the redshift space clustering of low- z (z ≤ 0.5) O  vi absorbers using the Sherwood simulations incorporating 'WIND' (i.e. outflows driven by stellar feedback)-only and 'WIND + AGN (active galactic nucleus)' feedback. These simulations show positive clustering signals up to a scale of 3 Mpc. We find that the effect of feedback is restricted to small scales (i.e. ≤2 Mpc or ≈200 km s−1 at z ∼ 0.3) and 'WIND'-only simulations produce a stronger clustering signal compared to simulations incorporating 'WIND + AGN' feedback. How the clustering signal is affected by the assumed UVB depends on the feedback processes assumed. For the simulations considered here, the effect of the UVB is confined to even smaller scales (i.e. <1 Mpc or ≈100 km s−1 at z ∼ 0.3). These scales are also affected by exclusion caused by line blending. Therefore, our study suggests that clustering at intermediate scales (i.e. 1–2 Mpc for simulations considered here) together with the observed column density distribution can be used to constrain the effect of feedback in simulations. [ABSTRACT FROM AUTHOR]

The attenuation of Lyα photons by neutral hydrogen in the intergalactic medium (IGM) at z ≳ 5 continues to be a powerful probe for studying the epoch of reionization. Given a framework to estimate the intrinsic (true) Lyα emission of high- z sources, one can infer the ionization state of the IGM during reionization. In this work, we use the enlarged XQR-30 sample of 42 high-resolution and high signal-to-noise quasar spectra between |$5.8\lesssim \, z\lesssim \, 6.6$| obtained with VLT/X-shooter to place constraints on the IGM neutral fraction. This is achieved using our existing Bayesian QSO reconstruction framework which accounts for uncertainties such as the: (i) posterior distribution of predicted intrinsic Lyα emission profiles (obtained via covariance matrix reconstruction of the Lyα and N  v emission lines from unattenuated high-ionization emission line profiles; C  iv , Si  iv   + O  iv ], and C  iii ]) and (ii) distribution of ionized regions within the IGM using synthetic damping wing profiles drawn from a 1.63 Gpc3 reionization simulation. Following careful quality control, we used 23 of the 42 available QSOs to obtain constraints/limits on the IGM neutral fraction during the tail-end of reionization. Our median and 68th percentile constraints on the IGM neutral fraction are: |$0.20\substack{+0.14 -0.12}$| and |$0.29\substack{+0.14 -0.13}$| at z  = 6.15 and 6.35. Further, we also report 68th percentile upper limits of |$\bar{x}_{\mathrm{H\, {\small I}}{}} \lt 0.21$|⁠ , 0.20, 0.21, and 0.18 at z  = 5.8, 5.95, 6.05, and 6.55. These results imply reionization is still ongoing at |$5.8\lesssim \, z\lesssim \, 6.55$|⁠ , consistent with previous results from XQR-30 (dark fraction and Lyα forest) along with other observational probes considered in the literature. [ABSTRACT FROM AUTHOR]

The early stages of the epoch of reionization, probed by the 21 cm line, are sensitive to the detailed properties and formation histories of the first galaxies. We use 21cmfast and a simple, self-consistent galaxy model to examine the redshift evolution of the large-scale cross-power spectrum between the 21 cm field and line-emitting galaxies. A key transition in redshift occurs when the 21 cm field shifts from being positively correlated with the galaxy distribution to being negatively correlated. Importantly, this transition redshift is insensitive to the properties of the galaxy tracers but depends sensitively on the thermal and ionization histories traced through the 21 cm field. Specifically, we show that the transition occurs when both ionization fluctuations dominate over 21 cm spin temperature fluctuations and when the average spin temperature exceeds the temperature of the cosmic microwave background. We illustrate this with three different 21 cm models which have largely the same neutral fraction evolution but different heating histories. We find that the transition redshift has a scale dependence, and that this can help disentangle the relative importance of heating and ionization fluctuations. The best prospects for constraining the transition redshift occur in scenarios with late X-ray heating, where the transition occurs at redshifts as low as z ∼ 6–8. In our models, this requires high-redshift galaxy surveys with sensitivities of |$\sim 10^{-18}~\rm erg\,s^{-1}\,cm^{-2}$| for optical lines and |$\sim 10^{-19}~\rm erg\,s^{-1}\,cm^{-2}$| for far-infrared lines. Future measurements of the transition redshift can help discriminate between 21 cm models and will benefit from reduced systematics. [ABSTRACT FROM AUTHOR]

Primordial neutral atomic gas, mostly composed of hydrogen, is the raw material for star formation in galaxies. However, there are few direct constraints on the amount of neutral atomic hydrogen (H I) in galaxies at early cosmic times. We analyzed James Webb Space Telescope (JWST) near-infrared spectroscopy of distant galaxies, at redshifts ≳8. From a sample of 12 galaxies, we identified three that show strong damped Lyman-a absorption due to H I in their local surroundings. The galaxies are located at spectroscopic redshifts of 8.8, 10.2, and 11.4, corresponding to 400 to 600 million years after the Big Bang. They have H I column densities ≳1022 cm−2, which is an order of magnitude higher than expected for a fully neutral intergalactic medium, and constitute a gas-rich population of young star-forming galaxies. [ABSTRACT FROM AUTHOR]

Electron densities in different locations of our galaxy are obtained in pulsar astronomy by dividing the dispersion measure (DM) by the distance of the pulsar to Earth. The properties of the interstellar plasma are related to its heating by cosmic rays. Following the present analysis, DM's measurements are obtained with different properties of the corresponding plasmas at different temperatures. (1) For relatively low temperatures (around and below 10,000 (K)), the state of molecular, atomic and ionized hydrogen is analyzed by the interstellar medium model with partially ionized plasma. In this region, various spectroscopic effects are obtained. (2) For temperatures above this limit, the interstellar gas is found to be a completely ionized medium, and this plasma is defined as warm ionized medium (WIM) plasma. We show in the first part of the paper that this plasma is transparent, as obtained from the solution of Saha's equation. The index of refraction of the WIM plasma is real, but the plasma can be observed by dispersion measurements. (3) For very high temperatures (around 1 million (K)), the plasma is defined as hot ionized medium, where X-rays are obtained. We concentrate in the present work on the analysis of WIM plasma. We calculate the mass densities of this plasma and compare it with dark matter mass densities, which are found to be larger. But some factors which may reduce this difference are discussed. [ABSTRACT FROM AUTHOR]

We report the detection of the ordered alignment between the magnetic field and kpc-scale bubbles in the nearby spiral galaxy, NGC 628. Applying the Velocity Gradient Technique on CO spectroscopic data from the ALMA-PHANGS, the magnetic field of NGC 628 is measured at the scale of 191 pc (∼4″). The large-scale magnetic field is oriented parallel to the spiral arms and curves around the galactic bubble structures in the mid-infrared emission observed by the James Webb Space Telescope. A total of 21 bubble structures have been identified at the edges of spiral arms with scales over 300 pc, which includes two kpc-scale structures. These bubbles are caused by supernova remnants and prolonged star formation and are similar to the outflow chimneys found in neutral hydrogen in galactic disks. At the edge of the bubbles, the shocks traced by the O iii emission present a curved magnetic field that parallels the bubble's shell. The magnetic field follows the bubble expansion and binds the gas in the shell to trigger further star formation. By analyzing the larger sample of 1694 bubbles, we found a distinct radial-size distribution of bubbles in NGC 628 indicating the star formation history in the galaxy. [ABSTRACT FROM AUTHOR]

The velocity offset of Ly α emission from a galaxy's systemic redshift is an excellent tracer of conditions that enable the escape of Ly α photons from the galaxy, and potentially the all-important hydrogen ionizing Lyman continuum photons. However at z ≥ 6, Ly α is often heavily attenuated by the neutral intergalactic medium. Here we investigate the utility of C  iii ] λλ1907, 1909 emission, usually the brightest ultraviolet (UV) line after Ly α, as a proxy estimating the Ly α velocity offset (Δ v Ly α). To do so, we use analogues of reionization era galaxies based upon 52 star-forming galaxies with robust C  iii ] detections drawn from the VANDELS survey. Our sample spans a broad UV magnitude range of −18.5 < M UV < −22.0, with a sample average value of EW(C  iii ]) = 5.3 Å. We find a slight increase of EW(C  iii ]) with increasing EW(Ly α), but find a large range of EW(C  iii ]) ∼ 1–13 Å particularly at EW(Ly α) < 10 Å. Using the C  iii ] line peak as the systemic redshift, we calculate Δ v Ly α and recover the previously reported trend of decreasing Δ v Ly α with increasing EW(Ly α). Interestingly, we find an anticorrelation between Δ v Ly α and EW(C  iii ]), which also displays a dependence on the UV absolute magnitude. We derive a multivariate fit to obtain Δ v Ly α using both EW(C  iii ]) and M UV, finding that Δ v Ly α is more strongly dependent on EW(C  iii ]), with a weaker but non-negligible dependence on M UV. We find that for a fixed EW(C  iii ]), UV-bright Ly α emitting galaxies show smaller values of Δ v Ly α,which suggests that such galaxies may be undergoing more bursty star-formation compared to the UV-fainter ones, akin to a population of extremely UV-bright galaxies identified at z > 10. [ABSTRACT FROM AUTHOR]

Cyanoketene is a fundamental molecule that is actively being searched for in the interstellar medium. Its deprotonated form (cyanoketenate) is a heterocumulene that is isoelectronic to carbon suboxide whose structure has been the subject of debate. However, the investigation of cyanoketene and its derivatives is hampered by the lack of practical synthetic routes to these compounds. We report the first synthesis of the cyanoketenate anion in [K(18‐crown‐6)][NCCCO] (1) as a stable molecule on a multigram scale in excellent yields (>90 %). The structure of this molecule is probed crystallographically and computationally. We also explore the protonation of 1, and its reaction with triphenylsilylchloride and carbon dioxide. In all cases, anionic dimers are formed. The cyanoketene could be synthesized and crystallographically characterized when stabilized by a N‐heterocyclic carbene. The cyanoketenate is a very useful unsaturated building block containing N, C and O atoms that can now be explored with relative ease and will undoubtedly unlock more interesting reactivity. [ABSTRACT FROM AUTHOR]

The enormous increase in mid-IR sensitivity and spatial and spectral resolution provided by the JWST spectrographs enables, for the first time, detailed extragalactic studies of molecular vibrational bands. This opens an entirely new window for the study of the molecular interstellar medium in luminous infrared galaxies (LIRGs). We present a detailed analysis of rovibrational bands of gas-phase CO, H2O, C2H2, and HCN toward the heavily obscured eastern nucleus of the LIRG VV 114, as observed by NIRSpec and the medium resolution spectrograph on the Mid-InfraRed Instrument (MIRI MRS). Spectra extracted from apertures of 130 pc in radius show a clear dichotomy between the obscured active galactic nucleus (AGN) and two intense starburst regions. We detect the 2.3 μ m CO bandheads, characteristic of cool stellar atmospheres, in the star-forming regions, but not toward the AGN. Surprisingly, at 4.7 μ m, we find highly excited CO (T ex ≈ 700–800 K out to at least rotational level J = 27) toward the star-forming regions, but only cooler gas (T ex ≈ 200 K) toward the AGN. We conclude that only mid-infrared pumping through the rovibrational lines can account for the equilibrium conditions found for CO and H2O in the deeply embedded starbursts. Here, the CO bands probe regions with an intense local radiation field inside dusty young massive star clusters or near the most massive young stars. The lack of high-excitation molecular gas toward the AGN is attributed to geometric dilution of the intense radiation from the bright point source. An overview of the relevant excitation and radiative transfer physics is provided in an appendix. [ABSTRACT FROM AUTHOR]

The large-scale environment of the cosmic web is believed to impact galaxy evolution, but there is still no consensus regarding the mechanisms. We use a semi-analytic model (SAM) galaxy catalog to study the star formation and dust content of local galaxies in different cosmic environments of the cosmic web—namely voids, filaments, walls, and nodes. We find a strong impact of the environment only for galaxies with M stars ≲ 1010.8 M ⊙: the less dense the environment, the larger the star formation rate and dust content at fixed stellar mass. This is attributed to the fact that galaxies in less dense environments typically feature younger stellar populations, a slower evolution of their stellar mass, and delayed star formation compared to galaxies in denser environments. As for galaxies with M stars ≳ 1010.8 M ⊙, the differences among environments are milder, due to the disk-instability-driven supermassive black hole (SMBH) growth implemented in the SAM, which makes SMBH growth, and thus galaxy quenching, environment-insensitive. We qualitatively test our predictions against observations by identifying environments in Sloan Digital Sky Survey Data Release 16 using dust masses derived from the GAMA survey. The agreement is encouraging, particularly at log M stars / M ⊙ ≳ 10.5 – 11 , where the specific star formation rates and dust masses appear quite environment-insensitive. This result confirms the importance of in situ growth channels of SMBHs. [ABSTRACT FROM AUTHOR]

The CO-dark molecular gas (DMG), which refers to the molecular gas not traced by CO emission, is crucial for the evolution of the interstellar medium (ISM). While the gas properties of DMG have been widely explored in the Solar neighborhood, whether or not they are similar in the outer disk regions of the Milky Way is still not well understood. In this Letter, we confirm the existence of DMG toward a cold H I arc structure at 13 kpc away from the Galactic center with both OH emission and H I narrow self-absorption (HINSA). This is the first detection of HINSA in the outer disk region, in which the HINSA fraction (NHINSA/NH2 = 0.022 ± 0.011) is an order of magnitude higher than the average value observed in nearby evolved dark clouds, but is consistent with that of the early evolutionary stage of dark clouds. The inferred H2 column density from both extinction and OH emission (NH2 ≈ 1020 cm−2) is an order of magnitude higher than previously estimated. Although the ISM environmental parameters are expected to be different between the outer Galactic disk regions and the Solar neighborhood, we find that the visual extinction (AV = 0.19 ± 0.03 mag), H2-gas density (nH2 = 91 ± 46 cm−3), and molecular fraction (58% ± 28%) of the DMG are rather similar to those of nearby diffuse molecular clouds. The existence of DMG associated with the expanding H I supershell supports a scenario where the expansion of supershells may trigger the formation of molecular clouds within a crossing timescale of the shock wave (∼106 yr). [ABSTRACT FROM AUTHOR]

We report the detection of extended (> 0.5–1 kpc) high-ionization [Mg IV] 4.487 μm (80 eV) emission in four local luminous infrared galaxies observed with JWST/NIRSpec. Excluding the nucleus and outflow of the Type 1 active galactic nucleus (AGN) in the sample, we find that the [Mg IV] luminosity is well correlated with that of H recombination lines, which mainly trace star-forming clumps in these objects, and that the [Ar VI] 4.530 μm (75 eV), usually seen in AGN, is undetected. On 100–400 pc scales, the [Mg IV] line profiles are broader (σ([Mg IV]) = 90 ± 25 km s−1) and shifted (Δv up to ±50 km s−1) compared to those of the H recombination lines and lower ionization transitions (e.g., σ(Hu-12) = 57 ± 15 km s−1). The [Mg IV] kinematics follow the large-scale rotating velocity field of these galaxies, and the broad [Mg IV] profiles are compatible with the broad wings detected in the H recombination lines. Based on these observational results, extended highly ionized gas more turbulent than the ambient interstellar medium, possibly a result of ionizing shocks associated with star formation, is the most likely origin of the [Mg IV] emission. We also computed new grids of photoionization and shock models to investigate where the [Mg IV] line originates. Shocks with velocities of 100–130 km s−1 reproduce the observed line ratios and the [Mg IV] luminosity agrees with that expected from the mechanical energy released by supernove (SNe) in these regions. Therefore, these models support shocks induced by SNe as the origin of the [Mg IV] line. Future studies on the stellar feedback from SNe will benefit from the [Mg IV] line that is little affected by obscuration and, in the absence of an AGN, can only be produced by shocks due to its high ionization-potential. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Impact of nonconvergence and various approximations of the partition function on the molecular column densities in the interstellar medium." The full text of the article is not available in HTML format. The authors acknowledge the contributions of Dr. Edgar Mendoza and the funding received from the European Union's Horizon 2020 research and innovation program. The authors of the article are M. Carvajal, C. Favre, I. Kleiner, C. Ceccarelli, E. A. Bergin, and D. Fedele. [Extracted from the article]

Context. Nitrogen fractionation is a powerful tracer of the chemical evolution during star and planet formation. It requires robust determinations of the nitrogen fractionation across different evolutionary stages. Aims. We aim to determine the 14N/15N and 12C/13C ratios for HCN in six starless and prestellar cores and to compare the results between the direct method using radiative transfer modeling and the indirect double isotope method, assuming a fixed 12C/13C ratio. Methods. We present IRAM observations of the HCN 1–0, HCN 3–2, HC15N 1–0 and H13CN 1–0 transitions toward six embedded cores. The 14N/15N ratio was derived using both the indirect double isotope method and directly through non-local thermodynamic equilibrium (NLTE) 1D radiative transfer modeling of the HCN emission. The latter also provides the 12C/13C ratio, which we compared to the local interstellar value. Results. The derived 14N/15N ratios using the indirect method are generally in the range of 300-550. This result could suggest an evolutionary trend in the nitrogen fractionation of HCN between starless cores and later stages of the star formation process. However, the direct method reveals lower fractionation ratios of around ~250, mainly resulting from a lower 12C/13C ratio in the range ~20–40, as compared to the local interstellar medium value of 68. Conclusions. This study reveals a significant difference between the nitrogen fractionation ratio in HCN derived using direct and indirect methods. This can influence the interpretation of the chemical evolution and reveal the pitfalls of the indirect double isotope method for fractionation studies. However, the direct method is challenging, as it requires well-constrained source models to produce accurate results. No trend in the nitrogen fractionation of HCN between earlier and later stages of the star formation process is evident when the results of the direct method are considered. [ABSTRACT FROM AUTHOR]

Aromatic infrared bands (AIBs) are a set of broad emission bands at 3.3, 6.2, 7.7, 8.6, 11.2, and 12.7 μm, seen in the infrared spectra of most galaxies. With the James Webb Space Telescope (JWST), the 3.3 μm AIB can in principle be detected up to a redshift of ~7. Relating the evolution of the 3.3 μm AIB to local physical properties of the interstellar medium (ISM) is thus of paramount importance. By applying a dedicated machine learning algorithm to JWST NIRSpec observations of the Orion Bar photodissociation region obtained as part of the PDRs4All Early Release Science (ERS) program, we extracted two template spectra capturing the evolution of the AIB-related emission in the 3.2–3.6 μm range, which includes the AIB at 3.3 μm and its main satellite band at 3.4 μm. In the Orion Bar, we analyzed the spatial distribution of the templates and their relationship with the ro-vibrational H2 line at 2.12 μm, the pure rotational line of H2 at 4.69 μm and the Pfund δ line at 3.29 μm. We find that one template (AIBIrrad) traces regions of neutral atomic gas with strong far-UV fields, while the other template (AIBShielded) corresponds to shielded regions with lower FUV fields and a higher molecular gas fraction. We then show that these two templates can be used to fit the NIRSpec AIB-related spectra of nearby galaxies. The relative weight of the two templates (AIBIrrad/Shielded) is a tracer of the radiative feedback from massive stars on the ISM. We derive an estimate of AIBIrrad/Shielded in a z = 4.22 lensed galaxy and find that it has a lower value than for local galaxies. This pilot study illustrates how a detailed analysis of AIB emission in nearby regions can be used to probe the physical conditions of the extragalactic ISM. [ABSTRACT FROM AUTHOR]

Context. The chemical evolution of distant galaxies cannot be assessed from observations of individual stars, in contrast to the case of nearby galaxies. On the other hand, the study of the interstellar medium (ISM) offers an alternative way to reveal important properties of the chemical evolution of distant galaxies. The chemical enrichment of the ISM is produced by all the previous generations of stars and it is possible to precisely determine the metal abundances in the neutral ISM in galaxies. The chemical abundance patterns in the neutral ISM are determined by the gas metallicity, presence of dust (the depletion of metals into dust grains), and possible deviations due to specific nucleosynthesis, for example, α-element enhancements. Aims. We aim to derive the metallicities, dust depletion, and α-element enhancements in the neutral ISM of gas-rich mostly-metal-poor distant galaxies (Damped Lyman-α absorbers, DLAs). Furthermore, we aim to constrain the distribution of α-element enhancements with metallicity in these galaxies. Methods. We collected a literature sample of column density measurements of O, Mg, Si, S, Ti, Cr, Fe, Ni, Zn, P, and Mn in the neutral ISM of DLAs at redshifts of 0.60 < z < 3.40. We used this sample to define a golden sample of DLAs with constrained observations of Ti and at least one other α-element. By studying the abundance patterns, we determined the amount of dust depletion, solely based on the observed relative abundances of the α-elements. We then used the abundances of Fe-peak elements to determine the overall metallicity of each system, after correcting for dust depletion. In addition, we studied the deviations from the basic (linear) abundance patterns. We divided our sample into two groups of galaxies based on the widths of their absorption lines (Δv90 above or below 100 km s−1), which may be considered as a proxy for their dynamical mass. We characterised the distribution of the α-element enhancements as a function of metallicity for the galaxy population as a whole, by fitting a piecewise function (plateau, decline, plateau) to the data. Results. We observed systematic deviations from the basic abundance patterns for O, Mg, Si, S, Ti, and Mn, which we interpreted as α-element enhancements and a Mn underabundance. The distribution of the α-element enhancements with metallicity is different in the high-Δv90 and low-Δv90 groups of galaxies. We constrained the metallicity of the α-element knee for the high-Δv90 and low-Δv90 groups of galaxies to be −1.02±0.15 dex and −1.84±0.11 dex, respectively. The average α-element enhancement at the high-plateau is [α/Fe]=0.38±0.07 dex. On the other hand, Mn shows an underabundance in all DLAs in the golden sample of −0.36±0.07 dex, on average. Conclusions. We have constrained, for the first time, the distribution of the α-element enhancement with metallicity in the neutral ISM in distant galaxies. Less massive galaxies show an α-element knee at lower metallicities than more massive galaxies. This can be explained by a lower star formation rate in less massive galaxies. If this collective behaviour can be interpreted in the same way as it is for individual systems, this would suggest that more massive and metal-rich systems evolve to higher metallicities before the contribution of SN-Ia to [α/Fe] levels out that of core-collapse SNe. This finding may plausibly be supported by different SFRs in galaxies of different masses. Overall, our results offer important clues to the study of chemical evolution in distant galaxies. [ABSTRACT FROM AUTHOR]

The X-ray luminosity function (XLF) of active galactic nuclei (AGN) offers a robust tool to study the evolution and the growth of the supermassive black-hole population over cosmic time. Owing to the limited area probed by X-ray surveys, optical surveys are routinely used to probe the accretion in the high-redshift Universe z ≥ 3. However, optical surveys may be incomplete because they are strongly affected by dust redenning. In this work we derive the XLF and its evolution at high redshifts (z ≥ 3) using a large sample of AGN selected in different fields with various areas and depths covering a wide range of luminosities. Additionally, we put the tightest yet constraints on the absorption function in this redshift regime. In particular, we used more than 600 soft X-ray selected (0.5 − 2 keV) high-z sources in the Chandra deep fields, the Chandra COSMOS Legacy survey, and the XMM-XXL northern field. We derived the X-ray spectral properties for all sources via spectral fitting, using a consistent technique and model. To model the parametric form of the XLF and the absorption function, we used a Bayesian methodology, allowing us to correctly propagate the uncertainties for the observed X-ray properties of our sources and also the absorption effects. The evolution of XLF is in agreement with a pure density evolution model similar to what is witnessed at optical wavelengths, although a luminosity-dependent density evolution model cannot be securely ruled out. A large fraction (∼60%) of our sources are absorbed by column densities of NH ≥ 1023 cm−2, while ∼17% of the sources are Compton-Thick. Our results favour a scenario where both the interstellar medium of the host and the AGN torus contribute to the obscuration. The derived black hole accretion rate density is roughly in agreement with the large-scale cosmological hydrodynamical simulations, if one takes into account the results that the X-ray AGN are hosted by massive galaxies, while it differs from that derived using JWST data. The latter could be due to the differences in the AGN and host-galaxy properties. [ABSTRACT FROM AUTHOR]

Context. The infrared (IR) range is extremely useful in the context of chemical abundance studies of the gas-phase interstellar medium (ISM) due to the large variety of ionic species traced in this regime, the negligible effects from dust attenuation or temperature stratification, and the amount of data that has been and will be released in the coming years. Aims. Taking advantage of available IR emission lines, we analysed the chemical content of the gas-phase ISM in a sample of 131 star-forming galaxies (SFGs) and 73 active galactic nuclei (AGNs). In particular, we derived the chemical content via their total oxygen abundance in combination with nitrogen and sulphur abundances, and with the ionisation parameter. Methods. We used a new version of the code HII-CHI-MISTRY-IR v3.1, which allowed us to estimate log(N/O), 12+log(O/H), log(U) and, for the first time, 12+log(S/H) from IR emission lines, which can be applied to both SFGs and AGNs. We tested whether the estimates from this new version, which only considers sulphur lines for the derivation of sulphur abundances, are compatible with previous studies. Results. While most of the SFGs and AGNs show solar log(N/O) abundances, we find a large spread in the log(S/O) relative abundances. Specifically, we find extremely low log(S/O) values (1/10 solar) in some SFGs and AGNs with solar-like oxygen abundances. This result warns against the use of optical and IR sulphur emission lines to estimate oxygen abundances when no prior estimation of log(S/O) is provided. [ABSTRACT FROM AUTHOR]

Context. Hadronic interactions between cosmic rays (CRs) and interstellar gas have been probed in γ rays across the Galaxy. A fairly uniform CR distribution is observed up to a few hundred parsecs from the Sun, except in the Eridu cloud, which shows an unexplained 30–50% deficit in GeV to TeV CR flux. Aims. To explore the origin of this deficit, we studied the Reticulum cloud, which shares notable traits with Eridu: a comparable distance in the low-density region of the Local Valley and a filamentary structure of atomic hydrogen extending along a bundle of ordered magnetic-field lines that are steeply inclined to the Galactic plane. Methods. We measured the γ-ray emissivity per gas nucleon in the Reticulum cloud in the 0.16–63 GeV energy band using 14 years of Fermi-LAT data. We also derived interstellar properties that are important for CR propagation in both the Eridu and Reticulum clouds, at the same parsec scale. Results. The γ-ray emissivity in the Reticulum cloud is fully consistent with the average spectrum measured in the solar neighbourhood, but this emissivity, and therefore the CR flux, is 1.57 ± 0.09 times larger than in Eridu across the whole energy band. The difference cannot be attributed to uncertainties in gas mass. Nevertheless, we find that the two clouds are similar in many respects: both have magnetic-field strengths of a few micro-Gauss in the plane of the sky; both are in approximate equilibrium between magnetic and thermal pressures; they have similar turbulent velocities and sonic Mach numbers; and both show magnetic-field regularity with a dispersion in orientation lower than 10°–15° over large zones. The gas in Reticulum is colder and denser than in Eridu, but we find similar parallel diffusion coefficients around a few times 1028 cm2 s−1 in both clouds if CRs above 1 GV in rigidity diffuse on resonant, self-excited Alfvén waves that are damped by ion-neutral interactions. Conclusions. The loss of CRs in Eridu remains unexplained, but these two clouds provide important test cases to further study how magnetic turbulence, line tangling, and ion-neutral damping regulate CR diffusion in the dominant gas phase of the interstellar medium. [ABSTRACT FROM AUTHOR]

Context. JWST has taken the sharpest and most sensitive infrared (IR) spectral imaging observations ever of the Orion Bar photodis-sociation region (PDR), which is part of the nearest massive star-forming region the Orion Nebula, and often considered to be the 'prototypical' strongly illuminated PDR. Aims. We investigate the impact of radiative feedback from massive stars on their natal cloud and focus on the transition from the H II region to the atomic PDR – crossing the ionisation front (IF) –, and the subsequent transition to the molecular PDR – crossing the dissociation front (DF). Given the prevalence of PDRs in the interstellar medium and their dominant contribution to IR radiation, understanding the response of the PDR gas to far-ultraviolet (FUV) photons and the associated physical and chemical processes is fundamental to our understanding of star and planet formation and for the interpretation of any unresolved PDR as seen by JWST. Methods. We used high-resolution near-IR integral field spectroscopic data from NIRSpec on JWST to observe the Orion Bar PDR as part of the PDRs4All JWST Early Release Science programme. We constructed a 3″ × 25″' spatio-spectral mosaic covering 0.97– 5.27 μm at a spectral resolution R of ~2700 and an angular resolution of 0.075″–0.173″. To study the properties of key regions captured in this mosaic, we extracted five template spectra in apertures centred on the three H2 dissociation fronts, the atomic PDR, and the H II region. This wealth of detailed spatial-spectral information was analysed in terms of variations in the physical conditions-incident UV field, density, and temperature – of the PDR gas. Results. The NIRSpec data reveal a forest of lines including, but not limited to, He I, H I , and C I recombination lines; ionic lines (e.g. Fe III and Fe II); O I and N I fluorescence lines; aromatic infrared bands (AIBs, including aromatic CH, aliphatic CH, and their CD counterparts); pure rotational and ro-vibrational lines from H2; and ro-vibrational lines from HD, CO, and CH+, with most of them having been detected for the first time towards a PDR. Their spatial distribution resolves the H and He ionisation structure in the Huygens region, gives insight into the geometry of the Bar, and confirms the large-scale stratification of PDRs. In addition, we observed numerous smaller-scale structures whose typical size decreases with distance from θ1 Ori C and IR lines from C I , if solely arising from radiative recombination and cascade, reveal very high gas temperatures (a few 1000 K) consistent with the hot irradiated surface of small-scale dense clumps inside the PDR. The morphology of the Bar, in particular that of the H2 lines, reveals multiple prominent filaments that exhibit different characteristics. This leaves the impression of a 'terraced' transition from the predominantly atomic surface region to the CO-rich molecular zone deeper in. We attribute the different characteristics of the H2 filaments to their varying depth into the PDR and, in some cases, not reaching the C+/C/CO transition. These observations thus reveal what local conditions are required to drive the physical and chemical processes needed to explain the different characteristics of the DFs and the photochemical evolution of the AIB carriers. Conclusions. This study showcases the discovery space created by JWST to further our understanding of the impact radiation from young stars has on their natal molecular cloud and proto-planetary disk, which touches on star and planet formation as well as galaxy evolution. [ABSTRACT FROM AUTHOR]

We present the results of a ∼60-h multiband observational campaign with the Atacama Large Millimeter Array targeting a spectroscopically confirmed and lensed sub-L⋆ galaxy at z = 6.07, first identified during the ALMA Lensing Cluster Survey (ALCS). We sampled the dust continuum emission from rest frame 90–370 μm at six different frequencies and set constraining upper limits on the molecular gas line emission and content by targeting the CO (7 − 6) and [C I](3P2−3P1) transitions in two lensed images with μ ≳ 20. Complementing these submillimeter observations with deep optical and near-IR photometry and spectroscopy with JWST, we find this galaxy to form stars at a rate of SFR ∼ 7 M⊙ yr−1, ∼50 − 70% of which is obscured by dust. This is consistent with what one would predict for a M⋆ ∼ 7.5 × 108 M⊙ object by extrapolating the relation between the fraction of the obscured star formation rate and stellar mass at z <  2.5 and with observations of IR-detected objects at 5 <  z <  7. The light-weighted dust temperature of Tdust ∼ 50 K is similar to that of more massive galaxies at similar redshifts, although with large uncertainties and with possible negative gradients. We measure a dust mass of Mdust ∼ 1.5 × 106 M⊙ and, by combining [C I], [C II], and a dynamical estimate, a gas mass of Mgas ∼ 2 × 109 M⊙. Their ratio (δDGR) is in good agreement with predictions from models and empirical relations in the literature. The dust-to-stellar mass fraction of fdust ∼ 0.002 and the young stellar age (100 − 200 Myr) are consistent with efficient dust production via supernovae, as predicted by existing models and simulations of dust evolution. Also, the expected number density of galaxies with Mdust ∼ 106 M⊙ at z = 6 from a subset of these models is in agreement with the observational estimate that we set from the parent ALCS survey. The combination of gravitational lensing and deep multiwavelength observations allowed us to probe luminosity and mass regimes up to two orders of magnitude lower than what has been explored so far for field galaxies at similar redshifts. Our results serve as a benchmark for future observational endeavors of the high-redshift and faint sub-L⋆ galaxy population that might have driven the reionization of the Universe. [ABSTRACT FROM AUTHOR]

Context. Starburst galaxies are undergoing intense episodes of star formation. In these galaxies, gas is ejected into the surrounding environment through winds created by the effect of hot stars and supernova explosions. When interacting with the intergalactic medium, these winds can produce strong shocks capable of accelerating cosmic rays. The radiation from these cosmic rays mainly occurs in radio and gamma rays. The radio halo can be characterized using the scale height, which is an important parameter for understanding cosmic ray acceleration and transport. Aims. We searched for the presence of radio halos in a sample of edge-on starburst galaxies gathered from the MeerKAT 1.28 GHz Atlas of Southern Sources in the IRAS Revised Bright Galaxy Sample. The investigation of how the radio halos relate to the global properties of the galaxies can shed light on the understanding of the halo origin and the underlying cosmic ray population. Methods. We selected a sample of 25 galaxies with inclinations i > 80° from the original sample and modeled their disk and halo contributions. We determined the scale heights and the radio luminosity of the halos when detected. Results. We have detected and characterized 11 radio halos from a sample of 25 edge-on galaxies. Seven of them are reported here for the first time. The average radio scale height is ∼1 kpc. We found that the halo scale heights increase linearly with the radio diameters and this relation does not depend on the star formation rate. All galaxies in our sample follow the radio-infrared relation with a q parameter value of 2.5 ± 0.1. The halo luminosity linearly increases with the infrared luminosity and star formation rate. Conclusions. The dependence of the halo luminosity on the star formation rate and the infrared luminosity supports the hypothesis that the radio halos are the result of synchrotron radiation produced by relativistic electrons and points toward the fact that the star formation activity plays a crucial role in halo creation. The average scale height of 1 kpc implies a dynamical range of 4 Myr, several orders of magnitude greater than the synchrotron losses for electrons of 10 TeV. This suggests that some process must exist to reaccelerate cosmic rays in the halo if gamma-ray emission of a leptonic origin is detected from the halo. According to the relation between the radio and gamma-ray luminosities, we found that NGC 4666 is a potential gamma-ray source for future observations. [ABSTRACT FROM AUTHOR]

Context. Supernovae remnants (SNRs) represent a major source of feedback from stars on the interstellar medium of galaxies. During the latest stage of supernova explosions (which lasts 10–100 kyr), shock waves produced by the initial blast modify the chemistry of gas and dust, inject kinetic energy in the surroundings, and may alter star formation characteristics. Simultaneously, γ-ray emission is generated by the interaction between the ambient medium and cosmic rays, in particular those locally accelerated in the early stages of the explosion. Aims. We aim to estimate the total molecular mass, local density, and total column density of H2 and the temperature structure in a shocked clump interacting with the supernova remnant IC443 located in a region where cosmic rays interact with the interstellar medium. Measuring the mass of the dense and neutral component of the medium is a prerequisite to understanding the chemistry, energetics, and GeV to TeV γ-ray emission. Methods. Assuming that the emission of H2 pure rotational lines is produced by a collection of gas layers with variable temperature, we compared Spitzer/IRS emission maps for the ν = 0–0 S(0) to S(7) lines with a thermal admixture model. Our description is based on a power-law distribution of thermalized components with temperatures varying between Tmin = 25 K and Tmax = 1500 K. Results. Our thermal admixture model allows the level populations of H2 to be described by a power-law distribution dN = ΛT−ΓdT, with Γ ~ 2.2−4.7. We measured a total mass MH2 = 220−80+110M⊙ across the Spitzer/IRS field of observations. Conclusions. Our analysis shows that an estimate of the cold molecular gas temperature is paramount to accurately constraining the H2 mass, although the mass remains affected by significant uncertainties due to the assumptions on the gas temperature distribution. [ABSTRACT FROM AUTHOR]

The Epoch of Reionization (EoR) began when galaxies grew in abundance and luminosity, so their escaping Lyman continuum (LyC) radiation started ionizing the surrounding neutral intergalactic medium (IGM). Despite significant recent progress, the nature and role of cosmic reionizers are still unclear: in order to define them, it would be necessary to directly measure their LyC escape fraction (fesc). However, this is impossible during the EoR due to the opacity of the IGM. Consequently, many efforts at low and intermediate redshift have been made to determine measurable indirect indicators in high-redshift galaxies so that their fesc can be predicted. This work presents the analysis of the indirect indicators of 62 spectroscopically confirmed star-forming galaxies at 6 ≤ z ≤ 9 from the Cosmic Evolution Early Release Science (CEERS) survey, combined with 12 sources with public data from other JWST-ERS campaigns. From the NIRCam and NIRSpec observations, we measured their physical and spectroscopic properties. We discovered that on average 6 < z < 9 star-forming galaxies are compact in the rest-frame UV (re ∼ 0.4 kpc), are blue sources (UV-β slope ∼ − 2.17), and have a predicted fesc of about 0.13. A comparison of our results to models and predictions as well as an estimation of the ionizing budget suggests that low-mass galaxies with UV magnitudes fainter than M1500 = −18 that we currently do not characterize with JWST observations probably played a key role in the process of reionization. [ABSTRACT FROM AUTHOR]

Context. High-resolution 3D maps of interstellar dust are critical for probing the underlying physics shaping the structure of the interstellar medium, and for foreground correction of astrophysical observations affected by dust. Aims. We aim to construct a new 3D map of the spatial distribution of interstellar dust extinction out to a distance of 1.25 kpc from the Sun. Methods. We leveraged distance and extinction estimates to 54 million nearby stars derived from the Gaia BP/RP spectra. Using the stellar distance and extinction information, we inferred the spatial distribution of dust extinction. We modeled the logarithmic dust extinction with a Gaussian process in a spherical coordinate system via iterative charted refinement and a correlation kernel inferred in previous work. In total, our posterior has over 661 million degrees of freedom. We probed the posterior distribution using the variational inference method MGVI. Results. Our 3D dust map has an angular resolution of up to 14′ (Nside = 256), and we achieve parsec-scale distance resolution, sampling the dust in 516 logarithmically spaced distance bins spanning 69 pc to 1250 pc. We generated 12 samples from the variational posterior of the 3D dust distribution and release the samples alongside the mean 3D dust map and its corresponding uncertainty. Conclusions. Our map resolves the internal structure of hundreds of molecular clouds in the solar neighborhood and will be broadly useful for studies of star formation, Galactic structure, and young stellar populations. It is available for download in a variety of coordinate systems online and can also be queried via the publicly available dustmaps Python package. [ABSTRACT FROM AUTHOR]

We investigate the incidence and properties of ionised gas outflows in a sample of 52 galaxies with stellar masses between 107M⊙ and 109M⊙ observed with ultra-deep JWST/NIRSpec MSA spectroscopy as part of the JWST Advanced Deep Extragalactic Survey (JADES). The high-spectral resolution (R2700) NIRSpec observations allowed us to identify for the first time the potential signature of outflows in the rest-frame optical nebular lines in low-mass galaxies at z > 4. The incidence fraction of ionised outflows, traced by broad components, is about 25–40%, depending on the intensity of the emission lines. The low incidence fraction might be due to both the sensitivity limit and the fact that outflows are not isotropic, but have a limited opening angle, which only results in detection when this is directed toward our line of sight. Evidence for outflows increases slightly with stellar mass and star formation rate. The median velocity and mass-loading factor (i.e. the ratio of the mass outflow rate and star formation rate) of the outflowing ionised gas are 350 km s−1 and η = 2.0−1.5+1.6, respectively. These are 1.5 and 100 times higher than the typical values observed in local dwarf galaxies. Some of these high-redshift outflows can escape the gravitational potential of the galaxy and dark matter halo and enrich the circumgalactic medium and possibly even the intergalactic medium. Our results indicate that outflows can significantly impact the star formation activity in low-mass galaxies within the first 2 Gyr of the Universe. [ABSTRACT FROM AUTHOR]

The assembly and build-up of neutral atomic hydrogen (H I) in galaxies is one of the most fundamental processes in galaxy formation and evolution. Studying this process directly in the early universe is hindered by the weakness of the hyperfine 21-cm H I line transition, impeding direct detections and measurements of the H I gas masses (MHI). Here we present a new method to infer MHI of high-redshift galaxies using neutral, atomic oxygen as a proxy. Specifically, we derive metallicity-dependent conversion factors relating the far-infrared [O I]-63 μm and [O I]-145 μm emission line luminosities and MHI in star-forming galaxies at z ≈ 2 − 6 using gamma-ray bursts (GRBs) as probes. We calibrate the [O I]-to-H I conversion factor relying on a sample of local galaxies with direct measurements of MHI and [O I]-63 μm and [O I]-145 μm line luminosities in addition to the SIGAME hydrodynamical simulation framework at similar epochs (z ≈ 0). We find that the [O I]63 μm-to-H I and [O I]145 μm-to-H I conversion factors, here denoted β[OI]−63 μm and β[OI]−145 μm, respectively, universally appear to be anti-correlated with the gas-phase metallicity. The GRB measurements further predict a mean ratio of L[OI]−63 μm/L[OI]−145 μm = 1.55 ± 0.12 and reveal generally less excited [C II] over [O I] compared to the local galaxy sample. The z ≈ 0 galaxy sample also shows systematically higher β[OI]−63 μm and β[OI]−145 μm conversion factors than the GRB sample, indicating either suppressed [O I] emission in local galaxies likely due to their lower hydrogen densities or more extended, diffuse H I gas reservoirs traced by the H I 21-cm. Finally, we apply these empirical calibrations to the few detections of [O I]-63 μm and [O I]-145 μm line transitions at z ≈ 2 from the literature and further discuss the applicability of these conversion factors to probe the H I gas content in the dense, star-forming interstellar medium (ISM) of galaxies well into the epoch of reionization. [ABSTRACT FROM AUTHOR]

Context. The presence of cold gas (T ≲ 104 K) in the circumgalactic medium (CGM) of galaxies has been confirmed in observations and in high-resolution simulations, but its origin is still a puzzle. Possible mechanisms are cold accretion from the intergalactic medium (IGM), clumps embedded in outflows and transported from the disk, and gas detaching from the hot CGM phase via thermal instabilities. Aims. In this work we characterize the history of cold CGM gas in order to identify the dominant origin channels at different evolutionary stages of the main galaxy. Methods. To this end, we tracked gas particles in different snapshots of the smoothed particle hydrodynamics (SPH) cosmological zoom-in simulation Eris2k. We performed a backward tracking of cold gas, starting from different redshifts until we could identify one of the followings origins for the particle: cold inflow, ejection from the disk, cooling down in situ, or stripping from a satellite. We also performed a forward tracking of gas in different components of the galaxy (such as the disk and outflows). Results. We find a clear transition between two epochs. For z > 2, most cold gas (up to 80%) in the CGM comes from cold accretion streams as the galaxy is accreting in the cold mode from the IGM. At lower z, gas either cools down in situ after several recycles (with 10–20% of the gas cooling in outflow), or it is ejected directly from the disk (up to 30%). Outflows have a major contribution to the cold CGM gas budget at z < 1, with almost 50% of the hot gas cooling in outflow. Finally, we discuss possible mechanisms for CGM cooling, showing that the thermally unstable gas with tcool/tff < 1 (precipitation-regulated feedback) is abundant up to r ∼ 100 kpc and cooling times are shorter than 50 Myr for densities n > 10−2 cm−3. [ABSTRACT FROM AUTHOR]

We report on a study of 9 nearby primitive galaxies observed by Hubble's COS far-UV spectrograph that can serve as templates of high-z galaxies to be observed by JWST. By "primitive galaxies," we mean galaxies having a low stellar mass, and low gas metallicity, , whether they are local or at high redshift. We find that far-UV spectra of these galaxies show evidence of hard radiation, including X-rays. Following Thuan et al. (2004), we identify these galaxies as massive X-ray binaries containing a massive accreting stellar black hole. We further find that the lower the metallicity, the higher the probability of extremely strong X-radiation. Following Heger et al. (2003), we suggest that the accreting black hold is produced by direct collapse of stars having initial masses greater than 50. The X-radiation produced by black hole disk directly affects the surrounding interstellar medium, and many of these effects are observable in far-UV spectra. [ABSTRACT FROM AUTHOR]

The spatial fluctuations in the tomographic maps of the redshifted 21-cm signal from the Cosmic Dawn (CD) crucially depend on the size and distribution of the regions with gas temperatures larger than the radio background temperature. In this article, we study the morphological characteristics of such emission regions and their absorption counterparts using the shape diagnostic tool surfgen2. Using simulated CD brightness temperature cubes of the 21-cm signal, we find that the emission regions percolate at stages with the filling factor of the emission regions |$\mathrm{FF}_{\rm emi}\gtrsim 0.15$|⁠. Percolation of the absorption regions occurs for |$\mathrm{FF}_{\rm abs}\gtrsim 0.05$|⁠. The largest emission and absorption regions are topologically complex and highly filamentary for most parts of the CD. The number density of these regions as a function of the volume shows the power-law nature with the power-law indexes |$\approx -2$| and |$-1.6$| for the emission and absorption regions, respectively. Overall, the planarity, filamentarity, and genus increase with the increase of the volume of both emission and absorption regions. [ABSTRACT FROM AUTHOR]

We present results of dust continuum and [C  ii ] |$\, 158\, {\rm \mu m}$| emission line observations of a remarkably UV luminous (M UV = −21.6) galaxy at z = 10.603: GN-z11. Using the Northern Extended Millimeter Array (NOEMA), observations have been carried out over multiple observing cycles. We achieved a high sensitivity resulting in a |$\lambda _{\rm rest}=160\, {\rm \mu m}$| continuum |$1\, \sigma$| sensitivity of |$13.0\, \rm {\mu Jy \, beam}^{ -1}$| and a [C  ii ] emission line |$1\, \sigma$| sensitivity of |$31\, \rm {mJy\, beam^{ -1}\, km \, s}^{ -1}$| using |$50\, \rm {km \, s}^{ -1}$| binning with a |$\sim 2\, {\rm arcsec}$| synthesized beam. Neither dust continuum nor [C  ii ] |$\, 158\, {\rm \mu m}$| line emission are detected at the expected frequency of ν[C ii ] |$= 163.791\, \rm {GHz}$| and the sky location of GN-z11. The upper limits show that GN-z11 is neither luminous in L IR nor L [C ii ], with a dust mass |$3\, \sigma$| limit of |${\rm log}\, (M_{\rm dust}/{\rm {\rm M}_{\odot }}) \, \lt\, 6.5-6.9$| and with a [C  ii ] based molecular gas mass |$3\, \sigma$| limit of log (M mol, [C ii ] |$/{\rm {\rm M}_{\odot }}) \, \lt \, 9.3$|⁠. Together with radiative transfer calculations, we also investigated the possible cause of the dust poor nature of the GN-z11 showed by the blue colour in the UV continuum of GN-z11 (βUV = −2.4), and found that ≳3 × deeper observations are crucial to study dust production at very high-redshift. Nevertheless, our observations show the crucial role of deep mm/submm observations of very high-redshift galaxies to constrain multiple phases in the interstellar medium. [ABSTRACT FROM AUTHOR]

The X C O factor is defined as X C O = N (H 2) / W 12 C O . It is useful for estimating cloud mass. However, there is only limited research on how the X C O factor varies within a single cloud. Employing 12 C O (J = 1-0) and 13 C O (J = 1-0) spectral data, we computed an X C O factor of 3.6 × 10 20 cm − 2 (K km s−1)−1 for luminous gas of the N55 region. Our analysis revealed a V-shaped correlation between the X C O factor and H 2 column densities, while the relationship with excitation temperature exhibited obscurity. This suggests that the CO-to- H 2 conversion is not consistent on small scale (∼1 pc). Additionally, we found that star formation activity has little influence on the variability in the X C O factor. [ABSTRACT FROM AUTHOR]

Cosmic rays (CRs) may drive outflows and alter the phase structure of the circumgalactic medium, with potentially important implications on galaxy formation. However, these effects ultimately depend on the dominant mode of transport of CRs within and around galaxies, which remains highly uncertain. To explore potential observable constraints on CR transport, we investigate a set of cosmological fire -2 CR-magnetohydrodynamic simulations of L* galaxies which evolve CRs with transport models motivated by self-confinement (SC) and extrinsic turbulence (ET) paradigms. To first order, the synchrotron properties diverge between SC and ET models due to a CR physics-driven hysteresis. SC models show a higher tendency to undergo 'ejective' feedback events due to a runaway buildup of CR pressure in dense gas due to the behaviour of SC transport scalings at extremal CR energy densities. The corresponding CR wind-driven hysteresis results in brighter, smoother, and more extended synchrotron emission in SC runs relative to ET and constant diffusion runs. The differences in synchrotron arise from different morphology, interstellar medium gas, and B properties, potentially ruling out SC as the dominant mode of CR transport in typical star-forming L* galaxies, and indicating the prospect for non-thermal radio continuum observations to constrain CR transport physics. [ABSTRACT FROM AUTHOR]

Stellar feedback plays a crucial role in regulating baryon cycles of a galactic ecosystem, and may manifest itself in the formation of superbubbles in the interstellar medium. In this work, we used a set of high-resolution simulations to systematically study the properties and evolution of superbubbles in galactic environments. The simulations were based on the SMUGGLE galaxy formation framework using the hydrodynamical moving-mesh code arepo , reaching a spatial resolution of |$\sim 4 \, \rm pc$| and mass resolution of |$\sim 10^3 \, \rm M_{\odot }$|⁠. We identified superbubbles and tracked their time evolution using the parent stellar associations within the bubbles. The X-ray luminosity-size distribution of superbubbles in the fiducial run is largely consistent with the observations of nearby galaxies. The size of superbubbles shows a double-peaked distribution, with the peaks attributed to early feedback (radiative and stellar wind feedback) and supernova feedback. The early feedback tends to suppress the subsequent supernova feedback, and it is strongly influenced by star formation efficiency, which regulates the environmental density. Our results show that the volume filling factor of hot gas (T > 105.5 K) is about |$12~{{\ \rm per\ cent}}$| averaged over a region of 4 kpc in height and 20 kpc in radius centred on the disc of the galaxy. Overall, the properties of superbubbles are sensitive to the choice of subgrid galaxy formation models and can, therefore, be used to constrain these models. [ABSTRACT FROM AUTHOR]

Reliable indirect diagnostics of LyC photon escape from galaxies are required to understand which sources were the dominant contributors to reionization. While multiple LyC escape fraction (f esc) indicators have been proposed to trace favourable conditions for LyC leakage from the interstellar medium of low-redshift 'analogue' galaxies, it remains unclear whether these are applicable at high redshifts where LyC emission cannot be directly observed. Using a library of 14 120 mock spectra of star-forming galaxies with redshifts 4.64 ≤ z ≤ 10 from the SPHINX20 cosmological radiation hydrodynamics simulation, we develop a framework for the physics that leads to high f esc. We investigate LyC leakage from our galaxies based on the criteria that successful LyC escape diagnostics must (i) track a high-specific star formation rate, (ii) be sensitive to stellar population age in the range 3.5–10 Myr representing the times when supernova first explode to when LyC production significantly drops, and (iii) include a proxy for neutral gas content and gas density in the interstellar medium. O32, ΣSFR, MUV, and H β equivalent width select for one or fewer of our criteria, rendering them either necessary but insufficient or generally poor diagnostics. In contrast, UV slope (β), and E (B − V) match two or more of our criteria, rendering them good f esc diagnostics (albeit with significant scatter). Using our library, we build a quantitative model for predicting f esc based on direct observables. When applied to bright z > 6 Ly α emitters observed with JWST, we find that the majority of them have |$f_{\rm esc} \lesssim 10~{{\ \rm per\ cent}}$|⁠. [ABSTRACT FROM AUTHOR]

Atomic Hydrogen-21 cm transition (H  i) is an excellent tracer to study and understand the properties of the atomic gas in the Galaxy. Using the Westerbork Synthesis Radio Telescope, we observed 12 quasar sightlines to detect galactic H  i in absorption. We achieve an optical depth rms of ∼1−2 × 10−3, essential to detect the warm neutral medium (WNM). We detect H  i absorption in all our sightlines except along 1006+349, for which we set a strict upper limit on the spin temperature as 〈 T s〉 > 570 K. We find around 50 per cent of our sightlines have 〈 T s〉 > 500 K, indicating a WNM dominance. Further, we calculate an upper limit of the cold neutral medium (CNM) fraction along our sightlines and find a median CNM fraction of ∼0.12. With our observations, we reconfirm the existence of a threshold column density of ∼2 × 1020 |$\rm atoms \, cm^{-2}$| to form CNM in the interstellar medium (ISM). Using a two-temperature model of the H  i disc, we explore the distribution of spin temperature in the Galactic ISM. We find that a simple fixed axisymmetric two-temperature model could not produce either the observed column density or the integral optical depth. This indicates the existence of a more complex distribution of spin temperatures in the Galaxy. [ABSTRACT FROM AUTHOR]

In this study, we modify the semi-analytic model galacticus in order to accurately reproduce the observed properties of dwarf galaxies in the Milky Way. We find that reproducing observational determinations of the halo occupation fraction and mass–metallicity relation for dwarf galaxies requires us to include H2 cooling, an updated ultraviolet background radiation model, and to introduce a model for the metal content of the intergalactic medium. By fine-tuning various model parameters and incorporating empirical constraints, we have tailored the model to match the statistical properties of Milky Way dwarf galaxies, such as their luminosity function and size–mass relation. We have validated our modified semi-analytic framework by undertaking a comparative analysis of the resulting galaxy–halo connection. We predict a total of |$300 ^{+75} _{-99}$| satellites with an absolute V -band magnitude (MV) less than 0 within 300 kpc from our Milky Way analogues. The fraction of subhaloes that host a galaxy at least this bright drops to 50 per cent by a halo peak mass of ∼8.9 × 107 M⊙, consistent with the occupation fraction inferred from the latest observations of Milky Way satellite population. [ABSTRACT FROM AUTHOR]

Upcoming experiments will map the spatial distribution of the 21-cm signal over three-dimensional volumes of space during the Epoch of Reionization (EoR). Several methods have been proposed to mitigate the issue of astrophysical foreground contamination in tomographic images of the 21-cm signal, one of which involves the excision of a wedge-shaped region in cylindrical Fourier space. While this removes the k -modes most readily contaminated by foregrounds, the concurrent removal of cosmological information located within the wedge considerably distorts the structure of 21-cm images. In this study, we build upon a U-Net-based deep-learning algorithm to reconstruct foreground wedge-removed maps of the 21-cm signal, newly incorporating light-cone effects. Adopting the Square Kilometre Array as our fiducial instrument, we highlight that our U-Net recovery framework retains a reasonable level of reliability even in the face of instrumental limitations and noise. We subsequently evaluate the efficacy of recovered maps in guiding high-redshift galaxy searches and providing context to existing galaxy catalogues. This will allow for studies of how the high-redshift galaxy luminosity function varies across environments, and ultimately refine our understanding of the connection between the ionization state of the intergalactic medium and galaxies during the EoR. [ABSTRACT FROM AUTHOR]

Dust polarization observations at optical wavelengths help understand the dust grain properties and trace the plane-of-the-sky component of the magnetic field. In this study, we make use of published optical polarization data acquired with AIMPOL along with distances (d) and extinction (A V) data. We study the variation of polarization efficiency (P / A V) as a function of A V in the diffuse interstellar medium (ISM) and intracluster mediums (ICM) using the already published polarization data of six clusters. Among these clusters, NGC 2281, NGC 1664, and NGC 1960 are old; while Stock 8, NGC 1931, and NGC 1893 are young. We categorize stars towards each cluster into foreground, background, and cluster members by employing two clustering algorithms GMM and DBSCAN. Thus, classified field stars and cluster members are used to reveal the polarization properties of ISM and ICM dust, respectively. We find that the dust grains located in the diffuse ISM show higher polarization efficiencies when compared to those located in the ICM of younger clusters. [ABSTRACT FROM AUTHOR]

X-ray photons can penetrate deep into the intergalactic medium (IGM), leading to pre-heating of the IGM prior to cosmic reionization. X-ray pre-heating wipes out some of the small-scale structures that would otherwise be present prior to the passage of an ionization front. Accurate modelling of the small-scale structure is vital to the post-reionization IGM, since the small-scale structure is ultimately the dominant source of long-lasting relics from hydrogen reionization. However, the precise impact of X-ray pre-heating in the fossils from hydrogen reionization is highly uncertain. In this work, we explore and establish for the first time, the long-lasting impact of X-ray pre-heating in the post-reionization IGM via hydrodynamic simulations with high-mass resolution. We find that the addition of X-ray pre-heating astrophysics leads to an overall lesser impact of the effect of inhomogeneous reionization in the Lyα forest – depending on specific X-ray prescription – at low redshifts (z ∼ 2) with respect to a model with no X-ray pre-heating. However, at high redshifts (z ∼ 4), our results indicate a strengthening of the relics of reionization in the Lyα forest because the IGM becomes more transparent compared to the scenario with no pre-heating. Thus, the absence of X-ray pre-heating in Lyα modelling can lead to a biased inference of cosmological parameters. Nevertheless, optimistically, the inclusion of X-ray pre-heating emerges as a promising novel avenue to probe the astrophysics of cosmic dawn. [ABSTRACT FROM AUTHOR]

In eclipsing X-ray binary systems, the direct X-ray emission is blocked by the companion star during the eclipse. We observe only reprocessed emission that contains clues about the environment of the compact object and its chemical composition, ionization levels, etc. We have found flares in some X-ray binaries during their eclipses. The study of eclipse flares provides additional clues regarding the size of the reprocessing region and helps distinguish between different components of the X-ray spectrum observed during the eclipse. In the archival data, we searched for flares during eclipses of high-mass X-ray binaries and found flares in three sources: Vela X-1, LMC X-4, and 4U 1700−37. Comparing spectral properties of the eclipse flare and non-flare data, we found changes in the power-law photon index in all three sources and multiple emission lines in Vela X-1 and 4U 1700-37. The fluxes of prominent emission lines showed a similar increase as the overall X-ray flux during the eclipse flare, suggesting the lines originate in the binary environment and not in the interstellar medium. We also observed a soft excess in 4U 1700-37 that remains unchanged during both eclipse flare and non-flare states. Our analysis suggests that this emission originates from the extremely thin shell of the stellar wind surrounding the photosphere of its companion star. The detection of short (100–200 s) count-rate doubling time-scale in 4U 1700−37 and LMC X-4 indicates that the eclipse reprocessing occurs in a region larger than, but comparable to the size of the companion star. [ABSTRACT FROM AUTHOR]

The metal content of galaxies provides a window into their formation in the full context of the cosmic baryon cycle. In this study, we examine the relationship between stellar mass and stellar metallicity (MZ*R) in the hydrodynamic simulations Illustris, TNG, and EAGLE (Evolution and Assembly of GaLaxies and their Environment) to understand the global properties of stellar metallicities within the feedback paradigm employed by these simulations. Interestingly, we observe significant variations in the overall normalization and redshift evolution of the MZ*R across the three simulations. However, all simulations consistently demonstrate a tertiary dependence on the specific star formation rate (sSFR) of galaxies. This finding parallels the relationship seen in both simulations and observations between stellar mass, gas-phase metallicity, and some proxy of galaxy gas content (e.g. SFR, gas fraction, and atomic gas mass). Since we find this correlation exists in all three simulations, each employing a subgrid treatment of the dense, star-forming interstellar medium (ISM) to simulate smooth stellar feedback, we interpret this result as a fairly general feature of simulations of this kind. Furthermore, with a toy analytic model, we propose that the tertiary correlation in the stellar component is sensitive to the extent of the 'burstiness' of feedback within galaxies. [ABSTRACT FROM AUTHOR]

We investigated the gas obscuration and host galaxy properties of active galactic nuclei (AGNs) during the peak of cosmic accretion growth of supermassive black holes at redshift 0.8–1.8 using X-ray-detected AGNs with mid-infrared and far-infrared detection. The sample was classified as type-1 and type-2 AGNs using optical spectral and morphological classification while the host galaxy properties were estimated with multiwavelength spectral energy distribution fitting. For type-1 AGNs, the black hole mass was determined from MgII emission lines while the black hole mass of type-2 AGNs was inferred from the host galaxy's stellar mass. Based on the derived parameters, the distribution of the sample in the absorption hydrogen column density (N H) versus Eddington ratio diagram is examined. Among the type-2 AGNs, 28 ± 5 per cent are in the forbidden zone, where the obscuration by dust torus cannot be maintained due to radiation pressure on dusty material. The fraction is higher than that observed in the local universe from the Burst Alert Telescope AGN Spectroscopic Survey data release 2 (BASS DR2) (11 ± 3 per cent). The higher fraction implies that the obscuration of the majority of AGNs is consistent with the radiation pressure regulated unified model but with an increased incidence of interstellar matter (ISM)-obscured AGNs. We discuss the possibility of dust-free absorption in type-1 AGNs and heavy ISM absorption in type-2 AGNs. We also find no statistical difference in the star-formation activity between type-1 and type-2 AGNs which may suggest that obscuration triggered by a gas-rich merging is not common among X-ray detected AGNs in this epoch. [ABSTRACT FROM AUTHOR]

Understanding the origin of the diffuse flux of high-energy astrophysical neutrinos detected by IceCube has become a challenging issue within present High Energy Astrophysics. In this work, we present a model to explore the potential neutrino emission of starburst galaxies (SBG) by considering three different neutrino production zones that can be associated to a typical single SBG. The first zone is the starburst nucleus, where due to the high rate of supernova explosions, a significant amount of protons can be accelerated to high energies and undergo pp interactions with cold protons of the interstellar medium. The second zone we consider is the corresponding to the starburst wind, which is formed by the hot gas that emerges from the nucleus and interacts with the intergalactic medium generating shocks. Protons accelerated there can undergo pp interactions with the ambient matter. The third neutrino production zone we consider, is an external one, where we account for the possibility that protons escaping from the whole system interact with the cosmic microwave background. Finally, adding the neutrino contributions of the three zones, we calculate the diffuse neutrino flux and the diffuse photon flux by integration on the redshift range appropriate for SBG. We find that the model behaves well applied to nearby galaxies such as M82 and NGC 253. The contributions made to the diffuse neutrino flux are able to explain part of the data provided by IceCube if typical parameters are considered. [ABSTRACT FROM AUTHOR]

Observations of high-redshift quasars hosting billion solar mass black holes at z ≳ 6 challenge our understanding of early supermassive black hole (SMBH) growth. In this work, we conduct a near-infrared spectroscopic study of 19 quasars at 6.2 ≲ z ≲ 7.5, using the Folded-port InfraRed Echellette instrument on the 6.5-m Magellan/Baade Telescope. We estimate the single-epoch masses of the quasars' SMBHs by means of the Mg  ii emission line and find black hole masses of |$M_{\text{BH}} \approx (0.2\!\!-\!\!4.8)\, \times \, 10^9\ \mathrm{ M}_\odot$|⁠. Furthermore, we measure the sizes of the quasars' proximity zones, which are regions of enhanced transmitted flux bluewards of the Ly  |$\alpha \,$| emission line, ionized by the quasars' radiation itself. While it has been shown that the proximity zone sizes correlate with the quasars' lifetimes due to the finite response time of the intergalactic medium to the quasars' radiation, we do not find any correlation between the proximity zone sizes and the black hole mass, which suggests that quasar activity and the concomitant black hole growth are intermittent and episodic. [ABSTRACT FROM AUTHOR]

A recent work [Ye et al. Mon. Not. R. Astron. Soc.2023, 525, 1158] on the gas‐phase formation of t‐HC(O)SH, already detected in the interstellar medium, pointed out that the trans form of HC(S)OH is a potential candidate for astronomical observations. Prompted by these results, the CH2SO family of isomers has been investigated from an energetic point of view using a double‐hybrid density functional in combination with a partially augmented triple‐zeta basis set. This preliminary study showed that the most stable species of the family are the cis and trans forms of HC(O)SH and HC(S)OH. For their structural and spectroscopic characterization, a composite scheme based on coupled cluster (CC) calculations that incorporates up to the quadruple excitations and accounts for the extrapolation to the complete basis set limit and core correlation effects has been employed. This approach opens to the prediction of rotational constants with an accuracy of 0.1%. A hybrid scheme, based on harmonic frequencies computed using the CC singles, doubles and a perturbative treatment of triples method (CCSD(T)) in conjunction with a quadruple‐zeta basis set, allowed us to obtain fundamental vibrational frequencies with a mean absolute error of about 1%. [ABSTRACT FROM AUTHOR]

Dust-obscured star formation has dominated the cosmic history of star formation, since z ≃ 4 . However, the recent finding of significant amount of dust in galaxies out to z ≃ 8 has opened the new frontier of investigating the origin of dust also in the earliest phases of galaxy formation, within the first 1.5 billion years from the Big Bang. This is a key and rapid transition phase for the evolution of dust, as galaxy evolutionary timescales become comparable with the formation timescales of dust. It is also an area of research that is experiencing an impressive growth, especially thanks to the recent results from cutting edge observing facilities, ground-based, and in space. Our aim is to provide an overview of the several findings on dust formation and evolution at z > 4 , and of the theoretical efforts to explain the observational results. We have organized the review in two parts. In the first part, presented here, we focus on dust sources, primarily supernovae and asymptotic giant branch stars, and the subsequent reprocessing of dust in the interstellar medium, through grain destruction and growth. We also discuss other dust production mechanisms, such as Red Super Giants, Wolf–Rayet stars, Classical Novae, Type Ia Supernovae, and dust formation in quasar winds. The focus of this first part is on theoretical models of dust production sources, although we also discuss the comparison with observations in the nearby Universe, which are key to put constraints on individual sources and processes. While the description has a general applicability at any redshift, we emphasize the relative role of different sources in the dust build-up in the early Universe. In the second part, which will be published later on, we will focus on the recent observational results at z > 4 , discussing the theoretical models that have been proposed to interpret those results, as well as the profound implications for galaxy formation. [ABSTRACT FROM AUTHOR]

Massive elliptical galaxies harbor large amounts of hot gas (T ≳ 106 K) in their interstellar medium (ISM) but are typically quiescent in star formation. The jets of active galactic nuclei (AGNs) and Type Ia supernovae (SNe Ia) inject energy into the ISM, which offsets its radiative losses and keeps it hot. SNe Ia deposit their energy locally within the galaxy compared to the larger few ×10 kiloparsec-scale AGN jets. In this study, we perform high-resolution (5123) hydrodynamic simulations of a local (1 kpc3) density-stratified patch of the ISM of massive galaxies. We include radiative cooling and shell-averaged volume heating, as well as randomly exploding SN Ia. We study the effect of different fractions of supernova (SN) heating (with respect to the net cooling rate), different initial ISM density/entropy (which controls the growth time t ti of the thermal instability), and different degrees of stratification (which affect the freefall time t ff). We find that SNe Ia drive predominantly compressive turbulence in the ISM with a velocity dispersion of σ v up to 40 km s−1 and logarithmic density dispersion of σ s ∼ 0.2–0.4. These fluctuations trigger multiphase condensation in regions of the ISM, where min (t ti) / t ff ≲ 0.6 exp (6 σ s) , in agreement with theoretical expectations that large density fluctuations efficiently trigger multiphase gas formation. Since the SN Ia rate is not self-adjusting, when the net cooling drops below the net heating rate, SNe Ia drive a hot wind which sweeps out most of the mass in our local model. Global simulations are required to assess the ultimate fate of this gas. [ABSTRACT FROM AUTHOR]

Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations have revealed an increasing number of compact protostellar disks with radii of less than a few tens of astronomical units and that young Class 0/I objects have an intrinsic size diversity. To deepen our understanding of the origin of such tiny disks, we have performed highest-resolution configuration observations with ALMA at a beam size of ∼0.″03 (4 au) on the very low-luminosity Class 0 protostar embedded in the Taurus dense core MC 27/L1521F. The 1.3 mm continuum measurement successfully resolved a tiny, faint (∼1 mJy) disk with a major axis length of ∼10 au, one of the smallest examples in the ALMA protostellar studies. In addition, we detected spike-like components in the northeastern direction at the disk edge. Gravitational instability or other fragmentation mechanisms cannot explain the structures, given the central stellar mass of ∼0.2 M ⊙ and the disk mass of ≳10−4 M ⊙. Instead, we propose that these small spike structures were formed by a recent dynamic magnetic flux transport event due to interchange instability that would be favorable to occur if the parental core has a strong magnetic field. The presence of complex arc-like structures on a larger (∼2000 au) scale in the same direction as the spike structures suggests that the event was not single. Such episodic, dynamical events may play an important role in maintaining the compact nature of the protostellar disk in the complex gas envelope during the main accretion phase. [ABSTRACT FROM AUTHOR]