Intergalactic Medium Research Articles

Signatures of high-redshift galactic outflows in the thermal Sunyaev Zel’dovich effect

Abstract Anisotropies of the Sunyaev Zel’dovich (SZ) effect serve as a powerful probe of the thermal history of the universe. At high redshift, hot galactic outflows driven by supernovae (SNe) can inject a significant amount of thermal energy into the intergalactic medium, causing a strong y-type distortion of the CMB spectrum through inverse Compton scattering. The resulting anisotropies of the y-type distortion are sensitive to key physical properties of high-z galaxies pertaining to the launch of energetic SNe-driven outflows, such as the efficiency and the spatio-temporal clustering of star formation. We develop a simple analytic framework to calculate anisotropies of y-type distortion associated with SNe-powered outflows of galaxies at z > 6. We show that galactic outflows are likely the dominant source of thermal energy injection, compared to contributions from reionized bubbles and gravitational heating. We further show that next-generation CMB experiments such as LiteBIRD are likely to detect the contribution to y anisotropies from high-z galactic outflows through the cross-correlation with surveys of Lyman-break galaxies by e.g. the Roman Space Telescope. Our analysis and forecasts demonstrate that thermal SZ anisotropies can be a promising probe of SN feedback and outflows in early star-forming galaxies.

Reionization morphology and intrinsic velocity offsets allow transmission of Lyman-α emission from JADES-GS-z13-1-LA

ABSTRACT We investigate the detectability of Lyman-$\alpha$ (Ly $\alpha$) emission from galaxies at the onset of cosmic reionization, aiming to understand the conditions necessary for detecting high-redshift sources like JADES-GS-z13-1-LA at $z=13$. By integrating galaxy formation models with detailed intergalactic medium (IGM) reionization simulations, we construct high-redshift galaxy catalogues to model intrinsic Ly $\alpha$ profiles and assess their transmission through the IGM. For a galaxy with $M_{\rm UV}\sim -18.5$ like JADES-GS-z13-1-LA, our fiducial model predicts a Ly $\alpha$ transmission of ${\sim }13$ per cent and there is a probability of observing Ly $\alpha$ emission with an equivalent width $\gt 40$ Å of up to 10 per cent. We also explore how variations in the UV ionizing escape fraction, dependent on host halo mass or specific star formation rate, impact Ly $\alpha$ detectability. Our findings reveal that reionization morphology significantly influences detection chances – models where reionization is driven by low-mass galaxies can boost the detection probability to as much as 12 per cent, while those driven by massive galaxies tend to reduce ionized regions around faint emitters, limiting their detectability. Our findings remain robust when further accounting for stochastic star formation with the detection probability still spanning 3 per cent to 12 per cent. This study underscores the interplay between reionization morphology and intrinsic galaxy properties in interpreting high-redshift Ly $\alpha$ observations.

Searching for HI around MHONGOOSE galaxies via spectral stacking

The observed star formation rates of galaxies in the Local Universe suggests that they are replenishing their gas reservoir across cosmic time. Cosmological simulations predict that this accretion of fresh gas can occur in a hot or a cold mode, yet the existence of low column density (∼1017 cm−2) neutral atomic hydrogen (HI) tracing the cold mode has not been unambiguously confirmed by observations. We present the application of unconstrained spectral stacking to attempt to detect the emission from this HI in the circumgalactic medium (CGM) and intergalactic medium (IGM) of six nearby star-forming galaxies from the MHONGOOSE sample for which full-depth observations are available. Our stacking procedure consists of a standard spectral stacking algorithm coupled with a one-dimensional spectral line finder designed to extract a reliable signal close to the noise level. In agreement with previous studies, we find that the amount of signal detected outside the HI disk is much smaller than implied by simulations. Furthermore, the column density limit that we achieve via stacking (∼1017 cm−2) suggests that direct detection of the neutral CGM and IGM component might be challenging in the future, even with the next generation of radio telescopes.

Determining the absolute chemical abundance of nitrogen and sulfur in the quasar outflow of 3C298

Context. Quasar outflows are key players in the feedback processes that influence the evolution of galaxies and the intergalactic medium. The chemical abundance of these outflows provides crucial insights into their origin and impact. Aims. We determine the absolute abundances of nitrogen and sulfur and the physical conditions of the outflow seen in quasar 3C298. Methods. We analyzed archival spectral data from the Hubble Space Telescope for 3C298. We measured the ionic column densities from the absorption troughs and compared the results to photoionization predictions made with the Cloudy code for three different spectral energy distributions (SEDs), including MF87, UV-soft, and HE0238 SEDs. We also calculated the ionic column densities of the excited and ground states of N III to estimate the electron number density and location of the outflow using the Chianti atomic database. Results. The MF87, UV-soft, and HE0238 SEDs yield nitrogen and sulfur abundances at supersolar, solar, and subsolar values, respectively, with a spread of 0.4–3 times solar. Additionally, we determined an electron number density of log(ne)≥3.3 cm−3, and the outflow might extend up to a maximum distance of 2.8 kpc. Conclusions. Our results indicate a solar metallicity within an uncertainty range of 60% that is driven by variations in the chosen SED and photoionization models. This study underscores the importance of the SED impact on determining chemical abundances in quasar outflows. These findings highlight the necessity of considering a wider range of possible abundances that span from subsolar to supersolar values.

Quantifying Lyman-α emissions from reionization fronts

Abstract During reionization, intergalactic ionization fronts (I-fronts) are sources of Lyα line radiation produced by collisional excitation of hydrogen atoms within the fronts. In principle, detecting this emission could provide direct evidence for a reionizing intergalactic medium (IGM). In this paper, we use a suite of high-resolution one-dimensional radiative transfer simulations run on cosmological density fields to quantify the parameter space of I-front Lyα emission. We find that the Lyα production efficiency — the ratio of emitted Lyα flux to incident ionizing flux driving the front — depends mainly on the I-front speed and the spectral index of the ionizing radiation. IGM density fluctuations on scales smaller than the typical I-front width produce scatter in the efficiency, but they do not significantly boost its mean value. The Lyα flux emitted by an I-front is largest if 3 conditions are met simultaneously: (1) the incident ionizing flux is large; (2) the incident spectrum is hard, consisting of more energetic photons; (3) the I-front is traveling through a cosmological over-density, which causes it to propagate more slowly. We present a convenient parameterization of the efficiency in terms of I-front speed and incident spectral index. We make these results publicly available as an interpolation table and we provide a simple fitting function for a representative ionizing background spectrum. Our results can be applied as a sub-grid model for I-front Lyα emissions in reionization simulations with spatial and/or temporal resolutions too coarse to resolve I-front structure. In a companion paper, we use our results to explore the possibility of directly imaging Lyα emission around neutral islands during the last phases of reionization.

Imaging reionization's last phases with I-front Lyman-α emissions

Long troughs observed in the z > 5.5 Lyα and Lyβ forests are thought to be caused by the last remaining neutral patches during the end phases of reionization — termed neutral islands. If this is true, then the longest troughs mark locations where we are most likely to observe the reionizing intergalactic medium (IGM). A key feature of the neutral islands is that they are bounded by ionization fronts (I-fronts) which emit Lyman series lines. In this paper, we explore the possibility of directly imaging the outline of neutral islands with a narrowband survey targeting Lyα. In a companion paper, we quantified the intensity of I-front Lyα emissions during reionization and its dependence on the spectrum of incident ionizing radiation and I-front speed. Here we apply those results to reionization simulations to model the emissions from neutral islands. We find that neutral islands would appear as diffuse structures that are tens of comoving Mpc across, with surface brightnesses in the range ≈ 1 - 5× 10-21 erg s-1 cm-2 arcsec-2. The islands are brighter if the spectrum of ionizing radiation driving the I-fronts is harder, and/or if the I-fronts are moving faster. We develop mock observations for current and futuristic observatories and find that, while extremely challenging, detecting neutral islands is potentially within reach of an ambitious observing program with wide-field narrowband imaging. Our results demonstrate the potentially high impact of low-surface brightness observations for studying reionization.

Combined Fit of Spectrum and Composition for FR0 Radio-galaxy-emitted Ultra–high energy Cosmic Rays with Resulting Secondary Photons and Neutrinos

This study comprehensively investigates the gamma-ray dim population of Fanaroff–Riley Type 0 (FR0) radio galaxies as potentially significant sources of ultra–high energy cosmic rays (UHECRs, E > 1018 eV) detected on Earth. While individual FR0 luminosities are relatively low compared to the more powerful Fanaroff–Riley Type 1 and Type 2 galaxies, FR0s are substantially more prevalent in the local universe, outnumbering the more energetic galaxies by a factor of ∼5 within a redshift of z ≤ 0.05. Employing CRPropa3 simulations, we estimate the mass composition and energy spectra of UHECRs originating from FR0 galaxies for energies above 1018.6 eV. This estimation fits data from the Pierre Auger Observatory (Auger) using three extensive air shower models; both constant and energy-dependent observed elemental fractions are considered. The simulation integrates an approximately isotropic distribution of FR0 galaxies, extrapolated from observed characteristics, with UHECR propagation in the intergalactic medium, incorporating various plausible configurations of extragalactic magnetic fields, both random and structured. We then compare the resulting emission spectral indices, rigidity cutoffs, and elemental fractions with recent Auger results. In total, 25 combined energy-spectrum and mass-composition fits are considered. Beyond the cosmic-ray fluxes emitted by FR0 galaxies, this study predicts the secondary photon and neutrino fluxes from UHECR interactions with intergalactic cosmic photon backgrounds. The multimessenger approach, encompassing observational data and theoretical models, helps elucidate the contribution of low-luminosity FR0 radio galaxies to the total cosmic-ray energy density.

Neutral fraction of hydrogen in the intergalactic medium surrounding high-redshift gamma-ray burst 210905A

ABSTRACT The Epoch of Reionization (EoR) is a key period of cosmological history in which the intergalactic medium (IGM) underwent a major phase change from being neutral to almost completely ionized. Gamma-ray bursts (GRBs) are luminous and unique probes of their environments that can be used to study the timeline for the progression of the EoR. Here, we present a detailed analysis of the European Southern Observatory Very Large Telescope X-shooter spectrum of GRB 210905A, which resides at a redshift of $z\sim 6.3$. We focus on estimating the fraction of neutral hydrogen, $x_{\rm H \, {\small I}}$, on the line of sight to the host galaxy of GRB 210905A by fitting the shape of the Lyman-$\alpha$ damping wing of the afterglow spectrum. The X-shooter spectrum has a high signal-to-noise ratio, but the complex velocity structure of the host galaxy limits the precision of our conclusions. The statistically preferred model suggests a low neutral fraction with a 3$\sigma$ upper limit of $x_{\rm H \, {\small I}} \lesssim 0.15$ or $x_{\rm H \, {\small I}} \lesssim 0.23$, depending on the absence or presence of an ionized bubble around the GRB host galaxy, indicating that the IGM around the GRB host galaxy is mostly ionized. We discuss complications in current analyses and potential avenues for future studies of the progression of the EoR and its evolution with redshift.

Neural network emulator to constrain the high-z IGM thermal state from Lyman-α forest flux autocorrelation function

ABSTRACT We present a neural network emulator to constrain the thermal parameters of the intergalactic medium (IGM) at $5.4 \le z \le 6.0$ using the Lyman-$\alpha$ (Ly $\alpha$) forest flux autocorrelation function. Our autodifferentiable JAX-based framework accelerates the surrogate model generation process using approximately 100 sparsely sampled Nyx hydrodynamical simulations with varying combinations of thermal parameters, i.e. the temperature at mean density $T_0$, the slope of the temperature–density relation $\gamma$, and the mean transmission flux $\langle F \rangle$. We show that this emulator has a typical accuracy of 1.0 per cent across the specified redshift range. Bayesian inference of the IGM thermal parameters, incorporating emulator uncertainty propagation, is further expedited using NumPyro Hamiltonian Monte Carlo. We compare both the inference results and computational cost of our framework with the traditional nearest-neighbour interpolation approach applied to the same set of mock Ly $\alpha$ flux. By examining the credibility contours of the marginalized posteriors for $T_0, \gamma , \text{and}~\langle F \rangle$ obtained using the emulator, the statistical reliability of measurements is established through inference on 100 realistic mock data sets of the autocorrelation function.

Reionization relics in the cross-correlation between the Lyα forest and 21 cm intensity mapping in the post-reionization era

Abstract The tumultuous effects of ultraviolet photons that source cosmic reionization, the subsequent compression and shock-heating of low-density regions, and the modulation of baryons in shallow potential wells induced by the passage of ionization fronts, collectively introduce perturbations to the evolution of the intergalactic medium in the post-reionization era. These enduring fluctuations persist deep into the post-reionization era, casting a challenge upon precision cosmology endeavors targeting tracers in this cosmic era. Simultaneously, these relics from reionization also present a unique opportunity to glean insights into the astrophysics that govern the epoch of reionization. In this work, we propose a first study of the cross-correlation of Lyα forest and 21 cm intensity mapping, accounting for the repercussions of inhomogeneous reionization in the post-reionization era. We investigate the ability of SKA × DESI-like, SKA × MUST-like, and PUMA × MUST-like instrumental setups to achieve a high signal-to-noise ratio (SNR) in the redshift range 3.5 ≤ z ≤ 4. Moreover, we assess how alterations in integration time, survey area, and reionization scenarios impact the SNR. Furthermore, we forecast the cross-correlation’s potential to constrain cosmological parameters under varying assumptions: considering or disregarding reionization relics, marginalizing over reionization astrophysics, and assuming perfect knowledge of reionization. Notably, our findings underscore the remarkable capability of a futuristic PUMA × MUST-like setup, with a modest 100-hour integration time over a 100 sq. deg. survey, to constrain the ionization efficiency error to σζ = 3.42.

FlexRT — A fast and flexible cosmological radiative transfer code for reionization studies. Part I. Code validation

The wealth of high-quality observational data from the epoch of reionization that will become available in the next decade motivates further development of modeling techniques for their interpretation. Among the key challenges in modeling reionization are (1) its multi-scale nature, (2) the computational demands of solving the radiative transfer (RT) equation, and (3) the large size of reionization's parameter space. In this paper, we present and validate a new RT code designed to confront these challenges. FlexRT (Flexible Radiative Transfer) combines adaptive ray tracing with a highly flexible treatment of the intergalactic ionizing opacity. This gives the user control over how the intergalactic medium (IGM) is modeled, and provides a way to reduce the computational cost of a FlexRT simulation by orders of magnitude while still accounting for small-scale IGM physics. Alternatively, the user may increase the angular and spatial resolution of the algorithm to run a more traditional reionization simulation. FlexRT has already been used in several contexts, including simulations of the Lyman-α forest of high-z quasars, the redshifted 21cm signal from reionization, as well as in higher resolution reionization simulations in smaller volumes. In this work, we motivate and describe the code, and validate it against a set of standard test problems from the Cosmological Radiative Transfer Comparison Project. We find that FlexRT is in broad agreement with a number of existing RT codes in all of these tests. Lastly, we compare FlexRT to an existing adaptive ray tracing code to validate FlexRT in a cosmological reionization simulation.

Intergalactic Medium Rotation Measure of Primordial Magnetic Fields

The Faraday rotation effect, quantified by the rotation measure (RM), is a powerful probe of the large-scale magnetization of the Universe—tracing magnetic fields not only on galaxy and galaxy cluster scales but also in the intergalactic medium (IGM; referred to as RMIGM). The redshift dependence of the latter has extensively been explored with observations. It has also been shown that this relation can help to distinguish between different large-scale magnetization scenarios. We study the evolution of this RMIGM for different primordial magnetogenesis scenarios to search for the imprints of primordial magnetic fields (PMFs; magnetic fields originating in the early Universe) on the redshift-dependence of RMIGM. We use cosmological magnetohydrodynamic simulations for evolving PMFs during large-scale structure formation, coupled with the light-cone analysis to produce a realistic statistical sample of mock RMIGM images. We study the predicted behavior for the cosmic evolution of RMIGM for different correlation lengths of PMFs, and provide fitting functions for their dependence on redshifts. We compare these mock RM trends with the recent analysis of the the LOw-Frequency ARray RM Grid and find that large-scale-correlated PMFs should have (comoving) strengths ≲0.75 nG, if they originated during inflation with the scale-invariant spectrum and (comoving) correlation length of ∼19 h −1 cMpc or ≲30 nG if they originated during phase-transition epochs with the comoving correlation length of ∼1 h −1 cMpc. Our findings agree with previous observations and confirm the results of semi-analytical studies, showing that upper limits on the PMF strength decrease as their coherence scales increase.

NIHAO-RiNG: A Comparison of Simulated Disk Galaxies from GASOLINE and GIZMO

We utilize the publicly available code GIZMO to re-simulate 12 galaxies selected from the Numerical Investigation of a Hundred Astronomical Object (NIHAO) simulation suite, which were run with the GASOLINE code, then compare their properties. We find that while both codes with the same initial conditions and large-scale environments can successfully produce similar galactic disks in Milky Way-mass systems, yet significant differences are still seen in many aspects, particularly the circumgalactic medium (CGM) environment they reside in. Specifically, the thermal feedback recipe used in GASOLINE results in ubiquitous, long-term, large-scale outflows, primarily driven by high-density hot interstellar medium from the galaxy center, preventing the intergalactic medium from falling efficiently. Recycled gas and inflows in the CGM appear at 104∼5 K, playing a crucial role in the formation of cold disks in the NIHAO simulations. In contrast, disk galaxies simulated by GIZMO do not exhibit prominent outflows at low redshifts, but instead display quasi-virialized hot gas halos that arise from the interaction between inflows and feedback-driven outflows. Therefore, the origins of mass and angular momentum of the cold disk in the two simulations are quite different, even though the final morphologies of the corresponding galaxies are both disky. The differences in the distribution of CGM gas are mainly due to different feedback models implemented in the two codes. Future observations of CGM could provide valuable insight into the physics governing the baryon cycle in galaxies.

JADES: measuring reionization properties using Lyman-alpha emission

ABSTRACT Ly$\alpha$ is the transition to the ground state from the first excited state of hydrogen (the most common element). Resonant scattering of this line by neutral hydrogen greatly impedes its emergence from galaxies, so the fraction of galaxies emitting Ly$\alpha$ is a tracer of the neutral fraction of the intergalactic medium (IGM), and thus the history of reionization. In previous works, we used early JWST/NIRSpec data from the JWST Advanced Deep Extragalactic Survey (JADES) to classify and characterize Ly$\alpha$ emitting galaxies (LAEs). This survey is approaching completion, and the current sample is nearly an order of magnitude larger. From a sample of 795 galaxies in JADES at $4.0\lt z\lt 14.3$, we find evidence for Ly$\alpha$ emission in 150 sources. We reproduce the previously found correlation between Ly$\alpha$ escape fraction ($f\rm _{esc}^{Ly\alpha }$) – Ly$\alpha$ rest-frame equivalent width (${\rm REW}_{\rm Ly\alpha }$) and the negative correlation between Ly$\alpha$ velocity offset – $f\rm _{esc}^{Ly\alpha }$. Both $f\rm _{esc}^{Ly\alpha }$ and ${\rm REW}_{\rm Ly\alpha }$ decrease with redshift ($z\gtrsim 5.5$), indicating the progression of reionization on a population scale. Our data are used to demonstrate an increasing IGM transmission of Ly$\alpha$ from $z\sim 14-6$. We measure the completeness-corrected fraction of LAEs ($X\rm _{Ly\alpha }$) from $z=4-9.5$. An application of these $X\rm _{Ly\alpha }$ values to the results of previously utilized semi-analytical models suggests a high neutral fraction at $z=7$ (${X_{\rm HI}}\sim 0.8-0.9$). Using an updated fit to the intrinsic distribution of ${\rm REW}_{\rm Ly\alpha }$ results in a lower value in agreement with current works (${X_{\rm HI}}= 0.64_{-0.21}^{+0.13}$). This sample of LAEs will be paramount for unbiased population studies of galaxies in the EoR.

Multiwavelength investigations of PKS 2300−18: S-shaped radio quasar with precessing jets and double peaked broad emission line spectrum

Abstract S-shaped radio galaxy jets are prime sources for investigating the dynamic interplay between the central active galactic nucleus, the jets, and the ambient intergalactic medium. These sources are excellent candidates for studying jet precession, as their S-shaped inversion symmetry strongly indicates underlying precession. We present a multiwavelength analysis of the giant inversion-symmetric S-shaped radio galaxy PKS 2300−18, which spans 0.76 Mpc. The host is a quasar at a redshift of 0.128, displaying disturbed optical morphology due to an ongoing merger with a companion galaxy. We conducted a broadband radio spectral study using multifrequency data ranging from 183 MHz to 6 GHz, incorporating dedicated observations with the uGMRT and JVLA alongside archival radio data. Particle injection model was fitted to the spectra of different regions of the source to perform ageing analysis, which was supplemented with a kinematic jet precession model. The ageing analysis revealed a maximum plasma age of ∼ 40 Myr, while the jet precession model indicated a precession period of ∼ 12 Myr. ROSAT data revealed an X-ray halo of Mpc size, and from Chandra the AGN X-ray spectrum was modelled using thermal and power law components. The optical spectrum displaying double peaked broad emission lines was modelled, indicating complex broad line region kinematics at the centre with the possibility of a binary SMBH. We present the results of our multiwavelength analysis of the source, spanning scales from a few light days to a few Mpc, and discuss its potential evolutionary path.

Constraining the Hubble constant with scattering in host galaxies of fast radio bursts

Measuring the Hubble constant ($ H $) is one of the most important missions in astronomy. Nevertheless, recent studies exhibit differences between the employed methods. Fast radio bursts (FRBs) are coherent radio transients with large dispersion measures (DM) with a duration of milliseconds. DM$_ IGM $, the free electron column density along a line of sight in the intergalactic medium (IGM), could open a new avenue for probing $ H $. However, it has been challenging to separate DM contributions from different components (i.e., the IGM and the host galaxy plasma), and this hampers the accurate measurements of DM$_ IGM $ and hence $ H $. We adopted a method to overcome this problem by using the temporal scattering of the FRB pulses due to the propagation effect through the host galaxy plasma (scattering time). The scattering-inferred DM in a host galaxy improves the estimate of DM$_ IGM $, which in turn leads to a better constraint on $ H $. In previous studies, a certain value or distribution has conventionally been assumed of the dispersion measure in host galaxies (DM$_ h $). We compared this method with ours by generating 100 mock FRBs, and we found that our method reduces the systematic (statistical) error of H$_0$ by 9.1$<!PCT!>$ (1$<!PCT!>$) compared to the previous method. We applied our method to 30 localized FRB sources with both scattering and spectroscopic redshift measurements to constrain H$_0$. Our result is H$_0$ = 74$_ $ km s$^ $ Mpc$^ $, where the central value prefers the value obtained from local measurements over the cosmic microwave background. We also measured DM$_ h $ with a median value of $103^ $ pc cm$^ The $ DM_h $ had to be assumed in previous works to derive DM$_ IGM $. Scattering enables us to measure $ IGM $ without assuming DM$_ h $ to constrain H$_0$. The reduction in systematic error is comparable to the Hubble tension ($ Combined with the fact that more localized FRBs will become available, our result indicates that our method can be used to address the Hubble tension using future FRB samples.

The Composite Spectral Energy Distribution of Quasars Is Surprisingly Universal Since Cosmic Noon

Leveraging the photometric data of the Sloan Digital Sky Survey and the Galaxy Evolution Explorer (GALEX), we construct mean/median spectral energy distributions (SEDs) for unique bright quasars in redshift bins of 0.2 and up to z≃3, after taking the GALEX non-detection into account. Further correcting for the absorption of the intergalactic medium, these mean/median quasar SEDs constitute a surprisingly redshift-independent mean/median composite SED from the rest-frame optical down to ≃500 A˚ for quasars with bolometric luminosity brighter than 1045.5ergs−1. Moreover, the mean/median composite quasar SED is plausibly also independent of black hole mass and Eddington ratio, and suggests similar properties of dust and gas in the quasar host galaxies since cosmic noon. Both the mean and median composite SEDs are nicely consistent with previous mean composite quasar spectra at wavelengths beyond ≃1000 A˚, but at shorter wavelengths, are redder, indicating, on average, less ionizing radiation than previously expected. Through comparing the model-predicted to the observed composite quasar SEDs, we favor a simply truncated disk model, rather than a standard thin disk model, for the quasar central engine, though we request more sophisticated disk models. Future deep ultraviolet facilities, such as the China Space Station Telescope and the Ultraviolet Explorer, would prompt revolutions in many aspects, including the quasar central engine, production of the broad emission lines in quasars, and cosmic reionization.

On the Andromeda-Milky Way Future Encounter: Thrice Faster Over Time

This inquiry accurately provides an analytical solution of the orbital free-falling time for the system of galaxies Andromeda-Milky Way within a non-expanding tired-light-dominated framework. The mathematical and physical background involves a two-body problem based on the orbital dynamics in which, in the first scenario, the gravitational interaction between local galaxies dominates over the expanding space. The latter is the standard astrophysical approach undertaken by public fund-based universities all over the world. However, in the second alternative scenario, Andromeda’s blueshift has to be corrected for the apparent recession velocity provided by the photon energy loss as a result of multiple interactions between photons and crystallized electrons through the intergalactic medium provided by a Tired Light, specifically, a New Tired Light process. This leads towards a substantial temporal deviation between the classic research approach and this unconventional and independent mindset. Hence, the outcome gives out a disagreement consisting in an orbital free-falling time equal to 1.7 rather than 4.5 billion years. Accordingly, the encounter of the two main galaxies of the Local Group will occur much earlier than estimated thus far. Accordingly, this implies an urgent shift in the scientific mindset as well as a course change in the application of the boundary conditions into forthcoming computational methods.

JADES: primaeval Lyman α emitting galaxies reveal early sites of reionization out to redshift z ~ 9

ABSTRACT Given the sensitivity of the resonant Lyman $\alpha$ (Ly $\alpha $) transition to absorption by neutral hydrogen, observations of Ly $\alpha$ emitting galaxies (LAEs) have been widely used to probe the ionizing capabilities of reionization-era galaxies and their impact on the intergalactic medium (IGM). However, prior to JWST our understanding of the contribution of fainter sources and of ionized ‘bubbles’ at earlier stages of reionization remained uncertain. Here, we present the characterization of three exceptionally distant LAEs at $z \gt 8$, newly discovered by JWST/Near-Infrared Spectrograph in the JADES survey. These three similarly bright ($M_\text{UV} \approx -20 \, \mathrm{mag}$) LAEs exhibit small Ly $\alpha$ velocity offsets from the systemic redshift, $\Delta v_\rm{{Ly\alpha }} \lesssim 200 \, \mathrm{km \, s^{-1}}$, yet span a range of Ly $\alpha$ equivalent widths (15, 31, and $132 \, \mathring{\rm A}$). The former two show moderate Ly $\alpha$ escape fractions ($f_\rm{esc, {Ly\alpha }} \approx 10~{{\rm per\,cent}}$), whereas Ly $\alpha$ escapes remarkably efficiently from the third ($f_\rm{esc, {Ly\alpha }} \approx 72~{{\rm per\,cent}}$), which moreover is very compact (half-light radius of $90 \pm 10 \, \mathrm{pc}$). We find these LAEs are low-mass galaxies dominated by very recent, vigorous bursts of star formation accompanied by strong nebular emission from metal-poor gas. We infer the two LAEs with modest $f_\rm{esc, {Ly\alpha }}$, one of which reveals evidence for ionization by an active galactic nucleus, may have reasonably produced small ionized bubbles preventing complete IGM absorption of Ly $\alpha$. The third, however, requires a $\sim \!3 \, \text{physical Mpc}$ bubble, indicating faint galaxies have contributed significantly. The most distant LAEs thus continue to be powerful observational probes into the earlier stages of reionization.

The cooler past of the intracluster medium in TNG-Cluster

Abstract The intracluster medium (ICM) today is comprised largely of hot gas with clouds of cooler gas of unknown origin and lifespan. We analyze the evolution of cool gas (temperatures ≲ 104.5 K) in the ICM of 352 galaxy clusters from the TNG-Cluster simulations, with present-day mass ∼1014.3 − 15.4 M⊙. We follow the main progenitors of these clusters over the past ∼13 billion years (since z ≲ 7) and find that, according to TNG-Cluster, the cool ICM mass increases with redshift at fixed cluster mass, implying that this cooler past of the ICM is due to more than just halo growth. The cool cluster gas at z ≲ 0.5 is mostly located in and around satellite galaxies, while at z ≳ 2 cool gas can also accrete via filaments from the intergalactic medium. Lower-mass and higher-redshift clusters are more susceptible to cooling. The cool ICM mass correlates with the number of gaseous satellites and inversely with the central supermassive black hole (SMBH) mass. The average number of gaseous satellites decreases since z = 2, correlating with the decline in the cool ICM mass over cosmic time, suggesting a link between the two. Concurrently, kinetic SMBH feedback shifts the ICM temperature distribution, decreasing the cool ICM mass inside-out. At z ≈ 0.5, the predicted Mg ii column densities are in the ballpark of recent observations, where satellites and other halos contribute significantly to the total Mg ii column density. Suggestively, a non-negligible amount of the ICM cool gas forms stars in-situ at early times, reaching ∼102 M⊙ yr−1 and an Hα surface brightness of ∼10−17 erg s−1 cm−2 arcsec−2 at z ≈ 2, detectable with Euclid and JWST.