Research Articles (Physics)

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Euclid preparation: LXXVIII. Full-shape modelling of two-point and three-point correlation functions in real space
(EDP Sciences, 2026) Guidi M.; Veropalumbo A.; Pugno A.; Moresco M.; Sefusatti E.; Porciani C.; Branchini E.; Breton M.-A.; Camacho Quevedo B.; Crocce M.
We investigated the accuracy and range of validity of the perturbative model for the two-point (2PCF) and three-point (3PCF) correlation functions in real space in view of the forthcoming analysis of the Euclid mission spectroscopic sample. We took advantage of clustering measurements from four snapshots of the Flagship I N-body simulations at z = {0.9,1.2,1.5,1.8}, which mimic the expected galaxy population in the ideal case, i.e. in the absence of observational effects such as purity and completeness. For the 3PCF we considered all available triangular configurations given a minimal separation (rmin). We first assessed the model performance by fixing the cosmological parameters and evaluating the goodness of fit provided by the perturbative bias expansion in the joint analysis of the two statistics, finding an overall agreement with the data down to separations of 20 h-1 Mpc. Subsequently, we built on the state-of-the-art analysis and extended it to include the dependence on three cosmological parameters: the amplitude of scalar perturbations (As), the matter density (ωcdm), and the Hubble parameter (h). To achieve this goal, we developed an emulator capable of generating fast and robust modelling predictions for the two summary statistics, which thus enables an efficient sampling of the joint likelihood function. We therefore present the first joint full-shape analysis of the real-space 2PCF and 3PCF, testing the consistency and constraining power of the perturbative model across both probes and assessing its performance in a combined likelihood framework. We explored possible systematic uncertainties induced by the perturbative model at small scales, finding an optimal scale cut of rmin = 30 ha-1 Mpc for the 3PCF when imposing an additional limitation on the nearly isosceles triangular configurations included in the data vector. This work is part of a series of papers in which we validate theoretical models for galaxy clustering measurements in preparation for the Euclid mission.
Results from the investigation of temporal discontinuity in the hydrogen epoch of reionization array data
(Oxford University Press, 2026) Hailemariam, Mekuanint K; Morales, Miguel F; DeBoer, David R; Abdurashidova, Zara; de Lera Acedo, Eloy; Adams, Tyrone; Aguirre, James E; Baartman, Rushelle; Beardsley, Adam P; Bernardi, Gianni; Berkhout, Lindsay M; Billings, Tashalee S; Bowman, Judd D; Byrne, Ruby; Bull, Philip; Burba, Jacob; Cox, Tyler; Carey, Steven; Chen, Kai-Feng; Ghosh, Abhik; Choudhuri, Samir; Dexter, Matt; Dillon, Joshua S; Dynes, Scott; Ely, John; Eksteen, Nico; Fritz, Randall; Furlanetto, Steven R; Gehlot, Bharat Kumar; Razavi-Ghods, Nima; Gorce, Adelie; Gorthi, Deepthi; Halday, Ziyaad; Hazelton, Bryna J; Hewitt, Jacqueline N; Hickish, Jack; Mohamed-Hinds N; Huang, Tian; Jacobs, Daniel C; Josaitis, Alec; Kern, Nicholas S; Kerrigan, Joshua; Kittiwisit, Piyanat; Kolopanis, Matthew; Lanman, Adam; Liu, Adrian; Ma, Yin-Zhe; MacMahon, David H E; Malgas, Cresshim; Malan, Lourence; Malgas, Keith; Marero, Bradley; Martinot, Zachary E; McBride, Lisa; Mesinger, Andrei; Molewa, Mathakane; Nikolic, Bojan; Nuwegeld, Hans; Parsons, Aaron R; Patra, Nipanjana; Pascua, Robert; Plante, Paul La; Qin, Yuxiang; Rath, Eleanor; Riley, Daniel; Robnett, James; Rosie, Kathryn; Santos, Mario G; Gale-Sides, Kingsley; Sims, Peter; Singh, Saurabh; Storer, Dara; Swarts, Hilton; Tan, Jianrong; Ewall-Wice, Aaron; Wilensky, Michael J; Williams, Peter K G; van Wyngaarden, Pieter; Zheng, Haoxuan
We report systematic issues commonly observed in the Hydrogen Epoch of Reionization Array observations that cause abrupt changes in power over time, resulting in temporal discontinuities. To identify these effects, we applied the Temporal Discontinuity Index and Spectral Discontinuity Index metrics, which complement existing diagnostic tools by detecting discontinuities and revealing their potential relationships to bandpass and power-related issues. Analysis of 30 data sets, each corresponding to a single observing night, shows that such systematics appear consistently in many antennas and across multiple nights. Based on these metrics, we identify three main types of discontinuity-related issues: periodic broad-band discontinuities linked to Inter-Integrated Circuit (I2C) polling, broad-band discontinuities associated with degraded post-amplifier modules (PAMs), and sudden power changes related to the digital backend of the antenna system. The second type, associated with degraded PAMs, occurs less frequently within a single night compared to the periodic polling effect, though both are broadband. The third type affects the largest number of antennas and is most prevalent in the H6C data. The width of the discontinuities related to the digital backend corresponds to the frequency range handled by a single correlator box, scaled by the number of boxes involved. Although 30 data sets were examined, this paper presents a focused analysis of four representative nights to highlight the main discontinuity issues. We also present correlations between flagging due to discontinuities and flagging caused by other failure modes to investigate how these issues are interrelated.
MIGHTEE: the dark matter haloes, duty cycle, and mechanical feedback from radio-AGN up to z ∼ 2.5
(Oxford University Press, 2026) Jarvis, Matthew; Whittam, Imogen H
Radio-AGNs (active galactic nuclei) are observed to be more strongly clustered than non-active galaxies, though it is unclear whether this is simply due to their preference for massive host galaxies, or if they reside in distinct environments beyond this mass dependence. Using data from three fields covered by the MIGHTEE survey, we measure the angular two-point cross-correlation functions with a large, stellar mass-limited population of near-infrared selected galaxies, overcoming limitations of previous single-deep-field studies. By fitting halo occupation distribution models, we infer the galaxy bias parameters, b, for radio-AGN in three redshift ranges with median redshifts of (Formula presented), (Formula presented), and (Formula presented), finding (Formula presented), (Formula presented), and (Formula presented), respectively. The typical dark matter halo mass decreases with increasing redshift: (Formula presented), (Formula presented), and (Formula presented), which we attribute to the increased abundance of cold gas required to fuel AGN activity at earlier times. The AGN duty cycle is determined to be (Formula presented) per cent, and we estimate that the total energy radiated by radio-jets over (Formula presented) is (Formula presented) per halo, which is sufficient to account for the observed excess heating of gas beyond that of gravitational collapse. Comparing the typical dark matter halo masses to the values obtained for the control sample, we find that the halo masses of radio-AGN are (Formula presented), (Formula presented), and (Formula presented) times greater than those of the stellar mass- and redshift-matched galaxies. This difference could arise because AGN feedback suppresses stellar mass growth while leaving halo mass unchanged, or because radio-AGN preferentially reside in earlier forming haloes which are more strongly clustered.
Fathomer survey. Iii. Preliminary higalaxy identification results
(American Astronomical Society, 2026) Shu, Shuanghao; Li, Yichao; Yang, Wenxiu; Wang, Jiaxin; Hu, Wenkai; Deng, Furen
We present the H i galaxy observation results of FATHOMER, a pilot drift scan survey by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The survey comprises 28 hr of observations over seven nights in 2021, covering a 60 deg2 sky area in the frequency range 1.05–1.45 GHz. The H i galaxies are identified using both a matched-filtering algorithm and the SoFiA source-finding pipeline, which yield consistent detections. We derive the velocity width (W50), flux density, and Hi mass for detected galaxies. A total of 702 galaxies are identified with H i mass above 106.2 M⊙, signal-to-noise ratio greater than 5, and redshift z < 0.09. Among these, 331 are previously known from the ALFALFA survey. Of the newly detected sources, 9 have spectroscopic confirmation from the Sloan Digital Sky Survey (SDSS), 285 are matched to SDSS or DESI photometric data, and 77 lack optical counterparts–possible candidates for dark or faint galaxies. Comparison with ALFALFA shows that FAST enables the detection of galaxies at higher redshifts and with lower Hi fluxes, despite the radio frequency interference (RFI) and partial data masking. A preliminary Hi mass function analysis reveals a higher characteristic mass and steeper low-mass slope than ALFALFA, indicating FAST’s enhanced sensitivity to massive and distant H i systems. These results demonstrate FAST’s strong potential for future deep H i surveys and highlight the importance of improved RFI mitigation and completeness correction.
Covariant cosmography in the presence of local structures: comparing exact solutions and perturbation theory
(Institute of Physics, 2026) Sarma, Maharshi; Marinoni, Christia; Kalbouneh, Bashee; Clarkson, Chris; Maartens, Roy
Recent observational evidence of axially symmetric anisotropies in the local cosmic expansion rate motivates an investigation of whether they can be accounted for within the Lemaître– Tolman-Bondi (LTB) framework with an off-center observer. Within this setting, we compute the exact relativistic luminosity distance via the Sachs equation and compare it with the approximate expression obtained from the covariant cosmographic approach (including Hubble, deceleration, jerk and curvature parameters). This comparison allows us to identify the regimes in which the covariant cosmographic method remains reliable. In addition, we compare the LTB relativistic distance for small inhomogeneities with the corresponding result derived from linear perturbation theory (LPT) in the standard cosmological model. This analysis establishes a precise correspondence between the LTB and LPT approaches, offering a consistent dictionary for the interpretation of the observed anisotropies of the large-scale gravitational field. We test luminosity distance reconstructions in a spherically symmetric overdensity with an off-center observer. For moderate central density contrasts (δc ≲ 1), LPT reproduces the exact distance within 10% for observers inside the typical size of the structure. However, Covariant Cosmography (CC) extends this regime of validity upto δc ≲ 2.5. At larger radii, the situation reverses: for observers at three times the characteristic size, LPT remains accurate up to δc ≲ 3, while CC already exceeds 10% error for δc ≳ 1.5. At sufficiently large distances from the structure, both methods converge to the exact solution. Thus, CC is essential for accurate distance estimates near dense regions, while LPT remains reliable at larger separations. This analysis will be instrumental in interpreting expansion-rate anisotropies, facilitating investigations of the local Universe beyond the FLRW framework with a fully non-perturbative metric approach.
Prospects for measuring the doppler magnification dipole with LSST and DESI
(Oxford University Press, 2026) Clarkson, Chris; Bull, Philip; Ye, Isabelle; Guandalin, Caroline; Nasirudin, Ainulnabilah
We forecast the detectability of the Doppler magnification dipole with a joint analysis of galaxy spectroscopic redshifts and size measurements. The Doppler magnification arises from an apparent size variation caused by galaxies’ peculiar velocities when mapping them from redshift space to real space. This phenomenon is the dominant contribution to the convergence at low redshifts ((Formula presented) 0.5). A practical observational strategy is to cross-correlate a galaxy number count tracer, e.g. from the Dark Energy Spectroscopic Instrument (DESI) Bright Galaxy Survey, with the convergence field reconstructed from galaxy size measurements obtained by the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST). To assess the achievable precision of galaxy size measurements, we simulate LSST Y1-quality galaxy images with Galsim and measure them with the Galight profile fitting package. Our investigations, based on galaxy populations from LSST’s synthetic galaxy catalogue cosmoDC2, show that the variance due to intrinsic galaxy size variation dominates over size measurement errors as expected, but may be lower than previous studies have suggested. Under our analysis assumptions, the Doppler magnification dipole would be detectable with a signal-to-noise ratio (Formula presented) in multiple redshift bins between (Formula presented) with DESI spectroscopic redshifts and LSST imaging.
Collectivity of the deformed structure in 96zr from complementary coulomb-excitation and β-decay measurements
(Elsevier B.V., 2026-06) Maqungo L.; Triambak S.; Garrett P.E.; Zielińska M.; Rocchini M.
The B(E2;22+→01+) value in 96Zr was determined from a Coulomb-excitation measurement with 12C and 16O beams performed at the Maier-Leibnitz Laboratory with a Q3D magnetic spectrograph. High-precision γ -ray branching ratios in the decay of the 22+ state in 96Zr, and a new value of the 22+→21+ multipole mixing ratio, were obtained from a complementary β -decay experiment, performed using the GRIFFIN spectrometer at the TRIUMF-ISAC facility. Combining these results yields B(E2;22+→02+)=38.9(57) W.u. which is in agreement with the previous measurement, but considerably more precise. The observed differences between the properties of structures built on the 02+ states in 94Zr and 96Zr are discussed in the context of possible triple shape coexistence in Zr nuclei.
LXXI. Simulations and nonlinearities beyond ΛCDM. 3. Constraints on f(R) models from the photometric primary probes
(EDP Sciences, 2025) Karagiannis Dionysis; Koyama K; Pamuk S; Casas S
We study the constraint on f(R) gravity that can be obtained by photometric primary probes of the Euclid mission. Our focus is the dependence of the constraint on the theoretical modelling of the nonlinear matter power spectrum. In the Hu–Sawicki f(R) gravity model, we consider four different predictions for the ratio between the power spectrum in f(R) and that in Λ cold dark matter (ΛCDM): a fitting formula, the halo model reaction approach, ReACT, and two emulators based on dark matter only N-body simulations, FORGE and e-Mantis. These predictions are added to the MontePython implementation to predict the angular power spectra for weak lensing (WL), photometric galaxy clustering, and their cross-correlation. By running Markov chain Monte Carlo, we compare constraints on parameters and investigate the bias of the recovered f(R) parameter if the data are created by a different model. For the pessimistic setting of WL, one-dimensional bias for the f(R) parameter, log10|fR0|, is found to be 0.5σ when FORGE is used to create the synthetic data with log10|fR0| = −5.301 and fitted by e-Mantis. The impact of baryonic physics on WL is studied by using a baryonification emulator, BCemu. For the optimistic setting, the f(R) parameter and two main baryonic parameters are well constrained despite the degeneracies among these parameters. However, the difference in the nonlinear dark matter prediction can be compensated for the adjustment of baryonic parameters, and the one-dimensional marginalised constraint on log10|fR0| is biased. This bias can be avoided in the pessimistic setting at the expense of weaker constraints. For the pessimistic setting, using the ΛCDM synthetic data for WL, we obtain the prior-independent upper limit of log10|fR0| < −5.6. Finally, we implement a method to include theoretical errors to avoid the bias due to inaccuracies in the nonlinear matter power spectrum prediction.
Exploring one-point statistics in HERA phase I data: effects of foregrounds and systematics on measuring one-point statistics
(American Astronomical Society, 2026) Bull, Phillip; Kim, Honggeun; Hewitt, Jacqueline N.
The epoch of reionization (EoR) marks a pivotal phase in cosmic evolution, transitioning the intergalactic medium (IGM) from mostly neutral to ionized. Studying this transition offers key insights into the formation of the first luminous sources. A primary observable from the EoR is the redshifted 21 cm line emission, originating from hyperfine splitting in ground-state neutral hydrogen. Radio interferometers, designed to detect these faint signals, are crucial for characterizing the EoR. In recent years, various radio interferometers have undertaken extensive efforts to probe the power spectrum of 21 cm fluctuations during the EoR, leading to several upper limits. These include the Giant Meter Wave Radio Telescope (GMRT; G. Paciga et al. 2013), the Murchison Widefield Array (MWA; S. J. Tingay et al. 2013; J. S. Dillon et al. 2014; A. P. Beardsley et al. 2016; N. Barry et al. 2019; C. M. Trott et al. 2020), the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER; A. R. Parsons et al. 2010; C. Cheng et al. 2018; M. Kolopanis et al. 2019), the Low Frequency Array (LOFAR; van Haarlem et al. 2013; A. H. Patil et al. 2017; F. G. Mertens et al. 2020; R. Ghara et al. 2025), and the Hydrogen Epoch of Reionization Array (HERA; J. S. Dillon & A. R. Parsons 2016; D. R. DeBoer et al. 2017; L. M. Berkhout et al. 2024). More recently, The HERA Collaboration et al. (2022a, hereafter H22a) and The HERA Collaboration et al. (2023, hereafter H23) reported upper limits on the 21 cm power spectrum. The HERA Collaboration et al. (2022b, hereafter H22b) and H23 explored the astrophysical parameter space, using these limits to constrain IGM X-ray heating and disfavor inefficient heating by z ∼ 8.
Euclid preparation: LXXXIII. the impact of redshift interlopers on the two-point correlation function analysis
(EDP Sciences, 2026) Karagiannis, Dionysics; Risso I.; Veropalumbo A.
Context. The Euclid galaxy survey is designed to measure the spectroscopic redshift of emission-line galaxies (ELGs) by identifying the Hα emission line in their slitless spectra. The efficacy of this approach crucially depends on the signal-to-noise ratio (S/N) of the line, as sometimes noise fluctuations in the spectrum continuum can be misidentified as Hα. In addition, other genuine strong emission lines can be mistaken for Hα, depending on the redshift of the source. Both effects lead to ambiguities in the redshift measurement that can result in catastrophic redshift errors and the inclusion of interloper galaxies in the sample. Aims. This paper forecasts the impact on the galaxy clustering analysis of the expected redshift errors in the Euclid spectroscopic sample. Specifically, it investigates the effect of the redshift interloper contamination on the galaxy two-point correlation function (2PCF) and, in turn, on the inferred growth rate of structure f8 and Alcock Paczynski (AP) parameters α and α. Methods. This work is based on the analysis of 1000 synthetic spectroscopic catalogues, the EuclidLargeMocks, which mimic the area and selection function of the Euclid Data Release 1 (DR1) sample. We estimated the 2PCF of contaminated catalogues and separated the different contributions, particularly those coming from galaxies with correctly measured redshift and from contaminants. We explored different models of increasing complexity to describe the measured 2PCF at a fixed cosmology, with the aim of identifying the most efficient model to reproduce the data. Finally, we performed a cosmological inference and evaluated the systematic error on the inferred f8, α, and α values associated with different models. Results. Our results demonstrate that a minimal modelling approach, which only accounts for an attenuation of the clustering signal regardless of the type of contaminants, is sufficient to recover the correct values of f8, α, and α at DR1. The accuracy and precision of the estimated AP parameters are largely insensitive to the presence of interlopers. The adoption of a minimal modelling induces a 1% 3% systematic error on the growth rate of structure estimation, depending on the considered redshift. However, this error remains smaller than the statistical error expected for the Euclid DR1 analysis.
Atomic hydrogen reservoirs in quiescent galaxies at z = 0.4
(EDP Sciences, 2025) Bianchetti A.; Elson Ed; Vaccari Mattia
Context. Based on local Universe observations, quiescent galaxies (QGs) host lower or negligible HI compared to star-forming galaxies (SFGs), but no constraints have been derived to date at higher redshift (z > 0.1). Understanding whether QGs can retain significant HI reservoirs at higher z is crucial for refining quenching and gas accretion models and for constraining overall star formation efficiency at different epochs. Aims. We aim to probe HI in candidate QGs at intermediate redshifts ({z} ≈ 0.36) and to understand whether a class of QGs exists that retains consistent HI reservoir, as well as which parameters (dust content, stellar mass, Dn4000, morphology, and environment) effectively capture HI-rich QGs. Methods. We performed 21-cm spectral line stacking on MIGHTEE-HI data at {z} = 0.36, targeting two different samples of QGs, defined by means of a color-selection criterion and a spectroscopic criterion based on Dn4000, respectively. We also performed stacking on subsamples of the spectroscopically selected quiescent sample to investigate the correlation between the HI content and other galaxy properties. Results. We find that QGs with an IR counterpart (i.e., dusty galaxies) host a substantial HI content, on average only 40% lower than that of SFGs. In contrast, color-selected QGs still retain HI, but at levels lower than those of SFGs by a factor of ∼3. Among dusty objects, we find that morphology has a mild impact on the atomic gas content, with spirals hosting approximately 15-30% more HI than spheroids. Environmental effects are also present: galaxies in low-density regions are richer in HI than those in high-density regions, by approximately 30% for spirals and 60% for spheroids. We suggest that, in general, HI content is influenced by several factors, including slow quenching mechanisms and interstellar medium (ISM) enrichment processes. Also, QGs - and especially dusty systems - seem to yield HI more consistently than in the local Universe.
Euclid: searches for strong gravitational lenses using convolutional neural nets in early release observations of the perseus field
(EDP Sciences, 2025) Pearce-Casey R.; Vaccari, M; Nagam B.C.
The Euclid Wide Survey (EWS) is predicted to find approximately 170 000 galaxy-galaxy strong lenses from its lifetime observation of 14 000 deg2 of the sky. Detecting this many lenses by visual inspection with professional astronomers and citizen scientists alone is infeasible. As a result, machine learning algorithms, particularly convolutional neural networks (CNNs), have been used as an automated method of detecting strong lenses, and have proven fruitful in finding galaxy-galaxy strong lens candidates, such that the usage of CNNs in lens identification has increased. We identify the major challenge to be the automatic detection of galaxy-galaxy strong lenses while simultaneously maintaining a low false positive rate, thus producing a pure and complete sample of strong lens candidates from Euclid with a limited need for visual inspection. One aim of this research is to have a quantified starting point on the achieved purity and completeness with our current version of CNN-based detection pipelines for the VIS images of EWS. This work is vital in preparing our CNN-based detection pipelines to be able to produce a pure sample of the >100 000 strong gravitational lensing systems widely predicted for Euclid. We select all sources with VIS IE < 23 mag from the Euclid Early Release Observation imaging of the Perseus field. We apply a range of CNN architectures to detect strong lenses in these cutouts. All our networks perform extremely well on simulated data sets and their respective validation sets. However, when applied to real Euclid imaging, the highest lens purity is just ∼11%. Among all our networks, the false positives are typically identifiable by human volunteers as, for example, spiral galaxies, multiple sources, and artifacts, implying that improvements are still possible, perhaps via a second, more interpretable lens selection filtering stage. There is currently no alternative to human classification of CNN-selected lens candidates. Given the expected ∼105 lensing systems in Euclid, this implies 106 objects for human classification, which while very large is not in principle intractable and not without precedent.
Multipoles of the galaxy bispectrum on a light cone: wide-separation and relativistic corrections
(Institute of Physics, 2025) Addis, Chris; Clarkson, Chris; Guandalin, Caroline
The galaxy bispectrum provides access to correlations among different scales that cannot be captured by the power spectrum alone, and with the Stage-IV galaxy surveys it enables the possibility of detecting both primordial non-Gaussianity (PNG) and general relativistic effects. Accounting for wide-separation corrections, which arise from the loss of symmetry in the correlation of widely separated points on the past light cone, is essential for their accurate modelling and detection. These corrections can be included perturbatively to the standard bispectrum and we compute them analytically for a generalised line of sight, including the radial evolution contribution to the bispectrum for the first time. We show that the first-order corrections entering the odd multipoles with respect to the line of sight are large, up to 10% of the bispectrum monopole, and need to be included when considering the leading-order relativistic effects that could be detectable with surveys like DESI and Euclid. The second-order wide-separation and relativistic contributions, including their mixing terms, enter into the even multipoles and therefore have implications for analysis of PNG and we show, for the local type, they can mimic fNL of order 10 in the squeezed limit. We present full analytic expressions for all these contributions to the local bispectrum and its multipoles which are implemented in a new publicly available Python package CosmoWAP.
The JWST EXCELS Surv ey: gas-phase metallicity ev olution at 2 < z < 8
(Oxford University Press, 2026) R. Davé; T. M. Stanton; F. Cullen
The metallicities of galaxies are intrinsically sensitive to the over- ar ching pr ocesses governing g alaxy evolution. Inflows of metal- poor gas provide fuel for star formation, stars produce metals via nucleosynthesis over their lifetimes, and supernova-driven out- flows remove metal-enriched gas from galaxies (i.e. the baryon cycle; B. M. Tinsley 1980 ; K. Finlator & R. Davé2008 ; J. Tumlin- son, M. S. Peeples & J. K. Werk 2017 ). In combination with es- timat es of st ellar masses and star-formation rat es (SFRs), metal- licity measurements can be considered a fundamental tracer of the evolution and gr owth of g alaxies acr oss cosmic time. Since the launch of the James Webb Space Telescope ( JWST ), and in particular thanks to the unprecedented sensitivity of the Near- Infrar ed Spectr ograph (NIRSpec, P. Jakobsen et al. 2022 ), there has been a significant advance in the capability of measuring accurate galaxy metallicities at high r edshift ( z 2 ). We ar e now in a position to trace chemical imprints of the cosmic baryon cycle from the epoch of reionization to the local Universe.
Toward reconciling reionization with jwst: the role of bright galaxies and strong feedback
(American Astronomical Society, 2026) Bera, Ankita; Hassan, Sultan; Feldmann, Robert; Dav́e, Romeel; Finlator, Kristian M.
The elevated UV luminosity functions (UVLFs) from recent James Webb Space Telescope (JWST) observations have challenged the viability of existing theoretical models. To address this, we use a semianalytical framework—which couples a physically motivated source model derived from radiative transfer hydrodynamic simulations of reionization with a Markov Chain Monte Carlo sampler—to perform a joint calibration to JWST galaxy surveys (UVLF, ϕUV, and UV luminosity density, ρUV) and reionization-era observables (ionizing emissivity, (Formula presented) Ṅion, neutral hydrogen fraction, xHI, and Thomson optical depth, τ). We find that models with weak feedback and a higher contribution from faint galaxies reproduce the reionization observables but struggle to match the elevated JWST UVLF at z > 9. In contrast, models with stronger feedback (i.e., rapid redshift evolution) and a higher contribution from bright galaxies successfully reproduce JWST UVLF at z ≥ 10 but overestimate the bright end at z < 9. The strong-feedback model constrained by the JWST UVLF predicts a more gradual and extended reionization history, as opposed to the sudden reionization seen in the weak-feedback models. This extended nature of reionization (z ∼ 16–6) yields an optical depth consistent (at 2σ) with the cosmic microwave background (CMB) constraint, thereby alleviating the photon budget crisis. In both scenarios, reionization is complete by z ∼ 6, consistent with current data. Our analysis highlights the importance of accurately modeling feedback and ionizing emissivities from different source populations during the first billion years after the Big Bang.
Single-particle neutron states in 199Hg populated in the 200Hg(d,t) 199Hg reaction
(American Physical Society, 2026) K.Yanase; G.C. Ball; A.Diaz Varela
Single-particle states in 199Hg have been studied with the 200Hg(d,t)199Hg reaction using 22-MeV deuterons. The reaction products were momentum analyzed using a Q3D magnetic spectrograph, and a position-sensitive cathode-strip detector located at the focal plane recorded the particle spectra. Cross sections for the population of individual states up to approximately 3-MeV excitation energy were determined, and angular distributions have been constructed. In total, 93 levels were observed, including and 52 previously unobserved levels, and spin-parity assignments made for 16 previously established levels. The results were compared with large-scale shell-model calculations that reproduce well the spectroscopic strengths for levels at low excitation energy, and the trends in the cumulative strength to high excitation energy. ©2026 American Physical Society.
Uniform rolling: an LSST observing cadence offering sufficient survey uniformity for comprehensive cosmological analysis
(American Astronomical Society, 2026) Lochner, Michelle; Leistedt, Boris; Becker, Matthew
The Legacy Survey of Space and Time (LSST) that will be carried out by the NSF-DOE Vera C. Rubin Observatory promises to be the defining survey of the next decade for both static and time-domain science. Maximizing the LSST’s scientific output requires a nontrivial survey strategy (i.e., the sequence of observations in space, time, and passband). For time-domain science, the most promising strategy to date is a rolling survey strategy, whereby alternating subsets of the full LSST area are observed at a higher-than-nominal rate. Focusing on static science (galaxy clustering and weak lensing), we study how time-domain-optimized rolling strategies affect the depth uniformity at intermediate survey years and present new metrics directly connecting depth uniformity with science return. We characterize the amount of survey area at high risk of being lost in static-science analyses of a rolling LSST data set due to insufficient survey uniformity. At intermediate data releases, nearly half of the survey could be lost for static science, decreasing the dark energy figure of merit by 40%. We describe additional metrics focused on key analysis tasks, such as photometric redshifts and galaxy clustering. Finally, we propose a new strategy that returns the survey to uniformity at key release years, enabling use of the full area and restoring our metrics to the values they would have in a nonrolling cadence—without losing time domain data relative to a rolling survey with the same number of rolling cycles. These new “uniform rolling” strategies have been incorporated into the LSST baseline strategy.
One sightline, many systems: a flash discovery of H I towards scintillating quasar PKS 0405-385
(Cambridge University Press, 2026) Kerrison, Emily F.; Yoon, Hyein; Sadler, Elaine M.; Kang, Yijung; Edwards, Philip G.; Tuntsov, Artem V.; Pritchard, Joshua; Moss, Vanessa A.; Mahony, Elizabeth K.; Bignall, Hayley E.; Aditya, J. N.H.S.; Allison, James R.; Curran, Stephen J.; Ekers, Ronald D.; Glowacki, Marcin; Stevens, Jamie B.; Su, Renzhi; Whiting, Matthew Thomas
We report the discovery of an intervening 21 cm absorption line at z = 0.882 towards the z = 1.284 quasar PKS 0405-385, identified in the First Large Absorption Survey in H I (FLASH). This quasar once displayed the most rapid known intraday variability at radio frequencies, from which it earned the title of ‘the smallest radio quasar’. Although its size was revised upwards soon after based on updated scattering theory, PKS 0405-385 remains an important probe of Galactic plasma, and now also of intervening gas discovered through H I absorption. We present new long-slit spectroscopy spanning both PKS 0405-385 and the candidate host of the intervening H I gas. We identify Mg II and Fe II absorption lines in this spectrum consistent with the redshift of the intervening H I, as well as two additional, independent metal-line systems at z = 0.907 and z = 0.966, but we cannot accurately pinpoint the host(s) of this intervening gas in current data. We revisit the radio variability of PKS 0405-385 in light of advances in scintillation theory, as well as extended monitoring with the Australia Telescope Compact Array and the Australian SKA Pathfinder, and find a revised linear size ≥ 0.3 pc, but no new evidence of repeating intraday variability.
Mightee-H i: the star-forming properties of H i-selected galaxies
(Oxford University Press, 2026) Tudorache, Madalina N.; Jarvis, Matthew J.; Ponomareva, Anastasia A.; Heywood, Ian; Maddox, Natasha; Glowacki, Marcin; Frank, Bradley S.; Baes, Maarten; Dav́e, Romeel; Jung, Seoyoung Lyla; Maksymowicz-Maciata, Michalina; Pan, Hengxing; Spekkens, Kristine
The interplay between atomic gas and the star formation history (SFH) of a galaxy are intrinsically linked, and we need to decouple these dependencies to understand their role in galaxy formation and evolution. In this paper, we analyse the SFH of 203 galaxies from the MIGHTEE-H i Survey Early Science Release data, cross-matched to with multiwavelength photometry across the COSMOS and XMM-LSS fields. We focus on the relationships between H i properties and star formation, with a sample which primarily traces gas-rich, star-forming systems at low redshift, extending to low stellar masses and probing regimes that are difficult to access with optically selected samples. A strong correlation emerges between a galaxy’s H i-to-stellar mass ratio and the time of formation, alongside an inverse correlation between stellar mass and time of formation, regardless of the inferred SFH. Additionally, galaxies with lower stellar masses and higher H i-to-stellar mass ratios exhibit longer gas depletion times compared to more massive galaxies, which appear to have depleted their gas and formed stars more efficiently. This suggests that smaller, gas-rich galaxies have higher depletion times due to shallower potential wells and less efficient star formation. Within this H i-selected sample, the efficiency of star formation is regulated primarily by stellar mass and gas fraction, with low-mass galaxies retaining extended atomic reservoirs due to inefficient conversion of H i into stars.
Phantom crossing or dark interaction?
(Institute of Physics, 2026) Guedezounme, Sêcloka L; Dinda, Bikash R; Maartens, Roy
Recent results from DESI BAO measurements, together with Planck CMB and Pantheon+ data, suggest that there may be a 'phantom' phase (wde< -1) in the expansion of the Universe. This inference follows when the w0,wa parametrization for the dark energy equation of state wdeis used to fit the data. Since phantom dark energy in general relativity is unphysical, we investigate the possibility that the phantom behaviour is not intrinsic, but effective — due to a non-gravitational interaction between dark matter and non-phantom dark energy. To this end, we assume a physically motivated thawing quintessence-like form of the intrinsic dark energy equation of state wde. Then we use a w0,wa model for theeffectiveequation of state of dark energy. We find that the data favours a phantom crossing for the effective dark energy, but only at low significance. The intrinsic equation of state of dark energy is non-phantom, without imposing any non-phantom priors. A nonzero interaction is favoured at more than 3σatz∼ 0.3. The energy flows from dark matter to dark energy at early times and reverses at later times.

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