Research Articles (Physics)

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COSMOS spectroscopic redshift compilation (First Data Release): 488,000 redshifts encompassing two decades of spectroscopy
(American Astronomical Society, 2026) Vaccari, Mattia; Khostovan, Ali Ahmad; Kartaltepe, Jeyhan S.
We present the COSMOS Spectroscopic Redshift Compilation encompassing ∼20 yr of spectroscopic redshifts within a 10 deg2 area centered on the 2 deg2 COSMOS legacy field. This compilation contains 487,666 redshifts of 266,284 unique objects from 138 individual programs up to z ∼ 8 with median stellar mass ∼108.4-1010 M⊙ (redshift dependent). Rest-frame NUVrJ colors and star formation rate-stellar mass correlations show that the compilation primarily contains low-to-intermediate-mass star-forming and massive, quiescent galaxies at z < 1.25 and mostly low-mass bursty star-forming galaxies at z > 2. Sources in the compilation cover a diverse range of environments, including protoclusters such as “Hyperion.” The full compilation is 50% spectroscopically complete by i ∼ 23.4 mag and Ks ∼ 21.6 mag; however, this is redshift dependent. Spatially, the compilation is >50% (>30%) complete within the central (outer) region limited to i < 24 mag and Ks < 22.5 mag, separately. We demonstrate how the compilation can be used to validate photometric redshifts and investigate calibration metrics. By training self-organizing maps on COSMOS2020/Classic and projecting the compilation onto it, we find key subpopulations currently lacking spectroscopic coverage, including z < 1 intermediate-mass quiescent and low-/intermediate-mass bursty star-forming galaxies, z ∼ 2 massive quiescent galaxies, and z > 3 massive star-forming galaxies. This highlights how combining self-organizing maps with our compilation can provide guidance for future spectroscopic observations to get a complete spectroscopic view of galaxy populations. Lastly, the compilation will undergo periodic data releases incorporating new spectroscopic redshifts and providing a lasting legacy resource for the community.
Subshell gaps and onsets of collectivity from proton and neutron pairing gap correlations
(Elsevier Inc., 2025) Orce, José Nicolás
Throughout the nuclear chart, particle-hole correlations give rise to giant resonances and, together with the proton–neutron interaction, deformation and rotational bands. In order to shed light on many-body correlations in open-shell nuclei, I explore macroscopic properties that could manifest from the collective behaviour of protons and neutrons. Intuitively, the correlation of proton and neutron Cooper pairs can be inferred from the respective pairing gaps, that can precisely be extracted from the AME 2020 atomic mass evaluation through odd-even atomic mass differences. This work shows that the combination of large and close-lying proton and neutron pairing gaps is sensitive to onsets of collectivity and subshell gaps in superfluid nuclei, away from major shell closures. Trends of reduced transition probabilities or B(E2) values — which describe the collective overlap between the wave functions of initial and final nuclear states — are revealed in overall agreement with data. Specially interesting is the peak of collectivity in the tin isotopes at 110Sn, instead of at midshell, as expected by large-scale shell-model calculations; a situation that has astounded the nuclear physics community for quite some time.
The polarisation sky survey of the universe’s magnetism (POSSUM): science goals and survey description
(Cambridge University Press, 2025) Gaensler, B.M; McClure-Griffiths, N.M; McClure-Griffiths, N.M; Anderson, C.S; Van Eck, C.L; West, J.L; Thomson, A.J.M; Leahy, J.P; Rudnick, L; Ma, Y.K; Akahori, Takuya; Gürkan, G; Landecker, T.L; Mao, S.A; O’Sullivan, S.P; Raja, W; Sun, X; Vernstrom, T; Baidoo, Lerato; Carretti, Ettore; Taylor, A.R; Willis, A.G; Osinga, Erik; Livingston, J.D; Alexander, E.L; Alonso-López, David; Amaral, A.D; An, T; Bracco, Andrea; Bradbury, S; Brüggen, Marcus; Eswaraiah, Chakali; Enßlin, Torsten; Galvin, T.J; Haverkorn, Marijke; Hopkins, A.M; Hutschenreuter, Sebastian; Ideguchi, Shinsuke; Jaswanth, S; Jung, S. Lyla; Kaczmarek, J.F; Kothes, Roland; Lazarević, Sanja; Leahy, Denis; Loi, Francesca; Marvil, Joshua R; Norris, Ray; Pandhi, Ayush; Price, Jason M; Riseley, C.J; Ryder, P; Seta, Amit; Shaw, Vasundhara; Shen, A.X; Sobey, C; Stil, J; Stuardi, Chiara; Upasana, Gupta; Vanderwoude, Shannon; Velović, Velibor
The Australian SKA Pathfinder (ASKAP) offers powerful new capabilities for studying the polarised and magnetised Universe at radio wavelengths. In this paper, we introduce the Polarisation Sky Survey of the Universe’s Magnetism (POSSUM), a groundbreaking survey with three primary objectives: (1) to create a comprehensive Faraday rotation measure (RM) grid of up to one million compact extragalactic sources across the southern ∼ 50% of the sky (20,630 deg2); (2) to map the intrinsic polarisation and RM properties of a wide range of discrete extragalactic and Galactic objects over the same area; and (3) to contribute interferometric data with excellent surface brightness sensitivity, which can be combined with single-dish data to study the diffuse Galactic interstellar medium. Observations for the full POSSUM survey commenced in May 2023 and are expected to conclude by mid-2028. POSSUM will achieve an RM grid density of around 30–50 RMs per square degree with a median measurement uncertainty of ∼1 rad m−2. The survey operates primarily over a frequency range of 800–1088 MHz, with an angular resolution of 20” and a typical RMS sensitivity in Stokes Q or U of 18 μJy beam−1. Additionally, the survey will be supplemented by similar observations covering 1296–1440 MHz over 38% of the sky. POSSUM will enable the discovery and detailed investigation of magnetised phenomena in a wide range of cosmic environments, including the intergalactic medium and cosmic web, galaxy clusters and groups, active galactic nuclei and radio galaxies, the Magellanic System and other nearby galaxies, galaxy halos and the circumgalactic medium, and the magnetic structure of the Milky Way across a very wide range of scales, as well as the interplay between these components.
Hyenas: X-ray bubbles and cavities in the intragroup medium
(Oxford University Press, 2025) Jennings, Fred J; Babul, Arif; Davé, Romeel; Cui, Weiguang; Rennehan, Douglas
We investigate the role of the simba feedback model on the structure of the intragroup medium (IGrM) in the new hyenas suite of cutting-edge cosmological zoom-in simulations. Using 34 high-resolution zooms of haloes spanning from 1013-1014 M⊙ at z=0.286, we follow haloes for 700 Myr, over several major active galactic nuclei (AGNs) jet feedback events. We use the moxha package to generate mock Chandra X-ray observations, as well as predictive mocks for the upcoming LEM mission, identifying many feedback-generated features such as cavities, shock-fronts, and hot-spots, closely mimicking real observations. Our sample comprises 105 snapshots with identified cavities, 50 with single bubbles, and 55 with two, and spans three orders of magnitude in observed cavity enthalpies, from 1041-1044 erg s-1. Comparing semimajor axis length, midpoint radius, and eccentricity to a matched sample of observations, we find good agreement in cavity dimensions with real catalogues. We estimate cavity power from our mock maps following observational procedures, showing that this is typically more than enough to offset halo cooling, particularly in low-mass haloes, where we match the observed excess in energy relative to cooling. Bubble enthalpy as measured with the usual midpoint pressure typically exceeds the energy released by the most recent jet event, hinting that the mechanical work is done predominantly at a lower pressure against the IGrM. We demonstrate for the first time that X-ray cavities are observable in a modern large-scale simulation suite and discuss the use of realistic cavity mock observations as new halo-scale constraints on feedback models in cosmological simulations.
Search for β-delayed fission of 178Aug,m and an updated systematics in the region of neutron-deficient nuclei
(American Physical Society, 2026) Andel, B; Andreyev, A N; Bara, S; Cocolios, T E; Cubiss, J G; Page, C; Van, Duppen P; Algora, A; Antalic, S; Athanasakis-Kaklamanakis, M; Au, M; Bark, R A; Barzakh, A; Borge, MJG; Camaiani, A; Chrysalidis, K; Costache, C; De Witte, H; Fedorov, DV; Fedosseev, V N; Fraile, L.M; Fynbo H.O.U; Grzywacz, R; Heinke, R; Johnson, J; Jones, P.M; Judson, D.S; Melcom, D.T. Kattikat; Khan, M.M; Klimo, J; Korgul, A; Labiche, M; Lica, R; Madurga, M; Marginean, N; Marini, P; Marsh, B.A; Mihai, C; Mišt, J; Molkanov, P.L; Nácher, E; Neacsu, C; Orce, Nico J; Page, R.D; Pakarinen, J; Papadakis, P; Pascu, S; Perea, A; Piersa-Siłkowska, M; Podolyák, Z; Schmitt, C; Seliverstov, M.D; Sitarčík, A; Stamati, E; Stoica, A; Stott, A; Stryjczyk, M; Tengblad, O; Tsekhanovich, I; Turturica, A; Udías J.M; Warr, N; Youssef, A
A search for a β-delayed fission (βDF) decay branch of isomerically pure samples of 178Aug and 178Aum was performed at the ISOLDE-CERN facility. Two complementary detection systems capable of registering α decays and fission fragments, the ISOLDE Decay Station and the ASET (Alpha SETup), were used. Despite very high statistics of produced 178Au nuclei, no fission fragments were detected. Upper limits of βDF probabilities of PβDF(178Aug) < 1.11(2) × 10−8 and PβDF(178Aum) < 9.7(2) × 10−9 were determined. Corresponding lower limits of βDF partial half-lives were deduced as well, and the results are discussed in the context of experimental systematics of βDF in the neutron-deficient region of the nuclear chart.
The anisotropic expansion rate of the local universe and its covariant cosmographic interpretation
(Institute of Physics, 2026) Kalbouneh, Basheer; Marinoni, Christian; Maartens, Roy; Bel, Julien; Santiago, Jessica; Clarkson, Chris; Sarma, Maharshi; Virey, Jean-Marc
Without making any assumption on the underlying geometry and metric of the local Universe, we provide a measurement of the expansion rate fluctuation field using the Cosmicflows-4 and Pantheon+ samples in the redshift range 0.01
Calibration-independent consistency test of DESI DR2 BAO and SNIa
(Institute of Physics, 2025) Dinda, Bikash Ranjan; Maartens, Roy; Clarkson, Chris
We investigate the consistency between DESI DR2 BAO and three SNIa datasets, Pantheon+, Union3, and DES-Y5. Our consistency test is calibration-independent since it is independent of cosmological nuisance parameters such as the absolute peak magnitudeMB and the comoving sound horizon at the baryon drag epochrd. Importantly, the test is also model-agnostic, independent of any model of dark energy or modified gravity. We define a tension parameter to quantify tension across different datasets compared to DESI DR2 BAO. The Pantheon+ and Union3 data have tension ≲ 1σ across their redshift ranges, whereas the DES-Y5 tension is ≳ 3σ nearz= 1. This hints that DES-Y5 data has significant offset values for redshifts close to 1, compared to the other SNIa datasets. Since this consistency test is independent of cosmological nuisance parameters, the tension is minimal: other consistency tests involving differences in nuisance parameters may show greater tension.
The evolutionary map of the universe: a new radio atlas for the southern hemisphere sky
(Cambridge University Press, 2025) Vaccari, Mattia; Hopkins, Andrew; Kapinska, Anna
We present the Evolutionary Map of the Universe (EMU) survey conducted with the Australian Square Kilometre Array Pathfinder (ASKAP). EMU aims to deliver the touchstone radio atlas of the southern hemisphere.We introduce EMU and review its science drivers and key science goals, updated and tailored to the current ASKAP five-year survey plan. The development of the survey strategy and planned sky coverage is presented, along with the operational aspects of the survey and associated data analysis, together with a selection of diagnostics demonstrating the imaging quality and data characteristics. We give a general description of the value-added data pipeline and data products before concluding with a discussion of links to other surveys and projects and an outline of EMU’s legacy value.
Testing OH megamaser identification methods in H i surveys: updated source-flagging algorithms and new detections in ALFALFA
(Institute of Physics, 2025) Baker, Andrew; Roberts, Hayley; Darling, Jeremy
OH megamasers (OHMs) are extragalactic masers found primarily in gas-rich galaxy major mergers. To date, only ∼120 OHMs have been cataloged since their discovery in 1982, and efforts to identify distinct characteristics of OHM host galaxies have remained inconclusive. As radio astronomy advances with next-generation telescopes and extensive 21 cm H i surveys, precursors to the Square Kilometre Array are expected to detect the 18 cm OH masing line with significantly increased frequency, potentially expanding the known OHM population tenfold. These detections, however, risk confusion with lower-redshift H i emitters unless accompanied by independent spectroscopic redshifts. Building on methods proposed by Roberts et al. for distinguishing these interloping OHMs via near- to mid-IR photometry and emission line frequencies, we apply these techniques to data from the Arecibo Legacy Fast ALFA [Arecibo L-band Feed Array] (ALFALFA) survey and a preliminary Aperture Tile In Focus (Apertif) H i emission line catalog from the Westerbork Synthesis Radio Telescope. Our study, utilizing the Apache Point Observatory 3.5 m telescope to obtain optical spectroscopic redshifts of 142 candidates (107 from ALFALFA and 35 from Apertif), confirms five new OHM host galaxies and reidentifies two previously catalogued OHMs misclassified as H i emitters in ALFALFA. These findings support the predictions from Roberts et al. and underscore the evolving landscape of radio astronomy in the context of next-generation telescopes.
The dependence of the type Ia supernova colour-luminosity relation on their host galaxy properties
(Oxford University Press, 2025) Ramaiya, Shruti; Vincenzi, Maria; Jarvis, Matthew J.; Wiseman, Philip; Sullivan, Mark
Using the Dark Energy Survey 5-yr sample, we determine the properties of type Ia supernova (SN Ia) host galaxies across a wide multiwavelength range - from the optical to far-infrared - including data from the Herschel and Spitzer space telescopes. We categorize the SNe Ia into three distinct groups according to the distribution of their host galaxies on the star formation rate (SFR) - stellar mass () plane. Each region comprises host galaxies at distinct stages in their evolutionary pathways: Region 1 - low-mass hosts; Region 2 - high-mass, star-forming hosts and Region 3 - high-mass, passive hosts. We find SNe Ia in host galaxies located in Region 1 have the steepest slope (quantified by) between their colours and luminosities, with. This differs at the significance level to SNe Ia in Region 3, which have the shallowest colour-luminosity slope with. After correcting SNe Ia in each subsample by their respective, events in Region 3 (high-mass, passive hosts) are mag (3\sigma$]]>) brighter, post-standardization. We conclude that future cosmological analyses should apply standardization relations to SNe Ia based upon the region in which the SN host galaxy lies in the SFR- plane. Alternatively, cosmological analyses should restrict the SN Ia sample to events whose host galaxies occupy a single region of this plane.
MIGHTEE/COSMOS-3D: the discovery of three spectroscopically confirmed radio-selected star-forming galaxies at z = 4.9–5.6
(Oxford University Press, 2026) Varadaraj, R G; Saxena, A; Fakiolas, S; Whittam, Imogen Helen; Jarvis, Matthew. J; Meyer, R A; Hale, C L; Kakiichi, K; Li, M; Champagne, J B; Jin, B; Li, Z J; Shuntov, M
Radio observations offer a dust-independent probe of star formation and active galactic nucleus (AGN) activity, but sufficiently deep data are required to access the cross-over luminosity between these processes at high redshift ((Formula presented)). We present three spectroscopically confirmed high-redshift radio sources (HzRSs) detected at 1.3 GHz at (Formula presented) –5.6, with radio luminosities spanning (Formula presented) –(Formula presented). These sources were first identified as high-redshift candidates through spectral energy distribution (SED) fitting of archival Hubble, James Webb Space Telescope (JWST) NIRCam + MIRI, and ground-based photometry, and then spectroscopically confirmed via the (Formula presented) emission line using wide-field slitless spectroscopy from JWST COSMOS-3D. The star formation rates (SFRs) measured from SED fitting, the (Formula presented) flux, and the 1.3 GHz luminosity, span (Formula presented) –(Formula presented), demonstrating broad agreement between these SFR tracers. We find that these three sources lie either on or 0.5–1.0 dex above the star-forming main sequence at (Formula presented) –6 and have undergone a recent burst of star formation. The sources have extended rest-ultraviolet (UV)/optical morphologies with no evidence for a dominant point source component, indicating that an AGN is unlikely to dominate their rest-UV and optical emission. Two of the sources have complex, multicomponent rest-frame UV/optical morphologies, suggesting that their starbursts may be triggered by merging activity. These HzRSs open up a new window towards probing radio emission powered by star formation alone at (Formula presented), representing a remarkable opportunity to begin tracing star formation, independent of dust, in the early Universe.
A multimechanism hybrid model of peaked-spectrum radio sources
(Institute of Physics, 2025) An, Fangxia; Sun, Guang-Chen; Li, Yichao
Peaked-spectrum (PS) sources exhibit turnover characteristics in their broad radio spectra. However, the mechanism underlying this phenomenon remains elusive. The two most common hypotheses are synchrotron self-absorption (SSA) and free–free absorption (FFA). By incorporating multiple absorption scenarios, we propose a multimechanism hybrid model, which aligns well with current observational data and provides a good physical explanation. Using data from the GLEAM survey, we identified a sample of 4315 sources with peak frequencies between approximately 72 and 3000 MHz, most of which are MHz-peaked-spectrum sources. Our analysis shows that FFA rather than SSA is the dominant mechanism in producing the spectral turnover for most of the sources in this sample. The index of the optically thick spectrum αthick has a lower boundary due to FFA, and the steeper αthick indicates a complex multiabsorption mechanism. In particular, the external FFA produces substantial αthick, which exhibits a weak correlation with the peak frequency. Future ultralong-wavelength observations would also provide data on the spectrum of these sources at even lower frequencies. Determining the absorption mechanism that shaped the spectrum of these sources would be a crucial part of understanding their nature.
iDaVIE v1.0: A virtual reality tool for interactive analysis of astronomical data cubes
(Elsevier B.V., 2026) Taylor, Russell A; Sivitilli, Alexander; Marchetti, Lucia
As modern astronomy confronts unprecedented data volumes, automated pipelines and machine-learning techniques have become essential for processing and analysis. As these workflows grow more complex, astronomers also require input and inspection tools that can keep pace. To address challenges in navigating multidimensional datasets for quality control and scientific interpretation, we present the immersive Data Visualisation Interactive Explorer (iDaVIE), a virtual reality (VR) software suite developed in collaboration with the astronomy community. iDaVIE enables users to import and render large 3D data cubes within a VR environment, offering real-time tools for selection, cropping, catalogue overlays, and exporting results back into existing pipelines. Built on the Unity engine and SteamVR, the system uses custom plug-ins for efficient data parsing, downsampling, and statistical calculations. The software has already been integrated into workflows such as verifying HI data cubes from MeerKAT, ASKAP, and APERTIF, refining detection masks, and identifying new sources. Its intuitive interface aims to reduce the cognitive load associated with higher-dimensional data, allowing researchers to focus more directly on scientific goals. As an open-source, scalable, and adaptable platform, iDaVIE supports continued development and integration with other tools. Version 1.0 marks a significant milestone, with planned enhancements including subcube loading, advanced rendering modes, video-generation scripts, and collaborative capabilities. By pairing immersive visualisation with robust interaction tools, iDaVIE seeks to transform how researchers engage with complex datasets and enhance productivity in the era of big data.
Weighing neutrinos with 21cm intensity mapping at the SKAO
(Institute of Physics, 2026) Autieri, G; Berti M; Spinelli, Marta; Haridasu, B S; Viel, M
We explore the constraining power of future 21cm intensity mapping (IM) observations at the SKAO, focusing primarily on the sum of neutrino masses, Σmν . We forecast observations of the 21cm IM auto-power spectrum as well as the 21cm IM and galaxy surveys cross-correlation power spectrum. We construct different synthetic data sets of observations for the 21cm IM observables in the redshift range 0 < z < 3. For galaxy clustering, we consider two stage-IV surveys to mimic a DESI-like and Euclid-like cross-correlation signal. We study the impact of assuming three different fiducial values for the sum of neutrino masses, i.e. Σmν = 0.06, 0.1, 0.4 eV, in the synthetic data sets. To investigate the constraining power of the forecasted 21cm observations, we build a likelihood code that will be made publicly available upon publication. The results of the analysis, obtained through Markov Chain Monte Carlo techniques, are promising. We find that the 21cm auto-power spectrum alone could provide an upper limit on the sum of neutrino masses of Σmν < 0.287 eV, at 95% confidence level, for the case of the lowest fiducial value of Σmν . This result is comparable to the upper limits provided by cosmic microwave background (CMB) observations alone. When combining the 21cm auto-power spectrum synthetic data set with Planck 2018 CMB measurements, we find a tighter upper limit of Σmν < 0.105 eV, which improves on the constraints from Planck alone. We obtain a similar result already at the level of 21cm and galaxy clustering cross-correlation power spectrum, whose detection is more easily achieved as they are less affected by systematic effects. Combining synthetic data sets with Planck 2018 data, we find the upper limits of Σmν < 0.116 eV and Σmν < 0.117 eV for the 21cm signal in cross-correlation with the DESI-like and Euclid-like surveys, respectively. These constraints are comparable to those obtained by combining Planck data with the 21cm auto-power spectrum synthetic data sets, thus supporting the case for 21cm cross-correlation detections.
Starburst galaxies in the hydra i cluster
(EDP Sciences, 2025) De la Casa, Clara; Hess, Kelley; Verdes-Montenegro, Lourdes; Kotulla, Ralf; Chen, Hao; Jarrett, Thomas; Cluver, Michelle; De Daniloff, Simon; Gendron-Marsolais, Marie-Lou; Carignan, Claude; Gallagher, John; Kraan-Korteweg, Renée; Lanjamasimanana, Roger
Studying the impact of environment on star formation and quenching pathways requires statistically relevant samples of galaxies in a wide mass range. We present a new catalog of 196 galaxies of the nearby Hydra I cluster out to ∼1.75r200, consisting of broad u,g,r,i,z along with narrowband Hα measurements. These deep optical images were obtained with the DECam camera (CTIO) and reach down to a surface brightness limit of μ(3σ 10″ × 10″) = 26.9 mag arcsec2 in the g band. We also report the HI properties for 89 cluster members detected with MeerKAT. A color magnitude diagram (CMD) shows a bimodal distribution typical of a cluster population, more evolved than those found in isolation. We combined optical Hα and WISE infrared data to compare the star formation history at two distinct timescales. Differences in the star-forming activity depicted by both populations manifest as a starburst in 24 found members. Of these, 18 starburst galaxies have neutral gas measurements, and they show disturbed HI disks that suggest an environmentally triggered boost in star formation within the last 107 yrs. Processes such as ram pressure stripping or tidal interactions may underlie their enhanced star-forming activity and asymmetric disks. Since Hydra s dynamical history is unclear, we examine the spatial and velocity distribution of the sample. We reveal a possible link between the large-scale structure feeding the Hydra I cluster and the heightened star-forming activity of the starburst galaxies. This feeding pattern matches the few substructures that have been identified in Hydra in previous works, and this may explain their origin. Our results portray a picture of a cluster with an evolved nature, plus a population of new infalling galaxies that manifest the impact of their first contact with the cluster environment through star formation, color, morphology, and gas content transformations.
Turnover detection using the power spectrum and bispectrum
(Institute of Physics, 2026) Dube, Yolanda; Dinda, Bikash; Jolicoeur, Sheean; Maartens, Roy
The turnover at the peak of the Fourier matter power spectrum encodes a fundamental signature of matter-radiation equality in the early Universe. This delivers a potential standard ruler, independent of baryon acoustic oscillations and therefore able to break parameter degeneracies and improve precision. Furthermore, the turnover scale is independent of redshift and clustering bias, allowing for stacking of the signals from redshift bins. In practice, the very large scale of the turnover means that sample variance and systematics are serious impediments to its detection. Detections of the turnover and measurements of its scale have been made in the WiggleZ, eBOSS, Quaia, and DESI surveys. Upcoming surveys should improve the detection significance and reduce errors on the turnover scale. We use MCMC forecasts for turnover detection in a spectroscopic Euclid-like survey and a futuristic MegaMapper-like survey. In addition to the power spectrum, we include the signal from the bispectrum in equilateral configurations. These surveys are forecast to detect the turnover at ∼6σ (Euclid-like) and ∼15σ (MegaMapper-like), with precision on the turnover scale of ∼ 4% and ∼ 2%. The inclusion of the bispectrum delivers a modest improvement of ∼ 10–17% in the constraints on the turnover scale.
Learning the universe: cosmological and astrophysical parameter inference with galaxy luminosity functions and colours
(Oxford University Press, 2025) Lovell, Christopher; Starkenburg, Tjitske; Ho, Matthew; Anglés-Alcázar, Daniel; Dav́e, Romeel; Gabrielpillai, Austen; Iyer, Kartheik; Matthews, Alice; Roper, William; Somerville, Rachel; Sommovigo, Laura; Villaescusa-Navarro, Francisco
We perform the first direct cosmological and astrophysical parameter inference from the combination of galaxy luminosity functions and colours using a simulation-based inference approach. Using the synthesizer code, we simulate the dust attenuated ultraviolet (UV)–near-infrared stellar emission from galaxies in thousands of cosmological hydrodynamic simulations from the CAMELS suite, including the swift-eagle, ILLUSTRISTNG, simba, and astrid galaxy formation models. For each galaxy, we calculate the rest-frame luminosity in a number of photometric bands, including the SDSS ugriz and GALEX far- and near-UV filters; this data set represents the largest catalogue of synthetic photometry based on hydrodynamic galaxy formation simulations produced to date, totalling > 200 million sources. From these, we compile luminosity functions and colour distributions, and find clear dependencies on both cosmology and feedback. We then perform simulation-based (likelihood-free) inference using these distributions to obtain constraints on Ωm, σ8, and four parameters controlling the strength of stellar and active galactic nucleus feedback. Both colour distributions and luminosity functions provide complementary information on certain parameters when performing inference. We achieve constraints on the stellar feedback parameters, as well as Ωm and σ8. The latter is attributable to the fact that the photometry encodes the star formation–metal enrichment history of each galaxy; galaxies in a universe with a higher σ8 tend to form earlier and have higher metallicities, which leads to redder colours. We find that a model trained on one galaxy formation simulation generalizes poorly when applied to another, and attribute this to differences in the subgrid prescriptions, and lack of flexibility in our emission modelling. The photometric catalogues are publicly available.
The odd-parity part of the observed galaxy trispectrum
(Institute of Physics, 2025) Paul, Pritha; Clarkson, Chris; Maartens, Roy
Recently the 4-point correlation function of the galaxy density contrast has been looked at to investigate parity violation in large scale structure surveys. The 4-point correlation function is the lowest order statistic which is sensitive to parity violation, since a tetrahedron is the simplest shape that cannot be superimposed on its mirror image by a rotation. If the parity violation is intrinsic in nature, this could give us a window into inflationary physics. However, we need to exhaust all other contaminations before we consider them to be intrinsic. Even though the standard Newtonian redshift-space distortions are parity symmetric, the full relativistic picture is not. Therefore, we expect a parity-odd trispectrum when observing in redshift space, due to the line-of-sight dependent effects. We calculate the trispectrum with the leading-order relativistic effects and investigate in detail the parameter space of the trispectrum and the effects of these relativistic corrections for different parameter values and configurations. We also look at different surveys and how the evolution and magnification biases can be affected by different parameter choices.
Competing ultrafast excitonic- and quasi-free-carrier-driven decay of optical excitations in cvd-grown 2d hybrid halide perovskites
(American Chemical Society, 2025) Babaian, Dallar; Abhi, Abhijeet; Arendse, Christopher Joseph; Hill, Daniel; Ullrich, Carsten A.; Yu, Ping; Guha, Suchismita
Two-dimensional (2D) organic–inorganic Ruddlesden–Popper (RP) halide perovskites emphasize a strong excitonic contribution, which enhances light-emission properties but decreases the photovoltaic efficiency. Decay dynamics using pump–probe spectroscopy provides insight into the initial makeup of the excited states. The decay of the ground state bleaching peak at 2.3 eV from chemical vapor deposited (CVD) films of phenylethylammonium lead iodide (PEA2 PbI4) with and without self-trapped excitons is investigated. Below a critical excited carrier density, which is in the low 1012 cm–2 and varies slightly in the presence of self-trapped excitons, the decay is dictated by both excitons and quasi-free carriers. At these carrier densities, the Saha equilibrium condition predicts only 5% of free carriers, suggesting that a small fraction of free carriers may catalyze entropy-driven exciton ionization, resulting in a strong contribution from Auger recombination. Beyond the critical excited carrier density, the system is primarily excitonic. A Sn-based CVD-grown 2D perovskite shows decay dynamics similar to those of the lead-based sample; however, it has a slower carrier cooling time of ∼1 ps compared with the fast cooling time in PEA2 PbI4.
Structure of 128Sn selectively populated in the β decay of the 128In ground state
(American Physical Society, 2025) Bernier, Nikita; Lesch, Brenden; Orce, José Nicolás
High-resolution γ -ray spectroscopy and fast-timing methods were employed to study the excited structure of 128Sn, populated via the β-decay chain of 128Cd → 128In → 128Sn. The experiment was performed by online mass separation at the ISOLDE facility at CERN, profiting from intense and pure Cd beams obtained by a temperature-controlled quartz transfer line combined with resonant laser ionization. An extended 128Sn level scheme populated in the β− decay of the low-spin 128In isomer was constructed, adding a total of 81 new γ -ray transitions and 30 new levels. Lifetimes of excited states were measured using time-delayed βγ (t) and γ γ (t) coincidences. The lifetime of the (4+) state was measured for the first time, making it possible to deduce the B(E2; 4+ → 2+) transition strength. The previously measured (5−) state was reassessed with improved statistics. Additionally, an upper limit for the lifetime of the state at 2378 keV was established. The derived reduced transition probabilities support a tentative spin-parity assignment of (4−) for this level. The experimental level scheme and transition probabilities are compared with available shell-model calculations.

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