Journal of Cosmology and Astroparticle Physics最新文献

{"title":"Measuring photo-ionization rate and mean free path of He ii ionizing photons at 2.5 ≤ z ≤ 3.6: evidence for late and rapid HeII reionization part II","authors":"Prakash Gaikwad, Fredrick B. Davies, Martin G. Haehnelt","doi":"10.1088/1475-7516/2025/09/057","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/057","url":null,"abstract":"We present measurements of the spatially averaged He <sc>ii</sc> photo-ionization\u0000rate (〈Γ_HeII〉), mean free path of He <sc>ii</sc>\u0000ionizing photons (λ_mfp,HeII), and He <sc>ii</sc> fraction (<italic toggle=\"yes\">f</italic>\u0000_HeII) across seven redshift bins within the redshift range 2 &lt; <italic toggle=\"yes\">z</italic> &lt; 4. The measurements\u0000are obtained by comparing the observed effective optical depth distribution of\u0000He <sc>ii</sc> (<italic toggle=\"yes\">τ</italic>\u0000_eff,HeII) with models generated by post-processing of the\u0000Sherwood simulation suite using our code <sc>ex-cite</sc>. With <sc>ex-cite</sc>, we\u0000efficiently explore a large parameter space (∼ 15000 models) by varying λ_mfp,HeII and 〈Γ_HeII〉. We employ a non-parametric Anderson-Darling test for the cumulative\u0000distribution of <italic toggle=\"yes\">τ</italic>\u0000_eff,HeII to simultaneously measure\u0000λ_mfp, HeII and 〈Γ_HeII〉. Our\u0000measurements account for possible observational and modeling uncertainties\u0000stemming mainly from the finite signal-to-noise ratio of the observed data and thermal\u0000parameter uncertainties. We find significant evolution, with the best-fit 〈Γ_HeII〉 and λ_mfp,HeII decreasing by\u0000factors of ∼ 4.32 and ∼ 3.27, respectively, from <italic toggle=\"yes\">z</italic> = 2.88 to <italic toggle=\"yes\">z</italic> =\u00003.16. This decreasing trend in 〈Γ_HeII〉 and\u0000λ_mfp,HeII suggests evolution of the size of ionized regions\u0000implying that HeII reionization is still ongoing at these redshifts.\u0000Based on these measurements, we constrain the emissivity at the He <sc>ii</sc> ionization\u0000frequency (<italic toggle=\"yes\">ϵ</italic>\u0000₂₂₈) and He <sc>ii</sc> ionizing photon emission rate\u0000(<italic toggle=\"yes\">ṅ</italic>), finding consistency with results from galaxy and QSO surveys.\u0000Comparison of our measured parameters with widely used uniform UVB models\u0000supports a scenario where He <sc>ii</sc> reionization is not completed before <italic toggle=\"yes\">z</italic> ∼ 2.74. Our measured evolution is complementary and in good agreement\u0000with recent measurements of thermal parameters of the IGM, suggesting a coherent picture of\u0000rather late and rapid He <sc>ii</sc> reionization.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"8 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145083989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"OLÉ — Online Learning Emulation in cosmology","authors":"Sven Günther, Lennart Balkenhol, Christian Fidler, Ali Rida Khalife, Julien Lesgourgues, Markus R. Mosbech, Ravi Kumar Sharma","doi":"10.1088/1475-7516/2025/09/059","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/059","url":null,"abstract":"In this work, we present <monospace>OLÉ</monospace>, a new online learning emulator for use in cosmological inference. The emulator relies on Gaussian Processes and Principal Component Analysis for efficient data compression and fast evaluation. Moreover, <monospace>OLÉ</monospace> features an automatic error estimation for optimal active sampling and online learning.\u0000All training data is computed on-the-fly, making the emulator applicable to any cosmological model or dataset.\u0000We illustrate the emulator's performance on an array of cosmological models and data sets, showing significant improvements in efficiency over similar emulators without degrading accuracy compared to standard theory codes.\u0000We find that <monospace>OLÉ</monospace> is able to considerably speed up the inference process, increasing the efficiency by a factor of 30-350, including data acquisition and training. Typically the runtime of the likelihood code becomes the computational bottleneck.\u0000Furthermore, <monospace>OLÉ</monospace> emulators are differentiable; we demonstrate that, together with the differentiable likelihoods available in the <monospace>candl</monospace> library, we can construct a gradient-based sampling method which yields an additional improvement factor of 4.\u0000<monospace>OLÉ</monospace> can be easily interfaced with the popular samplers <monospace>MontePython</monospace> and <monospace>Cobaya</monospace>, and the Einstein-Boltzmann solvers <monospace>CLASS</monospace> and <monospace>CAMB</monospace>.\u0000<monospace>OLÉ</monospace> is publicly available at <ext-link ext-link-type=\"uri\" xlink:href=\"https://github.com/svenguenther/OLE\" xlink:type=\"simple\">https://github.com/svenguenther/OLE</ext-link>.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"20 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145083993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ACT-inspired Kähler-based inflationary attractors","authors":"C. Pallis","doi":"10.1088/1475-7516/2025/09/061","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/061","url":null,"abstract":"We develop a new class of cosmological attractors which are compatible with the\u0000recent ACT results. They are based on two types of fractional Kähler potentials, <italic toggle=\"yes\">K</italic>, for a gauge-singlet inflaton <italic toggle=\"yes\">ϕ</italic> which reduce, along the inflationary path, to the form <italic toggle=\"yes\">N</italic>/(1-<italic toggle=\"yes\">ϕ</italic>\u0000^{\u0000<italic toggle=\"yes\">q</italic>\u0000_M\u0000})^{\u0000<italic toggle=\"yes\">p</italic>\u0000} with <italic toggle=\"yes\">q</italic>\u0000_M = 1,2 and 0.1 ≤ <italic toggle=\"yes\">p</italic> ≤ 10. The combination of these <italic toggle=\"yes\">K</italic>'s with the\u0000chaotic potentials <italic toggle=\"yes\">ϕⁿ\u0000</italic> (where <italic toggle=\"yes\">n</italic> = 2, 4) within a non-linear\u0000sigma model leads to inflationary observables which are consistent\u0000with the current data and largely independent from <italic toggle=\"yes\">q</italic>\u0000_M and <italic toggle=\"yes\">n</italic>.\u0000Endowing these <italic toggle=\"yes\">K</italic>'s with a shift symmetry we also offer a\u0000supergravity realization of our models introducing two chiral\u0000superfields and a monomial superpotential, linear with respect to\u0000the inflaton-accompanying field. The attainment of inflation with\u0000subplanckian inflaton values and the large values for the\u0000tensor-to-scalar ratio, which increases with <italic toggle=\"yes\">N</italic>, are two\u0000additional attractive features of our proposal.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"2 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145083970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The exact and approximate tales of boost-breaking cosmological correlators","authors":"Zhehan Qin, Sébastien Renaux-Petel, Xi Tong, Denis Werth, Yuhang Zhu","doi":"10.1088/1475-7516/2025/09/058","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/058","url":null,"abstract":"Cosmological correlators offer a remarkable window into the high-energy physics governing Universe's earliest moments, with the tantalising prospect of discovering new particles. However, extracting new physics from these observables requires both precise theoretical predictions of inflationary theories and accurate, analytical templates suitable for data analysis throughout parameter and kinematic spaces. In this paper, we extend the current analytical results by computing the most general boost-breaking seed correlator mediated by the tree-level exchange of a massive spinning particle. We derive the result using two complementary approaches, bootstrapping from boundary differential equations, and direct spectral integration. Both representations are packaged as a single partially resummed series that converges in all physical kinematics. Computing this correlator marks a milestone for carving out the space of all boost-breaking correlators, and therefore completes the tree-level catalogue. We then introduce a general procedure to obtain accurate approximations for cosmological collider signals based on the saddle-point method. This approach allows for a clear physical intuition of various signals hidden in correlators, as the bulk physics is made manifest through the location of these saddles in the complex time plane, which depend on the external kinematics. Evaluating the time integrals at these saddles yields results given as elementary functions that remain valid beyond soft limits and provide intuitive control over both the signal shape and amplitude. We demonstrate the power of this method in both de Sitter-invariant and boost-breaking scenarios, and uncover novel refined waveform and strength dependence for oscillatory signals from massive fields. We provide a complete cosmological collider shape template capturing all boost-breaking effects for upcoming cosmological surveys.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"79 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145083894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cosmology with persistent homology: parameter inference via machine learning","authors":"Juan Calles, Jacky H.T. Yip, Gabriella Contardo, Jorge Noreña, Adam Rouhiainen, Gary Shiu","doi":"10.1088/1475-7516/2025/09/064","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/064","url":null,"abstract":"Building upon previous work [1], we investigate the constraining power of persistent homology on cosmological parameters and primordial non-Gaussianity in a likelihood-free inference pipeline utilizing machine learning. We evaluate the ability of Persistence Images (PIs) to infer parameters, comparing them to the combined Power Spectrum and Bispectrum (PS/BS). We also compare two classes of models: neural-based and tree-based. PIs consistently lead to better predictions compared to the combined PS/BS for parameters that can be constrained, i.e., for {Ω_m, <italic toggle=\"yes\">σ</italic>\u0000₈, <italic toggle=\"yes\">n</italic>\u0000_s, <italic toggle=\"yes\">f</italic>\u0000_NL\u0000^loc}. PIs perform particularly well for <italic toggle=\"yes\">f</italic>\u0000_NL\u0000^loc, highlighting the potential of persistent homology for constraining primordial non-Gaussianity. Our results indicate that combining PIs with PS/BS provides only marginal gains, indicating that the PS/BS contains little additional or complementary information to the PIs. Finally, we provide a visualization of the most important topological features for <italic toggle=\"yes\">f</italic>\u0000_NL\u0000^loc and for Ω_m. This reveals that clusters and voids (0-cycles and 2-cycles) are most informative for Ω_m, while <italic toggle=\"yes\">f</italic>\u0000_NL\u0000^loc is additionally informed by filaments (1-cycles).","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"38 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145084003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Keeping the relation between the Starobinsky model and no-scale supergravity ACTive","authors":"Ioannis D. Gialamas, Theodoros Katsoulas, Kyriakos Tamvakis","doi":"10.1088/1475-7516/2025/09/060","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/060","url":null,"abstract":"We introduce a modification of the Starobinsky model in the form of an additional cubic Ricci scalar curvature term ∼ <italic toggle=\"yes\">αR</italic>\u0000³, scaled by a dimensionless parameter <italic toggle=\"yes\">α</italic>, with the resulting inflaton potential being the standard Starobinsky potential modified to first parametric order by an additive term. The resulting potential is identical to the potential obtained by a modification of the superpotential employed in the construction of the Starobinsky model in the framework of no-scale supergravity, thus, extending the correspondence between a class of no-scale supergravity models and modifications of the Starobinsky model. We analyze the inflationary predictions of the model and find that for -4.2 × 10^-5 ≲ <italic toggle=\"yes\">α</italic> ≲ -1.9 × 10^-5, the modified Starobinsky model is in full agreement with the recent observational data from the Atacama Cosmology Telescope, for a range of <italic toggle=\"yes\">e</italic>-folds, <italic toggle=\"yes\">N</italic>\u0000_★ = 50–60.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"18 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145083996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The long freeze: an asymptotically static universe from holographic dark energy","authors":"Samuel Blitz, Robert J. Scherrer, Oem Trivedi","doi":"10.1088/1475-7516/2025/09/063","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/063","url":null,"abstract":"We show that some holographic dark energy models\u0000can lead to a future evolution of the universe in which <italic toggle=\"yes\">ȧ</italic> → 0, so\u0000the scale factor a is asymptotically constant, while\u0000the corresponding energy and\u0000pressure densities vanish. We provide specific examples of such models and general conditions that can lead to an asymptotically static universe,\u0000which we have called the “long freeze”. In some cases, such evolution can follow\u0000an arbitrarily long exponential expansion essentially\u0000identical to the asymptotic evolution of ΛCDM. When nonrelativistic matter is\u0000added to the holographic dark energy, it tends to\u0000destroy the long freeze behavior, driving the universe to recollapse. We show that a long freeze evolution is still possible, but only for\u0000a more limited set of holographic dark energy models.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"37 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145083997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Higgs-like inflation ACTivated mass","authors":"Wen Yin","doi":"10.1088/1475-7516/2025/09/062","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/062","url":null,"abstract":"Recent analyses that combine the latest data from the Atacama Cosmology Telescope (ACT) with cosmic microwave background observations by BICEP/Keck and Planck, together with the DESI baryon acoustic-baryonic-oscillation (BAO) measurements, have tightened the limits on inflationary scenarios. The joint data set yields a spectral index of primordial scalar perturbations\u0000<italic toggle=\"yes\">n_s\u0000</italic> = 0.9743 ± 0.0034 and an upper bound on the tensor-to-scalar ratio of <italic toggle=\"yes\">r</italic> &lt; 0.038.\u0000This slight upward shift in <italic toggle=\"yes\">n_s\u0000</italic> puts the previously favored Starobinsky model, and the conventional metric Higgs(-like) inflation-based on a quartic potential with a large non-minimal coupling in the Jordan frame-under tension with observations. In metric Higgs-like inflation the attractor behavior makes the predictions remarkably stable against higher-order operators, so modifying <italic toggle=\"yes\">n_s\u0000</italic> through such terms is difficult.\u0000In this paper, I show that adding a quadratic mass term to the Jordan-frame potential can raise <italic toggle=\"yes\">n_s\u0000</italic> and restore compatibility with the new data.\u0000I also discuss how this mass term can naturally arise from threshold effects in Higgs inflation.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"73 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145083995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The lifespan of our universe","authors":"Hoang Nhan Luu, Yu-Cheng Qiu and S.-H. Henry Tye","doi":"10.1088/1475-7516/2025/09/055","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/055","url":null,"abstract":"The Dark Energy Survey (DES) and the Dark Energy Spectroscopic Instrument (DESI) measurements claim that the dark energy equation of state w ≠ -1. This observation can be explained by the axion Dark Energy (aDE) model of an ultralight axion plus a cosmological constant Λ. Despite a relatively large degeneracy, there is a high probability that Λ<0. This negative Λ leads the universe to end in a big crunch. Using the best-fit values of the model as a benchmark, we find the lifespan of our universe to be 33 billion years.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"96 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145078114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the connection between field-level inference and n-point correlation functions","authors":"Fabian Schmidt","doi":"10.1088/1475-7516/2025/09/056","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/09/056","url":null,"abstract":"Bayesian field-level inference of galaxy clustering guarantees optimal extraction of all cosmological information, provided that the data are correctly described by the forward model employed. The latter is unfortunately never strictly the case. A key question for field-level inference approaches then is where the cosmological information is coming from, and how to ensure that it is robust. In the context of perturbative approaches such as effective field theory, some progress on this question can be made analytically. We derive the parameter posterior given the data for the field-level likelihood given in the effective field theory, marginalized over initial conditions in the zero-noise limit. Particular attention is paid to cutoffs in the theory, the generalization to higher orders, and the error made by an incomplete forward model at a given order. The main finding is that, broadly speaking, an m-th order forward model captures the information in n-point correlation functions with n ≤ m + 1. Thus, by adding more terms to the forward model, field-level inference is made to automatically incorporate higher-order n-point functions. Also shown is how the effect of an incomplete forward model (at a given order) on the parameter inference can be estimated.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"22 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145077707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}