Journal of Cosmology and Astroparticle Physics最新文献

{"title":"Structure and mass-radius stability of charged compact objects in symmetric teleparallel Euler–Heisenberg gravity","authors":"Allah Ditta, M. Yousaf, G. Mustafa, S.K. Maurya, Farruh Atamurotov, Orhan Donmez and Sardor Murodov","doi":"10.1088/1475-7516/2026/07/053","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/053","url":null,"abstract":"In this work, we studied a relativistic model of a charged anisotropic compact star within the paradigm of modified symmetric teleparallel gravity coupled to nonlinear electrodynamics, namely f(Q)-Euler-Heisenberg gravity. The combined influence of non-metricity and quantum electrodynamic corrections introduces an effective stiffening of stellar matter, allowing the formation of compact objects with denser mass and compactness than those models suggested by general relativity. By adopting the MIT bag model equation of state, we obtain exact interior solutions elaborating an anisotropic fluid configuration interacting with a nonlinear electromagnetic field. The interior spacetime is smoothly matched to the corresponding exterior geometry derived within the same f(Q)-Euler-Heisenberg framework by means of the Darmois-Israel junction conditions. A detailed physical analysis of the results show that the energy density, radial and tangential pressures, anisotropy, and sound speeds remain regular throughout the stellar interior and satisfy all essential physical requirements. The equilibrium of the configuration is governed by a balance between gravitational, hydrostatic, electromagnetic, and anisotropic forces, as demonstrated by the generalized Tolman-Oppenheimer-Volkoff equation. The dynamical stability of the model is further ensured by the adiabatic index condition Γ > 4/3, indicating robustness against small radial perturbations. The resulting mass-radius relations, compactness, and surface redshift profiles exhibit smooth and physically acceptable behavior. When applied to observed compact object candidate PSR J1614-2230, the predicted mass and radius are consistent with current observational constraints. Instead of graphical analysis, we numerically calculated the predicted radius for five star candidates (PSRJ 1614-2230, PSR J074+6620, PSR J1959+2048, PSR J2215+5135, GW190814) which are again consistent with current observational constraints. These results demonstrate that the f(Q)-Euler-Heisenberg framework provides a physically viable extension of standard gravity capable of supporting heavier and more compact stellar configurations than those allowed within classical general relativity.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"37 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148441385","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":"Search for sterile neutrinos with CUPID-0","authors":"O. Azzolini, J.W. Beeman, F. Bellini, M. Beretta, M. Biassoni, C. Brofferio, C. Bucci, S. Capelli, V. Caracciolo, L. Cardani, P. Carniti, N. Casali, E. Celi, D. Chiesa, M. Clemenza, I. Colantoni, O. Cremonesi, A. Cruciani, A. D'Addabbo, I. Dafinei, S. Di Domizio, F. Ferroni, L. Gironi, A. Giuliani, P. Gorla, C. Gotti, L. Gráf, G. Keppel, J. Kotila, M. Martinez, S. Nagorny, M. Nastasi, S. Nisi, C. Nones, D. Orlandi, L. Pagnanini, M. Pallavicini, L. Pattavina, M. Pavan, G. Pessina, L. Petrillo, V. Pettinacci, S. Pietrarota, S. Pirro, S. Pozzi, E. Previtali, A. Puiu, A. Ressa, C. Rusconi, K. Schäffner, C. Tomei, M. Vignati, A.S. Zolotarova and The CUPID-0 collaboration","doi":"10.1088/1475-7516/2026/07/052","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/052","url":null,"abstract":"Sterile neutrinos are well-motivated extensions of the Standard Model, introduced to address fundamental questions such as the origin of neutrino masses and the nature of dark matter. Exploiting the precise data reconstruction achieved by the CUPID-0 experiment, we searched for spectral distortions in the double β-decay of 82Se compatible with the emission of a sterile neutrino. The analysis relies on the construction of a detailed background model down to 200 keV, enabling an accurate characterization of the main sources of contamination. Using a Zn82Se exposure of 9.95 kg·yr, we explored sterile neutrino mass hypotheses between 0.5 MeV and 1.5 MeV. No evidence for a signal was observed in any scenario; therefore, we derived 90% C.I. upper limits on the active-sterile mixing probability sin2θ, obtaining the most stringent bound, sin2θ < 8 × 10-3, for a sterile neutrino mass of 0.7 MeV.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"11 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148441393","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":"Non-linear dynamics and primordial black hole formation during kination","authors":"Cheng Cheng, Panagiotis Giannadakis, Lucien Heurtier and Eugene A. Lim","doi":"10.1088/1475-7516/2026/07/048","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/048","url":null,"abstract":"We investigate the effects of large scalar inhomogeneities during the kination epoch, a period in which the universe's dynamics are dominated by the kinetic energy of a scalar field, by fully evolving the Einstein equations using numerical relativity. By tracking the non-linear growth of scalar perturbations with both sub-horizon and super-horizon initial wavelengths, we are able to compare their evolution to perturbative results. Our key findings show that in the deep sub-horizon limit, the perturbative behaviour remains valid, whereas in the super-horizon regime, non-linear dynamics exhibit a much richer phenomenology. Finally, we discuss the possibility of primordial black hole formation from the collapse of such perturbations and assess whether this process could serve as a viable mechanism to reheat the universe in the post-inflationary era.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"37 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148432438","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 BAO scale — how standard is the standard ruler?","authors":"Francisco Asensio-Rivera, Nils Schöneberg, Héctor Gil-Marín and Licia Verde","doi":"10.1088/1475-7516/2026/07/046","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/046","url":null,"abstract":"Analyses of baryon acoustic oscillations (BAO) commonly employ template-based methods to extract compressed parameters from the clustering of dark-matter tracers, which are then interpreted in terms of ratios of the sound-horizon scale and cosmological distances relative to a fiducial cosmology. A small mismatch between the sound-horizon scale derived from the standard analytic formulation (integral over the sound speed) and the effective scale imprinted in clustered matter can, however, introduce a systematic bias in cosmological inference. We extend previous work to a broader class of cosmological models, quantify this bias for surveys with DESI-like precision, and propose strategies to correct for the effect. We find that the induced bias becomes a significant fraction of the statistical uncertainty for deviations from the fiducial cosmology, at the level of |ΔΩm| = 0.03 and |ΔNeff| = 0.3, and for very precise data corresponding to a forecasted Year-5 DESI survey (or other stage IV dark energy galaxy surveys). We present several ways to correct for this effect, suitable for a variety of applications. We therefore recommend that analyses exploring such parameter regimes either apply the proposed corrections or include an appropriate systematic error budget.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"34 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148432309","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":"Identifying microlensing by compact dark matter through diffraction patterns in gravitational waves with machine learning","authors":"Ao Liu, Jiaxing Cui, Tonghua Liu, Dejiang Li, Cuihong Wen, Kai Liao, Huan Zhou and Jieci Wang","doi":"10.1088/1475-7516/2026/07/044","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/044","url":null,"abstract":"Gravitational wave (GW) microlensing induced by compact dark matter (DM) offers an unparalleled opportunity to explore the fundamental nature of dark matter, as it enables the detection of optically invisible compact objects that are otherwise inaccessible to electromagnetic observations. Conventional approaches for identifying such lensed GW signals suffer from inherent drawbacks: matched-filtering algorithms struggle with the complex, parameter-sensitive diffraction patterns of wave-optics microlensing due to template bank limitations. Additionally, weak lensed signals can be easily obscured by background noise, leading to challenges in maintaining high detection reliability in low signal-to-noise ratio (SNR) regimes. In this work, we introduce the Wavelet Convolution Detector (WCD), a deep learning framework tailored to identify wave-optics diffraction imprints in lensed GW signals. The WCD integrates multi-scale wavelet analysis into residual convolutional blocks, enabling efficient extraction of subtle time-frequency interference structures characteristic of microlensing. To ensure generalization to realistic astrophysical scenarios, the model is trained on a physically motivated synthetic dataset that incorporates realistic distributions of compact DM masses, lens redshifts, and lensing probabilities. Evaluated on simulated binary black hole (BBH) events injected into Gaussian noise mimicking third-generation GW detector environments, the WCD achieves a test accuracy of 92.2% and an Area Under the Receiver Operating Characteristic Curve (AUC) of 0.966. At a stringent false positive rate of 3%, the model maintains a true positive rate of 86.5%, demonstrating robust performance in distinguishing subtle wave-optics imprints from stochastic noise. This makes the WCD a scalable, efficient tool for large-scale blind searches of compact DM candidates via GW microlensing in the upcoming era of third-generation GW detectors.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"10 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148432307","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":"Shapes and orientations of massive halos in the statistically anisotropic universe","authors":"Shogo Masaki, Yurino Mizuguchi, Shohei Saga and Shuichiro Yokoyama","doi":"10.1088/1475-7516/2026/07/049","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/049","url":null,"abstract":"We investigate how statistical anisotropy (SA) in matter distributions affects the distributions of shapes and orientations of cluster-sized halos, using cosmological N-body simulations that incorporate SA. While the three-dimensional halo shape parameters show little dependence on SA, we find that halo orientations are significantly influenced, with halos tending to align either perpendicular or parallel to the SA direction. This SA-induced alignment becomes more prominent for more massive halos. We also study other vector quantities associated with the dynamics of halos, such as bulk velocity and angular momentum vectors. We find that their dependences on the SA are smaller than those of the orientation vectors. Our findings suggest that observational measurements of projected halo shapes derived from galaxy cluster-galaxy lensing could provide a novel probe of SA in the universe.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"17 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148432439","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":"Are primordial black holes truly fine-tuned?","authors":"A.J. Iovino and A. Riotto","doi":"10.1088/1475-7516/2026/07/047","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/047","url":null,"abstract":"Single-field inflationary models which generate primordial black holes through the enhancement of the curvature primordial power at small scales are commonly criticized and frequently dismissed because they require a large amount of fine-tuning in the parameters setting the ultra slow-roll phase. However, the standardly adopted definition of fine-tuning has a clear drawback: the more the primordial black hole abundance is small and cosmologically harmless, the larger the parameter space is fine-tuned. A well-defined indicator of fine-tuning should assign large values to scenarios requiring significant parameter adjustment to reproduce the desired primordial black hole abundance, while yielding values of order unity in cases governed by standard sensitivity. Motivated by such arguments, we use the (modified version of) Wilson's naturalness criterion for quantifying the fine-tuning and naturalness and we show that the primordial black hole models are not technically unnatural.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"16 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148432311","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":"Modified Friedmann equations and non-singular cosmologies in d = 4 non-polynomial quasi-topological gravities","authors":"Johanna Borissova and João Magueijo","doi":"10.1088/1475-7516/2026/07/045","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/045","url":null,"abstract":"Quasi-topological theories of gravity are known to resolve black-hole singularities. We investigate whether the same mechanism can remove cosmological singularities. Focusing on non-polynomial curvature quasi-topological gravities in d = 4 dimensions, we find three generic scenarios with the correct infrared limit but without a Big-Bang singularity, for universes filled with pure radiation or other standard matter. The first scenario yields a universe emerging from a de Sitter phase, a case for which the curvature invariants remain finite but the matter density diverges, albeit only at infinite affine distance. The second one corresponds to a bouncing universe, and requires a multi-valued Lagrangian. The third possibility is an asymptotically Minkowski origin, reminiscent of an eternally loitering universe. The matter energy density for this solution is non-singular even at infinite affine distance and does not enter a super-Planckian regime, but is instead approximately constant for the past eternity.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"16 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148432002","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":"A no-go theorem in bumblebee vector-tensor cosmology","authors":"Carsten van de Bruck, Mohammad Ali Gorji, Nils A. Nilsson, Masroor C. Pookkillath and Masahide Yamaguchi","doi":"10.1088/1475-7516/2026/07/043","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/043","url":null,"abstract":"Bumblebee models, a class of vector-tensor theories in which a vector field acquires a nonzero vacuum expectation value that spontaneously breaks spacetime symmetries, are ubiquitous in the literature. By constructing the most general bumblebee action from all diffeomorphism-invariant marginal operators together with a general potential, aiming to cover all the bumblebee models studied in the literature, we perform a complete linear perturbation analysis on a spatially flat FLRW background. We show that for generic marginal couplings, the scalar sector propagates extra degrees of freedom beyond the single scalar expected for a massive vector. Enforcing the correct number of propagating modes in a cosmological setup forces degeneracy relations between the marginal couplings, which in turn completely fix the potential at the background level and render the remaining scalar infinitely strongly coupled already at linear order of perturbations. We establish a no-go theorem stating that the following conditions cannot be simultaneously satisfied: (i) the most general marginal action, (ii) a homogeneous and isotropic background, (iii) no extra propagating degrees of freedom around a spatially flat FLRW background, and (iv) healthy cosmological perturbations.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"22 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148432010","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":"Co-evolution of cosmic ray energy spectra, composition, and anisotropies","authors":"Bing-Qiang Qiao, Qiang Yuan and Yi-Qing Guo","doi":"10.1088/1475-7516/2026/07/050","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/07/050","url":null,"abstract":"The origin of cosmic rays remains an unresolved fundamental problem in astrophysics. The synergy of multiple observational probes, including the energy spectra, the mass composition, and anisotropy is a viable way to jointly uncover this mystery. In this work, we propose that the energy-dependence of those observables in a wide energy range, from O(10) GeV to ultrahigh energies of 1011 GeV, share quite a few correlated features, indicating a strong co-evolution which could be a consequence of the underlying origin of different source populations. We decipher these structures with a four-component model, i.e., the ensemble of Galactic sources, a local source close to the solar system, and the ensemble of two extragalactic source populations. In this scenario, the O(102) GV hardening and O(10) TV bump is due to the contribution of the local source, the knee is due to the maximum acceleration energy of protons by the Galactic source population, the second knee is due to the maximum acceleration energy of iron nuclei by Galactic sources, the dip feature between the two knees is due to the appearance of the extragalactic component, the ankle comes from the transition from one extragalactic component to the other, and the spectral suppression at the highest energies arises from the acceleration limit of the second extragalactic component. The transition from Galactic to extragalactic origin of cosmic rays occurs around O(108) GeV, which is smaller than the ankle energy.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"37 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148432313","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}