Pub Date : 2026-03-06DOI: 10.1088/1475-7516/2026/03/022
L. Pizzuti, A. Biviano, K. Umetsu, E. Agostoni, A. Autorino, A.M. Pombo, A. Mercurio and M. D'Addona
We investigate the anisotropic stress parameter, η = Ψ/Φ, defined as the ratio of the gravitational potentials in the linearly perturbed Friedmann-Lemaître Robertson-Walker metric, as a probe of deviations from general relativity across astrophysical to cosmological scales. Using mass profiles reconstructed from high-precision lensing and kinematics of nine galaxy clusters from the CLASH-VLT sample, we derive η(r) as a function of the radial distance from the cluster centres, over the range [0.1 Mpc,1.2 r200L], where r200L is virial radius best-fit from lensing data. When using a Navarro-Frenk-White or an Hernquist profile to model the total matter distribution, we find consistency with general relativity (η = 1) within 2σ for the full radial range for all the sampled clusters. However, adopting a Burkert profile introduces mild tension with general relativity, reaching the 3σ level in two systems. Assuming a negligible time-dependence in the redshift range spawned by the clusters, we obtain the joint constraint η (η = 1.0 Mpc) = 0.93+0.48-0.40 (stat) ± 0.47 (syst) at 95% confidence level — an improvement of approximately 40% over previous estimates. We discuss the impact of systematics on the constraints, and we highlight the implications of this result for current and upcoming cluster surveys.
{"title":"CLASH-VLT: Constraining deviation from GR with the mass profiles of nine massive galaxy clusters","authors":"L. Pizzuti, A. Biviano, K. Umetsu, E. Agostoni, A. Autorino, A.M. Pombo, A. Mercurio and M. D'Addona","doi":"10.1088/1475-7516/2026/03/022","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/03/022","url":null,"abstract":"We investigate the anisotropic stress parameter, η = Ψ/Φ, defined as the ratio of the gravitational potentials in the linearly perturbed Friedmann-Lemaître Robertson-Walker metric, as a probe of deviations from general relativity across astrophysical to cosmological scales. Using mass profiles reconstructed from high-precision lensing and kinematics of nine galaxy clusters from the CLASH-VLT sample, we derive η(r) as a function of the radial distance from the cluster centres, over the range [0.1 Mpc,1.2 r200L], where r200L is virial radius best-fit from lensing data. When using a Navarro-Frenk-White or an Hernquist profile to model the total matter distribution, we find consistency with general relativity (η = 1) within 2σ for the full radial range for all the sampled clusters. However, adopting a Burkert profile introduces mild tension with general relativity, reaching the 3σ level in two systems. Assuming a negligible time-dependence in the redshift range spawned by the clusters, we obtain the joint constraint η (η = 1.0 Mpc) = 0.93+0.48-0.40 (stat) ± 0.47 (syst) at 95% confidence level — an improvement of approximately 40% over previous estimates. We discuss the impact of systematics on the constraints, and we highlight the implications of this result for current and upcoming cluster surveys.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"46 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147360986","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}
Pub Date : 2026-03-05DOI: 10.1088/1475-7516/2026/03/015
Tal Adi
We present a model-independent null test of the late-time cosmological response to a reduced sound horizon, as typically required by early-universe solutions to the Hubble tension. In this approach, we phenomenologically impose a shorter sound horizon without modeling early-universe physics to isolate its impact on late-time dark energy inference. Using baryon acoustic oscillations (BAO), supernovae (SN), big bang nucleosynthesis (BBN), and local H0 data, while explicitly avoiding CMB anisotropies, we examine how this calibration shift propagates into constraints on the dark energy equation of state. We find that lowering rd systematically drives the w0-wa posterior toward less dynamical, quintessence-like behavior, bringing it closer to ΛCDM. This result underscores that some of the apparent evidence for evolving or phantom-like dark energy may reflect early-universe assumptions rather than genuine late-time dynamics. More broadly, our analysis highlights the importance of carefully disentangling calibration effects from physical evolution in interpreting forthcoming results from DESI and future surveys.
{"title":"Lowering the horizon on Dark Energy: A late-time response to early solutions for the Hubble tension","authors":"Tal Adi","doi":"10.1088/1475-7516/2026/03/015","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/03/015","url":null,"abstract":"We present a model-independent null test of the late-time cosmological response to a reduced sound horizon, as typically required by early-universe solutions to the Hubble tension. In this approach, we phenomenologically impose a shorter sound horizon without modeling early-universe physics to isolate its impact on late-time dark energy inference. Using baryon acoustic oscillations (BAO), supernovae (SN), big bang nucleosynthesis (BBN), and local H0 data, while explicitly avoiding CMB anisotropies, we examine how this calibration shift propagates into constraints on the dark energy equation of state. We find that lowering rd systematically drives the w0-wa posterior toward less dynamical, quintessence-like behavior, bringing it closer to ΛCDM. This result underscores that some of the apparent evidence for evolving or phantom-like dark energy may reflect early-universe assumptions rather than genuine late-time dynamics. More broadly, our analysis highlights the importance of carefully disentangling calibration effects from physical evolution in interpreting forthcoming results from DESI and future surveys.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358772","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}
Pub Date : 2026-03-05DOI: 10.1088/1475-7516/2026/03/006
Alexander B. Kaganovich
The Higgs sector of the Two-Measure Theory (TMT) extension of the electroweak SM (TMSM) is studied in the context of cosmology, where the only non-zero component φ of the cosmologically averaged Higgs field plays the role of the inflaton. The self-consistency of the system of equations obtained from the original action has the form of an algebraic constraint defining the scalar ζ, which is the ratio of two volume measures, as a function of the field φ and its first derivatives. The scalar ζ is present in all equations of motion and has a significant effect on the dynamics of the fields. After the transition in the equations of motion to the Einstein frame with the spatially flat Friedmann metric, it is convenient to describe the resulting system of equations using the action Seff and the Lagrangian Leff, which we call the TMT-effective action and the TMT-effective Lagrangian and from which these equations can be obtained. Due to the constraint, the original model parameters are converted in Leff into φ-dependent classical effective parameters. In particular, the effective potential Ueff(φ) in Leff has the form Ueff = λ/4ξ2MP4· F(φ)·tanh4(√(ξ)φ/MP), where F(φ) is a smooth function equal to F(φ) ≈ 1/2 for φ > 6MP. It is fundamentally important that the constant ξ of non-minimal coupling to the scalar curvature can be chosen small. If ξ = 1/6, then to ensure agreement with CMB observational data, the Higgs field self-coupling parameter λ in the original action must be of the order of ∼ 10-11. During cosmological evolution after the end of inflation, the decrease of φ leads to a change in the sign of the effective Higgs mass term in Leff. This TMSM effect provides an answer to the mystery of the Higgs potential structure and leads to spontaneous symmetry breaking. As φ approaches VEV, the scalar function ζ(φ) changes in such a way that the classical TMT-effective self-coupling parameter λ(ζ(φ)) increases by 10 orders of magnitude compared to λ, which is necessary for the implementation of the GWS theory. Applying the model to the very beginning of the classical evolution of the Universe shows that under certain initial conditions, cosmological dynamics can begin with a “pathological” and even phantom regime preceding inflation. However, if evolution begins with normal dynamics, then it proceeds only as inflation, and the problem of initial conditions for the onset of inflation does not arise. The fermion preheating model is described as a preliminary study of preheatig after inflation. Mathematical and physical arguments in favor of using the TMT are presented.
{"title":"Higgs inflation model with small non-minimal coupling constant","authors":"Alexander B. Kaganovich","doi":"10.1088/1475-7516/2026/03/006","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/03/006","url":null,"abstract":"The Higgs sector of the Two-Measure Theory (TMT) extension of the electroweak SM (TMSM) is studied in the context of cosmology, where the only non-zero component φ of the cosmologically averaged Higgs field plays the role of the inflaton. The self-consistency of the system of equations obtained from the original action has the form of an algebraic constraint defining the scalar ζ, which is the ratio of two volume measures, as a function of the field φ and its first derivatives. The scalar ζ is present in all equations of motion and has a significant effect on the dynamics of the fields. After the transition in the equations of motion to the Einstein frame with the spatially flat Friedmann metric, it is convenient to describe the resulting system of equations using the action Seff and the Lagrangian Leff, which we call the TMT-effective action and the TMT-effective Lagrangian and from which these equations can be obtained. Due to the constraint, the original model parameters are converted in Leff into φ-dependent classical effective parameters. In particular, the effective potential Ueff(φ) in Leff has the form Ueff = λ/4ξ2MP4· F(φ)·tanh4(√(ξ)φ/MP), where F(φ) is a smooth function equal to F(φ) ≈ 1/2 for φ > 6MP. It is fundamentally important that the constant ξ of non-minimal coupling to the scalar curvature can be chosen small. If ξ = 1/6, then to ensure agreement with CMB observational data, the Higgs field self-coupling parameter λ in the original action must be of the order of ∼ 10-11. During cosmological evolution after the end of inflation, the decrease of φ leads to a change in the sign of the effective Higgs mass term in Leff. This TMSM effect provides an answer to the mystery of the Higgs potential structure and leads to spontaneous symmetry breaking. As φ approaches VEV, the scalar function ζ(φ) changes in such a way that the classical TMT-effective self-coupling parameter λ(ζ(φ)) increases by 10 orders of magnitude compared to λ, which is necessary for the implementation of the GWS theory. Applying the model to the very beginning of the classical evolution of the Universe shows that under certain initial conditions, cosmological dynamics can begin with a “pathological” and even phantom regime preceding inflation. However, if evolution begins with normal dynamics, then it proceeds only as inflation, and the problem of initial conditions for the onset of inflation does not arise. The fermion preheating model is described as a preliminary study of preheatig after inflation. Mathematical and physical arguments in favor of using the TMT are presented.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"14 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358764","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}
Pub Date : 2026-03-05DOI: 10.1088/1475-7516/2026/03/013
Julian Adamek and Renan Boschetti
Spatial curvature is one of the fundamental cosmological parameters that is routinely constrained from observations. The forward modelling of observations, in particular of large-scale structure, often relies on large cosmological simulations. While the so-called separate universe approach allows one to account for the effect of curvature on the expansion rate in small sub-volumes, the non-Euclidean geometry is harder to accommodate. It becomes important when observables are computed over large distances, e.g. when photons travel to us from high redshift. Here we present a fully relativistic framework to run cosmological simulations for curved spatial geometry. The issue of consistent boundary conditions is solved by embedding a spherical cap of the curved spacetime into a hole within a flat exterior, where it can undergo free expansion. The geometric nature of gravity is made explicit in our framework, allowing for a consistent forward modelling of observables inside the curved patch. Our methodology would also work with any Newtonian code to a good approximation, requiring changes only to the initial conditions and post-processing.
{"title":"Incorporating curved geometry in cosmological simulations","authors":"Julian Adamek and Renan Boschetti","doi":"10.1088/1475-7516/2026/03/013","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/03/013","url":null,"abstract":"Spatial curvature is one of the fundamental cosmological parameters that is routinely constrained from observations. The forward modelling of observations, in particular of large-scale structure, often relies on large cosmological simulations. While the so-called separate universe approach allows one to account for the effect of curvature on the expansion rate in small sub-volumes, the non-Euclidean geometry is harder to accommodate. It becomes important when observables are computed over large distances, e.g. when photons travel to us from high redshift. Here we present a fully relativistic framework to run cosmological simulations for curved spatial geometry. The issue of consistent boundary conditions is solved by embedding a spherical cap of the curved spacetime into a hole within a flat exterior, where it can undergo free expansion. The geometric nature of gravity is made explicit in our framework, allowing for a consistent forward modelling of observables inside the curved patch. Our methodology would also work with any Newtonian code to a good approximation, requiring changes only to the initial conditions and post-processing.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358770","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}
Pub Date : 2026-03-05DOI: 10.1088/1475-7516/2026/03/014
Abhishek Roy and Rameswar Sahu
The scotogenic model provides a minimal and elegant framework that simultaneously explains neutrino masses and accommodates a viable dark matter (DM) candidate. In this work, we investigate the phenomenology of fermionic DM in the scotogenic model, with a particular emphasis on the effects of a non-standard cosmological history characterized by a low reheating temperature. We demonstrate that entropy injection from inflaton decay can significantly dilute the DM abundance, thereby relaxing the annihilation cross section required to reproduce the observed relic density and opening new regions of viable parameter space. We further analyze the complementarity between current and future direct detection experiments and charged lepton flavour violation (cLFV) searches in probing this scenario. Our results show that next-generation direct detection experiments such as DARWIN and XLZD, together with upcoming cLFV searches (in particular the future sensitivity of μ → 3e and μ → e conversion experiments), will be capable of testing substantial regions of the parameter space, including those associated with low reheating temperatures.
{"title":"Scrutinizing fermionic Dark Matter in scotogenic model with low reheating temperature","authors":"Abhishek Roy and Rameswar Sahu","doi":"10.1088/1475-7516/2026/03/014","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/03/014","url":null,"abstract":"The scotogenic model provides a minimal and elegant framework that simultaneously explains neutrino masses and accommodates a viable dark matter (DM) candidate. In this work, we investigate the phenomenology of fermionic DM in the scotogenic model, with a particular emphasis on the effects of a non-standard cosmological history characterized by a low reheating temperature. We demonstrate that entropy injection from inflaton decay can significantly dilute the DM abundance, thereby relaxing the annihilation cross section required to reproduce the observed relic density and opening new regions of viable parameter space. We further analyze the complementarity between current and future direct detection experiments and charged lepton flavour violation (cLFV) searches in probing this scenario. Our results show that next-generation direct detection experiments such as DARWIN and XLZD, together with upcoming cLFV searches (in particular the future sensitivity of μ → 3e and μ → e conversion experiments), will be capable of testing substantial regions of the parameter space, including those associated with low reheating temperatures.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"2 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358771","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}
Pub Date : 2026-03-05DOI: 10.1088/1475-7516/2026/03/012
Payaswinee Arvikar, Sakshi Gautam, Anagh Venneti and Sarmistha Banik
We perform a comparative Bayesian analysis of fermionic and bosonic dark matter admixed neutron stars (DMANS) by incorporating a comprehensive set of theoretical, experimental, and astrophysical constraints. The hadronic matter equation of state (EoS) is modeled using a relativistic mean-field approach, constrained by chiral effective field theory (χEFT) calculations at low densities, finite nuclei and heavy-ion collision data at intermediate densities, and neutron star (NS) observations at high densities. For the dark sector, we consider fermionic dark matter (FDM) interacting via a dark vector meson, and two bosonic dark matter models (BDM1 and BDM2) characterized by self-interacting scalar fields. Bayesian inference is employed to constrain the model parameters, including the dark matter mass, coupling strength, and dark matter fraction within NSs. Our analysis finds that all models yield consistent nuclear matter parameters, allowing a small dark matter fraction under 10%. The presence of dark matter slightly softens the EoS, leading to a modest reduction in NS mass, radius, and tidal deformability, though all models remain compatible with NICER and GW170817 observations. The log-evidence and likelihood analyses reveal no statistical preference among the FDM and BDM models, indicating that current astrophysical data cannot decisively distinguish between fermionic and bosonic dark matter scenarios. This study provides a unified statistical framework to constrain dark matter properties using NS observables.
{"title":"Fermionic versus Bosonic Dark Matter in Neutron Stars: A bayesian study with multi-density constraints","authors":"Payaswinee Arvikar, Sakshi Gautam, Anagh Venneti and Sarmistha Banik","doi":"10.1088/1475-7516/2026/03/012","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/03/012","url":null,"abstract":"We perform a comparative Bayesian analysis of fermionic and bosonic dark matter admixed neutron stars (DMANS) by incorporating a comprehensive set of theoretical, experimental, and astrophysical constraints. The hadronic matter equation of state (EoS) is modeled using a relativistic mean-field approach, constrained by chiral effective field theory (χEFT) calculations at low densities, finite nuclei and heavy-ion collision data at intermediate densities, and neutron star (NS) observations at high densities. For the dark sector, we consider fermionic dark matter (FDM) interacting via a dark vector meson, and two bosonic dark matter models (BDM1 and BDM2) characterized by self-interacting scalar fields. Bayesian inference is employed to constrain the model parameters, including the dark matter mass, coupling strength, and dark matter fraction within NSs. Our analysis finds that all models yield consistent nuclear matter parameters, allowing a small dark matter fraction under 10%. The presence of dark matter slightly softens the EoS, leading to a modest reduction in NS mass, radius, and tidal deformability, though all models remain compatible with NICER and GW170817 observations. The log-evidence and likelihood analyses reveal no statistical preference among the FDM and BDM models, indicating that current astrophysical data cannot decisively distinguish between fermionic and bosonic dark matter scenarios. This study provides a unified statistical framework to constrain dark matter properties using NS observables.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358769","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}
Pub Date : 2026-03-05DOI: 10.1088/1475-7516/2026/03/011
Saptarshi Sarkar and Tirthankar Roy Choudhury
Constraining the Epoch of Reionization (EoR) with physically motivated simulations is hampered by the high cost of conventional parameter inference. We present an efficient emulator-based framework that dramatically reduces this bottleneck for the photon-conserving semi-numerical code SCRIPT. Our approach combines (i) a reliable coarse-resolution MCMC to locate the high-likelihood region (exploiting the large-scale convergence of SCRIPT) with (ii) an adaptive, targeted sampling strategy to build a compact high-resolution training set for an artificial neural network based emulator of the model likelihood. With only ≈ 103 high-resolution simulations, the trained emulators achieve excellent predictive accuracy (R2 ≈ 0.97–0.99) and, when embedded within an MCMC framework, reproduce posterior distributions from full high-resolution runs. Compared to conventional MCMC, our pipeline reduces the number of expensive simulations by a factor of ∼ 100 and lowers total CPU cost by up to a factor of ∼ 70, while retaining statistical fidelity. This computational speedup makes inference in much higher-dimensional models tractable (e.g., those needed to incorporate JWST and upcoming 21 cm datasets) and provides a general strategy for building efficient emulators for next generation of EoR constraints.
{"title":"Accelerating reionization constraints: An ANN-emulator framework for the SCRIPT Semi-numerical Model","authors":"Saptarshi Sarkar and Tirthankar Roy Choudhury","doi":"10.1088/1475-7516/2026/03/011","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/03/011","url":null,"abstract":"Constraining the Epoch of Reionization (EoR) with physically motivated simulations is hampered by the high cost of conventional parameter inference. We present an efficient emulator-based framework that dramatically reduces this bottleneck for the photon-conserving semi-numerical code SCRIPT. Our approach combines (i) a reliable coarse-resolution MCMC to locate the high-likelihood region (exploiting the large-scale convergence of SCRIPT) with (ii) an adaptive, targeted sampling strategy to build a compact high-resolution training set for an artificial neural network based emulator of the model likelihood. With only ≈ 103 high-resolution simulations, the trained emulators achieve excellent predictive accuracy (R2 ≈ 0.97–0.99) and, when embedded within an MCMC framework, reproduce posterior distributions from full high-resolution runs. Compared to conventional MCMC, our pipeline reduces the number of expensive simulations by a factor of ∼ 100 and lowers total CPU cost by up to a factor of ∼ 70, while retaining statistical fidelity. This computational speedup makes inference in much higher-dimensional models tractable (e.g., those needed to incorporate JWST and upcoming 21 cm datasets) and provides a general strategy for building efficient emulators for next generation of EoR constraints.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"48 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358880","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}
Pub Date : 2026-03-05DOI: 10.1088/1475-7516/2026/03/008
Qi Lai, Qing-Yu Lan, Hao-Yang Liu, Yu-Tong Wang and Yun-Song Piao
A particularly compelling aspect of the GW190521 event detected by the LIGO-Virgo-KAGRA (LVK) collaboration is that it has an extremely short duration, and lacks a clearly identifiable inspiral phase usually observed in the binary black holes (BBHs) coalescence. In this work, we hypothesize that GW190521 might represent a single, isolated gravitational wave (GW) echo pulse from the wormhole, which is the postmerger remnant of BBHs in another universe and connected to our universe through a throat. The ringdown signal after BBHs merged in another universe can pass through the throat of wormhole and be detected in our universe as a short-duration echo pulse. Our analysis results indicate that our model yields a network signal-to-noise ratio comparable to that of the standard BBHs merger model reported by the LVK collaboration. For GW190521, Bayesian model selection yields ln ℬEchoBBH ≃ -2.9, indicating that the data favor the BBH hypothesis over our echo-for-wormhole model.
{"title":"Is GW190521 a gravitational wave echo of wormhole remnant from another universe?","authors":"Qi Lai, Qing-Yu Lan, Hao-Yang Liu, Yu-Tong Wang and Yun-Song Piao","doi":"10.1088/1475-7516/2026/03/008","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/03/008","url":null,"abstract":"A particularly compelling aspect of the GW190521 event detected by the LIGO-Virgo-KAGRA (LVK) collaboration is that it has an extremely short duration, and lacks a clearly identifiable inspiral phase usually observed in the binary black holes (BBHs) coalescence. In this work, we hypothesize that GW190521 might represent a single, isolated gravitational wave (GW) echo pulse from the wormhole, which is the postmerger remnant of BBHs in another universe and connected to our universe through a throat. The ringdown signal after BBHs merged in another universe can pass through the throat of wormhole and be detected in our universe as a short-duration echo pulse. Our analysis results indicate that our model yields a network signal-to-noise ratio comparable to that of the standard BBHs merger model reported by the LVK collaboration. For GW190521, Bayesian model selection yields ln ℬEchoBBH ≃ -2.9, indicating that the data favor the BBH hypothesis over our echo-for-wormhole model.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"68 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358766","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}
Pub Date : 2026-03-05DOI: 10.1088/1475-7516/2026/03/009
Alexandre M. Pombo and Lorenzo Pizzuti
We introduce SpectralPINN, a hybrid pseudo-spectral/physics-informed neural network (PINN) solver for Kerr quasinormal modes that targets the Teukolsky equation in both the separated (radial/angular) and joint two-dimensional formulations. The solver replaces standard neural activation functions with Chebyshev polynomials of the first kind and supports both soft — via loss penalties — and hard — enforced by analytic masks — implementations of Leaver's normalization. Benchmarking against Leaver's continued-fraction method shows cumulative (real+imaginary part) relative frequency errors of ∼ 0.001% for the separated formulation with hard normalization, ∼ 0.1% for both the soft separated and soft joint formulations, and ∼ 0.01% for the hard joint case. Exploiting our ability to solve the joint equation, we add a small quadrupolar perturbation to the Teukolsky operator, effectively rendering the problem non-separable. The resulting perturbed quasinormal modes are compared against the expected precision of the Einstein Telescope, allowing us to constrain the magnitude of the perturbation. These proof-of-concept results demonstrate that hybrid spectral-PINN solvers can provide a flexible pathway to quasinormal spectra in settings where separability, asymptotics, or field content become more intricate and high accuracy is required.
{"title":"Teukolsky by design: A hybrid spectral-PINN solver for Kerr quasinormal modes","authors":"Alexandre M. Pombo and Lorenzo Pizzuti","doi":"10.1088/1475-7516/2026/03/009","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/03/009","url":null,"abstract":"We introduce SpectralPINN, a hybrid pseudo-spectral/physics-informed neural network (PINN) solver for Kerr quasinormal modes that targets the Teukolsky equation in both the separated (radial/angular) and joint two-dimensional formulations. The solver replaces standard neural activation functions with Chebyshev polynomials of the first kind and supports both soft — via loss penalties — and hard — enforced by analytic masks — implementations of Leaver's normalization. Benchmarking against Leaver's continued-fraction method shows cumulative (real+imaginary part) relative frequency errors of ∼ 0.001% for the separated formulation with hard normalization, ∼ 0.1% for both the soft separated and soft joint formulations, and ∼ 0.01% for the hard joint case. Exploiting our ability to solve the joint equation, we add a small quadrupolar perturbation to the Teukolsky operator, effectively rendering the problem non-separable. The resulting perturbed quasinormal modes are compared against the expected precision of the Einstein Telescope, allowing us to constrain the magnitude of the perturbation. These proof-of-concept results demonstrate that hybrid spectral-PINN solvers can provide a flexible pathway to quasinormal spectra in settings where separability, asymptotics, or field content become more intricate and high accuracy is required.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"44 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358767","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}
Pub Date : 2026-03-05DOI: 10.1088/1475-7516/2026/03/007
Michael M. Wyatt, Steven R. Furlanetto and Mary H. Minasyan
Recent measurements of the mean free path (MFP) of ionizing photons at z = 6 find that it is significantly shorter than extrapolations from lower redshifts. This has a substantial impact on the topology of reionization and thus the prospects of tomography of the 21 cm signal from upcoming radio interferometers. In this work we develop the first analytic model of reionization which explicitly incorporates the MFP as a free parameter, allowing us to transparently explore its effect on the process. Our model is based on the excursion set formalism with an ionization condition which accounts for absorptions parameterized through the MFP. With the goal of direct observational comparison, we also include additional modifications which make our model particularly suitable for predicting one-point statistics of the ionization field (and 21 cm signal), which are among the fundamental quantities for tomography. We find that the effect of the MFP is much more significant during the later stages of reionization, and that including a shorter MFP reduces the size of Hii regions by around an order of magnitude towards the end of reionization compared with analytic models which do not account for the MFP. We find that the reported MFP value produces a contrast in the 21 cm signal of 𝒪(1 mK) or less at resolutions θ ∼ 15–35 arcmin, an order of magnitude below naive estimates and up to a factor of several smaller than when using a larger MFP value extrapolated from low redshift, requiring significantly more sensitivity for imaging. We compare the contrast to noise estimates for arrays similar in size to HERA and the first phase SKA-Low and find that SKA has sufficient sensitivity for direct imaging (at the largest scales considered), while the predicted signal will be challenging for arrays similar in size to HERA. Our model indicates that more detailed sensitivity estimates are warranted in the context of a shorter MFP.
最近对z = 6处电离光子的平均自由程（MFP）的测量发现，它明显短于低红移的外推。这对再电离的拓扑结构产生了实质性的影响，从而对即将到来的无线电干涉仪的21厘米信号的层析成像前景产生了实质性的影响。在这项工作中，我们开发了第一个再电离分析模型，该模型明确地将MFP作为自由参数，使我们能够透明地探索其对过程的影响。我们的模型是基于偏移集的形式，并考虑了通过MFP参数化的吸收的电离条件。为了进行直接观测比较，我们还进行了额外的修改，使我们的模型特别适合于预测电离场（和21厘米信号）的一点统计量，这是断层扫描的基本量之一。我们发现，在再电离的后期阶段，MFP的影响更为显著，与不考虑MFP的分析模型相比，包括较短的MFP，在再电离结束时，Hii区域的大小减少了大约一个数量级。我们发现，在分辨率θ ~ 15-35 arcmin下，报告的MFP值在21 cm （1 mK）或更小的信号中产生对比度，比原始估计低一个数量级，并且比使用从低红移推断的更大的MFP值时小几个因子，需要显着更高的成像灵敏度。我们将其与与HERA和第一阶段SKA- low大小相似的阵列的噪声估计进行对比，发现SKA具有足够的直接成像灵敏度（在考虑的最大尺度下），而预测的信号对于与HERA大小相似的阵列将具有挑战性。我们的模型表明，在较短的MFP背景下，更详细的灵敏度估计是有保证的。
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