{"title":"The nonlinear tails in black hole ringdown: the scattering perspective","authors":"A. Ianniccari, L. Lo Bianco and A. Riotto","doi":"10.1088/1475-7516/2025/10/062","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/062","url":null,"abstract":"Black holes regain their static configuration by emitting ringdown gravitational waves, whose amplitude decays in time following a power law at fixed spatial positions. We show that the nonlinear decay power law may be obtained by simple scattering calculations using the in-in formalism and argue that the nonperturbative law should be t-2ℓ-1, where ℓ is the multipole of the propagating spherical gravitational wave.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"25 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145289389","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":"Graviton-photon conversion in blazar jets as a probe of high-frequency gravitational waves","authors":"Himeka Matsuo and Asuka Ito","doi":"10.1088/1475-7516/2025/10/061","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/061","url":null,"abstract":"We study graviton-photon conversion in the magnetic fields of a blazar jet and explore the possibility of detecting high-frequency gravitational waves through blazar observations. We calculate the conversion rate using the magnetic field configurations of leptonic, lepto-hadronic, and hadronic one-zone synchrotron self-Compton models for the blazar jet of Mrk 501. By requiring that the photon flux produced within the blazar jet does not exceed the observed flux of Mrk 501, we derive conservative constraints on the abundance of stochastic gravitational waves. We find that, for all three models considered, the resulting limits can be more stringent than previous constraints in the frequency range from 108 Hz to 1015 Hz.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"23 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145289257","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":"Can we hear beats with pulsar timing arrays?","authors":"Shun Yamamoto and Hideki Asada","doi":"10.1088/1475-7516/2025/10/058","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/058","url":null,"abstract":"An isolated supermassive black hole binary (SMBHB) produces an identical cross-correlation pattern of pulsar timings as an isotropic stochastic background gravitational waves (GWs) generated possibly by inflation. Can there remain the identical cross-correlation pattern in the presence of a secondary SMBHB? To address this issue, the present paper focuses on GWs with similar amplitudes but slightly different frequencies f1 and f2 coming from two different directions. Beats between the two GWs can modify angular correlation patterns. The beat-induced correlation patterns are not stationary but modulated with a beat frequency fbeat ≡ |f1 - f2|. We obtain an analytic solution that allows us to infer fbeat from the modulated angular correlations.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"108 2 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145289255","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":"Numerical treatment of annual modulation of relic neutrinos","authors":"Fabian Zimmer and Shin'ichiro Ando","doi":"10.1088/1475-7516/2025/10/059","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/059","url":null,"abstract":"We present a numerical treatment of the annual modulation of relic neutrinos due to the Sun's gravitational influence. Extending our previously developed N-1-body simulation framework from Milky Way scales to solar system dynamics, we model how cosmic neutrino background densities might vary throughout Earth's orbital cycle. We validate our numerical approach against analytical expectations from previous studies that assumed idealized relic neutrino populations. Our results suggest that the prior gravitational history of neutrinos traversing asymmetric dark matter distributions can affect annual modulation patterns. While our simulations reproduce modulation amplitudes similar to analytical predictions for heavier neutrinos, we find that the amplitude can vary considerably depending on the specific morphology of dark matter halos. These findings highlight the importance of incorporating realistic structure formation effects when predicting potential observational relic neutrino signatures.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"20 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145289132","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}
Shyam Balaji, João Gonçalves, Danny Marfatia, António P. Morais and Roman Pasechnik
{"title":"Primordial black holes and magnetic fields in conformal neutrino mass models","authors":"Shyam Balaji, João Gonçalves, Danny Marfatia, António P. Morais and Roman Pasechnik","doi":"10.1088/1475-7516/2025/10/064","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/064","url":null,"abstract":"Sufficiently strong and long-lasting first-order phase transitions can produce primordial black holes (PBHs) that contribute substantially to the dark matter abundance of the Universe, and can produce large-scale primordial magnetic fields. We study these mechanisms in a generic class of conformal U(1)' models that also explain active neutrino oscillation data via the type-I seesaw mechanism. We find that phase transitions that occur at seesaw scales between 104 GeV and 1011 GeV produce gravitational wave signals (from the dynamics of the phase transition and from the decay of cosmic string loops) at LISA/ET that can be correlated with microlensing signals of PBHs at the Roman Space Telescope, while scales near 1011 GeV can be correlated with Hawking evaporation signals at future gamma-ray telescopes. LISA can probe the entire range of PBH masses between 1 × 10-16M⊙ and 8 × 10-11M⊙ if PBHs fully account for the dark matter abundance. For Z' masses between 40 TeV and 104 TeV, and 10 TeV right-handed neutrinos, helical magnetic fields can be produced with magnitudes ≳ 0.5 pG and coherence lengths ≳ 0.008 Mpc, above current blazar lower bounds.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"154 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145289391","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}
Nathan Cruickshank, Robert Crittenden, Kazuya Koyama and Marco Bruni
{"title":"Forecasts for interacting dark energy with time-dependent momentum exchange","authors":"Nathan Cruickshank, Robert Crittenden, Kazuya Koyama and Marco Bruni","doi":"10.1088/1475-7516/2025/10/052","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/052","url":null,"abstract":"Models of interacting dark energy and dark matter offer a possible solution to cosmological tensions. In this work, we examine a pure momentum-exchange model with a time-dependent coupling strength ξ(z) that could help to alleviate the S8 tension. We perform Fisher forecasting and MCMC analysis to constrain the coupling strength of this interaction for different redshift bins 0.0 < z < 2.1, using the specifications of upcoming DESI-like surveys. For this analysis, we examine both a model with a constant equation of state w = -0.9, as well as a thawing dark energy model with an evolving w(z). We show that, for a constant equation of state, ξ(z) can be well constrained in all redshift bins. However, due to a weaker effect at early times, the constraints are significantly reduced at high redshifts in the case of a thawing w(z) model.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"4 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282903","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}
Chad Popik, Nicholas Battaglia, Aleksandra Kusiak, Boris Bolliet and J. Colin Hill
{"title":"On the impacts of halo model implementations in Sunyaev-Zeldovich cross-correlation analyses","authors":"Chad Popik, Nicholas Battaglia, Aleksandra Kusiak, Boris Bolliet and J. Colin Hill","doi":"10.1088/1475-7516/2025/10/051","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/051","url":null,"abstract":"Statistical studies of the circumgalactic medium (CGM) using Sunyaev-Zeldovich (SZ) observations offer a promising method of studying the gas properties of galaxies and the astrophysics that govern their evolution. Forward modeling profiles from theory and simulations allows them to be refined directly off of data, but there are currently significant differences between the thermal SZ (tSZ) observations of the CGM and the predicted tSZ signal. While these discrepancies could be real, they could also be the result of decisions in the forward modeling used to build statistical measures from theory. In order to see effects of this, we compare an analysis utilizing halo occupancy distributions (HODs) implemented in halo models to simulate the galaxy distribution against previous studies, which weighted their results to match the CMASS galaxy sample, which contains nearly one million galaxies, mainly centrals of group-sized halos, selected for relatively uniform stellar mass across redshifts between 0.4 < z < 0.7. We review some of the implementation differences that can account for changes, such as miscentering, one-halo/two-halo cutoff radii, and mass ranges, all of which will need to be given the proper attention in future high-signal-to-noise studies. We find that our more thorough model predicts a signal with a 33% improved fit than the one from previous studies on the exact same sample. Additionally, we find that modifications that change the satellite fraction even by just a few percent, such as editing the halo mass range and certain HOD parameters, result in strong changes in the final signal. Although significant, this discrepancy from the modeling choices is not large enough to completely account for the existing disagreements between simulations and measurements.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"38 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282904","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":"Quasinormal modes from EFT of black hole perturbations in vector-tensor gravity","authors":"Shogo Tomizuka, Hajime Kobayashi, Naritaka Oshita, Kazufumi Takahashi and Shinji Mukohyama","doi":"10.1088/1475-7516/2025/10/056","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/056","url":null,"abstract":"We study the dynamics of odd-parity perturbations on a static and spherically symmetric black hole background with a timelike vector field based on the effective field theory (EFT) approach. We derive the quadratic Lagrangian written in terms of two master variables, corresponding to the tensor and vector gravitons, which are coupled in general, while they can be decoupled on a stealth Schwarzschild(-de Sitter) background. For the stealth Schwarzschild background, we find that the quasinormal mode frequencies for both degrees of freedom are obtained from those in general relativity by simple scaling. Nonetheless, due to the fact that the metric perturbation is a non-trivial linear combination of the two degrees of freedom with different QNM spectra, the ringdown gravitational waves may exhibit characteristic modulation that can in principle be a signature of vector-tensor gravity.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"26 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282942","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}
Partha Kumar Paul, Sujit Kumar Sahoo and Narendra Sahu
{"title":"Anatomy of singlet-doublet dark matter relic: annihilation, co-annihilation, co-scattering, and freeze-in","authors":"Partha Kumar Paul, Sujit Kumar Sahoo and Narendra Sahu","doi":"10.1088/1475-7516/2025/10/053","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/053","url":null,"abstract":"The singlet-doublet vector-like fermion dark matter model has been extensively studied in the literature over the past decade. An important parameter in this model is the singlet-doublet mixing angle (sinθ). All the previous studies have primarily focused on annihilation and co-annihilation processes for obtaining the correct dark matter relic density, assuming that the singlet and doublet components decouple at the same epoch. In this work, we demonstrate that this assumption holds only for larger mixing angles with a dependency on the mass of the dark matter. However, it badly fails for the mixing angle sinθ < 0.05. We present a systematic study of the parameter space of the singlet-doublet dark matter relic, incorporating annihilation, co-annihilation, and, for the first time, co-scattering processes. Additionally, non-thermal productions via the freeze-in and SuperWIMP mechanism are also explored. We found that due to the inclusion of co-scattering processes, the correct relic density parameter space is shifted towards the detection sensitivity range of the LHC and MATHUSLA via displaced vertex signatures.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"6 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282938","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}
Anirban Dasgupta, Nishant Tiwari and Indrani Banerjee
{"title":"Signatures of Einstein-Maxwell dilaton-axion gravity from the observed quasi-periodic oscillations in black holes","authors":"Anirban Dasgupta, Nishant Tiwari and Indrani Banerjee","doi":"10.1088/1475-7516/2025/10/054","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/10/054","url":null,"abstract":"String-inspired models are often believed to provide an interesting framework for quantum gravity and force unification with promising prospects to resolve issues like dark matter and dark energy, which cannot be satisfactorily incorporated within the framework of general relativity (GR). The goal of the present work is to investigate the role of the Einstein-Maxwell dilaton-axion (EMDA) gravity arising in the low-energy effective action of the heterotic string theory in explaining astrophysical observations, in particular, the high-frequency quasi-periodic oscillations (HFQPOs) observed in the power spectrum of black holes. EMDA gravity has interesting cosmological implications, and hence it is worthwhile to explore the footprints of such a theory in available astrophysical observations. This requires one to study the stationary, axi-symmetric black hole solution in EMDA gravity, which corresponds to the Kerr-Sen spacetime. Such black holes are endowed with a dilatonic charge while the rotation is sourced from the axionic field. We investigate the orbital and epicyclic frequencies of matter rotating in the Kerr-Sen spacetime and consider eleven well-studied QPO models in this work. We compare the model-dependent QPO frequencies with the available observations of five BH sources, namely, XTE J1550-564, GRS 1915+105, H 143+322, GRO J1655-40 and Sgr A*. Our analysis provides constraints on the spins of the aforesaid black holes which, when compared with previous estimates, enables us to understand the observationally favored QPO models for each of these sources. Further, from the current data, the EMDA scenario cannot be ruled out in favor of general relativity. We comment on the implications and limitations of our findings and how the present constrains compare with the existing literature.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282939","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}