Pub Date : 2025-01-10DOI: 10.1088/1475-7516/2025/01/050
Matthew Elley, Josu C. Aurrekoetxea, Katy Clough, Raphael Flauger, Panagiotis Giannadakis and Eugene A. Lim
We investigate the effects of large inhomogeneities in both the inflaton field and its momentum. We find that in general, large kinetic perturbations reduce the number of e-folds of inflation. In particular, we observe that inflationary models with sub-Planckian characteristic scales are not robust even to kinetic energy densities that are sub-dominant to the potential energy density, unless the initial field configuration is sufficiently far from the minimum. This strengthens the results of our previous work. In inflationary models with super-Planckian characteristic scales, despite a reduction in the number of e-folds, inflation is robust even when the potential energy density is initially sub-dominant. For the cases we study, the robustness of inflation strongly depends on whether the inflaton field is driven into the reheating phase by the inhomogeneous scalar dynamics.
{"title":"Robustness of inflation to kinetic inhomogeneities","authors":"Matthew Elley, Josu C. Aurrekoetxea, Katy Clough, Raphael Flauger, Panagiotis Giannadakis and Eugene A. Lim","doi":"10.1088/1475-7516/2025/01/050","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/050","url":null,"abstract":"We investigate the effects of large inhomogeneities in both the inflaton field and its momentum. We find that in general, large kinetic perturbations reduce the number of e-folds of inflation. In particular, we observe that inflationary models with sub-Planckian characteristic scales are not robust even to kinetic energy densities that are sub-dominant to the potential energy density, unless the initial field configuration is sufficiently far from the minimum. This strengthens the results of our previous work. In inflationary models with super-Planckian characteristic scales, despite a reduction in the number of e-folds, inflation is robust even when the potential energy density is initially sub-dominant. For the cases we study, the robustness of inflation strongly depends on whether the inflaton field is driven into the reheating phase by the inhomogeneous scalar dynamics.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"13 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939809","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 : 2025-01-10DOI: 10.1088/1475-7516/2025/01/043
Ø. Christiansen, F. Hassani and D.F. Mota
A new degravitation mechanism within the framework of scalar tensor gravity is postulated and included by prescription. The mechanism eliminates all constant contributions from the potential to the Friedmann equation, leaving only the kinematic and the dynamic terms of the potential to drive cosmic acceleration. We explore a scenario involving a density-triggered phase transition in the late-time universe, and argue that the resulting effective energy density and equation of state parameter can explain late-time cosmology when extrapolated to a region of the parameter space.
{"title":"Environmental cosmic acceleration from a phase transition in the dark sector","authors":"Ø. Christiansen, F. Hassani and D.F. Mota","doi":"10.1088/1475-7516/2025/01/043","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/043","url":null,"abstract":"A new degravitation mechanism within the framework of scalar tensor gravity is postulated and included by prescription. The mechanism eliminates all constant contributions from the potential to the Friedmann equation, leaving only the kinematic and the dynamic terms of the potential to drive cosmic acceleration. We explore a scenario involving a density-triggered phase transition in the late-time universe, and argue that the resulting effective energy density and equation of state parameter can explain late-time cosmology when extrapolated to a region of the parameter space.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"35 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939802","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 : 2025-01-10DOI: 10.1088/1475-7516/2025/01/045
Adriana Nadal-Matosas, Héctor Gil-Marín and Licia Verde
We study the robustness of the Baryon Acoustic Oscillation (BAO) feature in the large-scale structure in the presence of massive neutrinos. In the standard BAO analysis pipeline a reference cosmological model is assumed to boost the BAO peak through the so-called reconstruction technique and in the modelling of the BAO feature to extract the cosmological information. State-of-the art spectroscopic BAO measurements, such as the Dark Energy Spectroscopic Instrument claim an aggregate precision of 0.52% on the BAO scale, with a systematic error of 0.1% associated to the assumption of a reference cosmology when measuring and analyzing the BAO feature. While the systematic effect induced by this arbitrary choice of fiducial cosmology has been studied for a wide range of ΛCDM-like models, it has not yet been tested for reference cosmologies with massive neutrinos with the precision afforded by next generation surveys. In this context, we employ the Quijote high-resolution dark-matter simulations with haloes above a mass of M ∼ 2×1013h-1M⊙, with different values for the total sum of neutrinos masses, ∑mν [eV] = 0, 0.1, 0,2, 0.4 to study and quantify the impact of the pipeline's built-in assumption of massless neutrinos on the measurement of the BAO signal, with a special focus on the BAO reconstruction technique. We determine that any additional systematic bias introduced by the assumption of massless neutrinos is no greater than 0.1% (0.2%) for the isotropic (anisotropic) measurement. We expect these conclusions also hold for galaxies provided that neutrino properties do not alter the galaxy-halo connection.
{"title":"Testing the robustness of the BAO determination in the presence of massive neutrinos","authors":"Adriana Nadal-Matosas, Héctor Gil-Marín and Licia Verde","doi":"10.1088/1475-7516/2025/01/045","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/045","url":null,"abstract":"We study the robustness of the Baryon Acoustic Oscillation (BAO) feature in the large-scale structure in the presence of massive neutrinos. In the standard BAO analysis pipeline a reference cosmological model is assumed to boost the BAO peak through the so-called reconstruction technique and in the modelling of the BAO feature to extract the cosmological information. State-of-the art spectroscopic BAO measurements, such as the Dark Energy Spectroscopic Instrument claim an aggregate precision of 0.52% on the BAO scale, with a systematic error of 0.1% associated to the assumption of a reference cosmology when measuring and analyzing the BAO feature. While the systematic effect induced by this arbitrary choice of fiducial cosmology has been studied for a wide range of ΛCDM-like models, it has not yet been tested for reference cosmologies with massive neutrinos with the precision afforded by next generation surveys. In this context, we employ the Quijote high-resolution dark-matter simulations with haloes above a mass of M ∼ 2×1013h-1M⊙, with different values for the total sum of neutrinos masses, ∑mν [eV] = 0, 0.1, 0,2, 0.4 to study and quantify the impact of the pipeline's built-in assumption of massless neutrinos on the measurement of the BAO signal, with a special focus on the BAO reconstruction technique. We determine that any additional systematic bias introduced by the assumption of massless neutrinos is no greater than 0.1% (0.2%) for the isotropic (anisotropic) measurement. We expect these conclusions also hold for galaxies provided that neutrino properties do not alter the galaxy-halo connection.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"24 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939804","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 : 2025-01-10DOI: 10.1088/1475-7516/2025/01/049
Samy Kaci and Gwenael Giacinti
We present our new model for the description of the very high energy Galactic gamma-ray emission based on a discrete injection of cosmic rays by individual sources. We investigate the morphology of the very high energy gamma-ray sky, the detectability of cosmic-ray sources and the clumpiness of the diffuse gamma-ray flux, assuming two different scenarios for cosmic-ray propagation. Namely, a standard isotropic and homogeneous diffusion process and an isotropic and inhomogeneous diffusion process. We notably formulate a possible explanation to the small number of hadronic PeVatrons recently detected by LHAASO. In the case of the inhomogeneous diffusion process, we constrain the number of hadronic PeVatrons to be small. Finally, we give an argument that may explain the discrepancy between the interstellar gas density distribution and the very high energy diffuse gamma-ray flux.
{"title":"Imprints of PeV cosmic-ray sources on the diffuse gamma-ray emission","authors":"Samy Kaci and Gwenael Giacinti","doi":"10.1088/1475-7516/2025/01/049","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/049","url":null,"abstract":"We present our new model for the description of the very high energy Galactic gamma-ray emission based on a discrete injection of cosmic rays by individual sources. We investigate the morphology of the very high energy gamma-ray sky, the detectability of cosmic-ray sources and the clumpiness of the diffuse gamma-ray flux, assuming two different scenarios for cosmic-ray propagation. Namely, a standard isotropic and homogeneous diffusion process and an isotropic and inhomogeneous diffusion process. We notably formulate a possible explanation to the small number of hadronic PeVatrons recently detected by LHAASO. In the case of the inhomogeneous diffusion process, we constrain the number of hadronic PeVatrons to be small. Finally, we give an argument that may explain the discrepancy between the interstellar gas density distribution and the very high energy diffuse gamma-ray flux.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"24 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939808","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 : 2025-01-10DOI: 10.1088/1475-7516/2025/01/047
Kwang Sik Jeong, Ju Hyeong Kang and Shota Nakagawa
By coupling to both the Higgs and electroweak gauge sectors, an axion can generate the matter-antimatter asymmetry in the universe via electroweak baryogenesis when the axion decay constant lies within the range of approximately 105 and 107 GeV, corresponding to axion masses between the MeV and GeV scales. In this work, we explore the intriguing possibility that the axion interacts with a dark sector, particularly with dark photons through anomalous couplings. Notably, axion-coupled dark photons can play multiple roles, including (i) suppressing the branching ratio of axion decay to Standard Model (SM) particles, which would otherwise conflict with the constraints from supernovae explosions, Big Bang nucleosynthesis, and neutron star merger events, (ii) serving as a candidate for cold dark matter if they are massive and stable, and (iii) contributing to dark radiation if they are ultralight. The axion decouples from the SM thermal bath when it becomes non-relativistic, facilitating the production of dark matter dark photons through the freeze-in mechanism, while dark radiation dark photons are thermally generated prior to the electroweak phase transition.
{"title":"Cosmological roles of dark photons in axion-induced electroweak baryogenesis","authors":"Kwang Sik Jeong, Ju Hyeong Kang and Shota Nakagawa","doi":"10.1088/1475-7516/2025/01/047","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/047","url":null,"abstract":"By coupling to both the Higgs and electroweak gauge sectors, an axion can generate the matter-antimatter asymmetry in the universe via electroweak baryogenesis when the axion decay constant lies within the range of approximately 105 and 107 GeV, corresponding to axion masses between the MeV and GeV scales. In this work, we explore the intriguing possibility that the axion interacts with a dark sector, particularly with dark photons through anomalous couplings. Notably, axion-coupled dark photons can play multiple roles, including (i) suppressing the branching ratio of axion decay to Standard Model (SM) particles, which would otherwise conflict with the constraints from supernovae explosions, Big Bang nucleosynthesis, and neutron star merger events, (ii) serving as a candidate for cold dark matter if they are massive and stable, and (iii) contributing to dark radiation if they are ultralight. The axion decouples from the SM thermal bath when it becomes non-relativistic, facilitating the production of dark matter dark photons through the freeze-in mechanism, while dark radiation dark photons are thermally generated prior to the electroweak phase transition.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"82 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939807","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 : 2025-01-10DOI: 10.1088/1475-7516/2025/01/044
Lavinia Heisenberg, Henri Inchauspé and David Maibach
We propose a diagnostic tool for future analyses of stochastic gravitational wave background signals of extra-galactic origin in LISA data. Next-generation gravitational wave detectors hold the capability to track unresolved gravitational waves bundled into a stochastic background. This composite background contains cosmological and astrophysical contributions, the exploration of which offers promising avenues for groundbreaking new insights into very early universe cosmology as well as late-time structure formation. In this article, we develop a full end-to-end pipeline for the extraction of extra-galactic signals, based on kinematic anisotropies arising from the galactic motion, via full-time-domain simulations of LISA's response to the gravitational wave anisotropic sky. Employing a Markov-Chain-Monte-Carlo map-making scheme, multipoles up to ℓ=2 are recovered for scale-free spectra in the case of a high signal-to-noise ratio. We demonstrate that our analysis is consistently beating sample variance and is robust against statistical and systematic errors. The impact of instrumental noise on the extraction of kinematic anisotropies is investigated, and we establish a detection threshold of ΩGW ≳ 5 × 10-8 in the presence of instrument-induced noise. Potential avenues for improvement in our methodology are highlighted.
{"title":"Observing kinematic anisotropies of the stochastic background with LISA","authors":"Lavinia Heisenberg, Henri Inchauspé and David Maibach","doi":"10.1088/1475-7516/2025/01/044","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/044","url":null,"abstract":"We propose a diagnostic tool for future analyses of stochastic gravitational wave background signals of extra-galactic origin in LISA data. Next-generation gravitational wave detectors hold the capability to track unresolved gravitational waves bundled into a stochastic background. This composite background contains cosmological and astrophysical contributions, the exploration of which offers promising avenues for groundbreaking new insights into very early universe cosmology as well as late-time structure formation. In this article, we develop a full end-to-end pipeline for the extraction of extra-galactic signals, based on kinematic anisotropies arising from the galactic motion, via full-time-domain simulations of LISA's response to the gravitational wave anisotropic sky. Employing a Markov-Chain-Monte-Carlo map-making scheme, multipoles up to ℓ=2 are recovered for scale-free spectra in the case of a high signal-to-noise ratio. We demonstrate that our analysis is consistently beating sample variance and is robust against statistical and systematic errors. The impact of instrumental noise on the extraction of kinematic anisotropies is investigated, and we establish a detection threshold of ΩGW ≳ 5 × 10-8 in the presence of instrument-induced noise. Potential avenues for improvement in our methodology are highlighted.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"28 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939803","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 : 2025-01-09DOI: 10.1088/1475-7516/2025/01/030
Ben-Yang Zhu, Xiaoyuan Huang and Peng-Fei Yin
High energy photons originating from the Galactic Center (GC) region have the potential to undergo significant photon-axion-like particle (ALP) oscillation effects, primarily induced by the presence of intense magnetic fields in this region. Observations conducted by imaging atmospheric Cherenkov telescopes have detected very high energy gamma-rays originating from a point source known as HESS J1745-290, situated in close proximity to the GC. This source is conjectured to be associated with the supermassive black hole Sagittarius A*. The GC region contains diverse structures, including molecular clouds and non-thermal filaments, which collectively contribute to the intricate magnetic field configurations in this region. By utilizing a magnetic field model specific in the GC region, we explore the phenomenon of photon-ALP oscillations in the gamma-ray spectrum of HESS J1745-290. Our analysis does not reveal any discernible signature of photon-ALP oscillations, yielding significant constraints that serve as a complement to gamma-ray observations of extragalactic sources across a broad parameter region. The uncertainties arising from the outer Galactic magnetic field models have minor impacts on our results, except for ALP masses around 10-7 eV, as the dominant influence originates from the intense magnetic field strength in the inner GC region.
{"title":"Constraints on axion-like particles from the gamma-ray observation of the Galactic Center","authors":"Ben-Yang Zhu, Xiaoyuan Huang and Peng-Fei Yin","doi":"10.1088/1475-7516/2025/01/030","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/030","url":null,"abstract":"High energy photons originating from the Galactic Center (GC) region have the potential to undergo significant photon-axion-like particle (ALP) oscillation effects, primarily induced by the presence of intense magnetic fields in this region. Observations conducted by imaging atmospheric Cherenkov telescopes have detected very high energy gamma-rays originating from a point source known as HESS J1745-290, situated in close proximity to the GC. This source is conjectured to be associated with the supermassive black hole Sagittarius A*. The GC region contains diverse structures, including molecular clouds and non-thermal filaments, which collectively contribute to the intricate magnetic field configurations in this region. By utilizing a magnetic field model specific in the GC region, we explore the phenomenon of photon-ALP oscillations in the gamma-ray spectrum of HESS J1745-290. Our analysis does not reveal any discernible signature of photon-ALP oscillations, yielding significant constraints that serve as a complement to gamma-ray observations of extragalactic sources across a broad parameter region. The uncertainties arising from the outer Galactic magnetic field models have minor impacts on our results, except for ALP masses around 10-7 eV, as the dominant influence originates from the intense magnetic field strength in the inner GC region.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"95 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936723","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 : 2025-01-09DOI: 10.1088/1475-7516/2025/01/042
Anita Yadav, Suresh Kumar, Cihad Kıbrıs and Özgür Akarsu
In this work, we investigate a two-parameter extension of the ΛsCDM model, as well as the ΛCDM model for comparison, by allowing variations in the effective number of neutrino species (Neff) and their total mass (∑mν). Our motivation is twofold: (i) to examine whether the ΛsCDM framework retains its success in fitting the data and addressing major cosmological tensions, without suggesting a need for a deviation from the standard model of particle physics, and (ii) to determine whether the data indicate new physics that could potentially address cosmological tensions, either in the post-recombination universe through the late-time (z ∼ 2) mirror AdS-to-dS transition feature of the ΛsCDM model, or in the pre-recombination universe through modifications in the standard values of Neff and ∑mν, or both. Within the extended ΛsCDM model, referred to as ΛsCDM+Neff+∑mν, we find no significant tension when considering the Planck-alone analysis. We observe that incorporating BAO data limits the further success of the ΛsCDM extension. However, the weakly model-dependent BAOtr data, along with Planck and Planck+PP&SH0ES, favor an H0 value of approximately 73 km s-1 Mpc-1, which aligns perfectly with local measurements. In cases where BAOtr is part of the combined dataset, the mirror AdS-dS transition is very effective in providing enhanced H0 values, and thus the model requires no significant deviation from the standard value of Neff = 3.044, remaining consistent with the standard model of particle physics. Both the H0 and S8 tensions are effectively addressed, with some compromise in the case of the Planck+BAO dataset. Finally, the upper bounds obtained on total neutrino mass, ∑mν ≲ 0.50 eV, are fully compatible with neutrino oscillation experiments. Our findings provide evidence that late-time physics beyond ΛCDM, such as ΛsCDM, without altering the standard description of the pre-recombination universe, can suffice to alleviate the major cosmological tensions, as indicated by our analysis of ΛsCDM+Neff+∑mν.
{"title":"ΛsCDM cosmology: alleviating major cosmological tensions by predicting standard neutrino properties","authors":"Anita Yadav, Suresh Kumar, Cihad Kıbrıs and Özgür Akarsu","doi":"10.1088/1475-7516/2025/01/042","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/042","url":null,"abstract":"In this work, we investigate a two-parameter extension of the ΛsCDM model, as well as the ΛCDM model for comparison, by allowing variations in the effective number of neutrino species (Neff) and their total mass (∑mν). Our motivation is twofold: (i) to examine whether the ΛsCDM framework retains its success in fitting the data and addressing major cosmological tensions, without suggesting a need for a deviation from the standard model of particle physics, and (ii) to determine whether the data indicate new physics that could potentially address cosmological tensions, either in the post-recombination universe through the late-time (z ∼ 2) mirror AdS-to-dS transition feature of the ΛsCDM model, or in the pre-recombination universe through modifications in the standard values of Neff and ∑mν, or both. Within the extended ΛsCDM model, referred to as ΛsCDM+Neff+∑mν, we find no significant tension when considering the Planck-alone analysis. We observe that incorporating BAO data limits the further success of the ΛsCDM extension. However, the weakly model-dependent BAOtr data, along with Planck and Planck+PP&SH0ES, favor an H0 value of approximately 73 km s-1 Mpc-1, which aligns perfectly with local measurements. In cases where BAOtr is part of the combined dataset, the mirror AdS-dS transition is very effective in providing enhanced H0 values, and thus the model requires no significant deviation from the standard value of Neff = 3.044, remaining consistent with the standard model of particle physics. Both the H0 and S8 tensions are effectively addressed, with some compromise in the case of the Planck+BAO dataset. Finally, the upper bounds obtained on total neutrino mass, ∑mν ≲ 0.50 eV, are fully compatible with neutrino oscillation experiments. Our findings provide evidence that late-time physics beyond ΛCDM, such as ΛsCDM, without altering the standard description of the pre-recombination universe, can suffice to alleviate the major cosmological tensions, as indicated by our analysis of ΛsCDM+Neff+∑mν.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"29 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936774","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 : 2025-01-09DOI: 10.1088/1475-7516/2025/01/031
Lin-Qing Gao, Xiao-Jun Bi, Jun Li and Peng-Fei Yin
The interaction between axion-like particles (ALPs) and photons induces ALP-photon oscillations in astrophysical magnetic fields, leading to spectral distortions in the γ-ray spectrum of blazars. The primary uncertainty of this phenomenon may originate from the magnetic field within the jet of the blazar. Many studies focus on a simple jet magnetic field model with a toroidal component exerting a predominant influence on regions far from the central region. While many investigations have explored the effects of ALP-photon oscillations using typical parameter values in this model, it is important to recognize that these parameters can be constrained by multi-wavelength observations. In this study, we utilize the high energy γ-ray spectrum of Mrk 421 obtained from MAGIC and Fermi-LAT observations. By employing multi-wavelength fitting with a one-zone synchrotron self-Compton model, we derive the parameters characterizing the simple toroidal balazar jet magnetic field model, and investigate their impacts on the ALP constraints.
{"title":"Impact of parameters in the toroidal blazar jet magnetic field model on axion-like particle constraints","authors":"Lin-Qing Gao, Xiao-Jun Bi, Jun Li and Peng-Fei Yin","doi":"10.1088/1475-7516/2025/01/031","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/031","url":null,"abstract":"The interaction between axion-like particles (ALPs) and photons induces ALP-photon oscillations in astrophysical magnetic fields, leading to spectral distortions in the γ-ray spectrum of blazars. The primary uncertainty of this phenomenon may originate from the magnetic field within the jet of the blazar. Many studies focus on a simple jet magnetic field model with a toroidal component exerting a predominant influence on regions far from the central region. While many investigations have explored the effects of ALP-photon oscillations using typical parameter values in this model, it is important to recognize that these parameters can be constrained by multi-wavelength observations. In this study, we utilize the high energy γ-ray spectrum of Mrk 421 obtained from MAGIC and Fermi-LAT observations. By employing multi-wavelength fitting with a one-zone synchrotron self-Compton model, we derive the parameters characterizing the simple toroidal balazar jet magnetic field model, and investigate their impacts on the ALP constraints.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"28 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936724","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 : 2025-01-09DOI: 10.1088/1475-7516/2025/01/032
Milko Estrada and Rodrigo Aros
We present a new family of regular black holes (RBH) in Pure Lovelock gravity, where the energy density is determined by the gravitational vacuum tension, which varies for each value of n in each Lovelock case. Speculatively, our model may capture quantum effects through gravitational tension. In this way, a hypothetical analogy is drawn between the pair production ratio in the Schwinger effect and our energy density. A notable feature of our model is that the regular solution closely resembles the vacuum solution before reaching the event horizon. For odd n, the transverse geometry is spherical, with phase transitions occurring during evaporation, and the final state of this process is a remnant. For even n, the transverse geometry is non trivial and corresponds to a hyperboloid. In the case of d = 2n+1 with even n, we find an RBH without a dS core and no inner horizon (whose presence has been recently debated in the literature due to the question of whether its presence is unstable or not), and no phase transitions. For d > 2n + 1 with even n, the RBH possesses both an event horizon and a cosmological horizon, also with no inner horizon present. The existence of the cosmological horizon arises without the usual requirement of a positive cosmological constant. From both numerical and analytical analysis, we deduce that as the event horizon expands and the cosmological horizon contracts, thermodynamic equilibrium is achieved in a remnant when the two horizons coincide.
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