Journal of Cosmology and Astroparticle Physics最新文献_第5页

Quantitative classicality in cosmological interactions during inflation 暴胀期间宇宙相互作用的定量经典性

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-22 DOI: 10.1088/1475-7516/2025/05/071

Yoann L. Launay, Gerasimos I. Rigopoulos and E.Paul S. Shellard

{"title":"Quantitative classicality in cosmological interactions during inflation","authors":"Yoann L. Launay, Gerasimos I. Rigopoulos and E.Paul S. Shellard","doi":"10.1088/1475-7516/2025/05/071","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/05/071","url":null,"abstract":"We examine the classical and quantum evolution of inflationary cosmological perturbations from quantum initial conditions, using the on-shell and off-shell contributions to correlators to investigate the signatures of interactions. In particular, we calculate the Keldysh contributions to the leading order bispectrum from past infinity, showing that the squeezed limit is dominated by the on-shell evolution. By truncating the time integrals in the analytic expressions for contributions to the bispectrum, we define a `quantum interactivity' and quantitatively identify scales and times for which it is sufficient to only assume classical evolution, given a fixed precision. In contrast to typical perceptions inspired by free two-point functions, we show that common non-linear contributions to inflationary perturbations can be well-described by classical evolution even prior to horizon crossing. The insights gained here can pave the way for quantitative criteria for justifying the validity of numerically simulating the generation and evolution of quantum fluctuations in inflation. In particular, we comment on the validity of using stochastic inflation to reproduce known in-in perturbative results. An extensive appendix provides a review of the Keldysh formulation of the in-in formalism with the initial state set at a finite, as opposed to infinite past, emphasizing the importance of considering temporal boundary terms and the initial state for correctly obtaining the propagators. We also show how stochastic dynamics can emerge as a sufficiently accurate approximation to the full quantum evolution. This becomes particularly transparent in the Keldysh description.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"97 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144130148","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}

引用次数: 0

Lattice simulations of axion-U(1) inflation: gravitational waves, magnetic fields, and scalar statistics 轴- u(1)膨胀的晶格模拟：引力波、磁场和标量统计

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-22 DOI: 10.1088/1475-7516/2025/05/079

Ramkishor Sharma, Axel Brandenburg, Kandaswamy Subramanian and Alexander Vikman

{"title":"Lattice simulations of axion-U(1) inflation: gravitational waves, magnetic fields, and scalar statistics","authors":"Ramkishor Sharma, Axel Brandenburg, Kandaswamy Subramanian and Alexander Vikman","doi":"10.1088/1475-7516/2025/05/079","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/05/079","url":null,"abstract":"We numerically study axion-U(1) inflation, focusing on the regime where the coupling between axions and gauge fields results in significant backreaction from the amplified gauge fields during inflation. These amplified gauge fields not only generate high-frequency gravitational waves (GWs), but also enhance spatial inhomogeneities in the axion field. GWs serve as key probe for constraining the coupling strength between the axion and gauge fields. We find that, when backreaction is important during inflation, the constraints on the coupling strength due to GW overproduction are relaxed compared to previous studies, in which backreaction matters only after inflation. Moreover, our results suggest that the probability density function (PDF) of axion fluctuations tends toward a Gaussian distribution even in cases where gauge field backreaction is important only after inflation. This aligns with previous studies where the same effect was observed for cases with strong backreaction during inflation. This finding can be crucial for future studies of primordial black hole (PBH) formation, which can further constrain the coupling strength. We also calculate the spectrum of the produced magnetic fields in this model and find that their strength is compatible with the observed lower limits.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"154 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144130198","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}

引用次数: 0

Nonlocal gravity in a proper tetrad frame: traversable wormholes 适当四分体框架中的非局部引力：可穿越虫洞

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-22 DOI: 10.1088/1475-7516/2025/05/069

Rocco D'Agostino and Vittorio De Falco

{"title":"Nonlocal gravity in a proper tetrad frame: traversable wormholes","authors":"Rocco D'Agostino and Vittorio De Falco","doi":"10.1088/1475-7516/2025/05/069","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/05/069","url":null,"abstract":"We investigate the revised Deser-Woodard model of nonlocal gravity involving four auxiliary scalar fields, introduced to explain the standard cosmological background expansion history without fine-tuning issues. In particular, we simplify the complex field equations within a proper tetrad frame, thereby recasting the original system into a more tractable equivalent differential problem. We show that, by initially postulating the form of the gtt metric component, it is possible to reconstruct the distortion function of the gravitational model. We then describe a step-by-step procedure for solving the vacuum field equations in the case of a static and spherically symmetric spacetime. We apply our technique to find new traversable wormholes supported purely by gravity by employing either analytical, perturbative, or numerical methods. Furthermore, we demonstrate that the role of the nonlocal effects is analogous to that of exotic matter in general relativity, owing to their quantum nature. Finally, we discuss the main geometric properties of the obtained solutions. Our results present a feasible avenue for identifying novel compact objects while enhancing the comprehension of nonlocal gravitational theories.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"22 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144130145","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}

引用次数: 0

Thin and thick bubble walls. Part III. Wall energy 薄而厚的气泡壁。第三部分。墙的能量

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-22 DOI: 10.1088/1475-7516/2025/05/076

Ariel Mégevand and Federico Agustín Membiela

引用次数: 0

Accretion in very early Universe and charge asymmetry 宇宙早期的吸积和电荷不对称

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-22 DOI: 10.1088/1475-7516/2025/05/068

N.A. Pozdnyakov

引用次数: 0

A bright future? Prospects for cosmological tests of GR with multimessenger gravitational wave events 光明的未来？多信使引力波事件对GR宇宙学检验的展望

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-22 DOI: 10.1088/1475-7516/2025/05/078

Elena Colangeli, Konstantin Leyde and Tessa Baker

{"title":"A bright future? Prospects for cosmological tests of GR with multimessenger gravitational wave events","authors":"Elena Colangeli, Konstantin Leyde and Tessa Baker","doi":"10.1088/1475-7516/2025/05/078","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/05/078","url":null,"abstract":"Further bright sirens — gravitational wave events with electromagnetic counterparts — are keenly awaited, but proving elusive. The exceptional event GW170817 had a profound impact on the landscape of viable cosmological extensions of General Relativity (GR); can we expect this kind of shift to be repeated in the next decade? In this work we will assess the potential constraints from bright sirens in the LIGO-Virgo-KAGRA O5 era and third generation detector era. We set up the statistical formalism for our constraints, and generate and analyse simulated data in the context of general scalar-tensor theories. We highlight the important role that gamma-ray burst detection has in breaking key parameter degeneracies. We find that the next ten bright sirens alone will not competitively constrain cosmological gravity, but that one year of third generation observations could confidently detect mild departures from GR, e.g. the Horndeski parameter αM ≠ 0 is detected at greater than 3σ. This justifies investment in a broad range of methods for gravitational wave cosmology (dark sirens, bright sirens and cross-correlation with large-scale structure) to ensure tests of cosmological gravity advance in both the short-term and the long-term.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"238 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144130197","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}

引用次数: 0

Effect of thermal conduction on accretion shocks in relativistic magnetized flows around rotating black holes 热传导对旋转黑洞周围相对论磁化流吸积激波的影响

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-21 DOI: 10.1088/1475-7516/2025/05/055

Monu Singh, Camelia Jana and Santabrata Das

{"title":"Effect of thermal conduction on accretion shocks in relativistic magnetized flows around rotating black holes","authors":"Monu Singh, Camelia Jana and Santabrata Das","doi":"10.1088/1475-7516/2025/05/055","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/05/055","url":null,"abstract":"We examine the effects of thermal conduction on relativistic, magnetized, viscous, advective accretion flows around rotating black holes considering bremsstrahlung and synchrotron cooling processes. Assuming the toroidal component of magnetic fields as the dominant one, we self-consistently solve the steady-state fluid equations to derive the global transonic accretion solutions for a black hole of spin ak. Depending on the model parameters, the magnetized accretion flow undergoes shock transitions and shock-induced global accretion solutions persist over a wide range of model parameters including the conduction parameter (Υs), plasma-β, and viscosity parameter (αB). We find that the shock properties — such as shock radius (rs), compression ratio (R), and shock strength (S) — are regulated by Υs, plasma-β, and αB. Furthermore, we compute the critical conduction parameter (Υscri), a threshold beyond which shock formation ceases to exist, and investigate its dependence on plasma-β and αB for both weakly rotating (ak → 0) and rapidly rotating (ak → 1) black holes. Finally, we examine the spectral energy distribution (SED) of the accretion disc and observe that increased thermal conduction and magnetic field strength lead to more luminous emission spectra from black hole sources.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"15 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144113985","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}

引用次数: 0

Cosmology and astrophysics of CP-violating axions 违反cp轴子的宇宙学和天体物理学

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-21 DOI: 10.1088/1475-7516/2025/05/056

Omar F. Ramadan, Jeremy Sakstein and Djuna Croon

引用次数: 0

Nonminimal superheavy dark matter 非极小超重暗物质

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-21 DOI: 10.1088/1475-7516/2025/05/060

Sarunas Verner

引用次数: 0

DeepWiener: neural networks for CMB polarization maps and power spectrum computation DeepWiener：用于微波背景极化图和功率谱计算的神经网络

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-05-21 DOI: 10.1088/1475-7516/2025/05/058

Belén Costanza, Claudia G. Scóccola and Matías Zaldarriaga

{"title":"DeepWiener: neural networks for CMB polarization maps and power spectrum computation","authors":"Belén Costanza, Claudia G. Scóccola and Matías Zaldarriaga","doi":"10.1088/1475-7516/2025/05/058","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/05/058","url":null,"abstract":"To study the early Universe, it is essential to estimate cosmological parameters with high accuracy, which depends on the optimal reconstruction of Cosmic Microwave Background (CMB) maps and the measurement of their power spectrum. In this paper, we generalize the neural network developed for applying the Wiener Filter, initially presented for temperature maps in previous work, to polarization maps. Our neural network has a UNet architecture, including an extra channel for the noise variance map, to account for inhomogeneous noise, and a channel for the mask. In addition, we propose an iterative approach for reconstructing the E and B-mode fields, while addressing the E-to-B leakage present in the maps due to incomplete sky coverage. The accuracy achieved is satisfactory compared to the Wiener Filter solution computed with the standard Conjugate Gradient method, and it is highly efficient, enabling the computation of the power spectrum of an unknown signal using the optimal quadratic estimator. We further evaluate the quality of the reconstructed maps at the power spectrum level along with their corresponding errors, finding that these errors are smaller than those obtained using the well-known pseudo-Cℓ approach. Our results show that increasing complexity in the applied mask presents a more significant challenge for B-mode reconstruction.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"32 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114051","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}

引用次数: 0