Journal of Cosmology and Astroparticle Physics最新文献_第2页

New realisation of light thermal dark matter with enhanced detection prospects 光热暗物质的新实现与增强的探测前景

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-17 DOI: 10.1088/1475-7516/2024/12/043

Amit Adhikary, Debasish Borah, Satyabrata Mahapatra, Indrajit Saha, Narendra Sahu and Vicky Singh Thounaojam

引用次数: 0

Testing No slip model with pulsar timing arrays: NANOGrav and IPTA

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-17 DOI: 10.1088/1475-7516/2024/12/045

Mohammadreza Davari, Alireza Allahyari and Shahram Khosravi

引用次数: 0

Exactly solvable stochastic spectator 完全可解的随机旁观者

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-17 DOI: 10.1088/1475-7516/2024/12/044

Masazumi Honda, Ryusuke Jinno and Koki Tokeshi

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Exploring non-radial oscillation modes in dark matter admixed neutron stars 探索暗物质掺杂中子星的非径向振荡模式

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-17 DOI: 10.1088/1475-7516/2024/12/042

Pratik Thakur, Anil Kumar, Vivek Baruah Thapa, Vishal Parmar and Monika Sinha

引用次数: 0

diffSph: a Python tool to compute diffuse signals from dwarf spheroidal galaxies diffSph：计算矮球状星系漫反射信号的 Python 工具

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-17 DOI: 10.1088/1475-7516/2024/12/046

Martin Vollmann, Finn Welzmüller and Lovorka Gajović

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Investigating rotating black holes in bumblebee gravity: insights from EHT observations 研究大黄蜂引力中的旋转黑洞：EHT 观测的启示

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-17 DOI: 10.1088/1475-7516/2024/12/047

Shafqat Ul Islam, Sushant G. Ghosh and Sunil D. Maharaj

{"title":"Investigating rotating black holes in bumblebee gravity: insights from EHT observations","authors":"Shafqat Ul Islam, Sushant G. Ghosh and Sunil D. Maharaj","doi":"10.1088/1475-7516/2024/12/047","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/12/047","url":null,"abstract":"The EHT observation revealed event horizon-scale images of the supermassive black holes Sgr A* and M87* and these results are consistent with the shadow of a Kerr black hole as predicted by general relativity. However, Kerr-like rotating black holes in modified gravity theories can not ruled out, as they provide a crucial testing ground for these theories through EHT observations. It motivates us to investigate the bumblebee theory, a vector-tensor extension of the Einstein-Maxwell theory that permits spontaneous symmetry breaking, resulting in the field acquiring a vacuum expectation value and introducing Lorentz violation. We present rotating black holes within this bumblebee gravity model, which includes an additional parameter ℓ alongside the mass M and spin parameter a — namely RBHBG. Unlike the Kerr black hole, an extremal RBHBG, for ℓ < 0, refers to a black hole with angular momentum a > M. We derive an analytical formula necessary for the shadow of our rotating black holes, then visualize them with varying parameters a and ℓ, and also estimate the black hole parameters using shadow observables viz. shadow radius Rs, distortion δs, shadow area A and oblateness D using two well-known techniques. We find that ℓ incrementally increases the shadow size and causes more significant deformation while decreasing the event horizon area. Remarkably, an increase in ℓ enlarges the shadow radius irrespective of spin or inclination angle θ0.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"4 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832197","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

Massive neutrinos and cosmic composition 大质量中微子和宇宙构成

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-17 DOI: 10.1088/1475-7516/2024/12/048

Marilena Loverde and Zachary J. Weiner

{"title":"Massive neutrinos and cosmic composition","authors":"Marilena Loverde and Zachary J. Weiner","doi":"10.1088/1475-7516/2024/12/048","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/12/048","url":null,"abstract":"Cosmological data probe massive neutrinos via their effects on the geometry of the Universe and the growth of structure, both of which are degenerate with the late-time expansion history. We clarify the nature of these degeneracies and the individual roles of both probes in neutrino mass inference. Geometry is strongly sensitive to neutrino masses: within ΛCDM, the primary cosmic microwave background anisotropies alone impose that the matter fraction Ωm must increase fivefold with increasing neutrino mass. Moreover, large-scale structure observables, like weak lensing of the CMB, are dimensionless and thus depend not on the matter density (as often quoted) but in fact the matter fraction. We explore the consequential impact of this distinction on the interplay between probes of structure, low-redshift distances, and CMB anisotropies. We derive constraints on the neutrino's masses independently from their suppression of structure and impact on geometry, showing that the latter is at least as important as the former. While the Dark Energy Spectroscopic Instrument's recent baryon acoustic oscillation data place stringent bounds largely deriving from their geometric incompatibility with massive neutrinos, all recent type Ia supernova datasets drive marginal preferences for nonzero neutrino masses because they prefer substantially larger matter fractions. Recent CMB lensing data, however, neither exclude neutrinos' suppression of structure nor constrain it strongly enough to discriminate between mass hierarchies. Current data thus evince not a need for modified dynamics of neutrino perturbations or structure growth but rather an inconsistent compatibility with massive neutrinos' impact on the expansion history. We identify two of DESI's measurements that strongly influence its constraints, and we also discuss neutrino mass measurements in models that alter the sound horizon.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"47 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832196","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

Gauge theory meets cosmology

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-13 DOI: 10.1088/1475-7516/2024/12/040

Massimo Bianchi, Giuseppe Dibitetto and Jose Francisco Morales

{"title":"Gauge theory meets cosmology","authors":"Massimo Bianchi, Giuseppe Dibitetto and Jose Francisco Morales","doi":"10.1088/1475-7516/2024/12/040","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/12/040","url":null,"abstract":"We reconsider linear perturbations around general Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmological backgrounds. Exploiting gauge freedom involving only time reparametrizations, we write down classical background solutions analytically, for an arbitrary number of fluid components. We then show that the time evolution of scalar and tensor adiabatic perturbations are governed by Schrödinger-like differential equations of generalized Heun type. After recovering known analytic results for a single-component fluid, we discuss more general situations with two and three different fluid components, with special attention to the combination of radiation, matter and vacuum energy, which is supposed to describe the ΛCDM model. The evolution of linear perturbations of a flat ΛCDM universe is described by a two-transient model, where the transitions from radiation to matter and matter to vacuum energy are governed by a Heun equation and a Hypergeometric equation, respectively. We discuss an analytic approach to the study of the general case, involving generalized Heun equations, that makes use of (quantum) Seiberg-Witten curves for 𝒩 = 2 supersymmetric gauge theories and has proven to be very effective in the analysis of Black-Hole, fuzzball and ECO perturbations.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"4 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815653","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

Exploring the discrepancy between Planck PR3 and ACT DR4

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-13 DOI: 10.1088/1475-7516/2024/12/038

Dhiraj Kumar Hazra, Benjamin Beringue, Josquin Errard, Arman Shafieloo and George F. Smoot

{"title":"Exploring the discrepancy between Planck PR3 and ACT DR4","authors":"Dhiraj Kumar Hazra, Benjamin Beringue, Josquin Errard, Arman Shafieloo and George F. Smoot","doi":"10.1088/1475-7516/2024/12/038","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/12/038","url":null,"abstract":"We explore the scales and the extent of disagreement between Planck PR3 and Atacama Cosmology Telescope (ACT) DR4 data. Planck and ACT data have substantial overlap in the temperature anisotropy data between scales corresponding to multipoles ℓ ≃ 600–2500 with complementing coverage of larger angular scales by Planck and smaller angular scales by ACT. Since the same cosmology should govern the anisotropy spectrum at all scales, we probe this disagreement in the primordial power spectrum. We use a parametric form of power law primordial spectrum that allows changes in the spectral tilt. We also reconstruct the primordial spectrum with a non-parametric method from both Planck and ACT temperature data. We find the disagreement exists within scales 0.08–0.16 Mpc-1 where ACT temperature data prefers a scale invariant/blue spectrum. At scales larger and smaller than this window, ACT data strongly prefers a red tilt, which is consistent with Planck. This change in the spectral tilt can be identified in the ACT data at 2σ C.L. without using Planck data, indicating that the tension is driven by different preferences for tilts within the ACT data. The addition of Planck data up to intermediate scales (ℓ ≤ 650) increases this significance to 3σ. Given the large overlap between Planck and ACT within 0.08–0.16 Mpc-1 and considering the internal consistency between different Planck temperature and polarization spectra, the scope of new physics as a solution to the tension remains limited. Our results — a strong preference for an intermediate transition in spectral tilt and the variation of this preference in different data combinations — indicate that systematic effects can be misperceived as new physics emerging from different non-standard cosmological processes.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"31 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815736","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

Gravitational waves from primordial black hole isocurvature: the effect of non-Gaussianities

IF 6.4 2区物理与天体物理

Journal of Cosmology and Astroparticle Physics Pub Date : 2024-12-13 DOI: 10.1088/1475-7516/2024/12/039

Xin-Chen He, Yi-Fu Cai, Xiao-Han Ma, Theodoros Papanikolaou, Emmanuel N. Saridakis and Misao Sasaki

{"title":"Gravitational waves from primordial black hole isocurvature: the effect of non-Gaussianities","authors":"Xin-Chen He, Yi-Fu Cai, Xiao-Han Ma, Theodoros Papanikolaou, Emmanuel N. Saridakis and Misao Sasaki","doi":"10.1088/1475-7516/2024/12/039","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/12/039","url":null,"abstract":"Ultra-light primordial black holes (PBHs) with masses MPBH < 5 × 108g can dominate transiently the energy budget of the Universe and reheat the Universe through their evaporation taking place before Big Bang Nucleosynthesis. The isocurvature energy density fluctuations associated to the inhomogeneous distribution of a population of such PBHs can induce an abundant production of GWs due to second-order gravitational effects. In this work, we discuss the effect of primordial non-Gaussianity on the clustering properties of PBHs and study the effect of a clustered PBH population on the spectral shape of the aforementioned induced GW signal. In particular, focusing on local-type non-Gaussianity we find a double-peaked GW signal with the amplitude of the low-frequency peak being proportional to the square of the non-Gaussian parameterτNL. Remarkably, depending on the PBH mass MPBH and the initial abundance of PBHs at formation time, i.e. ΩPNH,f, this double-peaked GW signal can lie well within the frequency bands of forthcoming GW detectors, namely LISA, ET, SKA and BBO, hence rendering this signal falsifiable by GW experiments and promoting it as a novel portal probing the primordial non-Gaussianity.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"16 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815734","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