Astrophysics最新文献_第3页

Observational Constraining of Viscous Ghost Dark Energy in f(R,T) Gravity f（R，T）引力中粘性幽灵暗能量的观测约束

IF 0.7 4区物理与天体物理

Astrophysics Pub Date : 2025-10-31 DOI: 10.1007/s10511-025-09889-8

Pinki, K. Devi, A. Kumar, P. Kumar

{"title":"Observational Constraining of Viscous Ghost Dark Energy in f(R,T) Gravity","authors":"Pinki, K. Devi, A. Kumar, P. Kumar","doi":"10.1007/s10511-025-09889-8","DOIUrl":"10.1007/s10511-025-09889-8","url":null,"abstract":"In the context of f (R, T) theory, we address the viscous ghost dark energy model for a homogeneous and isotropic flat universe. To talk about the universe′s evolution, we derive the Hubble, deceleration, and effective equation of state parameters. We analyze the computed cosmological parameters in light of the model parameters′ best fit values and limit the model parameters using the most recent cosmological observations. The deceleration parameter shows a smooth phase transition of the universe from decelerated to accelerated expansion. The universe remains in accelerating phase in future also which shows that dark energy will dominate the universe in future as well. We observe that effective equation of state in our model never cross the phantom divide line and approaches to ΛCDM model in the future. We observe current values of the Hubble parameter ({H}_{0}={66.567}_{-1.048}^{+1.151}) and ({H}_{0}={69.582}_{-0.813}^{+0.905}) for SNIa+OHD+SLS and SNIa+OHD+SH0ES, respectively. The estimated current ages of the universe are 15. 13 Gyr for SNIa+OHD+SLS and 15. 61 Gyr for the SNIa+OHD+SH0ES. We observe that the present model is able to resolve H0 tension and age problem of the standard ΛCDM model. Further, we apply higher order geometric analysis namely statefinder jerk, snap, and lerk parameters to discriminate our model with existing DE models. The trajectories in r - s and r - q planes pass through ΛCDM model during the evolution but the overall evolution of the trajectories differs from any known dark energy model.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 3","pages":"465 - 489"},"PeriodicalIF":0.7,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145555594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

A Novel Parametrized Dark Energy Model in a Flat Universe 平坦宇宙中一种新的参数化暗能量模型

IF 0.7 4区物理与天体物理

Astrophysics Pub Date : 2025-10-31 DOI: 10.1007/s10511-025-09890-1

C. Sivakumar

{"title":"A Novel Parametrized Dark Energy Model in a Flat Universe","authors":"C. Sivakumar","doi":"10.1007/s10511-025-09890-1","DOIUrl":"10.1007/s10511-025-09890-1","url":null,"abstract":"A novel dark energy model with an equation of state (EoS) given by: ω(z) = ω0 + ω1 z/(1 + ln(1 + z)) is proposed, which effectively captures the transition from deceleration to acceleration in the cosmic expansion. This model is motivated by recent observational measurements, all of which indicate a significant shift in the dynamics of the universe at intermediate redshifts (z ≈ 0.5). By utilizing a logarithmic damping term, the model allows for a smooth, redshift-dependent transition between matter, dark energy, and radiation domination, and avoids the abrupt transitions often observed in simpler models. In particular, the parameters ω0 and ω1 govern the early and late-time evolution of the equation of state. ω0 characterizes the late-time asymptotic behaviour, while ω1 controls the rate of transition at intermediate redshifts. The model is further examined from multiple theoretical standpoints: we establish its correspondence with viscous and logotropic dark fluids, reconstruct its scalar field theoretical counterpart (quintessence-type), and derive the effective equation of state ωeff (z), which confirms a smooth transition to an accelerating phase near z ~ 0.5. Furthermore, we perform a thermodynamic analysis to verify the validity of the generalized second law of thermodynamics (GSL) and ensure the model′s stability. The speed of sound, which is essential for stability analysis, is computed and analysed to ensure it remains positive and stable across all redshifts, ensuring that the model adheres to physical constraints. We analysed the present model with updated observational Hubble parameter data from cosmic chronometers, performing a full chi-square minimization and model selection analysis using the Akaike Information Criterion (AIC). The resulting best-fit parameters indicate a close match with data, yielding a ({chi }_{min}^{2}) comparable to ΛCDM and CPL, and a ∆AIC that confirms the present model as a competitive phenomenological alternative within the current cosmological framework.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 3","pages":"496 - 535"},"PeriodicalIF":0.7,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145555590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Viscous Chaplygin Gas in f(G) Theory of Gravity f(G)重力理论中的粘性Chaplygin气体

IF 0.7 4区物理与天体物理

Astrophysics Pub Date : 2025-10-31 DOI: 10.1007/s10511-025-09888-9

S. P. Hatkar, P. A. Agre, D. P. Tadas, S. D. Katore, D. D. Pawar

引用次数: 0

On Galactic Distribution of Different Pulsars 不同脉冲星在银河系的分布

IF 0.7 4区物理与天体物理

Astrophysics Pub Date : 2025-10-31 DOI: 10.1007/s10511-025-09883-0

R. R. Andreasyan, A. R. Andreasyan, G. M. Paronyan, A. G. Sukiasyan

引用次数: 0

Review of Recent Findings on Chemical Composition of Red Giants with Magnetic Fields 具有磁场的红巨星化学成分研究进展综述

IF 0.7 4区物理与天体物理

Astrophysics Pub Date : 2025-10-31 DOI: 10.1007/s10511-025-09880-3

L. S. Lyubimkov

{"title":"Review of Recent Findings on Chemical Composition of Red Giants with Magnetic Fields","authors":"L. S. Lyubimkov","doi":"10.1007/s10511-025-09880-3","DOIUrl":"10.1007/s10511-025-09880-3","url":null,"abstract":"Based on a series of studies recently carried out at the Crimean Astrophysical Observatory, we have analyzed the chemical composition of 20 G- and K-type giants with magnetic fields, comparing them with the chemical composition of 7 non-magnetic giants. Significant differences have been found in the lithium abundance and in the [N/C] ratio between magnetic and non-magnetic giants; both of these parameters are known to be sensitive indicators of stellar evolution. Lithium is shown to be absent in almost all non-magnetic giants, in full agreement with theoretical predictions concerning the evolution of giants that have undergone deep convective mixing during the first dredge-up. In contrast, most magnetic giants retain detectable lithium in their atmospheres. Furthermore, the [N/C] ratio, examined as a function of stellar age and mass, displays systematic differences between magnetic and non-magnetic giants. Possible explanations for the observed differences in the chemical composition of these two types of giants are discussed. It is also shown that the total C+N+O abundance, which apparently remains constant throughout the evolution, exhibits a clear dependence on [Fe/H] not only for the giants analyzed here, but also across a wider range of metallicity from –2.5 to +0.3.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 3","pages":"339 - 353"},"PeriodicalIF":0.7,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145555569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Temperature Effects in the Proto Neutron Star Phase of PSR J0740+6620 PSR J0740+6620原中子星相的温度效应

IF 0.7 4区物理与天体物理

Astrophysics Pub Date : 2025-10-31 DOI: 10.1007/s10511-025-09885-y

Xian-Feng Zhao, Wen-Bo Ding, Bin Tang

{"title":"Temperature Effects in the Proto Neutron Star Phase of PSR J0740+6620","authors":"Xian-Feng Zhao, Wen-Bo Ding, Bin Tang","doi":"10.1007/s10511-025-09885-y","DOIUrl":"10.1007/s10511-025-09885-y","url":null,"abstract":"Temperature effect in proto neutron star (PNS) PSR J0740+6620 is studied by using relativistic mean field theory and considering baryon octet. The nucleon coupling constant is chosen as GM1, and the temperature of the PNS is set as T = 7, 14, 21, 28, 35 MeV, respectively. Our results show that under the constraint of mass M = 2. 08 M⨀ of the PNS PSR J0740+6620, the radius R increases with increasing temperature T. With respect to the same baryon density ρ, the field strength of mesons σ, ω, ρ and the chemical potential of neutrons μn decrease while the field strength of σ* and ϕ increase with the increase of temperature T. The chemical potential of electron μe increases when the baryon density is less than ρ = 0.3 fm-3, but decreases when the baryon density is greater than ρ = 0.3 fm-3, companying with the increase of temperature T. Relative to the same baryon density ρ, the relative density of neutrons decreases while those of proton, Λ, Σ+, Σ0, Σ–, Ξ0, and Ξ– all increases with increasing temperature T. The central relative densities of neutrons decrease, while those of protons, hyperons Σ+, Σ0, Σ–, Ξ0, and Ξ– all increase with increasing temperature T. As for the relative density of hyperon Λ, it increases firstly, reaching a maximum value when the temperature is about T = 20 MeV, and then decreases with the increase of temperature T.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 3","pages":"403 - 417"},"PeriodicalIF":0.7,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145555571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Rate Coefficients for Collisional Transitions Between a Large Number of Rotational Levels of Disilicon Carbide (SiCSi) Colliding with Para-H2 (j = 0) 大量旋转能级碳化硅（SiCSi）与Para-H2 （j = 0）碰撞跃迁的速率系数

IF 0.7 4区物理与天体物理

Astrophysics Pub Date : 2025-10-31 DOI: 10.1007/s10511-025-09891-0

S. Chandra

{"title":"Rate Coefficients for Collisional Transitions Between a Large Number of Rotational Levels of Disilicon Carbide (SiCSi) Colliding with Para-H2 (j = 0)","authors":"S. Chandra","doi":"10.1007/s10511-025-09891-0","DOIUrl":"10.1007/s10511-025-09891-0","url":null,"abstract":"The SiCSi is considered as one of the important molecules responsible for the production of dust around the carbon-rich stars. First detection of the SiCSi has been in the envelope of red supergiant star IRC+10216. Cabrera-Gonzalez et al. (2023) have calculated collisional rate coefficients for the disilicon carbide (SiCSi) colliding with para-H2 (j = 0), in the CC (Close-Coupling) approximation, between 31 rotational levels, having energy up to 23. 844 cm-1. Though the calculations are performed for the kinetic temperature of 50 K, but they are found useful for the calculations with the temperature up to 30 K. For more reliable analysis of the molecule and for large kinetic temperature in an object, the data for large number of levels are essentially required. Thus, one needs to extend the calculations for a large number of rotational levels. In the present investigation, the work of Cabrera-Gonzalez et al. (2023) has been extended for 78 rotational levels, having energy up to 61. 746 cm-1. The present calculations however have been performed in the CS (Coupled-States) approximation.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 3","pages":"490 - 495"},"PeriodicalIF":0.7,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145555596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Search for Dwarf Galaxies in the Southwestern Sector of the Local Cosmic Void 在本地宇宙空洞的西南区域寻找矮星系

IF 0.7 4区物理与天体物理

Astrophysics Pub Date : 2025-10-31 DOI: 10.1007/s10511-025-09879-w

A. A. Popova, I. D. Karachentsev

引用次数: 0

Correction to: Electromagnetic Radiation from a Relativistic Jet Induced by a Plane Gravitational Wave 修正：由平面引力波引起的相对论性射流的电磁辐射

IF 0.7 4区物理与天体物理

Astrophysics Pub Date : 2025-09-13 DOI: 10.1007/s10511-025-09877-y

V. Epp, K. Osetrin, E. Osetrina

引用次数: 0

Correction to: Induced Electromagnetic Radiation from a Charged Cloud in a Plane Gravitational Wave 修正：平面引力波中带电云的感应电磁辐射