Astroparticle Physics最新文献

{"title":"Axionic quantum fluctuations, dark energy, and the Hubble tension","authors":"L. Acedo","doi":"10.1016/j.astropartphys.2025.103111","DOIUrl":"10.1016/j.astropartphys.2025.103111","url":null,"abstract":"<div><div>The cosmological constant is now a fundamental ingredient of the standard ΛCDM model, and its value is constrained by concordance with empirical data. Despite its importance in modern cosmology, we still do not understand its origin. A naive calculation of the contribution of the quantum vacuum fluctuations to vacuum energy (considering it to be the source of the cosmological constant) yields predictions 120 orders of magnitude larger than observations. This poses one of the most celebrated unsolved problems in physics and cosmology. This work discusses a model of quantum-thermal fluctuations of the cosmic microwave background with a Planck factor. Fluctuations of a bosonic field are studied, and we show that they could match the vacuum energy density if they correspond to an axionic field with a particle rest mass in the range of a fraction of a meV. This mass range is in agreement with present bounds on the mass of the Peccei–Quinn axions arising from the spontaneous symmetry breaking that explains CP conservation in strong interactions, as well as estimations of the mass of axions in the galactic halo and experiments on Shapiro step anomalies using Josephson junctions. We also show that this model can clarify the Hubble tension debate, i.e., the statistically significant discrepancy between measurements of the Hubble parameter based upon the cosmic microwave background and those using low redshift observations.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"169 ","pages":"Article 103111"},"PeriodicalIF":4.2,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143767551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Beyond the local Universe: Impacts of scalar field coupled to non-relativistic neutrinos on bulk flow","authors":"Muhammad Yarahmadi","doi":"10.1016/j.astropartphys.2025.103110","DOIUrl":"10.1016/j.astropartphys.2025.103110","url":null,"abstract":"<div><div>This study explores the role of neutrinos in the Universe’s expansion history, tracing their transition from a relativistic phase in the early Universe to non-relativistic massive particles at later epochs. Within the framework of neutrino coupling with a scalar field, we examine cosmic evolution from radiation domination to dark energy dominance. By analyzing combined datasets (Pantheon+, Cosmic Microwave Background, Baryon Acoustic Oscillations, Cosmic Chronometers, and CMB lensing), we constrain the total neutrino mass to <span><math><mrow><mo>∑</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>ν</mi></mrow></msub><mo>&lt;</mo><mn>0</mn><mo>.</mo><mn>105</mn><mspace></mspace><mi>eV</mi></mrow></math></span> (95% CL). The transition redshifts <span><math><msub><mrow><mi>z</mi></mrow><mrow><mi>nr</mi></mrow></msub></math></span> range from 76 to 205, marking the onset of matter domination. The coupling parameter is constrained to <span><math><mrow><mi>α</mi><mo>=</mo><mn>5</mn><mo>.</mo><mn>64</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>1</mn></mrow></math></span>, consistent with growing neutrino quintessence, reinforcing the role of neutrinos despite their small mass. Late-time evolution analyses, comparing scenarios with and without neutrino coupling, reveal that non-relativistic neutrinos contribute to cosmic anisotropy. At low redshifts (<span><math><mrow><mn>0</mn><mo>.</mo><mn>001</mn><mo>&lt;</mo><mi>z</mi><mo>&lt;</mo><mn>0</mn><mo>.</mo><mn>1</mn></mrow></math></span>), the bulk flow direction aligns with the CMB dipole, while at higher redshifts, it correlates with the dark energy dipole. The evolution of neutrino density-to-redshift ratios suggests that a decreasing neutrino density weakens gravitational influence, leading to an increase in bulk velocity within <span><math><mrow><mn>0</mn><mo>.</mo><mn>1</mn><mo>&lt;</mo><mi>z</mi><mo>&lt;</mo><mn>1</mn></mrow></math></span> and a decline within <span><math><mrow><mn>1</mn><mo>&lt;</mo><mi>z</mi><mo>&lt;</mo><mn>1</mn><mo>.</mo><mn>4</mn></mrow></math></span>. These findings highlight the role of non-relativistic neutrinos in shaping cosmic anisotropy and dark energy dynamics, offering new perspectives on the Universe’s large-scale evolution.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"169 ","pages":"Article 103110"},"PeriodicalIF":4.2,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143767556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Characterization of a fiber laser hydrophone for acoustic neutrino detection","authors":"E.J. Buis ,&nbsp;A.M. von Benda-Beckmann ,&nbsp;E. Doppenberg ,&nbsp;J. Dorant ,&nbsp;T.H. Jansen ,&nbsp;P. Toet ,&nbsp;P. Verhooren ,&nbsp;J. de Vreugd","doi":"10.1016/j.astropartphys.2025.103109","DOIUrl":"10.1016/j.astropartphys.2025.103109","url":null,"abstract":"<div><div>This paper presents the development and characterization of a fiber laser hydrophone designed for deep-sea applications, with a focus on detecting neutrino interactions via their acoustic signatures. The hydrophone design includes a static pressure compensation mechanism, ensuring reliable operation at depths exceeding 1 km. The performance of the hydrophone was evaluated through laboratory tests and experiments in an anechoic basin, where its transfer function was measured before and after a 140-bar pressure cycle. The results show that the hydrophone maintains its sensitivity, with resonance peaks identified in both low- and high-frequency ranges. The hydrophone’s sensitivity to acoustic signals was also compared to ambient sea state noise levels, demonstrating compatibility with the lowest noise conditions.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"170 ","pages":"Article 103109"},"PeriodicalIF":4.2,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"I-C-Q relations for rapidly rotating stable hybrid stars","authors":"Sujan Kumar Roy,&nbsp;Gargi Chaudhuri","doi":"10.1016/j.astropartphys.2025.103108","DOIUrl":"10.1016/j.astropartphys.2025.103108","url":null,"abstract":"<div><div>A number of hadronic equations of state for neutron stars have been investigated for the purpose of the present paper, considering the fact that at sufficiently high density, heavy baryons and quark phases may appear. The observational limits from NICER, GW170817, etc., are obeyed by our choice of equations of state. The universal relations are investigated for both slowly and rapidly rotating neutron stars with heavy baryons present inside the core. For slowly rotating stars, the universality of the I-Love-Q relations is verified, and the I-C-Q relations are inferred to be universal for rapidly rotating stars. Further, we extend the investigation to obtain the universal relations for compact stars containing the quark core, where the connected stable branch of such hybrid stars is considered. The parameters of the I-Love-Q and I-C-Q universal relations are obtained for slowly rotating and rapidly rotating hybrid stars, respectively. These relations would enable extracting information, within the context of general relativity, from astrophysical systems involving rapidly rotating neutron stars.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"170 ","pages":"Article 103108"},"PeriodicalIF":4.2,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Measurement of cosmic muon-induced neutron background with ISMRAN detector in a non-reactor environment","authors":"R. Dey ,&nbsp;P.K. Netrakanti ,&nbsp;D.K. Mishra ,&nbsp;S.P. Behera ,&nbsp;R. Sehgal ,&nbsp;V. Jha ,&nbsp;L.M. Pant","doi":"10.1016/j.astropartphys.2025.103101","DOIUrl":"10.1016/j.astropartphys.2025.103101","url":null,"abstract":"<div><div>The Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) is an above-ground, very short baseline reactor anti-neutrino (<span><math><msub><mrow><mover><mrow><mi>ν</mi></mrow><mo>¯</mo></mover></mrow><mrow><mi>e</mi></mrow></msub></math></span>) experiment, located inside the Dhruva research reactor facility, Mumbai, India. The primary goal of the ISMRAN experiment is the indirect detection of reactor <span><math><msub><mrow><mover><mrow><mi>ν</mi></mrow><mo>¯</mo></mover></mrow><mrow><mi>e</mi></mrow></msub></math></span> through an inverse beta decay (IBD) process, using a cluster of 90 optically segmented plastic scintillator detectors, weighing <span><math><mo>∼</mo></math></span>1 ton. However, the most difficult to distinguish correlated background for the ISMRAN experiment is from fast neutrons, which cannot be actively rejected and as a consequence mimics the IBD process through proton recoil inside the detector’s volume. In this work, we present the neutron capture time response and energy deposition of neutron capture signals generated by cosmic muons in the ISMRAN geometry, and we compare these experimental results with Geant4-based Monte Carlo (MC) simulations. The obtained mean capture time of fast neutrons is 74.46 <span><math><mo>±</mo></math></span> 5.98 <span><math><mi>μ</mi></math></span>s and is comparable with the MC simulation results. The efficiency-corrected rate of muon-induced neutron background inside the ISMRAN geometry, due to the presence of a passive shielding structure of 10 cm lead followed by 10 cm borated polyethylene with a surface area of 600 cm², deployed on top of the ISMRAN setup, is reported to be 1334 ± 64 (stat.) <span><math><mo>±</mo></math></span> 70 (sys.) per day. This result shows good agreement with the expected background rate from MC simulations using Geant4. Additionally, we also estimate the muon-induced fast-neutron rate in the ISMRAN geometry for the actual shielding configuration of 9000 cm² surface area to be 3335 ± 160 (stat.) <span><math><mo>±</mo></math></span> 175 (sys.) neutrons day^-1 through an extrapolation, after incorporating the model dependent acceptance correction factor from the Geant4 MC simulation. Finally, using these results, we evaluate the neutron production yield due to the composite shielding in the ISMRAN geometry, which is 2.81<span><math><mo>×</mo></math></span> 10^-5 neutrons per <span><math><mi>μ</mi></math></span> per (g/cm²) at sea level. These results will be significant in the context of differentiating correlated background from true <span><math><msub><mrow><mover><mrow><mi>ν</mi></mrow><mo>¯</mo></mover></mrow><mrow><mi>e</mi></mrow></msub></math></span> events at the actual measurement site inside the reactor facility.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"169 ","pages":"Article 103101"},"PeriodicalIF":4.2,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Shadows and optical appearances of black holes in R2 gravity","authors":"Khadije Jafarzade ,&nbsp;Sanjar Shaymatov ,&nbsp;Mubasher Jamil","doi":"10.1016/j.astropartphys.2025.103100","DOIUrl":"10.1016/j.astropartphys.2025.103100","url":null,"abstract":"<div><div>In this paper, we consider a charged AdS/dS black hole (BH) in <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> gravity and study its optical features, including the shadow’s geometrical shape and the energy emission rate. Additionally, we look for criteria to restrict the free parameters of the theory by comparing them to observational data of M87<span><math><msup><mrow></mrow><mrow><mo>⋆</mo></mrow></msup></math></span>. Then, we employ the Newman-Janis algorithm to build the rotating counterpart of the static solution in <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> gravity and calculate the energy emission rate for the rotating case as well as discuss how the rotation factor and other parameters of this theory affect the emission of particles around the BHs. In the following, we consider the obtained rotating BH as a supermassive black hole and evaluate the parameters of the model with shadow size estimates based on the observations of M87<span><math><msup><mrow></mrow><mrow><mo>⋆</mo></mrow></msup></math></span> from EHT.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"168 ","pages":"Article 103100"},"PeriodicalIF":4.2,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143534890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"The time evolution of the low-energy deuteron fluxes measured in Cosmic Rays with the PAMELA experiment from the 23rd solar minimum to the 24th solar maximum","authors":"A. Lenni ,&nbsp;M. Boezio ,&nbsp;R. Munini ,&nbsp;W. Menn ,&nbsp;N. Marcelli ,&nbsp;M.D. Ngobeni ,&nbsp;D.C. Ndiitwani ,&nbsp;I.I. Ramokgaba ,&nbsp;M.S. Potgieter ,&nbsp;O. Adriani ,&nbsp;G.C. Barbarino ,&nbsp;G.A. Bazilevskaya ,&nbsp;R. Bellotti ,&nbsp;E.A. Bogomolov ,&nbsp;M. Bongi ,&nbsp;V. Bonvicini ,&nbsp;A. Bruno ,&nbsp;F. Cafagna ,&nbsp;D. Campana ,&nbsp;P. Carlson ,&nbsp;N. Zampa","doi":"10.1016/j.astropartphys.2025.103089","DOIUrl":"10.1016/j.astropartphys.2025.103089","url":null,"abstract":"<div><div>The space-borne PAMELA experiment was launched on the 15th of June 2006 on board the Russian satellite Resurs-DK1 from the Baikonur Cosmodrome. The PAMELA instrument performed high-precision measurements of cosmic rays over a wide energy range until January 2016.</div><div>We present the yearly average deuteron spectra for the 23rd solar minimum (July 2006 – January 2009) and the first part of the 24th solar maximum (until September 2014). The deuterons were selected with a rigidity between 0.75 and 2.6 GV by combining the Time of Flight (ToF) and the tracker systems. The measured spectra display a rising trend toward the solar minimum followed by a decreasing trend as the solar maximum approaches. The corresponding deuteron-to-proton flux ratios show time dependence at the lowest rigidities, as expected due to the different charge-to-mass ratios and the different shapes of the respective local interstellar spectra. These results are significant for the fine-tuning of propagation and modulation models of cosmic rays through the heliosphere.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"168 ","pages":"Article 103089"},"PeriodicalIF":4.2,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cosmological bounds on a possible electron-to-proton mass ratio variation and constraints in the lepton specific 2HDM","authors":"R.G. Albuquerque ,&nbsp;R.F.L. Holanda ,&nbsp;I.E.T. R. Mendonça ,&nbsp;P.S. Rodrigues da Silva","doi":"10.1016/j.astropartphys.2025.103090","DOIUrl":"10.1016/j.astropartphys.2025.103090","url":null,"abstract":"<div><div>In this work, we test a possible redshift variation of the electron-to-proton mass ratio, <span><math><mrow><mi>μ</mi><mo>=</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>e</mi></mrow></msub><mo>/</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>p</mi></mrow></msub></mrow></math></span>, directly from galaxy cluster gas mass fraction measurements and type Ia supernovae observations. Our result reveals no variation of <span><math><mi>μ</mi></math></span> within 1 <span><math><mi>σ</mi></math></span>. From the point of view of Particle Physics, we can use the precision on these results to constrain the parameter space of models beyond the Standard Model of electroweak interactions. We exemplify this by focusing on a specific Two-Higgs doublet model (2HDM), where the second scalar doublet couples exclusively to leptons. An important parameter in the model concerns the ratio between its vacuum expectation values, defined by <span><math><mrow><mo>tan</mo><mi>β</mi><mo>≡</mo><msub><mrow><mi>v</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>/</mo><msub><mrow><mi>v</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></math></span>. In our approach, we can constrain the inverse parameter <span><math><mrow><mo>(</mo><mo>cot</mo><mi>β</mi><mo>)</mo></mrow></math></span> to an optimal value, <span><math><mrow><mrow><mo>(</mo><mo>cot</mo><mi>β</mi><mo>)</mo></mrow><mo>=</mo><mrow><mo>(</mo><mn>2</mn><mo>.</mo><mn>003</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>081</mn><mo>)</mo></mrow><mi>⋅</mi><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></math></span>, with the highest vacuum expectation value for 2HDM, <span><math><msub><mrow><mi>v</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, estimated at around <span><math><mrow><mn>240</mn><mo>.</mo><mn>57</mn><mo>±</mo><mn>2</mn><mo>.</mo><mn>93</mn></mrow></math></span> GeV. Also, by taking into account the discrepancy in the anomalous magnetic moment of the muon found between theory and experiment, we can reduce the validity region for this model and establish bounds on the scalar masses, in light of our findings from galaxy cluster data for <span><math><mi>μ</mi></math></span>. This study contributes valuable insights to the understanding of the interface between Particle Physics and Astrophysics, establishing a new interrelationship between data on the large-scale structure of the Universe and subatomic Physics.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"168 ","pages":"Article 103090"},"PeriodicalIF":4.2,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Quantifying energy fluence and its uncertainty for radio emission from particle cascades in the presence of noise","authors":"Sara Martinelli ,&nbsp;Tim Huege ,&nbsp;Diego Ravignani ,&nbsp;Harm Schoorlemmer","doi":"10.1016/j.astropartphys.2025.103091","DOIUrl":"10.1016/j.astropartphys.2025.103091","url":null,"abstract":"<div><div>Measurements of radio signals induced by an astroparticle generating a cascade present a challenge because they are always superposed with an irreducible noise contribution. Quantifying these signals constitutes a non-trivial task, especially at low signal-to-noise ratios (SNR). Because of the randomness of the noise phase, the measurements can be either a constructive or a destructive superposition of signal and noise. To recover the electromagnetic energy of the cascade from the radio measurements, the energy fluence, i.e. the time integral of the Poynting vector, has to be estimated. Conventionally, noise subtraction in the time domain has been employed for energy fluence reconstruction, yielding significant biases at low signal-to-noise ratios. In several analyses, this bias is mitigated by imposing an SNR threshold cut, though this option is not ideal as it excludes valuable data. Additionally, the uncertainties derived from the conventional method are underestimated, even for large SNR values. To address this known issue, the uncertainties have so far typically been approximated and corrected by using ad-hoc terms. This work tackles these challenges by detailing a method to correctly estimate the uncertainties and lower the reconstruction bias in quantifying radio signals, thereby, ideally, eliminating the need for an SNR cut. The development of the method is based on a robust theoretical and statistical background, and the estimation of the fluence is performed in the frequency domain, allowing for the improvement of further analyses by providing access to frequency-dependent fluence estimation.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"168 ","pages":"Article 103091"},"PeriodicalIF":4.2,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"The influence of Sun’s and Moon’s shadows on cosmic-ray anisotropy","authors":"Xuan’ang Ye,&nbsp;Yi Zhang,&nbsp;Jiayin He,&nbsp;Shiping Zhao","doi":"10.1016/j.astropartphys.2025.103088","DOIUrl":"10.1016/j.astropartphys.2025.103088","url":null,"abstract":"<div><div>Large-scale anisotropy, with amplitudes reaching approximately 0.1% at TeV energies, has been observed by multiple cosmic-ray experiments. The obstruction of cosmic rays by the Sun and Moon creates shadow effects, potentially impacting the observed cosmic ray anisotropy. To evaluate these effects, this study calculates the contributions of the Sun’s and Moon’s shadows to the overall cosmic-ray anisotropy in both local solar and sidereal time. The analysis reveals that in local sidereal time, the total 1D projection amplitude of the anisotropy is around 0.003%, which is significantly smaller than the observed cosmic-ray anisotropy. This indicates that the influence of the Sun’s and Moon’s shadows on cosmic-ray anisotropy analysis in local sidereal time is negligible. In contrast, in local solar time, the shadow-induced deficit appears in a very small time bin, with a magnitude comparable to that of the cosmic-ray solar anisotropy. This deficit could serve as a benchmark for validating anisotropy measurements in future facilities.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"168 ","pages":"Article 103088"},"PeriodicalIF":4.2,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}