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Radiolarians are significant contributors to the oceanic primary productivity and the global silica cycle in the last 500 Myr. Their diversity throughout the Phanerozoic shows periodic fluctuations. We identify a possible abiotic candidate…

Populations and Evolution · Quantitative Biology 2024-02-15 Péter Ozsvárt , Emma Kun

The cause of the glacial cycles remains a mystery. The origin is widely accepted to be astronomical since paleoclimatic archives contain strong spectral components that match the frequencies of Earth's orbital modulation. Milankovitch…

Atmospheric and Oceanic Physics · Physics 2007-05-23 J. Kirkby , A. Mangini , R. A. Muller

We study solar modulation of galactic cosmic rays (GCRs) during the deep solar minimum, including the declining phase, of solar cycle 23 and compare the results of this unusual period with the results obtained during similar phases of the…

Solar and Stellar Astrophysics · Physics 2013-12-03 O. P. M. Aslam , Badruddin

In this paper, we study the galactic cosmic ray (GCR) variations over the solar cycles 23 and 24, with measurements from the NASA's ACE/CRIS instrument and the ground-based neutron monitors (NMs). The results show that the maximum GCR…

Solar and Stellar Astrophysics · Physics 2021-06-23 Shuai Fu , Xiaoping Zhang , Lingling Zhao , Yong Li

Galactic cosmic rays (GCRs), the highly energetic particles that may raise critical health issues for astronauts in space, are modulated by solar activity with their intensity lagging behind the sunspot number (SSN) variation by about one…

Solar and Stellar Astrophysics · Physics 2022-04-07 Yuming Wang , Jingnan Guo , Gang Li , Elias Roussos , Junwei Zhao

Galactic Cosmic Rays (GCRs) have to travel through the heliosphere before they interact with the Earth's atmosphere. During this, they are deflected by the Sun's magnetic field, causing variations in this field to imprint on the flux,…

The solar luminosity in the visible changes at the 10-3 level, following an 11 years period. In X-rays, which should not be there, the amplitude varies 100000 times stronger, making their mysterious origin since the discovery in 1938 even…

Solar and Stellar Astrophysics · Physics 2015-06-17 K. Zioutas , M. Tsagri , Y. K. Semertzidis , T. Papaevangelou , D. H. H. Hoffmann , V. Anastassopoulos

Galaxies with high star-formation rate surface densities often host large-scale outflows that redistribute energy, momentum, and baryons between the interstellar medium and the halo, making them a key feedback channel regulating galaxy…

Astrophysics of Galaxies · Physics 2025-09-23 Ellis R. Owen , Leonard E. C. Romano , Kentaro Nagamine

During the recent solar minimum between cycles 23 and 24 (solar minimum $P_{23/24}$) the intensity of Galactic Cosmic Rays (GCRs) measured at the Earth was the highest ever recorded since space age. It is the purpose of this paper to…

Solar and Stellar Astrophysics · Physics 2014-12-04 L. -L. Zhao , G. Qin , M. Zhang , B. Heber

We have studied the 27-day variations and their harmonics of the galactic cosmic ray (GCR) intensity, solar wind velocity, and interplanetary magnetic field (IMF) components in the recent prolonged solar minimum 23 24. The time evolution of…

Solar and Stellar Astrophysics · Physics 2015-04-02 R. Modzelewska , M. V. Alania

We argue that the diffusion of cosmic rays in the Galactic magnetic field has to be strongly anisotropic. As a result, the number of CR sources contributing to the local CR flux is reduced by a factor $\sim 200$. The CR density is therefore…

High Energy Astrophysical Phenomena · Physics 2019-05-22 M. Kachelriess

Galactic cosmic rays (GCRs) are affected by solar modulation while they propagate through the heliosphere. The study of the time variation of GCR spectra observed at Earth can shed light on the underlying physical processes, specifically…

Space Physics · Physics 2023-09-18 Claudio Corti , Peter Sadowski , Nikolay Nikonov , Marius Potgieter , Veronica Bindi

The anisotropy of cosmic rays (CRs) in the solar vicinity is generally at- tributed to the CR streaming due to the discrete distribution of CR sources or local magnetic field modulation. Recently, the two dimensional large scale CR…

Astrophysics of Galaxies · Physics 2012-04-17 Xiao-bo Qu , Yi Zhang , Liang Xue , Cheng Liu , Hong-bo Hu

Cosmic rays (CRs) leave their sources mainly along the local magnetic field; in doing so they excite both resonant and nonresonant modes through streaming instabilities. The excitation of these modes leads to enhanced scattering and in turn…

High Energy Astrophysical Phenomena · Physics 2021-06-10 Benedikt Schroer , Oreste Pezzi , Damiano Caprioli , Colby Haggerty , Pasquale Blasi

We constrain the energy at which the transition from Galactic to extragalactic cosmic rays occurs by computing the anisotropy at Earth of cosmic rays emitted by Galactic sources. Since the diffusion approximation starts to loose its…

High Energy Astrophysical Phenomena · Physics 2012-07-17 G. Giacinti , M. Kachelriess , D. V. Semikoz , G. Sigl

We present the temporal changes of the diffusion coefficient K of galactic cosmic rays (GCRs) at the Earth orbit calculated based on the experimental data using two different methods. The first approach is based on the Parker…

Space Physics · Physics 2015-02-04 Renata Modzelewska

Cosmic rays (CRs) are dynamically important for the formation and evolution of galaxies by regulating star formation and by powering galactic outflows. However, to what extent CRs regulate galaxy formation depends on the coupling strength…

Astrophysics of Galaxies · Physics 2023-12-27 Philipp Girichidis , Maria Werhahn , Christoph Pfrommer , Rüdiger Pakmor , Volker Springel

We investigate the possibility that the cosmic ray (CR) knee is entirely explained by the energy-dependent CR leakage from the Milky Way. We test this hypothesis calculating the trajectories of individual CRs with energies between…

High Energy Astrophysical Phenomena · Physics 2014-08-22 G. Giacinti , M. Kachelriess , D. V. Semikoz

We calculate the diffusion coefficients of charged cosmic rays (CR) propagating in regular and turbulent magnetic fields. If the magnetic field is dominated by an isotropic turbulent component, we find that CRs reside too long in the…

High Energy Astrophysical Phenomena · Physics 2018-07-24 G. Giacinti , M. Kachelriess , D. V. Semikoz

We argue that the degree of understanding the causes and mechanisms of the long-term variations (11-year and 22-year) in the galactic cosmic rays (GCR) characteristics is still insufficient and to improve it we need new approaches and…

Solar and Stellar Astrophysics · Physics 2015-09-03 M. Krainev , J. Kóta , M. S. Potgieter