On the fractal properties of cosmic rays and Sun dynamics cross-correlations

We investigate the cosmic rays and ten physical parameters of heliosphere behavior considering the scaling features of their temporal evolution. Our analysis start with the cosmic rays measurements by a neutron monitor station located in Moscow, as well sunspot, Ap index, Na/Np, Alfven mach number, DST index, Kp index, Plasma beta (β ), Proton temperature, F10.7 index and Field magnitude |B| (Interplanetary Magnetic Field, IMF), for the period 1976 to early 2020. Each of these datasets was analyzed by using the Multifractal Detrended Fluctuation Analysis and Multifractal Detrended Cross-Correlation Analysis in order to investigate intrinsic properties, like self-similarity and the spectrum of singularities. The main result obtained is that the cosmic rays time series as well the 10 heliospheric parameters exhibit positive long-range correlations with multifractal behavior.APCs y acuerdos transformativos 2022, Springer Natur

On the Convergence of the Milky Way and M31 Kinematics from Cosmological Simulations

The kinematics of the Milky Way (MW) and M31, the dominant galaxies in the Local Group (LG), can be used to estimate the LG total mass. New results on the M31 proper motion have recently been used to improve that estimate. Those results are based on kinematic priors that are sometimes guided and evaluated using cosmological N-body simulations. However, the kinematic properties of simulated LG analogues could be biased due to the effective power spectrum truncation induced by the small size of the parent simulation. Here we explore the dependence of LG kinematics on the simulation box size to argue that cosmological simulations need a box size on the order of 1 Gpc in order to claim convergence on the LG kinematic properties. Using a large enough simulation, we find M31 tangential and radial velocities relative to the MW to be in the range $v_{\mathrm {tan}}=105^{+94}_{-59}$ km/s and $v_{\mathrm {rad}}=-108^{+68}_{-81}$ km/s, respectively. This study highlights that LG kinematics derived from N-body simulations have to be carefully interpreted taking into account the size of the parent simulation.Comment: 7 pages, 4 figures, Accepted for publication in Ap

Linking cosmic ray intensities to cutoff rigidity through multifractal detrented fluctuation analysis

We use multifractal detrented fluctuation analysis (MFDFA) to investigate the relationship between magnetic rigidity or ”cutoff rigidity” and the variability and multifractal behavior in the time series of the cosmic ray flux on Earth, which is detected by neutron monitors on the Earth's surface. Because the cutoff rigidity depends strongly on the geographical latitude of the detectors, not all detectors produce equal cosmic ray counts. Our results indicate that there is some bias in the chaotic nature of the cosmic ray series associated with the latitude of the monitoring stations. We obtain an important relationship between the cutoff rigidity (R) for different behaviors and the Hurst exponent of the series corresponding to the counts at the neutron monitor stations. In particular, an inverse relationship is observed with higher rigidity corresponding to a lower Hurst exponent (H(q=a)=maR+Ba). In particular, for q=−10, considering all time series, the correlation coefficient is approximately 0.80, whereas the R-squared is 0.638, and the coefficients of the linear regression for this case are m=−0.0425±0.006 and b=0.8703±0.025. © 2022 Elsevier B.V