Pablo S Moya

Pablo S Moya
University of Chile · Departamento de Física (Ciencias)

PhD in Physics

About

84
Publications
8,508
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846
Citations
Introduction
PhD in Physics from the University of Chile (2011). In my thesis I studied the acceleration and heating of the solar wind. Postdoc at NASA Goddard (2013-2015). Currently Assistant Professor at the Dept of Physics of the University of Chile. My research interests include kinetic theory of plasma waves, the study of kinetic processes on space and astrophysical plasmas, and solar wind turbulence. I'm also interested in quantum and relativistic plasmas, and interdisciplinary problems in geophysics
Additional affiliations
November 2017 - present
University of Chile
Position
  • Professor (Assistant)
October 2017 - present
University of Chile
Position
  • Professor (Assistant)
April 2015 - October 2017
University of Chile
Position
  • Instructor
Education
March 2007 - October 2011
University of Chile
Field of study
  • Physics
March 2003 - December 2006
University of Chile
Field of study
  • Physics

Publications

Publications (84)
Article
Full-text available
Electron velocity distributions in the solar wind are known to have field-aligned skewness, which has been characterized by the presence of secondary populations such as the halo and strahl. Skewness may provide energy for the excitation of electromagnetic instabilities, such as the whistler heat flux instability (WHFI), which may play an important...
Article
Full-text available
Among the fundamental and most challenging problems of laboratory, space, and astrophysical plasma physics is to understand the relaxation processes of nearly collisionless plasmas toward quasi-stationary states and the resultant states of electromagnetic plasma turbulence. Recently, it has been argued that solar wind plasma β and temperature aniso...
Article
Full-text available
Kappa distributions (or κ-like distributions) represent a robust framework to characterize and understand complex phenomena with high degrees of freedom, as turbulent systems, using non-extensive statistical mechanics. Here we consider a coupled map lattice Langevin based model to analyze the relation of a turbulent flow, with its spatial scale dyn...
Article
Full-text available
There is wide observational evidence that electron velocity distribution functions (eVDF) observed in the solar wind generally present enhanced tails and field-aligned skewness. These properties may induce the excitation of electromagnetic perturbations through the whistler heat-flux instability (WHFI), that may contribute to a non-collisional regu...
Article
Full-text available
Interactions between plasma particles and electromagnetic waves play a crucial role in the dynamics and regulation of the state of space environments. From plasma physics theory, the characteristics of the waves and their interactions with the plasma strongly depend on the composition of the plasma, among other factors. In the case of the Earth's m...
Article
Full-text available
The electron firehose instabilities are among the most studied kinetic instabilities, especially in the context of space plasmas, whose dynamics is mainly controlled by collisionless wave–particle interactions. This paper undertakes a comparative analysis of the aperiodic electron firehose instabilities excited either by the anisotropic temperature...
Preprint
Full-text available
The electron firehose instabilities are among the most studied kinetic instabilities, especially in the context of space plasmas, whose dynamics is mainly controlled by collisionless wave-particle interactions. This paper undertakes a comparative analysis of the aperiodic electron firehose instabilities excited either by the anisotropic temperature...
Article
Full-text available
We focus on characterizing the high-energy emission mechanisms of blazars by analyzing the variability in the radio band of the light curves of more than a thousand sources. We are interested in assigning complexity parameters to these sources, modeling the time series of the light curves with the method of the Horizontal Visibility Graph (HVG), wh...
Preprint
Full-text available
Interactions between plasma particles and electromagnetic waves play a crucial role in the dynamics and regulation of the state of space environments. From plasma physics theory, the characteristics of the waves and their interactions with the plasma strongly depend on the composition of the plasma, among other factors. In the case of the Earth’s m...
Preprint
Full-text available
{We focus on characterizing the high-energy emission mechanisms of blazars by analyzing the variability in the radio band of the light curves of more than a thousand sources. We are interested in assigning complexity parameters to these sources, modeling the time series of the light curves with the method of the Horizontal Visibility Graph (HVG), w...
Preprint
Full-text available
There is wide observational evidence that electron velocity distribution functions (eVDF) observed in the solar wind generally present enhanced tails and field-aligned skewness. These properties may induce the excitation of electromagnetic perturbations through the whistler heat-flux instability (WHFI), that may contribute to a non-collisional regu...
Preprint
Full-text available
Among the fundamental and most challenging problems of laboratory, space, and astrophysical plasma physics is to understand the relaxation processes of nearly collisionless plasmas toward quasi-stationary states; and the resultant states of electromagnetic plasma turbulence. Recently, it has been argued that solar wind plasma $\beta$ and temperatur...
Preprint
Full-text available
Electron velocity distributions in the solar wind are known to have field-aligned skewness, which has been characterized by the presence of secondary populations such as the halo and strahl. Skewness may provide energy for the excitation of electromagnetic instabilities, such as the whistler heat-flux instability (WHFI), that may play an important...
Article
Full-text available
Using a time series of geomagnetic storm events between 1957 and 2019, obtained by selecting storms where $D_\text{st} < -50$ nT, we have analyzed the probability of occurrence of moderate, intense and severe events. Considering that geomagnetic storms can be modeled as stochastic processes with a log-normal probability distribution over their mini...
Chapter
Full-text available
In this chapter we focus on the recent progress made on numerical analysis and tools facilitating the investigation of dispersion and stability of anisotropic Kappa distributed plasmas. Plasma waves and fluctuations are directly dependent on the non-thermal features of the particle velocity distributions, and understanding their properties is a pri...
Article
Full-text available
One of the fundamental open questions in plasma physics is the role of non-thermal particles distributions in poorly collisional plasma environments, a system that is commonly found throughout the Universe, e.g., the solar wind and the Earth’s magnetosphere correspond to natural plasma physics laboratories in which turbulent phenomena can be studie...
Preprint
Full-text available
One of the fundamental open questions in plasma physics is the role of non-thermal particles distributions in poorly collisional plasma environments, a system commonly found throughout the Universe, e.g. the solar wind and the Earth’s magnetosphere correspond to natural plasma physics laboratories in which turbulent phenomena can be studied. Our st...
Article
Full-text available
Turbulence in space plasmas usually exhibits two regimes separated by a spectral break that divides the so called inertial and kinetic ranges. Large scale magnetic fluctuations are dominated by non-linear MHD wave-wave interactions following a −5/3 or −2 slope power-law spectrum. After the break, at scales in which kinetic effects take place, the m...
Article
Full-text available
One of the most striking properties of Kinetic Alfvén Waves (KAW) is that, unlike the also Alfvénic Electromagnetic Ion Cyclotron (EMIC) waves, these waves are right-hand polarized in the plasma frame. In particular, this signature property is key for the identification of KAW from in situ measurements of plasma waves. From the theoretical point of...
Preprint
Full-text available
One of the most striking properties of Kinetic Alfv\'en Waves (KAW) is that, unlike the also Alfv\'enic Electromagnetic Ion Cyclotron (EMIC) waves, these waves are right-hand polarized in the plasma frame. In particular, this signature property is key for the identification of KAW from in situ measurements of plasma waves. From the theoretical poin...
Article
Full-text available
The Earth's magnetosphere represents a natural plasma laboratory that allows us to study the behavior of particle distribution functions in the absence of Coulomb collisions, typically described by the kappa distributions. We have investigated the properties of these functions for ions and electrons in different magnetospheric regions, thereby maki...
Preprint
Full-text available
Many non-pharmaceutical interventions (NPI) have been implemented in several countries to prevent and mitigate the COVID-19 pandemic. In spite of the emergence of vaccines that mitigate illness and death, no effective measures exist to control the contagion. Testing, tracing, and isolation (TTI) in conjunction with disciplined social distancing wer...
Preprint
Full-text available
The Earth's magnetosphere represents a natural plasma laboratory that allows us to study the behavior of particle distribution functions in the absence of Coulomb collisions, typically described by the Kappa distributions. We have investigated the properties of these functions for ions and electrons in different magnetospheric regions, thereby maki...
Article
Full-text available
Kappa distributions are ubiquitous in space and astrophysical poorly collisional plasmas, such as the solar wind, suggesting that microscopic and macroscopic properties of these non-equilibrium plasmas are highly conditioned by the wave-particle interactions. The present work addresses the evolution of anisotropic bi-Kappa (or bi-κ-)distributions o...
Preprint
Full-text available
Kappa distributions are ubiquitous in space and astrophysical poorly collisional plasmas, such as the solar wind, suggesting that microscopic and macroscopic properties of these non-equilibrium plasmas are highly conditioned by the wave-particle interactions. The present work addresses the evolution of anisotropic bi-Kappa (or bi-κ-)distributions o...
Preprint
Full-text available
Turbulence in space plasmas usually exhibits two distinct regimes separated by a spectral break that divides the inertial and kinetic ranges in which wave-wave or wave-particle interactions dominate, respectively. Large scale fluctuations are dominated by MHD non-linear wave-wave interactions following a-5/3 or-3/2 slope power-law spectrum, that su...
Article
Full-text available
Heat transport in the solar wind is dominated by suprathermal electron populations, i.e., a tenuous halo and a field-aligned beam/strahl, with high energies and antisunward drifts along the magnetic field. Their evolution may offer plausible explanations for the rapid decrease of the heat flux with the solar wind expansion, and self-generated insta...
Article
Wave-particle interactions are believed to be one of the most important kinetic processes regulating the heating and acceleration of solar wind plasma. One possible explanation for the observed preferential heating of alpha (He +2) ions relies on a process similar to a second-order Fermi acceleration mechanism. In this model, heavy ions are able to...
Article
Based on discussions held at a workshop in Bra-Pollenzo, Italy, this paper elaborates upon 19 outstanding questions of plasma physics in the Earth's magnetosphere. The questions are grouped according to (a) driving processes, (b) radiation belt and ring current issues, (c) auroral physics, (d) internal plasma processes, and (e) magnetosphere-ionosp...
Preprint
Full-text available
The heat transport in the solar wind mainly involves the electron strahl population beaming along the local magnetic field. The rapid non-adiabatic decrease of the heat flux with the collisionless expansion of the solar wind is believed to be self-consistently controlled by the electron beam-plasma (or heat-flux) instabilities. However, multiple he...
Article
Full-text available
Forecasting relativistic electron fluxes at geostationary Earth orbit (GEO) has been a long term goal of the scientific community, and significant advances have been made in the past, but the relation to the interior of the radiation belts, that is, to lower L‐shells is still not clear. In this work we have identified 60 relativistic electron enhan...
Preprint
Full-text available
During the current COVID-19 pandemic it is imperative to give early warnings to reduce mortality. However, non-specialist such as authorities and the general population face several problems to understand the real thread of this pandemic, and under/overestimation of its risk are a commonplace in the press and social media. Here we define an index,...
Preprint
Full-text available
Depending on the physical conditions involved the beam plasma systems may reveal new unstable regimes triggered by the wave instabilities of different nature. We show through linear theory and numerical simulations the existence of an aperiodic electromagnetic instability which solely develops and control the stability of two symmetric plasma popul...
Article
Full-text available
Ultrarelativistic electron remnant belts are frequently observed at low $L$-shells between the inner belt and a re-forming outer belt following geomagnetic disturbances that led to a dropout of electron fluxes at higher radial distances from the Earth. Using wave, particle, and plasma measurements from the Van Allen Probes and Pc3-Pc5 ULF wave data...
Article
Full-text available
Ultrarelativistic electron remnant belts appear frequently following geomagnetic disturbances and are located in‐between the inner radiation belt and a reforming outer belt. As remnant belts are relatively stable, here we explore the importance of hiss and electromagnetic ion cyclotron waves in controlling the observed decay rates of remnant belt u...
Article
We have studied turbulent plasma as a complex system applying the method known as Horizontal Visibility Graph (HVG) to obtain the Kullback-Leibler Divergence (KLD) as a first approach to characterize the reversibility of the time series of the magnetic fluctuations. For this, we have developed the method on Particle In Cell (PIC) simulations for a...
Conference Paper
Geomagnetic storms can be modeled as stochastic processes with log-normal probability distribution function over their minimum Dst index value measured during the main phase of each event. Considering a time series of geomagnetic storm events between 1957 and 2019 we have analyzed the probability of occurrence of small, moderate, strong and extreme...
Article
In this work we have analyzed turbulent plasma in the kinetic scale by the characterization of magnetic fluctuations time series. Considering numerical Particle-In-Cell (PIC) simulations we apply a method known as MultiFractal Detrended Fluctuation Analysis (MFDFA) to study the fluctuations of solar-wind-like plasmas in thermodynamic equilibrium (r...
Article
An interesting problem in plasma physics, when approached from the point of view of Statistical Mechanics is to obtain properties of collisionless plasmas, which are described by the Vlasov equation. Through what we call the Ehrenfest procedure, which uses statistical mechanical relations we obtain expectation value relations for arbitrary observab...
Article
We report the first results from particle-in-cell simulations of the fast-growing aperiodic electron firehose instability driven by the anisotropic bi-Kappa distributed electrons. Such electrons characterize space plasmas, e.g., solar wind and planetary magnetospheres. Predictions made by the linear theory for full wave-frequency and wave-vector sp...
Article
Full-text available
Using data from DMSP 16-18, NOAA 15-19, and METOP 1-2 satellites we reconstructed for the first time a two-dimensional statistical distribution of plasma pressure in the inner magnetosphere during the 1 June 2013 ge-omagnetic storm with time resolution of 6 hours. Simultaneously, we used the data from Van Allen Probes and THEMIS missions to obtain...
Article
Full-text available
Shortly after the launch of the Van Allen Probes, a new three-belt con- figuration of the electron radiation belts was reported. Using data between September 2012 and November 2017, we have identified 30 three-belt events and found that about 18% of geomagnetic storms result in such configuration. Based on the identified events, we evaluated some c...
Article
Full-text available
We have analyzed the role of auroral processes in the formation of the outer radiation belt, considering that the main part of the auroral oval maps to the outer part of the ring current, instead of the plasma sheet as is commonly postulated. In this approach, the outer ring current is the region where transverse magnetospheric currents close insid...
Article
We use kappa distributions to model thousands of ion and electron flux spectra along the plasma sheet, and analyze the variation of the spectral index κ and the temperature T in this region. We find that κ distributions are ubiquitous and fit well ion and electron flux spectra during quiet times, and during the expansion and recovery phases of subs...
Preprint
Full-text available
It is well--known that when magnetic monopoles are introduced in plasma equations the propagation of electromagnetic waves is modified. This occurs because of Maxwell equations acquire a symmetrical structure due to the existence of electric and magnetic charge current densities. In this work we study the nonlinear phenomena of ponderomotive forces...
Article
Full-text available
The construction of a relativistic thermodynamics theory is still controversial after more than 110 years. To the date there is no agreement on which set of relativistic transformations of thermodynamic quantities is the correct one, or if the problem even has a solution. Starting from Planck and Einstein, several authors have proposed their own re...
Article
The abundant reports on the existence of electromagnetic high-frequency fluctuations in space plasmas have increased the expectations that theoretical modelling may help understand their origins and implications (e.g., kinetic instabilities, dissipation, etc.). This paper presents an extended quasilinear approach of the electromagnetic electron cyc...
Article
Full-text available
Using Van Allen Probes ECT-REPT observations we performed a statistical study on the effect of geomagnetic storms on relativistic electrons fluxes in the outer radiation belt for 78 storms between September 2012 and June 2016. We found that the probability of enhancement, depletion and no change in flux values depends strongly on L and energy. Enha...
Conference Paper
Full-text available
We try to summarize results of experimental and theoretical works demonstrating the close connection of auroral phenomena with the processes of the outer radiation belt formation in the magnetosphere of the Earth. Anomalously high relativistic electron fluxes in the outer radiation belt are frequently named electrons-killers. Such electrons formed...
Chapter
Full-text available
In this work we present a tutorial overview of the excitation, propagation and absorption of linear plasma waves in collisionless, spatially uniform, multi-component, magnetized non-thermal plasma characterized by a kappa velocity distribution based on a Vlasov kinetic description. Although traditional plasma physics texts are replete with examples...
Article
The solar wind electron velocity distribution function (eVDF) exhibits a variety of non-thermal features that deviate from thermal equilibrium. These deviations from equilibrium provide a local source for electromagnetic fluctuation emissions, including the commonly observed electron whistler-cyclotron and firehose instabilities. We present a syste...
Article
Full-text available
A sufficiently large temperature anisotropy can sometimes drive various types of electromagnetic plasma micro-instabilities, which can play an important role in the dynamics of relativistic pair plasmas in space, astrophysics, and laboratory environments. Here, we provide a detailed description of the cyclotron instability of parallel propagating e...
Article
Full-text available
The observations in the solar wind, which are usually organized in a beta-anisotropy diagram, seem to be constrained by linear instability thresholds. Unexpectedly, under these quasi-stable conditions, there is a finite level of electromagnetic fluctuations. A relevant component of these fluctuations can be understood in terms of the electromagneti...
Article
Full-text available
Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and α-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion...
Article
Full-text available
We use audification of 0.092 s cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes > 0.1 nT near the ion gyrofrequency (∼0.1 Hz) with duration longer than 1 hr during 2008. We present one of the most common types of event for a case study and find it to be a proton-cyclotron wave storm, coinciding with highly radial...
Article
Full-text available
We perform 2.5D hybrid simulations with massless fluid electrons and kinetic particle-in-cell ions to study the temporal evolution of ion temperatures, temperature anisotropies, and velocity distribution functions in relation to the dissipation and turbulent evolution of a broadband spectrum of parallel and obliquely propagating Alfvén-cyclotron wa...
Article
Full-text available
Spontaneous fluctuations are a robust phenomenon of plasmas near equilibrium, which does not depend on the existence of instabilities, and their characterization provides valuable information about the role of the relativistic temperatures ##IMG## [http://ej.iop.org/images/0004-637X/810/2/103/apj518308ieqn1.gif] {$Tsim mc}^2$ in relativistic regime...
Article
Full-text available
We present Van Allen Probe B observations of azimuthally limited, antisymmetric, poloidal Pc 4 electric and magnetic field pulsations in the pre-midnight sector of the magnetosphere from 05:40 to 06:00 UT on 1 May 2013. Oscillation periods were similar for the magnetic and electric fields and proton fluxes. The flux of energetic protons exhibited a...
Article
We perform 2.5D hybrid simulations with massless fluid electrons and kinetic particle-in-cell ions to study the temporal evolution of ion temperatures, temperature anisotropies and velocity distribution functions in relation to the dissipation and turbulent evolution of a broad-band spectrum of parallel and obliquely propagating Alfv\'en-cyclotron...