Aadarsh Raj Sharma, Lot Ram, Harshaa Suhaag, Dipjyoti Patgiri, Lauriane Soret, Jean-Claude Gerard, Ian R. Thomas, Ann Carine Vandaele, Sumanta Sarkhel
We report, for the first time, the impact of an interplanetary coronal mass ejection (ICME) on the recently discovered O($^1$S) 557.7 nm dayglow emission in the Martian atmosphere. Although there are only a few studies on the seasonal variation are available in the literature, the impact of ICME on 557.7 nm dayglow emission has not been investigated so far. Using the instruments aboard ExoMars-TGO and MAVEN spacecrafts, we show that the primary emission peak (75-80 km) remains unaffected during the ICME event compared to quiet-times. However, a noticeable enhancement has been observed in the brightness of secondary emission peak (110-120 km) and the upper altitude region (140-180 km). The enhancement is attributed to the increased solar electrons and X-ray fluxes, augmenting the electron-impact process and causing the enhancement in the brightness. These analyses have an implication to comprehend the role of intense solar transients like ICME on the Martian dayglow emissions.
{"title":"A case study on the impact of interplanetary coronal mass ejection on the Martian O(1S) 557.7 nm dayglow emission using ExoMars TGO/NOMAD-UVIS observations: First Results","authors":"Aadarsh Raj Sharma, Lot Ram, Harshaa Suhaag, Dipjyoti Patgiri, Lauriane Soret, Jean-Claude Gerard, Ian R. Thomas, Ann Carine Vandaele, Sumanta Sarkhel","doi":"arxiv-2408.01045","DOIUrl":"https://doi.org/arxiv-2408.01045","url":null,"abstract":"We report, for the first time, the impact of an interplanetary coronal mass\u0000ejection (ICME) on the recently discovered O($^1$S) 557.7 nm dayglow emission\u0000in the Martian atmosphere. Although there are only a few studies on the\u0000seasonal variation are available in the literature, the impact of ICME on 557.7\u0000nm dayglow emission has not been investigated so far. Using the instruments\u0000aboard ExoMars-TGO and MAVEN spacecrafts, we show that the primary emission\u0000peak (75-80 km) remains unaffected during the ICME event compared to\u0000quiet-times. However, a noticeable enhancement has been observed in the\u0000brightness of secondary emission peak (110-120 km) and the upper altitude\u0000region (140-180 km). The enhancement is attributed to the increased solar\u0000electrons and X-ray fluxes, augmenting the electron-impact process and causing\u0000the enhancement in the brightness. These analyses have an implication to\u0000comprehend the role of intense solar transients like ICME on the Martian\u0000dayglow emissions.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141969667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kyung-Eun Choi, Oleksiy Agapitov, Lucas Colomban, John W. Bonnell, Forrest Mozer, Richard D. Sydora, Nour Raouafi, Thierry Dudok de Wit
In the interplanetary space solar wind plasma, whistler waves are observed in a wide range of heliocentric distance (from ~20 solar radii (RS) to Jupiter's orbit). They are known to interact with solar wind suprathermal electrons (strahl and halo) and to regulate the solar wind heat flux through scattering the strahl electrons. We present the results of applying the technique to determine the whistler wave propagation direction to the spectral data continuously collected by the FIELDS instruments aboard Parker Solar Probe (PSP). The technique was validated based on the results obtained from burst mode magnetic and electric field waveform data collected during Encounter 1. We estimated the effective length of the PSP electric field antennas (EFI) for a variety of solar wind conditions in the whistler wave frequency range and utilized these estimates for determining the whistler wave properties during PSP Encounters 1-11. Our findings show that (1) the enhancement of the whistler wave occurrence rate and wave amplitudes observed between 25-35 RS is predominantly due to the sunward propagating whistler waves population associated with the switchback-related magnetic dips; (2) the anti-sunward or counter-propagating cases are observed at 30-40 RS; (3) between 40-50 RS, sunward and anti-sunward whistlers are observed with comparable occurrence rates; and (4) almost no sunward or counter-propagating whistlers were observed at heliocentric distances above 50 RS.
{"title":"Whistler waves in the young solar wind: statistics of amplitude and propagation direction from Parker Solar Probe Encounters 1-11","authors":"Kyung-Eun Choi, Oleksiy Agapitov, Lucas Colomban, John W. Bonnell, Forrest Mozer, Richard D. Sydora, Nour Raouafi, Thierry Dudok de Wit","doi":"arxiv-2408.00736","DOIUrl":"https://doi.org/arxiv-2408.00736","url":null,"abstract":"In the interplanetary space solar wind plasma, whistler waves are observed in\u0000a wide range of heliocentric distance (from ~20 solar radii (RS) to Jupiter's\u0000orbit). They are known to interact with solar wind suprathermal electrons\u0000(strahl and halo) and to regulate the solar wind heat flux through scattering\u0000the strahl electrons. We present the results of applying the technique to\u0000determine the whistler wave propagation direction to the spectral data\u0000continuously collected by the FIELDS instruments aboard Parker Solar Probe\u0000(PSP). The technique was validated based on the results obtained from burst\u0000mode magnetic and electric field waveform data collected during Encounter 1. We\u0000estimated the effective length of the PSP electric field antennas (EFI) for a\u0000variety of solar wind conditions in the whistler wave frequency range and\u0000utilized these estimates for determining the whistler wave properties during\u0000PSP Encounters 1-11. Our findings show that (1) the enhancement of the whistler\u0000wave occurrence rate and wave amplitudes observed between 25-35 RS is\u0000predominantly due to the sunward propagating whistler waves population\u0000associated with the switchback-related magnetic dips; (2) the anti-sunward or\u0000counter-propagating cases are observed at 30-40 RS; (3) between 40-50 RS,\u0000sunward and anti-sunward whistlers are observed with comparable occurrence\u0000rates; and (4) almost no sunward or counter-propagating whistlers were observed\u0000at heliocentric distances above 50 RS.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141882644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. -L. Zhao, G. P. Zank, M. Opher, B. Zieger, H. Li, V. Florinski, L. Adhikari, X. Zhu, M. Nakanotani
Magnetic field fluctuations measured in the heliosheath by the Voyager spacecraft are often characterized as compressible, as indicated by a strong fluctuating component parallel to the mean magnetic field. However, the interpretation of the turbulence data faces the caveat that the standard Taylor hypothesis is invalid because the solar wind flow velocity in the heliosheath becomes subsonic and slower than the fast magnetosonic speed, given the contributions from hot pickup ions in the heliosheath. We attempt to overcome this caveat by introducing a 4D frequency wavenumber spectral modeling of turbulence, which is essentially a decomposition of different wave modes following their respective dispersion relations. Isotropic Alfven and fast mode turbulence are considered to represent the heliosheath fluctuations. We also include two dispersive fast wave modes derived from a three-fluid theory. We find that (1) magnetic fluctuations in the inner heliosheath are less compressible than previously thought. An isotropic turbulence spectral model with about 1/4 in compressible fluctuation power is consistent with the observed magnetic compressibility in the heliosheath; (2) the hot pickup ion component and the relatively cold solar wind ions induce two dispersive fast magnetosonic wave branches in the perpendicular propagation limit. Pickup ion fast wave may account for the spectral bump near the proton gyrofrequency in the observable spectrum; (3) it is possible that the turbulence wavenumber spectrum is not Kolmogorov-like although the observed frequency spectrum has a -5/3 power law index, depending on the partitioning of power among the various wave modes, and this partitioning may change with wavenumber.
{"title":"Turbulence, Waves, and Taylor's Hypothesis for Heliosheath Observations","authors":"L. -L. Zhao, G. P. Zank, M. Opher, B. Zieger, H. Li, V. Florinski, L. Adhikari, X. Zhu, M. Nakanotani","doi":"arxiv-2407.21673","DOIUrl":"https://doi.org/arxiv-2407.21673","url":null,"abstract":"Magnetic field fluctuations measured in the heliosheath by the Voyager\u0000spacecraft are often characterized as compressible, as indicated by a strong\u0000fluctuating component parallel to the mean magnetic field. However, the\u0000interpretation of the turbulence data faces the caveat that the standard Taylor\u0000hypothesis is invalid because the solar wind flow velocity in the heliosheath\u0000becomes subsonic and slower than the fast magnetosonic speed, given the\u0000contributions from hot pickup ions in the heliosheath. We attempt to overcome\u0000this caveat by introducing a 4D frequency wavenumber spectral modeling of\u0000turbulence, which is essentially a decomposition of different wave modes\u0000following their respective dispersion relations. Isotropic Alfven and fast mode\u0000turbulence are considered to represent the heliosheath fluctuations. We also\u0000include two dispersive fast wave modes derived from a three-fluid theory. We\u0000find that (1) magnetic fluctuations in the inner heliosheath are less\u0000compressible than previously thought. An isotropic turbulence spectral model\u0000with about 1/4 in compressible fluctuation power is consistent with the\u0000observed magnetic compressibility in the heliosheath; (2) the hot pickup ion\u0000component and the relatively cold solar wind ions induce two dispersive fast\u0000magnetosonic wave branches in the perpendicular propagation limit. Pickup ion\u0000fast wave may account for the spectral bump near the proton gyrofrequency in\u0000the observable spectrum; (3) it is possible that the turbulence wavenumber\u0000spectrum is not Kolmogorov-like although the observed frequency spectrum has a\u0000-5/3 power law index, depending on the partitioning of power among the various\u0000wave modes, and this partitioning may change with wavenumber.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arnold Yang, Indie Desiderio-Sloane, Grant David Meadors
Spurious solar-wind effects are a potential noise source in the measurements of the future Laser Interferometer Space Antenna (LISA). Comparative models are used to predict the possible impact of this noise factor and estimate spurious solar-wind effects on acceleration noise in LISA Pathfinder (LPF). Data from NASA's Advanced Composition Explorer (ACE), situated at the L1 Lagrange point, served as a reliable source of solar-wind data. The data sets were compared over the 114-day time period from March 1, 2016 to June 23, 2016. To evaluate these effects, the data from both satellites were formatted, gap-filled, and adapted for comparison, and a coherence plot comparing the results of the Fast Fourier Transformations. The coherence plot suggested that solar-wind had a minuscule effect on the LPF, and higher frequency coherence (LISA's main observing band) can be attributed to random chance correlation. This result indicates that measurable correlation due to solar-wind noise over 3-month timescales can be ruled out as a noise source. This is encouraging, although another source of noise from the sun, solar irradiance pressure, is estimated to have a more significant effect and has yet to be analyzed.
{"title":"Spurious Solar-Wind Effects on Acceleration Noise in LISA Pathfinder","authors":"Arnold Yang, Indie Desiderio-Sloane, Grant David Meadors","doi":"arxiv-2407.21774","DOIUrl":"https://doi.org/arxiv-2407.21774","url":null,"abstract":"Spurious solar-wind effects are a potential noise source in the measurements\u0000of the future Laser Interferometer Space Antenna (LISA). Comparative models are\u0000used to predict the possible impact of this noise factor and estimate spurious\u0000solar-wind effects on acceleration noise in LISA Pathfinder (LPF). Data from\u0000NASA's Advanced Composition Explorer (ACE), situated at the L1 Lagrange point,\u0000served as a reliable source of solar-wind data. The data sets were compared\u0000over the 114-day time period from March 1, 2016 to June 23, 2016. To evaluate\u0000these effects, the data from both satellites were formatted, gap-filled, and\u0000adapted for comparison, and a coherence plot comparing the results of the Fast\u0000Fourier Transformations. The coherence plot suggested that solar-wind had a\u0000minuscule effect on the LPF, and higher frequency coherence (LISA's main\u0000observing band) can be attributed to random chance correlation. This result\u0000indicates that measurable correlation due to solar-wind noise over 3-month\u0000timescales can be ruled out as a noise source. This is encouraging, although\u0000another source of noise from the sun, solar irradiance pressure, is estimated\u0000to have a more significant effect and has yet to be analyzed.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anwesha Maharana, Luis Linan, Stefaan Poedts, Jasmina Magdalenic
Rising concerns about the impact of space weather-related disruptions demand modelling and reliable forecasting of coronal mass ejection (CME) impacts. In this study, we demonstrate the application of the modified Miller-Turner (mMT) model implemented in EUropean Heliospheric FORecasting Information Asset (EUHFORIA), to forecast the geo-effectiveness of observed coronal mass ejection (CME) events in the heliosphere. The goal is to develop a model that not only has a global geometry to improve overall forecasting but is also fast enough for operational space weather forecasting. We test the original full torus implementation and introduce a new three-fourth Torus version called the Horseshoe CME model. This new model has a more realistic CME geometry, and it overcomes the inaccuracies of the full torus geometry. We constrain the torus geometrical and magnetic field parameters using observed signatures of the CMEs before, during, and after the eruption. The assessment of the model's capability to predict the most important Bz component is performed using the advanced Dynamic Time Warping technique. The Horseshoe model prediction of CME arrival time and geo-effectiveness for both validation events compare well to the observations and are weighed with the results obtained with the spheromak and FRi3D models that were already available in EUHFORIA. The runtime of the Horseshoe model simulations is close to that of the spheromak model, which is suitable for operational space weather forecasting. Yet, the capability of the magnetic field prediction at 1~AU of the Horseshoe model is close to that of the FRi3D model. In addition, we demonstrate that the Horseshoe CME model can be used for simulating successive CMEs in EUHFORIA, overcoming a limitation of the FRi3D model.
{"title":"Toroidal modified Miller-Turner CME model in EUHFORIA: II. Validation and comparison with flux rope and spheromak","authors":"Anwesha Maharana, Luis Linan, Stefaan Poedts, Jasmina Magdalenic","doi":"arxiv-2408.03882","DOIUrl":"https://doi.org/arxiv-2408.03882","url":null,"abstract":"Rising concerns about the impact of space weather-related disruptions demand\u0000modelling and reliable forecasting of coronal mass ejection (CME) impacts. In\u0000this study, we demonstrate the application of the modified Miller-Turner (mMT)\u0000model implemented in EUropean Heliospheric FORecasting Information Asset\u0000(EUHFORIA), to forecast the geo-effectiveness of observed coronal mass ejection\u0000(CME) events in the heliosphere. The goal is to develop a model that not only\u0000has a global geometry to improve overall forecasting but is also fast enough\u0000for operational space weather forecasting. We test the original full torus\u0000implementation and introduce a new three-fourth Torus version called the\u0000Horseshoe CME model. This new model has a more realistic CME geometry, and it\u0000overcomes the inaccuracies of the full torus geometry. We constrain the torus\u0000geometrical and magnetic field parameters using observed signatures of the CMEs\u0000before, during, and after the eruption. The assessment of the model's\u0000capability to predict the most important Bz component is performed using the\u0000advanced Dynamic Time Warping technique. The Horseshoe model prediction of CME\u0000arrival time and geo-effectiveness for both validation events compare well to\u0000the observations and are weighed with the results obtained with the spheromak\u0000and FRi3D models that were already available in EUHFORIA. The runtime of the\u0000Horseshoe model simulations is close to that of the spheromak model, which is\u0000suitable for operational space weather forecasting. Yet, the capability of the\u0000magnetic field prediction at 1~AU of the Horseshoe model is close to that of\u0000the FRi3D model. In addition, we demonstrate that the Horseshoe CME model can\u0000be used for simulating successive CMEs in EUHFORIA, overcoming a limitation of\u0000the FRi3D model.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141969665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. E. Stawarz, P. A. Muñoz, N. Bessho, R. Bandyopadhyay, T. K. M. Nakamura, S. Eriksson, D. Graham, J. Büchner, A. Chasapis, J. F. Drake, M. A. Shay, R. E. Ergun, H. Hasegawa, Yu. V. Khotyaintsev, M. Swisdak, F. Wilder
Alongside magnetic reconnection, turbulence is another fundamental nonlinear plasma phenomenon that plays a key role in energy transport and conversion in space and astrophysical plasmas. From a numerical, theoretical, and observational point of view there is a long history of exploring the interplay between these two phenomena in space plasma environments; however, recent high-resolution, multi-spacecraft observations have ushered in a new era of understanding this complex topic. The interplay between reconnection and turbulence is both complex and multifaceted, and can be viewed through a number of different interrelated lenses - including turbulence acting to generate current sheets that undergo magnetic reconnection (turbulence-driven reconnection), magnetic reconnection driving turbulent dynamics in an environment (reconnection-driven turbulence) or acting as an intermediate step in the excitation of turbulence, and the random diffusive/dispersive nature of magnetic field lines embedded in turbulent fluctuations enabling so-called stochastic reconnection. In this paper, we review the current state of knowledge on these different facets of the interplay between turbulence and reconnection in the context of collisionless plasmas, such as those found in many near-Earth astrophysical environments, from a theoretical, numerical, and observational perspective. Particular focus is given to several key regions in Earth's magnetosphere - Earth's magnetosheath, magnetotail, and Kelvin-Helmholtz vortices on the magnetopause flanks - where NASA's Magnetospheric Multiscale mission has been providing new insights on the topic.
{"title":"The Interplay Between Collisionless Magnetic Reconnection and Turbulence","authors":"J. E. Stawarz, P. A. Muñoz, N. Bessho, R. Bandyopadhyay, T. K. M. Nakamura, S. Eriksson, D. Graham, J. Büchner, A. Chasapis, J. F. Drake, M. A. Shay, R. E. Ergun, H. Hasegawa, Yu. V. Khotyaintsev, M. Swisdak, F. Wilder","doi":"arxiv-2407.20787","DOIUrl":"https://doi.org/arxiv-2407.20787","url":null,"abstract":"Alongside magnetic reconnection, turbulence is another fundamental nonlinear\u0000plasma phenomenon that plays a key role in energy transport and conversion in\u0000space and astrophysical plasmas. From a numerical, theoretical, and\u0000observational point of view there is a long history of exploring the interplay\u0000between these two phenomena in space plasma environments; however, recent\u0000high-resolution, multi-spacecraft observations have ushered in a new era of\u0000understanding this complex topic. The interplay between reconnection and\u0000turbulence is both complex and multifaceted, and can be viewed through a number\u0000of different interrelated lenses - including turbulence acting to generate\u0000current sheets that undergo magnetic reconnection (turbulence-driven\u0000reconnection), magnetic reconnection driving turbulent dynamics in an\u0000environment (reconnection-driven turbulence) or acting as an intermediate step\u0000in the excitation of turbulence, and the random diffusive/dispersive nature of\u0000magnetic field lines embedded in turbulent fluctuations enabling so-called\u0000stochastic reconnection. In this paper, we review the current state of\u0000knowledge on these different facets of the interplay between turbulence and\u0000reconnection in the context of collisionless plasmas, such as those found in\u0000many near-Earth astrophysical environments, from a theoretical, numerical, and\u0000observational perspective. Particular focus is given to several key regions in\u0000Earth's magnetosphere - Earth's magnetosheath, magnetotail, and\u0000Kelvin-Helmholtz vortices on the magnetopause flanks - where NASA's\u0000Magnetospheric Multiscale mission has been providing new insights on the topic.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Harry C. LewisImperial College London, Julia E. StawarzNorthumbria University, Lorenzo MatteiniImperial College London, Luca FranciNorthumbria University, Kristopher G. KleinUniversity of Arizona, Robert T. WicksNorthumbria University, Chadi S. SalemUniversity of California Berkeley, Timothy S. HorburyImperial College London, Joseph H. WangImperial College London
Plasma in the terrestrial magnetosheath is characterised by very weak particle-particle collisions, so kinetic microinstabilities are thought to be responsible for regulating the thermodynamics of the plasma. By exciting electromagnetic waves, these instabilities redistribute free energy in velocity space, moulding the velocity distribution function (VDF) into a lower energy state. In the high-beta magnetosheath, relatively small perturbations to the VDF can easily excite instabilities compared to in the low-beta inner heliosphere. Since magnetic fields cannot do work on the particles, electric fields mediate energy exchange between the electromagnetic field and the bulk fluid properties of the plasma. We investigate signatures of non-ideal energy conversion associated with turbulent fluctuations in the context of electron and ion temperature anisotropy-beta instabilities, utilising over 24 hours of data spread over 163 distinct intervals of in situ magnetosheath observations from Magnetospheric Multiscale (MMS). We find that average energy conversion into fluid flow is enhanced along instability boundaries, suggesting that turbulence is playing a role in how free energy is redistributed in the plasma. The work enables a quantification of the energetics which are associated with the role of kinetic microinstabilities in regulating collisionless plasma thermodynamics. This work provides insight into the open question of how specific plasma processes couple into the turbulent dynamics and ultimately lead to energy dissipation and particle energisation in collisionless plasmas.
{"title":"Turbulent Energy Conversion Associated with Kinetic Microinstabilities in Earth's Magnetosheath","authors":"Harry C. LewisImperial College London, Julia E. StawarzNorthumbria University, Lorenzo MatteiniImperial College London, Luca FranciNorthumbria University, Kristopher G. KleinUniversity of Arizona, Robert T. WicksNorthumbria University, Chadi S. SalemUniversity of California Berkeley, Timothy S. HorburyImperial College London, Joseph H. WangImperial College London","doi":"arxiv-2407.20844","DOIUrl":"https://doi.org/arxiv-2407.20844","url":null,"abstract":"Plasma in the terrestrial magnetosheath is characterised by very weak\u0000particle-particle collisions, so kinetic microinstabilities are thought to be\u0000responsible for regulating the thermodynamics of the plasma. By exciting\u0000electromagnetic waves, these instabilities redistribute free energy in velocity\u0000space, moulding the velocity distribution function (VDF) into a lower energy\u0000state. In the high-beta magnetosheath, relatively small perturbations to the\u0000VDF can easily excite instabilities compared to in the low-beta inner\u0000heliosphere. Since magnetic fields cannot do work on the particles, electric\u0000fields mediate energy exchange between the electromagnetic field and the bulk\u0000fluid properties of the plasma. We investigate signatures of non-ideal energy\u0000conversion associated with turbulent fluctuations in the context of electron\u0000and ion temperature anisotropy-beta instabilities, utilising over 24 hours of\u0000data spread over 163 distinct intervals of in situ magnetosheath observations\u0000from Magnetospheric Multiscale (MMS). We find that average energy conversion\u0000into fluid flow is enhanced along instability boundaries, suggesting that\u0000turbulence is playing a role in how free energy is redistributed in the plasma.\u0000The work enables a quantification of the energetics which are associated with\u0000the role of kinetic microinstabilities in regulating collisionless plasma\u0000thermodynamics. This work provides insight into the open question of how\u0000specific plasma processes couple into the turbulent dynamics and ultimately\u0000lead to energy dissipation and particle energisation in collisionless plasmas.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. E. Cordonnier, K. S. Obenberger, J. M. Holmes, G. B. Taylor, D. Vida
This paper presents the results of a nearly two year long campaign to detect and analyze meteor persistent trains (PTs) - self-emitting phenomena which can linger up to an hour after their parent meteor. The modern understanding of PTs has been primarily developed from the Leonid storms at the turn of the century; our goal was to assess the validity of these conclusions using a diverse sample of meteors with a wide range of velocities and magnitudes. To this end, year-round observations were recorded by the Widefield Persistent Train camera, 2nd edition (WiPT2) and were passed through a pipeline to filter out airplanes and flag potential meteors. These were classified by visual inspection based on the presence and duration of trains. Observed meteors were cross-referenced with the Global Meteor Network (GMN) database, which independently detects and calculates meteor parameters, enabling statistical analysis of PT-leaving meteors. There were 4726 meteors codetected by the GMN, with 636 of these leaving trains. Among these were a large population of slow, dim meteors that left PTs; these slower meteors had a greater train production rate relative to their faster counterparts. Unlike prior research, we did not find a clear magnitude cutoff or a strong association with fast meteor showers. Additionally, we note several interesting trends not previously reported, which include PT eligibility being primarily determined by a meteor's terminal height and an apparent dynamical origin dependence that likely reflects physical meteoroid properties.
{"title":"Not So Fast: A New Catalog of Meteor Persistent Trains","authors":"L. E. Cordonnier, K. S. Obenberger, J. M. Holmes, G. B. Taylor, D. Vida","doi":"arxiv-2407.18344","DOIUrl":"https://doi.org/arxiv-2407.18344","url":null,"abstract":"This paper presents the results of a nearly two year long campaign to detect\u0000and analyze meteor persistent trains (PTs) - self-emitting phenomena which can\u0000linger up to an hour after their parent meteor. The modern understanding of PTs\u0000has been primarily developed from the Leonid storms at the turn of the century;\u0000our goal was to assess the validity of these conclusions using a diverse sample\u0000of meteors with a wide range of velocities and magnitudes. To this end,\u0000year-round observations were recorded by the Widefield Persistent Train camera,\u00002nd edition (WiPT2) and were passed through a pipeline to filter out airplanes\u0000and flag potential meteors. These were classified by visual inspection based on\u0000the presence and duration of trains. Observed meteors were cross-referenced\u0000with the Global Meteor Network (GMN) database, which independently detects and\u0000calculates meteor parameters, enabling statistical analysis of PT-leaving\u0000meteors. There were 4726 meteors codetected by the GMN, with 636 of these\u0000leaving trains. Among these were a large population of slow, dim meteors that\u0000left PTs; these slower meteors had a greater train production rate relative to\u0000their faster counterparts. Unlike prior research, we did not find a clear\u0000magnitude cutoff or a strong association with fast meteor showers.\u0000Additionally, we note several interesting trends not previously reported, which\u0000include PT eligibility being primarily determined by a meteor's terminal height\u0000and an apparent dynamical origin dependence that likely reflects physical\u0000meteoroid properties.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chong-Chong HeANU, Benjamin D. WibkingMSU, Mark R. KrumholzANU
Mixed-frame formulations of radiation-hydrodynamics (RHD), where the radiation quantities are computed in an inertial frame but matter quantities are in a comoving frame, are advantageous because they admit algorithms that conserve energy and momentum to machine precision and combine more naturally with adaptive mesh techniques, since unlike pure comoving-frame methods they do not face the problem that radiation quantities must change frame every time a cell is refined or coarsened. However, implementing multigroup RHD in a mixed-frame formulation presents challenges due to the complexity of handling frequency-dependent interactions and the Doppler shift of radiation boundaries. In this paper, we introduce a novel method for multigroup RHD that integrates a mixed-frame formulation with a piecewise powerlaw approximation for frequency dependence within groups. This approach ensures the exact conservation of total energy and momentum while effectively managing the Lorentz transformation of group boundaries and evaluation of group-averaged opacities. Our method takes advantage of the locality of matter-radiation coupling, allowing the source term for $N_g$ frequency groups to be handled with simple equations with a sparse Jacobian matrix of size $N_g + 1$, which can be inverted with $O(N_g)$ complexity. This results in a computational complexity that scales linearly with $N_g$ and requires no more communication than a pure hydrodynamics update, making it highly efficient for massively parallel and GPU-based systems. We implement our method in the GPU-accelerated RHD code QUOKKA and demonstrate that it passes a wide range of numerical tests. We demonstrate that the piecewise powerlaw method shows significant advantages over traditional opacity averaging methods for handling rapidly variable opacities with modest frequency resolution.
{"title":"A novel numerical method for mixed-frame multigroup radiation-hydrodynamics with GPU acceleration implemented in the QUOKKA code","authors":"Chong-Chong HeANU, Benjamin D. WibkingMSU, Mark R. KrumholzANU","doi":"arxiv-2407.18304","DOIUrl":"https://doi.org/arxiv-2407.18304","url":null,"abstract":"Mixed-frame formulations of radiation-hydrodynamics (RHD), where the\u0000radiation quantities are computed in an inertial frame but matter quantities\u0000are in a comoving frame, are advantageous because they admit algorithms that\u0000conserve energy and momentum to machine precision and combine more naturally\u0000with adaptive mesh techniques, since unlike pure comoving-frame methods they do\u0000not face the problem that radiation quantities must change frame every time a\u0000cell is refined or coarsened. However, implementing multigroup RHD in a\u0000mixed-frame formulation presents challenges due to the complexity of handling\u0000frequency-dependent interactions and the Doppler shift of radiation boundaries.\u0000In this paper, we introduce a novel method for multigroup RHD that integrates a\u0000mixed-frame formulation with a piecewise powerlaw approximation for frequency\u0000dependence within groups. This approach ensures the exact conservation of total\u0000energy and momentum while effectively managing the Lorentz transformation of\u0000group boundaries and evaluation of group-averaged opacities. Our method takes\u0000advantage of the locality of matter-radiation coupling, allowing the source\u0000term for $N_g$ frequency groups to be handled with simple equations with a\u0000sparse Jacobian matrix of size $N_g + 1$, which can be inverted with $O(N_g)$\u0000complexity. This results in a computational complexity that scales linearly\u0000with $N_g$ and requires no more communication than a pure hydrodynamics update,\u0000making it highly efficient for massively parallel and GPU-based systems. We\u0000implement our method in the GPU-accelerated RHD code QUOKKA and demonstrate\u0000that it passes a wide range of numerical tests. We demonstrate that the\u0000piecewise powerlaw method shows significant advantages over traditional opacity\u0000averaging methods for handling rapidly variable opacities with modest frequency\u0000resolution.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High energy electrons carry much of a solar flare's energy. Therefore, understanding changes in electron beam distributions during their propagation is crucial. A key focus of this paper is how the co-spatial return current reduces the energy flux carried by these accelerated electrons. We systematically compute this reduction for various beam and plasma parameters relevant to solar flares. Our 1D model accounts for collisions between beam and plasma electrons, return current electric-field deceleration, thermalization in a warm target approximation, and runaway electron contributions. The results focus on the classical (Spitzer) regime, offering a valuable benchmark for energy flux reduction and its extent. Return current losses are only negligible for the lowest nonthermal fluxes. We calculate the conditions for return current losses to become significant and estimate the extent of the modification to the beam's energy flux density. We also calculate two additional conditions which occur for higher injected fluxes: (1) where runaway electrons become significant, and (2) where current-driven instabilities might become significant, requiring a model that self-consistently accounts for them. Condition (2) is relaxed and the energy flux losses are reduced in the presence of runaway electrons. All results are dependent on beam and co-spatial plasma parameters. We also examine the importance of the reflection of beam electrons by the return-current electric field. We show that the interpretation of a number of flares needs to be reviewed to account for the effects of return currents.
{"title":"Reduction of the downward energy flux of non-thermal electrons in the solar flare corona due to co-spatial return current losses","authors":"Meriem Alaoui, Gordon D. Holman, Marc Swisdak","doi":"arxiv-2407.17955","DOIUrl":"https://doi.org/arxiv-2407.17955","url":null,"abstract":"High energy electrons carry much of a solar flare's energy. Therefore,\u0000understanding changes in electron beam distributions during their propagation\u0000is crucial. A key focus of this paper is how the co-spatial return current\u0000reduces the energy flux carried by these accelerated electrons. We\u0000systematically compute this reduction for various beam and plasma parameters\u0000relevant to solar flares. Our 1D model accounts for collisions between beam and\u0000plasma electrons, return current electric-field deceleration, thermalization in\u0000a warm target approximation, and runaway electron contributions. The results\u0000focus on the classical (Spitzer) regime, offering a valuable benchmark for\u0000energy flux reduction and its extent. Return current losses are only negligible\u0000for the lowest nonthermal fluxes. We calculate the conditions for return\u0000current losses to become significant and estimate the extent of the\u0000modification to the beam's energy flux density. We also calculate two\u0000additional conditions which occur for higher injected fluxes: (1) where runaway\u0000electrons become significant, and (2) where current-driven instabilities might\u0000become significant, requiring a model that self-consistently accounts for them.\u0000Condition (2) is relaxed and the energy flux losses are reduced in the presence\u0000of runaway electrons. All results are dependent on beam and co-spatial plasma\u0000parameters. We also examine the importance of the reflection of beam electrons\u0000by the return-current electric field. We show that the interpretation of a\u0000number of flares needs to be reviewed to account for the effects of return\u0000currents.","PeriodicalId":501423,"journal":{"name":"arXiv - PHYS - Space Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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