Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4ec3
Laurel White, Michael McDonald, Steven W. Allen, Marshall W. Bautz, Michael Calzadilla, Gordon P. Garmire, Julie Hlavacek-Larrondo, Ralph Kraft, Adam B. Mantz, Taweewat Somboonpanyakul and Alexey Vikhlinin
With rapid improvements in the assembly of large samples of galaxy clusters, we are approaching the ability to study clusters at z ≳ 2. Evolutionary studies comparing these distant clusters to the clusters in our local Universe depend heavily on the reliability of low-redshift cluster samples, most of which are subject to X-ray selection effects, biasing them to relaxed, cool-core clusters. Here, we introduce the Cluster Evolutionary Reference Ensemble at Low-z (CEREAL) sample, composed of Chandra X-ray observations of 169 galaxy clusters that have been selected from the Planck Sunyaev–Zel’dovich catalog. CEREAL has a simple and well-understood selection function, spans an order of magnitude in mass at z ∼ 0.15, and has uniform, high-resolution X-ray follow-up. We present the full sample and provide results based on X-ray surface brightness properties, finding significantly more non-cool-core systems than in X-ray-selected samples. We use surface brightness concentration (cSB) as a proxy for cool-core strength and centroid shift (w) to measure dynamical state. Over the full sample, we find a cool-core (cSB > 0.075) fraction of , a strong cool-core (cSB > 0.155) fraction of , and a dynamically relaxed (w < 0.01) fraction of . We find no mass dependence in the fraction of clusters that appear relaxed or have cool cores. We quantify the rarity of X-ray-bright central point sources (Lnuc, 2−10 keV > 1043 erg s−1), finding them to be intrinsically rare ( % of massive, low-z clusters) with a notable increase in occurrence rate at the centers of cool cores.
{"title":"The Cluster Evolutionary Reference Ensemble at Low-z (CEREAL) Sample of Galaxy Clusters. I. X-Ray Morphological Properties and Demographics","authors":"Laurel White, Michael McDonald, Steven W. Allen, Marshall W. Bautz, Michael Calzadilla, Gordon P. Garmire, Julie Hlavacek-Larrondo, Ralph Kraft, Adam B. Mantz, Taweewat Somboonpanyakul and Alexey Vikhlinin","doi":"10.3847/1538-4357/ae4ec3","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4ec3","url":null,"abstract":"With rapid improvements in the assembly of large samples of galaxy clusters, we are approaching the ability to study clusters at z ≳ 2. Evolutionary studies comparing these distant clusters to the clusters in our local Universe depend heavily on the reliability of low-redshift cluster samples, most of which are subject to X-ray selection effects, biasing them to relaxed, cool-core clusters. Here, we introduce the Cluster Evolutionary Reference Ensemble at Low-z (CEREAL) sample, composed of Chandra X-ray observations of 169 galaxy clusters that have been selected from the Planck Sunyaev–Zel’dovich catalog. CEREAL has a simple and well-understood selection function, spans an order of magnitude in mass at z ∼ 0.15, and has uniform, high-resolution X-ray follow-up. We present the full sample and provide results based on X-ray surface brightness properties, finding significantly more non-cool-core systems than in X-ray-selected samples. We use surface brightness concentration (cSB) as a proxy for cool-core strength and centroid shift (w) to measure dynamical state. Over the full sample, we find a cool-core (cSB > 0.075) fraction of , a strong cool-core (cSB > 0.155) fraction of , and a dynamically relaxed (w < 0.01) fraction of . We find no mass dependence in the fraction of clusters that appear relaxed or have cool cores. We quantify the rarity of X-ray-bright central point sources (Lnuc, 2−10 keV > 1043 erg s−1), finding them to be intrinsically rare ( % of massive, low-z clusters) with a notable increase in occurrence rate at the centers of cool cores.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"109 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147519254","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}
Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4b32
Xin Sheng, Bennett Link, Matthew E. Caplan and Yuri Levin
We study the superfluid vortex motion in the neutron star inner crust through direct 3D simulations of the coupled dynamics of the vortex and the nuclear lattice. We demonstrate the pinning of an initially moving vortex to the lattice through the excitation of lattice vibrations and show that the efficiency of this process is higher for attractive than for repulsive nucleus–vortex interactions. We explore the unpinning of a vortex under the action of the applied Magnus force and find that it is influenced by multiple parameters, including the sign of the pinning force, the lattice orientation, composition, temperature, and the energy of the pinning to individual nuclei. In lattices with multiple grains, the unpinning transition is triggered inside the grains with weaker pinning, propagates along the vortex (mediated by the excited Kelvin waves), and crosses into grains with stronger pinning. This is likely to effectively decrease the critical force at which vortices unpin and to produce extended regions of unpinned vorticity. The shearing of the crust lattice (e.g., by a starquake) initiates the unpinning of the vortices that are crossing the slip plane. A close encounter of an unpinned vortex with a pinned vortex would cause the latter to unpin, perhaps initiating an unpinning avalanche of many vortices.
{"title":"Vortex Dynamics in the Neutron Star Inner Crust","authors":"Xin Sheng, Bennett Link, Matthew E. Caplan and Yuri Levin","doi":"10.3847/1538-4357/ae4b32","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4b32","url":null,"abstract":"We study the superfluid vortex motion in the neutron star inner crust through direct 3D simulations of the coupled dynamics of the vortex and the nuclear lattice. We demonstrate the pinning of an initially moving vortex to the lattice through the excitation of lattice vibrations and show that the efficiency of this process is higher for attractive than for repulsive nucleus–vortex interactions. We explore the unpinning of a vortex under the action of the applied Magnus force and find that it is influenced by multiple parameters, including the sign of the pinning force, the lattice orientation, composition, temperature, and the energy of the pinning to individual nuclei. In lattices with multiple grains, the unpinning transition is triggered inside the grains with weaker pinning, propagates along the vortex (mediated by the excited Kelvin waves), and crosses into grains with stronger pinning. This is likely to effectively decrease the critical force at which vortices unpin and to produce extended regions of unpinned vorticity. The shearing of the crust lattice (e.g., by a starquake) initiates the unpinning of the vortices that are crossing the slip plane. A close encounter of an unpinned vortex with a pinned vortex would cause the latter to unpin, perhaps initiating an unpinning avalanche of many vortices.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147519234","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}
Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4bde
Patrick M. Shober
Asteroid activity (e.g., thermo-mechanical breakdown, impacts, rotational shedding, tidal disruption) can inject meteoroids into near-Earth space and leave detectable signatures in orbit catalogs. We searched for such recent signatures using orbit-similarity statistics and explicit null-hypothesis testing applied to shower-removed, asteroidal video-meteor datasets. Our sample comprises 235,271 meteors and fireballs from four all-sky video networks (Global Meteor Network, GMN, Cameras for All-sky Meteor Surveillance, CAMS, European viDeo Meteor Observation Network Database, EDMOND, and SonotaCo). For meteors we use the geocentric dissimilarity criterion DN and construct kernel density estimator (KDE)-based sporadic null realizations to evaluate (i) global cumulative similarity distributions and (ii) localized DN-conditioned (DN < 0.015) pair-excess maps in the (U, λ⊙) plane; we additionally apply DBSCAN (ϵ = 0.03, ) to isolate the coherent, statistically significant structures. We find no survey-consistent, stream-like signature in the Earth-like, low-inclination region expected for a distinct recent tidal-disruption family; instead, significant-bin membership implies, under our adopted detection thresholds and binning, a conservative combined upper limit of ≤53/235,271 ( ≤2.3 × 10−4) for sporadic asteroidal meteors plausibly attributable to a detectable recent tidal-disruption-like contribution. In contrast, we confirm the detection of a new diffuse southern Virginid-region stream: GMN exhibits a local z-score of 6.32 relative to the KDE-null mean in the U − λ⊙ phase space (global significance of 5.3σ), with weaker supporting excess in SonotaCo and EDMOND. DBSCAN isolates N = 282 members (243 GMN plus additional SonotaCo, CAMS, and EDMOND) on a low-perihelion, asteroidal orbit (q = 0.22 ± 0.01 au, i = 12 3 ± 1 8, TJ = 4.6 ± 0.3) consistent with near-Sun thermo-mechanical “rock-comet” activity.
{"title":"Asteroidal Activity among Meteor Datasets: Confirmed New “Rock-comet” Stream and Search for a Tidal-disruption Signature","authors":"Patrick M. Shober","doi":"10.3847/1538-4357/ae4bde","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4bde","url":null,"abstract":"Asteroid activity (e.g., thermo-mechanical breakdown, impacts, rotational shedding, tidal disruption) can inject meteoroids into near-Earth space and leave detectable signatures in orbit catalogs. We searched for such recent signatures using orbit-similarity statistics and explicit null-hypothesis testing applied to shower-removed, asteroidal video-meteor datasets. Our sample comprises 235,271 meteors and fireballs from four all-sky video networks (Global Meteor Network, GMN, Cameras for All-sky Meteor Surveillance, CAMS, European viDeo Meteor Observation Network Database, EDMOND, and SonotaCo). For meteors we use the geocentric dissimilarity criterion DN and construct kernel density estimator (KDE)-based sporadic null realizations to evaluate (i) global cumulative similarity distributions and (ii) localized DN-conditioned (DN < 0.015) pair-excess maps in the (U, λ⊙) plane; we additionally apply DBSCAN (ϵ = 0.03, ) to isolate the coherent, statistically significant structures. We find no survey-consistent, stream-like signature in the Earth-like, low-inclination region expected for a distinct recent tidal-disruption family; instead, significant-bin membership implies, under our adopted detection thresholds and binning, a conservative combined upper limit of ≤53/235,271 ( ≤2.3 × 10−4) for sporadic asteroidal meteors plausibly attributable to a detectable recent tidal-disruption-like contribution. In contrast, we confirm the detection of a new diffuse southern Virginid-region stream: GMN exhibits a local z-score of 6.32 relative to the KDE-null mean in the U − λ⊙ phase space (global significance of 5.3σ), with weaker supporting excess in SonotaCo and EDMOND. DBSCAN isolates N = 282 members (243 GMN plus additional SonotaCo, CAMS, and EDMOND) on a low-perihelion, asteroidal orbit (q = 0.22 ± 0.01 au, i = 12 3 ± 1 8, TJ = 4.6 ± 0.3) consistent with near-Sun thermo-mechanical “rock-comet” activity.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147519271","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}
Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4a9e
Nari Suzuki, Shigeo Yamauchi, Kumiko K. Nobukawa, Rui Himono and Masayoshi Nobukawa
We have performed 1–12 keV spectral analyses of the recombining plasma associated with the supernova remnant (SNR) W49B using the Suzaku archive data. The analysis results for the whole SNR spectrum indicate that the recombination timescale varies within (5–7) × 1011 cm−3 s among elements from Mg to Fe and Ni of the RP or that the initial ionization temperatures of the elements vary between 1.6 and 2.7 keV. This paper reports on the results of a more detailed investigation using the latter approach, the multicomponent ionization temperature model. In the overall spectrum, the initial ionization temperatures is estimated to be 2 keV for the lighter elements (Mg, Si) and 5 keV for the heavier elements (Ar and Fe group). For electron cooling scenarios, plasma ionization must proceed at once during a period of high density within about 500 yr after the explosion. The initial ionization temperatures tend to be higher in the east, which would be due to difference of density in circumstellar medium in the early period. On the other hand, current ionization temperatures are found to be spatially uniform, which would be explained by the ionization enhancement scenario by low-energy cosmic rays.
{"title":"Spatial Variation of a Recombining Plasma in the Supernova Remnant W49B","authors":"Nari Suzuki, Shigeo Yamauchi, Kumiko K. Nobukawa, Rui Himono and Masayoshi Nobukawa","doi":"10.3847/1538-4357/ae4a9e","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a9e","url":null,"abstract":"We have performed 1–12 keV spectral analyses of the recombining plasma associated with the supernova remnant (SNR) W49B using the Suzaku archive data. The analysis results for the whole SNR spectrum indicate that the recombination timescale varies within (5–7) × 1011 cm−3 s among elements from Mg to Fe and Ni of the RP or that the initial ionization temperatures of the elements vary between 1.6 and 2.7 keV. This paper reports on the results of a more detailed investigation using the latter approach, the multicomponent ionization temperature model. In the overall spectrum, the initial ionization temperatures is estimated to be 2 keV for the lighter elements (Mg, Si) and 5 keV for the heavier elements (Ar and Fe group). For electron cooling scenarios, plasma ionization must proceed at once during a period of high density within about 500 yr after the explosion. The initial ionization temperatures tend to be higher in the east, which would be due to difference of density in circumstellar medium in the early period. On the other hand, current ionization temperatures are found to be spatially uniform, which would be explained by the ionization enhancement scenario by low-energy cosmic rays.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"92 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147519236","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}
Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4d0f
Wuming Yang, Shuya Dou, Xiangcun Meng, Yaqian Wu and Shaolan Bi
The observed lithium (Li) abundance of Galactic halo stars mainly falls within the range of 2.0–2.4 dex. This nearly constant value, known as the Spite plateau, is approximately a factor of 3 lower than the value predicted from cosmic microwave background measurements and standard Big Bang nucleosynthesis (BBN) calculations. This discrepancy—referred to as the cosmological Li problem—is considered a potential indication of new physics or astrophysical processes. We employed models incorporating gravitational settling, diffusion, rotation, and magnetic fields to explain the Spite plateau. The rotating models predict that Li abundances in stars with ages of roughly 8–13 Gyr and effective temperatures between 6400 and 5900 K generally fall within 2.0–2.4 dex, forming a well-defined Li plateau, followed by a sharp decline in Li abundance down to about 5200 K. The Li plateau results from the combined effects of variations in convection zone depth, gravitational settling, diffusion, rotation, and magnetic fields. For red giant branch stars with Teff ≲ 5200 K, the rotating models predict another Li plateau with an abundance of about 1.0 dex. These results are in good agreement with observations. Moreover, the initial Li abundance of 2.72 dex adopted in the models matches the BBN prediction, implying that the Li problem arises from stellar Li depletion. Furthermore, the rotating models also reproduce the Li and Be distributions of the sample that exhibit the Spite plateau meltdown and Be deviation.
{"title":"Using Lithium and Beryllium to Study the Structure and Evolution of Rotating Stars: The Spite Plateau of Halo Stars","authors":"Wuming Yang, Shuya Dou, Xiangcun Meng, Yaqian Wu and Shaolan Bi","doi":"10.3847/1538-4357/ae4d0f","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4d0f","url":null,"abstract":"The observed lithium (Li) abundance of Galactic halo stars mainly falls within the range of 2.0–2.4 dex. This nearly constant value, known as the Spite plateau, is approximately a factor of 3 lower than the value predicted from cosmic microwave background measurements and standard Big Bang nucleosynthesis (BBN) calculations. This discrepancy—referred to as the cosmological Li problem—is considered a potential indication of new physics or astrophysical processes. We employed models incorporating gravitational settling, diffusion, rotation, and magnetic fields to explain the Spite plateau. The rotating models predict that Li abundances in stars with ages of roughly 8–13 Gyr and effective temperatures between 6400 and 5900 K generally fall within 2.0–2.4 dex, forming a well-defined Li plateau, followed by a sharp decline in Li abundance down to about 5200 K. The Li plateau results from the combined effects of variations in convection zone depth, gravitational settling, diffusion, rotation, and magnetic fields. For red giant branch stars with Teff ≲ 5200 K, the rotating models predict another Li plateau with an abundance of about 1.0 dex. These results are in good agreement with observations. Moreover, the initial Li abundance of 2.72 dex adopted in the models matches the BBN prediction, implying that the Li problem arises from stellar Li depletion. Furthermore, the rotating models also reproduce the Li and Be distributions of the sample that exhibit the Spite plateau meltdown and Be deviation.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147519264","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}
Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4e29
Thomas Meier, Douglas Potter, Christian Reinhardt and Joachim Stadel
We present pkdgrav3, a high-performance, fully parallel tree smoothed particle hydrodynamics (SPH) code designed for large-scale hydrodynamic simulations including self-gravity. Building upon the long development history of pkdgrav, the code combines an efficient hierarchical tree algorithm for gravity and neighbor finding with a modern implementation of SPH optimized for massively parallel hybrid CPU/GPU architectures. Its hybrid shared/distributed memory model, combined with an asynchronous communication scheme, allows pkdgrav3 to scale efficiently to thousands of CPU cores and GPUs. We validate the numerical accuracy of pkdgrav3 using a suite of standard tests, demonstrating excellent agreement with analytic or reference solutions. The code was already used in several peer-reviewed publications to model planetary-scale impacts, where SPH’s Lagrangian nature allows for accurate tracking of material origin and thermodynamic evolution. These examples highlight pkdgrav3’s robustness and efficiency in simulating highly dynamical, self-gravitating systems. pkdgrav3 thus provides a powerful, flexible, and scalable platform for astrophysical and planetary applications, capable of exploiting the full potential of modern heterogeneous high-performance computing systems.
{"title":"Smoothed Particle Hydrodynamics in pkdgrav3 for Shock Physics Simulations. I. Hydrodynamics","authors":"Thomas Meier, Douglas Potter, Christian Reinhardt and Joachim Stadel","doi":"10.3847/1538-4357/ae4e29","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4e29","url":null,"abstract":"We present pkdgrav3, a high-performance, fully parallel tree smoothed particle hydrodynamics (SPH) code designed for large-scale hydrodynamic simulations including self-gravity. Building upon the long development history of pkdgrav, the code combines an efficient hierarchical tree algorithm for gravity and neighbor finding with a modern implementation of SPH optimized for massively parallel hybrid CPU/GPU architectures. Its hybrid shared/distributed memory model, combined with an asynchronous communication scheme, allows pkdgrav3 to scale efficiently to thousands of CPU cores and GPUs. We validate the numerical accuracy of pkdgrav3 using a suite of standard tests, demonstrating excellent agreement with analytic or reference solutions. The code was already used in several peer-reviewed publications to model planetary-scale impacts, where SPH’s Lagrangian nature allows for accurate tracking of material origin and thermodynamic evolution. These examples highlight pkdgrav3’s robustness and efficiency in simulating highly dynamical, self-gravitating systems. pkdgrav3 thus provides a powerful, flexible, and scalable platform for astrophysical and planetary applications, capable of exploiting the full potential of modern heterogeneous high-performance computing systems.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147519311","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}
Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4a1c
C. Q. Wang, Z. Wang, Z. X. Wen, W. D. Fu, W. Z. Zhang and B. L. Chen
Mirror-mode (MM) structures, characterized by intermittent sharp depressions or enhancements of magnetic magnitude, are key plasma-instability-driven phenomena and commonly observed in high-β and temperature-anisotropic space plasmas. Although MM structures have been well studied in Earth’s magnetosheath, their properties in Jupiter’s magnetosheath remain poorly understood due to the limited spatial and temporal coverage of previous missions. Here, by using Juno observations, we present the first comprehensive statistical analysis of MM structures in Jupiter’s magnetosheath. We investigate their spatial distribution and occurrence rate across a broad range of latitudes, thereby clarifying their global spatial characteristics. In addition, we examine the electron pitch-angle distributions associated with MM events to explore particle behavior and possible wave–particle interactions within these structures. These results advance our understanding of the formation and evolution of MM structures in giant planetary magnetosheaths and their related electron dynamics in Jupiter’s magnetosheath.
{"title":"Statistical Properties of Mirror-mode Structures in Jupiter’s Magnetosheath Based on Juno Observations","authors":"C. Q. Wang, Z. Wang, Z. X. Wen, W. D. Fu, W. Z. Zhang and B. L. Chen","doi":"10.3847/1538-4357/ae4a1c","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a1c","url":null,"abstract":"Mirror-mode (MM) structures, characterized by intermittent sharp depressions or enhancements of magnetic magnitude, are key plasma-instability-driven phenomena and commonly observed in high-β and temperature-anisotropic space plasmas. Although MM structures have been well studied in Earth’s magnetosheath, their properties in Jupiter’s magnetosheath remain poorly understood due to the limited spatial and temporal coverage of previous missions. Here, by using Juno observations, we present the first comprehensive statistical analysis of MM structures in Jupiter’s magnetosheath. We investigate their spatial distribution and occurrence rate across a broad range of latitudes, thereby clarifying their global spatial characteristics. In addition, we examine the electron pitch-angle distributions associated with MM events to explore particle behavior and possible wave–particle interactions within these structures. These results advance our understanding of the formation and evolution of MM structures in giant planetary magnetosheaths and their related electron dynamics in Jupiter’s magnetosheath.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147519233","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}
Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4fbc
Cong Wang, Qian Ye, Xuan Cheng and Fei He
Heavy ions upstream and downstream of interplanetary shocks are not only subject to acceleration, heating, and spatiotemporal modulation during their propagation in interplanetary space, but they can also, in turn, influence the dynamical properties of the shocks themselves. Using ACE/Solar Wind Ion Composition Spectrometer observations, we analyzed the heavy-ion characteristics associated with 163 interplanetary shocks and classified the shocks into four categories for separate examination. We find that most forward shocks are driven by ICMEs, and their occurrence exhibits an 11 yr modulation consistent with the solar cycle, whereas reverse shocks show no clear periodic behavior. Overall, both heavy-ion abundance ratios and average charge states are systematically higher in forward shocks than in reverse shocks. For forward shocks, weak and strong shocks exhibit broadly similar trends: the heavy-ion parameters remain relatively steady prior to shock arrival, followed by a pronounced enhancement immediately after the shock crossing. Events with larger Alfvén Mach numbers tend to show steeper and stronger increases. In contrast, both the heavy-ion abundance ratios and average charge states decrease to their minimum values before the arrival of reverse shocks and gradually recover afterward. This behavior suggests that reverse shocks reorganize the spatial distribution of heavy ions as they propagate through interplanetary space.
{"title":"Variations of Heavy Ions in Different Types of Interplanetary Shocks","authors":"Cong Wang, Qian Ye, Xuan Cheng and Fei He","doi":"10.3847/1538-4357/ae4fbc","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4fbc","url":null,"abstract":"Heavy ions upstream and downstream of interplanetary shocks are not only subject to acceleration, heating, and spatiotemporal modulation during their propagation in interplanetary space, but they can also, in turn, influence the dynamical properties of the shocks themselves. Using ACE/Solar Wind Ion Composition Spectrometer observations, we analyzed the heavy-ion characteristics associated with 163 interplanetary shocks and classified the shocks into four categories for separate examination. We find that most forward shocks are driven by ICMEs, and their occurrence exhibits an 11 yr modulation consistent with the solar cycle, whereas reverse shocks show no clear periodic behavior. Overall, both heavy-ion abundance ratios and average charge states are systematically higher in forward shocks than in reverse shocks. For forward shocks, weak and strong shocks exhibit broadly similar trends: the heavy-ion parameters remain relatively steady prior to shock arrival, followed by a pronounced enhancement immediately after the shock crossing. Events with larger Alfvén Mach numbers tend to show steeper and stronger increases. In contrast, both the heavy-ion abundance ratios and average charge states decrease to their minimum values before the arrival of reverse shocks and gradually recover afterward. This behavior suggests that reverse shocks reorganize the spatial distribution of heavy ions as they propagate through interplanetary space.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147519292","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}
Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4d11
Ronald L. Moore, Sanjiv K. Tiwari, V. Aparna, Navdeep K. Panesar and Alphonse C. Sterling
We explore what fraction of delta sunspots with a sharp polarity inversion line (PIL) in photospheric magnetograms are produced by a writhe kink in an emerging twisted flux rope. Using simultaneous full-disk magnetograms and continuum images from the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory, we identified 28 random sharp-PIL delta sunspots that form well on the disk. Only one of these formed from a single newly emerged bipolar magnetic region (BMR) and is therefore a candidate for being produced by a single emerging writhe-kinked flux rope. This outcome indicates that few, if any, sharp-PIL delta sunspots are produced by a single emerging writhe-kinked flux rope; this is the main new finding of this paper. The remaining 27 are produced by the merging of two or more emerging or emerged BMRs. We refer to delta-sunspot genesis from a single BMR as Type I genesis. Among the other 27 delta sunspots, we identify three additional genesis types: Type II, Type III, and Type IV. For each of the four genesis types we present an observed example and schematic drawings depicting our proposed formation scenario(s). The core idea of these scenarios is that delta sunspots form when opposite-polarity magnetic flux is packed together by advection into a convective downflow.
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Pub Date : 2026-03-27DOI: 10.3847/1538-4357/ae4ee2
M. A. Hidalgo
Magnetic clouds (MCs) are large-scale magnetic structures in the solar wind whose internal physical processes remain only partially understood. In this work, we present an extended analytical model of MCs that simultaneously describes the magnetic field, plasma pressure, current density, and induced electric field during the spacecraft crossing of the structure. Building upon previous non-force-free formulations, the model incorporates the induced electric field as an additional physical constraint linking magnetic and plasma dynamics. The model is applied to a set of representative MC events observed by the Wind spacecraft. By fitting multiple observables simultaneously, the approach reduces parameter correlations and leads to more stable determinations of the flux-rope axis orientation compared to earlier versions based solely on magnetic field measurements. The inclusion of plasma-related quantities allows departures from idealized force-free configurations to be identified and provides additional insight into the internal topology and evolution of MCs. The comparison of several example events illustrates both the capabilities and limitations of the model, showing that its performance degrades in cases exhibiting enhanced short-timescale variability or boundary interactions. Overall, the present formulation provides a more physically consistent framework for interpreting in situ observations of MCs in the interplanetary medium.
{"title":"A Global Magnetic Topology Model for Magnetic Clouds. V","authors":"M. A. Hidalgo","doi":"10.3847/1538-4357/ae4ee2","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4ee2","url":null,"abstract":"Magnetic clouds (MCs) are large-scale magnetic structures in the solar wind whose internal physical processes remain only partially understood. In this work, we present an extended analytical model of MCs that simultaneously describes the magnetic field, plasma pressure, current density, and induced electric field during the spacecraft crossing of the structure. Building upon previous non-force-free formulations, the model incorporates the induced electric field as an additional physical constraint linking magnetic and plasma dynamics. The model is applied to a set of representative MC events observed by the Wind spacecraft. By fitting multiple observables simultaneously, the approach reduces parameter correlations and leads to more stable determinations of the flux-rope axis orientation compared to earlier versions based solely on magnetic field measurements. The inclusion of plasma-related quantities allows departures from idealized force-free configurations to be identified and provides additional insight into the internal topology and evolution of MCs. The comparison of several example events illustrates both the capabilities and limitations of the model, showing that its performance degrades in cases exhibiting enhanced short-timescale variability or boundary interactions. Overall, the present formulation provides a more physically consistent framework for interpreting in situ observations of MCs in the interplanetary medium.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147519256","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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