Pub Date : 2024-08-09DOI: 10.3389/fspas.2024.1411810
Binyang Liu, I. Dell’Antonio, Nicolas Chotard, D. Clowe
Galaxy cluster lensing is a powerful tool for measuring the mass of galaxy clusters, but accurate shear measurement and calibration are critical to obtaining reliable results. This study focuses on the measurement and calibration of weak lensing shears to improve mass estimates in cluster lensing. To deal with the problem, we first developed an image simulation pipeline, jedisim, which utilizes galaxy images extracted from the Hubble Space Telescope (HST) Ultra Deep Field (UDF) and the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS).The simulations represent realistic galaxy distributions and morphologies as input sources. The foreground halo with a Navarro–Frenk–White (NFW) profile is constructed such that the lensing signals of background galaxies can be measured by the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) Science Pipelines. By comparing the measured reduced shear gmeas and the true reduced shear gtrue, we observe non-linearity up to g≲0.6. We fit polynomials to the data with quadratic correction adequate to g≲0.4. Meanwhile, we conduct mass estimates using the pzmassfitter code on four different clusters.The mass estimate results are significantly improved after applying the shear calibration derived from the present work—from 4.954±0.504×1014M⊙ to 10.507±0.498×1014M⊙ after calibration for a simulated cluster with the mass of 10×1014M⊙. In multiple cases of validation, the estimated results are all consistent with true cluster mass.This study yields the first relationship between reality and shape measurement of the LSST Science Pipelines and serves as the first step toward the overall goal of mass calibration in cluster lensing. By addressing the challenges in shear measurement and calibration, we aim to enhance the accuracy and reliability of mass estimates in galaxy cluster lensing studies.
{"title":"Measurement and calibration of non-linear shear terms in galaxy cluster fields","authors":"Binyang Liu, I. Dell’Antonio, Nicolas Chotard, D. Clowe","doi":"10.3389/fspas.2024.1411810","DOIUrl":"https://doi.org/10.3389/fspas.2024.1411810","url":null,"abstract":"Galaxy cluster lensing is a powerful tool for measuring the mass of galaxy clusters, but accurate shear measurement and calibration are critical to obtaining reliable results. This study focuses on the measurement and calibration of weak lensing shears to improve mass estimates in cluster lensing. To deal with the problem, we first developed an image simulation pipeline, jedisim, which utilizes galaxy images extracted from the Hubble Space Telescope (HST) Ultra Deep Field (UDF) and the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS).The simulations represent realistic galaxy distributions and morphologies as input sources. The foreground halo with a Navarro–Frenk–White (NFW) profile is constructed such that the lensing signals of background galaxies can be measured by the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) Science Pipelines. By comparing the measured reduced shear gmeas and the true reduced shear gtrue, we observe non-linearity up to g≲0.6. We fit polynomials to the data with quadratic correction adequate to g≲0.4. Meanwhile, we conduct mass estimates using the pzmassfitter code on four different clusters.The mass estimate results are significantly improved after applying the shear calibration derived from the present work—from 4.954±0.504×1014M⊙ to 10.507±0.498×1014M⊙ after calibration for a simulated cluster with the mass of 10×1014M⊙. In multiple cases of validation, the estimated results are all consistent with true cluster mass.This study yields the first relationship between reality and shape measurement of the LSST Science Pipelines and serves as the first step toward the overall goal of mass calibration in cluster lensing. By addressing the challenges in shear measurement and calibration, we aim to enhance the accuracy and reliability of mass estimates in galaxy cluster lensing studies.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141924029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-09DOI: 10.3389/fspas.2024.1425500
M. Liemohn
To mitigate the issues of inequity, exclusion, and a lack of diversity in the solar and space physics research community, a Research Topic collection gathered articles of how scientists in this discipline are taking strides to make this community more welcoming. This review summarizes the key advice from those articles and offers practical actions for both immediate and long-term implementation. There are six major topical categories into which the collection’s article can be grouped: early-year improvements (pre-college and undergraduate); inclusive project teams; diversity in awards; equity in hiring and promotion; leadership development; and the workplace environment. The scope of suggestions ranges from the very localized, such as the language choices we make in everyday conversations, to the institutional, such as the establishment of codes of conduct with a definition and enforcement of consequences for inappropriate behavior regarding inclusion and equity issues. It is hoped that the recommendations are applicable not only to the space physics community but also to others.
{"title":"Practical actions towards equity in space physics","authors":"M. Liemohn","doi":"10.3389/fspas.2024.1425500","DOIUrl":"https://doi.org/10.3389/fspas.2024.1425500","url":null,"abstract":"To mitigate the issues of inequity, exclusion, and a lack of diversity in the solar and space physics research community, a Research Topic collection gathered articles of how scientists in this discipline are taking strides to make this community more welcoming. This review summarizes the key advice from those articles and offers practical actions for both immediate and long-term implementation. There are six major topical categories into which the collection’s article can be grouped: early-year improvements (pre-college and undergraduate); inclusive project teams; diversity in awards; equity in hiring and promotion; leadership development; and the workplace environment. The scope of suggestions ranges from the very localized, such as the language choices we make in everyday conversations, to the institutional, such as the establishment of codes of conduct with a definition and enforcement of consequences for inappropriate behavior regarding inclusion and equity issues. It is hoped that the recommendations are applicable not only to the space physics community but also to others.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141924646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-26DOI: 10.3389/fspas.2024.1427260
David Avnir
A positive correlation was observed between the enantiomeric excess (ee) of L-isovaline (L-iVal) and the degree of aqueous alteration (AqA) of carbonaceous meteorites. The origin of this remarkable phenomenon has remained enigmatic from two points of view: First, the correlation is between seemingly unrelated observables–nothing about AqA is of chiral characteristics; and second, following the accepted assumption that circularly polarized light (CPL) was the origin of the observed meteoritic ee of L-amino acids (AAs), it remined unclear why some of the observed levels of the ee of L-iVal in that correlation are significantly higher than those observed in laboratory simulations or those obtained from circular dichroism (CD) g-factor calculations. The current proposition accounting for this picture attributes late AqA conditions of the meteoritic parent bodies as providing the grounds for amplification of early initially CPL-generated low levels of L-ee. For reasons summarized below, this interpretation, which treats the CPL event and the AqA process as occurring in wide-time separated eras, is re-visited. An alternative interpretation of the observed correlation and of the high ee-values, is provided. It focuses on hydrophilic dust-aggregates clouds in wet star-forming regions in early pre-solar times, where both the CPL event and the grounds leading to the later AqA processes of the parent bodies, occurred. This mechanism removes the time separation between the initial ee formation and the AqA of the parent body, and replaces it with parallel processes, providing a scenario to the observation of high ee’s without total destruction, and to the apparent AqA/L-ee correlation. Although iVal is at the focus of this report, the steps of the development of the alternative mechanism and the conclusions that arise from it, are relevant and applicable to the general observations of L-ee’s of meteoritic AA’s.
{"title":"On the correlation between the enantiomeric excess of L-isovaline and the level of aqueous alteration in carbonaceous meteorites","authors":"David Avnir","doi":"10.3389/fspas.2024.1427260","DOIUrl":"https://doi.org/10.3389/fspas.2024.1427260","url":null,"abstract":"A positive correlation was observed between the enantiomeric excess (ee) of L-isovaline (L-iVal) and the degree of aqueous alteration (AqA) of carbonaceous meteorites. The origin of this remarkable phenomenon has remained enigmatic from two points of view: First, the correlation is between seemingly unrelated observables–nothing about AqA is of chiral characteristics; and second, following the accepted assumption that circularly polarized light (CPL) was the origin of the observed meteoritic ee of L-amino acids (AAs), it remined unclear why some of the observed levels of the ee of L-iVal in that correlation are significantly higher than those observed in laboratory simulations or those obtained from circular dichroism (CD) g-factor calculations. The current proposition accounting for this picture attributes late AqA conditions of the meteoritic parent bodies as providing the grounds for amplification of early initially CPL-generated low levels of L-ee. For reasons summarized below, this interpretation, which treats the CPL event and the AqA process as occurring in wide-time separated eras, is re-visited. An alternative interpretation of the observed correlation and of the high ee-values, is provided. It focuses on hydrophilic dust-aggregates clouds in wet star-forming regions in early pre-solar times, where both the CPL event and the grounds leading to the later AqA processes of the parent bodies, occurred. This mechanism removes the time separation between the initial ee formation and the AqA of the parent body, and replaces it with parallel processes, providing a scenario to the observation of high ee’s without total destruction, and to the apparent AqA/L-ee correlation. Although iVal is at the focus of this report, the steps of the development of the alternative mechanism and the conclusions that arise from it, are relevant and applicable to the general observations of L-ee’s of meteoritic AA’s.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141800216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-25DOI: 10.3389/fspas.2024.1462935
James Wurster, P. Hennebelle, Kengo Tomida, Anna Rosen
{"title":"Editorial: Star formation: numerical simulations and what they teach us","authors":"James Wurster, P. Hennebelle, Kengo Tomida, Anna Rosen","doi":"10.3389/fspas.2024.1462935","DOIUrl":"https://doi.org/10.3389/fspas.2024.1462935","url":null,"abstract":"","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141805356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-23DOI: 10.3389/fspas.2024.1422164
E. P. Macho, W. Bristow, B. Gallardo-Lacourt, S. G. Shepherd, J. M. Ruohoniemi, E. Correia
The phenomenon known as strong thermal emission velocity enhancement (STEVE) is a narrow optical structure that may extend longitudinally for thousands of kilometers. Initially observed by amateur photographers, it has recently garnered researchers’ attention. STEVE has been associated with a rapid westward flow of ions in the ionosphere, known as subauroral ion drift (SAID). In this work, we investigate three occurrences of STEVE, using data from one of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) ground-based all-sky imagers (ASIs) located at Pinawa, Manitoba, and from the Super Dual Auroral Radar Network (SuperDARN). This approach allows us to verify the correlation between STEVE and SAID, as well as analyze the temporal variation of SAID observed during STEVE events. Our results suggest that the SAID activity starts before the STEVE, and the magnitude of the westward flow decreases as the STEVE progresses toward the end of its optical manifestation.
强热发射速度增强（STEVE）现象是一种狭长的光学结构，可纵向延伸数千公里。最初是由业余摄影爱好者观测到的，最近引起了研究人员的注意。STEVE 与电离层中快速向西流动的离子有关，被称为亚金牛座离子漂移（SAID）。在这项研究中，我们利用位于马尼托巴省皮纳瓦的一个地基全天空成像仪（ASI）和超级双极光雷达网（SuperDARN）提供的数据，对三次 STEVE 事件进行了研究。这种方法使我们能够验证 STEVE 和 SAID 之间的相关性，并分析在 STEVE 事件期间观测到的 SAID 的时间变化。我们的研究结果表明，SAID活动在STEVE之前就开始了，而且随着STEVE向其光学表现的末期发展，西向气流的幅度会减小。
{"title":"Exploring the relationship between STEVE and SAID during three events observed by SuperDARN","authors":"E. P. Macho, W. Bristow, B. Gallardo-Lacourt, S. G. Shepherd, J. M. Ruohoniemi, E. Correia","doi":"10.3389/fspas.2024.1422164","DOIUrl":"https://doi.org/10.3389/fspas.2024.1422164","url":null,"abstract":"The phenomenon known as strong thermal emission velocity enhancement (STEVE) is a narrow optical structure that may extend longitudinally for thousands of kilometers. Initially observed by amateur photographers, it has recently garnered researchers’ attention. STEVE has been associated with a rapid westward flow of ions in the ionosphere, known as subauroral ion drift (SAID). In this work, we investigate three occurrences of STEVE, using data from one of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) ground-based all-sky imagers (ASIs) located at Pinawa, Manitoba, and from the Super Dual Auroral Radar Network (SuperDARN). This approach allows us to verify the correlation between STEVE and SAID, as well as analyze the temporal variation of SAID observed during STEVE events. Our results suggest that the SAID activity starts before the STEVE, and the magnitude of the westward flow decreases as the STEVE progresses toward the end of its optical manifestation.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141813530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.3389/fspas.2024.1401846
Jiong Qiu
The explosive release of energy in the solar atmosphere is driven magnetically, but the mechanisms that trigger the onset of the eruption remain controversial. In the case of flares and coronal mass ejections (CMEs), ideal or non-ideal instabilities usually occur in the corona, but it is difficult to obtain direct observations and diagnostics there. To overcome this difficulty, we analyze observational signatures in the upper chromosphere or transition region, particularly brightening and dimming at the base of coronal magnetic structures. In this paper, we examine the time evolution of spatially resolved light curves in two eruptive flares and identify a variety of tempo-spatial sequences of brightening and dimming, such as dimming followed by brightening and dimming preceded by brightening. These brightening–dimming sequences are indicative of the configuration of energy release in the form of plasma heating or bulk motion. We demonstrate the potential of using these analyses to diagnose the properties of magnetic reconnection and plasma expansion in the corona during the early stages of the eruption.
{"title":"Tracing field lines that are reconnecting, or expanding, or both","authors":"Jiong Qiu","doi":"10.3389/fspas.2024.1401846","DOIUrl":"https://doi.org/10.3389/fspas.2024.1401846","url":null,"abstract":"The explosive release of energy in the solar atmosphere is driven magnetically, but the mechanisms that trigger the onset of the eruption remain controversial. In the case of flares and coronal mass ejections (CMEs), ideal or non-ideal instabilities usually occur in the corona, but it is difficult to obtain direct observations and diagnostics there. To overcome this difficulty, we analyze observational signatures in the upper chromosphere or transition region, particularly brightening and dimming at the base of coronal magnetic structures. In this paper, we examine the time evolution of spatially resolved light curves in two eruptive flares and identify a variety of tempo-spatial sequences of brightening and dimming, such as dimming followed by brightening and dimming preceded by brightening. These brightening–dimming sequences are indicative of the configuration of energy release in the form of plasma heating or bulk motion. We demonstrate the potential of using these analyses to diagnose the properties of magnetic reconnection and plasma expansion in the corona during the early stages of the eruption.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141814888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-19DOI: 10.3389/fspas.2024.1309136
M. Ivarsen, J.‐P St-Maurice, Yaqi Jin, Jaeheung Park, Lisa Buschmann, Lasse B. N. Clausen
Using two separate databases of in situ ionospheric observations, we present case studies and perform a statistical investigation of the link between energetic precipitating particles during the polar night and high-latitude F-region steepening density spectra. Our study covers approximately 3 years of data obtained near the peak of the 24th solar cycle from four Defense Meteorological Satellite Program satellites and from the European Space Agency’s Swarm satellites. Focusing on the midnight sector of the auroral oval, we found that there is a near-perfect co-location between high-energy precipitating particles and occurrence of dissipating F-region plasma density spectra. This is because the precipitating energy flux strongly enhances the E-region Pedersen conductivity, allowing fast and efficient dissipation of kilometer-scale F-region irregularities. Spectra that are possibly non-dissipating are in turn co-located with the distribution of soft electron precipitation. Together, dissipating and non-dissipating density spectra constitute two distinct irregularity regimes. Surprisingly, we also found that efficient dissipation notwithstanding, high-energy precipitating particles cause a net increase in the F-region irregularity power, suggesting that growth and dissipation are interlinked and that some of the observed F-region irregularities may conceivably be generated in the E region. This work is expected to be beneficial for the classification of F-region in situ density spectra and suggests that such density spectra can be used to infer the presence of high-energy or low-energy precipitations based on spectral properties.
我们利用两个独立的电离层现场观测数据库，对极夜期间的高能降水粒子与高纬度 F 区陡峭密度谱之间的联系进行了案例研究和统计调查。我们的研究涵盖了从四颗国防气象卫星计划卫星和欧洲空间局的 Swarm 卫星获得的接近第 24 个太阳周期峰值的约 3 年数据。我们重点研究了极光椭圆的午夜部分，发现高能降水粒子与发生消散的F区等离子体密度谱之间存在近乎完美的共定位。这是因为析出的能量通量极大地增强了 E 区域的 Pedersen 传导性，使千米尺度的 F 区域不规则现象得以快速有效地消散。可能是非耗散的频谱反过来又与软电子析出的分布共同定位。消散密度谱和非消散密度谱共同构成了两种不同的不规则状态。令人惊讶的是，我们还发现，尽管存在有效的耗散，高能析出粒子仍会导致 F 区不规则度功率的净增加，这表明生长和耗散是相互关联的，可以想象观测到的一些 F 区不规则度可能是在 E 区产生的。这项工作预计将有助于对 F 区域的原位密度谱进行分类，并表明可以根据这些密度谱的光谱特性来推断是否存在高能或低能沉淀。
{"title":"To what degree does a high-energy aurora destroy F-region irregularities?","authors":"M. Ivarsen, J.‐P St-Maurice, Yaqi Jin, Jaeheung Park, Lisa Buschmann, Lasse B. N. Clausen","doi":"10.3389/fspas.2024.1309136","DOIUrl":"https://doi.org/10.3389/fspas.2024.1309136","url":null,"abstract":"Using two separate databases of in situ ionospheric observations, we present case studies and perform a statistical investigation of the link between energetic precipitating particles during the polar night and high-latitude F-region steepening density spectra. Our study covers approximately 3 years of data obtained near the peak of the 24th solar cycle from four Defense Meteorological Satellite Program satellites and from the European Space Agency’s Swarm satellites. Focusing on the midnight sector of the auroral oval, we found that there is a near-perfect co-location between high-energy precipitating particles and occurrence of dissipating F-region plasma density spectra. This is because the precipitating energy flux strongly enhances the E-region Pedersen conductivity, allowing fast and efficient dissipation of kilometer-scale F-region irregularities. Spectra that are possibly non-dissipating are in turn co-located with the distribution of soft electron precipitation. Together, dissipating and non-dissipating density spectra constitute two distinct irregularity regimes. Surprisingly, we also found that efficient dissipation notwithstanding, high-energy precipitating particles cause a net increase in the F-region irregularity power, suggesting that growth and dissipation are interlinked and that some of the observed F-region irregularities may conceivably be generated in the E region. This work is expected to be beneficial for the classification of F-region in situ density spectra and suggests that such density spectra can be used to infer the presence of high-energy or low-energy precipitations based on spectral properties.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141821580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-18DOI: 10.3389/fspas.2024.1425165
Z. Kaymaz, Zdenek Nemecek, N. Tsyganenko, V. S. Semenov, N. Erkaev, N. T. Gubaidulin
Based on a new mathematical framework and large multi-year multi-mission data sets, we reconstruct electric currents and magnetic fields around the dayside magnetopause and their dependence on the incoming solar wind, IMF, and geodipole tilt. The model architecture builds on previously developed mathematical frameworks and includes two separate blocks: for the magnetosheath and for the adjacent outer magnetosphere. Accordingly, the model is developed in two stages: 1) reconstruction of a best-fit magnetopause and underlying dayside magnetosphere, based on a simple shielded configuration, and 2) derivation of the magnetosheath magnetic field, represented by a sum of toroidal and poloidal terms, each expanded into spherical harmonic series of angular coordinates and powers of normal distance from the boundary. The spacecraft database covers the period from 1995 through 2022 and is composed of data from Geotail, Cluster, Themis, and MMS, with the total number of 1-min averages about 3 M. The modeling reveals orderly patterns of the IMF draping around the magnetosphere and of the magnetopause currents, controlled by the IMF orientation, solar wind pressure, and the Earth’s dipole tilt. The obtained results are discussed in terms of the magnetosheath flux pile-up and the dayside magnetosphere erosion during periods of northward or southward IMF, respectively.
基于一个新的数学框架和大型多年多任务数据集，我们重建了日侧磁层顶周围的电流和磁场及其与太阳风、IMF 和地球极倾斜的关系。模型结构建立在以前开发的数学框架基础上，包括两个独立的模块：磁鞘和邻近的外磁层。因此，模型的开发分为两个阶段：1）根据简单的屏蔽配置，重建最合适的磁层顶和下层日侧磁层；2）推导磁鞘磁场，由环向和极向项的总和表示，每个项都扩展为角坐标的球谐波序列和边界法向距离的幂。航天器数据库涵盖 1995 年至 2022 年期间的数据，由 Geotail、Cluster、Themis 和 MMS 的数据组成，1 分钟平均数据总数约为 300 万条。建模揭示了磁层周围的 IMF 垂褶和磁极电流的有序模式，这些模式受 IMF 方向、太阳风压力和地球偶极倾斜的控制。所获得的结果分别从磁鞘通量堆积和在 IMF 向北或向南期间日侧磁层侵蚀的角度进行了讨论。
{"title":"Magnetic fields and electric currents around the dayside magnetopause as inferred from data-constrained modeling","authors":"Z. Kaymaz, Zdenek Nemecek, N. Tsyganenko, V. S. Semenov, N. Erkaev, N. T. Gubaidulin","doi":"10.3389/fspas.2024.1425165","DOIUrl":"https://doi.org/10.3389/fspas.2024.1425165","url":null,"abstract":"Based on a new mathematical framework and large multi-year multi-mission data sets, we reconstruct electric currents and magnetic fields around the dayside magnetopause and their dependence on the incoming solar wind, IMF, and geodipole tilt. The model architecture builds on previously developed mathematical frameworks and includes two separate blocks: for the magnetosheath and for the adjacent outer magnetosphere. Accordingly, the model is developed in two stages: 1) reconstruction of a best-fit magnetopause and underlying dayside magnetosphere, based on a simple shielded configuration, and 2) derivation of the magnetosheath magnetic field, represented by a sum of toroidal and poloidal terms, each expanded into spherical harmonic series of angular coordinates and powers of normal distance from the boundary. The spacecraft database covers the period from 1995 through 2022 and is composed of data from Geotail, Cluster, Themis, and MMS, with the total number of 1-min averages about 3 M. The modeling reveals orderly patterns of the IMF draping around the magnetosphere and of the magnetopause currents, controlled by the IMF orientation, solar wind pressure, and the Earth’s dipole tilt. The obtained results are discussed in terms of the magnetosheath flux pile-up and the dayside magnetosphere erosion during periods of northward or southward IMF, respectively.","PeriodicalId":46793,"journal":{"name":"Frontiers in Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141825088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.3389/fspas.2024.1431804
Joseph E. Borovsky
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Pub Date : 2024-06-13DOI: 10.3389/fspas.2024.1401078
G. Pi, Z. Němeček, J. Šafránková, K. Grygorov
Modification of the solar wind parameters at the bow shock (BS) and through the magnetosheath (MSH) is essential for the solar wind–magnetosphere interaction chain. The present study uses two approaches to determine the spatial profile of magnetic field strength and plasma parameters and their fluctuations along the Sun-Earth line under different interplanetary magnetic field (IMF) orientations with an emphasis on radial IMF conditions. The first method is based on the superposed epoch analysis of all the complete THEMIS MSH crossings between 2007 and 2010. The second approach uses the distance of the observing spacecraft from the model magnetopause (MP) expressed in units of an MSH thickness for all THEMIS observations. The results of both these analyses are consistent, and their comparison with simulations reveals the following features: 1) the sign of the IMF north-south component has a negligible effect on the spatial profile of the magnetic field strength or plasma parameters as well as on the level of fluctuations; 2) the ion temperature is enhanced for a radial MF and it is nearly isotropic throughout MSH; 3) the fluctuation level of plasma parameters just downstream BS is enhanced under a radial IMF, but it gradually decreases toward MP to a value typical for other IMF orientations; 4) magnetic field fluctuations are enhanced by a factor of 1.7 in the whole magnetosheath when IMF points radially.
在弓形冲击（BS）处和通过磁鞘（MSH）时太阳风参数的变化对太阳风-磁层相互作用链至关重要。本研究采用两种方法来确定不同行星际磁场（IMF）方向下磁场强度和等离子体参数的空间剖面及其沿日地线的波动，重点是径向 IMF 条件。第一种方法是基于对 2007 年至 2010 年间所有完整的 THEMIS MSH 穿越的叠加纪元分析。第二种方法使用观测航天器与模型磁层顶（MP）的距离，以所有 THEMIS 观测的 MSH 厚度单位表示。这两种分析的结果是一致的，它们与模拟结果的比较揭示了以下特征：1）IMF 南北分量的符号对磁场强度或等离子体参数的空间剖面以及波动水平的影响微乎其微；2）径向 MF 会增强离子温度，而且在整个 MSH 几乎是各向同性的；3）在径向 IMF 下，BS 正下方等离子体参数的波动水平会增强，但向 MP 方向会逐渐减小到其他 IMF 方向的典型值；4）磁场波动在整个磁鞘中会增强 1.7 倍。
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