Pub Date : 2024-03-19DOI: 10.1088/1674-4527/ad2ac2
Zan Wang, De-Qing Kong, Hong-Bo Zhang, Yan Su, Xin-Ying Zhu, Cong-Si Wang, Yu-Chen Liu
To solve the problem of time-consuming measurement and correction of large antennas’ reflector deformation, a new microwave holography methodology based on a Phased Array Feed (PAF) is proposed. Starting from the known expression of receiving signals in microwave holography, the theory of PAF holography is derived through Geometrical Optics. Reflector deformation, as well as pointing deviation and subreflector offset, can be calculated out by applying the derived equations. A measurement and correction system based on PAF holography is depicted, and two kinds of measurement methods are illustrated. The proposed measurement methodology is verified by numerical simulation, and its measurement error is analyzed. The results indicate that our proposed methodology is feasible, especially for Cassegrain antennas.
{"title":"Reflector Deformation Measurement and Correction Methodology of Large Antenna Based on Phased Array Feed","authors":"Zan Wang, De-Qing Kong, Hong-Bo Zhang, Yan Su, Xin-Ying Zhu, Cong-Si Wang, Yu-Chen Liu","doi":"10.1088/1674-4527/ad2ac2","DOIUrl":"https://doi.org/10.1088/1674-4527/ad2ac2","url":null,"abstract":"To solve the problem of time-consuming measurement and correction of large antennas’ reflector deformation, a new microwave holography methodology based on a Phased Array Feed (PAF) is proposed. Starting from the known expression of receiving signals in microwave holography, the theory of PAF holography is derived through Geometrical Optics. Reflector deformation, as well as pointing deviation and subreflector offset, can be calculated out by applying the derived equations. A measurement and correction system based on PAF holography is depicted, and two kinds of measurement methods are illustrated. The proposed measurement methodology is verified by numerical simulation, and its measurement error is analyzed. The results indicate that our proposed methodology is feasible, especially for Cassegrain antennas.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"29 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-03-19DOI: 10.1088/1674-4527/ad2cd3
Jun-Chao Wang, Zhi-Qi Huang, Lu Huang, Jianqi Liu
We develop a Python tool to estimate the tail distribution of the number of dark matter halos beyond a mass threshold and in a given volume in a light-cone. The code is based on the extended Press–Schechter model and is computationally efficient, typically taking a few seconds on a personal laptop for a given set of cosmological parameters. The high efficiency of the code allows a quick estimation of the tension between cosmological models and the red candidate massive galaxies released by the James Webb Space Telescope, as well as scanning the theory space with the Markov Chain Monte Carlo method. As an example application, we use the tool to study the cosmological implication of the candidate galaxies presented in Labbé et al. The standard Λ cold dark matter (ΛCDM) model is well consistent with the data if the star formation efficiency can reach ∼0.3 at high redshift. For a low star formation efficiency ϵ ∼ 0.1, the ΛCDM model is disfavored at ∼2σ–3σ confidence level.
{"title":"Quantifying the Tension between Cosmological Models and JWST Red Candidate Massive Galaxies","authors":"Jun-Chao Wang, Zhi-Qi Huang, Lu Huang, Jianqi Liu","doi":"10.1088/1674-4527/ad2cd3","DOIUrl":"https://doi.org/10.1088/1674-4527/ad2cd3","url":null,"abstract":"We develop a Python tool to estimate the tail distribution of the number of dark matter halos beyond a mass threshold and in a given volume in a light-cone. The code is based on the extended Press–Schechter model and is computationally efficient, typically taking a few seconds on a personal laptop for a given set of cosmological parameters. The high efficiency of the code allows a quick estimation of the tension between cosmological models and the red candidate massive galaxies released by the James Webb Space Telescope, as well as scanning the theory space with the Markov Chain Monte Carlo method. As an example application, we use the tool to study the cosmological implication of the candidate galaxies presented in Labbé et al. The standard Λ cold dark matter (ΛCDM) model is well consistent with the data if the star formation efficiency can reach ∼0.3 at high redshift. For a low star formation efficiency <italic toggle=\"yes\">ϵ</italic> ∼ 0.1, the ΛCDM model is disfavored at ∼2<italic toggle=\"yes\">σ</italic>–3<italic toggle=\"yes\">σ</italic> confidence level.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"57 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-03-18DOI: 10.1088/1674-4527/ad2c3f
Jian-Qi Liu, Zhi-Qi Huang, Yan Su
The overabundance of the red and massive candidate galaxies observed by the James Webb Space Telescope (JWST) implies efficient structure formation or large star formation efficiency at high redshift z ∼ 10. In the scenario of a low or moderate star formation efficiency, because massive neutrinos tend to suppress the growth of structure of the universe, the JWST observation tightens the upper bound of the neutrino masses. Assuming Λ cold dark matter cosmology and a star formation efficiency ∈[0.05, 0.3] (flat prior), we perform joint analyses of Planck+JWST and Planck+BAO+JWST, and obtain improved constraints ∑mν < 0.196 eV and ∑mν < 0.111 eV at 95% confidence level, respectively. Based on the above assumptions, the inverted mass ordering, which implies ∑mν ≥ 0.1eV, is excluded by Planck+BAO+JWST at 92.7% confidence level.
{"title":"Cosmological Constraints on Neutrino Masses in Light of JWST Red and Massive Candidate Galaxies","authors":"Jian-Qi Liu, Zhi-Qi Huang, Yan Su","doi":"10.1088/1674-4527/ad2c3f","DOIUrl":"https://doi.org/10.1088/1674-4527/ad2c3f","url":null,"abstract":"The overabundance of the red and massive candidate galaxies observed by the James Webb Space Telescope (JWST) implies efficient structure formation or large star formation efficiency at high redshift <italic toggle=\"yes\">z</italic> ∼ 10. In the scenario of a low or moderate star formation efficiency, because massive neutrinos tend to suppress the growth of structure of the universe, the JWST observation tightens the upper bound of the neutrino masses. Assuming Λ cold dark matter cosmology and a star formation efficiency ∈[0.05, 0.3] (flat prior), we perform joint analyses of Planck+JWST and Planck+BAO+JWST, and obtain improved constraints ∑<italic toggle=\"yes\">m</italic>\u0000<sub>\u0000<italic toggle=\"yes\">ν</italic>\u0000</sub> < 0.196 eV and ∑<italic toggle=\"yes\">m</italic>\u0000<sub>\u0000<italic toggle=\"yes\">ν</italic>\u0000</sub> < 0.111 eV at 95% confidence level, respectively. Based on the above assumptions, the inverted mass ordering, which implies ∑<italic toggle=\"yes\">m</italic>\u0000<sub>\u0000<italic toggle=\"yes\">ν</italic>\u0000</sub> ≥ 0.1eV, is excluded by Planck+BAO+JWST at 92.7% confidence level.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"33 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-03-05DOI: 10.1088/1674-4527/ad18a4
Pham T. Nhung, Do T. Hoai, Pierre Darriulat, Pham Tuan-Anh, Pham N. Diep, Nguyen B. Ngoc, Tran T. Thai
New analyses of earlier ALMA observations of oxygen-rich AGB star EP Aquarii are presented, which complete a previously published analysis and offer a different interpretation of the morpho-kinematics of the circumstellar envelope. The birth of the equatorial density enhancement (EDE) is shown to occur very close to the star where evidence for rotation has been obtained. Close to the star and where outflows have been observed: their interaction with the gas of the nascent EDE is seen to play an important role in the development of the wind and the evolution of its radial velocity from 8 to 10 km s−1 on the polar symmetry axis to ∼2 km s−1 at the equator. It implies complex morpho-kinematics: making reliable interpretations with reasonable confidence is difficult. In particular, it questions an earlier interpretation implying the presence of a white dwarf companion orbiting the star at an angular distance of ∼0.″4 from its center. It proposes instead an interpretation in terms of a standard mass ejection associated with a shock wave leaving a void of emission in its wake. High Doppler velocity wings are seen to consist of two components, the upper velocity end of the global wind, reaching above ±12 km s−1, and an effective line broadening, confined within 200 mas from the center of the star, reaching above ±20 km s−1 and interpreted as caused by the pattern of shock waves resulting from the interaction between stellar pulsation and convective cell partition.
本文介绍了对富氧 AGB 星 EP Aquarii 早期 ALMA 观测结果的新分析，这些分析完成了之前发表的分析，并对星周外包层的形态运动学提供了不同的解释。研究表明，赤道密度增强（EDE）的产生非常靠近恒星，在恒星附近已经获得了旋转的证据。在恒星附近和观测到外流的地方：它们与新生 EDE 气体的相互作用被认为在风的发展及其径向速度从极对称轴上的 8 到 10 km s-1 演变到赤道上的∼2 km s-1 的过程中发挥了重要作用。这意味着复杂的形态运动学：很难做出具有合理可信度的可靠解释。特别是，它对早先的一种解释提出了质疑，这种解释意味着存在一个白矮星伴星，它围绕恒星运行，与恒星中心的角距离为∼0.″4。它提出的解释是，标准的质量抛射与冲击波有关，在其后留下了发射空隙。高多普勒速度翼由两部分组成，一部分是全球风的上端速度，达到±12 km s-1以上；另一部分是有效的线增宽，局限在恒星中心200mas的范围内，达到±20 km s-1以上，被解释为由恒星脉动和对流单元分区相互作用产生的冲击波模式引起的。
{"title":"EP Aquarii: A New Picture of the Circumstellar Envelope","authors":"Pham T. Nhung, Do T. Hoai, Pierre Darriulat, Pham Tuan-Anh, Pham N. Diep, Nguyen B. Ngoc, Tran T. Thai","doi":"10.1088/1674-4527/ad18a4","DOIUrl":"https://doi.org/10.1088/1674-4527/ad18a4","url":null,"abstract":"New analyses of earlier ALMA observations of oxygen-rich AGB star EP Aquarii are presented, which complete a previously published analysis and offer a different interpretation of the morpho-kinematics of the circumstellar envelope. The birth of the equatorial density enhancement (EDE) is shown to occur very close to the star where evidence for rotation has been obtained. Close to the star and where outflows have been observed: their interaction with the gas of the nascent EDE is seen to play an important role in the development of the wind and the evolution of its radial velocity from 8 to 10 km s<sup>−1</sup> on the polar symmetry axis to ∼2 km s<sup>−1</sup> at the equator. It implies complex morpho-kinematics: making reliable interpretations with reasonable confidence is difficult. In particular, it questions an earlier interpretation implying the presence of a white dwarf companion orbiting the star at an angular distance of ∼0.″4 from its center. It proposes instead an interpretation in terms of a standard mass ejection associated with a shock wave leaving a void of emission in its wake. High Doppler velocity wings are seen to consist of two components, the upper velocity end of the global wind, reaching above ±12 km s<sup>−1</sup>, and an effective line broadening, confined within 200 mas from the center of the star, reaching above ±20 km s<sup>−1</sup> and interpreted as caused by the pattern of shock waves resulting from the interaction between stellar pulsation and convective cell partition.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"33 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Ground-based arrays of imaging atmospheric Cherenkov telescopes (IACTs) are the most sensitive γ-ray detectors for energies of approximately 100 GeV and above. One such IACT is the High Altitude Detection of Astronomical Radiation (HADAR) experiment, which uses a large aperture refractive water lens system to capture atmospheric Cherenkov photons (i.e., the imaging atmospheric Cherenkov technique). The telescope array has a low threshold energy and large field of view, and can continuously scan the area of the sky being observed, which is conducive to monitoring and promptly responding to transient phenomena. The process of γ-hadron separation is essential in very-high-energy (>30 GeV) γ-ray astronomy and is a key factor for the successful utilization of IACTs. In this study, Monte Carlo simulations were carried out to model the response of cosmic rays within the HADAR detectors. By analyzing the Hillas parameters and the distance between the event core and the telescope, the distinction between air showers initiated by γ-rays and those initiated by cosmic rays was determined. Additionally, a Quality Factor was introduced to assess the telescope’s ability to suppress the background and to provide a more effective characterization of its performance.
{"title":"Gamma/Hadron Separation Method for the HADAR Experiment","authors":"Yang-Zhao Ren, Tian-Lu Chen, You-Liang Feng, Dan-Zeng Luo-Bu, Yi-Qing Guo, Cheng Liu, Qi Gao, Mao-Yuan Liu, Xiang-Li Qian, Ya-Ping Wang, Zi-Hao Zhang, Xin-Long Li, Qing-Yuan Hou, Heng-Jiao Liu, Qing-Qian Zhou, Shan-Jie Shu","doi":"10.1088/1674-4527/ad23cc","DOIUrl":"https://doi.org/10.1088/1674-4527/ad23cc","url":null,"abstract":"Ground-based arrays of imaging atmospheric Cherenkov telescopes (IACTs) are the most sensitive <italic toggle=\"yes\">γ</italic>-ray detectors for energies of approximately 100 GeV and above. One such IACT is the High Altitude Detection of Astronomical Radiation (HADAR) experiment, which uses a large aperture refractive water lens system to capture atmospheric Cherenkov photons (i.e., the imaging atmospheric Cherenkov technique). The telescope array has a low threshold energy and large field of view, and can continuously scan the area of the sky being observed, which is conducive to monitoring and promptly responding to transient phenomena. The process of <italic toggle=\"yes\">γ</italic>-hadron separation is essential in very-high-energy (>30 GeV) <italic toggle=\"yes\">γ</italic>-ray astronomy and is a key factor for the successful utilization of IACTs. In this study, Monte Carlo simulations were carried out to model the response of cosmic rays within the HADAR detectors. By analyzing the Hillas parameters and the distance between the event core and the telescope, the distinction between air showers initiated by <italic toggle=\"yes\">γ</italic>-rays and those initiated by cosmic rays was determined. Additionally, a Quality Factor was introduced to assess the telescope’s ability to suppress the background and to provide a more effective characterization of its performance.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"12 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140003876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Gamma-ray bursts (GRBs) are among the brightest objects in the Universe and, hence, can be observed up to a very high redshift. Properly calibrated empirical correlations between intensity and spectral correlations of GRBs can be used to estimate the cosmological parameters. However, the possibility of the evolution of GRBs with redshift is a long-standing puzzle. In this work, we used 162 long-duration GRBs to determine whether GRBs below and above a certain redshift have different properties. The GRBs are split into two groups, and we fit the Amati relation for each group separately. Our findings demonstrate that estimations of the Amati parameters for the two groups are substantially dissimilar. We perform simulations to investigate whether the selection effects could cause the difference. Our analysis shows that the differences may be either intrinsic or due to systematic errors in the data, and the selection effects are not their true origin. However, in-depth analysis with a new data set comprised of 119 long GRBs shows that intrinsic scatter may partly be responsible for such effects.
伽马射线暴（GRB）是宇宙中最亮的天体之一，因此可以观测到很高的红移。经适当校准的伽马射线暴强度和光谱相关性之间的经验相关性可用来估算宇宙学参数。然而，GRB随红移演化的可能性是一个长期存在的谜题。在这项工作中，我们利用 162 个长持续时间 GRB 来确定低于和高于某一红移的 GRB 是否具有不同的性质。GRB被分成两组，我们分别拟合了每组的阿马蒂关系。我们的研究结果表明，两组的阿马蒂参数估计结果大相径庭。我们进行了模拟，研究选择效应是否会导致这种差异。我们的分析表明，差异可能是内在的，也可能是由于数据的系统误差造成的，选择效应并不是其真正的根源。然而，利用由 119 个长 GRB 组成的新数据集进行的深入分析表明，内在散射可能是造成这种效应的部分原因。
{"title":"Investigating the Evolution of Amati Parameters with Redshift","authors":"Meghendra Singh, Darshan Singh, Kanhaiya Lal Pandey, Dinkar Verma, Shashikant Gupta","doi":"10.1088/1674-4527/ad0fd5","DOIUrl":"https://doi.org/10.1088/1674-4527/ad0fd5","url":null,"abstract":"Gamma-ray bursts (GRBs) are among the brightest objects in the Universe and, hence, can be observed up to a very high redshift. Properly calibrated empirical correlations between intensity and spectral correlations of GRBs can be used to estimate the cosmological parameters. However, the possibility of the evolution of GRBs with redshift is a long-standing puzzle. In this work, we used 162 long-duration GRBs to determine whether GRBs below and above a certain redshift have different properties. The GRBs are split into two groups, and we fit the Amati relation for each group separately. Our findings demonstrate that estimations of the Amati parameters for the two groups are substantially dissimilar. We perform simulations to investigate whether the selection effects could cause the difference. Our analysis shows that the differences may be either intrinsic or due to systematic errors in the data, and the selection effects are not their true origin. However, in-depth analysis with a new data set comprised of 119 long GRBs shows that intrinsic scatter may partly be responsible for such effects.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"30 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139507345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-12-20DOI: 10.1088/1674-4527/ad1793
Li Shao, Hu Zhan, Chao Liu, Haonan Chi, Qiuyan Luo, Huaipu Mu, Wenzhong Shi
We tested a new model of CMOS detector manufactured by the Gpixel Inc, for potential space astronomical application. In laboratory, we obtain some bias images under the typical application environment. In these bias images, clear random row noise pattern is observed. The row noise also contains some characteristic spatial frequencies. We quantitatively estimated the impact of this feature to photometric measurements, by making simulated images. We compared different bias noise types under strict parameter control. The result shows the row noise will significantly deteriorate the photometric accuracy. It effectively increases the readout noise by a factor of 2 to 10. However, if it is properly removed, the image quality and photometric accuracy will be significantly improved.
{"title":"The impact of bias row noise to photometric accuracy: case study based on a scientific CMOS detector","authors":"Li Shao, Hu Zhan, Chao Liu, Haonan Chi, Qiuyan Luo, Huaipu Mu, Wenzhong Shi","doi":"10.1088/1674-4527/ad1793","DOIUrl":"https://doi.org/10.1088/1674-4527/ad1793","url":null,"abstract":"\u0000 We tested a new model of CMOS detector manufactured by the Gpixel Inc, for potential space astronomical application. In laboratory, we obtain some bias images under the typical application environment. In these bias images, clear random row noise pattern is observed. The row noise also contains some characteristic spatial frequencies. We quantitatively estimated the impact of this feature to photometric measurements, by making simulated images. We compared different bias noise types under strict parameter control. The result shows the row noise will significantly deteriorate the photometric accuracy. It effectively increases the readout noise by a factor of 2 to 10. However, if it is properly removed, the image quality and photometric accuracy will be significantly improved.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"42 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138957455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-12-19DOI: 10.1088/1674-4527/ad16fb
P. Vemareddy, Jorn Warnecke, P.A. Bourdin
Coronal magnetic fields evolve quasi statically over long time scales and dynamically over short time scales. As of now there exists no regular measurements of coronal magnetic fields, and therefore generating the coronal magnetic field evolution using the observations of the magnetic field at the photosphere is of fundamental requirement to understand the origin of the transient phenomena from the solar active regions. Using the magnetofriction (MF) approach, we aim to simulate the coronal field evolution in the solar active region 11429. The MF method is implemented in open source PC along with a driver module to drive the initial field with different boundary conditions prescribed from observed vector magnetic fields at the photosphere. In order to work with vector potential and the observations, we prescribe three types of bottom boundary drivers with varying free-magnetic energy. The MF simulation reproduces the magnetic structure which better matches to the sigmoidal morphology exhibited by AIA images at the pre-eruptive time. We found that the already sheared field further driven by the sheared magnetic field will maintain and further build the highly sheared coronal magnetic configuration such as seen in AR 11429. Data-driven MF simulation is a viable tool to generate the coronal magnetic field evolution capturing the formation of the twisted flux rope and its eruption.
日冕磁场在长时间尺度上呈准静态演变，在短时间尺度上呈动态演变。目前还没有日冕磁场的定期测量数据，因此利用光球磁场观测数据生成日冕磁场演化，是了解太阳活动区瞬态现象起源的基本要求。利用磁摩擦（MF）方法，我们旨在模拟太阳活动区 11429 的日冕磁场演变。MF 方法是在开源的 PC 中实现的，同时还有一个驱动模块，用于根据光球观测到的矢量磁场规定的不同边界条件驱动初始磁场。为了与矢量磁势和观测结果配合使用，我们规定了三种具有不同自由磁能的底部边界驱动条件。中频模拟再现的磁场结构更符合 AIA 图像显示的爆发前的正弦波形态。我们发现，在剪切磁场的进一步驱动下，已经剪切的磁场将保持并进一步形成高度剪切的日冕磁结构，如在AR 11429中看到的那样。数据驱动的中频模拟是生成日冕磁场演化的可行工具，它捕捉到了扭曲磁通绳的形成及其爆发。
{"title":"Data-driven simulations of magnetic field evolution in Active Region 11429: Magneto-friction method using PENCIL code","authors":"P. Vemareddy, Jorn Warnecke, P.A. Bourdin","doi":"10.1088/1674-4527/ad16fb","DOIUrl":"https://doi.org/10.1088/1674-4527/ad16fb","url":null,"abstract":"\u0000 Coronal magnetic fields evolve quasi statically over long time scales and dynamically over short time scales. As of now there exists no regular measurements of coronal magnetic fields, and therefore generating the coronal magnetic field evolution using the observations of the magnetic field at the photosphere is of fundamental requirement to understand the origin of the transient phenomena from the solar active regions. Using the magnetofriction (MF) approach, we aim to simulate the coronal field evolution in the solar active region 11429. The MF method is implemented in open source PC along with a driver module to drive the initial field with different boundary conditions prescribed from observed vector magnetic fields at the photosphere. In order to work with vector potential and the observations, we prescribe three types of bottom boundary drivers with varying free-magnetic energy. The MF simulation reproduces the magnetic structure which better matches to the sigmoidal morphology exhibited by AIA images at the pre-eruptive time. We found that the already sheared field further driven by the sheared magnetic field will maintain and further build the highly sheared coronal magnetic configuration such as seen in AR 11429. Data-driven MF simulation is a viable tool to generate the coronal magnetic field evolution capturing the formation of the twisted flux rope and its eruption.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":" 20","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138959881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-12-19DOI: 10.1088/1674-4527/ad0ded
Noam Soker
I analyze a new X-ray image of the youngest supernova remnant (SNR) in the Galaxy, which is the type Ia SNR G1.9+0.3, and reveal a very clear point-symmetrical structure. Since explosion models of type Ia supernovae (SNe Ia) do not form such morphologies, the point-symmetrical morphology must come from the circumstellar material (CSM) into which the ejecta expands. The large-scale point-symmetry that I identify and the known substantial deceleration of the ejecta of SNR G1.9+0.3 suggest a relatively massive CSM of ≳1M⊙. I argue that the most likely explanation is the explosion of this SN Ia into a planetary nebula. The scenario that predicts a large fraction of SN Ia inside PNe (SNIPs) is the core degenerate scenario. Other SN Ia scenarios might lead to only a very small fraction of SNIPs or none at all.
{"title":"Point-symmetry in SNR G1.9+0.3: A Supernova that Destroyed its Planetary Nebula Progenitor","authors":"Noam Soker","doi":"10.1088/1674-4527/ad0ded","DOIUrl":"https://doi.org/10.1088/1674-4527/ad0ded","url":null,"abstract":"I analyze a new X-ray image of the youngest supernova remnant (SNR) in the Galaxy, which is the type Ia SNR G1.9+0.3, and reveal a very clear point-symmetrical structure. Since explosion models of type Ia supernovae (SNe Ia) do not form such morphologies, the point-symmetrical morphology must come from the circumstellar material (CSM) into which the ejecta expands. The large-scale point-symmetry that I identify and the known substantial deceleration of the ejecta of SNR G1.9+0.3 suggest a relatively massive CSM of ≳1<italic toggle=\"yes\">M</italic>\u0000<sub>⊙</sub>. I argue that the most likely explanation is the explosion of this SN Ia into a planetary nebula. The scenario that predicts a large fraction of SN Ia inside PNe (SNIPs) is the core degenerate scenario. Other SN Ia scenarios might lead to only a very small fraction of SNIPs or none at all.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"3 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139054967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-12-16DOI: 10.1088/1674-4527/ad1659
Zehao Zheng, Yang Liu, D. Shen, Fan Feng, Jiulong Liu, Yuexin Ma, Xiangwei Zhu
In today's society, there is a wide demand for high-precision and high-stability time service in the fields of electric power, communication, transportation and finance. At present, the time standard in various countries is mainly based on atomic clocks, but the frequency drift of atomic clocks will affect the long-term stability performance. Compared with atomic clocks, millisecond pulsars have better long-term stability and can complement with the excellent short-term stability of atomic clocks. In order to improve the long-term stability of the atomic time scale, and then improve the timing accuracy, this paper proposes an algorithm for steering the Atomic clock ensemble (ACE) by Ensemble pulsar time (EPT) based on Digital phase locked loop (DPLL). Firstly, the ACE and EPT are generated by ALGOS algorithm, then the ACE is steered by EPT based on DPLL to calibrate the long-term frequency drift of the atomic clock, so that the generated steered atomic time follows both the short-term stability characteristics of ACE and the long-term stability characteristics of EPT, and finally, the steered atomic time is used to calibrate the local cesium clock. The experimental results show that the long-term stability of atomic time after steering is improved by 2 orders of magnitude compared with that before steering, and the daily drift of local cesium clock after calibration is less than 9.47ns in 3 years, 3 orders of magnitude higher than that before calibration on accuracy.
{"title":"Research on Pulsar Time Steered Atomic Time Algorithm Based on DPLL","authors":"Zehao Zheng, Yang Liu, D. Shen, Fan Feng, Jiulong Liu, Yuexin Ma, Xiangwei Zhu","doi":"10.1088/1674-4527/ad1659","DOIUrl":"https://doi.org/10.1088/1674-4527/ad1659","url":null,"abstract":"\u0000 In today's society, there is a wide demand for high-precision and high-stability time service in the fields of electric power, communication, transportation and finance. At present, the time standard in various countries is mainly based on atomic clocks, but the frequency drift of atomic clocks will affect the long-term stability performance. Compared with atomic clocks, millisecond pulsars have better long-term stability and can complement with the excellent short-term stability of atomic clocks. In order to improve the long-term stability of the atomic time scale, and then improve the timing accuracy, this paper proposes an algorithm for steering the Atomic clock ensemble (ACE) by Ensemble pulsar time (EPT) based on Digital phase locked loop (DPLL). Firstly, the ACE and EPT are generated by ALGOS algorithm, then the ACE is steered by EPT based on DPLL to calibrate the long-term frequency drift of the atomic clock, so that the generated steered atomic time follows both the short-term stability characteristics of ACE and the long-term stability characteristics of EPT, and finally, the steered atomic time is used to calibrate the local cesium clock. The experimental results show that the long-term stability of atomic time after steering is improved by 2 orders of magnitude compared with that before steering, and the daily drift of local cesium clock after calibration is less than 9.47ns in 3 years, 3 orders of magnitude higher than that before calibration on accuracy.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"50 8","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138995830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
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