Pub Date : 2023-10-01DOI: 10.3847/1538-4365/acf669
Emma Perracchione, Fabiana Camattari, Anna Volpara, Paolo Massa, Anna Maria Massone, Michele Piana
Abstract CLEAN is an iterative deconvolution method for radio and hard-X-ray solar imaging. In a specific step of its pipeline, CLEAN requires the convolution between an idealized version of the instrumental point-spread function (PSF), and a map collecting point sources located at positions from where most of the flaring radiation is emitted. This step has highly heuristic motivations and the shape of the idealized PSF, which depends on the user’s choice, impacts the shape of the reconstruction. This study introduces a user-independent release of CLEAN for image reconstruction from observations recorded by the Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter. Specifically, we show here that this unbiased release of CLEAN outperforms the standard version of the algorithm, with reconstructions in line with the ones offered by other imaging methods developed in the STIX framework.
{"title":"Unbiased CLEAN for STIX in Solar Orbiter","authors":"Emma Perracchione, Fabiana Camattari, Anna Volpara, Paolo Massa, Anna Maria Massone, Michele Piana","doi":"10.3847/1538-4365/acf669","DOIUrl":"https://doi.org/10.3847/1538-4365/acf669","url":null,"abstract":"Abstract CLEAN is an iterative deconvolution method for radio and hard-X-ray solar imaging. In a specific step of its pipeline, CLEAN requires the convolution between an idealized version of the instrumental point-spread function (PSF), and a map collecting point sources located at positions from where most of the flaring radiation is emitted. This step has highly heuristic motivations and the shape of the idealized PSF, which depends on the user’s choice, impacts the shape of the reconstruction. This study introduces a user-independent release of CLEAN for image reconstruction from observations recorded by the Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter. Specifically, we show here that this unbiased release of CLEAN outperforms the standard version of the algorithm, with reconstructions in line with the ones offered by other imaging methods developed in the STIX framework.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135707037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/1538-4365/acec47
Anu Sreedevi, Bibhuti Kumar Jha, Bidya Binay Karak, Dipankar Banerjee
Abstract Bipolar magnetic regions (BMRs) provide crucial information about solar magnetism. They exhibit varying morphology and magnetic properties throughout their lifetime, and studying these properties can provide valuable insights into the workings of the solar dynamo. The majority of previous studies have counted every detected BMR as a new one and have not been able to study the full life history of each BMR. To address this issue, we have developed Automatic Tracking Algorithm for BMRs (AutoTAB) that tracks the BMRs for their entire lifetime or throughout their disk passage. AutoTAB uses the binary maps of detected BMRs and their overlapping criterion to automatically track the regions. In this first article of this project, we provide a detailed description of the working of the algorithm and evaluate its strengths and weaknesses by comparing it with existing algorithms. AutoTAB excels in tracking even for the small BMRs (with a flux of ∼10 20 Mx), and it has successfully tracked 9152 BMRs over the last two solar cycles (1996–2020), providing a comprehensive data set that depicts the evolution of various properties for each BMR. The tracked BMRs exhibit the well-known butterfly diagram and 11 yr solar cycle variation, except for small BMRs, which appear at all phases of the solar cycle and show a weak latitudinal dependence. Finally, we discuss the possibility of adapting our algorithm to other data sets and expanding the technique to track other solar features in the future.
{"title":"AutoTAB: Automatic Tracking Algorithm for Bipolar Magnetic Regions","authors":"Anu Sreedevi, Bibhuti Kumar Jha, Bidya Binay Karak, Dipankar Banerjee","doi":"10.3847/1538-4365/acec47","DOIUrl":"https://doi.org/10.3847/1538-4365/acec47","url":null,"abstract":"Abstract Bipolar magnetic regions (BMRs) provide crucial information about solar magnetism. They exhibit varying morphology and magnetic properties throughout their lifetime, and studying these properties can provide valuable insights into the workings of the solar dynamo. The majority of previous studies have counted every detected BMR as a new one and have not been able to study the full life history of each BMR. To address this issue, we have developed Automatic Tracking Algorithm for BMRs (AutoTAB) that tracks the BMRs for their entire lifetime or throughout their disk passage. AutoTAB uses the binary maps of detected BMRs and their overlapping criterion to automatically track the regions. In this first article of this project, we provide a detailed description of the working of the algorithm and evaluate its strengths and weaknesses by comparing it with existing algorithms. AutoTAB excels in tracking even for the small BMRs (with a flux of ∼10 20 Mx), and it has successfully tracked 9152 BMRs over the last two solar cycles (1996–2020), providing a comprehensive data set that depicts the evolution of various properties for each BMR. The tracked BMRs exhibit the well-known butterfly diagram and 11 yr solar cycle variation, except for small BMRs, which appear at all phases of the solar cycle and show a weak latitudinal dependence. Finally, we discuss the possibility of adapting our algorithm to other data sets and expanding the technique to track other solar features in the future.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136117643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/1538-4365/ace96a
Kai Feng, Long Xu, Dong Zhao, Sixuan Liu, Xin Huang
Abstract Timely solar flare forecasting is challenged by the delay of transmitting vast amounts of data from the satellite to the ground. To avoid this delay, it is expected that forecasting models will be deployed on satellites. Thus, transmitting forecasting results instead of huge volumes of observation data would greatly save network bandwidth and reduce forecasting delay. However, deep-learning models have a huge number of parameters so they need large memory and strong computing power, which hinders their deployment on satellites with limited memory and computing resources. Therefore, there is a great need to compress forecasting models for efficient deployment on satellites. First, three typical compression methods, namely knowledge distillation, pruning, and quantization, are examined individually for compressing of solar flare forecasting models. And then, an assembled compression model is proposed for better compressing solar flare forecasting models. The experimental results demonstrate that the assembled compression model can compress a pretrained solar flare forecasting model to only 1.67% of its original size while maintaining forecasting accuracy.
{"title":"Toward Model Compression for a Deep Learning–Based Solar Flare Forecast on Satellites","authors":"Kai Feng, Long Xu, Dong Zhao, Sixuan Liu, Xin Huang","doi":"10.3847/1538-4365/ace96a","DOIUrl":"https://doi.org/10.3847/1538-4365/ace96a","url":null,"abstract":"Abstract Timely solar flare forecasting is challenged by the delay of transmitting vast amounts of data from the satellite to the ground. To avoid this delay, it is expected that forecasting models will be deployed on satellites. Thus, transmitting forecasting results instead of huge volumes of observation data would greatly save network bandwidth and reduce forecasting delay. However, deep-learning models have a huge number of parameters so they need large memory and strong computing power, which hinders their deployment on satellites with limited memory and computing resources. Therefore, there is a great need to compress forecasting models for efficient deployment on satellites. First, three typical compression methods, namely knowledge distillation, pruning, and quantization, are examined individually for compressing of solar flare forecasting models. And then, an assembled compression model is proposed for better compressing solar flare forecasting models. The experimental results demonstrate that the assembled compression model can compress a pretrained solar flare forecasting model to only 1.67% of its original size while maintaining forecasting accuracy.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134934293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/1538-4365/acef1b
Ruihui Wang, Jie Jiang, Yukun Luo
Abstract Recent studies indicate that a small number of rogue solar active regions (ARs) may have a significant impact on the end-of-cycle polar field and the long-term behavior of solar activity. The impact of individual ARs can be qualified based on their magnetic field distribution. This motivates us to build a live homogeneous AR database in a series of papers. As the first of the series, we develop a method to automatically detect ARs from 1996 onward based on SOHO/MDI and SDO/HMI synoptic magnetograms. The method shows its advantages in excluding decayed ARs and unipolar regions and being compatible with any available synoptic magnetograms. The identified AR flux and area are calibrated based on the cotemporal SDO/HMI and SOHO/MDI data. The homogeneity and reliability of the database are further verified by comparing it with other relevant databases. We find that ARs with weaker flux have a weaker cycle dependence. Stronger ARs show a weaker cycle 24 compared with cycle 23. Several basic parameters, namely, the location, area, and flux of negative and positive polarities of the identified ARs, are provided in the paper. This paves the way for ARs’ new parameters quantifying the impact on the long-term behavior of solar activity to be presented in the subsequent paper of the series. The constantly updated database covering more than two full solar cycles will be beneficial for the understanding and prediction of the solar cycle. The database and the detection codes are accessible online.
{"title":"Toward a Live Homogeneous Database of Solar Active Regions Based on SOHO/MDI and SDO/HMI Synoptic Magnetograms. I. Automatic Detection and Calibration","authors":"Ruihui Wang, Jie Jiang, Yukun Luo","doi":"10.3847/1538-4365/acef1b","DOIUrl":"https://doi.org/10.3847/1538-4365/acef1b","url":null,"abstract":"Abstract Recent studies indicate that a small number of rogue solar active regions (ARs) may have a significant impact on the end-of-cycle polar field and the long-term behavior of solar activity. The impact of individual ARs can be qualified based on their magnetic field distribution. This motivates us to build a live homogeneous AR database in a series of papers. As the first of the series, we develop a method to automatically detect ARs from 1996 onward based on SOHO/MDI and SDO/HMI synoptic magnetograms. The method shows its advantages in excluding decayed ARs and unipolar regions and being compatible with any available synoptic magnetograms. The identified AR flux and area are calibrated based on the cotemporal SDO/HMI and SOHO/MDI data. The homogeneity and reliability of the database are further verified by comparing it with other relevant databases. We find that ARs with weaker flux have a weaker cycle dependence. Stronger ARs show a weaker cycle 24 compared with cycle 23. Several basic parameters, namely, the location, area, and flux of negative and positive polarities of the identified ARs, are provided in the paper. This paves the way for ARs’ new parameters quantifying the impact on the long-term behavior of solar activity to be presented in the subsequent paper of the series. The constantly updated database covering more than two full solar cycles will be beneficial for the understanding and prediction of the solar cycle. The database and the detection codes are accessible online.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134934524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/1538-4365/acf578
Mallory Molina, Laura Duffy, Michael Eracleous, Mary Ogborn, Mary E. Kaldor, Renbin Yan, Caryl Gronwall, Robin Ciardullo, Nikhil Ajgaonkar
Abstract We present the the new Swift/UVOT+MaNGA (SwiM) catalog (SwiM_v4.1). SwiM_v4.1 is designed to study star formation and dust attenuation within nearby galaxies given the unique overlap of Swift/UVOT near-ultraviolet (NUV) imaging and MaNGA integral field optical spectroscopy. SwiM_v4.1 comprises 559 objects, ∼4 times more than the original SwiM catalog (SwiM_v3.1), spans the redshift range z ≈ 0.0002–0.1482, and provides a more diverse and rich sample. Approximately 5% of the final MaNGA sample is included in SwiM_v4.1, and 42% of the SwiM_v4.1 galaxies are cross-listed with other well-known catalogs. We present the same data as SwiM_v3.1, including UVOT images, Sloan Digital Sky Survey (SDSS) images, and MaNGA emission-line and spectral index maps with the same pixel size and angular resolution for each galaxy, and a file containing galaxy and observational properties. We designed SwiM_v4.1 to be unbiased, which resulted in some objects having low signal-to-noise ratios in their MaNGA or Swift data. We addressed this by providing a new file containing the fraction of science-ready pixels in each MaNGA emission-line map, and the integrated flux and inverse variance for all three NUV filters. The uniform angular resolution and sampling in SwiM_v4.1 will help answer a number of scientific questions, including constraining quenching and attenuation in the local Universe and studying the effects of black hole feedback. The galaxy maps, catalog files, and their associated data models are publicly released on the SDSS website (a description of the SwiM VAC is provided at https://www.sdss4.org/dr17/data_access/value-added-catalogs/?vac_id=swift-manga-value-added-catalog , and the data are stored on the SDSS Science Archive Server at https://data.sdss.org/sas/dr17/manga/swim/v4.1/ ).
{"title":"The New Swift/UVOT+MaNGA (SwiM) Value-added Catalog","authors":"Mallory Molina, Laura Duffy, Michael Eracleous, Mary Ogborn, Mary E. Kaldor, Renbin Yan, Caryl Gronwall, Robin Ciardullo, Nikhil Ajgaonkar","doi":"10.3847/1538-4365/acf578","DOIUrl":"https://doi.org/10.3847/1538-4365/acf578","url":null,"abstract":"Abstract We present the the new Swift/UVOT+MaNGA (SwiM) catalog (SwiM_v4.1). SwiM_v4.1 is designed to study star formation and dust attenuation within nearby galaxies given the unique overlap of Swift/UVOT near-ultraviolet (NUV) imaging and MaNGA integral field optical spectroscopy. SwiM_v4.1 comprises 559 objects, ∼4 times more than the original SwiM catalog (SwiM_v3.1), spans the redshift range z ≈ 0.0002–0.1482, and provides a more diverse and rich sample. Approximately 5% of the final MaNGA sample is included in SwiM_v4.1, and 42% of the SwiM_v4.1 galaxies are cross-listed with other well-known catalogs. We present the same data as SwiM_v3.1, including UVOT images, Sloan Digital Sky Survey (SDSS) images, and MaNGA emission-line and spectral index maps with the same pixel size and angular resolution for each galaxy, and a file containing galaxy and observational properties. We designed SwiM_v4.1 to be unbiased, which resulted in some objects having low signal-to-noise ratios in their MaNGA or Swift data. We addressed this by providing a new file containing the fraction of science-ready pixels in each MaNGA emission-line map, and the integrated flux and inverse variance for all three NUV filters. The uniform angular resolution and sampling in SwiM_v4.1 will help answer a number of scientific questions, including constraining quenching and attenuation in the local Universe and studying the effects of black hole feedback. The galaxy maps, catalog files, and their associated data models are publicly released on the SDSS website (a description of the SwiM VAC is provided at https://www.sdss4.org/dr17/data_access/value-added-catalogs/?vac_id=swift-manga-value-added-catalog , and the data are stored on the SDSS Science Archive Server at https://data.sdss.org/sas/dr17/manga/swim/v4.1/ ).","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135605278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Abstract Cosmology constraints serve as a crucial criterion in discriminating cosmological models. The traditional combined method to constrain the cosmological parameters designates the corresponding theoretical value and observational data as functions of redshift; however, sometimes the redshift cannot be measured directly, or the measurement error is large, or the definition of redshift is controversial. In this paper, we propose a novel joint method to constrain parameters that eliminates the redshift z and makes full use of the multiple observables 1,obs,2,obs,⋯,M,obs spanning in M -dimensional joint observable space. Considering the generality of the mathematical form of the cosmological models and the guidance from low to high dimensions, we first validate our method in a 3D joint observable space spanned by H ( z ), f σ 8 ( z ), and D A ( z ), where the three coordinates can be considered redshift-free measurements of the same celestial body (or shared-redshift data-reconstructed model independently). Our results are consistent with the traditional combined method but with lower errors, yielding H 0 = 68.7 ± 0.1 km s −1 Mpc −1 , Ω m 0 = 0.289 ± 0.003, and σ 8 = 0.82 ± 0.01 and showing alleviated parametric degeneracies to some extent. In principle, our joint constraint method allows an extended form keeping the redshift information as an independent coordinate and can also be readily degraded to the form of a traditional combined method to constrain parameters.
宇宙学约束是判别宇宙学模型的重要标准。传统的联合约束宇宙学参数的方法将相应的理论值和观测数据指定为红移的函数;然而，有时红移不能直接测量，或测量误差较大，或红移的定义存在争议。在本文中，我们提出了一种新的联合方法来约束参数，该方法消除了红移z，并充分利用了M维联合可观测空间中生成的多个可观测值1,obs，2,obs，⋯，M, obs。考虑到宇宙学模型数学形式的一般性和从低维到高维的指导，我们首先在由H (z)， f σ 8 (z)和da (z)组成的三维联合可观测空间中验证了我们的方法，其中三个坐标可以被认为是同一天体的无红移测量(或独立的共享红移数据重建模型)。我们的结果与传统的组合方法一致，但误差更小，得到H 0 = 68.7±0.1 km s−1 Mpc−1，Ω m 0 = 0.289±0.003，σ 8 = 0.82±0.01，并在一定程度上减轻了参数简并性。原则上，我们的联合约束方法允许扩展形式保持红移信息作为一个独立的坐标，也可以很容易地退化到传统的组合方法的形式来约束参数。
{"title":"Novel Cosmological Joint Constraints in Multidimensional Observable Space with Redshift-free Inferences","authors":"Wei Hong, Kang Jiao, Yu-Chen Wang, Tingting Zhang, Tong-Jie 同杰 Zhang 张","doi":"10.3847/1538-4365/acf654","DOIUrl":"https://doi.org/10.3847/1538-4365/acf654","url":null,"abstract":"Abstract Cosmology constraints serve as a crucial criterion in discriminating cosmological models. The traditional combined method to constrain the cosmological parameters designates the corresponding theoretical value and observational data as functions of redshift; however, sometimes the redshift cannot be measured directly, or the measurement error is large, or the definition of redshift is controversial. In this paper, we propose a novel joint method to constrain parameters that eliminates the redshift z and makes full use of the multiple observables <?CDATA $left{{{ mathcal F }}_{1,mathrm{obs}},{{ mathcal F }}_{2,mathrm{obs}},cdots ,{{ mathcal F }}_{M,mathrm{obs}}right}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mfenced close=\"}\" open=\"{\"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant=\"italic\"></mml:mi> </mml:mrow> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>,</mml:mo> <mml:mi>obs</mml:mi> </mml:mrow> </mml:msub> <mml:mo>,</mml:mo> <mml:msub> <mml:mrow> <mml:mi mathvariant=\"italic\"></mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>,</mml:mo> <mml:mi>obs</mml:mi> </mml:mrow> </mml:msub> <mml:mo>,</mml:mo> <mml:mo>⋯</mml:mo> <mml:mo>,</mml:mo> <mml:msub> <mml:mrow> <mml:mi mathvariant=\"italic\"></mml:mi> </mml:mrow> <mml:mrow> <mml:mi>M</mml:mi> <mml:mo>,</mml:mo> <mml:mi>obs</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:mfenced> </mml:math> spanning in M -dimensional joint observable space. Considering the generality of the mathematical form of the cosmological models and the guidance from low to high dimensions, we first validate our method in a 3D joint observable space spanned by H ( z ), f σ 8 ( z ), and D A ( z ), where the three coordinates can be considered redshift-free measurements of the same celestial body (or shared-redshift data-reconstructed model independently). Our results are consistent with the traditional combined method but with lower errors, yielding H 0 = 68.7 ± 0.1 km s −1 Mpc −1 , Ω m 0 = 0.289 ± 0.003, and σ 8 = 0.82 ± 0.01 and showing alleviated parametric degeneracies to some extent. In principle, our joint constraint method allows an extended form keeping the redshift information as an independent coordinate and can also be readily degraded to the form of a traditional combined method to constrain parameters.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135706502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/1538-4365/acee6b
Y. P. 益鹏 Zou 邹, J. S. 江水 Zhang 张, C. Henkel, D. Romano, W. 玮 Liu 刘, Y. H. 映慧 Zheng 郑, Y. T. 耀庭 Yan 闫, J. L. 家梁 Chen 陈, Y. X. 友鑫 Wang 汪, J. Y. 洁瑜 Zhao 赵
Abstract To investigate the relative amount of ejecta from high-mass versus intermediate-mass stars and to trace the chemical evolution of the Galaxy, we have performed a systematic study of Galactic interstellar 18 O/ 17 O ratios toward a sample of 421 molecular clouds with IRAM 30 m and the 10 m Submillimeter Telescope, covering a galactocentric distance range of ∼1–22 kpc. The results presented in this paper are based on the J = 2–1 transition and encompass 364 sources showing both C 18 O and C 17 O detections. The previously suggested 18 O/ 17 O gradient is confirmed. For the 41 sources detected with both facilities, good agreement is obtained. A correlation of the 18 O/ 17 O ratios with heliocentric distance is not found, indicating that beam dilution and linear beam sizes are not relevant. For the subsample of IRAM 30 m high-mass star-forming regions with accurate parallax distances, an unweighted fit gives 18 O/ 17 O = (0.12 ± 0.02) R GC + (2.38 ± 0.13) with a correlation coefficient of R = 0.67. While the slope is consistent with our J = 1–0 measurement, the ratios are systematically lower. This should be caused by larger optical depths of C 18 O 2–1 lines with respect to the corresponding 1–0 transitions, which is supported by RADEX calculations and the fact that C 18 O/C 17 O is positively correlated with 13 CO/C 18 O. When we consider that optical depth effects with C 18 O J = 2–1 typically reach an optical depth of ∼0.5, the corrected 18 O/ 17 O ratios from the J = 1–0 and J = 2–1 lines are consistent. A good numerical fit to the data is provided by the MWG-12 model, which includes both rotating stars and novae.
为了研究高质量恒星与中质量恒星的相对喷射量，并追踪银河系的化学演化，我们利用IRAM 30 m和10 m亚毫米望远镜对421个分子云样本进行了银河系18 O/ 17 O比的系统研究，覆盖了星系中心距离范围为1-22 kpc。本文给出的结果是基于J = 2-1跃迁，包括364个源，显示c18o和c17o检测。先前建议的18 O/ 17 O梯度被确认。对于用这两种设备检测到的41个源，得到了很好的一致性。没有发现18 O/ 17 O比值与日心距离的相关性，表明光束稀释和线性光束尺寸无关。对于具有精确视差距离的IRAM 30 m高质量恒星形成区域的子样本，未加权拟合得到18 O/ 17 O =(0.12±0.02)R GC +(2.38±0.13)，相关系数R = 0.67。虽然斜率与我们的J = 1-0测量结果一致，但比率系统性地降低了。这应该引起更大的光学深度C 18 O 2 - 1线对应的1 - 0转换,由RADEX支持计算17和18 O / C O与13 CO / C 18 O .呈正相关,当我们考虑到光学深度影响C 18 O J = 2:1通常达成光学深度0.5∼,纠正17 18 O / O比率从J = 1 - 0和J = 2行是一致的。MWG-12模型提供了一个很好的数值拟合数据，其中包括旋转恒星和新星。
{"title":"A Systematic Observational Study on Galactic Interstellar Ratio <sup>18</sup>O/<sup>17</sup>O. II. C<sup>18</sup>O and C<sup>17</sup>O J = 2–1 Data Analysis","authors":"Y. P. 益鹏 Zou 邹, J. S. 江水 Zhang 张, C. Henkel, D. Romano, W. 玮 Liu 刘, Y. H. 映慧 Zheng 郑, Y. T. 耀庭 Yan 闫, J. L. 家梁 Chen 陈, Y. X. 友鑫 Wang 汪, J. Y. 洁瑜 Zhao 赵","doi":"10.3847/1538-4365/acee6b","DOIUrl":"https://doi.org/10.3847/1538-4365/acee6b","url":null,"abstract":"Abstract To investigate the relative amount of ejecta from high-mass versus intermediate-mass stars and to trace the chemical evolution of the Galaxy, we have performed a systematic study of Galactic interstellar 18 O/ 17 O ratios toward a sample of 421 molecular clouds with IRAM 30 m and the 10 m Submillimeter Telescope, covering a galactocentric distance range of ∼1–22 kpc. The results presented in this paper are based on the J = 2–1 transition and encompass 364 sources showing both C 18 O and C 17 O detections. The previously suggested 18 O/ 17 O gradient is confirmed. For the 41 sources detected with both facilities, good agreement is obtained. A correlation of the 18 O/ 17 O ratios with heliocentric distance is not found, indicating that beam dilution and linear beam sizes are not relevant. For the subsample of IRAM 30 m high-mass star-forming regions with accurate parallax distances, an unweighted fit gives 18 O/ 17 O = (0.12 ± 0.02) R GC + (2.38 ± 0.13) with a correlation coefficient of R = 0.67. While the slope is consistent with our J = 1–0 measurement, the ratios are systematically lower. This should be caused by larger optical depths of C 18 O 2–1 lines with respect to the corresponding 1–0 transitions, which is supported by RADEX calculations and the fact that C 18 O/C 17 O is positively correlated with 13 CO/C 18 O. When we consider that optical depth effects with C 18 O J = 2–1 typically reach an optical depth of ∼0.5, the corrected 18 O/ 17 O ratios from the J = 1–0 and J = 2–1 lines are consistent. A good numerical fit to the data is provided by the MWG-12 model, which includes both rotating stars and novae.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134934522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/1538-4365/acebe4
Woowon Byun, Minjin Kim, Yun-Kyeong Sheen, Dongseob Lee, Luis C. Ho, Jongwan Ko, Kwang-Il Seon, Hyunjin Shim, Dohyeong Kim, Yongjung Kim, Joon Hyeop Lee, Hyunjin Jeong, Jong-Hak Woo, Woong-Seob Jeong, Byeong-Gon Park, Sang Chul Kim, Yongseok Lee, Sang-Mok Cha, Hyunmi Song, Donghoon Son, Yujin Yang
Abstract We search for quasi-stellar objects (QSOs) in a wide area of the south ecliptic pole (SEP) field, which has been and will continue to be intensively explored through various space missions. For this purpose, we obtain deep broadband optical images of the SEP field covering an area of ∼14.5 × 14.5 deg 2 with the Korea Microlensing Telescope Network (KMTNet). The 5 σ detection limits for point sources in the BVRI bands are estimated to be ∼22.59, 22.60, 22.98, and 21.85 mag, respectively. Utilizing data from the Wide-field Infrared Survey Explorer, unobscured QSO candidates are selected among the optically pointlike sources using mid-infrared (MIR) and optical–MIR colors. To refine our selection further and eliminate any contamination not adequately removed by the color-based selection, we perform spectral energy distribution fitting with archival photometric data ranging from optical to MIR. As a result, we identify a total of 2383 unobscured QSO candidates in the SEP field. We also apply a similar method to the north ecliptic pole field using Pan-STARRS data and obtain a similar result of identifying 2427 candidates. The differential number count per area of our QSO candidates is in good agreement with those measured from spectroscopically confirmed ones in other fields. Finally, we compare the results with the literature and discuss how this work will impact future studies, especially upcoming space missions.
{"title":"Photometric Selection of Unobscured QSOs at the Ecliptic Poles: KMTNet in the South Field and Pan-STARRS in the North Field","authors":"Woowon Byun, Minjin Kim, Yun-Kyeong Sheen, Dongseob Lee, Luis C. Ho, Jongwan Ko, Kwang-Il Seon, Hyunjin Shim, Dohyeong Kim, Yongjung Kim, Joon Hyeop Lee, Hyunjin Jeong, Jong-Hak Woo, Woong-Seob Jeong, Byeong-Gon Park, Sang Chul Kim, Yongseok Lee, Sang-Mok Cha, Hyunmi Song, Donghoon Son, Yujin Yang","doi":"10.3847/1538-4365/acebe4","DOIUrl":"https://doi.org/10.3847/1538-4365/acebe4","url":null,"abstract":"Abstract We search for quasi-stellar objects (QSOs) in a wide area of the south ecliptic pole (SEP) field, which has been and will continue to be intensively explored through various space missions. For this purpose, we obtain deep broadband optical images of the SEP field covering an area of ∼14.5 × 14.5 deg 2 with the Korea Microlensing Telescope Network (KMTNet). The 5 σ detection limits for point sources in the BVRI bands are estimated to be ∼22.59, 22.60, 22.98, and 21.85 mag, respectively. Utilizing data from the Wide-field Infrared Survey Explorer, unobscured QSO candidates are selected among the optically pointlike sources using mid-infrared (MIR) and optical–MIR colors. To refine our selection further and eliminate any contamination not adequately removed by the color-based selection, we perform spectral energy distribution fitting with archival photometric data ranging from optical to MIR. As a result, we identify a total of 2383 unobscured QSO candidates in the SEP field. We also apply a similar method to the north ecliptic pole field using Pan-STARRS data and obtain a similar result of identifying 2427 candidates. The differential number count per area of our QSO candidates is in good agreement with those measured from spectroscopically confirmed ones in other fields. Finally, we compare the results with the literature and discuss how this work will impact future studies, especially upcoming space missions.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134935420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/1538-4365/acf127
L. F. Wang, Y. Li, Q. Li, X. Cheng, M. D. Ding
Abstract We report on the spectral features of the Si iv λ 1402.77, C ii λ 1334.53, and Mg ii h or k lines, formed in the layers from the transition region to the chromosphere, in three two-ribbon flares (with X, M, and C class) observed with IRIS. All three lines show significant redshifts within the main flare ribbons, which mainly originate from the chromospheric condensation during the flares. The average redshift velocities of the Si iv line within the main ribbons are 56.6, 25.6, and 10.5 km s −1 for the X-, M-, and C-class flares, respectively, which show a decreasing tendency with the flare class. The C ii and Mg ii lines show a similar tendency but with smaller velocities compared to the Si iv line. Additionally, the Mg ii h or k line shows a blue-wing enhancement in the three flares, in particular at the flare ribbon fronts, which is supposed to be caused by an upflow in the upper chromosphere due to the heating of the atmosphere. Moreover, the Mg ii h or k line exhibits a central reversal at the flare ribbons but turns to pure emission shortly after 1–4 minutes. Correspondingly, the C ii line also shows a central reversal but in a smaller region. However, for the Si iv line, the central reversal is only found in the X-class flare. As usual, the central reversal of these lines can be caused by the opacity effect. This implies that, in addition to the optically thick lines (C ii and Mg ii lines), the Si iv line can become optically thick in a strong flare, which is likely related to the nonthermal electron beam heating.
{"title":"Spectral Features of the Solar Transition Region and Chromospheric Lines at Flare Ribbons Observed with IRIS","authors":"L. F. Wang, Y. Li, Q. Li, X. Cheng, M. D. Ding","doi":"10.3847/1538-4365/acf127","DOIUrl":"https://doi.org/10.3847/1538-4365/acf127","url":null,"abstract":"Abstract We report on the spectral features of the Si iv λ 1402.77, C ii λ 1334.53, and Mg ii h or k lines, formed in the layers from the transition region to the chromosphere, in three two-ribbon flares (with X, M, and C class) observed with IRIS. All three lines show significant redshifts within the main flare ribbons, which mainly originate from the chromospheric condensation during the flares. The average redshift velocities of the Si iv line within the main ribbons are 56.6, 25.6, and 10.5 km s −1 for the X-, M-, and C-class flares, respectively, which show a decreasing tendency with the flare class. The C ii and Mg ii lines show a similar tendency but with smaller velocities compared to the Si iv line. Additionally, the Mg ii h or k line shows a blue-wing enhancement in the three flares, in particular at the flare ribbon fronts, which is supposed to be caused by an upflow in the upper chromosphere due to the heating of the atmosphere. Moreover, the Mg ii h or k line exhibits a central reversal at the flare ribbons but turns to pure emission shortly after 1–4 minutes. Correspondingly, the C ii line also shows a central reversal but in a smaller region. However, for the Si iv line, the central reversal is only found in the X-class flare. As usual, the central reversal of these lines can be caused by the opacity effect. This implies that, in addition to the optically thick lines (C ii and Mg ii lines), the Si iv line can become optically thick in a strong flare, which is likely related to the nonthermal electron beam heating.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135568237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Abstract For bright transients such as gamma-ray bursts (GRBs), the Ultra-Violet/Optical Telescope (UVOT) operates under event mode at early phases, which records incident positions and the arrival time for each photon. The event file is able to be screened into many exposures to study the early light curve of GRBs with a high time resolution, including the rapid brightening of the UV/optical emission in particular. Such a goal, however, is hampered for some extremely bright GRBs by the saturation in UVOT event images. For moderately saturated UVOT sources, in this work we further develop the method proposed in Jin et al. to recover their photometries. The basic idea is to assume a stable point-spread function of UVOT images, for which the counts in the core region (i.e., an aperture of a radius of 5″) and the wing region (i.e., an annulus ranging from 15″–25″) should be constant, and the intrinsic flux can be reliably inferred with data in the ring. We demonstrate that in a given band, a tight correlation does hold among the background-removed count rates in the core and the wing. With the new method, the bright limit of measuring range for UVOT V and B bands increases by ∼1.7 mag, while only by ∼0.7 mag for the U band due to the lack of bright calibration sources. Systematic uncertainties are ∼0.2 mag for the V , B , and U bands.
{"title":"A Method to Measure Photometries of Moderately Saturated UVOT Sources","authors":"Hao Zhou, Zhi-Ping Jin, Stefano Covino, Yi-Zhong Fan, Da-Ming Wei","doi":"10.3847/1538-4365/acf20a","DOIUrl":"https://doi.org/10.3847/1538-4365/acf20a","url":null,"abstract":"Abstract For bright transients such as gamma-ray bursts (GRBs), the Ultra-Violet/Optical Telescope (UVOT) operates under event mode at early phases, which records incident positions and the arrival time for each photon. The event file is able to be screened into many exposures to study the early light curve of GRBs with a high time resolution, including the rapid brightening of the UV/optical emission in particular. Such a goal, however, is hampered for some extremely bright GRBs by the saturation in UVOT event images. For moderately saturated UVOT sources, in this work we further develop the method proposed in Jin et al. to recover their photometries. The basic idea is to assume a stable point-spread function of UVOT images, for which the counts in the core region (i.e., an aperture of a radius of 5″) and the wing region (i.e., an annulus ranging from 15″–25″) should be constant, and the intrinsic flux can be reliably inferred with data in the ring. We demonstrate that in a given band, a tight correlation does hold among the background-removed count rates in the core and the wing. With the new method, the bright limit of measuring range for UVOT V and B bands increases by ∼1.7 mag, while only by ∼0.7 mag for the U band due to the lack of bright calibration sources. Systematic uncertainties are ∼0.2 mag for the V , B , and U bands.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135606720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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