Pub Date : 2024-08-22DOI: 10.3847/1538-4365/ad6261
YiMing He, Zhong Cao, Hui Deng, Feng Wang, Ying Mei, Lei Tan
Carbon stars play a crucial role in astronomical research and are significant for understanding stellar evolution, measuring cosmic distances, and studying galaxy kinematics. In recent years, identifying carbon stars using machine learning methods and traditional line-index methods has become a research hotspot, but there are still limitations regarding accuracy and automation. In this study, we propose to build a five-class model to identify carbon stars using spectral data from LAMOST DR9. The model achieved 99.45% precision and 91.21% recall on the carbon star testing set. We conducted independent tests using a sample of 1333 known carbon stars that were not used in the training and testing phases, and our model ultimately identified 1199 carbon stars. On this basis, we used this model to screen 11,226,252 spectra of LAMOST DR9 and identified 4383 carbon stars, including 1197 newly discovered carbon stars. To gain a more comprehensive understanding of the characteristics of the 4383 carbon stars obtained, further visual inspection of these spectra was performed to provide more detailed carbon star subtypes.
{"title":"Identification of Carbon Stars in LAMOST DR9 Based on Deep Learning","authors":"YiMing He, Zhong Cao, Hui Deng, Feng Wang, Ying Mei, Lei Tan","doi":"10.3847/1538-4365/ad6261","DOIUrl":"https://doi.org/10.3847/1538-4365/ad6261","url":null,"abstract":"Carbon stars play a crucial role in astronomical research and are significant for understanding stellar evolution, measuring cosmic distances, and studying galaxy kinematics. In recent years, identifying carbon stars using machine learning methods and traditional line-index methods has become a research hotspot, but there are still limitations regarding accuracy and automation. In this study, we propose to build a five-class model to identify carbon stars using spectral data from LAMOST DR9. The model achieved 99.45% precision and 91.21% recall on the carbon star testing set. We conducted independent tests using a sample of 1333 known carbon stars that were not used in the training and testing phases, and our model ultimately identified 1199 carbon stars. On this basis, we used this model to screen 11,226,252 spectra of LAMOST DR9 and identified 4383 carbon stars, including 1197 newly discovered carbon stars. To gain a more comprehensive understanding of the characteristics of the 4383 carbon stars obtained, further visual inspection of these spectra was performed to provide more detailed carbon star subtypes.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-22DOI: 10.3847/1538-4365/ad61e4
Jiawei Miao, Liangping Tu, Bin Jiang, Xiangru Li, Bo Qiu
In the past decade, various sky surveys with a wide range of wavelengths have been conducted, resulting in an explosive growth of survey data. There may be overlapping regions between different surveys, but the data quality and brightness are different. The translation of data quality between different surveys provides benefits for studying the properties of galaxies in specific regions that high-quality surveys have not yet covered. In this paper, we create a data set for analyzing the quality transformation of different surveys, AstroSR, using the galaxy images from overlapping regions from the Subaru/Hyper Suprime-Cam (HSC) and the Sloan Digital Sky Survey (SDSS). In addition, we use superresolution (SR) techniques to improve the quality of low-resolution images in the AstroSR and explore whether the proposed data set is suitable for SR. We try four representative models: EDSR, RCAN, ENLCN, and SRGAN. Finally, we compare the evaluation metrics and visual quality of the above methods. SR models trained with AstroSR successfully generate HSC-like images from SDSS images, which enhance the fine structure present in the SDSS images while retaining important morphological information and increasing the brightness and signal-to-noise. Improving the resolution of astronomical images by SR can improve the size and quality of the sky surveys. The data set proposed in this paper provides strong data support for the study of galaxy SR and opens up new research possibilities in astronomy. The data set is available online at https://github.com/jiaweimmiao/AstroSR.
在过去的十年中，人们开展了各种波长的巡天观测，巡天观测数据呈爆炸式增长。不同巡天之间可能存在重叠区域，但数据质量和亮度却各不相同。不同巡天观测之间数据质量的转换，有利于研究高质量巡天观测尚未覆盖的特定区域的星系特性。在本文中，我们利用来自Subaru/Hyper Suprime-Cam（HSC）和Sloan Digital Sky Survey（SDSS）重叠区域的星系图像，创建了一个用于分析不同巡天质量转换的数据集AstroSR。此外，我们还使用超分辨率（SR）技术来提高 AstroSR 中低分辨率图像的质量，并探索所提议的数据集是否适合 SR。我们尝试了四种具有代表性的模型：EDSR、RCAN、ENLCN 和 SRGAN。最后，我们比较了上述方法的评价指标和视觉质量。使用 AstroSR 训练的 SR 模型成功地从 SDSS 图像生成了类似 HSC 的图像，在保留重要形态信息、提高亮度和信噪比的同时，增强了 SDSS 图像中存在的精细结构。利用 SR 提高天文图像的分辨率可以改善巡天的规模和质量。本文提出的数据集为研究星系SR提供了有力的数据支持，为天文学研究开辟了新的可能性。该数据集可在 https://github.com/jiaweimmiao/AstroSR 在线查阅。
{"title":"AstroSR: A Data Set of Galaxy Images for Astronomical Superresolution Research","authors":"Jiawei Miao, Liangping Tu, Bin Jiang, Xiangru Li, Bo Qiu","doi":"10.3847/1538-4365/ad61e4","DOIUrl":"https://doi.org/10.3847/1538-4365/ad61e4","url":null,"abstract":"In the past decade, various sky surveys with a wide range of wavelengths have been conducted, resulting in an explosive growth of survey data. There may be overlapping regions between different surveys, but the data quality and brightness are different. The translation of data quality between different surveys provides benefits for studying the properties of galaxies in specific regions that high-quality surveys have not yet covered. In this paper, we create a data set for analyzing the quality transformation of different surveys, AstroSR, using the galaxy images from overlapping regions from the Subaru/Hyper Suprime-Cam (HSC) and the Sloan Digital Sky Survey (SDSS). In addition, we use superresolution (SR) techniques to improve the quality of low-resolution images in the AstroSR and explore whether the proposed data set is suitable for SR. We try four representative models: EDSR, RCAN, ENLCN, and SRGAN. Finally, we compare the evaluation metrics and visual quality of the above methods. SR models trained with AstroSR successfully generate HSC-like images from SDSS images, which enhance the fine structure present in the SDSS images while retaining important morphological information and increasing the brightness and signal-to-noise. Improving the resolution of astronomical images by SR can improve the size and quality of the sky surveys. The data set proposed in this paper provides strong data support for the study of galaxy SR and opens up new research possibilities in astronomy. The data set is available online at <ext-link ext-link-type=\"uri\" xlink:href=\"https://github.com/jiaweimmiao/AstroSR\" xlink:type=\"simple\">https://github.com/jiaweimmiao/AstroSR</ext-link>.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As an inaugural investigation under the X-ray Winds In Nearby-to-distant Galaxies (X-WING) program, we assembled a data set comprising 132 active galactic nuclei (AGNs) spanning redshifts z ∼ 0–4 characterized by blueshifted absorption lines indicative of X-ray winds. Through an exhaustive review of previous research, we compiled the outflow parameters for 583 X-ray winds, encompassing key attributes such as outflow velocities (Vout), ionization parameters (ξ), and hydrogen column densities. By leveraging the parameters Vout and ξ, we systematically categorized the winds into three distinct groups: ultrafast outflows (UFOs), low-ionization parameter (low-IP) UFOs, and warm absorbers (WAs). Strikingly, a discernible absence of linear correlations in the outflow parameters, coupled with distributions approaching instrumental detection limits, was observed. Another notable finding was the identification of a velocity gap around Vout ∼ 10,000 km s−1. This gap was particularly evident in the winds detected via absorption lines within the ≲2 keV band, indicating disparate origins for low-IP UFOs and WAs. In cases involving Fe xxv/Fe xxvi lines, where the gap might be attributed to potential confusion between emission/absorption lines and the Fe K-edge, the possibility of UFOs and galactic-scale WAs being disconnected is considered. An examination of the outflow and dust sublimation radii revealed a distinction: UFOs appear to consist of dust-free material, whereas WAs likely comprise dusty gas. From 2024, the X-Ray Imaging and Spectroscopy Mission is poised to alleviate observational biases, providing insights into the authenticity of the identified gap, a pivotal question in comprehending AGN feedback from UFOs.
作为 "近距离到远距离星系中的 X 射线风（X-WING）"计划的首次调查，我们收集了一个数据集，其中包括 132 个活动星系核（AGN），其红移 z ∼ 0-4，其特征是蓝移吸收线表明存在 X 射线风。通过对以往研究的详尽回顾，我们汇编了 583 个 X 射线风的外流参数，包括外流速度（Vout）、电离参数（ξ）和氢柱密度等关键属性。通过利用 Vout 和 ξ 参数，我们将这些风系统地分为三类：超快外流风（UFO）、低电离参数 UFO 和暖吸收风（WAs）。令人震惊的是，外流参数中明显缺乏线性相关关系，而且其分布接近仪器探测极限。另一个值得注意的发现是在 Vout ∼ 10,000 km s-1 附近发现了一个速度差距。这种差距在通过≲2 keV波段内的吸收线探测到的风中尤为明显，表明低IP UFO和WA的起源不同。在涉及铁 xxv/Fe xxvi 线的情况下，差距可能是由于发射线/吸收线和铁 K 边之间的潜在混淆造成的，因此考虑了 UFO 和银河尺度 WAs 互不关联的可能性。对流出半径和尘埃升华半径的研究揭示了两者之间的区别：UFO似乎由无尘物质组成，而WA则可能由含尘气体组成。从 2024 年起，X 射线成像和光谱任务将缓解观测偏差，提供对已发现缺口真实性的见解，这是理解 UFO AGN 反馈的一个关键问题。
{"title":"X-Ray Winds in Nearby-to-distant Galaxies (X-WING). I. Legacy Surveys of Galaxies with Ultrafast Outflows and Warm Absorbers in z ∼ 0–4","authors":"Satoshi Yamada, Taiki Kawamuro, Misaki Mizumoto, Claudio Ricci, Shoji Ogawa, Hirofumi Noda, Yoshihiro Ueda, Teruaki Enoto, Mitsuru Kokubo, Takeo Minezaki, Hiroaki Sameshima, Takashi Horiuchi, Shoichiro Mizukoshi","doi":"10.3847/1538-4365/ad5961","DOIUrl":"https://doi.org/10.3847/1538-4365/ad5961","url":null,"abstract":"As an inaugural investigation under the X-ray Winds In Nearby-to-distant Galaxies (X-WING) program, we assembled a data set comprising 132 active galactic nuclei (AGNs) spanning redshifts <italic toggle=\"yes\">z</italic> ∼ 0–4 characterized by blueshifted absorption lines indicative of X-ray winds. Through an exhaustive review of previous research, we compiled the outflow parameters for 583 X-ray winds, encompassing key attributes such as outflow velocities (<italic toggle=\"yes\">V</italic>\u0000<sub>out</sub>), ionization parameters (<italic toggle=\"yes\">ξ</italic>), and hydrogen column densities. By leveraging the parameters <italic toggle=\"yes\">V</italic>\u0000<sub>out</sub> and <italic toggle=\"yes\">ξ</italic>, we systematically categorized the winds into three distinct groups: ultrafast outflows (UFOs), low-ionization parameter (low-IP) UFOs, and warm absorbers (WAs). Strikingly, a discernible absence of linear correlations in the outflow parameters, coupled with distributions approaching instrumental detection limits, was observed. Another notable finding was the identification of a velocity gap around <italic toggle=\"yes\">V</italic>\u0000<sub>out</sub> ∼ 10,000 km s<sup>−1</sup>. This gap was particularly evident in the winds detected via absorption lines within the ≲2 keV band, indicating disparate origins for low-IP UFOs and WAs. In cases involving Fe <sc>xxv</sc>/Fe <sc>xxvi</sc> lines, where the gap might be attributed to potential confusion between emission/absorption lines and the Fe K-edge, the possibility of UFOs and galactic-scale WAs being disconnected is considered. An examination of the outflow and dust sublimation radii revealed a distinction: UFOs appear to consist of dust-free material, whereas WAs likely comprise dusty gas. From 2024, the X-Ray Imaging and Spectroscopy Mission is poised to alleviate observational biases, providing insights into the authenticity of the identified gap, a pivotal question in comprehending AGN feedback from UFOs.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a comprehensive study of ultraluminous infrared galaxies (ULIRGs), leveraging data from the Infrared Astronomical Satellite Faint Source Catalogue and the spectroscopic catalog in the Sloan Digital Sky Survey Data Release 16. Our meticulous crossmatching technique significantly enhances the reliability of ULIRG identification, resulting in the identification of 283 reliable ULIRGs, including 102 new detections, while discarding 120 previously reported false sources. Covering a redshift range of z = 0.018–0.996, with a median redshift of z¯=0.259, our uniform sample reveals apparent interaction features in approximately 40% of ULIRGs, increasing to 92% for those with z < 0.1. Through optical spectra analysis, it is indicated that over 58% of ULIRGs host an active galactic nucleus (AGN), which is twice as high as detections based solely on infrared colors. Moreover, a pronounced excess of radio emissions associated with AGN activity results in a steeper radio–far-infrared correlation. Notably, Type I ULIRGs exhibit properties similar to those of narrow-line Seyfert 1 galaxies, with an elevated incidence rate of Mg ii broad absorption lines (16.7%), surpassing that of typical optically selected quasars by over tenfold, consistent with current evolutionary models. We anticipate that forthcoming telescopes such as the China Space Station Telescope and Leighton Chajnantor Telescope will provide deeper insights into ULIRG morphology, dust distribution, molecular gas, and AGN activity.
{"title":"A Comparative Study of Ultraluminous Infrared Galaxies in the IRAS and SDSS Surveys","authors":"Shaohua Zhang, Zhijian Luo, Xiheng Shi, Chenggang Shu, Hubing Xiao, Hongyan Zhou","doi":"10.3847/1538-4365/ad5d75","DOIUrl":"https://doi.org/10.3847/1538-4365/ad5d75","url":null,"abstract":"We present a comprehensive study of ultraluminous infrared galaxies (ULIRGs), leveraging data from the Infrared Astronomical Satellite Faint Source Catalogue and the spectroscopic catalog in the Sloan Digital Sky Survey Data Release 16. Our meticulous crossmatching technique significantly enhances the reliability of ULIRG identification, resulting in the identification of 283 reliable ULIRGs, including 102 new detections, while discarding 120 previously reported false sources. Covering a redshift range of <italic toggle=\"yes\">z</italic> = 0.018–0.996, with a median redshift of <inline-formula>\u0000<tex-math>\u0000<?CDATA $bar{z}=0.259$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mover accent=\"true\"><mml:mrow><mml:mi>z</mml:mi></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover><mml:mo>=</mml:mo><mml:mn>0.259</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"apjsad5d75ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, our uniform sample reveals apparent interaction features in approximately 40% of ULIRGs, increasing to 92% for those with <italic toggle=\"yes\">z</italic> < 0.1. Through optical spectra analysis, it is indicated that over 58% of ULIRGs host an active galactic nucleus (AGN), which is twice as high as detections based solely on infrared colors. Moreover, a pronounced excess of radio emissions associated with AGN activity results in a steeper radio–far-infrared correlation. Notably, Type I ULIRGs exhibit properties similar to those of narrow-line Seyfert 1 galaxies, with an elevated incidence rate of Mg <sc>ii</sc> broad absorption lines (16.7%), surpassing that of typical optically selected quasars by over tenfold, consistent with current evolutionary models. We anticipate that forthcoming telescopes such as the China Space Station Telescope and Leighton Chajnantor Telescope will provide deeper insights into ULIRG morphology, dust distribution, molecular gas, and AGN activity.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In our previous study, we introduced a machine learning technique, namely Cosmic Microwave Background Foreground Subtraction with Convolutional Neural Networks (CMBFSCNN), for the removal of foreground contamination in cosmic microwave background (CMB) polarization data. This method was successfully employed on actual observational data from the Planck mission. In this study, we extend our investigation by considering the CMB lensing effect in simulated data and utilizing the CMBFSCNN approach to recover the CMB lensing B-mode power spectrum from multifrequency observational maps. Our method is first applied to simulated data with the performance of the CMB-S4 experiment. We achieve reliable recovery of the noisy CMB Q (or U) maps with a mean absolute difference of 0.016 ± 0.008 μK (or 0.021 ± 0.002 μK) for the CMB-S4 experiment. To address the residual instrumental noise in the foreground-cleaned map, we employ a “half-split maps” approach, where the entire data set is divided into two segments sharing the same sky signal but having uncorrelated noise. Using cross-correlation techniques between two recovered half-split maps, we effectively reduce instrumental noise effects at the power spectrum level. As a result, we achieve precise recovery of the CMB EE and lensing B-mode power spectra. Furthermore, we also extend our pipeline to full-sky simulated data with the performance of the LiteBIRD experiment. As expected, various foregrounds are cleanly removed from the foregrounds contamination observational maps, and recovered EE and lensing B-mode power spectra exhibit excellent agreement with the true results. Finally, we discuss the dependency of our method on the foreground models.
在之前的研究中，我们介绍了一种机器学习技术，即卷积神经网络宇宙微波背景前景减法（CMBFSCNN），用于去除宇宙微波背景（CMB）极化数据中的前景污染。该方法已成功应用于普朗克任务的实际观测数据。在本研究中，我们扩展了研究范围，考虑了模拟数据中的 CMB 透镜效应，并利用 CMBFSCNN 方法从多频观测图中恢复 CMB 透镜 B 模式功率谱。我们的方法首先应用于具有 CMB-S4 实验性能的模拟数据。我们可靠地恢复了有噪声的 CMB Q（或 U）图，CMB-S4 实验的平均绝对差值为 0.016 ± 0.008 μK（或 0.021 ± 0.002 μK）。为了解决前景净化图中的残余仪器噪声问题，我们采用了 "半分割图 "方法，即将整个数据集划分为共享相同天空信号但噪声不相关的两个区段。利用两个恢复的半分割图之间的交叉相关技术，我们可以有效地减少功率谱级的仪器噪声影响。因此，我们实现了对 CMB EE 和透镜 B 模式功率谱的精确恢复。此外，我们还利用 LiteBIRD 实验的性能，将我们的管道扩展到全天空模拟数据。不出所料，各种前景都被从前景污染观测图中清除了，恢复的 EE 和 Lensing B 模式功率谱与真实结果呈现出极好的一致性。最后，我们讨论了我们的方法对前景模型的依赖性。
{"title":"CMBFSCNN: Cosmic Microwave Background Polarization Foreground Subtraction with a Convolutional Neural Network","authors":"Ye-Peng Yan, Si-Yu Li, Guo-Jian Wang, Zirui Zhang, Jun-Qing Xia","doi":"10.3847/1538-4365/ad5c66","DOIUrl":"https://doi.org/10.3847/1538-4365/ad5c66","url":null,"abstract":"In our previous study, we introduced a machine learning technique, namely Cosmic Microwave Background Foreground Subtraction with Convolutional Neural Networks (<monospace>CMBFSCNN</monospace>), for the removal of foreground contamination in cosmic microwave background (CMB) polarization data. This method was successfully employed on actual observational data from the Planck mission. In this study, we extend our investigation by considering the CMB lensing effect in simulated data and utilizing the <monospace>CMBFSCNN</monospace> approach to recover the CMB lensing B-mode power spectrum from multifrequency observational maps. Our method is first applied to simulated data with the performance of the CMB-S4 experiment. We achieve reliable recovery of the noisy CMB <italic toggle=\"yes\">Q</italic> (or <italic toggle=\"yes\">U</italic>) maps with a mean absolute difference of 0.016 ± 0.008 <italic toggle=\"yes\">μ</italic>K (or 0.021 ± 0.002 <italic toggle=\"yes\">μ</italic>K) for the CMB-S4 experiment. To address the residual instrumental noise in the foreground-cleaned map, we employ a “half-split maps” approach, where the entire data set is divided into two segments sharing the same sky signal but having uncorrelated noise. Using cross-correlation techniques between two recovered half-split maps, we effectively reduce instrumental noise effects at the power spectrum level. As a result, we achieve precise recovery of the CMB EE and lensing B-mode power spectra. Furthermore, we also extend our pipeline to full-sky simulated data with the performance of the LiteBIRD experiment. As expected, various foregrounds are cleanly removed from the foregrounds contamination observational maps, and recovered EE and lensing B-mode power spectra exhibit excellent agreement with the true results. Finally, we discuss the dependency of our method on the foreground models.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-12DOI: 10.3847/1538-4365/ad5bde
Monica Seglar-Arroyo, Halim Ashkar, Mathieu de Bony de Lavergne, Fabian Schüssler
Time-domain astrophysics has leaped forward with the direct discovery of gravitational waves and the emergence of new generation instruments for multimessenger studies. The capacity of the multimessenger multiwavelength community to effectively pursue follow-up observations is hindered by the suboptimal localization of numerous transient events and the escalating volume of alerts. Thus, we have developed an effective tool to overcome the observational and technical hurdles inherent in the emerging field of multimessenger astrophysics. We present tilepy, a Python package for the automatic scheduling of follow-up observations of poorly localized transient events. It is ideally suited to tackle the challenge of complex follow-up in mid- and small-field-of-view telescope campaigns, with or without human intervention. We demonstrate the capabilities of tilepy in the realm of multiobservatory, multiwavelength campaigns, to cover the localization uncertainty region of various events ultimately aiming at pinpointing the source of the multimessenger emission. The tilepy code is publicly available on GitHub and is sufficiently flexible to be employed either automatically or in a customized manner, tailored to collaboration and individual requirements. tilepy is also accessible via a public API and through the Astro-COLIBRI platform.
{"title":"Cross Observatory Coordination with tilepy: A Novel Tool for Observations of Multimessenger Transient Events","authors":"Monica Seglar-Arroyo, Halim Ashkar, Mathieu de Bony de Lavergne, Fabian Schüssler","doi":"10.3847/1538-4365/ad5bde","DOIUrl":"https://doi.org/10.3847/1538-4365/ad5bde","url":null,"abstract":"Time-domain astrophysics has leaped forward with the direct discovery of gravitational waves and the emergence of new generation instruments for multimessenger studies. The capacity of the multimessenger multiwavelength community to effectively pursue follow-up observations is hindered by the suboptimal localization of numerous transient events and the escalating volume of alerts. Thus, we have developed an effective tool to overcome the observational and technical hurdles inherent in the emerging field of multimessenger astrophysics. We present <monospace>tilepy</monospace>, a Python package for the automatic scheduling of follow-up observations of poorly localized transient events. It is ideally suited to tackle the challenge of complex follow-up in mid- and small-field-of-view telescope campaigns, with or without human intervention. We demonstrate the capabilities of <monospace>tilepy</monospace> in the realm of multiobservatory, multiwavelength campaigns, to cover the localization uncertainty region of various events ultimately aiming at pinpointing the source of the multimessenger emission. The <monospace>tilepy</monospace> code is publicly available on GitHub and is sufficiently flexible to be employed either automatically or in a customized manner, tailored to collaboration and individual requirements. <monospace>tilepy</monospace> is also accessible via a public API and through the Astro-COLIBRI platform.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-11DOI: 10.3847/1538-4365/ad55c9
J. S. Gallagher, R. Kotulla, L. Laufman, E. Geist, S. Aalto, N. Falstad, S. König, J. Krause, G. C. Privon, C. Wethers, A. Evans and M. Gorski
Zw 049.057 is a moderate-mass, dusty, early-type galaxy that hosts a powerful compact obscured nucleus (CON, LFIR,CON ≥ 1011L⊙). The resolution of the Hubble Space Telescope enabled measurements of the stellar light distribution and characterization of dust features. Zw 049.057 is inclined with a prominent three-zone disk; the R ≈ 1 kpc star-forming inner dusty disk contains molecular gas, a main disk with less dust and an older stellar population, and a newly detected outer stellar region at R > 6 kpc with circular isophotes. Previously unknown polar dust lanes are signatures of a past minor merger that could have warped the outer disk to near face-on. Dust transmission measurements provide lower limit gas mass estimates for dust features. An extended region with moderate optical depth and M ≥ 2 × 108M⊙ obscures the central 2 kpc. Optical spectra show strong interstellar Na D absorption with a constant velocity across the main disk, likely arising in this extraplanar medium. Opacity measurements of the two linear dust features, pillars, give a total mass of ≥106M⊙, flow rates of ≥2 M⊙ yr−1, and few Myr flow times. Dust pillars are associated with the CON and are visible signs of its role in driving large-scale feedback. Our assessments of feedback processes suggest gas recycling sustains the CON. However, radiation pressure driven mass loss and efficient star formation must be avoided for the active galactic nucleus to retain sufficient gas over its lifespan to produce substantial mass growth of the central black hole.
Zw 049.057 是一个中等质量、尘埃较多的早期型星系，其中有一个强大的紧密遮挡核（CON, LFIR,CON ≥ 1011L⊙）。利用哈勃太空望远镜的分辨率，可以测量恒星光分布和尘埃特征。Zw 049.057呈倾斜状，有一个突出的三区盘；R≈1 kpc的恒星形成内尘埃盘包含分子气体，主盘尘埃较少，恒星群较老，在R>6 kpc处新探测到一个外恒星区，有圆形等距线。以前未知的极地尘埃通道是过去一次小规模合并的标志，可能将外盘扭曲到接近正面。尘埃透射测量为尘埃特征提供了下限气体质量估计值。一个具有中等光学深度、M ≥ 2 × 108M⊙的扩展区域遮挡了中心的 2 kpc。光学光谱显示，主圆盘上的星际 Na D 吸收很强，速度恒定，很可能是由这种星外介质引起的。对两个线性尘柱特征的不透明度测量结果表明，尘柱的总质量≥106M⊙，流速≥2 M⊙yr-1，流动时间为几Myr。尘柱与CON有关，是其驱动大规模反馈的明显标志。我们对反馈过程的评估表明，气体循环维持着CON。然而，要使活动星系核在其生命周期内保留足够的气体，使中心黑洞的质量大幅增长，就必须避免辐射压力驱动的质量损失和有效的恒星形成。
{"title":"An Imaging and Spectroscopic Exploration of the Dusty Compact Obscured Nucleus Galaxy Zw 049.057*","authors":"J. S. Gallagher, R. Kotulla, L. Laufman, E. Geist, S. Aalto, N. Falstad, S. König, J. Krause, G. C. Privon, C. Wethers, A. Evans and M. Gorski","doi":"10.3847/1538-4365/ad55c9","DOIUrl":"https://doi.org/10.3847/1538-4365/ad55c9","url":null,"abstract":"Zw 049.057 is a moderate-mass, dusty, early-type galaxy that hosts a powerful compact obscured nucleus (CON, LFIR,CON ≥ 1011L⊙). The resolution of the Hubble Space Telescope enabled measurements of the stellar light distribution and characterization of dust features. Zw 049.057 is inclined with a prominent three-zone disk; the R ≈ 1 kpc star-forming inner dusty disk contains molecular gas, a main disk with less dust and an older stellar population, and a newly detected outer stellar region at R > 6 kpc with circular isophotes. Previously unknown polar dust lanes are signatures of a past minor merger that could have warped the outer disk to near face-on. Dust transmission measurements provide lower limit gas mass estimates for dust features. An extended region with moderate optical depth and M ≥ 2 × 108M⊙ obscures the central 2 kpc. Optical spectra show strong interstellar Na D absorption with a constant velocity across the main disk, likely arising in this extraplanar medium. Opacity measurements of the two linear dust features, pillars, give a total mass of ≥106M⊙, flow rates of ≥2 M⊙ yr−1, and few Myr flow times. Dust pillars are associated with the CON and are visible signs of its role in driving large-scale feedback. Our assessments of feedback processes suggest gas recycling sustains the CON. However, radiation pressure driven mass loss and efficient star formation must be avoided for the active galactic nucleus to retain sufficient gas over its lifespan to produce substantial mass growth of the central black hole.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-11DOI: 10.3847/1538-4365/ad5b61
Zhongding Cheng, Xiaoming Kong, Tianmin Wu, Aina Zhang, Bowen Liu, Yude Bu, Zhenxin Lei, Yatao Zhang, Zhenping Yi and Meng Liu
This paper presents a robust neural network approach for identifying hot subdwarfs. Our method leveraged the Squeeze-and-Excitation Residual Network to extract abstract features, which were combined with experience features to create hybrid features. These hybrid features were then classified using a support vector machine. To enhance accuracy, we employed a two-stage procedure. In the first stage, a binary classification model was constructed to distinguish hot subdwarfs, achieving a precision of 98.55% on the test set. In the second stage, a four-class classification model was employed to further refine the candidates, achieving a precision of 91.75% on the test set. Using the binary classification model, we classified 333,534 spectra from LAMOST DR8, resulting in a catalog of 3086 hot subdwarf candidates. Subsequently, the four-class classification model was applied to filter these candidates further. When applying thresholds of 0.5 and 0.9, we identified 2132 and 1247 candidates, respectively. Among these candidates, we visually inspected their spectra and identified 58 and 30 new hot subdwarfs, respectively, resulting in a precision of 82.04% and 88.21% for these discoveries. Furthermore, we evaluated the 3086 candidates obtained in the first stage and identified 168 new hot subdwarfs, achieving an overall precision of 62.54%. Lastly, we trained a Squeeze-and-Excitation regression model with mean absolute error values of 3009 K for Teff, 0.20 dex for log g, and 0.42 dex for log(nHe/nH). Using this model, we predicted the atmospheric parameters of these 168 newly discovered hot subdwarfs.
{"title":"Se-ResNet+SVM Model: An Effective Method of Searching for Hot Subdwarfs from LAMOST","authors":"Zhongding Cheng, Xiaoming Kong, Tianmin Wu, Aina Zhang, Bowen Liu, Yude Bu, Zhenxin Lei, Yatao Zhang, Zhenping Yi and Meng Liu","doi":"10.3847/1538-4365/ad5b61","DOIUrl":"https://doi.org/10.3847/1538-4365/ad5b61","url":null,"abstract":"This paper presents a robust neural network approach for identifying hot subdwarfs. Our method leveraged the Squeeze-and-Excitation Residual Network to extract abstract features, which were combined with experience features to create hybrid features. These hybrid features were then classified using a support vector machine. To enhance accuracy, we employed a two-stage procedure. In the first stage, a binary classification model was constructed to distinguish hot subdwarfs, achieving a precision of 98.55% on the test set. In the second stage, a four-class classification model was employed to further refine the candidates, achieving a precision of 91.75% on the test set. Using the binary classification model, we classified 333,534 spectra from LAMOST DR8, resulting in a catalog of 3086 hot subdwarf candidates. Subsequently, the four-class classification model was applied to filter these candidates further. When applying thresholds of 0.5 and 0.9, we identified 2132 and 1247 candidates, respectively. Among these candidates, we visually inspected their spectra and identified 58 and 30 new hot subdwarfs, respectively, resulting in a precision of 82.04% and 88.21% for these discoveries. Furthermore, we evaluated the 3086 candidates obtained in the first stage and identified 168 new hot subdwarfs, achieving an overall precision of 62.54%. Lastly, we trained a Squeeze-and-Excitation regression model with mean absolute error values of 3009 K for Teff, 0.20 dex for log g, and 0.42 dex for log(nHe/nH). Using this model, we predicted the atmospheric parameters of these 168 newly discovered hot subdwarfs.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.3847/1538-4365/ad5af3
Karim Shariff
The Padé code has been developed to treat hydrodynamic turbulence in protoplanetary disks. It solves the compressible equations of motion in cylindrical coordinates. Derivatives are computed using nondiffusive and conservative fourth-order Padé differencing, which has higher resolving power compared to both dissipative shock-capturing schemes used in most astrophysics codes, as well as nondiffusive central finite-difference schemes of the same order. The fourth-order Runge–Kutta method is used for time stepping. A previously reported error-corrected Fargo approach is used to reduce the time step constraint imposed by rapid Keplerian advection. Artificial bulk viscosity is used when shock capturing is required. Tests for correctness and scaling with respect to the number of processors are presented. Finally, efforts to improve efficiency and accuracy are suggested.
{"title":"p adé: A Code for Protoplanetary Disk Turbulence Based on Padé Differencing","authors":"Karim Shariff","doi":"10.3847/1538-4365/ad5af3","DOIUrl":"https://doi.org/10.3847/1538-4365/ad5af3","url":null,"abstract":"The Padé code has been developed to treat hydrodynamic turbulence in protoplanetary disks. It solves the compressible equations of motion in cylindrical coordinates. Derivatives are computed using nondiffusive and conservative fourth-order Padé differencing, which has higher resolving power compared to both dissipative shock-capturing schemes used in most astrophysics codes, as well as nondiffusive central finite-difference schemes of the same order. The fourth-order Runge–Kutta method is used for time stepping. A previously reported error-corrected Fargo approach is used to reduce the time step constraint imposed by rapid Keplerian advection. Artificial bulk viscosity is used when shock capturing is required. Tests for correctness and scaling with respect to the number of processors are presented. Finally, efforts to improve efficiency and accuracy are suggested.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.3847/1538-4365/ad582d
M. Di Criscienzo, S. Leccia, V. Braga, I. Musella, G. Bono, M. Dall’Ora, G. Fiorentino, M. Marconi, R. Molinaro, V. Ripepi, L. Girardi, A. Mazzi, G. Pastorelli, M. Trabucchi, N. Matsunaga, M. Monelli, A. Saha, K. A. Vivas and R. Zanmar Sanchez
This work is part of VESTALE, a project initiated within the Legacy Survey of Space and Time (LSST) Cadence Strategy Optimization Process. Its goal is to explore the potential of Rubin-LSST observations aimed at the Galactic bulge (henceforth just “Bulge”) for studying RR Lyrae (RRL) stars. Observation and analysis of RRL stars in the Bulge are crucial for tracing the old population of the central part of our Galaxy and reconstructing its formation. Based on observations conducted with CTIO/DECam by Saha et al. toward Baade’s window, our simulations demonstrate that early Rubin-LSST observations will enable the recovery of RRL light curves (LCs) at Galactic center distances with sufficient precision. This will allow us to utilize theoretical relations from Marconi et al. to determine their distances and/or metallicity, following the REDIME algorithm introduced in Bono et al. We show how reddening and crowding affect our simulations and highlight the importance of considering these effects when deriving pulsation parameters (luminosity amplitudes, mean magnitudes) based on the LCs, especially if the goal is to explore the opposite side of the Bulge through the observation of its RRL. The simulations discussed in this investigation were conducted to support the Survey Cadence Optimization Committee’s decision to observe this important sky region since it has only recently been decided to include part of the Bulge as a target within the LSST main survey.
{"title":"Light-curve Recovery with Rubin-LSST. II. Unveiling the Darkness of the Galactic Bulge (VESTALE) with RR Lyrae","authors":"M. Di Criscienzo, S. Leccia, V. Braga, I. Musella, G. Bono, M. Dall’Ora, G. Fiorentino, M. Marconi, R. Molinaro, V. Ripepi, L. Girardi, A. Mazzi, G. Pastorelli, M. Trabucchi, N. Matsunaga, M. Monelli, A. Saha, K. A. Vivas and R. Zanmar Sanchez","doi":"10.3847/1538-4365/ad582d","DOIUrl":"https://doi.org/10.3847/1538-4365/ad582d","url":null,"abstract":"This work is part of VESTALE, a project initiated within the Legacy Survey of Space and Time (LSST) Cadence Strategy Optimization Process. Its goal is to explore the potential of Rubin-LSST observations aimed at the Galactic bulge (henceforth just “Bulge”) for studying RR Lyrae (RRL) stars. Observation and analysis of RRL stars in the Bulge are crucial for tracing the old population of the central part of our Galaxy and reconstructing its formation. Based on observations conducted with CTIO/DECam by Saha et al. toward Baade’s window, our simulations demonstrate that early Rubin-LSST observations will enable the recovery of RRL light curves (LCs) at Galactic center distances with sufficient precision. This will allow us to utilize theoretical relations from Marconi et al. to determine their distances and/or metallicity, following the REDIME algorithm introduced in Bono et al. We show how reddening and crowding affect our simulations and highlight the importance of considering these effects when deriving pulsation parameters (luminosity amplitudes, mean magnitudes) based on the LCs, especially if the goal is to explore the opposite side of the Bulge through the observation of its RRL. The simulations discussed in this investigation were conducted to support the Survey Cadence Optimization Committee’s decision to observe this important sky region since it has only recently been decided to include part of the Bulge as a target within the LSST main survey.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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