J. L. B. Line, C. M. Trott, J. H. Cook, B. Greig, N. Barry, C. H. Jordan
We present the first of two papers dedicated to verifying the Australian Epoch of Reionisation pipeline (AusEoRPipe) through simulation. The AusEoRPipe aims to disentangle 21-cm radiation emitted by gas surrounding the very first stars from contaminating foreground astrophysical sources, and has been in development for close to a decade. In this paper, we build an accurate 21-cm sky model that can be used by the WODEN simulation software to create visibilities containing a predictable 21-cm signal. We verify that the power spectrum estimator CHIPS can recover this signal in the absence of foregrounds. We also investigate how measurements in Fourier-space are correlated, and how their gridded density affects the power spectrum. We measure and fit for this effect using Gaussian-noise simulations of the MWA phase I layout. We find a gridding density correction factor of 2.651 appropriate for integrations equal to or greater than 30 minutes of data, which contain observations with multiple primary beam pointings and LSTs. Paper II of this series will use the results of this paper to test the AusEoRPipe in the presence of foregrounds and instrumental effects.
{"title":"Verifying the Australian MWA EoR pipeline I: 21-cm sky model and correlated measurement density","authors":"J. L. B. Line, C. M. Trott, J. H. Cook, B. Greig, N. Barry, C. H. Jordan","doi":"10.1017/pasa.2024.31","DOIUrl":"https://doi.org/10.1017/pasa.2024.31","url":null,"abstract":"We present the first of two papers dedicated to verifying the Australian Epoch of Reionisation pipeline (<jats:monospace>AusEoRPipe</jats:monospace>) through simulation. The <jats:monospace>AusEoRPipe</jats:monospace> aims to disentangle 21-cm radiation emitted by gas surrounding the very first stars from contaminating foreground astrophysical sources, and has been in development for close to a decade. In this paper, we build an accurate 21-cm sky model that can be used by the <jats:monospace>WODEN</jats:monospace> simulation software to create visibilities containing a predictable 21-cm signal. We verify that the power spectrum estimator <jats:monospace>CHIPS</jats:monospace> can recover this signal in the absence of foregrounds. We also investigate how measurements in Fourier-space are correlated, and how their gridded density affects the power spectrum. We measure and fit for this effect using Gaussian-noise simulations of the MWA phase I layout. We find a gridding density correction factor of 2.651 appropriate for integrations equal to or greater than 30 minutes of data, which contain observations with multiple primary beam pointings and LSTs. Paper II of this series will use the results of this paper to test the <jats:monospace>AusEoRPipe</jats:monospace> in the presence of foregrounds and instrumental effects.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"12 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140627895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aishwarya Selvaraj, Randall B Wayth, Cathryn M Trott, Gurashish Singh Bhatia
Exploration of the 21cm signal during the Cosmic Dawn and the Epoch of Reionisation (EoR) can unravel the mysteries of the early Universe when the first stars and galaxies were born and ionised, respectively. However, the 21cm signal is exceptionally weak, and thus, the detection amidst the bright foregrounds is extremely challenging. The MurchisonWidefield Array (MWA) aims to measure the brightness temperature fluctuations of neutral hydrogen from the early Universe. The MWA telescope observes the radio sky with a large Field of View (FoV) that causes the bright galaxies, especially near the horizon, to contaminate the measurements. These foregrounds contaminating the EoR datasets must be meticulously removed or treated to detect the signal successfully. The Central Redundant Array Mega-tile (CRAM) is a zenith-pointing new instrument, installed at the centre of the MWA Phase II southern hexagonal configuration, comprising of 64 dipoles in an 8 × 8 configuration with a FoV half the width of the MWA’s at every frequency under consideration. The primary objective of this new instrument is to mitigate the impact of bright radio sources near the field centre in accordance with the reduced primary beamshape and to reduce the contamination of foreground sources near the horizon with the reduced sidelobe response of the larger array configuration. In this paper, we introduce the new instrument to the community and present the system architecture and characteristics of the instrument. Using the first light observations, we determine the CRAM system temperature and system performance.
探索宇宙黎明期和电离纪元（EoR）的 21 厘米信号可以揭开早期宇宙的神秘面纱，当时第一批恒星和星系分别诞生和电离。然而，21 厘米信号非常微弱，因此在明亮前景中进行探测极具挑战性。默奇森宽视场阵列（MWA）旨在测量早期宇宙中性氢的亮度温度波动。MWA 望远镜观测射电天空时具有很大的视场（FoV），这会导致明亮的星系，尤其是地平线附近的星系，污染测量结果。这些污染 EoR 数据集的前景必须经过精心去除或处理，才能成功探测到信号。中央冗余阵列兆瓦（CRAM）是一个天顶指向型新仪器，安装在 MWA 第二阶段南六边形配置的中心，由 64 个偶极子组成，呈 8 × 8 配置，在所考虑的每个频率上，其视场角都是 MWA 宽度的一半。这一新仪器的主要目标是根据减小的主波束形状来减轻场中心附近明亮射电源的影响，并通过较大阵列配置的减小侧叶响应来减少地平线附近前景源的污染。在本文中，我们将向公众介绍这台新仪器，并介绍仪器的系统结构和特点。利用首照观测，我们确定了 CRAM 系统的温度和系统性能。
{"title":"System design and validation of Central Redundant Array Mega-tile (CRAM)","authors":"Aishwarya Selvaraj, Randall B Wayth, Cathryn M Trott, Gurashish Singh Bhatia","doi":"10.1017/pasa.2024.33","DOIUrl":"https://doi.org/10.1017/pasa.2024.33","url":null,"abstract":"Exploration of the 21cm signal during the Cosmic Dawn and the Epoch of Reionisation (EoR) can unravel the mysteries of the early Universe when the first stars and galaxies were born and ionised, respectively. However, the 21cm signal is exceptionally weak, and thus, the detection amidst the bright foregrounds is extremely challenging. The MurchisonWidefield Array (MWA) aims to measure the brightness temperature fluctuations of neutral hydrogen from the early Universe. The MWA telescope observes the radio sky with a large Field of View (FoV) that causes the bright galaxies, especially near the horizon, to contaminate the measurements. These foregrounds contaminating the EoR datasets must be meticulously removed or treated to detect the signal successfully. The Central Redundant Array Mega-tile (CRAM) is a zenith-pointing new instrument, installed at the centre of the MWA Phase II southern hexagonal configuration, comprising of 64 dipoles in an 8 × 8 configuration with a FoV half the width of the MWA’s at every frequency under consideration. The primary objective of this new instrument is to mitigate the impact of bright radio sources near the field centre in accordance with the reduced primary beamshape and to reduce the contamination of foreground sources near the horizon with the reduced sidelobe response of the larger array configuration. In this paper, we introduce the new instrument to the community and present the system architecture and characteristics of the instrument. Using the first light observations, we determine the CRAM system temperature and system performance.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"24 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140628654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Suk Yee Yong, K. E. Harborne, Caroline Foster, Robert Bassett, Gregory B. Poole, Mitchell Cavanagh
Since the turn of the century, astronomers have been exploiting the rich information afforded by combining stellar kinematic maps and imaging in an attempt to recover the intrinsic, three-dimensional (3D) shape of a galaxy. A common intrinsic shape recovery method relies on an expected monotonic relationship between the intrinsic misalignment of the kinematic and morphological axes and the triaxiality parameter. Recent studies have, however, cast doubt about underlying assumptions relating shape and intrinsic kinematic misalignment. In this work, we aim to recover the 3D shape of individual galaxies using their projected stellar kinematic and flux distributions using a supervised machine learning approach with mixture density network (MDN). Using a mock dataset of the EAGLE hydrodynamical cosmological simulation, we train the MDN model for a carefully selected set of common kinematic and photometric parameters. Compared to previous methods, we demonstrate potential improvements achieved with the MDN model to retrieve the 3D galaxy shape along with the uncertainties, especially for prolate and triaxial systems. We make specific recommendations for recovering galaxy intrinsic shapes relevant for current and future integral field spectroscopic galaxy surveys.
{"title":"Galaxy 3D Shape Recovery using Mixture Density Network","authors":"Suk Yee Yong, K. E. Harborne, Caroline Foster, Robert Bassett, Gregory B. Poole, Mitchell Cavanagh","doi":"10.1017/pasa.2024.32","DOIUrl":"https://doi.org/10.1017/pasa.2024.32","url":null,"abstract":"Since the turn of the century, astronomers have been exploiting the rich information afforded by combining stellar kinematic maps and imaging in an attempt to recover the intrinsic, three-dimensional (3D) shape of a galaxy. A common intrinsic shape recovery method relies on an expected monotonic relationship between the intrinsic misalignment of the kinematic and morphological axes and the triaxiality parameter. Recent studies have, however, cast doubt about underlying assumptions relating shape and intrinsic kinematic misalignment. In this work, we aim to recover the 3D shape of <jats:italic>individual</jats:italic> galaxies using their projected stellar kinematic and flux distributions using a supervised machine learning approach with mixture density network (MDN). Using a mock dataset of the EAGLE hydrodynamical cosmological simulation, we train the MDN model for a carefully selected set of common kinematic and photometric parameters. Compared to previous methods, we demonstrate potential improvements achieved with the MDN model to retrieve the 3D galaxy shape along with the uncertainties, especially for prolate and triaxial systems. We make specific recommendations for recovering galaxy intrinsic shapes relevant for current and future integral field spectroscopic galaxy surveys.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"36 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140627892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High-precision pulsar timing observations are limited in their accuracy by the jitter noise that appears in the arrival time of pulses. Therefore, it is important to systematically characterise the amplitude of the jitter noise and its variation with frequency. In this paper, we provide jitter measurements from low-frequency wideband observations of PSR J0437–4715 using data obtained as part of the Indian Pulsar Timing Array experiment. We were able to detect jitter in both the 300 - 500 MHz and 1260 - 1460 MHz observations of the upgraded Giant Metrewave Radio Telescope (uGMRT). The former is the first jitter measurement for this pulsar below 700 MHz, and the latter is in good agreement with results from previous studies. In addition, at 300 - 500 MHz, we investigated the frequency dependence of the jitter by calculating the jitter for each sub-banded arrival time of pulses. We found that the jitter amplitude increases with frequency. This trend is opposite as compared to previous studies, indicating that there is a turnover at intermediate frequencies. It will be possible to investigate this in more detail with uGMRT observations at 550 - 750 MHz and future high sensitive wideband observations from next generation telescopes, such as the Square Kilometre Array. We also explored the effect of jitter on the high precision dispersion measure (DM) measurements derived from short duration observations. We find that even though the DM precision will be better at lower frequencies due to the smaller amplitude of jitter noise, it will limit the DM precision for high signal-to-noise observations, which are of short durations. This limitation can be overcome by integrating for a long enough duration optimised for a given pulsar.
{"title":"Low-frequency pulse-jitter measurement with the uGMRT I : PSR J0437–4715","authors":"Tomonosuke Kikunaga, Shinnosuke Hisano, Neelam Dhanda Batra, Shantanu Desai, Bhal Chandra Joshi, Manjari Bagchi, T. Prabu, Keitaro Takahashi, Swetha Arumugam, Adarsh Bathula, Subhajit Dandapat, Debabrata Deb, Churchil Dwivedi, Yashwant Gupta, Shebin Jose Jacob, Fazal Kareem, K Nobleson, Pragna Mamidipaka, Avinash Kumar Paladi, Arul Pandian B, Prerna Rana, Jaikhomba Singha, Aman Srivastava, Mayuresh Surnis, Pratik Tarafdar","doi":"10.1017/pasa.2024.30","DOIUrl":"https://doi.org/10.1017/pasa.2024.30","url":null,"abstract":"High-precision pulsar timing observations are limited in their accuracy by the jitter noise that appears in the arrival time of pulses. Therefore, it is important to systematically characterise the amplitude of the jitter noise and its variation with frequency. In this paper, we provide jitter measurements from low-frequency wideband observations of PSR J0437–4715 using data obtained as part of the Indian Pulsar Timing Array experiment. We were able to detect jitter in both the 300 - 500 MHz and 1260 - 1460 MHz observations of the upgraded Giant Metrewave Radio Telescope (uGMRT). The former is the first jitter measurement for this pulsar below 700 MHz, and the latter is in good agreement with results from previous studies. In addition, at 300 - 500 MHz, we investigated the frequency dependence of the jitter by calculating the jitter for each sub-banded arrival time of pulses. We found that the jitter amplitude increases with frequency. This trend is opposite as compared to previous studies, indicating that there is a turnover at intermediate frequencies. It will be possible to investigate this in more detail with uGMRT observations at 550 - 750 MHz and future high sensitive wideband observations from next generation telescopes, such as the Square Kilometre Array. We also explored the effect of jitter on the high precision dispersion measure (DM) measurements derived from short duration observations. We find that even though the DM precision will be better at lower frequencies due to the smaller amplitude of jitter noise, it will limit the DM precision for high signal-to-noise observations, which are of short durations. This limitation can be overcome by integrating for a long enough duration optimised for a given pulsar.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"26 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140613000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present results regarding the longitudinal migrations of cool stellar spots that exhibit remarkable oscillations and explore their possible causes. We conducted analyses using high-quality data from nine target systems of various spectral types, spanning from F to M, which were observed by the Kepler Satellite. The systems in which the behaviour of the spots was examined are as follows: KIC 4357272, KIC 6025466, KIC 6058875, KIC 6962018, KIC 7798259, KIC 9210828, KIC 11706658, KIC 12599700, and KIC 8669092. Basic stellar parameters were calculated from light curve analysis using the PHOEBE V.0.32 software, and light curves were modelled to obtain sinusoidal variations occurring out-of-eclipses phases, induced by rotational modulation. Subsequently, we calculated the minimum times of the obtained sinusoidal variations using the Fourier transform. The distributions of θmin corresponding to these minimum times over time were computed using linear fits to determine the longitudinal migrations of the spotted areas. We then compared the longitudinal migration periods with the stellar parameters found in the literature. In addition, we also found a secondary variation in the spot migrations apart from the linear models. Our results revealed that the longitudinal migration periods vary in relation to the B – V colour index of the stars.
我们介绍了表现出显著振荡的冷恒星点的纵向迁移结果，并探讨了其可能的原因。我们利用开普勒卫星观测到的从F到M不同光谱型的9个目标系统的高质量数据进行了分析。研究光斑行为的系统如下：KIC 4357272、KIC 6025466、KIC 6058875、KIC 6962018、KIC 7798259、KIC 9210828、KIC 11706658、KIC 12599700 和 KIC 8669092。基本恒星参数是通过使用 PHOEBE V.0.32 软件进行光曲线分析计算得出的，光曲线的建模是为了获得由旋转调制引起的、发生在日蚀相位外的正弦变化。随后，我们利用傅立叶变换计算所获得的正弦变化的最小时间。通过线性拟合计算出这些最小时间对应的θ min 随时间的分布，从而确定斑点区域的纵向迁移。然后，我们将纵向迁移周期与文献中的恒星参数进行了比较。此外，除了线性模型之外，我们还发现了光斑迁移的二次变化。我们的结果表明，纵向迁移周期的变化与恒星的 B - V 色指数有关。
{"title":"Some Findings from the Longitudinal Migration of Starspots","authors":"N. Ö. Kaya, H. A. Dal","doi":"10.1017/pasa.2024.28","DOIUrl":"https://doi.org/10.1017/pasa.2024.28","url":null,"abstract":"We present results regarding the longitudinal migrations of cool stellar spots that exhibit remarkable oscillations and explore their possible causes. We conducted analyses using high-quality data from nine target systems of various spectral types, spanning from F to M, which were observed by the Kepler Satellite. The systems in which the behaviour of the spots was examined are as follows: KIC 4357272, KIC 6025466, KIC 6058875, KIC 6962018, KIC 7798259, KIC 9210828, KIC 11706658, KIC 12599700, and KIC 8669092. Basic stellar parameters were calculated from light curve analysis using the PHOEBE V.0.32 software, and light curves were modelled to obtain sinusoidal variations occurring out-of-eclipses phases, induced by rotational modulation. Subsequently, we calculated the minimum times of the obtained sinusoidal variations using the Fourier transform. The distributions of θ<jats:sub> <jats:italic>min</jats:italic> </jats:sub> corresponding to these minimum times over time were computed using linear fits to determine the longitudinal migrations of the spotted areas. We then compared the longitudinal migration periods with the stellar parameters found in the literature. In addition, we also found a secondary variation in the spot migrations apart from the linear models. Our results revealed that the longitudinal migration periods vary in relation to the <jats:italic>B</jats:italic> – <jats:italic>V</jats:italic> colour index of the stars.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"56 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140585258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Priyashkumar Mistry, Aniket Prasad, Mousam Maity, Kamlesh Pathak, Sarvesh Gharat, Georgios Lekkas, Surendra Bhattarai, Dhruv Kumar, Jack J. Lissauer, Joseph D. Twicken, Abderahmane Soubkiou, Francisco J. Pozuelos, Jon Jenkins, Keith Horne, Steven Giacalone, Khalid Barkaoui, Mathilde Timmermans, Cristilyn N. Watkins, Ramotholo Sefako, Karen A. Collins, David R. Ciardi, Catherine A. Clark, Boris S. Safonov, Avi Shporer, Joshua E. Schlieder, Zouhair Benkhaldoun, Chris Stockdale, Carl Ziegler, Emily A. Gilbert, Emmanuël Jehin, Felipe Murgas, Ian J. M. Crossfield, Martin Paegert, Michael B. Lund, Norio Narita, Richard P. Schwarz, Robert F. Goeke, Sergio B. Fajardo-Acosta, Steve B. Howell, Thiam-Guan Tan, Thomas Barclay, Yugo Kawai
NASA’s all-sky survey mission, the Transiting Exoplanet Survey Satellite (TESS), is specifically engineered to detect exoplanets that transit bright stars. Thus far, TESS has successfully identified approximately 400 transiting exoplanets, in addition to roughly 6000 candidate exoplanets pending confirmation. In this study, we present the results of our ongoing project, the Validation of Transiting Exoplanets using Statistical Tools (VaTEST). Our dedicated effort is focused on the confirmation and characterization of new exoplanets through the application of statistical validation tools. Through a combination of ground-based telescope data, high-resolution imaging, and the utilization of the statistical validation tool known as TRICERATOPS, we have successfully discovered eight potential super-Earths. These planets bear the designations: TOI-238b ( R⊕), TOI-771b ( R⊕), TOI-871b ( R⊕), TOI-1467b ( R⊕), TOI-1739b ( R⊕), TOI-2068b ( R⊕), TOI-4559b ( R⊕), and TOI-5799b ( R⊕). Among all these planets, six of them fall within the region known as ’keystone planets,’ which makes them particularly interesting for study. Based on the location of TOI-771b and TOI-4559b below the radius valley we characterized them as likely super-Earths, though radial velocity mass measurements for these planets will provide more details about their characterization. It is noteworthy that planets within the size range investigated herein are absent from our own solar system, making their study crucial for gaining insights into the evolutionary stages between Earth and Neptune.
{"title":"VaTEST III: Validation of 8 Potential Super-Earths from TESS Data","authors":"Priyashkumar Mistry, Aniket Prasad, Mousam Maity, Kamlesh Pathak, Sarvesh Gharat, Georgios Lekkas, Surendra Bhattarai, Dhruv Kumar, Jack J. Lissauer, Joseph D. Twicken, Abderahmane Soubkiou, Francisco J. Pozuelos, Jon Jenkins, Keith Horne, Steven Giacalone, Khalid Barkaoui, Mathilde Timmermans, Cristilyn N. Watkins, Ramotholo Sefako, Karen A. Collins, David R. Ciardi, Catherine A. Clark, Boris S. Safonov, Avi Shporer, Joshua E. Schlieder, Zouhair Benkhaldoun, Chris Stockdale, Carl Ziegler, Emily A. Gilbert, Emmanuël Jehin, Felipe Murgas, Ian J. M. Crossfield, Martin Paegert, Michael B. Lund, Norio Narita, Richard P. Schwarz, Robert F. Goeke, Sergio B. Fajardo-Acosta, Steve B. Howell, Thiam-Guan Tan, Thomas Barclay, Yugo Kawai","doi":"10.1017/pasa.2024.29","DOIUrl":"https://doi.org/10.1017/pasa.2024.29","url":null,"abstract":"NASA’s all-sky survey mission, the Transiting Exoplanet Survey Satellite (TESS), is specifically engineered to detect exoplanets that transit bright stars. Thus far, TESS has successfully identified approximately 400 transiting exoplanets, in addition to roughly 6000 candidate exoplanets pending confirmation. In this study, we present the results of our ongoing project, the Validation of Transiting Exoplanets using Statistical Tools (VaTEST). Our dedicated effort is focused on the confirmation and characterization of new exoplanets through the application of statistical validation tools. Through a combination of ground-based telescope data, high-resolution imaging, and the utilization of the statistical validation tool known as <jats:monospace>TRICERATOPS</jats:monospace>, we have successfully discovered eight potential super-Earths. These planets bear the designations: TOI-238b (<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S1323358024000298_inline1.png\" /> R<jats:sub>⊕</jats:sub>), TOI-771b (<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S1323358024000298_inline2.png\" /> R<jats:sub>⊕</jats:sub>), TOI-871b (<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S1323358024000298_inline3.png\" /> R<jats:sub>⊕</jats:sub>), TOI-1467b (<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S1323358024000298_inline4.png\" /> R<jats:sub>⊕</jats:sub>), TOI-1739b (<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S1323358024000298_inline5.png\" /> R<jats:sub>⊕</jats:sub>), TOI-2068b (<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S1323358024000298_inline6.png\" /> R<jats:sub>⊕</jats:sub>), TOI-4559b (<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S1323358024000298_inline7.png\" /> R<jats:sub>⊕</jats:sub>), and TOI-5799b (<jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S1323358024000298_inline8.png\" /> R<jats:sub>⊕</jats:sub>). Among all these planets, six of them fall within the region known as ’keystone planets,’ which makes them particularly interesting for study. Based on the location of TOI-771b and TOI-4559b below the radius valley we characterized them as likely super-Earths, though radial velocity mass measurements for these planets will provide more details about their characterization. It is noteworthy that planets within the size range investigated herein are absent from our own solar system, making their study crucial for gaining insights into the evolutionary stages between Earth and Neptune.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"94 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140585388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N.J. Pritchard, A. Wicenec, M. Bennamoun, R. Dodson
Detecting and mitigating radio frequency interference (RFI) is critical for enabling and maximising the scientific output of radio telescopes. The emergence of machine learning (ML) methods capable of handling large datasets has led to their application in radio astronomy, particularly in RFI detection. Spiking neural networks (SNNs), inspired by biological systems, are well suited for processing spatio-temporal data. This study introduces the first exploratory application of SNNs to an astronomical data processing task, specifically RFI detection. We adapt the nearest latent neighbours (NLNs) algorithm and auto-encoder architecture proposed by previous authors to SNN execution by direct ANN2SNN conversion, enabling simplified downstream RFI detection by sampling the naturally varying latent space from the internal spiking neurons. Our subsequent evaluation aims to determine whether SNNs are viable for future RFI detection schemes. We evaluate detection performance with the simulated HERA telescope and hand-labelled LOFAR observation dataset the original authors provided. We additionally evaluate detection performance with a new MeerKAT-inspired simulation dataset that provides a technical challenge for machine-learnt RFI detection methods. This dataset focuses on satellite-based RFI, an increasingly important class of RFI and is an additional contribution. Our SNN approach remains competitive with the original NLN algorithm and AOFlagger in AUROC, AUPRC, and F1-scores for the HERA dataset but exhibits difficulty in the LOFAR and Tabascal datasets. However, our method maintains this accuracy while completely removing the compute and memory-intense latent sampling step found in NLN. This work demonstrates the viability of SNNs as a promising avenue for ML-based RFI detection in radio telescopes by establishing a minimal performance baseline on traditional and nascent satellite-based RFI sources and is the first work to our knowledge to apply SNNs in astronomy.
{"title":"RFI detection with spiking neural networks","authors":"N.J. Pritchard, A. Wicenec, M. Bennamoun, R. Dodson","doi":"10.1017/pasa.2024.27","DOIUrl":"https://doi.org/10.1017/pasa.2024.27","url":null,"abstract":"<p>Detecting and mitigating radio frequency interference (RFI) is critical for enabling and maximising the scientific output of radio telescopes. The emergence of machine learning (ML) methods capable of handling large datasets has led to their application in radio astronomy, particularly in RFI detection. Spiking neural networks (SNNs), inspired by biological systems, are well suited for processing spatio-temporal data. This study introduces the first exploratory application of SNNs to an astronomical data processing task, specifically RFI detection. We adapt the nearest latent neighbours (NLNs) algorithm and auto-encoder architecture proposed by previous authors to SNN execution by direct ANN2SNN conversion, enabling simplified downstream RFI detection by sampling the naturally varying latent space from the internal spiking neurons. Our subsequent evaluation aims to determine whether SNNs are viable for future RFI detection schemes. We evaluate detection performance with the simulated HERA telescope and hand-labelled LOFAR observation dataset the original authors provided. We additionally evaluate detection performance with a new MeerKAT-inspired simulation dataset that provides a technical challenge for machine-learnt RFI detection methods. This dataset focuses on satellite-based RFI, an increasingly important class of RFI and is an additional contribution. Our SNN approach remains competitive with the original NLN algorithm and AOFlagger in AUROC, AUPRC, and F1-scores for the HERA dataset but exhibits difficulty in the LOFAR and Tabascal datasets. However, our method maintains this accuracy while completely removing the compute and memory-intense latent sampling step found in NLN. This work demonstrates the viability of SNNs as a promising avenue for ML-based RFI detection in radio telescopes by establishing a minimal performance baseline on traditional and nascent satellite-based RFI sources and is the first work to our knowledge to apply SNNs in astronomy.</p>","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"34 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140806607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nikhel Gupta, Ray P. Norris, Zeeshan Hayder, Minh Huynh, Lars Petersson, X. Rosalind Wang, Andrew M. Hopkins, Heinz Andernach, Yjan Gordon, Simone Riggi, Miranda Yew, Evan J. Crawford, Bärbel Koribalski, Miroslav D. Filipović, Anna D. Kapińska, Stanislav Shabala, Tessa Vernstrom, Joshua R. Marvil
We present source detection and catalogue construction pipelines to build the first catalogue of radio galaxies from the 270 deg2 pilot survey of the Evolutionary Map of the Universe (EMU-PS) conducted with the Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The detection pipeline uses Gal-DINO computer-vision networks (Gupta et al., 2024) to predict the categories of radio morphology and bounding boxes for radio sources, as well as their potential infrared host positions. The Gal-DINO network is trained and evaluated on approximately 5,000 visually inspected radio galaxies and their infrared hosts, encompassing both compact and extended radio morphologies.We find that the Intersection over Union (IoU) for the predicted and ground truth bounding boxes is larger than 0.5 for 99% of the radio sources, and 98% of predicted host positions are within 3″ of the ground truth infrared host in the evaluation set. The catalogue construction pipeline uses the predictions of the trained network on the radio and infrared image cutouts based on the catalogue of radio components identified using the Selavy source finder algorithm. Confidence scores of the predictions are then used to prioritize Selavy components with higher scores and incorporate them first into the catalogue. This results in identifications for a total of 211,625 radio sources, with 201,211 classified as compact and unresolved. The remaining 10,414 are categorized as extended radio morphologies, including 582 FR-I, 5,602 FR-II, 1,494 FR-x (uncertain whether FR-I or FR-II), 2,375 R (single-peak resolved) radio galaxies, and 361 with peculiar and other rare morphologies. Each source in the catalogue includes a confidence score.We cross-match the radio sources in the catalogue with the infrared and optical catalogues, finding infrared cross-matches for 73% and photometric redshifts for 36% of the radio galaxies. The EMU-PS catalogue and the detection pipelines presented here will be used towards constructing catalogues for the main EMU survey covering the full southern sky.
{"title":"RG-CAT: Detection Pipeline and Catalogue of Radio Galaxies in the EMU Pilot Survey","authors":"Nikhel Gupta, Ray P. Norris, Zeeshan Hayder, Minh Huynh, Lars Petersson, X. Rosalind Wang, Andrew M. Hopkins, Heinz Andernach, Yjan Gordon, Simone Riggi, Miranda Yew, Evan J. Crawford, Bärbel Koribalski, Miroslav D. Filipović, Anna D. Kapińska, Stanislav Shabala, Tessa Vernstrom, Joshua R. Marvil","doi":"10.1017/pasa.2024.25","DOIUrl":"https://doi.org/10.1017/pasa.2024.25","url":null,"abstract":"We present source detection and catalogue construction pipelines to build the first catalogue of radio galaxies from the 270 deg<jats:sup>2</jats:sup> pilot survey of the Evolutionary Map of the Universe (EMU-PS) conducted with the Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The detection pipeline uses Gal-DINO computer-vision networks (Gupta et al., 2024) to predict the categories of radio morphology and bounding boxes for radio sources, as well as their potential infrared host positions. The Gal-DINO network is trained and evaluated on approximately 5,000 visually inspected radio galaxies and their infrared hosts, encompassing both compact and extended radio morphologies.We find that the Intersection over Union (IoU) for the predicted and ground truth bounding boxes is larger than 0.5 for 99% of the radio sources, and 98% of predicted host positions are within 3″ of the ground truth infrared host in the evaluation set. The catalogue construction pipeline uses the predictions of the trained network on the radio and infrared image cutouts based on the catalogue of radio components identified using the <jats:italic>Selavy</jats:italic> source finder algorithm. Confidence scores of the predictions are then used to prioritize <jats:italic>Selavy</jats:italic> components with higher scores and incorporate them first into the catalogue. This results in identifications for a total of 211,625 radio sources, with 201,211 classified as compact and unresolved. The remaining 10,414 are categorized as extended radio morphologies, including 582 FR-I, 5,602 FR-II, 1,494 FR-x (uncertain whether FR-I or FR-II), 2,375 R (single-peak resolved) radio galaxies, and 361 with peculiar and other rare morphologies. Each source in the catalogue includes a confidence score.We cross-match the radio sources in the catalogue with the infrared and optical catalogues, finding infrared cross-matches for 73% and photometric redshifts for 36% of the radio galaxies. The EMU-PS catalogue and the detection pipelines presented here will be used towards constructing catalogues for the main EMU survey covering the full southern sky.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"51 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140585257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Riggi, G. Umana, C. Trigilio, C. Bordiu, F. Bufano, A. Ingallinera, F. Cavallaro, Y. Gordon, R.P. Norris, G. Gürkan, P. Leto, C. Buemi, S. Loru, A.M. Hopkins, M.D. Filipović, T. Cecconello
Generation of science-ready data from processed data products is one of the major challenges in next-generation radio continuum surveys with the Square Kilometre Array (SKA) and its precursors, due to the expected data volume and the need to achieve a high degree of automated processing. Source extraction, characterization, and classification are the major stages involved in this process. In this work we focus on the classification of compact radio sources in the Galactic plane using both radio and infrared images as inputs. To this aim, we produced a curated dataset of ∼20,000 images of compact sources of different astronomical classes, obtained from past radio and infrared surveys, and novel radio data from pilot surveys carried out with the Australian SKA Pathfinder (ASKAP). Radio spectral index information was also obtained for a subset of the data. We then trained two different classifiers on the produced dataset. The first model uses gradient-boosted decision trees and is trained on a set of pre-computed features derived from the data, which include radio-infrared colour indices and the radio spectral index. The second model is trained directly on multi-channel images, employing convolutional neural networks. Using a completely supervised procedure, we obtained a high classification accuracy (F1-score>90%) for separating Galactic objects from the extragalactic background. Individual class discrimination performances, ranging from 60% to 75%, increased by 10% when adding far-infrared and spectral index information, with extragalactic objects, PNe and HII regions identified with higher accuracies. The implemented tools and trained models were publicly released, and made available to the radioastronomical community for future application on new radio data.
从处理过的数据产品中生成可用于科学研究的数据，是利用平方千米阵列（SKA）及其前身进行下一代射电连续面测量的主要挑战之一，这是因为预期的数据量和实现高度自动化处理的需要。源提取、表征和分类是这一过程的主要阶段。在这项工作中，我们的重点是利用射电和红外图像作为输入，对银河面上的紧凑射电源进行分类。为此，我们制作了一个包含 20,000 幅不同天文类别的紧凑射电源图像的数据集，这些图像来自过去的射电和红外巡天，以及澳大利亚 SKA 探路者（ASKAP）开展的试验性巡天获得的新射电数据。我们还获得了部分数据的射电光谱指数信息。然后，我们在生成的数据集上训练了两种不同的分类器。第一个模型使用梯度提升决策树，根据数据中预先计算出的一组特征进行训练，其中包括射电-红外色彩指数和射电光谱指数。第二个模型采用卷积神经网络，直接在多通道图像上进行训练。利用完全监督程序，我们获得了很高的分类准确率（F1-score>90%），可将银河系天体与河外背景区分开来。在加入远红外和光谱指数信息后，单个类别的识别率从 60% 到 75% 不等，提高了 10%，银河系外天体、PNe 和 HII 区域的识别准确率更高。实施的工具和训练的模型已公开发布，并提供给射电天文学界，供今后应用于新的射电数据。
{"title":"Classification of compact radio sources in the Galactic plane with supervised machine learning","authors":"S. Riggi, G. Umana, C. Trigilio, C. Bordiu, F. Bufano, A. Ingallinera, F. Cavallaro, Y. Gordon, R.P. Norris, G. Gürkan, P. Leto, C. Buemi, S. Loru, A.M. Hopkins, M.D. Filipović, T. Cecconello","doi":"10.1017/pasa.2024.26","DOIUrl":"https://doi.org/10.1017/pasa.2024.26","url":null,"abstract":"Generation of science-ready data from processed data products is one of the major challenges in next-generation radio continuum surveys with the Square Kilometre Array (SKA) and its precursors, due to the expected data volume and the need to achieve a high degree of automated processing. Source extraction, characterization, and classification are the major stages involved in this process. In this work we focus on the classification of compact radio sources in the Galactic plane using both radio and infrared images as inputs. To this aim, we produced a curated dataset of ∼20,000 images of compact sources of different astronomical classes, obtained from past radio and infrared surveys, and novel radio data from pilot surveys carried out with the Australian SKA Pathfinder (ASKAP). Radio spectral index information was also obtained for a subset of the data. We then trained two different classifiers on the produced dataset. The first model uses gradient-boosted decision trees and is trained on a set of pre-computed features derived from the data, which include radio-infrared colour indices and the radio spectral index. The second model is trained directly on multi-channel images, employing convolutional neural networks. Using a completely supervised procedure, we obtained a high classification accuracy (F1-score>90%) for separating Galactic objects from the extragalactic background. Individual class discrimination performances, ranging from 60% to 75%, increased by 10% when adding far-infrared and spectral index information, with extragalactic objects, PNe and HII regions identified with higher accuracies. The implemented tools and trained models were publicly released, and made available to the radioastronomical community for future application on new radio data.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"100 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140585410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. W. Duchesne, A. Botteon, B. S. Koribalski, F. Loi, K. Rajpurohit, C. J. Riseley, L. Rudnick, T. Vernstrom, H. Andernach, A. M. Hopkins, A. D. Kapinska, R. P. Norris, T. Zafar
Clusters of galaxies have been found to host Mpc-scale diffuse, non-thermal radio emission in the form of central radio halos and peripheral relics. Turbulence and shock-related processes in the intra-cluster medium are generally considered responsible for the emission, though details of these processes are still not clear. The low surface brightness makes detection of the emission a challenge, but with recent surveys with high-sensitivity radio telescopes we are beginning to build large samples of these sources. The Evolutionary Map of the Universe (EMU) is a Southern Sky survey being performed by the Australian SKA Pathfinder (ASKAP) over the next few years and is well-suited to detect and characterise such emission. To assess prospects of the full survey, we have performed a pilot search of diffuse sources in 71 clusters from the Planck Sunyaev–Zeldovich (SZ) cluster catalogue (PSZ2) found in archival ASKAP observations. After re-imaging the archival data and performing both (u, v)-plane and image-plane angular scale filtering, we detect 21 radio halos (12 for the first time, excluding an additional six candidates), 11 relics (in seven clusters, and six for the first time, excluding a further five candidate relics), along with 12 other, unclassified diffuse radio sources. From these detections, we predict the full EMU survey will uncover up to ≈ 254 radio halos and ≈ 85 radio relics in the 858 PSZ2 clusters that will be covered by EMU. The percentage of clusters found to host diffuse emission in this work is similar to the number reported in recent cluster surveys with the LOw Frequency ARray (LOFAR) Two-metre Sky Survey (Botteon, et al. 2022a, A&A, 660, A78), suggesting EMU will complement similar searches being performed in the Northern Sky and provide us with statistically significant samples of halos and relics at the completion of the full survey. This work presents the first step towards large samples of the diffuse radio sources in Southern Sky clusters with ASKAP and eventually the SKA.
{"title":"Evolutionary Map of the Universe (EMU): a pilot search for diffuse, non-thermal radio emission in galaxy clusters with the Australian SKA Pathfinder","authors":"S. W. Duchesne, A. Botteon, B. S. Koribalski, F. Loi, K. Rajpurohit, C. J. Riseley, L. Rudnick, T. Vernstrom, H. Andernach, A. M. Hopkins, A. D. Kapinska, R. P. Norris, T. Zafar","doi":"10.1017/pasa.2024.10","DOIUrl":"https://doi.org/10.1017/pasa.2024.10","url":null,"abstract":"Clusters of galaxies have been found to host Mpc-scale diffuse, non-thermal radio emission in the form of central radio halos and peripheral relics. Turbulence and shock-related processes in the intra-cluster medium are generally considered responsible for the emission, though details of these processes are still not clear. The low surface brightness makes detection of the emission a challenge, but with recent surveys with high-sensitivity radio telescopes we are beginning to build large samples of these sources. The Evolutionary Map of the Universe (EMU) is a Southern Sky survey being performed by the Australian SKA Pathfinder (ASKAP) over the next few years and is well-suited to detect and characterise such emission. To assess prospects of the full survey, we have performed a pilot search of diffuse sources in 71 clusters from the <jats:italic>Planck</jats:italic> Sunyaev–Zeldovich (SZ) cluster catalogue (PSZ2) found in archival ASKAP observations. After re-imaging the archival data and performing both (<jats:italic>u</jats:italic>, <jats:italic>v</jats:italic>)-plane and image-plane angular scale filtering, we detect 21 radio halos (12 for the first time, excluding an additional six candidates), 11 relics (in seven clusters, and six for the first time, excluding a further five candidate relics), along with 12 other, unclassified diffuse radio sources. From these detections, we predict the full EMU survey will uncover up to ≈ 254 radio halos and ≈ 85 radio relics in the 858 PSZ2 clusters that will be covered by EMU. The percentage of clusters found to host diffuse emission in this work is similar to the number reported in recent cluster surveys with the LOw Frequency ARray (LOFAR) Two-metre Sky Survey (Botteon, et al. 2022a, A&A, 660, A78), suggesting EMU will complement similar searches being performed in the Northern Sky and provide us with statistically significant samples of halos and relics at the completion of the full survey. This work presents the first step towards large samples of the diffuse radio sources in Southern Sky clusters with ASKAP and eventually the SKA.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"94 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140585390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：