Pub Date : 2024-09-19DOI: 10.1051/0004-6361/202449609
B. Aussel, S. Kruk, M. Walmsley, M. Huertas-Company, M. Castellano, C. J. Conselice, M. Delli Veneri, H. Domínguez Sánchez, P.-A. Duc, J. H. Knapen, U. Kuchner, A. La Marca, B. Margalef-Bentabol, F. R. Marleau, G. Stevens, Y. Toba, C. Tortora, L. Wang, N. Aghanim, B. Altieri, A. Amara, S. Andreon, N. Auricchio, M. Baldi, S. Bardelli, R. Bender, C. Bodendorf, D. Bonino, E. Branchini, M. Brescia, J. Brinchmann, S. Camera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, S. Cavuoti, A. Cimatti, G. Congedo, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, A. M. Di Giorgio, J. Dinis, F. Dubath, X. Dupac, S. Dusini, M. Farina, S. Farrens, S. Ferriol, S. Fotopoulou, M. Frailis, E. Franceschi, P. Franzetti, M. Fumana, S. Galeotta, B. Garilli, B. Gillis, C. Giocoli, A. Grazian, F. Grupp, S. V. H. Haugan, W. Holmes, I. Hook, F. Hormuth, A. Hornstrup, P. Hudelot, K. Jahnke, E. Keihänen, S. Kermiche, A. Kiessling, M. Kilbinger, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, R. Laureijs, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, E. Maiorano, O. Mansutti, O. Marggraf, K. Markovic, N. Martinet, F. Marulli, R. Massey, S. Maurogordato, E. Medinaceli, S. Mei, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, M. Moresco, L. Moscardini, E. Munari, S.-M. Niemi, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, E. Rossetti, R. Saglia, D. Sapone, B. Sartoris, M. Schirmer, P. Schneider, A. Secroun, G. Seidel, S. Serrano, C. Sirignano, G. Sirri, L. Stanco, J.-L. Starck, P. Tallada-Crespí, A. N. Taylor, H. I. Teplitz, I. Tereno, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, E. A. Valentijn, L. Valenziano, T. Vassallo, A. Veropalumbo, Y. Wang, J. Weller, A. Zacchei, G. Zamorani, J. Zoubian, E. Zucca, A. Biviano, M. Bolzonella, A. Boucaud, E. Bozzo, C. Burigana, C. Colodro-Conde, D. Di Ferdinando, R. Farinelli, J. Graciá-Carpio, G. Mainetti, S. Marcin, N. Mauri, C. Neissner, A. A. Nucita, Z. Sakr, V. Scottez, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, V. Allevato, S. Anselmi, C. Baccigalupi, M. Ballardini, S. Borgani, A. S. Borlaff, H. Bretonnière, S. Bruton, R. Cabanac, A. Calabro, A. Cappi, C. S. Carvalho, G. Castignani, T. Castro, G. Cañas-Herrera, K. C. Chambers, J. Coupon, O. Cucciati, S. Davini, G. De Lucia, G. Desprez, S. Di Domizio, H. Dole, A. Díaz-Sánchez, J. A. Escartin Vigo, S. Escoffier, I. Ferrero, F. Finelli, L. Gabarra, K. Ganga, J. García-Bellido, E. Gaztanaga, K. George, F. Giacomini, G. Gozaliasl, A. Gregorio, D. Guinet, A. Hall, H. Hildebrandt, A. Jimenez Muñoz, J. J. E. Kajava, V. Kansal, D. Karagiannis, C. C. Kirkpatrick, L. Legrand, A. Loureiro, J. Macias-Perez, M. Magliocchetti, R. Maoli, M. Martinelli, C. J. A. P. Martins, S. Matthew, M. Maturi, L. Maurin, R. B. Metcalf, M. Migliaccio, P. Monaco, G. Morgante, S. Nadathur, Nicholas A. Walton, A. Peel, A. Pezzotta, V. Popa, C. Porciani, D. Potter, M. Pöntinen, P. Reimberg, P.-F. Rocci, A. G. Sánchez, A. Schneider, E. Sefusatti, M. Sereno, P. Simon, A. Spurio Mancini, S. A. Stanford, J. Steinwagner, G. Testera, M. Tewes, R. Teyssier, S. Toft, S. Tosi, A. Troja, M. Tucci, C. Valieri, J. Valiviita, D. Vergani, I. A. Zinchenko
The Euclid mission is expected to image millions of galaxies at high resolution, providing an extensive dataset with which to study galaxy evolution. Because galaxy morphology is both a fundamental parameter and one that is hard to determine for large samples, we investigate the application of deep learning in predicting the detailed morphologies of galaxies in Euclid using Zoobot, a convolutional neural network pretrained with 450 000 galaxies from the Galaxy Zoo project. We adapted Zoobot for use with emulated Euclid images generated based on Hubble Space Telescope COSMOS images and with labels provided by volunteers in the Galaxy Zoo: Hubble project. We experimented with different numbers of galaxies and various magnitude cuts during the training process. We demonstrate that the trained Zoobot model successfully measures detailed galaxy morphology in emulated Euclid images. It effectively predicts whether a galaxy has features and identifies and characterises various features, such as spiral arms, clumps, bars, discs, and central bulges. When compared to volunteer classifications, Zoobot achieves mean vote fraction deviations of less than 12% and an accuracy of above 91% for the confident volunteer classifications across most morphology types. However, the performance varies depending on the specific morphological class. For the global classes, such as disc or smooth galaxies, the mean deviations are less than 10%, with only 1000 training galaxies necessary to reach this performance. On the other hand, for more detailed structures and complex tasks, such as detecting and counting spiral arms or clumps, the deviations are slightly higher, of namely around 12% with 60 000 galaxies used for training. In order to enhance the performance on complex morphologies, we anticipate that a larger pool of labelled galaxies is needed, which could be obtained using crowd sourcing. We estimate that, with our model, the detailed morphology of approximately 800 million galaxies of the Euclid Wide Survey could be reliably measured and that approximately 230 million of these galaxies would display features. Finally, our findings imply that the model can be effectively adapted to new morphological labels. We demonstrate this adaptability by applying Zoobot to peculiar galaxies. In summary, our trained Zoobot CNN can readily predict morphological catalogues for Euclid images.
{"title":"Euclid preparation","authors":"B. Aussel, S. Kruk, M. Walmsley, M. Huertas-Company, M. Castellano, C. J. Conselice, M. Delli Veneri, H. Domínguez Sánchez, P.-A. Duc, J. H. Knapen, U. Kuchner, A. La Marca, B. Margalef-Bentabol, F. R. Marleau, G. Stevens, Y. Toba, C. Tortora, L. Wang, N. Aghanim, B. Altieri, A. Amara, S. Andreon, N. Auricchio, M. Baldi, S. Bardelli, R. Bender, C. Bodendorf, D. Bonino, E. Branchini, M. Brescia, J. Brinchmann, S. Camera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, S. Cavuoti, A. Cimatti, G. Congedo, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, A. M. Di Giorgio, J. Dinis, F. Dubath, X. Dupac, S. Dusini, M. Farina, S. Farrens, S. Ferriol, S. Fotopoulou, M. Frailis, E. Franceschi, P. Franzetti, M. Fumana, S. Galeotta, B. Garilli, B. Gillis, C. Giocoli, A. Grazian, F. Grupp, S. V. H. Haugan, W. Holmes, I. Hook, F. Hormuth, A. Hornstrup, P. Hudelot, K. Jahnke, E. Keihänen, S. Kermiche, A. Kiessling, M. Kilbinger, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, R. Laureijs, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, E. Maiorano, O. Mansutti, O. Marggraf, K. Markovic, N. Martinet, F. Marulli, R. Massey, S. Maurogordato, E. Medinaceli, S. Mei, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, M. Moresco, L. Moscardini, E. Munari, S.-M. Niemi, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, E. Rossetti, R. Saglia, D. Sapone, B. Sartoris, M. Schirmer, P. Schneider, A. Secroun, G. Seidel, S. Serrano, C. Sirignano, G. Sirri, L. Stanco, J.-L. Starck, P. Tallada-Crespí, A. N. Taylor, H. I. Teplitz, I. Tereno, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, E. A. Valentijn, L. Valenziano, T. Vassallo, A. Veropalumbo, Y. Wang, J. Weller, A. Zacchei, G. Zamorani, J. Zoubian, E. Zucca, A. Biviano, M. Bolzonella, A. Boucaud, E. Bozzo, C. Burigana, C. Colodro-Conde, D. Di Ferdinando, R. Farinelli, J. Graciá-Carpio, G. Mainetti, S. Marcin, N. Mauri, C. Neissner, A. A. Nucita, Z. Sakr, V. Scottez, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, V. Allevato, S. Anselmi, C. Baccigalupi, M. Ballardini, S. Borgani, A. S. Borlaff, H. Bretonnière, S. Bruton, R. Cabanac, A. Calabro, A. Cappi, C. S. Carvalho, G. Castignani, T. Castro, G. Cañas-Herrera, K. C. Chambers, J. Coupon, O. Cucciati, S. Davini, G. De Lucia, G. Desprez, S. Di Domizio, H. Dole, A. Díaz-Sánchez, J. A. Escartin Vigo, S. Escoffier, I. Ferrero, F. Finelli, L. Gabarra, K. Ganga, J. García-Bellido, E. Gaztanaga, K. George, F. Giacomini, G. Gozaliasl, A. Gregorio, D. Guinet, A. Hall, H. Hildebrandt, A. Jimenez Muñoz, J. J. E. Kajava, V. Kansal, D. Karagiannis, C. C. Kirkpatrick, L. Legrand, A. Loureiro, J. Macias-Perez, M. Magliocchetti, R. Maoli, M. Martinelli, C. J. A. P. Martins, S. Matthew, M. Maturi, L. Maurin, R. B. Metcalf, M. Migliaccio, P. Monaco, G. Morgante, S. Nadathur, Nicholas A. Walton, A. Peel, A. Pezzotta, V. Popa, C. Porciani, D. Potter, M. Pöntinen, P. Reimberg, P.-F. Rocci, A. G. Sánchez, A. Schneider, E. Sefusatti, M. Sereno, P. Simon, A. Spurio Mancini, S. A. Stanford, J. Steinwagner, G. Testera, M. Tewes, R. Teyssier, S. Toft, S. Tosi, A. Troja, M. Tucci, C. Valieri, J. Valiviita, D. Vergani, I. A. Zinchenko","doi":"10.1051/0004-6361/202449609","DOIUrl":"https://doi.org/10.1051/0004-6361/202449609","url":null,"abstract":"The <i>Euclid<i/> mission is expected to image millions of galaxies at high resolution, providing an extensive dataset with which to study galaxy evolution. Because galaxy morphology is both a fundamental parameter and one that is hard to determine for large samples, we investigate the application of deep learning in predicting the detailed morphologies of galaxies in <i>Euclid<i/> using Zoobot, a convolutional neural network pretrained with 450 000 galaxies from the Galaxy Zoo project. We adapted Zoobot for use with emulated <i>Euclid<i/> images generated based on <i>Hubble<i/> Space Telescope COSMOS images and with labels provided by volunteers in the Galaxy Zoo: Hubble project. We experimented with different numbers of galaxies and various magnitude cuts during the training process. We demonstrate that the trained Zoobot model successfully measures detailed galaxy morphology in emulated <i>Euclid<i/> images. It effectively predicts whether a galaxy has features and identifies and characterises various features, such as spiral arms, clumps, bars, discs, and central bulges. When compared to volunteer classifications, Zoobot achieves mean vote fraction deviations of less than 12% and an accuracy of above 91% for the confident volunteer classifications across most morphology types. However, the performance varies depending on the specific morphological class. For the global classes, such as disc or smooth galaxies, the mean deviations are less than 10%, with only 1000 training galaxies necessary to reach this performance. On the other hand, for more detailed structures and complex tasks, such as detecting and counting spiral arms or clumps, the deviations are slightly higher, of namely around 12% with 60 000 galaxies used for training. In order to enhance the performance on complex morphologies, we anticipate that a larger pool of labelled galaxies is needed, which could be obtained using crowd sourcing. We estimate that, with our model, the detailed morphology of approximately 800 million galaxies of the Euclid Wide Survey could be reliably measured and that approximately 230 million of these galaxies would display features. Finally, our findings imply that the model can be effectively adapted to new morphological labels. We demonstrate this adaptability by applying Zoobot to peculiar galaxies. In summary, our trained Zoobot CNN can readily predict morphological catalogues for <i>Euclid<i/> images.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142276007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1051/0004-6361/202451441
A. Nindos, S. Patsourakos, K. Moraitis, V. Archontis, E. Liokati, M. K. Georgoulis, A. A. Norton
Using photospheric vector magnetograms obtained by the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory and a magnetic connectivity-based method, we computed the magnetic helicity and free magnetic energy budgets of a simple bipolar solar active region (AR) during its magnetic flux-emergence phase, which lasted ∼47 h. The AR did not produce any coronal mass ejections (CMEs) or flares with an X-ray class above C1.0, but it was the site of 60 jet events during its flux-emergence phase. The helicity and free energy budgets of the AR were below established eruption-related thresholds throughout the interval we studied. However, in addition to their slowly varying evolution, each of the time profiles of the helicity and free energy budgets showed discrete localized peaks, with eight pairs of them occurring at times of jets emanating from the AR. These jets featured larger base areas and longer durations than the other jets of the AR. We estimated, for the first time, the helicity and free magnetic energy changes associated with these eight jets, which were in the ranges of 0.5 − 7.1 × 1040 Mx2 and 1.1 − 6.9 × 1029 erg, respectively. Although these values are one to two orders of magnitude smaller than those usually associated with CMEs, the relevant percentage changes were significant and ranged from 13% to 76% for the normalized helicity and from 9% to 57% for the normalized free magnetic energy. Our study indicates that jets may occasionally have a significant imprint in the evolution of helicity and free magnetic energy budgets of emerging ARs.
{"title":"Magnetic helicity and energy budgets of jet events from an emerging solar active region","authors":"A. Nindos, S. Patsourakos, K. Moraitis, V. Archontis, E. Liokati, M. K. Georgoulis, A. A. Norton","doi":"10.1051/0004-6361/202451441","DOIUrl":"https://doi.org/10.1051/0004-6361/202451441","url":null,"abstract":"Using photospheric vector magnetograms obtained by the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory and a magnetic connectivity-based method, we computed the magnetic helicity and free magnetic energy budgets of a simple bipolar solar active region (AR) during its magnetic flux-emergence phase, which lasted ∼47 h. The AR did not produce any coronal mass ejections (CMEs) or flares with an X-ray class above C1.0, but it was the site of 60 jet events during its flux-emergence phase. The helicity and free energy budgets of the AR were below established eruption-related thresholds throughout the interval we studied. However, in addition to their slowly varying evolution, each of the time profiles of the helicity and free energy budgets showed discrete localized peaks, with eight pairs of them occurring at times of jets emanating from the AR. These jets featured larger base areas and longer durations than the other jets of the AR. We estimated, for the first time, the helicity and free magnetic energy changes associated with these eight jets, which were in the ranges of 0.5 − 7.1 × 10<sup>40<sup/> Mx<sup>2<sup/> and 1.1 − 6.9 × 10<sup>29<sup/> erg, respectively. Although these values are one to two orders of magnitude smaller than those usually associated with CMEs, the relevant percentage changes were significant and ranged from 13% to 76% for the normalized helicity and from 9% to 57% for the normalized free magnetic energy. Our study indicates that jets may occasionally have a significant imprint in the evolution of helicity and free magnetic energy budgets of emerging ARs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142245621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1051/0004-6361/202449837
S. Celli, G. Peron
Context. The recent discovery of several ultra high-energy gamma-ray emitters in our Galaxy represents a significant advancement towards the characterisation of its most powerful accelerators. Nonetheless, in order to unambiguously locate the regions where the highest energy particles are produced and understand the responsible physical mechanisms, detailed spectral and morphological studies are required, especially given that most of the observed sources were found to be significantly extended.Aims. In these regards, pointing observations with the next-generation Imaging Atmospheric Cherenkov Telescopes, such as the Cherenkov Telescope Array (CTA) Observatory and the ASTRI Mini-Array (ASTRI), are expected to provide significant improvements. Here we aim to identify the most promising sources to target in future observations.Methods. For this purpose, we performed a comparative analysis of the expected performance of ASTRI and CTA, computing their differential sensitivities towards extended sources, and further explored their capabilities with respect to specific case studies, including follow-ups of existing gamma-ray source catalogues.Results. We find that almost all of the sources thus far detected by LHAASO-WCDA and in the H.E.S.S. Galactic Plane Survey will be in the reach of ASTRI and CTA with about 300 and 50 hours of exposure, respectively. For the highest energy emitters detected by LHAASO-KM2A, in turn, we provide a list of the most promising objects that would require further investigation. We additionally examined specific classes of sources in order to identify potentially detectable gamma-ray emitters, such as passive molecular clouds (i.e. illuminated by the cosmic-ray sea) and pulsars surrounded by a halo of runaway particles.
{"title":"Detection prospects of very and ultra high-energy gamma rays from extended sources with ASTRI, CTA, and LHAASO","authors":"S. Celli, G. Peron","doi":"10.1051/0004-6361/202449837","DOIUrl":"https://doi.org/10.1051/0004-6361/202449837","url":null,"abstract":"<i>Context<i/>. The recent discovery of several ultra high-energy gamma-ray emitters in our Galaxy represents a significant advancement towards the characterisation of its most powerful accelerators. Nonetheless, in order to unambiguously locate the regions where the highest energy particles are produced and understand the responsible physical mechanisms, detailed spectral and morphological studies are required, especially given that most of the observed sources were found to be significantly extended.<i>Aims<i/>. In these regards, pointing observations with the next-generation Imaging Atmospheric Cherenkov Telescopes, such as the Cherenkov Telescope Array (CTA) Observatory and the ASTRI Mini-Array (ASTRI), are expected to provide significant improvements. Here we aim to identify the most promising sources to target in future observations.<i>Methods<i/>. For this purpose, we performed a comparative analysis of the expected performance of ASTRI and CTA, computing their differential sensitivities towards extended sources, and further explored their capabilities with respect to specific case studies, including follow-ups of existing gamma-ray source catalogues.<i>Results<i/>. We find that almost all of the sources thus far detected by LHAASO-WCDA and in the H.E.S.S. Galactic Plane Survey will be in the reach of ASTRI and CTA with about 300 and 50 hours of exposure, respectively. For the highest energy emitters detected by LHAASO-KM2A, in turn, we provide a list of the most promising objects that would require further investigation. We additionally examined specific classes of sources in order to identify potentially detectable gamma-ray emitters, such as passive molecular clouds (i.e. illuminated by the cosmic-ray sea) and pulsars surrounded by a halo of runaway particles.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142245620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1051/0004-6361/202451856
C. G. Bassa, F. Di Vruno, B. Winkel, G. I. G. Józsa, M. A. Brentjens, X. Zhang
We report on the detection of unintended electromagnetic radiation (UEMR) from the second-generation of Starlink satellites. Observations with the LOFAR radio telescope between 10 to 88 MHz and 110 to 188 MHz show broadband emission covering the frequency ranges from 40 to 70 MHz and 110 to 188 MHz from the v2-Mini and v2-Mini Direct-to-Cell Starlink satellites. The spectral power flux density of this broadband UEMR varies from satellite to satellite, with values ranging from 15 to 1300 Jy, between 56 and 66 MHz, and from 2 to 100 Jy over two distinct 8 MHz frequency ranges centered at 120 and 161 MHz. We compared the detected power flux densities of this UEMR to that emitted by the first generation v1.0 and v1.5 Starlink satellites. When correcting for the observed satellite distances, we find that the second-generation satellites emit UEMR that is up to a factor of 32 stronger compared to the first generation. The calculated electric field strengths of the detected UEMR exceed typical electromagnetic compatibility standards used for commercial electronic devices as well as recommended emission thresholds from the Radiocommunication Sector of the International Telecommunications Union (ITU-R) aimed at protecting the 150.05–153 MHz frequency range allocated to radio astronomy. We characterize the properties of the detected UEMR with the aim of assisting the satellite operator with the identification of the cause of the UEMR.
{"title":"Bright unintended electromagnetic radiation from second-generation Starlink satellites","authors":"C. G. Bassa, F. Di Vruno, B. Winkel, G. I. G. Józsa, M. A. Brentjens, X. Zhang","doi":"10.1051/0004-6361/202451856","DOIUrl":"https://doi.org/10.1051/0004-6361/202451856","url":null,"abstract":"We report on the detection of unintended electromagnetic radiation (UEMR) from the second-generation of Starlink satellites. Observations with the LOFAR radio telescope between 10 to 88 MHz and 110 to 188 MHz show broadband emission covering the frequency ranges from 40 to 70 MHz and 110 to 188 MHz from the v2-Mini and v2-Mini Direct-to-Cell Starlink satellites. The spectral power flux density of this broadband UEMR varies from satellite to satellite, with values ranging from 15 to 1300 Jy, between 56 and 66 MHz, and from 2 to 100 Jy over two distinct 8 MHz frequency ranges centered at 120 and 161 MHz. We compared the detected power flux densities of this UEMR to that emitted by the first generation v1.0 and v1.5 Starlink satellites. When correcting for the observed satellite distances, we find that the second-generation satellites emit UEMR that is up to a factor of 32 stronger compared to the first generation. The calculated electric field strengths of the detected UEMR exceed typical electromagnetic compatibility standards used for commercial electronic devices as well as recommended emission thresholds from the Radiocommunication Sector of the International Telecommunications Union (ITU-R) aimed at protecting the 150.05–153 MHz frequency range allocated to radio astronomy. We characterize the properties of the detected UEMR with the aim of assisting the satellite operator with the identification of the cause of the UEMR.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142245619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1051/0004-6361/202449610
Benoît Commerçon, Francesco Lovascio, Elliot Lynch, Enrico Ragusa
Context. Recent observations have begun probing the early phases of disc formation, but little data yet exists on disc structure and morphology of Class 0 objects. Using simulations, we are able to lay out predictions of disc morphologies expected in future surveys of young discs. Based on detailed simulations of ab initio star formation by core collapse, we predict that early discs must be eccentric.Aims. In this Letter, we study the morphology and, in particular, the eccentricity of discs formed in non-ideal magnetohydrodynamic (MHD) collapse simulations. We attempt to show that discs formed by cloud collapse are likely to be eccentric.Methods. We ran non-ideal MHD collapse simulations in the adaptive mesh refinement code RAMSES with radiative transfer. We used state-of-the-art analysis methods to measure the disc eccentricity.Results. We find that despite no asymmetry in the initial conditions, the discs formed are eccentric, with eccentricities on the order of 0.1.Conclusions. These results may have important implications for protoplanetary disc dynamics and planet formation. The presence of eccentricity in young discs that is not seen at later stages of disc evolution is in tension with current viscous eccentricity damping models. This implies that there may be an as-yet undiscovered circularisation mechanism in circumstellar discs.
背景最近的观测已经开始探测圆盘形成的早期阶段，但关于0级天体的圆盘结构和形态的数据还很少。通过模拟，我们能够对未来年轻圆盘巡天观测中的圆盘形态做出预测。在这封信中，我们研究了在非理想磁流体力学（MHD）坍缩模拟中形成的星盘的形态，特别是其偏心率。我们试图证明云坍缩形成的圆盘很可能是偏心的。我们在带有辐射传递的自适应网格细化代码 RAMSES 中运行了非理想 MHD 塌陷模拟。我们使用了最先进的分析方法来测量圆盘偏心率。我们发现，尽管初始条件不对称，但形成的圆盘是偏心的，偏心率约为 0.1。这些结果可能会对原行星盘动力学和行星形成产生重要影响。年轻圆盘中存在的偏心现象在圆盘演化的后期阶段是看不到的，这与目前的粘性偏心阻尼模型相矛盾。这意味着环星盘中可能存在一种尚未发现的圆化机制。
{"title":"Discs are born eccentric","authors":"Benoît Commerçon, Francesco Lovascio, Elliot Lynch, Enrico Ragusa","doi":"10.1051/0004-6361/202449610","DOIUrl":"https://doi.org/10.1051/0004-6361/202449610","url":null,"abstract":"<i>Context.<i/> Recent observations have begun probing the early phases of disc formation, but little data yet exists on disc structure and morphology of Class 0 objects. Using simulations, we are able to lay out predictions of disc morphologies expected in future surveys of young discs. Based on detailed simulations of ab initio star formation by core collapse, we predict that early discs must be eccentric.<i>Aims.<i/> In this Letter, we study the morphology and, in particular, the eccentricity of discs formed in non-ideal magnetohydrodynamic (MHD) collapse simulations. We attempt to show that discs formed by cloud collapse are likely to be eccentric.<i>Methods.<i/> We ran non-ideal MHD collapse simulations in the adaptive mesh refinement code RAMSES with radiative transfer. We used state-of-the-art analysis methods to measure the disc eccentricity.<i>Results.<i/> We find that despite no asymmetry in the initial conditions, the discs formed are eccentric, with eccentricities on the order of 0.1.<i>Conclusions.<i/> These results may have important implications for protoplanetary disc dynamics and planet formation. The presence of eccentricity in young discs that is not seen at later stages of disc evolution is in tension with current viscous eccentricity damping models. This implies that there may be an as-yet undiscovered circularisation mechanism in circumstellar discs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142236167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1051/0004-6361/202450043
Jyotirmoy Dey, Jagadheep D. Pandian, Dharam V. Lal, Michael R. Rugel, Andreas Brunthaler, Karl M. Menten, Friedrich Wyrowski, Nirupam Roy, Sergio A. Dzib, Sac-Nicté X. Medina, Sarwar Khan, Rohit Dokara
Context. H II regions are the signposts of massive (M ≥ 8 M⊙) star-forming sites in our Galaxy. It has been observed that the ionizing photon rate inferred from the radio continuum emission of H II regions is significantly lower (~90%) than that inferred from far-infrared fluxes measured by the Infrared Astronomical Satellite.Aims. This discrepancy in the ionizing photon rates may arise due to there being significant amounts of dust within the H II regions or the presence of extended emission that is undetected by high-resolution radio interferometric observations. Here, we study a sample of eight compact and ultracompact H II regions with extended emission to explore its role in resolving the discrepancy.Methods. We have used observations at the upgraded Giant Metrewave Radio Telescope (1.25–1.45 GHz) and data from the GLOSTAR survey (4–8 GHz) to estimate the ionizing photon rate from the radio continuum emission. We have also estimated the ionizing photon rate from the infrared luminosity by fitting a spectral energy distribution function to the infrared data from the Spitzer-GLIMPSE, MIPSGAL, and Hi-GAL surveys. The excellent sensitivity of the radio observations to extended emission allows us to investigate the actual fraction of ionizing photons that are absorbed by dust in compact and ultracompact H II regions.Results. Barring one source, we find a direct association between the radio continuum emission from the compact and diffuse components of the H II region. Our study shows that the ionizing photon rates estimated using the radio and infrared data are within reasonable agreement (5–28%) if we include the extended emission. We also find multiple candidate ionizing stars in all our sources, and the ionizing photon rates from the radio observations and candidate stars are in reasonable agreement.
背景H II 区域是银河系中大质量（M ≥ 8 M⊙）恒星形成地点的标志。据观测，从 H II 区域的射电连续波发射推断出的电离光子率（约 90%）明显低于从红外天文卫星测量的远红外通量推断出的电离光子率。电离光子率的这种差异可能是由于 H II 区域内存在大量尘埃，或者存在高分辨率射电干涉测量观测未能探测到的扩展发射。在这里，我们研究了八个具有延伸发射的紧凑和超紧凑 H II 区域样本，以探索其在解决差异中的作用。我们利用升级后的巨型移波射电望远镜（1.25-1.45 GHz）的观测数据和 GLOSTAR 勘测（4-8 GHz）的数据，从射电连续发射中估算电离光子率。我们还通过对来自 Spitzer-GLIMPSE、MIPSGAL 和 Hi-GAL 勘测的红外数据进行光谱能量分布函数拟合，估算出了来自红外发光度的电离光子率。射电观测对扩展辐射的灵敏度极高，使我们能够研究紧凑和超紧凑 H II 区域中被尘埃吸收的电离光子的实际比例。除了一个源之外，我们发现来自 H II 区域紧凑部分和弥漫部分的射电连续发射之间存在直接联系。我们的研究表明，如果将扩展辐射包括在内，利用射电和红外数据估算出的电离光子率是合理一致的（5-28%）。我们还在所有星源中发现了多颗候选电离星，而且无线电观测数据和候选星的电离光子率也基本吻合。
{"title":"A multi-wavelength study of Galactic H II regions with extended emission","authors":"Jyotirmoy Dey, Jagadheep D. Pandian, Dharam V. Lal, Michael R. Rugel, Andreas Brunthaler, Karl M. Menten, Friedrich Wyrowski, Nirupam Roy, Sergio A. Dzib, Sac-Nicté X. Medina, Sarwar Khan, Rohit Dokara","doi":"10.1051/0004-6361/202450043","DOIUrl":"https://doi.org/10.1051/0004-6361/202450043","url":null,"abstract":"<i>Context<i/>. H II regions are the signposts of massive (<i>M<i/> ≥ 8 <i>M<i/><sub>⊙<sub/>) star-forming sites in our Galaxy. It has been observed that the ionizing photon rate inferred from the radio continuum emission of H II regions is significantly lower (~90%) than that inferred from far-infrared fluxes measured by the Infrared Astronomical Satellite.<i>Aims<i/>. This discrepancy in the ionizing photon rates may arise due to there being significant amounts of dust within the H II regions or the presence of extended emission that is undetected by high-resolution radio interferometric observations. Here, we study a sample of eight compact and ultracompact H II regions with extended emission to explore its role in resolving the discrepancy.<i>Methods<i/>. We have used observations at the upgraded Giant Metrewave Radio Telescope (1.25–1.45 GHz) and data from the GLOSTAR survey (4–8 GHz) to estimate the ionizing photon rate from the radio continuum emission. We have also estimated the ionizing photon rate from the infrared luminosity by fitting a spectral energy distribution function to the infrared data from the <i>Spitzer-<i/>GLIMPSE, MIPSGAL, and Hi-GAL surveys. The excellent sensitivity of the radio observations to extended emission allows us to investigate the actual fraction of ionizing photons that are absorbed by dust in compact and ultracompact H II regions.<i>Results<i/>. Barring one source, we find a direct association between the radio continuum emission from the compact and diffuse components of the H II region. Our study shows that the ionizing photon rates estimated using the radio and infrared data are within reasonable agreement (5–28%) if we include the extended emission. We also find multiple candidate ionizing stars in all our sources, and the ionizing photon rates from the radio observations and candidate stars are in reasonable agreement.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142236163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1051/0004-6361/202450957
A. Castro-González, V. Bourrier, J. Lillo-Box, J.-B. Delisle, D. J. Armstrong, D. Barrado, A. C. M. Correia
Context. Atmospheric and dynamical processes are thought to play a major role in shaping the distribution of close-in exoplanets. A striking feature of such distribution is the Neptunian desert, a dearth of Neptunes on the shortest-period orbits.Aims. We aimed to define the boundaries of the Neptunian desert and study its transition into the savanna, a moderately populated region at larger orbital distances. Our goal was to acquire new insight into the processes that carved out the Neptunian landscape, and to provide the exoplanet community with a framework for conducting studies on planet formation and evolution.Methods. We built a sample of planets and candidates based on the Kepler DR25 catalogue and weighed it according to the transit and detection probabilities. We then used the corrected distribution to study occurrences across the period and period-radius spaces. Results. We delimited the Neptunian desert as the close-in region of the period-radius space with no planets at a 3σ level, and provide the community with simple, ready-to-use approximate boundaries. We identified an overdensity of planets separating the Neptunian desert from the savanna (3.2 days ⪅ Porb ⪅ 5.7 days) that stands out at a 4.7σ level above the desert and at a 3.5σ level above the savanna, which we propose to call the Neptunian ridge. The period range of the ridge matches that of the well-known hot Jupiter pileup (≃3–5 days), which suggests that similar evolutionary processes might act on both populations. We find that the occurrence fraction between the pileup and warm Jupiters (ƒpileup/warm = 5.3 ± 1.1) is about twice that between the Neptunian ridge and savanna (ƒridge/savanna = 2.7 ± 0.5). This indicates either that the processes that drive or maintain planets in the overdensity are more efficient for Jupiters, or that the processes that drive or maintain planets in the warm region are more efficient for Neptunes.Conclusions. Our revised landscape supports a previous hypothesis that a fraction of Neptunes were brought to the edge of the desert (i.e. the newly identified ridge) through high-eccentricity tidal migration (HEM) late in their life, surviving the evaporation that eroded Neptunes having arrived earlier in the desert. The ridge thus appears as a true physical feature illustrating the interplay between photoevaporation and HEM, providing further evidence of their role in shaping the distribution of close-in Neptunes.
{"title":"Mapping the exo-Neptunian landscape","authors":"A. Castro-González, V. Bourrier, J. Lillo-Box, J.-B. Delisle, D. J. Armstrong, D. Barrado, A. C. M. Correia","doi":"10.1051/0004-6361/202450957","DOIUrl":"https://doi.org/10.1051/0004-6361/202450957","url":null,"abstract":"<i>Context<i/>. Atmospheric and dynamical processes are thought to play a major role in shaping the distribution of close-in exoplanets. A striking feature of such distribution is the Neptunian desert, a dearth of Neptunes on the shortest-period orbits.<i>Aims<i/>. We aimed to define the boundaries of the Neptunian desert and study its transition into the savanna, a moderately populated region at larger orbital distances. Our goal was to acquire new insight into the processes that carved out the Neptunian landscape, and to provide the exoplanet community with a framework for conducting studies on planet formation and evolution.<i>Methods<i/>. We built a sample of planets and candidates based on the <i>Kepler<i/> DR25 catalogue and weighed it according to the transit and detection probabilities. We then used the corrected distribution to study occurrences across the period and period-radius spaces. <i>Results<i/>. We delimited the Neptunian desert as the close-in region of the period-radius space with no planets at a 3<i>σ<i/> level, and provide the community with simple, ready-to-use approximate boundaries. We identified an overdensity of planets separating the Neptunian desert from the savanna (3.2 days ⪅ <i>P<i/><sub>orb<sub/> ⪅ 5.7 days) that stands out at a 4.7σ level above the desert and at a 3.5σ level above the savanna, which we propose to call the Neptunian ridge. The period range of the ridge matches that of the well-known hot Jupiter pileup (≃3–5 days), which suggests that similar evolutionary processes might act on both populations. We find that the occurrence fraction between the pileup and warm Jupiters (ƒ<sub>pileup/warm<sub/> = 5.3 ± 1.1) is about twice that between the Neptunian ridge and savanna (ƒ<sub>ridge/savanna<sub/> = 2.7 ± 0.5). This indicates either that the processes that drive or maintain planets in the overdensity are more efficient for Jupiters, or that the processes that drive or maintain planets in the warm region are more efficient for Neptunes.<i>Conclusions<i/>. Our revised landscape supports a previous hypothesis that a fraction of Neptunes were brought to the edge of the desert (i.e. the newly identified ridge) through high-eccentricity tidal migration (HEM) late in their life, surviving the evaporation that eroded Neptunes having arrived earlier in the desert. The ridge thus appears as a true physical feature illustrating the interplay between photoevaporation and HEM, providing further evidence of their role in shaping the distribution of close-in Neptunes.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142236164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1051/0004-6361/202451299
A. Dutrey, E. Chapillon, S. Guilloteau, Y. W. Tang, A. Boccaletti, L. Bouscasse, T. Collin-Dufresne, E. Di Folco, A. Fuente, V. Piétu, P. Rivière-Marichalar, D. Semenov
Context. Sulfur monoxide (SO) is known to be a good shock tracer in molecular clouds and protostar environments, but its abundance is difficult to reproduce, even with state-of-the-art astrochemical models.Aims. We investigate the properties of the observed SO emission in the protoplanetary disk of AB Auriga, a Herbig Ae star of 2.4 M⊙ in mass, located at 156 pc. The AB Aur system is unique because it exhibits a dust trap and at least one young putative planet orbiting at about 30 au from the central star.Methods. We reduced ALMA archival data (projects 2019.1.00579.S, 2021.1.00690.S, and 2021.1.01216.S) and analyzed the three detected SO lines (SO 65 − 54, 67 − 56 and 56 − 45). We also used C17O and C18O 2–1 data to complement the interpretation of the SO data.Results. For the three SO lines, the maximum SO emission in the ring is not located in the dust trap. Moreover, the inner radius of the SO ring is significantly larger than the CO emission inner radius, ∼160 au versus ∼90 au. The SO emission traces gas located in part beyond the dust ring. This emission likely originates from shocks at the interface of the outer spirals, observed in CO and scattered light emission, as well as those in the molecular and dust ring. Also, SO is detected within the cavity, at a radius of ∼20 − 30 au and with a rotation velocity compatible with the protoplanet P1. We speculate that this SO emission originates from accretion shocks onto the circumplanetary disk of the putative protoplanet P1.Conclusions. These observations confirm that SO is a good tracer of shocks in protoplanetary disks and could serve as a powerful new tool for detecting embedded (proto)planets.
背景。众所周知，一氧化硫（SO）是分子云和原初星环境中一种很好的冲击示踪剂，但即使使用最先进的天体化学模型也很难再现其丰度。我们研究了在 AB Auriga 星的原行星盘中观测到的 SO 发射的性质，AB Auriga 星是一颗质量为 2.4 M⊙的 Herbig Ae 星，位于 156 pc 处。AB Aur星系是一个独特的星系，因为它有一个尘埃陷阱，至少有一颗年轻的假定行星在距离中心恒星约30 au处运行。我们缩减了ALMA档案数据（项目：2019.1.00579.S、2021.1.00690.S和2021.1.01216.S），并分析了检测到的三条SO线（SO 65 - 54、67 - 56和56 - 45）。我们还使用了 C17O 和 C18O 2-1 数据来补充解释 SO 数据。对于三条 SO 线来说，环中的最大 SO 发射并不位于尘埃捕获器中。此外，SO环的内半径明显大于CO发射的内半径，分别为160au和90au。SO 辐射追踪的气体部分位于尘埃环之外。这种发射很可能来自外螺旋界面的冲击，在 CO 和散射光发射以及分子环和尘埃环中都能观测到。此外，我们还在空腔内检测到了 SO，其半径为 20 - 30 au，旋转速度与原行星 P1 相符。我们推测，这种 SO 发射源于对推定原行星 P1 的环行星盘的吸积冲击。这些观测结果证实，SO 是原行星盘中冲击的良好示踪剂，可以作为探测嵌入式（原）行星的强大新工具。
{"title":"Sulfur monoxide (SO) as a shock tracer in protoplanetary disks: Case of AB Aurigae","authors":"A. Dutrey, E. Chapillon, S. Guilloteau, Y. W. Tang, A. Boccaletti, L. Bouscasse, T. Collin-Dufresne, E. Di Folco, A. Fuente, V. Piétu, P. Rivière-Marichalar, D. Semenov","doi":"10.1051/0004-6361/202451299","DOIUrl":"https://doi.org/10.1051/0004-6361/202451299","url":null,"abstract":"<i>Context.<i/> Sulfur monoxide (SO) is known to be a good shock tracer in molecular clouds and protostar environments, but its abundance is difficult to reproduce, even with state-of-the-art astrochemical models.<i>Aims.<i/> We investigate the properties of the observed SO emission in the protoplanetary disk of AB Auriga, a Herbig Ae star of 2.4 M<sub>⊙<sub/> in mass, located at 156 pc. The AB Aur system is unique because it exhibits a dust trap and at least one young putative planet orbiting at about 30 au from the central star.<i>Methods.<i/> We reduced ALMA archival data (projects 2019.1.00579.S, 2021.1.00690.S, and 2021.1.01216.S) and analyzed the three detected SO lines (SO 6<sub>5<sub/> − 5<sub>4<sub/>, 6<sub>7<sub/> − 5<sub>6<sub/> and 5<sub>6<sub/> − 4<sub>5<sub/>). We also used C<sup>17<sup/>O and C<sup>18<sup/>O 2–1 data to complement the interpretation of the SO data.<i>Results.<i/> For the three SO lines, the maximum SO emission in the ring is not located in the dust trap. Moreover, the inner radius of the SO ring is significantly larger than the CO emission inner radius, ∼160 au versus ∼90 au. The SO emission traces gas located in part beyond the dust ring. This emission likely originates from shocks at the interface of the outer spirals, observed in CO and scattered light emission, as well as those in the molecular and dust ring. Also, SO is detected within the cavity, at a radius of ∼20 − 30 au and with a rotation velocity compatible with the protoplanet P1. We speculate that this SO emission originates from accretion shocks onto the circumplanetary disk of the putative protoplanet P1.<i>Conclusions.<i/> These observations confirm that SO is a good tracer of shocks in protoplanetary disks and could serve as a powerful new tool for detecting embedded (proto)planets.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142236166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1051/0004-6361/202451398
J. Lillo-Box, D. W. Latham, K. A. Collins, D. J. Armstrong, D. Gandolfi, E. L. N. Jensen, A. Castro-González, O. Balsalobre-Ruza, B. Montesinos, S. G. Sousa, J. Aceituno, R. P. Schwarz, N. Narita, A. Fukui, J. Cabrera, A. Hadjigeorghiou, M. Kuzuhara, T. Hirano, M. Fridlund, A. P. Hatzes, O. Barragán, N. M. Batalha
Context. The transit technique has been very efficient over the past decades in detecting planet-candidate signals. The so-called statistical validation approach has become a popular way of verifying a candidate’s planetary nature. However, the incomplete consideration of false-positive scenarios and data quality can lead to misinterpretation of the results.Aims. In this work, we revise the planetary status of K2-399 b, a validated planet with an estimated false-positive probability of 0.078% located in the middle of the so-called Neptunian desert, and hence a potential key target for atmospheric prospects.Methods. We used radial velocity data from the CARMENES, HARPS, and TRES spectrographs, as well as ground-based multiband transit photometry provided by LCOGT MuSCAT3 and broad band photometry to test the planetary scenario.Results. Our analysis of the available data does not support the existence of this (otherwise key) planet, and instead points to a scenario composed of an early G-dwarf orbited –with a period of a days– by a pair of eclipsing M-dwarfs (hence a hierarchical eclipsing binary) likely in the mid-type domain. We thus demote K2-399 b as a planet.Conclusions. We conclude that the validation process, while very useful to prioritize follow-up efforts, must always be conducted with careful attention to data quality while ensuring that all possible scenarios have been properly tested to get reliable results. We also encourage developers of validation algorithms to ensure the accuracy of a priori probabilities for different stellar scenarios that can lead to this kind of false validation. We further encourage the use of follow-up observations when possible (such as radial velocity and/or multiband light curves) to confirm the planetary nature of detected transiting signals rather than only relying on validation tools.
背景过去几十年来，凌日技术在探测行星候选信号方面一直非常有效。所谓的统计验证方法已成为验证候选行星性质的常用方法。在这项工作中，我们对K2-399 b的行星状态进行了修正。K2-399 b是一颗经过验证的行星，假阳性概率估计为0.078%，位于所谓的海王星沙漠中央，因此是大气前景的潜在关键目标。我们使用了来自CARMENES、HARPS和TRES光谱仪的径向速度数据，以及LCOGT MuSCAT3提供的地基多波段凌日光度测量数据和宽波段光度测量数据来检验行星方案。我们对现有数据的分析并不支持这颗行星（否则就是关键行星）的存在，而是指出了一个由早期G矮星（周期为一天）和一对可能处于中型领域的食M矮星（因此是一个分级食双星）组成的方案。因此，我们将 K2-399 b 降级为行星。我们的结论是，虽然验证过程对于确定后续工作的优先次序非常有用，但在进行验证时必须始终认真关注数据质量，同时确保所有可能的情况都经过了适当的测试，以获得可靠的结果。我们还鼓励验证算法的开发者确保不同恒星情况下的先验概率的准确性，因为这种先验概率可能导致错误验证。我们还鼓励在可能的情况下利用后续观测（如径向速度和/或多波段光曲线）来确认所探测到的凌星信号的行星性质，而不是仅仅依赖于验证工具。
{"title":"K2-399 b is not a planet","authors":"J. Lillo-Box, D. W. Latham, K. A. Collins, D. J. Armstrong, D. Gandolfi, E. L. N. Jensen, A. Castro-González, O. Balsalobre-Ruza, B. Montesinos, S. G. Sousa, J. Aceituno, R. P. Schwarz, N. Narita, A. Fukui, J. Cabrera, A. Hadjigeorghiou, M. Kuzuhara, T. Hirano, M. Fridlund, A. P. Hatzes, O. Barragán, N. M. Batalha","doi":"10.1051/0004-6361/202451398","DOIUrl":"https://doi.org/10.1051/0004-6361/202451398","url":null,"abstract":"<i>Context.<i/> The transit technique has been very efficient over the past decades in detecting planet-candidate signals. The so-called statistical validation approach has become a popular way of verifying a candidate’s planetary nature. However, the incomplete consideration of false-positive scenarios and data quality can lead to misinterpretation of the results.<i>Aims.<i/> In this work, we revise the planetary status of K2-399 b, a validated planet with an estimated false-positive probability of 0.078% located in the middle of the so-called Neptunian desert, and hence a potential key target for atmospheric prospects.<i>Methods.<i/> We used radial velocity data from the CARMENES, HARPS, and TRES spectrographs, as well as ground-based multiband transit photometry provided by LCOGT MuSCAT3 and broad band photometry to test the planetary scenario.<i>Results.<i/> Our analysis of the available data does not support the existence of this (otherwise key) planet, and instead points to a scenario composed of an early G-dwarf orbited –with a period of a days– by a pair of eclipsing M-dwarfs (hence a hierarchical eclipsing binary) likely in the mid-type domain. We thus demote K2-399 b as a planet.<i>Conclusions.<i/> We conclude that the validation process, while very useful to prioritize follow-up efforts, must always be conducted with careful attention to data quality while ensuring that all possible scenarios have been properly tested to get reliable results. We also encourage developers of validation algorithms to ensure the accuracy of a priori probabilities for different stellar scenarios that can lead to this kind of false validation. We further encourage the use of follow-up observations when possible (such as radial velocity and/or multiband light curves) to confirm the planetary nature of detected transiting signals rather than only relying on validation tools.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142236168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1051/0004-6361/202449470
M. Polkas, S. Bonoli, E. Bortolas, D. Izquierdo-Villalba, A. Sesana, L. Broggi, N. Hoyer, D. Spinoso
Stars can be ripped apart by tidal forces in the vicinity of a massive black hole (MBH), causing luminous flares known as tidal disruption events (TDEs). These events could be contributing to the mass growth of intermediate-mass MBHs. New samples from transient surveys can provide useful information on this unexplored growth channel. This work aims to study the demographics of TDEs by modeling the coevolution of MBHs and their galactic environments in a cosmological framework. We use the semianalytic galaxy formation model L-Galaxies BH, which follows the evolution of galaxies as well as of MBHs, including multiple scenarios for MBH seeds and growth, spin evolution, and binary MBH dynamics. We associated time-dependent TDE rates with each MBH depending on the stellar environment, following the solutions to the 1D Fokker Planck equation solved with PHASEFLOW. Our model produces volumetric rates that are in agreement with the latest optical and previous X-ray samples. This agreement requires a high occupation fraction of nuclear star clusters with MBHs since these star reservoirs host the majority of TDEs at all mass regimes. We predict that TDE rates are an increasing function of MBH mass up to ∼105.5M⊙, beyond which the distribution flattens and eventually drops for > 107M⊙. In general, volumetric rates are predicted to be redshift independent at z < 1. We discuss how the spin distribution of MBHs around the event horizon suppression can be constrained via TDE rates and the average contribution of TDEs to the MBH growth. In our work, the majority of low-mass galaxies host nuclear star clusters that have their loss-cone depleted by z = 0, explaining why TDEs are rare in these systems. This highlights how essential time-dependent TDE rates are for any model to be in good agreement with observations at all mass regimes.
{"title":"Demographics of tidal disruption events with L-Galaxies","authors":"M. Polkas, S. Bonoli, E. Bortolas, D. Izquierdo-Villalba, A. Sesana, L. Broggi, N. Hoyer, D. Spinoso","doi":"10.1051/0004-6361/202449470","DOIUrl":"https://doi.org/10.1051/0004-6361/202449470","url":null,"abstract":"Stars can be ripped apart by tidal forces in the vicinity of a massive black hole (MBH), causing luminous flares known as tidal disruption events (TDEs). These events could be contributing to the mass growth of intermediate-mass MBHs. New samples from transient surveys can provide useful information on this unexplored growth channel. This work aims to study the demographics of TDEs by modeling the coevolution of MBHs and their galactic environments in a cosmological framework. We use the semianalytic galaxy formation model <i>L-Galaxies<i/> BH, which follows the evolution of galaxies as well as of MBHs, including multiple scenarios for MBH seeds and growth, spin evolution, and binary MBH dynamics. We associated time-dependent TDE rates with each MBH depending on the stellar environment, following the solutions to the 1D Fokker Planck equation solved with PHASEFLOW. Our model produces volumetric rates that are in agreement with the latest optical and previous X-ray samples. This agreement requires a high occupation fraction of nuclear star clusters with MBHs since these star reservoirs host the majority of TDEs at all mass regimes. We predict that TDE rates are an increasing function of MBH mass up to ∼10<sup>5.5<sup/> <i>M<i/><sub>⊙<sub/>, beyond which the distribution flattens and eventually drops for > 10<sup>7<sup/> <i>M<i/><sub>⊙<sub/>. In general, volumetric rates are predicted to be redshift independent at <i>z<i/> < 1. We discuss how the spin distribution of MBHs around the event horizon suppression can be constrained via TDE rates and the average contribution of TDEs to the MBH growth. In our work, the majority of low-mass galaxies host nuclear star clusters that have their loss-cone depleted by <i>z<i/> = 0, explaining why TDEs are rare in these systems. This highlights how essential time-dependent TDE rates are for any model to be in good agreement with observations at all mass regimes.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142234280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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