Publications of the Astronomical Society of Australia最新文献

{"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":null,"pages":null},"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}

{"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":null,"pages":null},"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}

{"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":null,"pages":null},"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}

{"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&gt;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":null,"pages":null},"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}

{"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":null,"pages":null},"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}

{"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&amp;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":null,"pages":null},"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}

{"title":"Predicting the Scaling Relations between the Dark Matter Halo Mass and Observables from Generalised Profiles II: Intracluster Gas Emission","authors":"A. Sullivan, C. Power, C. Bottrell, A. Robotham, S. Shabala","doi":"10.1017/pasa.2024.24","DOIUrl":"https://doi.org/10.1017/pasa.2024.24","url":null,"abstract":"We investigate the connection between a cluster’s structural configuration and observable measures of its gas emission that can be obtained in X-ray and Sunyaev-Zeldovich (SZ) surveys. We present an analytic model for the intracluster gas density profile: parameterised by the dark matter halo’s inner logarithmic density slope, <jats:italic>α</jats:italic>, the concentration, <jats:italic>c</jats:italic>, the gas profile’s inner logarithmic density slope, <jats:italic>ε</jats:italic>, the dilution, <jats:italic>d</jats:italic>, and the gas fraction, η, normalised to cosmological content. We predict four probes of the gas emission: the emission-weighted, <jats:italic>T</jats:italic><jats:sub>X</jats:sub>, and mean gas mass-weighted, <jats:italic>T</jats:italic><jats:sub>mg</jats:sub>, temperatures, and the spherically, <jats:italic>Y</jats:italic><jats:sub>sph</jats:sub>, and cylindrically, <jats:italic>Y</jats:italic><jats:sub>cyl</jats:sub>, integrated Compton parameters. Over a parameter space of clusters, we constrain the X-ray temperature scaling relations, <jats:italic>M</jats:italic><jats:sub>200</jats:sub> – <jats:italic>T</jats:italic><jats:sub>X</jats:sub> and <jats:italic>M</jats:italic><jats:sub>500</jats:sub> – <jats:italic>T</jats:italic><jats:sub>X</jats:sub>, within 57.3% and 41.6%, and <jats:italic>M</jats:italic><jats:sub>200</jats:sub> – <jats:italic>T</jats:italic><jats:sub>mg</jats:sub> and <jats:italic>M</jats:italic><jats:sub>500</jats:sub> – <jats:italic>T</jats:italic><jats:sub>mg</jats:sub>, within 25.7% and 7.0%, all respectively. When excising the cluster’s core, the <jats:italic>M</jats:italic><jats:sub>200</jats:sub> – <jats:italic>T</jats:italic><jats:sub>X</jats:sub> and <jats:italic>M</jats:italic><jats:sub>500</jats:sub> – <jats:italic>T</jats:italic><jats:sub>X</jats:sub> relations are further constrained, to within 31.3% and 17.1%, respectively. Similarly, we constrain the SZ scaling relations, <jats:italic>M</jats:italic><jats:sub>200</jats:sub> – <jats:italic>Y</jats:italic><jats:sub>sph</jats:sub> and <jats:italic>M</jats:italic><jats:sub>500</jats:sub> – <jats:italic>Y</jats:italic><jats:sub>sph</jats:sub>, within 31.1% and 17.7%, and <jats:italic>M</jats:italic><jats:sub>200</jats:sub> – <jats:italic>Y</jats:italic><jats:sub>cyl</jats:sub> and <jats:italic>M</jats:italic><jats:sub>500</jats:sub> – <jats:italic>Y</jats:italic><jats:sub>cyl</jats:sub>, within 25.2% and 22.0%, all respectively. The temperature observable <jats:italic>T</jats:italic><jats:sub>mg</jats:sub> places the strongest constraint on the halo mass, whilst <jats:italic>T</jats:italic><jats:sub>X</jats:sub> is more sensitive to the parameter space. The SZ constraints are sensitive to the gas fraction, whilst insensitive to the form of the gas profile itself. In all cases, the halo mass is recovered with an uncertainty that suggests the cluster’s structural profiles only contribute a minor uncertainty in its scaling relations.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140313140","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}

{"title":"Fast as Potoroo: Radio Continuum Detection of a Bow-Shock Pulsar Wind Nebula Powered by Pulsar J1638–4713","authors":"Sanja Lazarević, Miroslav D. Filipović, Shi Dai, Roland Kothes, Adeel Ahmad, Rami Z. E. Alsaberi, Joel C. F. Balzan, Luke A. Barnes, William D. Cotton, Philip G. Edwards, Yjan A. Gordon, Frank Haberl, Andrew M. Hopkins, Bärbel S. Koribalski, Denis Leahy, Chandreyee Maitra, Marko Mićić, Gavin Rowell, Manami Sasaki, Nicholas F. H. Tothill, Grazia Umana, Velibor Velović","doi":"10.1017/pasa.2024.13","DOIUrl":"https://doi.org/10.1017/pasa.2024.13","url":null,"abstract":"We report the discovery of a bow-shock pulsar wind nebula (PWN), named Potoroo, and the detection of a young pulsar J1638–4713 that powers the nebula. We present a radio continuum study of the PWN based on 20-cm observations obtained from the Australian Square Kilometre Array Pathfinder (ASKAP) and MeerKAT. PSR J1638–4713 was identified using Parkes radio telescope observations at frequencies above 3 GHz. The pulsar has the second-highest dispersion measure of all known radio pulsars (1553 pc cm<jats:sup>–3</jats:sup>), a spin period of 65.74 ms and a spin-down luminosity of <jats:italic>Ė</jats:italic> = 6.1 × 10<jats:sup>36</jats:sup> erg s<jats:sup>–1</jats:sup>. The PWN has a cometary morphology and one of the greatest projected lengths among all the observed pulsar radio tails, measuring over 21 pc for an assumed distance of 10 kpc. The remarkably long tail and atypically steep radio spectral index are attributed to the interplay of a supernova reverse shock and the PWN. The originating supernova remnant is not known so far. We estimated the pulsar kick velocity to be in the range of 1000 – 2000 <jats:italic>km s</jats:italic><jats:sup>–1</jats:sup> for ages between 23 and 10 kyr. The X-ray counterpart found in <jats:italic>Chandra</jats:italic> data, CXOU J163802.6–471358, shows the same tail morphology as the radio source but is shorter by a factor of 10. The peak of the X-ray emission is offset from the peak of the radio total intensity (Stokes I) emission by approximately 4.7”, but coincides well with circularly polarised (Stokes V) emission. No infrared counterpart was found.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140299695","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}

{"title":"Galaxy spin direction asymmetry in JWST deep fields","authors":"Lior Shamir","doi":"10.1017/pasa.2024.20","DOIUrl":"https://doi.org/10.1017/pasa.2024.20","url":null,"abstract":"The unprecedented imaging power of JWST provides new abilities to observe the shapes of objects in the early Universe in a way that has not been possible before. Recently, JWST acquired a deep field image inside the same field imaged in the past as the HST Ultra Deep Field. Computer-based quantitative analysis of spiral galaxies in that field shows that among 34 galaxies for which their rotation of direction can be determined by the shapes of the arms, 24 rotate clockwise, and just 10 rotate counterclockwise. The one-tailed binomial distribution probability to have asymmetry equal or stronger than the observed asymmetry by chance is ∼0.012. While the analysis is limited by the small size of the data, the observed asymmetry is aligned with all relevant previous large-scale analyses from all premier digital sky surveys, all show a higher number of galaxies rotating clockwise in that part of the sky, and the magnitude of the asymmetry increases as the redshift gets higher. This paper also provides data and analysis to reproduce previous experiments suggesting that the distribution of galaxy rotation in the Universe is random, to show that the exact same data used in these studies in fact show non-random distribution, and in excellent agreement with the results shown here. These findings reinforce consideration of the possibility that the directions of rotation of spiral galaxies as observed from Earth are not necessarily randomly distributed. The explanation can be related to the large-scale structure of the Universe, but can also be related to a possible anomaly in the physics of galaxy rotation.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140299269","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}

{"title":"Angular momentum and energy transport in disc–jet systems. Unravelling the contribution of saturated thermal conduction","authors":"Ghassen Rezgui, Reinhold Preiner","doi":"10.1017/pasa.2024.23","DOIUrl":"https://doi.org/10.1017/pasa.2024.23","url":null,"abstract":"This study builds upon our prior work to further explore and unravel the effects of saturated thermal conduction within a viscous resistive MHD framework on the intricate transport mechanisms of angular momentum and energy in disc-jet systems. We conducted a series of 2.5-dimensional non-relativistic time-dependent numerical simulations using the PLUTO code. Employing a saturation parameter spanning [0.002-0.01], our results are consistent with previous investigations that omitted consideration of thermal conduction, affirming the established understanding that kinetic torque plays a predominant role in governing the total accretion angular momentum, surpassing the magnetic contribution within the disc. At the initial time-steps of our calculations, we find that thermal conduction enhances this kinetic contribution, while concurrently diminishing the effect of magnetic contribution. In contrast to the prevailing influence of kinetic torque within the disc, we also assert the magnetic torque as the primary contributor to the total ejection angular momentum. We further unveil that doubling the saturation parameter leads to bolstering of approximately 23.7% in the integral dominance of magnetic torque compared to kinetic torque within the jet. Our findings reveal that doubling the effect of thermal conduction improves the integral total accretion power by approximately 2%, thereby slightly amplifying the energy content within the system and increasing overall energy output. We underscore that as the local energy dissipation within the disc intensifies, the significance of the enthalpy accretion flux increases at the expense of the jet power. We reveal that increasing the saturation parameter mitigates enthalpy accumulation within the disc, and further restricts the jet’s energy extraction from the disc. This limitation is determined in our analysis through the decrease in the integral ratio between the bipolar jet and liberated power of approximately 13.8%, for twice the strength of the saturation parameter. We identify the Poynting flux as the primary contributor to total jet power, with thermal conduction exerting minimal influence on magnetic contributions. Additionally, we emphasise the integration of jet enthalpy as another significant factor in determining overall jet power, highlighting a distinct correlation between the rise in saturation parameter and heightened enthalpy contribution. Moreover, we observe the promotion of Poynting flux over kinetic flux at advanced time-steps of our simulations, a trend supported by the presence of thermal conduction, which demonstrates an integral increase of approximately 11.2% when considering a doubling of the saturation parameter.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140203086","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}