Publications of the Astronomical Society of Australia最新文献

{"title":"Modelling repetition in zDM: a single population of repeating fast radio bursts can explain CHIME data","authors":"C.W. James","doi":"10.1017/pasa.2023.51","DOIUrl":"https://doi.org/10.1017/pasa.2023.51","url":null,"abstract":"Abstract Regardless of whether or not all fast radio bursts (FRBs) repeat, those that do form a population with a distribution of rates. This work considers a power-law model of this population, with rate distribution Φ r ∼ R γ r between R min and R max . The zDM code is used to model the probability of detecting this population as either apparently once-off or repeat events as a function of redshift, z , and dispersion measure, DM. I demonstrate that in the nearby Universe, repeating sources can contribute significantly to the total burst rate. This causes an apparent deficit in the total number of observed sources (once-off and repeaters) relative to the distant Universe that will cause a bias in FRB population models. Thus instruments with long exposure times should explicitly take repetition into account when fitting the FRB population. I then fit data from The Canadian Hydrogen Intensity Mapping Experiment (CHIME). The relative number of repeat and apparently once-off FRBs, and their DM, declination, and burst rate distributions, can be well-explained by 50–100% of CHIME single FRBs being due to repeaters, with R max > 0.75 day –1 above 10 39 erg, and This result is surprisingly consistent with follow-up studies of FRBs detected by the Australian Square Kilometre Array Pathfinder (ASKAP). Thus the evidence suggests that CHIME and ASKAP view the same repeating FRB population, which is responsible not just for repeating FRBs, but the majority of apparently once-off bursts. For greater quantitative accuracy, non-Poissonian arrival times, second-order effects in the CHIME response, and a simultaneous fit to the total FRB population parameters, should be treated in more detail in future studies.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134908928","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":"Radio Galaxy Zoo: Tagging Radio Subjects using Text","authors":"Dawei Chen, Vinay Kerai, Matthew J. Alger, O. Ivy Wong, Cheng Soon Ong","doi":"10.1017/pasa.2023.50","DOIUrl":"https://doi.org/10.1017/pasa.2023.50","url":null,"abstract":"Abstract RadioTalk is a communication platform that enabled members of the Radio Galaxy Zoo (RGZ) citizen science project to engage in discussion threads and provide further descriptions of the radio subjects they were observing in the form of tags and comments. It contains a wealth of auxiliary information which is useful for the morphology identification of complex and extended radio sources. In this paper, we present this new dataset, and for the first time in radio astronomy, we combine text and images to automatically classify radio galaxies using a multi-modal learning approach. We found incorporating text features improved classification performance which demonstrates that text annotations are rare but valuable sources of information for classifying astronomical sources, and suggests the importance of exploiting multi-modal information in future citizen science projects. We also discovered over 10,000 new radio sources beyond the RGZ-DR1 catalogue in this dataset.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136113861","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":"The Dawes Review 11: From young to old: The evolutionary path of Pulsar Wind Nebulae – CORRIGENDUM","authors":"B. Olmi, N. Bucciantini","doi":"10.1017/pasa.2023.41","DOIUrl":"https://doi.org/10.1017/pasa.2023.41","url":null,"abstract":"11","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2023-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82534737","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":"The Mopra Southern Galactic Plane CO Survey – data release 4– complete survey","authors":"K. Cubuk, M. Burton, C. Braiding, G. Wong, G. Rowell, N. Maxted, D. Eden, R. Z. E. Alsaberi, R. Blackwell, R. Enokiya, K. Feijen, M. Filipović, M. Freeman, S. Fujita, M. Ghavam, B. Gunay, B. Indermuehle, K. Hayashi, M. Kohno, T. Nagaya, A. Nishimura, K. Okawa, D. Rebolledo, D. Romano, H. Sano, C. Snoswell, N. Tothill, K. Tsuge, F. Voisin, Y. Yamane, S. Yoshiike","doi":"10.1017/pasa.2023.44","DOIUrl":"https://doi.org/10.1017/pasa.2023.44","url":null,"abstract":"Abstract We present observations of the Mopra carbon monoxide (CO) survey of the Southern Galactic Plane, covering Galactic longitudes spanning \u0000$l = 250^{circ}$\u0000 ( \u0000$-110^{circ}$\u0000 ) to \u0000$l = 355^{circ}$\u0000 ( \u0000$-5^{circ}$\u0000 ), with a latitudinal coverage of at least \u0000$|b|<1^circ$\u0000 , totalling an area of \u0000$>$\u0000 210 deg \u0000$^{2}$\u0000 . These data have been taken at 0.6 arcmin spatial resolution and 0.1 km s \u0000$^{-1}$\u0000 spectral resolution, providing an unprecedented view of the molecular gas clouds of the Southern Galactic Plane in the 109–115 GHz \u0000$J = 1-0$\u0000 transitions of \u0000$^{12}$\u0000 CO, \u0000$^{13}$\u0000 CO, C \u0000$^{18}$\u0000 O, and C \u0000$^{17}$\u0000 O.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75917933","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":"A novel approach for variable star classification based on imbalanced learning","authors":"Jingyi Zhang, Yanxia Zhang, Zihan Kang, Changhua Li, Yihan Tao, Yongheng Zhao, Xue-bing Wu","doi":"10.1017/pasa.2023.35","DOIUrl":"https://doi.org/10.1017/pasa.2023.35","url":null,"abstract":"Abstract The advent of time-domain sky surveys has generated a vast amount of light variation data, enabling astronomers to investigate variable stars with large-scale samples. However, this also poses new opportunities and challenges for the time-domain research. In this paper, we focus on the classification of variable stars from the Catalina Surveys Data Release 2 and propose an imbalanced learning classifier based on Self-paced Ensemble (SPE) method. Compared with the work of Hosenie et al. (2020), our approach significantly enhances the classification Recall of Blazhko RR Lyrae stars from 12% to 85%, mixed-mode RR Lyrae variables from 29% to 64%, detached binaries from 68% to 97%, and LPV from 87% to 99%. SPE demonstrates a rather good performance on most of the variable classes except RRab, RRc, and contact and semi-detached binary. Moreover, the results suggest that SPE tends to target the minority classes of objects, while Random Forest is more effective in finding the majority classes. To balance the overall classification accuracy, we construct a Voting Classifier that combines the strengths of SPE and Random Forest. The results show that the Voting Classifier can achieve a balanced performance across all classes with minimal loss of accuracy. In summary, the SPE algorithm and Voting Classifier are superior to traditional machine learning methods and can be well applied to classify the periodic variable stars. This paper contributes to the current research on imbalanced learning in astronomy and can also be extended to the time-domain data of other larger sky survey projects (LSST, etc.).","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75239898","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":"Statistical analysis of kicked black holes from TNG300 simulation","authors":"M. Smole, M. Micic","doi":"10.1017/pasa.2023.45","DOIUrl":"https://doi.org/10.1017/pasa.2023.45","url":null,"abstract":"Abstract Asymmetric emission of gravitational waves during mergers of black holes (BHs) produces a recoil kick, which can set a newly formed BH on a bound orbit around the centre of its host galaxy, or even completely eject it. To study this population of recoiling BHs we extract properties of galaxies with merging BHs from Illustris TNG300 simulation and then employ both analytical and numerical techniques to model unresolved process of BH recoil. This comparative analysis between analytical and numerical models shows that, on cosmological scales, numerically modelled recoiling BHs have a higher escape probability and predict a greater number of offset active galactic nuclei (AGN). BH escaped probability \u0000$>$\u0000 40% is expected in 25 \u0000$%$\u0000 of merger remnants in numerical models, compared to 8 \u0000$%$\u0000 in analytical models. At the same time, the predicted number of offset AGN at separations \u0000${>}5$\u0000 kpc changes from 58 \u0000$%$\u0000 for numerical models to 3 \u0000$%$\u0000 for analytical models. Since BH ejections in major merger remnants occur in non-virialised systems, static analytical models cannot provide an accurate description. Thus we argue that numerical models should be used to estimate the expected number density of escaped BHs and offset AGN.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89659003","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":"Evolved galaxies in high-density environments across 2.0 ≤ z < 4.2 using the ZFOURGE survey","authors":"Georgia R. Hartzenberg, M. Cowley, A. Hopkins, R. Allen","doi":"10.1017/pasa.2023.42","DOIUrl":"https://doi.org/10.1017/pasa.2023.42","url":null,"abstract":"Abstract To explore the role environment plays in influencing galaxy evolution at high redshifts, we study \u0000$2.0leq z<4.2$\u0000 environments using the FourStar Galaxy Evolution (ZFOURGE) survey. Using galaxies from the COSMOS legacy field with \u0000${rm log(M_{*}/M_{odot})}geq9.5$\u0000 , we use a seventh nearest neighbour density estimator to quantify galaxy environment, dividing this into bins of low-, intermediate-, and high-density. We discover new high-density environment candidates across \u0000$2.0leq z<2.4$\u0000 and \u0000$3.1leq z<4.2$\u0000 . We analyse the quiescent fraction, stellar mass and specific star formation rate (sSFR) of our galaxies to understand how these vary with redshift and environment. Our results reveal that, across \u0000$2.0leq z<2.4$\u0000 , the high-density environments are the most significant regions, which consist of elevated quiescent fractions, \u0000${rm log(M_{*}/M_{odot})}geq10.2$\u0000 massive galaxies and suppressed star formation activity. At \u0000$3.1leq z<4.2$\u0000 , we find that high-density regions consist of elevated stellar masses but require more complete samples of quiescent and sSFR data to study the effects of environment in more detail at these higher redshifts. Overall, our results suggest that well-evolved, passive galaxies are already in place in high-density environments at \u0000$zsim2.4$\u0000 , and that the Butcher–Oemler effect and SFR-density relation may not reverse towards higher redshifts as previously thought.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73016809","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":"Deep learning for morphological identification of extended radio galaxies using weak labels","authors":"N. Gupta, Zeeshan Hayder, R. Norris, M. Huynh, L. Petersson, X. R. Wang, H. Andernach, B. Koribalski, M. Yew, E. Crawford","doi":"10.1017/pasa.2023.46","DOIUrl":"https://doi.org/10.1017/pasa.2023.46","url":null,"abstract":"Abstract The present work discusses the use of a weakly-supervised deep learning algorithm that reduces the cost of labelling pixel-level masks for complex radio galaxies with multiple components. The algorithm is trained on weak class-level labels of radio galaxies to get class activation maps (CAMs). The CAMs are further refined using an inter-pixel relations network (IRNet) to get instance segmentation masks over radio galaxies and the positions of their infrared hosts. We use data from the Australian Square Kilometre Array Pathfinder (ASKAP) telescope, specifically the Evolutionary Map of the Universe (EMU) Pilot Survey, which covered a sky area of 270 square degrees with an RMS sensitivity of 25–35 \u0000$mu$\u0000 Jy beam \u0000$^{-1}$\u0000 . We demonstrate that weakly-supervised deep learning algorithms can achieve high accuracy in predicting pixel-level information, including masks for the extended radio emission encapsulating all galaxy components and the positions of the infrared host galaxies. We evaluate the performance of our method using mean Average Precision (mAP) across multiple classes at a standard intersection over union (IoU) threshold of 0.5. We show that the model achieves a mAP \u0000$_{50}$\u0000 of 67.5% and 76.8% for radio masks and infrared host positions, respectively. The network architecture can be found at the following link: https://github.com/Nikhel1/Gal-CAM","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74401057","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":"Turbulence measurements in the neutral ISM from Hi-21 cm emission–absorption spectra","authors":"Atanu Koley","doi":"10.1017/pasa.2023.43","DOIUrl":"https://doi.org/10.1017/pasa.2023.43","url":null,"abstract":"Abstract We study the correlation between the non-thermal velocity dispersion ( \u0000$sigma_{nth}$\u0000 ) and the length scale (L) in the neutral interstellar medium (ISM) using a large number of Hi gas components taken from various published Hi surveys and previous Hi studies. We notice that above the length-scale (L) of 0.40 pc, there is a power-law relationship between \u0000$sigma_{nth}$\u0000 and L. However, below 0.40 pc, there is a break in the power law, where \u0000$sigma_{nth}$\u0000 is not significantly correlated with L. It has been observed from the Markov chain Monte Carlo (MCMC) method that for the dataset of L \u0000$gt$\u0000 0.40 pc, the most probable values of intensity (A) and power-law index (p) are 1.14 and 0.55, respectively. Result of p suggests that the power law is steeper than the standard Kolmogorov law of turbulence. This is due to the dominance of clouds in the cold neutral medium. This is even more clear when we separate the clouds into two categories: one for L is \u0000$gt$\u0000 0.40 pc and the kinetic temperature ( \u0000$T_{k}$\u0000 ) is \u0000$lt$\u0000 250 K, which are in the cold neutral medium (CNM) and for other one where L is \u0000$gt$\u0000 0.40 pc and \u0000$T_{k}$\u0000 is between 250 and 5 000 K, which are in the thermally unstable phase (UNM). Most probable values of A and p are 1.14 and 0.67, respectively, in the CNM phase and 1.01 and 0.52, respectively, in the UNM phase. A greater number of data points is effective for the UNM phase in constructing a more accurate estimate of A and p, since most of the clouds in the UNM phase lie below 500 K. However, from the value of p in the CNM phase, it appears that there is a significant difference from the Kolmogorov scaling, which can be attributed to a shock-dominated medium.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86071519","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":"Probing the consistency of cosmological contours for supernova cosmology","authors":"P. Armstrong, H. Qu, D. Brout, T. Davis, R. K. A. G. Kim, C. Lidman, M. Sako, B. Observatory, T. D. O. Astronomy, Astrophysics, A. N. University, Act 2601, Australia, D. Physics, Astronomy, U. Pennsylvania, Philadelphia, PA 19104, USA., D. Astronomy, Boston University, 725 Commonwealth Ave., Boston, MA 02215, S. O. Mathematics, Physics, The University of Queensland, Brisbane, Qld 4072, Kavli Institute for Cosmological Physics, U. Chicago, Chicago, IL 60637, P. Division, L. B. N. Laboratory, Berkeley, CA 94720, Centre for Gravitational Astrophysics, College of Materials Science, The Australian National University, Australia. School of Science, Canberra, The Arc Centre of Excellence for All-Sky Astrophysics Dimensions","doi":"10.1017/pasa.2023.40","DOIUrl":"https://doi.org/10.1017/pasa.2023.40","url":null,"abstract":"Abstract As the scale of cosmological surveys increases, so does the complexity in the analyses. This complexity can often make it difficult to derive the underlying principles, necessitating statistically rigorous testing to ensure the results of an analysis are consistent and reasonable. This is particularly important in multi-probe cosmological analyses like those used in the Dark Energy Survey (DES) and the upcoming Legacy Survey of Space and Time, where accurate uncertainties are vital. In this paper, we present a statistically rigorous method to test the consistency of contours produced in these analyses and apply this method to the Pippin cosmological pipeline used for type Ia supernova cosmology with the DES. We make use of the Neyman construction, a frequentist methodology that leverages extensive simulations to calculate confidence intervals, to perform this consistency check. A true Neyman construction is too computationally expensive for supernova cosmology, so we develop a method for approximating a Neyman construction with far fewer simulations. We find that for a simulated dataset, the 68% contour reported by the Pippin pipeline and the 68% confidence region produced by our approximate Neyman construction differ by less than a percent near the input cosmology; however, they show more significant differences far from the input cosmology, with a maximal difference of 0.05 in \u0000$Omega_{M}$\u0000 and 0.07 in w. This divergence is most impactful for analyses of cosmological tensions, but its impact is mitigated when combining supernovae with other cross-cutting cosmological probes, such as the cosmic microwave background.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80937353","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}