A. Sullivan, C. Power, C. Bottrell, A. Robotham, S. Shabala
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, α, the concentration, c, the gas profile’s inner logarithmic density slope, ε, the dilution, d, and the gas fraction, η, normalised to cosmological content. We predict four probes of the gas emission: the emission-weighted, TX, and mean gas mass-weighted, Tmg, temperatures, and the spherically, Ysph, and cylindrically, Ycyl, integrated Compton parameters. Over a parameter space of clusters, we constrain the X-ray temperature scaling relations, M200 – TX and M500 – TX, within 57.3% and 41.6%, and M200 – Tmg and M500 – Tmg, within 25.7% and 7.0%, all respectively. When excising the cluster’s core, the M200 – TX and M500 – TX relations are further constrained, to within 31.3% and 17.1%, respectively. Similarly, we constrain the SZ scaling relations, M200 – Ysph and M500 – Ysph, within 31.1% and 17.7%, and M200 – Ycyl and M500 – Ycyl, within 25.2% and 22.0%, all respectively. The temperature observable Tmg places the strongest constraint on the halo mass, whilst TX 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.
{"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":"144 1","pages":""},"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}
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
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–3), a spin period of 65.74 ms and a spin-down luminosity of Ė = 6.1 × 1036 erg s–1. 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 km s–1 for ages between 23 and 10 kyr. The X-ray counterpart found in Chandra 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.
{"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":"17 1","pages":""},"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}
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.
{"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":"183 1","pages":""},"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}
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.
{"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":"11 1","pages":""},"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}
Ran Zhang, Meng Liu, Zhenping Yi, Hao Yuan, Zechao Yang, Yude Bu, Xiaoming Kong, Chenglin Jia, Yuchen Bi, Yusheng Zhang
In large-scale galaxy surveys, particularly deep ground-based photometric studies, galaxy blending was inevitable. Such blending posed a potential primary systematic uncertainty for upcoming surveys. Current deblenders predominantly depended on analytical modeling of galaxy profiles, facing limitations due to inflexible and imprecise models. We presented a novel approach, using a U-net structured Transformer-based network for deblending astronomical images, which we term the CAT-deblender. It was trained using both RGB and the grz-band images, spanning two distinct data formats present in the Dark Energy Camera Legacy Survey (DECaLS) database, including galaxies with diverse morphologies in the training dataset. Our method necessitated only the approximate central coordinates of each target galaxy, sourced from galaxy detection, bypassing assumptions on neighboring source counts. Post-deblending, our RGB images retained a high signal-to-noise peak, consistently showing superior structural similarity against ground truth. For multi-band images, the ellipticity of central galaxies and median reconstruction error for r-band consistently lie within ±0.025 to ±0.25, revealing minimal pixel residuals. In our comparison of deblending capabilities focused on flux recovery, our model showed a mere 1% error in magnitude recovery for quadruply blended galaxies, significantly outperforming SExtractor’s higher error rate of 4.8%. Furthermore, by cross-matching with the publicly accessible overlapping galaxy catalogs from the DECaLS database, we successfully deblended 433 overlapping galaxies. Moreover, we’ve demonstrated effective deblending of 63,733 blended galaxy images, randomly chosen from the DECaLS database.
{"title":"Deblending overlapping galaxies in DECaLS using Transformer-Based algorithm: a method combining multiple bands and data types","authors":"Ran Zhang, Meng Liu, Zhenping Yi, Hao Yuan, Zechao Yang, Yude Bu, Xiaoming Kong, Chenglin Jia, Yuchen Bi, Yusheng Zhang","doi":"10.1017/pasa.2024.16","DOIUrl":"https://doi.org/10.1017/pasa.2024.16","url":null,"abstract":"In large-scale galaxy surveys, particularly deep ground-based photometric studies, galaxy blending was inevitable. Such blending posed a potential primary systematic uncertainty for upcoming surveys. Current deblenders predominantly depended on analytical modeling of galaxy profiles, facing limitations due to inflexible and imprecise models. We presented a novel approach, using a U-net structured Transformer-based network for deblending astronomical images, which we term the <jats:italic>CAT-deblender</jats:italic>. It was trained using both RGB and the <jats:italic>grz</jats:italic>-band images, spanning two distinct data formats present in the Dark Energy Camera Legacy Survey (<jats:italic>DECaLS</jats:italic>) database, including galaxies with diverse morphologies in the training dataset. Our method necessitated only the approximate central coordinates of each target galaxy, sourced from galaxy detection, bypassing assumptions on neighboring source counts. Post-deblending, our RGB images retained a high signal-to-noise peak, consistently showing superior structural similarity against ground truth. For multi-band images, the ellipticity of central galaxies and median reconstruction error for <jats:italic>r</jats:italic>-band consistently lie within ±0.025 to ±0.25, revealing minimal pixel residuals. In our comparison of deblending capabilities focused on flux recovery, our model showed a mere 1% error in magnitude recovery for quadruply blended galaxies, significantly outperforming SExtractor’s higher error rate of 4.8%. Furthermore, by cross-matching with the publicly accessible overlapping galaxy catalogs from the <jats:italic>DECaLS</jats:italic> database, we successfully deblended 433 overlapping galaxies. Moreover, we’ve demonstrated effective deblending of 63,733 blended galaxy images, randomly chosen from the <jats:italic>DECaLS</jats:italic> database.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"25 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140166158","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}
Edward Olex, Alexander Knebe, Noam I. Libeskind, Dmitry I. Makarov, Stefan Gottlöber
We present a new method – called HINORA (HIgh-NOise RANdom SAmple Consensus) – for the identification of regular structures in 3D point distributions. Motivated by the possible existence of the so-called Council of Giants, i.e. a ring of twelve massive galaxies surrounding the Local Group in the Local Sheet with a radius of 3.75 Mpc, we apply HINORA to the Local Volume Galaxy catalogue confirming its existence. When varying the lower limit of K-band luminosity of the galaxy entering the catalogue, we further report on the existence of another ring-like structure in the Local Volume that now contains the MilkyWay and M31. However, this newly found structure is dominated by low-mass (satellite) galaxies. While we here simply present the novel method as well as its first application to observational data, follow-up work using numerical simulations of cosmic structure formation shall shed light into the origin of such regular patterns in the galaxy distribution. Further, the method is equally suited to identify similar (or even different) structures in various kinds of astrophysical data (e.g. locating the actual ‘baryonic-acoustic oscillation spheres’ in galaxy redshift surveys).
我们提出了一种新方法--HINORA（HIgh-NOise RANdom SAmple Consensus）--用于识别三维点分布中的规则结构。受可能存在所谓的 "巨人理事会"（Council of Giants）的启发，我们将 HINORA 应用于本地体积星系目录，证实了它的存在。当改变进入目录的星系的K波段光度下限时，我们进一步报告说，在本地卷中还存在另一个环状结构，它现在包含了银河系和M31。不过，这个新发现的结构主要是由低质量（卫星）星系组成的。虽然我们在这里只是简单地介绍了这种新方法以及它在观测数据中的首次应用，但利用宇宙结构形成的数值模拟进行的后续工作将揭示星系分布中这种规则模式的起源。此外，这种方法同样适用于在各种天体物理数据中识别类似（甚至不同）的结构（例如在星系红移测量中定位实际的 "重子声振荡球"）。
{"title":"HINORA, a method for detecting ring-like structures in 3D point distributions I: application to the Local Volume Galaxy catalogue","authors":"Edward Olex, Alexander Knebe, Noam I. Libeskind, Dmitry I. Makarov, Stefan Gottlöber","doi":"10.1017/pasa.2024.21","DOIUrl":"https://doi.org/10.1017/pasa.2024.21","url":null,"abstract":"We present a new method – called HINORA (HIgh-NOise RANdom SAmple Consensus) – for the identification of regular structures in 3D point distributions. Motivated by the possible existence of the so-called Council of Giants, i.e. a ring of twelve massive galaxies surrounding the Local Group in the Local Sheet with a radius of 3.75 Mpc, we apply HINORA to the Local Volume Galaxy catalogue confirming its existence. When varying the lower limit of K-band luminosity of the galaxy entering the catalogue, we further report on the existence of another ring-like structure in the Local Volume that now contains the MilkyWay and M31. However, this newly found structure is dominated by low-mass (satellite) galaxies. While we here simply present the novel method as well as its first application to observational data, follow-up work using numerical simulations of cosmic structure formation shall shed light into the origin of such regular patterns in the galaxy distribution. Further, the method is equally suited to identify similar (or even different) structures in various kinds of astrophysical data (e.g. locating the actual ‘baryonic-acoustic oscillation spheres’ in galaxy redshift surveys).","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"41 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140166030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate the relationship between a dark matter halo’s mass profile and measures of the velocity dispersion of kinematic tracers within its gravitational potential. By predicting the scaling relation of the halo mass with the aperture velocity dispersion, Mvir – σap, we present the expected form and dependence of this halo mass tracer on physical parameters within our analytic halo model: parameterized by the halo’s negative inner logarithmic density slope, α, its concentration parameter, c, and its velocity anisotropy parameter, β. For these idealised halos, we obtain a general solution to the Jeans equation, which is projected over the line of sight and averaged within an aperture to form the corresponding aperture velocity dispersion profile. Through dimensional analysis, the Mvir – σap scaling relation is devised explicitly in terms of analytical bounds for these aperture velocity dispersion profiles: allowing constraints to be placed on this relation for motivated parameter choices. We predict the M200 – σap and M500 – σap scaling relations, each with an uncertainty of 60.5% and 56.2%, respectively. These halo mass estimates are found to be weakly sensitive to the halo’s concentration and mass scale, and most sensitive to the size of the aperture radius in which the aperture velocity dispersion is measured, the maximum value for the halo’s inner slope, and the minimum and maximum values of the velocity anisotropy. Our results show that a halo’s structural and kinematic profiles impose only a minor uncertainty in estimating its mass. Consequently, spectroscopic surveys aimed at constraining the halo mass using kinematic tracers can focus on characterising other, more complex sources of uncertainty and observational systematics.
{"title":"Predicting the Scaling Relations between the Dark Matter Halo Mass and Observables from Generalised Profiles I: Kinematic Tracers","authors":"A. Sullivan, C. Power, C. Bottrell","doi":"10.1017/pasa.2024.18","DOIUrl":"https://doi.org/10.1017/pasa.2024.18","url":null,"abstract":"We investigate the relationship between a dark matter halo’s mass profile and measures of the velocity dispersion of kinematic tracers within its gravitational potential. By predicting the scaling relation of the halo mass with the aperture velocity dispersion, <jats:italic>M</jats:italic><jats:sub>vir</jats:sub> – σ<jats:sub>ap</jats:sub>, we present the expected form and dependence of this halo mass tracer on physical parameters within our analytic halo model: parameterized by the halo’s negative inner logarithmic density slope, α, its concentration parameter, <jats:italic>c</jats:italic>, and its velocity anisotropy parameter, β. For these idealised halos, we obtain a general solution to the Jeans equation, which is projected over the line of sight and averaged within an aperture to form the corresponding aperture velocity dispersion profile. Through dimensional analysis, the <jats:italic>M</jats:italic><jats:sub>vir</jats:sub> – σap scaling relation is devised explicitly in terms of analytical bounds for these aperture velocity dispersion profiles: allowing constraints to be placed on this relation for motivated parameter choices. We predict the <jats:italic>M</jats:italic><jats:sub>200</jats:sub> – σ<jats:sub>ap</jats:sub> and <jats:italic>M</jats:italic><jats:sub>500</jats:sub> – σ<jats:sub>ap</jats:sub> scaling relations, each with an uncertainty of 60.5% and 56.2%, respectively. These halo mass estimates are found to be weakly sensitive to the halo’s concentration and mass scale, and most sensitive to the size of the aperture radius in which the aperture velocity dispersion is measured, the maximum value for the halo’s inner slope, and the minimum and maximum values of the velocity anisotropy. Our results show that a halo’s structural and kinematic profiles impose only a minor uncertainty in estimating its mass. Consequently, spectroscopic surveys aimed at constraining the halo mass using kinematic tracers can focus on characterising other, more complex sources of uncertainty and observational systematics.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"153 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140169600","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}
Meghna Menon, Devika Kamath, Maksym Mohorian, Hans Van Winckel, Paolo Ventura
Post-asymptotic giant branch stars (post-AGB) in binary systems, with typical orbital periods between ∼100 to ∼1000 days, result from a poorly understood interaction that terminates their precursory AGB phase. The majority of these binaries display a photospheric anomaly called ‘chemical depletion’, thought to arise froman interaction between the circumbinary disc and the post-AGB star, leading to the reaccretion of pure gas onto the star, devoid of refractory elements due to dust formation. In this paper, we focus on a subset of chemically peculiar binary post-AGBs in the Galaxy and the Magellanic Clouds (MCs). Our detailed stellar parameter and chemical abundance analysis utilising high-resolution optical spectra from VLT+UVES revealed that our targets span a Teff of 4900 - 7250K and [Fe/H] of -0.5 - -1.57 dex. Interestingly, these targets exhibit a carbon ([C/Fe] ranging from 0.5 - 1.0 dex, dependant on metallicity) and s-process enrichment ([s/Fe]≥1dex) contrary to the commonly observed chemical depletion pattern. Using spectral energy distribution (SED) fitting and period-luminosity-colour (PLC) relation methods, we determine the luminosity of the targets (2700 – 8300 L⊙), which enables confirmation of their evolutionary phase and estimation of initial masses (as a function of metallicity) (1 - 2.5M⊙). In conjunction with predictions from dedicated ATON stellar evolutionary models, our results indicate a predominant intrinsic enrichment of carbon and s-process elements in our binary post-AGB targets. We qualitatively rule out extrinsic enrichment and inherited s-process enrichment from the host galaxy as plausible explanations for the observed overabundances. Our chemically peculiar subset of intrinsic carbon and s-process enriched binary post-AGBs also hints at potential variation in the efficiency of chemical depletion between stars with C-rich and O-rich circumbinary disc chemistries. However, critical observational studies of circumbinary disc chemistry, along with specific condensation temperature estimates in C-rich environments, are necessary to address gaps in our current understanding of disc-binary interactions inducing chemical depletion in binary post-AGB systems.
{"title":"s-process Enriched Evolved Binaries in the Galaxy and the Magellanic Clouds","authors":"Meghna Menon, Devika Kamath, Maksym Mohorian, Hans Van Winckel, Paolo Ventura","doi":"10.1017/pasa.2024.19","DOIUrl":"https://doi.org/10.1017/pasa.2024.19","url":null,"abstract":"Post-asymptotic giant branch stars (post-AGB) in binary systems, with typical orbital periods between ∼100 to ∼1000 days, result from a poorly understood interaction that terminates their precursory AGB phase. The majority of these binaries display a photospheric anomaly called ‘chemical depletion’, thought to arise froman interaction between the circumbinary disc and the post-AGB star, leading to the reaccretion of pure gas onto the star, devoid of refractory elements due to dust formation. In this paper, we focus on a subset of chemically peculiar binary post-AGBs in the Galaxy and the Magellanic Clouds (MCs). Our detailed stellar parameter and chemical abundance analysis utilising high-resolution optical spectra from VLT+UVES revealed that our targets span a <jats:italic>T</jats:italic><jats:sub>eff</jats:sub> of 4900 - 7250K and [Fe/H] of -0.5 - -1.57 dex. Interestingly, these targets exhibit a carbon ([C/Fe] ranging from 0.5 - 1.0 dex, dependant on metallicity) and <jats:italic>s</jats:italic>-process enrichment ([s/Fe]≥1dex) contrary to the commonly observed chemical depletion pattern. Using spectral energy distribution (SED) fitting and period-luminosity-colour (PLC) relation methods, we determine the luminosity of the targets (2700 – 8300 L<jats:sub>⊙</jats:sub>), which enables confirmation of their evolutionary phase and estimation of initial masses (as a function of metallicity) (1 - 2.5M<jats:sub>⊙</jats:sub>). In conjunction with predictions from dedicated ATON stellar evolutionary models, our results indicate a predominant intrinsic enrichment of carbon and <jats:italic>s</jats:italic>-process elements in our binary post-AGB targets. We qualitatively rule out extrinsic enrichment and inherited <jats:italic>s</jats:italic>-process enrichment from the host galaxy as plausible explanations for the observed overabundances. Our chemically peculiar subset of intrinsic carbon and <jats:italic>s</jats:italic>-process enriched binary post-AGBs also hints at potential variation in the efficiency of chemical depletion between stars with C-rich and O-rich circumbinary disc chemistries. However, critical observational studies of circumbinary disc chemistry, along with specific condensation temperature estimates in C-rich environments, are necessary to address gaps in our current understanding of disc-binary interactions inducing chemical depletion in binary post-AGB systems.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"25 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140166025","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}
Seyyed Soheil Esmaeili, Abbas Ghasemizad, Omid Naserghodsi
One of the best methods to investigate and calculate a desired quantity using available limited data is the Bayesian statistical method, which has been recently entered the field of nuclear astrophysics and can be used to evaluate the astrophysical S-factors, the cross sections and, as a result, the nuclear reaction rates of Big Bang Nucleosynthesis. This study tries to calculate the astrophysical S-factor and the rate of reaction T(d,n)4He as an important astrophysical reaction with the help of this method in energies lower that electron repulsive barrier, and for this purpose, it uses the R-Software, which leads to improved results in comparison with the non-Bayesian methods for the mentioned reaction rate.
贝叶斯统计方法是利用现有有限数据研究和计算所需数量的最佳方法之一，该方法最近已进入核天体物理学领域，可用于评估大爆炸核合成的天体物理 S 因子、截面以及核反应速率。本研究试图利用这种方法计算天体物理 S 因子和 T(d,n)4He（一种重要的天体物理反应）在低于电子斥力势垒的能量下的反应速率，为此，它使用了 R 软件，与非贝叶斯方法相比，该软件改进了上述反应速率的计算结果。
{"title":"Calculation of Astrophysical Reaction Rate and Uncertainty for T(d,n)4He using Bayesian Statistical Approach","authors":"Seyyed Soheil Esmaeili, Abbas Ghasemizad, Omid Naserghodsi","doi":"10.1017/pasa.2024.15","DOIUrl":"https://doi.org/10.1017/pasa.2024.15","url":null,"abstract":"One of the best methods to investigate and calculate a desired quantity using available limited data is the Bayesian statistical method, which has been recently entered the field of nuclear astrophysics and can be used to evaluate the astrophysical S-factors, the cross sections and, as a result, the nuclear reaction rates of Big Bang Nucleosynthesis. This study tries to calculate the astrophysical S-factor and the rate of reaction T(d,n)<jats:sup>4</jats:sup>He as an important astrophysical reaction with the help of this method in energies lower that electron repulsive barrier, and for this purpose, it uses the R-Software, which leads to improved results in comparison with the non-Bayesian methods for the mentioned reaction rate.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"76 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. S. Shabala, P. M. Yates-Jones, L. A. Jerrim, R. J. Turner, M. G. H. Krause, R. P. Norris, B. S. Koribalski, M. Filipović, L. Rudnick, C. Power, R. M. Crocker
Odd Radio Circles (ORCs) are a class of low surface brightness, circular objects approximately one arcminute in diameter. ORCs were recently discovered in the Australian Square Kilometre Array Pathfinder (ASKAP) data, and subsequently confirmed with follow-up observations on other instruments, yet their origins remain uncertain. In this paper, we suggest that ORCs could be remnant lobes of powerful radio galaxies, re-energised by the passage of a shock. Using relativistic hydrodynamic simulations with synchrotron emission calculated in post-processing, we show that buoyant evolution of remnant radio lobes is alone too slow to produce the observed ORC morphology. However, the passage of a shock can produce both filled and edge-brightnened ORC-like morphologies for a wide variety of shock and observing orientations. Circular ORCs are predicted to have host galaxies near the geometric centre of the radio emission, consistent with observations of these objects. Significantly offset hosts are possible for elliptical ORCs, potentially causing challenges for accurate host galaxy identification. Observed ORC number counts are broadly consistent with a paradigm in which moderately powerful radio galaxies are their progenitors.
{"title":"Are Odd Radio Circles phoenixes of powerful radio galaxies?","authors":"S. S. Shabala, P. M. Yates-Jones, L. A. Jerrim, R. J. Turner, M. G. H. Krause, R. P. Norris, B. S. Koribalski, M. Filipović, L. Rudnick, C. Power, R. M. Crocker","doi":"10.1017/pasa.2024.11","DOIUrl":"https://doi.org/10.1017/pasa.2024.11","url":null,"abstract":"Odd Radio Circles (ORCs) are a class of low surface brightness, circular objects approximately one arcminute in diameter. ORCs were recently discovered in the Australian Square Kilometre Array Pathfinder (ASKAP) data, and subsequently confirmed with follow-up observations on other instruments, yet their origins remain uncertain. In this paper, we suggest that ORCs could be remnant lobes of powerful radio galaxies, re-energised by the passage of a shock. Using relativistic hydrodynamic simulations with synchrotron emission calculated in post-processing, we show that buoyant evolution of remnant radio lobes is alone too slow to produce the observed ORC morphology. However, the passage of a shock can produce both filled and edge-brightnened ORC-like morphologies for a wide variety of shock and observing orientations. Circular ORCs are predicted to have host galaxies near the geometric centre of the radio emission, consistent with observations of these objects. Significantly offset hosts are possible for elliptical ORCs, potentially causing challenges for accurate host galaxy identification. Observed ORC number counts are broadly consistent with a paradigm in which moderately powerful radio galaxies are their progenitors.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"33 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140045394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：