Publications of the Astronomical Society of Australia最新文献

{"title":"An Optical Daytime Astronomy Pathfinder for the Huntsman Telescope","authors":"Sarah E. Caddy, Lee R. Spitler, Simon C. Ellis","doi":"10.1017/pasa.2024.43","DOIUrl":"https://doi.org/10.1017/pasa.2024.43","url":null,"abstract":"\u0000 Observing stars and satellites in optical wavelengths during the day (optical daytime astronomy) has begun a resurgence of interest. The recent dramatic dimming event of Betelgeuse has spurred interest in continuous monitoring of the brightest variable stars, even when an object is only visible during the day due to their proximity to the Sun. In addition, an exponential increase in the number of satellites being launched into low Earth orbit in recent years has driven an interest in optical daytime astronomy for the detection and monitoring of satellites in space situational awareness (SSA) networks. In this paper we explore the use of the Huntsman Telescope as an optical daytime astronomy facility, by conducting an exploratory survey using a pathfinder instrument. We find that an absolute photometric accuracy between 1 - 10% can be achieved during the day, with a detection limit of V band 4.6 mag at midday in sloan g‚ and r‚ wavelengths. In addition we characterise the daytime sky brightness, colour and observing conditions in order to achieve the most reliable and highest signal-to-noise observations within the limitations of the bright sky background. We undertake a 7 month survey of the brightness of Betelgeuse during the day and demonstrate that our results are in agreement with measurements from other observatories. Finally we present our preliminary results that demonstrate obtaining absolute photometric measurements of the International Space Station during the day.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141120103","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":"Rotation of the Globular Cluster Population of the Dark Matter Deficient Galaxy NGC 1052-DF4: Implication for the total mass","authors":"Yuan Li, B. Brewer, G. F. Lewis","doi":"10.1017/pasa.2024.42","DOIUrl":"https://doi.org/10.1017/pasa.2024.42","url":null,"abstract":"\u0000 We explore the globular cluster population of NGC 1052-DF4, a dark matter deficient galaxy, using Bayesian inference to search for the presence of rotation. The existence of such a rotating component is relevant to the estimation of the mass of the galaxy, and therefore the question of whether NGC 1052-DF4 is truly deficient of dark matter,similar to NGC 1052-DF2, another galaxy in the same group. The rotational characteristics of seven globular clusters in NGC 1052-DF4 were investigated, finding that a non-rotating kinematic model has a higher Bayesian evidence than a rotating model, by a factor of approximately 2.5. In addition, we find that under the assumption of rotation, its amplitude must be small. This distinct lack of rotation strengthens the case that, based on its intrinsic velocity dispersion, NGC 1052-DF4 is a truly dark matter deficient galaxy.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141127561","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":"Mode identification and period fitting in six pulsating hot subdwarfs","authors":"S. K. Sahoo, A. S. Baran, P. Németh, H. Worters, S. Pramod Kumar, S. Joshi, D. Kilkenny","doi":"10.1017/pasa.2024.38","DOIUrl":"https://doi.org/10.1017/pasa.2024.38","url":null,"abstract":"\u0000 We report the results of our analysis of six gravity-mode pulsating hot subdwarf stars observed in the short cadence mode by Transiting Exoplanet Survey Satellite. We detected at least 10 pulsation periods in each star, searched for multiplets, and used an asymptotic period spacing to identify modes.We used a grid of evolutionary and pulsation models calculated with the MESA and GYRE, along with spectroscopic parameters and modal degree identification, to derive the physical properties of the stars.We checked the relation between the helium content and pulsations and found that no pulsator exists among the extremely helium-rich hot subdwarfs, while the number of detected pulsators in other helium groups increases as the helium content decreases.We found p- and g-mode hot subdwarfs pulsators in all Galactic populations.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140970732","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":"On bursty star formation during cosmological reionization - how does it influence the baryon mass content of dark matter halos?","authors":"Anand Menon, Chris Power","doi":"10.1017/pasa.2024.39","DOIUrl":"https://doi.org/10.1017/pasa.2024.39","url":null,"abstract":"The baryon mass content (i.e. stellar and gas mass) of dark matter halos in the early Universe depends on both global factors - e.g. ionizing ultraviolet (UV) radiation background - and local factors - e.g. star formation efficiency and assembly history. We use a lightweight semi-analytical model to investigate how both local and global factors impact the halo baryon mass content at redshifts of <jats:italic>z</jats:italic> ≥ 5. Our model incorporates a time delay between when stars form and when they produce feedback of 0 ≤ <jats:italic>t<jats:sup>d</jats:sup></jats:italic>/Myr ≤ 30, which can drive bursts of star formation, and a mass and redshift dependent UV background, which captures the influence of cosmological reionization on gas accretion onto halos. We use statistically representative halo assembly histories and assume that the cosmological gas accretion rate is proportional to the halo mass accretion rate. Delayed (<jats:italic>t<jats:sup>d</jats:sup></jats:italic>&gt;0) feedback leads to oscillations in gas mass with cosmic time, behaviour that cannot be captured with instantaneous feedback (<jats:italic>t<jats:sup>d</jats:sup></jats:italic>=0). Highly efficient star formation drives stronger oscillations, while strong feedback impacts when oscillations occur; in contrast, inefficient star formation and weak feedback produce similar long-term behaviour to that observed in instantaneous feedback models. If the delayed feedback timescale is too long, a halo retains its gas reservoir but the feedback suppresses star formation. Our model predicts that lower mass systems (halo masses <jats:italic>m</jats:italic><jats:sub>h</jats:sub> ≤ 10<jats:sup>7</jats:sup>M<jats:sub>⊙</jats:sub>) at <jats:italic>z</jats:italic> ≤ 10 should be strongly gas deficient (<jats:italic>m</jats:italic>g → 0), whereas higher mass systems retain their gas reservoirs because they are sufficiently massive to continue accreting gas through cosmological reionization. Interestingly, in higher mass halos, the median <jats:italic>m</jats:italic><jats:sub>⋆</jats:sub>/(<jats:italic>m</jats:italic><jats:sub>⋆</jats:sub> + <jats:italic>m</jats:italic><jats:sub>g</jats:sub>) ≃ 0.01 – 0.05, but is a factor of 3-5 smaller when feedback is delayed. Our model does not include seed supermassive black hole feedback, which is necessary to explain massive quenched galaxies in the early Universe.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140940649","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":"MOSEL survey: Unwrapping the Epoch of Reionization through mimic galaxies at Cosmic Noon","authors":"Ravi Jaiswar, Anshu Gupta, Elisabete da Cunha, Cathryn M. Trott, Anishya Harshan, Andrew Battisti, Ben Forrest","doi":"10.1017/pasa.2024.37","DOIUrl":"https://doi.org/10.1017/pasa.2024.37","url":null,"abstract":"The nature of the first galaxies that reionized the universe during the Epoch of Reionization (EoR) remains unclear. Attempts to directly determine spectral properties of these early galaxies are affected by both limited photometric constraints across the spectrum and by the opacity of the intergalactic medium (IGM) to the Lyman Continuum (LyC) at high redshift. We approach this by analysing properties of analogous extreme emission line galaxies (EELGs, [OIII]+Hbeta EW&gt; 400) at 2.5 &lt; <jats:italic>z</jats:italic> &lt; 4 from the ZFOURGE survey using the Multi-wavelength Analysis of Galaxy Physical Properties (MAGPHYS) SED fitting code. We compare these to galaxies at <jats:italic>z</jats:italic> &gt; 5.5 observed with the James Webb Space Telesope (JWST) with self-consistent spectral energy distribution fitting methodology. This work focuses on the comparison of their UV slopes (β<jats:italic>P</jats:italic>), ionizing photon production efficiencies ξ<jats:italic>ion</jats:italic>, star formation rates and dust properties to determine the effectiveness of this analogue selection technique. We report the median ionizing photon production efficiencies as <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S1323358024000377_inline1.png\"/> for our ZFOURGE control, ZFOURGE EELG, JADES and CEERS samples respectively. ZFOURGE EELGs are 0.57 dex lower in stellar mass and have half the dust extinction, compared to their ZFOURGE control counterparts. They also have a similar specific star formation rates and β<jats:italic>P</jats:italic> to the <jats:italic>z</jats:italic> &gt; 5.5 samples. We find that EELGs at low redshift (2.5 &lt; <jats:italic>z</jats:italic> &lt; 4) are analogous to EoR galaxies in their dust attenuation and specific star formation rates. Their extensive photometric coverage and the accessibility of their LyC region opens pathways to infer stellar population properties in the EoR.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140940871","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":"Reduced-resolution beamforming: lowering the computational cost for pulsar and technosignature surveys","authors":"D. C. Price","doi":"10.1017/pasa.2024.35","DOIUrl":"https://doi.org/10.1017/pasa.2024.35","url":null,"abstract":"In radio astronomy, the science output of a telescope is often limited by computational resources. This is especially true for transient and technosignature surveys that need to search high-resolution data across a large parameter space. The tremendous data volumes produced by modern radio array telescopes exacerbate these processing challenges. Here, we introduce a ‘reduced-resolution’ beamforming approach to alleviate downstream processing requirements. Our approach, based on post-correlation beamforming, allows sensitivity to be traded against the number of beams needed to cover a given survey area. Using the MeerKAT and Murchison Widefield Array telescopes as examples, we show that survey speed can be vastly increased, and downstream signal processing requirements vastly decreased, if a moderate sacrifice to sensitivity is allowed. We show the reduced-resolution beamforming technique is intimately related to standard techniques used in synthesis imaging. We suggest that reduced-resolution beamforming should be considered to ease data processing challenges in current and planned searches; further, reduced-resolution beamforming may provide a path to computationally-expensive search strategies previously considered infeasible.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140940849","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":"System design and validation of Central Redundant Array Mega-tile (CRAM)","authors":"Aishwarya Selvaraj, Randall B Wayth, Cathryn M Trott, Gurashish Singh Bhatia","doi":"10.1017/pasa.2024.33","DOIUrl":"https://doi.org/10.1017/pasa.2024.33","url":null,"abstract":"Exploration of the 21cm signal during the Cosmic Dawn and the Epoch of Reionisation (EoR) can unravel the mysteries of the early Universe when the first stars and galaxies were born and ionised, respectively. However, the 21cm signal is exceptionally weak, and thus, the detection amidst the bright foregrounds is extremely challenging. The MurchisonWidefield Array (MWA) aims to measure the brightness temperature fluctuations of neutral hydrogen from the early Universe. The MWA telescope observes the radio sky with a large Field of View (FoV) that causes the bright galaxies, especially near the horizon, to contaminate the measurements. These foregrounds contaminating the EoR datasets must be meticulously removed or treated to detect the signal successfully. The Central Redundant Array Mega-tile (CRAM) is a zenith-pointing new instrument, installed at the centre of the MWA Phase II southern hexagonal configuration, comprising of 64 dipoles in an 8 × 8 configuration with a FoV half the width of the MWA’s at every frequency under consideration. The primary objective of this new instrument is to mitigate the impact of bright radio sources near the field centre in accordance with the reduced primary beamshape and to reduce the contamination of foreground sources near the horizon with the reduced sidelobe response of the larger array configuration. In this paper, we introduce the new instrument to the community and present the system architecture and characteristics of the instrument. Using the first light observations, we determine the CRAM system temperature and system performance.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140628654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Verifying the Australian MWA EoR pipeline I: 21-cm sky model and correlated measurement density","authors":"J. L. B. Line, C. M. Trott, J. H. Cook, B. Greig, N. Barry, C. H. Jordan","doi":"10.1017/pasa.2024.31","DOIUrl":"https://doi.org/10.1017/pasa.2024.31","url":null,"abstract":"We present the first of two papers dedicated to verifying the Australian Epoch of Reionisation pipeline (<jats:monospace>AusEoRPipe</jats:monospace>) through simulation. The <jats:monospace>AusEoRPipe</jats:monospace> aims to disentangle 21-cm radiation emitted by gas surrounding the very first stars from contaminating foreground astrophysical sources, and has been in development for close to a decade. In this paper, we build an accurate 21-cm sky model that can be used by the <jats:monospace>WODEN</jats:monospace> simulation software to create visibilities containing a predictable 21-cm signal. We verify that the power spectrum estimator <jats:monospace>CHIPS</jats:monospace> can recover this signal in the absence of foregrounds. We also investigate how measurements in Fourier-space are correlated, and how their gridded density affects the power spectrum. We measure and fit for this effect using Gaussian-noise simulations of the MWA phase I layout. We find a gridding density correction factor of 2.651 appropriate for integrations equal to or greater than 30 minutes of data, which contain observations with multiple primary beam pointings and LSTs. Paper II of this series will use the results of this paper to test the <jats:monospace>AusEoRPipe</jats:monospace> in the presence of foregrounds and instrumental effects.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140627895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Galaxy 3D Shape Recovery using Mixture Density Network","authors":"Suk Yee Yong, K. E. Harborne, Caroline Foster, Robert Bassett, Gregory B. Poole, Mitchell Cavanagh","doi":"10.1017/pasa.2024.32","DOIUrl":"https://doi.org/10.1017/pasa.2024.32","url":null,"abstract":"Since the turn of the century, astronomers have been exploiting the rich information afforded by combining stellar kinematic maps and imaging in an attempt to recover the intrinsic, three-dimensional (3D) shape of a galaxy. A common intrinsic shape recovery method relies on an expected monotonic relationship between the intrinsic misalignment of the kinematic and morphological axes and the triaxiality parameter. Recent studies have, however, cast doubt about underlying assumptions relating shape and intrinsic kinematic misalignment. In this work, we aim to recover the 3D shape of <jats:italic>individual</jats:italic> galaxies using their projected stellar kinematic and flux distributions using a supervised machine learning approach with mixture density network (MDN). Using a mock dataset of the EAGLE hydrodynamical cosmological simulation, we train the MDN model for a carefully selected set of common kinematic and photometric parameters. Compared to previous methods, we demonstrate potential improvements achieved with the MDN model to retrieve the 3D galaxy shape along with the uncertainties, especially for prolate and triaxial systems. We make specific recommendations for recovering galaxy intrinsic shapes relevant for current and future integral field spectroscopic galaxy surveys.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140627892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-frequency pulse-jitter measurement with the uGMRT I : PSR J0437–4715","authors":"Tomonosuke Kikunaga, Shinnosuke Hisano, Neelam Dhanda Batra, Shantanu Desai, Bhal Chandra Joshi, Manjari Bagchi, T. Prabu, Keitaro Takahashi, Swetha Arumugam, Adarsh Bathula, Subhajit Dandapat, Debabrata Deb, Churchil Dwivedi, Yashwant Gupta, Shebin Jose Jacob, Fazal Kareem, K Nobleson, Pragna Mamidipaka, Avinash Kumar Paladi, Arul Pandian B, Prerna Rana, Jaikhomba Singha, Aman Srivastava, Mayuresh Surnis, Pratik Tarafdar","doi":"10.1017/pasa.2024.30","DOIUrl":"https://doi.org/10.1017/pasa.2024.30","url":null,"abstract":"High-precision pulsar timing observations are limited in their accuracy by the jitter noise that appears in the arrival time of pulses. Therefore, it is important to systematically characterise the amplitude of the jitter noise and its variation with frequency. In this paper, we provide jitter measurements from low-frequency wideband observations of PSR J0437–4715 using data obtained as part of the Indian Pulsar Timing Array experiment. We were able to detect jitter in both the 300 - 500 MHz and 1260 - 1460 MHz observations of the upgraded Giant Metrewave Radio Telescope (uGMRT). The former is the first jitter measurement for this pulsar below 700 MHz, and the latter is in good agreement with results from previous studies. In addition, at 300 - 500 MHz, we investigated the frequency dependence of the jitter by calculating the jitter for each sub-banded arrival time of pulses. We found that the jitter amplitude increases with frequency. This trend is opposite as compared to previous studies, indicating that there is a turnover at intermediate frequencies. It will be possible to investigate this in more detail with uGMRT observations at 550 - 750 MHz and future high sensitive wideband observations from next generation telescopes, such as the Square Kilometre Array. We also explored the effect of jitter on the high precision dispersion measure (DM) measurements derived from short duration observations. We find that even though the DM precision will be better at lower frequencies due to the smaller amplitude of jitter noise, it will limit the DM precision for high signal-to-noise observations, which are of short durations. This limitation can be overcome by integrating for a long enough duration optimised for a given pulsar.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140613000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}