Publications of the Astronomical Society of Australia最新文献

{"title":"Early Accretion Onset in Long-Period Isolated Pulsars","authors":"M.D. Afonina, A.V. Biryukov, S.B. Popov","doi":"10.1017/pasa.2024.12","DOIUrl":"https://doi.org/10.1017/pasa.2024.12","url":null,"abstract":"We model long-term magneto-rotational evolution of isolated neutron stars with long initial spin periods. This analysis is motivated by the recent discovery of young long-period neutron stars observed as periodic radio sources: PSR J0901-4046, GLEAM-X J1627-52, and GPM J1839-10. Our calculations demonstrate that for realistically rapid spin-down during the propeller stage isolated neutron stars with velocities ≲ 100 km s–1 and assumed long initial spin periods can reach the stage of accretion from the interstellar medium within at most a few billion years as they are born already at the propeller stage or sufficiently close to the critical period of the ejector-propeller transition. If neutron stars with long initial spin periods form a relatively large fraction of all Galactic neutron stars then the number of isolated accretors is substantially larger than it has been predicted by previous studies.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"19 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140007414","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":"DARK SAGE: Next-generation semi-analytic galaxy evolution with multidimensional structure and minimal free parameters","authors":"Adam R. H. Stevens, Manodeep Sinha, Alexander Rohl, Mawson W. Sammons, Boryana Hadzhiyska, César Hernández-Aguayo, Lars Hernquist","doi":"10.1017/pasa.2024.14","DOIUrl":"https://doi.org/10.1017/pasa.2024.14","url":null,"abstract":"After more than five years of development, we present a new version of Dark Sage, a semi-analytic model (SAM) of galaxy formation that breaks the mould for models of its kind. Included among the major changes is an overhauled treatment of stellar feedback that is derived from energy conservation, operates on local scales, affects gas gradually over time rather than instantaneously, and predicts a mass-loading factor for every galaxy. Building on the model’s resolved angularmomentum structure of galaxies, we now consider the heating of stellar discs, delivering predictions for disc structure both radially and vertically. We add a further dimension to stellar discs by tracking the distribution of stellar ages in each annulus. Each annulus–age bin has its own velocity dispersion and metallicity evolved in the model. This allows Dark Sage to make structural predictions for galaxies that previously only hydrodynamic simulations could. We present the model as run on the merger trees of the highest-resolution gravity-only simulation of the MillenniumTNG suite. Despite its additional complexity relative to other SAMs, Dark Sage only has three free parameters, the least of any SAM, which we calibrate exclusively against the cosmic star formation history and the <jats:italic>z</jats:italic>=0 stellar and Hi mass functions using a particle-swarm optimisation method. The Dark Sage codebase, written in C and python, is publicly available at <jats:uri xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"https://github.com/arhstevens/DarkSage\">https://github.com/arhstevens/DarkSage</jats:uri>.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"233 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140007413","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":"EMU/GAMA: A Technique for Detecting Active Galactic Nuclei in Low Mass Systems","authors":"Jahang Prathap, Andrew M. Hopkins, Aaron S. G. Robotham, Sabine Bellstedt, José Afonso, Ummee T. Ahmed, Maciej Bilicki, Malcolm N. Bremer, Sarah Brough, Michael J. I. Brown, Yjan Gordon, Benne W. Holwerda, Denis Leahy, Ángel R. López-Sánchez, Joshua R. Marvil, Tamal Mukherjee, Isabella Prandoni, Stanislav S. Shabala, Tessa Vernstrom, Tayyaba Zafar","doi":"10.1017/pasa.2024.9","DOIUrl":"https://doi.org/10.1017/pasa.2024.9","url":null,"abstract":"We propose a new method for identifying active galactic nuclei (AGN) in low mass (M<jats:sub>*</jats:sub> ≤ 10<jats:sup>10</jats:sup>M<jats:sub>⊙</jats:sub>) galaxies. This method relies on spectral energy distribution (SED) fitting to identify galaxies whose radio flux density has an excess over that expected from star formation alone. Combining data in the Galaxy and Mass Assembly (GAMA) G23 region from GAMA, Evolutionary Map of the Universe (EMU) early science observations, andWide-field Infrared Survey Explorer (WISE), we compare this technique with a selection of different AGN diagnostics to explore the similarities and differences in AGN classification. We find that diagnostics based on optical and near-infrared criteria (the standard BPT diagram, the WISE colour criterion, and the mass-excitation, or MEx diagram) tend to favour detection of AGN in high mass, high luminosity systems, while the “P<jats:sc>ro</jats:sc>S<jats:sc>pect</jats:sc>” SED fitting tool can identify AGN efficiently in low mass systems. We investigate an explanation for this result in the context of proportionally lower mass black holes in lower mass galaxies compared to higher mass galaxies and differing proportions of emission from AGN and star formation dominating the light at optical and infrared wavelengths as a function of galaxy stellar mass. We conclude that SED-derived AGN classification is an efficient approach to identify low mass hosts with low radio luminosity AGN.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"175 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139925851","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":"Plane Polarization in Comptonization process : a Monte Carlo study","authors":"Nagendra Kumar","doi":"10.1017/pasa.2024.8","DOIUrl":"https://doi.org/10.1017/pasa.2024.8","url":null,"abstract":"High energies emissions observed in X-ray binaries (XRBs), active galactic nuclei (AGNs) are linearly polarized. The prominent mechanism for X-ray is the Comptonization process. We revisit the theory for polarization in Compton scattering with unpolarized electrons, and note that the (k×k′)-coordinate (in which, (k×k<jats:sup>′<jats:sup>) acts as a z-axis, here k and k<jats:sup>′</jats:sup> are incident and scattered photon momentum respectively) is more convenient to describe it. Interestingly, for a fixed scattering plane the degree of polarization PD after single scattering for random oriented low-energy unpolarized incident photons is ~0.3. At the scattering angle θ = 0 orθ≡ [0,25◦], the modulation curve of k</jats:sup>′</jats:sup> exhibits the same PD and PA (angle of polarization) of k, and even the distribution of projection of electric vector of k<jats:sup>′</jats:sup> (k<jats:sup>′</jats:sup>e) on perpendicular plane to the k indicates same (so, an essential criteria for detector designing). We compute the polarization state in Comptonization process using Monte Carlo methods with considering a simple spherical corona. We obtain the PD of emergent photons as a function of =-angle (or alternatively, the disk inclination angle i) on a meridian plane (i.e., the laws of darkening, formulated by Chandrasekhar, 1946) after single scattering with unpolarized incident photons. To explore the energy dependency we consider a general spectral parameter set corresponding to hard and soft states of XRBs, we find that for average scattering no. 〈N<jats:sub>sc</jats:sub>〉 ~1.1 the PD is independent of energy and PA ~ 90◦ (k<jats:sup>′</jats:sup><jats:sub>e</jats:sub> is parallel to the disk plane), and for hNsci ~5 the PD value is maximum for i = 45◦. We also compare the results qualitatively with observation of IXPE for five sources.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"21 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139589090","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 commensal Fast Radio Burst search pipeline for the Murchison Widefield Array","authors":"M. Sokolowski, I. S. Morrison, D. Price, G. Sleap, B. Crosse, A. Williams, L. Williams, C. James, B. W. Meyers, S. McSweeney, N. D. R. Bhat, G. Anderson","doi":"10.1017/pasa.2024.7","DOIUrl":"https://doi.org/10.1017/pasa.2024.7","url":null,"abstract":"We present a demonstration version of a commensal pipeline for Fast Radio Burst (FRB) searches using a real-time incoherent beam from the Murchison Widefield Array (MWA). The main science target of the pipeline are bright nearby FRBs from the local Universe (including Galactic FRBs like from SGR 1935+2154) which are the best candidates to probe FRB progenitors and understand physical mechanisms powering these extremely energetic events. Recent FRB detections by LOFAR (down to 110 MHz), the Green Bank Telescope (at 350 MHz), and CHIME detections extending down to 400 MHz, prove that there is a population of FRBs that can be detected below 350 MHz. The new MWA beamformer, known as the ‘MWAX multibeam beamformer’, can form multiple incoherent and coherent beams (with different parameters) commensally to any on-going MWA observations. One of the beams is currently used for FRB searches (tested in 10 kHz frequency resolution and time resolutions between 0.1 and 100 ms). A second beam (in 1 Hz and 1 s frequency and time resolutions respectively) is used for the Search for Extraterrestrial Intelligence (SETI) project. This paper focuses on the FRB search pipeline and its verification on selected known bright pulsars. The pipeline uses the FREDDA implementation of the Fast Dispersion Measure Transform algorithm (FDMT) for single pulse searches. Initially, it was tested during standard MWA observations, and more recently using dedicated observations of a sample of 11 bright pulsars. The pulsar PSR J0835-4510 (Vela) has been routinely used as the primary probe of the data quality because its folded profile was always detected in the frequency band 200 – 230MHz with typical signal-to-noise ratio <jats:italic>&gt;</jats:italic>10, which agrees with the expectations. Similarly, the low dispersion measure pulsar PSR B0950+08 was always detected in folded profile in the frequency band 140 – 170 MHz, and so far has been the only object for which single pulses were detected. We present the estimated sensitivity of the search in the currently limited observing bandwidth of a single MWA coarse channel (1.28 MHz) and for the upgraded, future system with 12.8MHz (10 channels) of bandwidth. Based on expected sensitivity and existing FRB rate measurements, we project an FRB detection rate between a few and a few tens per year with large uncertainty due to unknown FRB rates at low frequencies.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"10 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139589334","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":"Survey and Monitoring of ASKAP’s RFI Environment and Trends I: Flagging Statistics","authors":"L. Lourenço, A. P. Chippendale, B. Indermuehle, V. A. Moss, Tara Murphy, T. J. Galvin, G. Hellbourg, A. W. Hotan, E. Lenc, M. T. Whiting","doi":"10.1017/pasa.2024.4","DOIUrl":"https://doi.org/10.1017/pasa.2024.4","url":null,"abstract":"We present an initial analysis of Radio Frequency Interference (RFI) flagging statistics from archived Australian SKA Pathfinder (ASKAP) observations for the “Survey and Monitoring of ASKAP’s RFI environment and Trends” (SMART) project. SMART is a two-part observatoryled project combining analysis of archived observations with a dedicated, comprehensive RFI survey. The survey component covers ASKAP’s full 700MHz to 1800MHz frequency range, including bands not typically used due to severe RFI. Observations are underway to capture a detailed snapshot of the ASKAP RFI environment over representative 24 h periods. In addition to this dedicated survey, we routinely archive and analyse flagging statistics for all scientific observations to monitor the observatory’s RFI environment in near real-time. We use the telescope itself as a very sensitive RFI monitor and directly assess the fraction of scientific observations impacted by RFI. To this end, flag tables are now automatically ingested and aggregated as part of routine ASKAP operations for all science observations, as a function of frequency and time. The data presented in this paper come from processing all archived data for several ASKAP Survey Science Projects (SSPs). We found that the average amount of flagging due to RFI across the routinely-used ‘clean’ continuum science bands is 3%. The ‘clean’ mid band from 1293MHz to 1437MHz (excluding the 144MHz below 1293MHz impacted by radionavigation-satellites which is discarded before processing) is the least affected by RFI, followed by the ‘clean’ low band from 742MHz to 1085MHz. ASKAP SSPs lose most of their data to the mobile service in the low band, aeronautical service in the mid band and satellite navigation service in the 1510MHz to 1797MHz high band. We also show that for some of these services, the percentage of discarded data has been increasing year-on-year. SMART provides a unique opportunity to study ASKAP’s changing RFI environment, including understanding and updating the default flagging behaviour, inferring the suitability of and calibrating RFI monitoring equipment, monitoring spectrum management compliance in the Australian Radio Quiet Zone –Western Australia (ARQZWA), and informing the implementation of a suite of RFI mitigation techniques.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"33 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139588799","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":"M2P2 I: Maser Monitoring Parkes Program data description and Stokes-I OH maser variability","authors":"Anita Hafner, James A. Green, Ashie Burdon, Elena Popova, Dmitry Ladeyschikov, Shari Breen, Ross Alexander Burns, James O. Chibueze, M. D. Gray, Busaba Hutawarakorn Kramer, Gordon MacLeod, Andrey Sobolev, Maxim Voronkov","doi":"10.1017/pasa.2024.3","DOIUrl":"https://doi.org/10.1017/pasa.2024.3","url":null,"abstract":"The Maser Monitoring Parkes Project (M2P2) is an ongoing project to observe masers towards high mass star forming regions (HMSFRs) using the 64m CSIRO Parkes radio telescope, Murriyang. In this paper we outline the project and introduce Stokes-I data from the first two years of observations. For the 63 sightlines observed in this project we identify a total of 1514 individual maser features: 14.4% of these (203) towards 27 sightlines show significant variability. Most of these (160/203) are seen in the main-line transitions of OH at 1665 and 1667 MHz, but this data set also includes a significant number of variable features in the satellite lines at 1612 and 1720MHz (33 and 10 respectively), most of which (24 and 9 respectively) appear to be associated with the HMSFRs. We divide these features into 4 broad categories based on the behaviour of their intensity over time: flares (6%), periodic (11%), long-term trends (33%) and ‘other’ (50%). Variable masers provide a unique laboratory for the modelling of local environmental conditions of HMSFRs, and follow-up publications will delve into this in more detail.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"388 2 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139561108","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":"Multi-periodicity in the High Gravity Blue Large Amplitude Pulsator ZTF J071329.02-152125.2","authors":"Chris Koen","doi":"10.1017/pasa.2024.5","DOIUrl":"https://doi.org/10.1017/pasa.2024.5","url":null,"abstract":"New time series photometry of the pulsating hot subdwarf star ZTF J071329.02-152125.2 is presented. Rapid (timescale of hours) changes in the amplitude of the known pulsation in the star was observed. This could be ascribed to beating between three closely spaced frequencies, but analysis of all available photometry finds a range of different frequencies, with widely different amplitudes. A new frequency of 49.66 d<jats:sup>−1</jats:sup>, suggestive of gravity-mode pulsation, was also discovered. The star may be a hybrid p-mode/g-mode hot subdwarf pulsator which sometimes exhibits extraordinarily large amplitude variability.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"252 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139561343","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":"EMU/GAMA: Radio detected galaxies are more obscured than optically selected galaxies","authors":"U. T. Ahmed, A. M. Hopkins, J. Ware, Y. A. Gordon, M. Bilicki, M. J. I. Brown, M. Cluver, G. Gürkan, Á. R. López-Sánchez, D. A. Leahy, L. Marchetti, S. Phillipps, I. Prandoni, N. Seymour, E. N. Taylor, E. Vardoulaki","doi":"10.1017/pasa.2024.2","DOIUrl":"https://doi.org/10.1017/pasa.2024.2","url":null,"abstract":"We demonstrate the importance of radio selection in probing heavily obscured galaxy populations. We combine Evolutionary Map of the Universe (EMU) Early Science data in the Galaxy and Mass Assembly (GAMA) G23 field with the GAMA data, providing optical photometry and spectral line measurements, together withWide-field Infrared Survey Explorer (WISE) infrared (IR) photometry, providing IR luminosities and colours. We investigate the degree of obscuration in star forming galaxies, based on the Balmer decrement (BD), and explore how this trend varies, over a redshift range of 0 &lt; <jats:italic>z</jats:italic> &lt; 0.345. We demonstrate that the radio detected population has on average higher levels of obscuration than the parent optical sample, arising through missing the lowest BD and lowest mass galaxies, which are also the lower star formation rate (SFR) and metallicity systems. We discuss possible explanations for this result, including speculation around whether it might arise from steeper stellar initial mass functions in low mass, low SFR galaxies.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"1 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139495701","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":"4XMM J182531.5–144036: A new persistent Be/X-ray binary found within the XMM-Newton serendipitous survey","authors":"A.B. Mason, A.J Norton, J.S. Clark, S.A Farrell, A.J. Gosling","doi":"10.1017/pasa.2024.6","DOIUrl":"https://doi.org/10.1017/pasa.2024.6","url":null,"abstract":"We aim to investigate the nature of time-variable X-ray sources detected in the <jats:italic>XMM-Newton</jats:italic> serendipitous survey. The X-ray light curves of objects in the <jats:italic>XMM-Newton</jats:italic> serendipitous survey were searched for variability and coincident serendipitous sources observed by <jats:italic>Chandra</jats:italic> were also investigated. Subsequent infrared spectroscopy of the counterparts to the X-ray objects that were identified using UKIDSS was carried out using <jats:italic>ISAAC</jats:italic> on the VLT. We found that the object 4XMM J182531.5–144036 detected in the XMM-Newton serendipitous survey in April 2008 was also detected by Chandra as CXOU J182531.4–144036 in July 2004. Both observations reveal a hard X-ray source displaying a coherent X-ray pulsation at a period of 781 s. The source position is coincident with a <jats:italic>K</jats:italic> = 14 mag infrared object whose spectrum exhibits strong HeI and Brγ emission lines and an infrared excess above that of early B-type dwarf or giant stars.We conclude that 4XMM J182531.5–144036 is a Be/X-ray binary pulsar exhibiting persistent X-ray emission and is likely in a long period, low eccentricity orbit, similar to X Per.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"31 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139476424","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}