S. Weston, A. D. Witt, H. Krásná, K. Bail, Sara Hardin, D. Gordon, F. Shu, A. Fey, M. Schartner, S. Basu, O. Titov, D. Behrend, C. Jacobs, W. Hankey, Federico Salguero, J. Reynolds, Le Bail Krásná H, CS Jacobs
Abstract The International VLBI Service for Geodesy and Astrometry (IVS) regularly provides high-quality data to produce Earth Orientation Parameters (EOP), and for the maintenance and realisation of the International Terrestrial and Celestial Reference Frames, ITRF and ICRF. The first iteration of the celestial reference frame (CRF) at radio wavelengths, the ICRF1, was adopted by the International Astronomical Union (IAU) in 1997 to replace the FK5 optical frame. Soon after, the IVS began official operations and in 2009 there was a significant increase in data sufficient to warrant a second iteration of the CRF, ICRF2. The most recent ICRF3, was adopted by the IAU in 2018. However, due to the geographic distribution of observing stations being concentrated in the Northern hemisphere, CRFs are generally weaker in the South due to there being fewer Southern Hemisphere observations. To increase the Southern Hemisphere observations, and the density, precision of the sources, a series of deep South observing sessions was initiated in 1995. This initiative in 2004 became the IVS Celestial Reference Frame Deep South (IVS-CRDS) observing programme. This paper covers the evolution of the CRDS observing programme for the period 1995–2021, details the data products and results, and concludes with a summary of upcoming improvements to this ongoing project.
{"title":"On more than two decades of Celestial Reference Frame VLBI observations in the deep south: IVS-CRDS (1995–2021)","authors":"S. Weston, A. D. Witt, H. Krásná, K. Bail, Sara Hardin, D. Gordon, F. Shu, A. Fey, M. Schartner, S. Basu, O. Titov, D. Behrend, C. Jacobs, W. Hankey, Federico Salguero, J. Reynolds, Le Bail Krásná H, CS Jacobs","doi":"10.1017/pasa.2023.33","DOIUrl":"https://doi.org/10.1017/pasa.2023.33","url":null,"abstract":"Abstract The International VLBI Service for Geodesy and Astrometry (IVS) regularly provides high-quality data to produce Earth Orientation Parameters (EOP), and for the maintenance and realisation of the International Terrestrial and Celestial Reference Frames, ITRF and ICRF. The first iteration of the celestial reference frame (CRF) at radio wavelengths, the ICRF1, was adopted by the International Astronomical Union (IAU) in 1997 to replace the FK5 optical frame. Soon after, the IVS began official operations and in 2009 there was a significant increase in data sufficient to warrant a second iteration of the CRF, ICRF2. The most recent ICRF3, was adopted by the IAU in 2018. However, due to the geographic distribution of observing stations being concentrated in the Northern hemisphere, CRFs are generally weaker in the South due to there being fewer Southern Hemisphere observations. To increase the Southern Hemisphere observations, and the density, precision of the sources, a series of deep South observing sessions was initiated in 1995. This initiative in 2004 became the IVS Celestial Reference Frame Deep South (IVS-CRDS) observing programme. This paper covers the evolution of the CRDS observing programme for the period 1995–2021, details the data products and results, and concludes with a summary of upcoming improvements to this ongoing project.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"80 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86211723","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. Duchesne, A. Thomson, J. Pritchard, E. Lenc, V. Moss, D. McConnell, M. Wieringa, M. Whiting, Z. Wang, Y. Wang, K. Rose, W. Raja, T. Murphy, J. Leung, M. Huynh, A. Hotan, T. Hodgson, G. Heald, SW Duchesne, Pritchard J Lenc E Thomson AJM
Abstract The Australian SKA Pathfinder (ASKAP) is being used to undertake a campaign to rapidly survey the sky in three frequency bands across its operational spectral range. The first pass of the Rapid ASKAP Continuum Survey (RACS) at 887.5 MHz in the low band has already been completed, with images, visibility datasets, and catalogues made available to the wider astronomical community through the CSIRO ASKAP Science Data Archive (CASDA). This work presents details of the second observing pass in the mid band at 1367.5 MHz, RACS-mid, and associated data release comprising images and visibility datasets covering the whole sky south of $delta_{text{J2000}}=+49^circ$ . This data release incorporates selective peeling to reduce artefacts around bright sources, as well as accurately modelled primary beam responses. The Stokes I images reach a median noise of 198 $mu$ Jy PSF $^{-1}$ with a declination-dependent angular resolution of 8.1–47.5 arcsec that fills a niche in the existing ecosystem of large-area astronomical surveys. We also supply Stokes V images after application of a widefield leakage correction, with a median noise of 165 $mu$ Jy PSF $^{-1}$ . We find the residual leakage of Stokes I into V to be $lesssim 0.9$ – $2.4$ % over the survey. This initial RACS-mid data release will be complemented by a future release comprising catalogues of the survey region. As with other RACS data releases, data products from this release will be made available through CASDA.
澳大利亚SKA探路者(ASKAP)正在进行一项运动，在其工作光谱范围内的三个频段内快速测量天空。快速ASKAP连续调查(RACS)在887.5 MHz低频段的第一次通过已经完成，图像，能见度数据集和目录通过CSIRO ASKAP科学数据档案(CASDA)向更广泛的天文界提供。本工作详细介绍了在1367.5 MHz中频的第二次观测通道，RACS-mid，以及相关的数据发布，包括覆盖$delta_{text{J2000}}=+49^circ$以南整个天空的图像和能见度数据集。该数据发布包含选择性剥离，以减少明亮光源周围的伪影，以及准确模拟主光束响应。Stokes I图像的中位噪声达到198 $mu$ Jy PSF $^{-1}$，与赤纬相关的角分辨率为8.1-47.5弧秒，填补了现有大面积天文调查生态系统中的空白。我们还提供了应用宽视场泄漏校正后的Stokes V图像，中值噪声为165 $mu$ Jy PSF $^{-1}$。我们发现Stokes I到V的剩余泄漏为$lesssim 0.9$ - $2.4$ % over the survey. This initial RACS-mid data release will be complemented by a future release comprising catalogues of the survey region. As with other RACS data releases, data products from this release will be made available through CASDA.
{"title":"The Rapid ASKAP Continuum Survey IV: continuum imaging at 1367.5 MHz and the first data release of RACS-mid","authors":"S. Duchesne, A. Thomson, J. Pritchard, E. Lenc, V. Moss, D. McConnell, M. Wieringa, M. Whiting, Z. Wang, Y. Wang, K. Rose, W. Raja, T. Murphy, J. Leung, M. Huynh, A. Hotan, T. Hodgson, G. Heald, SW Duchesne, Pritchard J Lenc E Thomson AJM","doi":"10.1017/pasa.2023.31","DOIUrl":"https://doi.org/10.1017/pasa.2023.31","url":null,"abstract":"Abstract The Australian SKA Pathfinder (ASKAP) is being used to undertake a campaign to rapidly survey the sky in three frequency bands across its operational spectral range. The first pass of the Rapid ASKAP Continuum Survey (RACS) at 887.5 MHz in the low band has already been completed, with images, visibility datasets, and catalogues made available to the wider astronomical community through the CSIRO ASKAP Science Data Archive (CASDA). This work presents details of the second observing pass in the mid band at 1367.5 MHz, RACS-mid, and associated data release comprising images and visibility datasets covering the whole sky south of \u0000$delta_{text{J2000}}=+49^circ$\u0000 . This data release incorporates selective peeling to reduce artefacts around bright sources, as well as accurately modelled primary beam responses. The Stokes I images reach a median noise of 198 \u0000$mu$\u0000 Jy PSF \u0000$^{-1}$\u0000 with a declination-dependent angular resolution of 8.1–47.5 arcsec that fills a niche in the existing ecosystem of large-area astronomical surveys. We also supply Stokes V images after application of a widefield leakage correction, with a median noise of 165 \u0000$mu$\u0000 Jy PSF \u0000$^{-1}$\u0000 . We find the residual leakage of Stokes I into V to be \u0000$lesssim 0.9$\u0000 – \u0000$2.4$\u0000 % over the survey. This initial RACS-mid data release will be complemented by a future release comprising catalogues of the survey region. As with other RACS data releases, data products from this release will be made available through CASDA.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"78 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76784886","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}
T. Reynolds, B. Catinella, L. Cortese, N. Deg, H. Denes, A. Elagali, B. For, P. Kamphuis, D. Kleiner, B. Koribalski, K. Lee-Waddell, C. Murugeshan, W. Raja, J. Rhee, K. Spekkens, L. Staveley-Smith, J. M. van der Hulst, J. Wang, T. Westmeier, O. I. Wong, F. Bigiel, A. Bosma, B. Holwerda, D. Leahy, M. Meyer
Abstract We investigate the diversity in the sizes and average surface densities of the neutral atomic hydrogen (H i) gas discs in $sim$ 280 nearby galaxies detected by the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY). We combine the uniformly observed, interferometric H i data from pilot observations of the Hydra cluster and NGC 4636 group fields with photometry measured from ultraviolet, optical, and near-infrared imaging surveys to investigate the interplay between stellar structure, star formation, and H i structural parameters. We quantify the H i structure by the size of the H i relative to the optical disc and the average H i surface density measured using effective and isodensity radii. For galaxies resolved by $>$ $1.3$ beams, we find that galaxies with higher stellar masses and stellar surface densities tend to have less extended H i discs and lower H i surface densities: the isodensity H i structural parameters show a weak negative dependence on stellar mass and stellar mass surface density. These trends strengthen when we limit our sample to galaxies resolved by $>$ 2 beams. We find that galaxies with higher H i surface densities and more extended H i discs tend to be more star forming: the isodensity H i structural parameters have stronger correlations with star formation. Normalising the H i disc size by the optical effective radius (instead of the isophotal radius) produces positive correlations with stellar masses and stellar surface densities and removes the correlations with star formation. This is due to the effective and isodensity H i radii increasing with mass at similar rates while, in the optical, the effective radius increases slower than the isophotal radius. Our results are in qualitative agreement with previous studies and demonstrate that with WALLABY we can begin to bridge the gap between small galaxy samples with high spatial resolution H i data and large, statistical studies using spatially unresolved, single-dish data.
{"title":"WALLABY pilot survey: The diversity of HI structural parameters in nearby galaxies","authors":"T. Reynolds, B. Catinella, L. Cortese, N. Deg, H. Denes, A. Elagali, B. For, P. Kamphuis, D. Kleiner, B. Koribalski, K. Lee-Waddell, C. Murugeshan, W. Raja, J. Rhee, K. Spekkens, L. Staveley-Smith, J. M. van der Hulst, J. Wang, T. Westmeier, O. I. Wong, F. Bigiel, A. Bosma, B. Holwerda, D. Leahy, M. Meyer","doi":"10.1017/pasa.2023.28","DOIUrl":"https://doi.org/10.1017/pasa.2023.28","url":null,"abstract":"Abstract We investigate the diversity in the sizes and average surface densities of the neutral atomic hydrogen (H i) gas discs in \u0000$sim$\u0000 280 nearby galaxies detected by the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY). We combine the uniformly observed, interferometric H i data from pilot observations of the Hydra cluster and NGC 4636 group fields with photometry measured from ultraviolet, optical, and near-infrared imaging surveys to investigate the interplay between stellar structure, star formation, and H i structural parameters. We quantify the H i structure by the size of the H i relative to the optical disc and the average H i surface density measured using effective and isodensity radii. For galaxies resolved by \u0000$>$\u0000 \u0000$1.3$\u0000 beams, we find that galaxies with higher stellar masses and stellar surface densities tend to have less extended H i discs and lower H i surface densities: the isodensity H i structural parameters show a weak negative dependence on stellar mass and stellar mass surface density. These trends strengthen when we limit our sample to galaxies resolved by \u0000$>$\u0000 2 beams. We find that galaxies with higher H i surface densities and more extended H i discs tend to be more star forming: the isodensity H i structural parameters have stronger correlations with star formation. Normalising the H i disc size by the optical effective radius (instead of the isophotal radius) produces positive correlations with stellar masses and stellar surface densities and removes the correlations with star formation. This is due to the effective and isodensity H i radii increasing with mass at similar rates while, in the optical, the effective radius increases slower than the isophotal radius. Our results are in qualitative agreement with previous studies and demonstrate that with WALLABY we can begin to bridge the gap between small galaxy samples with high spatial resolution H i data and large, statistical studies using spatially unresolved, single-dish data.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"9 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89620832","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}
K. Lee-Waddell, C. W. James, S. Ryder, E. Mahony, A. Bahramian, Baerbel Koribalski, Pravir Kumar, L. Marnoch, F. North-Hickey, E. Sadler, R. Shannon, N. Tejos, J. Thorne, J. Wang, R. Wayth
Abstract The putative host galaxy of FRB 20171020A was first identified as ESO 601-G036 in 2018, but as no repeat bursts have been detected, direct confirmation of the host remains elusive. In light of recent developments in the field, we re-examine this host and determine a new association confidence level of 98%. At 37 Mpc, this makes ESO 601-G036 the third closest FRB host galaxy to be identified to date and the closest to host an apparently non-repeating FRB (with an estimated repetition rate limit of $<$ $0.011$ bursts per day above $10^{39}$ erg). Due to its close distance, we are able to perform detailed multi-wavelength analysis on the ESO 601-G036 system. Follow-up observations confirm ESO 601-G036 to be a typical star-forming galaxy with H i and stellar masses of $log_{10}!(M_{rm{H,{small I}}} / M_odot) sim 9.2$ and $log_{10}!(M_star / M_odot) = 8.64^{+0.03}_{-0.15}$ , and a star formation rate of $text{SFR} = 0.09 pm 0.01,{rm M}_odot,text{yr}^{-1}$ . We detect, for the first time, a diffuse gaseous tail ( $log_{10}!(M_{rm{H,{small I}}} / M_odot) sim 8.3$ ) extending to the south-west that suggests recent interactions, likely with the confirmed nearby companion ESO 601-G037. ESO 601-G037 is a stellar shred located to the south of ESO 601-G036 that has an arc-like morphology, is about an order of magnitude less massive, and has a lower gas metallicity that is indicative of a younger stellar population. The properties of the ESO 601-G036 system indicate an ongoing minor merger event, which is affecting the overall gaseous component of the system and the stars within ESO 601-G037. Such activity is consistent with current FRB progenitor models involving magnetars and the signs of recent interactions in other nearby FRB host galaxies.
FRB 20171020A的假定宿主星系于2018年首次被确定为ESO 601-G036，但由于没有检测到重复爆发，因此直接确认宿主星系仍然难以捉摸。鉴于该领域最近的发展，我们重新审视这个宿主，并确定一个新的协会置信水平为98%. At 37 Mpc, this makes ESO 601-G036 the third closest FRB host galaxy to be identified to date and the closest to host an apparently non-repeating FRB (with an estimated repetition rate limit of $<$ $0.011$ bursts per day above $10^{39}$ erg). Due to its close distance, we are able to perform detailed multi-wavelength analysis on the ESO 601-G036 system. Follow-up observations confirm ESO 601-G036 to be a typical star-forming galaxy with H i and stellar masses of $log_{10}!(M_{rm{H,{small I}}} / M_odot) sim 9.2$ and $log_{10}!(M_star / M_odot) = 8.64^{+0.03}_{-0.15}$ , and a star formation rate of $text{SFR} = 0.09 pm 0.01,{rm M}_odot,text{yr}^{-1}$ . We detect, for the first time, a diffuse gaseous tail ( $log_{10}!(M_{rm{H,{small I}}} / M_odot) sim 8.3$ ) extending to the south-west that suggests recent interactions, likely with the confirmed nearby companion ESO 601-G037. ESO 601-G037 is a stellar shred located to the south of ESO 601-G036 that has an arc-like morphology, is about an order of magnitude less massive, and has a lower gas metallicity that is indicative of a younger stellar population. The properties of the ESO 601-G036 system indicate an ongoing minor merger event, which is affecting the overall gaseous component of the system and the stars within ESO 601-G037. Such activity is consistent with current FRB progenitor models involving magnetars and the signs of recent interactions in other nearby FRB host galaxies.
{"title":"The host galaxy of FRB 20171020A revisited","authors":"K. Lee-Waddell, C. W. James, S. Ryder, E. Mahony, A. Bahramian, Baerbel Koribalski, Pravir Kumar, L. Marnoch, F. North-Hickey, E. Sadler, R. Shannon, N. Tejos, J. Thorne, J. Wang, R. Wayth","doi":"10.1017/pasa.2023.27","DOIUrl":"https://doi.org/10.1017/pasa.2023.27","url":null,"abstract":"Abstract The putative host galaxy of FRB 20171020A was first identified as ESO 601-G036 in 2018, but as no repeat bursts have been detected, direct confirmation of the host remains elusive. In light of recent developments in the field, we re-examine this host and determine a new association confidence level of 98%. At 37 Mpc, this makes ESO 601-G036 the third closest FRB host galaxy to be identified to date and the closest to host an apparently non-repeating FRB (with an estimated repetition rate limit of \u0000$<$\u0000 \u0000$0.011$\u0000 bursts per day above \u0000$10^{39}$\u0000 erg). Due to its close distance, we are able to perform detailed multi-wavelength analysis on the ESO 601-G036 system. Follow-up observations confirm ESO 601-G036 to be a typical star-forming galaxy with H i and stellar masses of \u0000$log_{10}!(M_{rm{H,{small I}}} / M_odot) sim 9.2$\u0000 and \u0000$log_{10}!(M_star / M_odot) = 8.64^{+0.03}_{-0.15}$\u0000 , and a star formation rate of \u0000$text{SFR} = 0.09 pm 0.01,{rm M}_odot,text{yr}^{-1}$\u0000 . We detect, for the first time, a diffuse gaseous tail ( \u0000$log_{10}!(M_{rm{H,{small I}}} / M_odot) sim 8.3$\u0000 ) extending to the south-west that suggests recent interactions, likely with the confirmed nearby companion ESO 601-G037. ESO 601-G037 is a stellar shred located to the south of ESO 601-G036 that has an arc-like morphology, is about an order of magnitude less massive, and has a lower gas metallicity that is indicative of a younger stellar population. The properties of the ESO 601-G036 system indicate an ongoing minor merger event, which is affecting the overall gaseous component of the system and the stars within ESO 601-G037. Such activity is consistent with current FRB progenitor models involving magnetars and the signs of recent interactions in other nearby FRB host galaxies.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"49 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82740750","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}
N. Patra, R. Wayth, M. Sokolowski, D. Price, B. McKinley, D. Kenney
Abstract The report of a detection of an absorption profile centred at 78 MHz in the continuum radio background spectrum by the EDGES experiment and its interpretation as the redshifted 21 cm signal of cosmological origin has become one of the most debated results of observational cosmology in recent times. The cosmological 21 cm has long been proposed to be a powerful probe for observing the early Universe and tracing its evolution over cosmic time. Even though the science case is well established, measurement challenges posed on the technical ground are not fully understood to the level of claiming a successful detection. EDGES’s detection has naturally motivated a number of experimental attempts worldwide to corroborate the findings. In this paper, we present a precision cross-correlation spectrometer HYPEREION purpose-designed for a precision radio background measurement between 50–120 MHz to detect the absorption profile reported by the EDGES experiment. HYPEREION implements a pre-correlation signal processing technique that self-calibrates any spurious additive contamination from within the system and delivers a differential measurement of the sky spectrum and a reference thermal load internal to the system. This ensures an unambiguous ‘zero-point’ of absolute calibration of the purported absorption profile. We present the system design, measurement equations of the ideal system, systematic effects in the real system, and finally, an assessment of the real system output for the detection of the absorption profile at 78 MHz in the continuum radio background spectrum.
{"title":"HYPEREION—A precision system for the detection of the absorption profile centred at 78 MHz in the radio background spectrum","authors":"N. Patra, R. Wayth, M. Sokolowski, D. Price, B. McKinley, D. Kenney","doi":"10.1017/pasa.2023.25","DOIUrl":"https://doi.org/10.1017/pasa.2023.25","url":null,"abstract":"Abstract The report of a detection of an absorption profile centred at 78 MHz in the continuum radio background spectrum by the EDGES experiment and its interpretation as the redshifted 21 cm signal of cosmological origin has become one of the most debated results of observational cosmology in recent times. The cosmological 21 cm has long been proposed to be a powerful probe for observing the early Universe and tracing its evolution over cosmic time. Even though the science case is well established, measurement challenges posed on the technical ground are not fully understood to the level of claiming a successful detection. EDGES’s detection has naturally motivated a number of experimental attempts worldwide to corroborate the findings. In this paper, we present a precision cross-correlation spectrometer HYPEREION purpose-designed for a precision radio background measurement between 50–120 MHz to detect the absorption profile reported by the EDGES experiment. HYPEREION implements a pre-correlation signal processing technique that self-calibrates any spurious additive contamination from within the system and delivers a differential measurement of the sky spectrum and a reference thermal load internal to the system. This ensures an unambiguous ‘zero-point’ of absolute calibration of the purported absorption profile. We present the system design, measurement equations of the ideal system, systematic effects in the real system, and finally, an assessment of the real system output for the detection of the absorption profile at 78 MHz in the continuum radio background spectrum.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"14 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73320569","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}
M. Boyce, A. Hopkins, S. Riggi, L. Rudnick, M. Ramsay, C. Hale, J. Marvil, M. Whiting, P. Venkataraman, C. O’Dea, S. Baum, Y. Gordon, A. Vantyghem, M. Dionyssiou, H. Andernach, J. Collier, J. English, B. Koribalski, D. Leahy, M. Michałowski, S. Safi-Harb, M. Vaccari, Elaine L. Alexander, M. Cowley, A. Kapinska, A. Robotham, H. Tang
Abstract We present a comparison between the performance of a selection of source finders (SFs) using a new software tool called Hydra. The companion paper, Paper I, introduced the Hydra tool and demonstrated its performance using simulated data. Here we apply Hydra to assess the performance of different source finders by analysing real observational data taken from the Evolutionary Map of the Universe (EMU) Pilot Survey. EMU is a wide-field radio continuum survey whose primary goal is to make a deep ( $20mu$ Jy/beam RMS noise), intermediate angular resolution ( $15^{primeprime}$ ), 1 GHz survey of the entire sky south of $+30^{circ}$ declination, and expecting to detect and catalogue up to 40 million sources. With the main EMU survey it is highly desirable to understand the performance of radio image SF software and to identify an approach that optimises source detection capabilities. Hydra has been developed to refine this process, as well as to deliver a range of metrics and source finding data products from multiple SFs. We present the performance of the five SFs tested here in terms of their completeness and reliability statistics, their flux density and source size measurements, and an exploration of case studies to highlight finder-specific limitations.
{"title":"Hydra II: Characterisation of Aegean, Caesar, ProFound, PyBDSF, and Selavy source finders","authors":"M. Boyce, A. Hopkins, S. Riggi, L. Rudnick, M. Ramsay, C. Hale, J. Marvil, M. Whiting, P. Venkataraman, C. O’Dea, S. Baum, Y. Gordon, A. Vantyghem, M. Dionyssiou, H. Andernach, J. Collier, J. English, B. Koribalski, D. Leahy, M. Michałowski, S. Safi-Harb, M. Vaccari, Elaine L. Alexander, M. Cowley, A. Kapinska, A. Robotham, H. Tang","doi":"10.1017/pasa.2023.29","DOIUrl":"https://doi.org/10.1017/pasa.2023.29","url":null,"abstract":"Abstract We present a comparison between the performance of a selection of source finders (SFs) using a new software tool called Hydra. The companion paper, Paper I, introduced the Hydra tool and demonstrated its performance using simulated data. Here we apply Hydra to assess the performance of different source finders by analysing real observational data taken from the Evolutionary Map of the Universe (EMU) Pilot Survey. EMU is a wide-field radio continuum survey whose primary goal is to make a deep ( \u0000$20mu$\u0000 Jy/beam RMS noise), intermediate angular resolution ( \u0000$15^{primeprime}$\u0000 ), 1 GHz survey of the entire sky south of \u0000$+30^{circ}$\u0000 declination, and expecting to detect and catalogue up to 40 million sources. With the main EMU survey it is highly desirable to understand the performance of radio image SF software and to identify an approach that optimises source detection capabilities. Hydra has been developed to refine this process, as well as to deliver a range of metrics and source finding data products from multiple SFs. We present the performance of the five SFs tested here in terms of their completeness and reliability statistics, their flux density and source size measurements, and an exploration of case studies to highlight finder-specific limitations.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"17 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84645737","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}
M. Boyce, A. Hopkins, S. Riggi, L. Rudnick, M. Ramsay, C. Hale, J. Marvil, M. Whiting, P. Venkataraman, C. O’Dea, S. Baum, Y. Gordon, A. Vantyghem, M. Dionyssiou, H. Andernach, J. Collier, J. English, B. Koribalski, D. Leahy, M. Michałowski, S. Safi-Harb, M. Vaccari, Elaine L. Alexander, M. Cowley, A. Kapinska, A. Robotham, H. Tang
Abstract The latest generation of radio surveys are now producing sky survey images containing many millions of radio sources. In this context it is highly desirable to understand the performance of radio image source finder (SF) software and to identify an approach that optimises source detection capabilities. We have created Hydra to be an extensible multi-SF and cataloguing tool that can be used to compare and evaluate different SFs. Hydra, which currently includes the SFs Aegean, Caesar, ProFound, PyBDSF, and Selavy, provides for the addition of new SFs through containerisation and configuration files. The SF input RMS noise and island parameters are optimised to a 90% ‘percentage real detections’ threshold (calculated from the difference between detections in the real and inverted images), to enable comparison between SFs. Hydra provides completeness and reliability diagnostics through observed-deep ( $mathcal{D}$ ) and generated-shallow ( $mathcal{S}$ ) images, as well as other statistics. In addition, it has a visual inspection tool for comparing residual images through various selection filters, such as S/N bins in completeness or reliability. The tool allows the user to easily compare and evaluate different SFs in order to choose their desired SF, or a combination thereof. This paper is part one of a two part series. In this paper we introduce the Hydra software suite and validate its $mathcal{D/S}$ metrics using simulated data. The companion paper demonstrates the utility of Hydra by comparing the performance of SFs using both simulated and real images.
{"title":"Hydra I: An extensible multi-source-finder comparison and cataloguing tool","authors":"M. Boyce, A. Hopkins, S. Riggi, L. Rudnick, M. Ramsay, C. Hale, J. Marvil, M. Whiting, P. Venkataraman, C. O’Dea, S. Baum, Y. Gordon, A. Vantyghem, M. Dionyssiou, H. Andernach, J. Collier, J. English, B. Koribalski, D. Leahy, M. Michałowski, S. Safi-Harb, M. Vaccari, Elaine L. Alexander, M. Cowley, A. Kapinska, A. Robotham, H. Tang","doi":"10.1017/pasa.2023.24","DOIUrl":"https://doi.org/10.1017/pasa.2023.24","url":null,"abstract":"Abstract The latest generation of radio surveys are now producing sky survey images containing many millions of radio sources. In this context it is highly desirable to understand the performance of radio image source finder (SF) software and to identify an approach that optimises source detection capabilities. We have created Hydra to be an extensible multi-SF and cataloguing tool that can be used to compare and evaluate different SFs. Hydra, which currently includes the SFs Aegean, Caesar, ProFound, PyBDSF, and Selavy, provides for the addition of new SFs through containerisation and configuration files. The SF input RMS noise and island parameters are optimised to a 90% ‘percentage real detections’ threshold (calculated from the difference between detections in the real and inverted images), to enable comparison between SFs. Hydra provides completeness and reliability diagnostics through observed-deep ( \u0000$mathcal{D}$\u0000 ) and generated-shallow ( \u0000$mathcal{S}$\u0000 ) images, as well as other statistics. In addition, it has a visual inspection tool for comparing residual images through various selection filters, such as S/N bins in completeness or reliability. The tool allows the user to easily compare and evaluate different SFs in order to choose their desired SF, or a combination thereof. This paper is part one of a two part series. In this paper we introduce the Hydra software suite and validate its \u0000$mathcal{D/S}$\u0000 metrics using simulated data. The companion paper demonstrates the utility of Hydra by comparing the performance of SFs using both simulated and real images.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"10 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77952160","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}
K. Gigoyan, A. Sarkissian, G. Kostandyan, K. Gigoyan, M. Meftah, S. Bekki, N. Azatyan, F. Zamkotsian
Abstract In order to gain more information on the 236 M dwarfs identified in the First Byurakan Survey (FBS) low-resolution (lr) spectroscopic database, Gaia EDR3 high-accuracy astrometric and photometric data and Transiting Exoplanet Survey Satellite (TESS) data are used to characterise these M dwarfs and their possible multiplicity. Among the sample of 236 relatively bright $(7.3 < K_S < 14.4)$ M dwarfs, 176 are new discoveries. The Gaia EDR3 G broadband magnitudes are in the range $11.3 < G < 17.1$ . New distance information based on the EDR3 parallaxes are used to estimate the G-band absolute magnitudes. Nine FBS M dwarfs out of 176 newly discovered lie within 25 pc of the Sun. The FBS 0909-082 is the most distant $(r=780$ pc) M dwarf of the analysed sample, with a G-band absolute magnitude $M(G) = 9.18$ , $M = 0.59$ M $_{odot}$ , $L = 0.13597$ L $_{odot}$ , and $T_{eff}$ = 3844 K; it can be classified as M1 - M2 subtype dwarf. The nearest is FBS 0250+167, a M7 subtype dwarf located at 3.83 pc from the Sun with a very high proper motion (5.13 arcsec yr $^{-1}$ ). The TESS estimated masses lie in the range 0.095 ( $pm$ 0.02) M $_{odot}leq$ $Mleq$ 0.7 ( $pm$ 0.1) M $_{odot}$ and $T_{eff}$ in the range 4000 K < $T_{eff}$ < 2790 K. We analyse colour-colour and colour-absolute magnitude diagram (CaMD) diagrams for the M dwarfs. Results suggest that 27 FBS M dwarfs are double or multiple systems. The observed spectral energy distribution (SED) for some of the M dwarfs can be used to classify potential infrared excess. Using TESS light curves, flares are detected for some FBS M dwarfs. Finally, for early and late sub-classes of the M dwarfs, the detection range for survey is estimated for the first time.
摘要:为了获得更多关于第一次比拉坎巡天(FBS)低分辨率光谱数据库中发现的236颗M矮星的信息，利用盖亚EDR3高精度天体测量和光度测量数据和凌日系外行星巡天卫星(TESS)数据对这些M矮星及其可能的多样性进行了表征。在236个相对明亮的$(7.3 < K_S < 14.4)$ M矮星样本中，有176个是新发现的。盖亚edr3g宽带星等在$11.3 < G < 17.1$范围内。基于EDR3视差的新距离信息被用于估计g波段的绝对星等。在新发现的176颗FBS M矮星中，有9颗位于距离太阳25％的范围内。FBS 0909-082是分析样本中距离最远的$(r=780$ pc) M矮星，其g波段绝对星等为$M(G) = 9.18$、$M = 0.59$ M $_{odot}$、$L = 0.13597$ L $_{odot}$和$T_{eff}$ = 3844 K;可归类为M1 - M2型矮星。最近的是FBS 0250+167，一颗M7亚型矮星，距离太阳3.83 pc，具有非常高的固有运动(5.13弧秒/年$^{-1}$)。TESS的估计质量范围为0.095 ($pm$ 0.02) M $_{odot}leq$$Mleq$ 0.7 ($pm$ 0.1) M $_{odot}$和$T_{eff}$，范围为4000 K < $T_{eff}$ < 2790 K。我们分析了M矮星的色-色和色-绝对星等图(CaMD)。结果表明，27颗FBS M矮星是双系统或多系统。观测到的一些M矮星的光谱能量分布(SED)可以用来对潜在的红外过剩进行分类。利用TESS光曲线，可以探测到一些FBS M矮星的耀斑。最后，首次估算了M矮星早期和晚期亚类的探测距离。
{"title":"M dwarfs found in the first Byurakan spectral sky survey database. Gaia EDR3 and TESS data. Some preliminary results","authors":"K. Gigoyan, A. Sarkissian, G. Kostandyan, K. Gigoyan, M. Meftah, S. Bekki, N. Azatyan, F. Zamkotsian","doi":"10.1017/pasa.2023.20","DOIUrl":"https://doi.org/10.1017/pasa.2023.20","url":null,"abstract":"Abstract In order to gain more information on the 236 M dwarfs identified in the First Byurakan Survey (FBS) low-resolution (lr) spectroscopic database, Gaia EDR3 high-accuracy astrometric and photometric data and Transiting Exoplanet Survey Satellite (TESS) data are used to characterise these M dwarfs and their possible multiplicity. Among the sample of 236 relatively bright \u0000$(7.3 < K_S < 14.4)$\u0000 M dwarfs, 176 are new discoveries. The Gaia EDR3 G broadband magnitudes are in the range \u0000$11.3 < G < 17.1$\u0000 . New distance information based on the EDR3 parallaxes are used to estimate the G-band absolute magnitudes. Nine FBS M dwarfs out of 176 newly discovered lie within 25 pc of the Sun. The FBS 0909-082 is the most distant \u0000$(r=780$\u0000 pc) M dwarf of the analysed sample, with a G-band absolute magnitude \u0000$M(G) = 9.18$\u0000 , \u0000$M = 0.59$\u0000 M \u0000$_{odot}$\u0000 , \u0000$L = 0.13597$\u0000 L \u0000$_{odot}$\u0000 , and \u0000$T_{eff}$\u0000 = 3844 K; it can be classified as M1 - M2 subtype dwarf. The nearest is FBS 0250+167, a M7 subtype dwarf located at 3.83 pc from the Sun with a very high proper motion (5.13 arcsec yr \u0000$^{-1}$\u0000 ). The TESS estimated masses lie in the range 0.095 ( \u0000$pm$\u0000 0.02) M \u0000$_{odot}leq$\u0000 \u0000$Mleq$\u0000 0.7 ( \u0000$pm$\u0000 0.1) M \u0000$_{odot}$\u0000 and \u0000$T_{eff}$\u0000 in the range 4000 K < \u0000$T_{eff}$\u0000 < 2790 K. We analyse colour-colour and colour-absolute magnitude diagram (CaMD) diagrams for the M dwarfs. Results suggest that 27 FBS M dwarfs are double or multiple systems. The observed spectral energy distribution (SED) for some of the M dwarfs can be used to classify potential infrared excess. Using TESS light curves, flares are detected for some FBS M dwarfs. Finally, for early and late sub-classes of the M dwarfs, the detection range for survey is estimated for the first time.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"25 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74647154","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}
Abstract Close galaxy flybys, interactions during which two galaxies inter-penetrate, are frequent and can significantly affect the evolution of individual galaxies. Equal-mass flybys are extremely rare and almost exclusively distant, while frequent flybys have mass ratios $q=0.1$ or lower, with a secondary galaxy penetrating deep into the primary. This can result in comparable strengths of interaction between the two classes of flybys and lead to essentially the same effects. To demonstrate this, emphasise and explore the role of the impact parameter further, we performed a series of N-body simulations of typical flybys with varying relative impact parameters $b/R_{mathrm{vir},1}$ ranging from $0.114$ to $0.272$ of the virial radius of the primary galaxy. Two-armed spirals form during flybys, with radii of origin correlated with the impact parameter and strengths well approximated with an inverted S-curve. The impact parameter does not affect the shape of induced spirals, and the lifetimes of a distinguished spiral structure appear to be constant, $T_mathrm{LF} sim 2$ Gyr. Bars, with strengths anti-correlated with the impact parameter, form after the encounter is over in simulations with $b/R_{mathrm{vir},1} leq 0.178$ and interaction strengths $Sgeq0.076$ , but they are short-lived except for the stronger interactions with $Sgeq0.129$ . We showcase an occurrence of multiple structures (ring-like, double bar) that survives for an exceptionally long time in one of the simulations. Effects on the pre-existing bar instability, that develops much later, are diverse: from an acceleration of bar formation, little to no effect, to even bar suppression. There is no uniform correlation between these effects and the impact parameter, as they are secondary effects, happening later in a post-flyby stage. Classical bulges are resilient to flyby interactions, while dark matter halos can significantly spin up in the amount anti-correlated with the impact parameter. There is an offset angle between the angular momentum vector of the dark matter halo and that of a disc, and it correlates linearly with the impact parameter. Thus, flybys remain an important pathway for structural evolution within galaxies in the local Universe.
{"title":"The role of impact parameter in typical close galaxy flybys","authors":"A. Mitrašinović, M. Micic","doi":"10.1017/pasa.2023.23","DOIUrl":"https://doi.org/10.1017/pasa.2023.23","url":null,"abstract":"Abstract Close galaxy flybys, interactions during which two galaxies inter-penetrate, are frequent and can significantly affect the evolution of individual galaxies. Equal-mass flybys are extremely rare and almost exclusively distant, while frequent flybys have mass ratios \u0000$q=0.1$\u0000 or lower, with a secondary galaxy penetrating deep into the primary. This can result in comparable strengths of interaction between the two classes of flybys and lead to essentially the same effects. To demonstrate this, emphasise and explore the role of the impact parameter further, we performed a series of N-body simulations of typical flybys with varying relative impact parameters \u0000$b/R_{mathrm{vir},1}$\u0000 ranging from \u0000$0.114$\u0000 to \u0000$0.272$\u0000 of the virial radius of the primary galaxy. Two-armed spirals form during flybys, with radii of origin correlated with the impact parameter and strengths well approximated with an inverted S-curve. The impact parameter does not affect the shape of induced spirals, and the lifetimes of a distinguished spiral structure appear to be constant, \u0000$T_mathrm{LF} sim 2$\u0000 Gyr. Bars, with strengths anti-correlated with the impact parameter, form after the encounter is over in simulations with \u0000$b/R_{mathrm{vir},1} leq 0.178$\u0000 and interaction strengths \u0000$Sgeq0.076$\u0000 , but they are short-lived except for the stronger interactions with \u0000$Sgeq0.129$\u0000 . We showcase an occurrence of multiple structures (ring-like, double bar) that survives for an exceptionally long time in one of the simulations. Effects on the pre-existing bar instability, that develops much later, are diverse: from an acceleration of bar formation, little to no effect, to even bar suppression. There is no uniform correlation between these effects and the impact parameter, as they are secondary effects, happening later in a post-flyby stage. Classical bulges are resilient to flyby interactions, while dark matter halos can significantly spin up in the amount anti-correlated with the impact parameter. There is an offset angle between the angular momentum vector of the dark matter halo and that of a disc, and it correlates linearly with the impact parameter. Thus, flybys remain an important pathway for structural evolution within galaxies in the local Universe.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"40 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81879462","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}
Abstract A new determination of the temperature of the intergalactic medium (IGM) over $3.9 leq z leq 4.3$ is presented. We applied the curvature method on a sample of 10 high-resolution quasar spectra from the Ultraviolet and Visual Echelle Spectrograph on the VLT/ESO. We measured the temperature at mean density by determining the temperature at the characteristic overdensity, which is tight function of the absolute curvature irrespective of $unicode{x03B3}$ . Under the assumption of fiducial value of $unicode{x03B3} = 1.4$ , we determined the values of temperatures at mean density $T_{0} = 7893^{+1417}_{-1226}$ K and $T_{0} = 8153^{+1224}_{-993}$ K for redshift range of $3.9 leq z leq 4.1$ and $4.1 leq z leq 4.3$ , respectively. Even though the results show no strong temperature evolution over the studied redshift range, our measurements are consistent with an IGM thermal history that includes a contribution from He ii reionisation.
提出了一种新的测定$3.9 leq z leq 4.3$上星系间介质(IGM)温度的方法。我们将曲率方法应用于VLT/ESO上的10个高分辨率类星体光谱样本的紫外和视觉梯队光谱仪。我们通过确定特征过密度的温度来测量平均密度下的温度，这是绝对曲率的紧密函数，与$unicode{x03B3}$无关。假设基准值为$unicode{x03B3} = 1.4$，我们分别确定了红移范围为$3.9 leq z leq 4.1$和$4.1 leq z leq 4.3$的平均密度温度值$T_{0} = 7893^{+1417}_{-1226}$ K和$T_{0} = 8153^{+1224}_{-993}$ K。尽管结果显示在研究的红移范围内没有强烈的温度演化，但我们的测量结果与包括He ii再电离贡献的IGM热历史一致。
{"title":"The thermal history of the intergalactic medium at 3.9 ≤ z ≤ 4.3","authors":"T. Ondro, R. Gális","doi":"10.1017/pasa.2023.22","DOIUrl":"https://doi.org/10.1017/pasa.2023.22","url":null,"abstract":"Abstract A new determination of the temperature of the intergalactic medium (IGM) over \u0000$3.9 leq z leq 4.3$\u0000 is presented. We applied the curvature method on a sample of 10 high-resolution quasar spectra from the Ultraviolet and Visual Echelle Spectrograph on the VLT/ESO. We measured the temperature at mean density by determining the temperature at the characteristic overdensity, which is tight function of the absolute curvature irrespective of \u0000$unicode{x03B3}$\u0000 . Under the assumption of fiducial value of \u0000$unicode{x03B3} = 1.4$\u0000 , we determined the values of temperatures at mean density \u0000$T_{0} = 7893^{+1417}_{-1226}$\u0000 K and \u0000$T_{0} = 8153^{+1224}_{-993}$\u0000 K for redshift range of \u0000$3.9 leq z leq 4.1$\u0000 and \u0000$4.1 leq z leq 4.3$\u0000 , respectively. Even though the results show no strong temperature evolution over the studied redshift range, our measurements are consistent with an IGM thermal history that includes a contribution from He ii reionisation.","PeriodicalId":20753,"journal":{"name":"Publications of the Astronomical Society of Australia","volume":"63 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74094128","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}
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