Pub Date : 2024-03-27DOI: 10.1088/1538-3873/ad31c9
Pablo López
It is usually assumed that the angular momentum (AM) of dark matter halos arises during the linear stages of structure formation, as a consequence of the coupling between the proto-haloes’ shape and the tidal field produced by their surrounding density perturbations. This approach, known as linear tidal torque theory (TTT), has been shown to make fairly good predictions about the mean evolution of both the AM amplitude and orientation up to approximately the time when the proto-haloes collapse. After this point, proto-haloes are increasingly affected by nonlinear processes that are not taken into account by the model. However, it has been seen in numerical simulations that, even at very early stages, the AM of proto-haloes is systematically reoriented toward perpendicularity with respect to the forming cosmic filaments, in contradiction with the fixed direction expected from the TTT. In this work we present a novel analytical approach that introduces an anisotropic scaling factor to the standard TTT equations, which allows the AM orientation to change in time, even during the linear regime. The amplitude and direction of this shift depend on the large scale tidal field around the forming proto-haloes. Our results significantly improve the predictions for the AM direction up to the time of protohalo collapse and, in some cases, even further in time.
通常的假设是，暗物质光环的角动量（AM）产生于结构形成的线性阶段，是原光环的形状与其周围密度扰动所产生的潮汐场之间耦合的结果。这种方法被称为线性潮汐力矩理论（TTT），已被证明可以很好地预测 AM 振幅和方向的平均演化，直至原初光环坍缩为止。在此之后，原螺旋会越来越多地受到非线性过程的影响，而这些过程并没有被模型考虑在内。然而，我们在数值模拟中发现，即使在很早的阶段，原恒星的AM方向也会系统地调整为与正在形成的宇宙丝垂直，这与TTT所预期的固定方向是矛盾的。在这项工作中，我们提出了一种新颖的分析方法，即在标准 TTT 方程中引入各向异性的缩放因子，从而使 AM 方向随时间发生变化，即使在线性状态下也是如此。这种变化的幅度和方向取决于正在形成的原海泡石周围的大尺度潮汐场。我们的结果极大地改进了对 AM 方向的预测，直至原光环坍缩之时，在某些情况下，甚至在时间上更进一步。
{"title":"Early Evolution of Spin Direction in Dark Matter Halos and the Effect of the Surrounding Large-scale Tidal Field* * Thesis work conducted at Facultad de Matemática, Astronomía, Física y Computación, Universidad Nacional de Córdoba, Córdoba, Argentina. † † PhD Thesis directed by Manuel Merchán; PhD Degree awarded 2023 July 31.","authors":"Pablo López","doi":"10.1088/1538-3873/ad31c9","DOIUrl":"https://doi.org/10.1088/1538-3873/ad31c9","url":null,"abstract":"It is usually assumed that the angular momentum (AM) of dark matter halos arises during the linear stages of structure formation, as a consequence of the coupling between the proto-haloes’ shape and the tidal field produced by their surrounding density perturbations. This approach, known as linear tidal torque theory (TTT), has been shown to make fairly good predictions about the mean evolution of both the AM amplitude and orientation up to approximately the time when the proto-haloes collapse. After this point, proto-haloes are increasingly affected by nonlinear processes that are not taken into account by the model. However, it has been seen in numerical simulations that, even at very early stages, the AM of proto-haloes is systematically reoriented toward perpendicularity with respect to the forming cosmic filaments, in contradiction with the fixed direction expected from the TTT. In this work we present a novel analytical approach that introduces an anisotropic scaling factor to the standard TTT equations, which allows the AM orientation to change in time, even during the linear regime. The amplitude and direction of this shift depend on the large scale tidal field around the forming proto-haloes. Our results significantly improve the predictions for the AM direction up to the time of protohalo collapse and, in some cases, even further in time.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"39 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314680","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}
Pub Date : 2024-03-27DOI: 10.1088/1538-3873/ad2e11
Gabriele Coppi, Simon Dicker, James E. Aguirre, Jason E. Austermann, James A. Beall, Susan E. Clark, Erin G. Cox, Mark J. Devlin, Laura M. Fissel, Nicholas Galitzki, Brandon S. Hensley, Johannes Hubmayr, Sergio Molinari, Federico Nati, Giles Novak, Eugenio Schisano, Juan D. Soler, Carole E. Tucker, Joel N. Ullom, Anna Vaskuri, Michael R. Vissers, Jordan D. Wheeler, Mario Zannoni, (The BLAST Observatory Collaboration)
Sensitive wide-field observations of polarized thermal emission from interstellar dust grains will allow astronomers to address key outstanding questions about the life cycle of matter and energy driving the formation of stars and the evolution of galaxies. Stratospheric balloon-borne telescopes can map this polarized emission at far-infrared wavelengths near the peak of the dust thermal spectrum—wavelengths that are inaccessible from the ground. In this paper we address the sensitivity achievable by a Super Pressure Balloon polarimetry mission, using as an example the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) Observatory. By launching from Wanaka, New Zealand, the BLAST Observatory can obtain a 30 days flight with excellent sky coverage—overcoming limitations of past experiments that suffered from short flight duration and/or launch sites with poor coverage of nearby star-forming regions. This proposed polarimetry mission will map large regions of the sky at sub-arcminute resolution, with simultaneous observations at 175, 250, and 350 μm, using a total of 8274 microwave kinetic inductance detectors. Here, we describe the scientific motivation for the BLAST Observatory, the proposed implementation, and the forecasting methods used to predict its sensitivity. We also compare our forecasted experiment sensitivity with other facilities.
{"title":"The BLAST Observatory: A Sensitivity Study for Far-IR Balloon-borne Polarimeters","authors":"Gabriele Coppi, Simon Dicker, James E. Aguirre, Jason E. Austermann, James A. Beall, Susan E. Clark, Erin G. Cox, Mark J. Devlin, Laura M. Fissel, Nicholas Galitzki, Brandon S. Hensley, Johannes Hubmayr, Sergio Molinari, Federico Nati, Giles Novak, Eugenio Schisano, Juan D. Soler, Carole E. Tucker, Joel N. Ullom, Anna Vaskuri, Michael R. Vissers, Jordan D. Wheeler, Mario Zannoni, (The BLAST Observatory Collaboration)","doi":"10.1088/1538-3873/ad2e11","DOIUrl":"https://doi.org/10.1088/1538-3873/ad2e11","url":null,"abstract":"Sensitive wide-field observations of polarized thermal emission from interstellar dust grains will allow astronomers to address key outstanding questions about the life cycle of matter and energy driving the formation of stars and the evolution of galaxies. Stratospheric balloon-borne telescopes can map this polarized emission at far-infrared wavelengths near the peak of the dust thermal spectrum—wavelengths that are inaccessible from the ground. In this paper we address the sensitivity achievable by a Super Pressure Balloon polarimetry mission, using as an example the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) Observatory. By launching from Wanaka, New Zealand, the BLAST Observatory can obtain a 30 days flight with excellent sky coverage—overcoming limitations of past experiments that suffered from short flight duration and/or launch sites with poor coverage of nearby star-forming regions. This proposed polarimetry mission will map large regions of the sky at sub-arcminute resolution, with simultaneous observations at 175, 250, and 350 <italic toggle=\"yes\">μ</italic>m, using a total of 8274 microwave kinetic inductance detectors. Here, we describe the scientific motivation for the BLAST Observatory, the proposed implementation, and the forecasting methods used to predict its sensitivity. We also compare our forecasted experiment sensitivity with other facilities.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"138 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314705","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}
Pub Date : 2024-03-19DOI: 10.1088/1538-3873/ad23fc
Chengxing Zhai, Michael Shao, Navtej Saini, Philip Choi, Nez Evans, Russell Trahan, Kutay Nazli, Max Zhan
Synthetic tracking (ST) has emerged as a potent technique for observing fast-moving near-Earth objects (NEOs), offering enhanced detection sensitivity and astrometric accuracy by avoiding trailing loss. This approach also empowers small telescopes to use prolonged integration times to achieve high sensitivity for NEO surveys and follow-up observations. In this study, we present the outcomes of ST observations conducted with Pomona College’s 1 m telescope at the Table Mountain Facility and JPL’s robotic telescopes at the Sierra Remote Observatory. The results showcase astrometric accuracy statistics comparable to stellar astrometry, irrespective of an object’s rate of motion, and the capability to detect faint asteroids beyond 20.5th magnitude using 11 inch telescopes. Furthermore, we detail the technical aspects of data processing, including the correction of differential chromatic refraction in the atmosphere and accurate timing for image stacking, which contribute to achieving precise astrometry. We also provide compelling examples that showcase the robustness of ST even when asteroids closely approach stars or bright satellites cause disturbances. Moreover, we illustrate the proficiency of ST in recovering NEO candidates with highly uncertain ephemerides. As a glimpse of the potential of NEO surveys utilizing small robotic telescopes with ST, we present significant statistics from our NEO survey conducted for testing purposes. These findings underscore the promise and effectiveness of ST as a powerful tool for observing fast-moving NEOs, offering valuable insights into their trajectories and characteristics. Overall, the adoption of ST stands to revolutionize fast-moving NEO observations for planetary defense and studying these celestial bodies.
合成跟踪（ST）已成为观测快速移动近地天体（NEOs）的一种有效技术，它通过避免拖尾损失提高了探测灵敏度和天体测量精度。这种方法还使小型望远镜能够利用较长的积分时间来实现近地天体巡天和跟踪观测的高灵敏度。在本研究中，我们介绍了利用波莫纳学院在桌山设施的 1 米望远镜和 JPL 在 Sierra Remote Observatory 的机器人望远镜进行 ST 观测的结果。观测结果表明，无论天体的运动速度如何，天体测量的精确度统计都可与恒星天体测量相媲美，而且使用 11 英寸望远镜还能探测到 20.5 等以上的暗小行星。此外，我们还详细介绍了数据处理技术方面的问题，包括大气层中色差折射的校正和图像叠加的精确计时，这些都有助于实现精确的天体测量。我们还提供了令人信服的示例，展示了 ST 即使在小行星接近恒星或明亮卫星造成干扰时的稳健性。此外，我们还展示了 ST 在星历表高度不确定的情况下恢复近地天体候选星的能力。作为利用带有 ST 的小型机器人望远镜进行近地天体测量的潜力一瞥，我们展示了为测试目的而进行的近地天体测量的重要统计数据。这些发现强调了 ST 作为观测快速移动近地天体的强大工具的前景和有效性，为了解近地天体的轨迹和特征提供了宝贵的信息。总之，ST 的采用将彻底改变用于行星防御和研究这些天体的快速移动近地天体观测。
{"title":"Near-Earth Object Observations using Synthetic Tracking","authors":"Chengxing Zhai, Michael Shao, Navtej Saini, Philip Choi, Nez Evans, Russell Trahan, Kutay Nazli, Max Zhan","doi":"10.1088/1538-3873/ad23fc","DOIUrl":"https://doi.org/10.1088/1538-3873/ad23fc","url":null,"abstract":"Synthetic tracking (ST) has emerged as a potent technique for observing fast-moving near-Earth objects (NEOs), offering enhanced detection sensitivity and astrometric accuracy by avoiding trailing loss. This approach also empowers small telescopes to use prolonged integration times to achieve high sensitivity for NEO surveys and follow-up observations. In this study, we present the outcomes of ST observations conducted with Pomona College’s 1 m telescope at the Table Mountain Facility and JPL’s robotic telescopes at the Sierra Remote Observatory. The results showcase astrometric accuracy statistics comparable to stellar astrometry, irrespective of an object’s rate of motion, and the capability to detect faint asteroids beyond 20.5th magnitude using 11 inch telescopes. Furthermore, we detail the technical aspects of data processing, including the correction of differential chromatic refraction in the atmosphere and accurate timing for image stacking, which contribute to achieving precise astrometry. We also provide compelling examples that showcase the robustness of ST even when asteroids closely approach stars or bright satellites cause disturbances. Moreover, we illustrate the proficiency of ST in recovering NEO candidates with highly uncertain ephemerides. As a glimpse of the potential of NEO surveys utilizing small robotic telescopes with ST, we present significant statistics from our NEO survey conducted for testing purposes. These findings underscore the promise and effectiveness of ST as a powerful tool for observing fast-moving NEOs, offering valuable insights into their trajectories and characteristics. Overall, the adoption of ST stands to revolutionize fast-moving NEO observations for planetary defense and studying these celestial bodies.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"33 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314625","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}
Pub Date : 2024-03-19DOI: 10.1088/1538-3873/ad2551
Mattia Libralato, Ioannis Argyriou, Dan Dicken, Macarena García Marín, Pierre Guillard, Dean C. Hines, Patrick J. Kavanagh, Sarah Kendrew, David R. Law, Alberto Noriega-Crespo, Javier Álvarez-Márquez
Astrometry is one of the main pillars of astronomy, and one of its oldest branches. Over the years, an increasing number of astrometric works by means of Hubble Space Telescope (HST) data have revolutionized our understanding of various phenomena. With the launch of JWST, it becomes almost instinctive to want to replicate or improve these results with data taken with the newest, state-of-the-art, space-based telescope. In this regard, the initial focus of the community has been on the Near-Infrared detectors on board of JWST because of their high spatial resolution. This paper begins the effort to capture and apply what has been learned from HST to the Mid-InfraRed Instrument (MIRI) of JWST by developing the tools to obtain high-precision astrometry and photometry with its imager. We describe in detail how to create accurate effective point-spread-function (ePSF) models and geometric-distortion corrections, analyze their temporal stability, and test their quality to the extent of what is currently possible with the available data in the JWST MAST archive. We show that careful data reduction provides deep insight on the performance and intricacies of the MIRI imager, and of JWST in general. In an effort to help the community devise new observing programs, we make our ePSF models and geometric-distortion corrections publicly available.
{"title":"High-precision Astrometry and Photometry with the JWST/MIRI Imager","authors":"Mattia Libralato, Ioannis Argyriou, Dan Dicken, Macarena García Marín, Pierre Guillard, Dean C. Hines, Patrick J. Kavanagh, Sarah Kendrew, David R. Law, Alberto Noriega-Crespo, Javier Álvarez-Márquez","doi":"10.1088/1538-3873/ad2551","DOIUrl":"https://doi.org/10.1088/1538-3873/ad2551","url":null,"abstract":"Astrometry is one of the main pillars of astronomy, and one of its oldest branches. Over the years, an increasing number of astrometric works by means of Hubble Space Telescope (HST) data have revolutionized our understanding of various phenomena. With the launch of JWST, it becomes almost instinctive to want to replicate or improve these results with data taken with the newest, state-of-the-art, space-based telescope. In this regard, the initial focus of the community has been on the Near-Infrared detectors on board of JWST because of their high spatial resolution. This paper begins the effort to capture and apply what has been learned from HST to the Mid-InfraRed Instrument (MIRI) of JWST by developing the tools to obtain high-precision astrometry and photometry with its imager. We describe in detail how to create accurate effective point-spread-function (ePSF) models and geometric-distortion corrections, analyze their temporal stability, and test their quality to the extent of what is currently possible with the available data in the JWST MAST archive. We show that careful data reduction provides deep insight on the performance and intricacies of the MIRI imager, and of JWST in general. In an effort to help the community devise new observing programs, we make our ePSF models and geometric-distortion corrections publicly available.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"40 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314907","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}
Pub Date : 2024-03-13DOI: 10.1088/1538-3873/ad2866
Pieter van Dokkum, Imad Pasha
Astronomical images often have regions with missing or unwanted information, such as bad pixels, bad columns, cosmic rays, masked objects, or residuals from imperfect model subtractions. In certain situations it can be essential, or preferable, to fill in these regions. Most existing methods use low order interpolations for this task. In this paper a method is described that uses the full information that is contained in the pixels just outside masked regions. These edge pixels are extrapolated inwards, using iterative median filtering. This leads to a smoothly varying spatial resolution within the filled-in regions, and ensures seamless transitions between masked pixels and good pixels. Gaps in continuous, narrow features can be reconstructed with high fidelity, even if they are large. The method is implemented in maskfill, an open-source MIT licensed Python package (https://github.com/dokkum/maskfill). Its performance is illustrated with several examples, and compared to several alternative interpolation schemes.
天文图像中经常会有信息缺失或不需要信息的区域，例如坏像素、坏柱、宇宙射线、遮挡物体或不完美的模型减法产生的残差。在某些情况下，对这些区域进行填充可能是必要的或可取的。现有的大多数方法都使用低阶插值来完成这项任务。本文介绍了一种利用遮挡区域外的像素所包含的全部信息的方法。使用迭代中值滤波法向内推断这些边缘像素。这使得填充区域内的空间分辨率变化平滑，并确保屏蔽像素和良好像素之间的无缝过渡。连续、狭窄特征中的间隙即使很大，也能高保真地重建。该方法在 MIT 授权的开源 Python 软件包 maskfill 中实现 (https://github.com/dokkum/maskfill)。我们用几个例子说明了该方法的性能，并将其与其他几种插值方案进行了比较。
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Pub Date : 2024-03-07DOI: 10.1088/1538-3873/ad1ed4
Alan W. McConnachie, Christian R. Hayes, J. Gordon Robertson, John Pazder, Michael Ireland, Greg Burley, Vladimir Churilov, Jordan Lothrop, Ross Zhelem, Venu Kalari, André Anthony, Gabriella Baker, Trystyn Berg, Edward L. Chapin, Timothy Chin, Adam Densmore, Ruben Diaz, Jennifer Dunn, Michael L. Edgar, Tony Farrell, Veronica Firpo, Javier Fuentes, Manuel Gomez-Jimenez, Tim Hardy, David Henderson, Alexis Hill, Kathleen Labrie, Jaclyn Jensen, Sam Lambert, Jon Lawrence, G. Scott Macdonald, Steven Margheim, Bryan Millar, Rolf Muller, Jon G. Nielsen, Gabriel Pérez, Carlos Quiroz, Roque Ruiz-Carmona, Kim M. Sebo, Federico Sestito, Kareleyne Silva, Chris Simpson, Greg Smith, Sudharshan Venkatesan, Fletcher Waller, Lewis Waller, Ivan Wevers, Kim A. Venn, Peter Young, Katherine Silversides
The Gemini High Resolution Optical Spectrograph (GHOST) is a fiber-fed spectrograph system on the Gemini South telescope that provides simultaneous wavelength coverage from 348 to 1061 nm, and is designed for optimal performance between 363 and 950 nm. It can observe up to two objects simultaneously in a 7.′5 diameter field of regard at R ≃ 56,000 or a single object at R ≃ 75,000. The spectral resolution modes are obtained by using integral field units to image slice a 1.″2 aperture by a factor of five in width using 19 fibers in the high resolution mode and by a factor of three in width using 7 fibers in the standard resolution mode. GHOST is equipped with hardware to allow for precision radial velocity measurements, expected to approach meters per second precision. Here, we describe the basic design and operational capabilities of GHOST, and proceed to derive and quantify the key aspects of its on-sky performance that are of most relevance to its science users.
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Pub Date : 2024-03-05DOI: 10.1088/1538-3873/ad220e
Nicholas Rackers, Sofia Splawska, Bharat Ratra
de Grijs & Bono compiled 211 independent measurements of the distance to galaxy M87 in the Virgo cluster from 15 different tracers and reported 31.03 ± 0.14 mag as the arithmetic mean of a subset of this compilation as the best estimate of the distance. We compute three different central estimates—the arithmetic mean, weighted mean, and the median—and corresponding statistical uncertainty for the full data set as well as three sub-compilations. We find that for all three central estimates the error distributions show that the data sets are significantly non-Gaussian. As a result, we conclude that the median is the most reliable of the three central estimates, as median statistics do not assume Gaussianity. We use median statistics to determine the systematic error on the distance by analyzing the scatter in the 15 tracer subgroup distances. From the 211 distance measurements, we recommend a summary M87 distance modulus of 31.08−0.04+0.05 (statistical) −0.06+0.04 (systematic) mag, or combining the two errors in quadrature 31.08−0.07+0.06 mag, rounded to 16.4 ± 0.5 Mpc, all at 68.27% significance.
{"title":"Median Statistics Estimate of the Distance to M87","authors":"Nicholas Rackers, Sofia Splawska, Bharat Ratra","doi":"10.1088/1538-3873/ad220e","DOIUrl":"https://doi.org/10.1088/1538-3873/ad220e","url":null,"abstract":"de Grijs & Bono compiled 211 independent measurements of the distance to galaxy M87 in the Virgo cluster from 15 different tracers and reported 31.03 ± 0.14 mag as the arithmetic mean of a subset of this compilation as the best estimate of the distance. We compute three different central estimates—the arithmetic mean, weighted mean, and the median—and corresponding statistical uncertainty for the full data set as well as three sub-compilations. We find that for all three central estimates the error distributions show that the data sets are significantly non-Gaussian. As a result, we conclude that the median is the most reliable of the three central estimates, as median statistics do not assume Gaussianity. We use median statistics to determine the systematic error on the distance by analyzing the scatter in the 15 tracer subgroup distances. From the 211 distance measurements, we recommend a summary M87 distance modulus of <inline-formula>\u0000<tex-math>\u0000<?CDATA ${31.08}_{-0.04}^{+0.05}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mn>31.08</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.04</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.05</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"paspad220eieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> (statistical) <inline-formula>\u0000<tex-math>\u0000<?CDATA ${}_{-0.06}^{+0.04}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.06</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.04</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"paspad220eieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> (systematic) mag, or combining the two errors in quadrature <inline-formula>\u0000<tex-math>\u0000<?CDATA ${31.08}_{-0.07}^{+0.06}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mn>31.08</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.07</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.06</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"paspad220eieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> mag, rounded to 16.4 ± 0.5 Mpc, all at 68.27% significance.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"53 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140317079","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}
Pub Date : 2024-02-29DOI: 10.1088/1538-3873/ad228e
Antonio C. Rodriguez, Yvette Cendes, Kareem El-Badry, Edo Berger
Astrometry from the Gaia mission was recently used to discover the two nearest known stellar-mass black holes (BHs), Gaia BH1 and Gaia BH2. These objects are among the first stellar-mass BHs not discovered via X-rays or gravitational waves. Both systems contain ∼1 M⊙ stars in wide orbits (a ≈ 1.4 au, 4.96 au) around ∼9 M⊙ BHs, with both stars (solar-type main sequence star, red giant) well within their Roche lobes in Gaia BH1 and BH2, respectively. However, the BHs are still expected to accrete stellar winds, leading to potentially detectable X-ray or radio emission. Here, we report observations of both systems with the Chandra X-ray Observatory, the Very Large Array (for Gaia BH1) and MeerKAT (for Gaia BH2). We did not detect either system, leading to X-ray upper limits of LX < 9.4 × 1028 and LX < 4.0 × 1029 erg s−1 and radio upper limits of Lr < 1.6 × 1025 and Lr < 1.0 × 1026 erg s−1 for Gaia BH1 and BH2, respectively. For Gaia BH2, the non-detection implies that the accretion rate near the horizon is much lower than the Bondi rate, consistent with recent models for hot accretion flows. We discuss implications of these non-detections for broader BH searches, concluding that it is unlikely that isolated BHs will be detected via interstellar medium accretion in the near future. We also calculate evolutionary models for the binaries’ future evolution using Modules for Experiments in Stellar Astrophysics, and find that Gaia BH1 will be visible as a symbiotic BH X-ray binary for 5–50 Myr. Since no symbiotic BH X-ray binaries are known, this implies either that fewer than ∼104 Gaia BH1-like binaries exist in the Milky Way, or that they are common but have evaded detection.
{"title":"No X-Rays or Radio from the Nearest Black Holes and Implications for Future Searches","authors":"Antonio C. Rodriguez, Yvette Cendes, Kareem El-Badry, Edo Berger","doi":"10.1088/1538-3873/ad228e","DOIUrl":"https://doi.org/10.1088/1538-3873/ad228e","url":null,"abstract":"Astrometry from the Gaia mission was recently used to discover the two nearest known stellar-mass black holes (BHs), Gaia BH1 and Gaia BH2. These objects are among the first stellar-mass BHs not discovered via X-rays or gravitational waves. Both systems contain ∼1 <italic toggle=\"yes\">M</italic>\u0000<sub>⊙</sub> stars in wide orbits (<italic toggle=\"yes\">a</italic> ≈ 1.4 au, 4.96 au) around ∼9 <italic toggle=\"yes\">M</italic>\u0000<sub>⊙</sub> BHs, with both stars (solar-type main sequence star, red giant) well within their Roche lobes in Gaia BH1 and BH2, respectively. However, the BHs are still expected to accrete stellar winds, leading to potentially detectable X-ray or radio emission. Here, we report observations of both systems with the Chandra X-ray Observatory, the Very Large Array (for Gaia BH1) and MeerKAT (for Gaia BH2). We did not detect either system, leading to X-ray upper limits of <italic toggle=\"yes\">L</italic>\u0000<sub>X</sub> < 9.4 × 10<sup>28</sup> and <italic toggle=\"yes\">L</italic>\u0000<sub>X</sub> < 4.0 × 10<sup>29</sup> erg s<sup>−1</sup> and radio upper limits of <italic toggle=\"yes\">L</italic>\u0000<sub>\u0000<italic toggle=\"yes\">r</italic>\u0000</sub> < 1.6 × 10<sup>25</sup> and <italic toggle=\"yes\">L</italic>\u0000<sub>\u0000<italic toggle=\"yes\">r</italic>\u0000</sub> < 1.0 × 10<sup>26</sup> erg s<sup>−1</sup> for Gaia BH1 and BH2, respectively. For Gaia BH2, the non-detection implies that the accretion rate near the horizon is much lower than the Bondi rate, consistent with recent models for hot accretion flows. We discuss implications of these non-detections for broader BH searches, concluding that it is unlikely that isolated BHs will be detected via interstellar medium accretion in the near future. We also calculate evolutionary models for the binaries’ future evolution using Modules for Experiments in Stellar Astrophysics, and find that Gaia BH1 will be visible as a symbiotic BH X-ray binary for 5–50 Myr. Since no symbiotic BH X-ray binaries are known, this implies either that fewer than ∼10<sup>4</sup> Gaia BH1-like binaries exist in the Milky Way, or that they are common but have evaded detection.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"44 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314615","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}
Pub Date : 2024-02-29DOI: 10.1088/1538-3873/ad1b37
Fengxian Tong, Weimin Zheng, Juan Zhang
Very long baseline interferometry (VLBI) plays a crucial role in geodesy and astrometry, and it is also being successfully used in spacecraft tracking. Phase referencing VLBI is a technique that uses phase information rather than the traditional VLBI group time delay to achieve higher measurement accuracy. The newly developed source-frequency phase referencing (SFPR) VLBI has been proven to be a powerful method to eliminate errors, but for positioning purposes, only “core shifts” are left in SFPR. Therefore, in this paper, an in-beam SFPR (IB-SFPR) VLBI method based on SFPR is proposed to overcome the positioning deficiency in SFPR, and to achieve high positioning accuracy. The proposed IB-SFPR method is further researched in more detail and shown to have the ability to achieve high positioning accuracy. For the first Martian rover of China, the IB-SFPR is first applied in its positioning. The positioning results of the rover have shown that the 1σ formal position error is hundreds of meters, with a formal error of post-fitted phase time delay of about 1.3 ps. However, the position discrepancies among the results of IB-SFPR, the guidance, navigation and control system, and the visual localization are at kilometer level, which are mainly affected by the orbit error of the orbiter. Therefore, considering the external reference’s (the obiter) orbit error, the final positioning accuracy of the Martian rover is at the kilometer level.
{"title":"An in-beam Source-frequency Phase Referencing VLBI Positioning Method for China’s First Martian Rover","authors":"Fengxian Tong, Weimin Zheng, Juan Zhang","doi":"10.1088/1538-3873/ad1b37","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1b37","url":null,"abstract":"Very long baseline interferometry (VLBI) plays a crucial role in geodesy and astrometry, and it is also being successfully used in spacecraft tracking. Phase referencing VLBI is a technique that uses phase information rather than the traditional VLBI group time delay to achieve higher measurement accuracy. The newly developed source-frequency phase referencing (SFPR) VLBI has been proven to be a powerful method to eliminate errors, but for positioning purposes, only “core shifts” are left in SFPR. Therefore, in this paper, an in-beam SFPR (IB-SFPR) VLBI method based on SFPR is proposed to overcome the positioning deficiency in SFPR, and to achieve high positioning accuracy. The proposed IB-SFPR method is further researched in more detail and shown to have the ability to achieve high positioning accuracy. For the first Martian rover of China, the IB-SFPR is first applied in its positioning. The positioning results of the rover have shown that the 1<italic toggle=\"yes\">σ</italic> formal position error is hundreds of meters, with a formal error of post-fitted phase time delay of about 1.3 ps. However, the position discrepancies among the results of IB-SFPR, the guidance, navigation and control system, and the visual localization are at kilometer level, which are mainly affected by the orbit error of the orbiter. Therefore, considering the external reference’s (the obiter) orbit error, the final positioning accuracy of the Martian rover is at the kilometer level.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"7 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316723","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}
Pub Date : 2024-02-22DOI: 10.1088/1538-3873/ad11a0
Patrick Miller, Robert Weryk, Richard Wainscoat, Jules Perret, Steve Hartung, Tomas Vorobjov, Luca Buzzi, Herbert Raab, Serge Chastel, John Fairlamb, Mark Huber, Yudish Ramanjooloo, Kenneth Chambers, Thomas de Boer, Hua Gao, Roger Chien-Cheng Lin, Eugene Magnier, Carlton Pennypacker
We describe a citizen science asteroid detection system developed by the International Astronomical Search Collaboration (IASC) and the Institute for Astronomy at the University of Hawaii, utilizing data from the Pan-STARRS telescopes. The goals of this project are to (i) educate and engage citizen scientists (mostly high school students) in science and astronomy, (ii) search for new asteroids to extend the limiting magnitudes of existing asteroid surveys, and (iii) find missed Near-Earth Objects (NEOs—objects with perihelia q < 1.3 au) to support planetary defense efforts. Over the past 15 yr, 50,000 citizen scientists from 96 countries around the world have detected ∼12,000 main-belt asteroids and ∼5 NEOs. Citizen scientists use the software Astrometrica during scheduled campaigns to search for and measure asteroid astrometry and photometry, and submit the data to IASC for vetting. Candidate detections not already submitted by Pan-STARRS are then submitted to the Minor Planet Center, and are typically ∼0.30 ± 0.07 mag fainter.
{"title":"The International Astronomical Search Collaboration (IASC)—Citizen Scientist System for Asteroid Discovery","authors":"Patrick Miller, Robert Weryk, Richard Wainscoat, Jules Perret, Steve Hartung, Tomas Vorobjov, Luca Buzzi, Herbert Raab, Serge Chastel, John Fairlamb, Mark Huber, Yudish Ramanjooloo, Kenneth Chambers, Thomas de Boer, Hua Gao, Roger Chien-Cheng Lin, Eugene Magnier, Carlton Pennypacker","doi":"10.1088/1538-3873/ad11a0","DOIUrl":"https://doi.org/10.1088/1538-3873/ad11a0","url":null,"abstract":"We describe a citizen science asteroid detection system developed by the International Astronomical Search Collaboration (IASC) and the Institute for Astronomy at the University of Hawaii, utilizing data from the Pan-STARRS telescopes. The goals of this project are to (i) educate and engage citizen scientists (mostly high school students) in science and astronomy, (ii) search for new asteroids to extend the limiting magnitudes of existing asteroid surveys, and (iii) find missed Near-Earth Objects (NEOs—objects with perihelia <italic toggle=\"yes\">q</italic> < 1.3 au) to support planetary defense efforts. Over the past 15 yr, 50,000 citizen scientists from 96 countries around the world have detected ∼12,000 main-belt asteroids and ∼5 NEOs. Citizen scientists use the software Astrometrica during scheduled campaigns to search for and measure asteroid astrometry and photometry, and submit the data to IASC for vetting. Candidate detections not already submitted by Pan-STARRS are then submitted to the Minor Planet Center, and are typically ∼0.30 ± 0.07 mag fainter.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"10 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009588","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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