Periodic Radio and X-ray Emission from an Accreting White Dwarf Binary
The University of Sydney（悉尼大学）；Australia Telescope National Facility, CSIRO（澳大利亚望远镜国家设施，CSIRO）；ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav)（引力波发现卓越研究中心（OzGrav））；University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校）；Curtin University（科廷大学）；University of North Carolina, Chapel Hill（北卡罗来纳大学教堂山分校）
Kovi Rose, Joshua Pritchard, Tara Murphy, L. N. Driessen, D. L. Kaplan, M. Caleb, Ziteng Wang, A. Zic, I. Andreoni, J. Carney, B. N. Barlow, D. Dobie, M. Gu, G.… 展开作者
Kovi Rose, Joshua Pritchard, Tara Murphy, L. N. Driessen, D. L. Kaplan, M. Caleb, Ziteng Wang, A. Zic, I. Andreoni, J. Carney, B. N. Barlow, D. Dobie, M. Gu, G. Heald, D. Huber, E. Lenc, J. K. Leung, W. Lu, R. Momose, M. G. Pedersen, Y. Qu, N. Rea, I. de Ruiter, K. Shaji, G. R. Sivakoff, A. J. M. Thomson, Y. L. Wang, G. J. Yang, F. Zahedy
Long period radio transients (LPTs) are coherent bursts of polarised radio emission that repeat periodically on timescales of minutes to hours. Little is known about the physical origins of these systems. Astronomers have proposed magnetars that rotate slowly and white dwarfs that rapidly orbit with a companion star as potential explanations. While several recent examples appear to support the latter hypothesis, the mechanism generating these bright radio pulses remains poorly understood. Here we report our discovery and classification of the LPT ASKAP J174508.9-505149 as an accreting white dwarf binary. This object has a ~1.3h spectroscopic orbital period and exhibits orbitally-modulated X-ray emission and radio bursts. These elliptically polarised radio bursts drift in emission frequency, potentially due to a longer beat period, and turn off for several hours at a time. Some long period radio transients have been associated with non-interacting white dwarf binaries. We have spectroscopically confirmed this system as an accreting cataclysmic variable, identified through characteristic optical emission lines and an ongoing X-ray outburst. Our results strengthen the link between at least some long period radio transients and white dwarf binaries.
Localised thermonuclear bursts from accreting magnetic white dwarfs
新星爆炸是由全球热核失控引发的表面层的吸积白矮星。据预测，在白矮星上也可能发生局部热核爆发，类似于在吸积中子星上观察到的I型X射线爆发。在过去的$\approx40$年里，人们在几个场合观测到了来自双星系统TV Columnoid的无法解释的快速爆发，在这个双星系统中，质量从低质量的伴星吸积到中等强度的磁化白矮星上。在这些爆发期间，光学/UV光度在不到一小时内增加了$>3$的倍数，并在$\approx10$小时内消失。在紫外线谱线中观察到了快速的外流，速度为$>3500$ km s $^{-1}$，与白矮星表面的逃逸速度相当。在这里，我们报告在电视柱观测到的光学爆发，以及在另外两个吸积系统，大熊座EI和ASASSN-19 bh。爆发的总能量为经典新星爆炸（“微新星”）的总能量$\approx~10^{-6}$，与I型X射线爆发非常相似。我们排除吸积或恒星磁重联事件作为其起源，并建议热核失控事件在磁约束吸积柱作为一个可行的解释。
A persistent bow shock in a diskless magnetised accreting white dwarf
Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（尼古拉·哥白尼天文学中心，波兰科学院）；Centre for Extragalactic Astronomy, Department of Physics, Durham University（杜伦大学物理系河外天文中心）；INAF-Osservatorio Astronomico di Capodimonte（意大利国家天体物理研究所卡波迪蒙特天文台）；School of Physics and Astronomy, University of Southampton（南安普顿大学物理与天文学院）；INAF-Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；University of Oxford, Department of Physics, Astrophysics（牛津大学物理系天体物理学）；Institute of Space Sciences (ICE, CSIC)（空间科学研究所（欧洲空间科学中心，西班牙高等科学研究委员会））；Institut d’Estudis Espacials de Catalunya (IEEC)（加泰罗尼亚太空研究研究所）；South African Astronomical Observatory（南非天文台）；Department of Astronomy, University of Cape Town（开普敦大学天文系）；Department of Physics, University of the Free State（自由州大学物理系）；Department of Physics, University of Warwick（华威大学物理系）；Department of Astrophysics/IMAPP, Radboud University（拉德堡德大学天体物理学/IMAPP系）
Magnetically Confined Mountains on Accreting White Dwarfs
Escola de Artes, Ciências e Humanidades, Universidade de São Paulo（圣保罗大学艺术、科学与人文学院）；Instituto de Física de São Carlos, Universidade de São Paulo（圣保罗大学圣卡洛斯物理研究所）
The Post-Merger Magnetized Evolution of White Dwarf Binaries: The Double-Degenerate Channel of Sub-Chandrasekhar Type Ia Supernovae and the Formation of Magnetized White Dwarfs
