发表机构
Istituto Nazionale di Astrofisica (INAF) - Istituto di Radioastronomia (IRA); Department of Physics and Electronics, Rhodes University; South African Radio Astronomy Observatory; School of Physics and Astronomy, University of Minnesota; Department of Physics and Columbia Astrophysics Laboratory, Columbia University; Center for Computational Astrophysics, Flatiron Institute; Istituto Nazionale di Astrofisica (INAF) - Osservatorio di Astrofisica e Scienza dello Spazio (OAS) di Bologna; Istituto Nazionale di Astrofisica (INAF) - Osservatorio Astronomico di Cagliari; Dipartimento di Fisica e Astronomia (DIFA), Università di Bologna（意大利国家天体物理研究所-射电天文研究所; 罗德斯大学物理与电子系; 南非射电天文观测站; 明尼苏达大学物理与天文学学院; 哥伦比亚大学物理系与哥伦比亚天体物理实验室; 平托研究所计算天体物理学中心; 意大利国家天体物理研究所-博洛尼亚天体物理与空间科学观测站; 意大利国家天体物理研究所-卡利亚里天文台; 博洛尼亚大学物理与天文学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过VLBI观测确认了与重复FRB 20181030A相关的微弱持续射电源候选体20181030A-S1，其尺寸小于0.5秒差距，光度比已知PRS低约三个数量级，支持磁星动力星云起源。
AI 中文摘要
持续射电源（PRSs）是快速射电暴（FRBs）的连续谱对应体，后者是持续时间毫秒级、通量密度达央斯基级别的河外瞬变源。FRB-PRS系统被认为是由一个耀发的磁星被高磁化、富含重子的星云包围而成。我们旨在约束20181030A-S1的尺寸，这是一个新的PRS候选体，可能与重复暴FRB 20181030A相关。后者被定位于NGC 3252外围，不确定度约1角分，NGC 3252是一个距离为20兆秒差距的旋涡星系。我们报告了使用欧洲VLBI网络在1.7 GHz频率、角分辨率20毫角秒对这颗PRS候选体进行的甚长基线干涉测量（VLBI）观测。我们的观测揭示了在PRS候选体位置存在一个未分辨的射电源（20181030A-S1），证实了其在毫角秒尺度上的致密性。对点源位置的拟合得出峰值通量密度为280±30微央斯基，横向物理尺寸被约束为R<0.5秒差距（68%置信水平）。该通量密度转换为谱光度为(9±1)×10^25 erg s^-1 Hz^-1，比已确认的PRS低约3个数量级，使得20181030A-S1成为已知最近且最暗的PRS候选体。其低光度和适中的旋转测量与已确认FRB-PRS系统遵循的L_ν-旋转测量（RM）关系一致，支持磁星动力星云具有共同物理起源。我们展示了由初始磁场较弱（B_⋆≃10^15 G）且年轻（t_age≃15-150年）的磁星驱动的磁化风星云如何同时解释该系统的观测谱光度和RM。同时讨论了在20181030A-S1与FRB源无关的情况下其他可能的起源场景。
英文摘要
Persistent radio sources (PRSs) are the continuum counterparts of fast radio bursts (FRBs), the latter being extragalactic transients of millisecond duration and Jy-level flux density. An FRB-PRS system is thought to be a flaring magnetar surrounded by an highly magnetized, baryon-loaded nebula. We aim to constrain the size of 20181030A-S1, a new PRS candidate, potentially associated with the repeating FRB 20181030A. The latter is localized with $\sim 1'$ uncertainties in the outskirts of NGC 3252, which is a spiral galaxy at a luminosity distance of $20$ Mpc. We report very long baseline interferometric (VLBI) observations using the European VLBI Network at $1.7$ GHz of this PRS candidate at an angular resolution of $20$ milliarcseconds. Our observations reveal the presence of an unresolved radio source (20181030A-S1) at the position of the PRS candidate, confirming its compactness at milli-arcsecond angular scales. A fit to the position of the point-source yields a peak flux density of $280 \pm 30$ $μ$Jy and a transverse physical size constrained to be $R < 0.5$ pc at $68\%$ confidence level (CL). This flux density converts to a spectral luminosity of $(9 \pm 1) \times 10^{25}$ erg s$^{-1}$ Hz$^{-1}$, $\sim 3$ orders of magnitude lower than confirmed PRSs, making 20181030A-S1 the closest and faintest PRS candidate known. Its low luminosity and modest rotation measure are consistent with the $L_ν-$rotation measure (RM) relation followed by confirmed FRB--PRS systems, supporting a common physical origin in magnetar-powered nebulae. We show how a magnetized wind nebula powered by an initially weak ($B_\star \simeq 10^{15}$ G) and young ($t_{\rm age} \simeq 15 - 150$ yrs) magnetar can account for both the observed spectral luminosity and RM of the system. Other possible origin scenarios for 20181030A-S1, in the case in which it is unrelated to the FRB source, are also discussed.
Comments10 pages, 5 figures, submitted to A&A
