Parkes observations for project P1356 semester 2025APRS_16

Magnetars are neutron stars with exceptionally high magnetic fields. From the 30 known magnetars, only six have had radio emission detected so far. The remaining 24 magnetars are generally only searched for radio emission after an X-ray outburst. This added a strong selection bias to whether magnetars are radio loud or not. From the known six radio loud magnetars, we know that the radio emission changes quickly with time and for the magnetar XTE J1810-197, it has been observed that the radio flux increases strongly without an enhancement in X-ray flux. Thus, it remains unclear whether the radio quiet magnetars are in fact radio quiet and the radio X-ray relation appears to be rather complex.\n In this proposal, we propose a regular monitoring campaign of 4 radio quiet magnetars with bi-weekly observations using the Parkes UWL receiver. For 3 of the sources, we will have accompanying X-ray observations and thus, this will give an unique data set to probe the relation between radio and X-ray independent outbursts. Any detection of radio emission, i.e. single pulses or folded profiles, would be a major discovery and help to constrain the emission mechanisms of magnetars. This will also help to improve the understanding of the emission mechanism of fast radio bursts. However, also a non-detection of radio emission will provide upper limits that serve as a baseline before any future outburst of the observed magnetars as well as allow to constrain the formation process of magnetars in contrast to pulsars.

磁星（magnetar）是拥有极强磁场的中子星。截至目前，在已发现的30颗磁星中，仅6颗被探测到射电辐射。剩余24颗磁星通常仅在发生X射线爆发后才会被开展射电辐射搜寻，这为判断磁星是否属于射电亮源引入了显著的选择偏差。在已发现的6颗射电亮磁星中，我们已知其射电辐射会随时间快速变化；针对磁星XTE J1810-197的观测还显示，其射电流量出现显著提升，但X射线流量并未同步增强。因此，目前仍不清楚射电宁静磁星是否确实不产生射电辐射，且射电与X射线辐射的关联机制似乎相当复杂。
在本研究提案中，我们提议利用帕克斯UWL接收机（Parkes UWL receiver），以每两周一次的观测频次对4颗射电宁静磁星开展常规监测计划。其中3颗源将同步开展配套X射线观测，这将为我们提供一套独特的数据集，用于探究射电与X射线辐射在非爆发状态下的关联关系。若能探测到射电辐射（包括单脉冲或折叠轮廓），将是一项重大发现，有助于限定磁星的辐射机制，同时也能增进我们对快速射电暴（fast radio bursts）辐射机制的理解。反之，若未探测到射电辐射，也将为这些磁星提供射电辐射的上限值，既可作为该类天体未来爆发前的参考基线，也能帮助限定磁星相较于脉冲星的形成过程。