Parkes observations for project P1129 semester 2021OCTS_02

PSR J0837-2454 is a young, high-Galactic-latitude pulsar, whose distance derived from dispersion measure (DM) implies a height of $>$1~kpc above the Galactic plane. The young age (28kyr) and position can be explained if (i) the pulsar was born at this high Galactic $z$-height from a runaway or walkaway O/B star; or (ii) the DM-derived distance to this pulsar is incorrect and the pulsar is closer to the plane of the Galaxy. Obtaining a coherent timing solution for the pulsar over the coming year will allow gated VLBA observations which, along with an independent estimate of the proper motion, will also provide us with a distance to the pulsar through a measurement of the parallax, if the pulsar is closer than the DM implies. These measurements are crucial to determining whether or not this pulsar represents the remnants of a rare Milky Way halo O/B star. In addition, studying the scattering and scintillation will allow us to test whether there is any additional source of DM along the line of sight to the pulsar that might inflate its DM-derived distance, and hence its height above the Galactic plane. Finally, measuring the polarisation properties of the pulsar will allow us to study its beam geometry, as well as further investigate the ISM and the Galactic magnetic field in this direction.

PSR J0837-2454是一颗年轻的高银纬（Galactic latitude）脉冲星，其由色散量（dispersion measure，DM）推导得出的距离表明，它位于银道面以上大于1千秒差距（kiloparsec，kpc）的高度。该脉冲星的年轻年龄（28千年）与位置可通过以下两种情形解释：（i）它诞生于这一高银道z向高度（Galactic z-height），源自一颗逃逸或远离的O/B型星；或（ii）其DM推导距离不准确，实际更靠近银道面。未来一年若能获得该脉冲星的相干计时解（coherent timing solution），将可开展门控甚长基线阵列（Very Long Baseline Array，VLBA）观测；若该脉冲星的实际距离比DM推导结果更近，则结合自行（proper motion）的独立估计，通过视差（parallax）测量也能为我们提供其距离。这些测量对于确定该脉冲星是否为罕见的银河系晕（Galactic halo）O/B型星遗迹至关重要。此外，研究散射和闪烁现象有助于验证脉冲星视线方向上是否存在额外的DM来源，这些来源可能高估其DM推导距离，进而高估其银道面以上的高度。最后，测量该脉冲星的偏振特性可帮助研究其辐射束几何结构，并进一步探究该方向上的星际介质（Interstellar Medium，ISM）与银磁场（Galactic magnetic field）。