Parkes observations for project P976 semester 2018APRS_02

Spider pulsars - black widows (BW) and redbacks (RB) - reside in incredibly tight orbits with low-mass stellar companions. The close proximity of the two orbiting bodies leads to heavy irradiation of the companion by the pulsar wind, causing material to be driven from its surface. This excess material is not gravitationally bound to the star, and the extent to which it reaches can only be constrained by observing the duration of eclipses of the radio pulsar emission that it causes. Little information about these systems is set in stone: the physical processes behind the eclipses, the dimensions, densities and magnetic properties of the eclipse medium, mass loss rates and subsequent evolution of the companions, are all unknown. Previous radio studies of a handful of spider systems have highlighted the importance of high-time resolution and large frequency coverage in constraining their properties. Measurement of the flux density, dispersion measure, rotation measure and depolarisation of the pulsars, as a function of the orbits, directly probes the eclipse process and properties of the medium causing it. All of these measurables are frequency dependent, thus with ultra-wideband observations we will have access to an unparalleled insight into spider pulsar systems. We plan to observe three eclipses for each of three BWs and two RBs in order to constrain variability between the two classes, multiple systems within each class, and the eclipses in an individual system. In addition, such observations will demonstrate and help to optimise the capabilities of the new UWL receiver.

蜘蛛脉冲星（Spider pulsars）——涵盖黑寡妇（Black Widows, BW）与红背（Redbacks, RB）两类——与低质量恒星伴星处于极紧凑的双星轨道系统中。两颗天体的轨道间距极近，使得脉冲星风（pulsar wind）对伴星产生强烈辐射照射，驱使伴星表面物质向外抛射。这类过剩物质并未被恒星的引力束缚，其可抵达的空间范围仅能通过观测其遮挡射电脉冲星辐射（radio pulsar emission）的掩食持续时长来约束。目前学界对这类双星系统的认知仍存在诸多不确定性：掩食现象背后的物理过程、掩食介质的尺度、密度与磁属性、物质抛射率以及伴星的后续演化等问题均尚未明确。此前针对少量蜘蛛脉冲星系统的射电研究已凸显出高时间分辨率（high-time resolution）与宽频率覆盖范围（large frequency coverage）对约束系统属性的重要性。通过测量脉冲星在不同轨道相位下的流量密度（flux density）、色散量（dispersion measure）、旋转量（rotation measure）与去偏振程度（depolarisation），可直接探究掩食过程与产生掩食的介质属性。上述所有可观测物理量均与频率相关，因此借助超宽带观测（ultra-wideband observations），我们将能够获得前所未有的深入认知以解析蜘蛛脉冲星系统。本研究计划对3颗黑寡妇与2颗红背脉冲星各开展3次掩食观测，以期约束两类系统间的特性差异、同类系统间的个体差异，以及单系统内的掩食特性。此外，此类观测还将验证并助力优化新型超宽带（UWL）接收机的性能。