Parkes observations for project P1196 semester 2023APRS_03

We request observing time at the Parkes telescope for observing three millisecond pulsars (MSPs): J1242-4712, J2101-4800, and J2144-5237. These MSPs were discovered with the GMRT. Spectra, profile evolution with frequency, and the radio polarisation properties of these MSPs are hitherto unexplored. Hence observations with the Parkes UWL receiver will be very valuable in that aspect. We propose radio polarisation study with the Parkes telescope over the large bandwidth of UWL receiver between 0.7 to 4 GHz, to complement our knowledge of spectra and profile evolution with the GMRT observations. Proposed main aims of this proposal are, (i) Investigation of profile evolution with frequency (ii) Investigation of polarisation angle sweep allowing to constrain the emission geometry. (iii) Investigation of spectra for these MSPs from 150 MHz to 4 GHz with Parkes and GMRT observations. (iv) Two of the MSPs, J1242-4712, J2101-4800, are spider MSP systems, in a compact orbit with a low mass companion. These systems are extreme southern sources and can be only observed for about 40% of their orbit with the GMRT. The proposed observations with the Parkes UWL will allow us to probe the orbital phase-dependent polarisation and spectral properties of these systems. (v) For J2144-5237, a wide pulse profile with multiple profile components is observed. We aim to investigate the steepness of the PA sweep changes as a function of observing frequency for a given profile component as reported from previous investigations. We request 32 hrs of observing time at the Parkes to perform this study.

我们申请使用帕克斯（Parkes）望远镜的观测时间，以观测三颗毫秒脉冲星（millisecond pulsars, MSPs）：J1242-4712、J2101-4800与J2144-5237。这些毫秒脉冲星是通过巨型米波射电望远镜（Giant Metrewave Radio Telescope, GMRT）发现的。迄今为止，这类源的射电频谱、随频率演化的脉冲轮廓以及射电偏振特性均尚未被系统研究。因此，利用帕克斯望远镜的UWL接收机开展相关观测在此领域极具科学价值。我们计划借助帕克斯望远镜的UWL接收机，在0.7至4 GHz的宽频带范围内开展射电偏振研究，以补充我们通过GMRT观测所获取的关于频谱与脉冲轮廓演化的认知。本申请的核心研究目标如下：(i) 研究脉冲轮廓随频率的演化规律；(ii) 探究偏振角（Polarisation Angle, PA）扫掠特性，以约束脉冲辐射的几何结构；(iii) 结合帕克斯望远镜与GMRT的观测数据，对这三颗毫秒脉冲星在150 MHz至4 GHz频段内的射电频谱开展研究；(iv) 其中J1242-4712与J2101-4800两颗毫秒脉冲星属于蜘蛛状毫秒脉冲星系统，它们与低质量伴星处于紧密轨道运行状态。这类源属于极南天区天体，利用GMRT仅能在约40%的轨道周期内完成观测。而本次申请的帕克斯UWL接收机观测，将使我们能够探究这类系统随轨道相位变化的偏振与频谱特性；(v) 针对J2144-5237，已有观测发现其拥有包含多个分量的宽脉冲轮廓，我们计划针对已报道的各脉冲分量，研究其偏振角扫掠陡度随观测频率的变化情况。为完成本项研究，我们申请在帕克斯望远镜获得32小时的观测时间。