Parkes observations for project P1363 semester 2025APRS_14

We propose to monitor the bursts from the hyperactive repeating fast radio burst FRB 20240619D over six months using the Murriyang UWL receiver. The primary aim is to study the evolution of burst activity and polarization properties with frequency and time, and to discover any potential periodicity in the burst activity. These insights will enhance our understanding of the progenitor, emission physics, and the immediate magneto-ionic environment of FRB 20240619D, thereby informing the general FRB population. A total of 15 hours of observing between August and November 2024 resulted in over 1300 bursts detected using the UWL receiver. Some bursts exhibit complex spectro-temporal emission patterns. The burst rate, based on Murriyang and MeerKAT observations, indicates that the source was active until September 2nd, after which it became inactive. Given that two other repeating FRBs have exhibited periodic activity cycles, it is reasonable to expect that FRB 20240619D could become active again, making continued monitoring crucial. The UWL receiver's broad frequency coverage and sensitivity are essential for detecting many bursts and enabling simultaneous observations at different frequencies. This is important for understanding the burst activity evolution with time and frequency, spectral properties, and underlying emission mechanisms. The combination of sensitivity and wide bandwidth makes Murriyang the ideal telescope for monitoring this FRB. Results from these observations will be pivotal in understanding FRB 20240619D's place within the broader repeater population and its potential connection to broader FRB progenitor models.

本研究拟采用穆里扬（Murriyang）超宽频低接收机（Ultra-Wideband Low receiver, UWL receiver），对超活跃重复快速射电暴（Fast Radio Burst, FRB）20240619D开展为期六个月的持续监测。本研究的核心目标是探究暴源活动与偏振特性随频率与时间的演化规律，并发掘暴源活动中潜在的周期性特征。这些研究结果将加深我们对FRB 20240619D的前身天体、辐射物理机制以及邻近磁离子环境的认知，进而为理解整体快速射电暴族群提供理论支撑。2024年8月至11月间共计15小时的观测中，依托该超宽频低接收机共探测到超过1300次快速射电暴，其中部分暴源展现出复杂的谱时辐射形态。基于穆里扬与MeerKAT望远镜的观测数据得到的暴率显示，该源的活跃状态持续至9月2日，此后便进入沉寂阶段。鉴于另外两例重复快速射电暴已展现出周期性活动周期，我们有理由推测FRB 20240619D或再次进入活跃状态，因此持续监测该源具有重要意义。该超宽频低接收机的宽频覆盖范围与高灵敏度，不仅有助于探测到大量快速射电暴，还可实现不同频率下的同步观测，这对于探究暴源活动随时间与频率的演化规律、光谱特性以及潜在辐射机制至关重要。高灵敏度与宽带宽的双重优势，使穆里扬望远镜成为监测该快速射电暴的理想设备。本次观测的研究结果，将为明确FRB 20240619D在更大规模重复暴族群中的定位，以及其与通用快速射电暴前身天体模型的潜在关联提供关键依据。