Parkes observations for project P1363 semester 2025APRS_07

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.

本研究拟利用穆里扬（Murriyang）超宽频（UWL）接收机，对超活跃重复快速射电暴（fast radio burst, FRB）20240619D的暴发现象开展为期六个月的监测。本项目的核心目标为：研究暴发现象活跃度与偏振特性随频率和时间的演化规律，探寻暴发现象中潜在的周期性特征。上述研究成果将加深我们对FRB 20240619D的前身天体、辐射物理及其紧邻磁离子环境的认知，进而为揭示快速射电暴的整体种群特征提供参考。2024年8月至11月期间，我们累计开展了15小时的观测，依托UWL接收机共探测到超过1300次快速射电暴。部分暴源呈现出复杂的谱时辐射形态。基于穆里扬与米尔卡特（MeerKAT）望远镜的观测数据得到的爆发率显示，该源的活跃状态持续至2024年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被观测到存在周期性活动周期，我们有理由推测FRB 20240619D有可能再次进入活跃状态，因此持续开展监测工作至关重要。UWL接收机具备的宽频覆盖范围与高灵敏度，不仅能够探测到大量暴源信号，还支持在不同频率下开展同步观测。这一特性对于解析暴发现象随时间与频率的演化规律、光谱特性以及潜在辐射机制均具有重要意义。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在重复暴种群中的定位，以及探索其与通用快速射电暴前身天体模型的潜在关联提供关键支撑。