Repeating FRB 20240114A: the flaring radio source is linked to the FRB

ATel #17711; Xian Zhang (Guizhou University/Shanghai Astronomical Observatory), Wenfei Yu (Shanghai Astronomical Observatory)
on 6 Mar 2026; 12:32 UT
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Credential Certification: Wenfei Yu (wenfei@shao.ac.cn)

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After the discovery of the radio continuum counterpart associated with the repeating FRB 20240114A with MeerKAT (ATel #16695), various efforts on investigating its nature as a persistent radio source has been performed (for example, Bhusare et al. 2024; Bruni et al. 2025). With the detection of a flux doubling in the L-band with the Karl G. Jansky Very Large Array (VLA) in late July 2024, less than six months since its first MeerKAT observations soon after the FRB discovery, the size of the radio continuum counterpart, which we named as a Flaring Radio Source (FRS), is constrained to less than half parsec by light-crossing limit (Zhang et al. 2025), hardly accessible by current VLBI facilities. Here we follow up on the Karl G. Jansky Very Large Array (VLA) DDT multi-band observations (Project IDs: 24A-488 and 24B-467; PI: Xian Zhang) of the variable radio continuum counterpart in July 2024, October 2024 and February 2025, jointed with the monitoring of the burst properties by FAST (Zhou et al. 2026).

The FRB has been monitored by FAST since early 2024 and remained active until roughly the first half of 2025, providing an excellent opportunity to investigate potential physical connection between the burst engine and the FRS and understand the flaring nature. The most regular cadence of the FAST monitoring observations of FRB 20240114A is approximately once a week. We set a week-long time window to study the correlation between the FRS flux density and the burst rate of FRB in L-band. Within each window, we averaged the burst rate measurements and the FRS flux densities, respectively, which result in five FRS flux density -- burst rate data pairs. We found a strong correlation between the FRS flux density and the burst rate, with a Pearson correlation coefficient of 0.984 and y-axis (FRS flux density) intercept is 60.62+/-3.52 microJy. The intercept might suggest that the FRS contains two components. In the analysis, the visibility of the three VLA observations in February 2025 were stacked, followed by image detection to obtain an average flux density of 64+/-15 microJy. The strong correlation proves that the FRS is physically linked to the FRB, further demonstrates that the radio source was an FRS. These results are part of our revised version of Zhang et al. 2025.

We thank the staff at National Radio Astronomical Observatory for scheduling and performing the VLA DDT observations and the staff at South Africa Radio Astronomical Observatory for performing the MeerKAT observations and making the data available. We thank Dr. Zhou D. K. for sharing the plot data and the FAST FRB key science project for the monitoring observations.

References:

Zhou D. K. et al. 2026, Science China: Physics, Mechanics & Astronomy, Vol. 69, No. 4: 249512 (https://www.sciengine.com/SCPMA/doi/10.1007/s11433-025-2866-2)

Bhusare, Y., Maan, Y., & Kumar, A. 2025, ApJ, 993, 234

Bruni, G., Piro, L., Yang, Y. -P. et al. 2025, A&A, 695, L12

Zhang, X. Yu, W., Yan, Z. et al. 2025, arXiv:2501.14247 (https://arxiv.org/abs/2501.14247).