CHIME/FRB Updated Position for Repeating Source FRB 20240316A
ATel #16780; Alice P. Curtin (McGill University) for the CHIME/FRB Collaboration
on 20 Aug 2024; 17:55 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Kaitlyn Shin (kshin@mit.edu)
Subjects: Radio, Fast Radio Burst
In Atel #16734, the CHIME/FRB Collaboration reported the discovery of a new, active repeating source, FRB 20240316A. Here, we report additional bursts from this source and provide an updated position using the CHIME/FRB raw voltage system (herein referred to as the 'baseband' system).
Below are all additional bursts detected by CHIME/FRB from this source since 2024-07-25 with S/N > 8. The burst arrival times (topocentric at CHIME near Penticton, Canada at 400 MHz) are from the real-time detection system and subject to optimization following proper burst fitting. No bursts from this source with S/N > 8 were detected with CHIME/FRB between 2024-08-05 and 2024-08-19. However, we detected a burst from this source on 2024-08-20, suggesting the source may be turning on again.
| TNS Name |
Time of Arrival (UTC) |
Signal-to-Noise Ratio |
| FRB 20240725A |
2024-07-25 11:23:55 |
13.3 |
| FRB 20240726A |
2024-07-26 11:11:22 |
9.1 |
| FRB 20240726B |
2024-07-26 11:16:40 |
9.9 |
| FRB 20240726C |
2024-07-26 11:18:14 |
18.5 |
| FRB 20240726D |
2024-07-26 11:20:43 |
10.0 |
| FRB 20240726E |
2024-07-26 11:21:32 |
9.6 |
| FRB 20240726G |
2024-07-26 11:21:37 |
16.8 |
| FRB 20240729A |
2024-07-29 11:08:40 |
11.7 |
| FRB 20240729B |
2024-07-29 11:12:47 |
19.7 |
| FRB 20240805A |
2024-08-05 10:40:00 |
17.5 |
| FRB 20240805B |
2024-08-05 10:39:05 |
12.5 |
| FRB 20240820A |
2024-08-20 09:39:08 |
9.0 |
Based on the baseband data of FRB 20240726C, we obtain a structure-maximizing dispersion measure of 351 +/- 1 pc cm-3. We determine an improved localization for the source using the baseband data from FRB 20240722B, FRB 20240724F, FRB 20240724L, FRB 20240726C, and FRB 20240805B. Our analysis gives an inverse-variance weighted best position of RA (J2000): 354.57 +/- 0.01 deg (23h38m16.8s), Dec (J2000): 32.33 +/- 0.01 deg (32d19m48s), with errors quoted at a 90% certainty level (Michilli et al. 2021 ApJ, 910, 147). We do not differentiate between systematic and random uncertainties when determining the inverse-variance weighted best position.
Using the PATH formalism (Aggarwal et al. 2021 ApJ, 911, 95), the combined best-fit localization, and archival data from the DECaLS survey, we found two possible hosts, but neither has P(O|x) > 0.8. An improved localization is required in order to identify the host galaxy of this source.
A preliminary polarimetric analysis of the voltage data gives an average Faraday rotation measure (RM) of ~160 rad/m^2 (Mckinven et al. 2021 ApJ, 920, 138). We also obtained preliminary fluences (averaged over the entire 400-800 MHz CHIME observing band) ranging from 4.6 +/- 0.6 Jy ms for FRB 20240805B to 27 +/- 3 Jy ms for FRB 20240726C.
We note that the majority of bursts from this source have been detected in the lower half of the CHIME/FRB bandwidth (e.g., 400 - 600 MHz) and follow-up at lower frequencies could be fruitful. Bursts show a range of morphology with some bursts having multiple components and signs of downward drifting.
