CHIME/FRB discovery of an active new repeating fast radio burst source FRB 20240209A
ATel #16670; Vishwangi Shah (McGill University) on behalf of the CHIME/FRB Collaboration
on 25 Jun 2024; 07:12 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Kaitlyn Shin (kshin@mit.edu)
Subjects: Radio, Transient, Fast Radio Burst
The CHIME/FRB Collaboration reports the discovery of a new, active repeating source of FRBs (FRB 20240209A). We have detected fifteen bursts from this repeater since its discovery on 2024-02-09 at 07:10:14 UTC. A recent high activity of the repeater has been observed with six bursts detected over three consecutive days between 2024-06-19 and 2024-06-21, prior to the CHIME/FRB detection system being offline for maintenance. This source is at a declination of ~86 degrees, where CHIME’s limited mean daily exposure (FWHM of the beams at 600 MHz) of ~40 mins indicates a burst rate as high as ~100 bursts per day above a ~1 Jy ms fluence threshold.
Burst Arrival Time Detection S/N
2024-02-09 07:10:14 15.99
2024-02-17 06:36:05 9.24
2024-03-01 02:39:49 9.55
2024-03-09 04:29:37 16.78
2024-06-08 10:23:09 9.00
2024-06-12 08:51:06 14.42
2024-06-12 21:33:20 10.89
2024-06-15 07:55:53 11.17
2024-06-16 22:52:19 13.70
2024-06-19 08:57:36 10.46
2024-06-19 09:03:37 10.73
2024-06-19 10:11:00 10.30
2024-06-20 08:55:51 8.47
2024-06-20 09:14:46 8.53
2024-06-21 21:00:56 9.02
The above approximate UTC burst times at 400 MHz (topocentric at CHIME near Penticton, Canada) are from the real-time detection system and subject to optimization following proper burst fitting.
Based on the voltage data of the brightest burst, we obtained a structure-maximizing dispersion measure (DM) of 176.57(3) pc cm^-3. The maximum NE2001/YMW16 Galactic disk DM contribution in the direction of the source is ~56/53 pc cm^-3. A 90% upper limit on redshift of the source is estimated to be z ~ 0.13 (Bhardwaj et al. 2021 ApJL, 919, L24).
The best-fit localization was performed on the CHIME voltage data of seven bursts, giving an inverse-variance weighted best position of RA (J2000): 289.9160 +- 0.0044 deg (19h19m39.84s +- 15.28s), Dec (J2000): 86.0623 +- 0.0046 deg (86d03m44.28s +- 16.56s), with errors quoted at 1-sigma uncertainty (Michilli et al. 2021 ApJ, 910, 147). Using the PATH formalism (Aggarwal et al. 2021 ApJ, 911, 95) and the combined best-fit localization, we identified the galaxy PSO J289.8503+86.0609 as the most probable (P(O|x) = 0.98) host galaxy for this repeater. PATH was run using default priors with P(U) = 0.2 on the relevant PanSTARRS1 field. The galaxy has RA (J2000): 289.8503 deg (19h19m24.07s), Dec (J2000): 86.0609 deg (86d03m39.24s), a photometric redshift of ~ 0.13 from PS1-STRM consistent with the 90% upper-limit on z, and an extinction-corrected r-band magnitude of 17.3 (AB).
A preliminary polarimetric analysis of the voltage data gives a Faraday rotation measure (|RM|) of 6.9 +- 0.5 rad/m^2 and 3.5 +- 0.5 rad/m^2 (there is a sign ambiguity because of cable delay effects; Mckinven et al. 2021 ApJ, 920, 138), and degree of linear polarization ~80% and ~50%, for bursts FRB 20240209A and FRB 20240612A, respectively. The other five bursts with voltage data are unpolarized, with an upper-limit of L/I < 40%.
We also obtained preliminary fluences (averaged over the entire 400-800 MHz CHIME observing band) ranging from 450 +- 46 Jy ms for burst FRB 20240209A to 2.5 +- 0.4 Jy ms for burst FRB 20240612B.
We encourage rapid follow-up, especially radio interferometric observations to further localize FRB 20240209A.
Dynamic spectrum of the brightest burst and PATH host galaxy association for FRB 20240209A
