Deep JWST/NIRCam Imaging of FRB 20250316A: Detection of Potential IR Counterparts
ATel #17195; Peter K. Blanchard, Edo Berger, Daichi Hiramatsu, Walter W. Golay, Harsh Kumar (Harvard/CfA), Brian Metzger (Columbia), Navin Sridhar (Stanford), Kohki Uno (Kyoto)
on 20 May 2025; 10:38 UT
Credential Certification: Peter Blanchard (pblanchard@cfa.harvard.edu)
Subjects: Infra-Red, Fast Radio Burst
We obtained deep imaging of the location of FRB 20250316A (ATels #17081, #17114) using NIRCam on the James Webb Space Telescope starting at 2025 May 19 at 13:55 UT. Observations were taken with the extra-wide F150W2 and F322W2 filters, with the science exposure time in each filter totaling 2.6 hours.
We detect two faint point-like sources in the F150W2 filter at the edge of the 1-sigma error ellipse of the CHIME/Outrigger position of FRB 20250316A (ATel #17114). The sources are not clearly detected in the F322W2 filter. We measure the following preliminary photometry for the brighter of the two sources: m_F150W2 = 30.12 +/- 0.17 mag. The second source is detected at roughly the level of the 5-sigma upper limit of m > 30.25 mag.
One of these sources may be an IR counterpart of FRB 20250316A, though given their location of ~0.12 arcsec from the nominal FRB position, it is also possible that a counterpart has not been detected. At the distance of the host galaxy NGC 4141, the F150W2 upper limit corresponds to an approximate absolute magnitude upper limit of m > -2.75 mag.
Analysis of the field is ongoing. We are working with the CHIME team to refine and improve the FRB position to match the JWST resolution.
