The Swift X-ray Observations Campaign of the Repeating FRB20220912A

ATel #16221; F. Verrecchia, M. Perri (INAF/OAR & ASI/SSDC), M. Tavani (INAF/IAPS & Univ. Roma Tor Vergata), C. Casentini (INAF/IAPS), M. Pilia (INAF/OA-Cagliari), C. Pittori (INAF/OAR & ASI/SSDC), D. Pelliciari (Univ. of Bologna, INAF/IRA), G. Bernardi, G. Bianchi, G. Naldi, G. Pupillo (INAF/IRA), on behalf of a large Collaboration
on 1 Sep 2023; 15:53 UT
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Credential Certification: Francesco Verrecchia (francesco.verrecchia@ssdc.asi.it)

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The report of the observations campaign with Swift XRT and UVOT instruments of the repeating Fast Radio Burst source FRB20220912A (J2000 R.A., Dec.= 347.2704, 48.7071 deg) during a time interval when the source was reported to be in a radio activity phase, with some possible bursting radio pulse actvity expected as reported by the NC radio telescope (ATel #16130).

Our Swift X-ray observations are part of a coordinated multiwavelength campaign of this FRB including AGILE gamma-ray observations and simultaneous radio observations by the Northern Cross radio telescope telescope (408 MHz) in Medicina.

We observed the location of FRB20220912A daily from Jul. 25th, 2023 to Jul. 30th in the following time intervals Jul 25th, within 00:09 - 02:14 UT, for 1520 s of effective exposure;
Jul 26th, within 00:05 - 02:02 UT, for 1280 s of effective exposure;
Jul 27th, within 01:22 - 03:20 UT, for 1677 s of effective exposure;
Jul 28th, within 01:08 - 01:36 UT, for 1709 s of effective exposure;
Jul 29th, within 00:55 - 02:39 UT, for 1705 s of effective exposure;
Jul 30th, within 02:23 - 02:48 UT, for 1491 s of effective exposure;

We obtained XRT data in Windowed Timing (WT) mode: a preliminary analysis indicates that no uncatalogued X-ray source compatible with the FRB position was detected in both observations. For the Galactic HI column density value in the source direction (n_H = 1.45 x 10^21 cm^-2, Kalberla et al. 2005, A&A, 440, 775) and assuming a single power-law spectrum of photon index 2, we obtain the following 3-sigma upper limits (ULs) in the range 0.3-10 keV:

1.62 x 10^-2 counts/s (flux UL: 5.8 x 10^-13 erg/cm^2/s) for the first observation on Jul. 25th;
1.69 x 10^-2 counts/s (flux UL: 6.1 x 10^-13 erg/cm^2/s) for the second set of observations on Jul. 26th;
1.06 x 10^-2 counts/s (flux UL: 3.8 x 10^-13 erg/cm^2/s) for the second set of observations on Jul. 27th;
1.83 x 10^-2 counts/s (flux UL: 6.6 x 10^-13 erg/cm^2/s) for the second set of observations on Jul. 28th;
1.80 x 10^-2 counts/s (flux UL: 6.5 x 10^-13 erg/cm^2/s) for the second set of observations on Jul. 29th;
1.97 x 10^-2 counts/s (flux UL: 7.1 x 10^-13 erg/cm^2/s) for the second set of observations on Jul. 30th.

Additional analysis of UVOT data is in progress. Further observations with Swift are on-going.

We encourage multifrequency observations of FRB20220912A. The Swift mission is part of NASA's medium explorer (MIDEX) program, led by NASA with participation of Italy and the UK. We thank the Swift Team for making these observations possible, in particular B. Cenko and K. L. Page (Swift Observatory Duty Scientist).