A cumulative search for hard X/γ-ray emission associated with fast radio bursts in Fermi/GBM data

• Published in: Astronomy and astrophysics (Berlin) 2019-11, Vol.631, p.A62
• Main Authors: Martone, R., Guidorzi, C., Margutti, R., Nicastro, L., Amati, L., Frontera, F., Marongiu, M., Orlandini, M., Virgilli, E.
• Format: Article
• Language: English
• Subjects: Fluence; Gamma ray bursts; Gamma rays; gamma rays: general; gamma-ray burst: general; Machine learning; Magnetars; Radio bursts; radio continuum: general; Radio frequency
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/201936284

Context. Fast radio bursts (FRBs) are millisecond-long bursts uniquely detected at radio frequencies. FRB 131104 is the only case for which a γ-ray transient positionally and temporally consistent was claimed. This high-energy transient had a duration of ∼400 s and a 15–150 keV fluence Sγ ∼ 4 × 10−6 erg cm−2. However, the association with the FRB is still debated. Aims. We aim at testing the systematic presence of an associated transient high-energy counterpart throughout a sample of the FRB population. Methods. We used an approach like that used in machine learning methodologies to accurately model the highly-variable Fermi/GBM instrumental background on a time interval comparable to the duration of the proposed γ-ray counterpart of FRB 131104. A possible γ-ray signal is then constrained considering sample average lightcurves. Results. We constrain the fluence of the possible γ-ray signal in the 8–1000 keV band down to 6.4 × 10−7 (7.1 × 10−8) erg cm−2 for a 200-s (1-s) integration time. Furthermore, we found the radio-to-gamma fluence ratio to be η >  108 Jy ms erg−1 cm2. Conclusions. Our fluence limits exclude ∼94% of Fermi/GBM detected long gamma-ray bursts and ∼96% of Fermi/GBM detected short gamma-ray bursts. In addition, our limits on the radio-to-gamma fluence ratio point to a different emission mechanism from that of magnetar giant flares. Finally, we exclude a γ-ray counterpart as fluent as the one possibly associated with FRB 131104 to be a common feature of FRBs.