| Abstract: FRB 20200120E is the nearest repeating Fast Radio Burst (FRB), residing in a globular cluster (GC). No persistent radio source has been detected around it. At 1.5 GHz, the observed FRB radio luminosity(Lr) upper limit on Log10(Lr(erg/s)) is 32.7. Besides, the observed limit on X-ray luminosity(Lx(1-10 keV)) is Log10(Lx) <37.1 erg/s. The location of this FRB challenges the traditional young magnetar-FRB association since GCs host old stellar populations. It is well known that GCs are abundant in accreting compact objects (COs), such as low-mass X-ray binaries (LMXRBs) containing white dwarfs (WDs) or neutron stars (NSs), or black holes (BHs). If FRB 20200120E originates from an LMXRB, our analysis constraints Log10(Lr(erg/s)) <29.7, for BH populations, for Lx(1-10 keV)<37.1 erg/s. Besides, if the LMXRB contains an NS, this upper limit would become 28.7. We found that for both BH populations and NSs, some LMXRBs have been detected above the radio and X-ray limits, e.g., for GX339-4, belonging to the BH population, only around 38% of time it was detected beyond a Log10(Lr) of 29.7 at 1.5 GHz. However, almost 30% of the time, this source was observed above the Lx limit. For another BH LMXRB, V404 Cyg, this statistics is around 61% and 30% for Lr and Lx respectively. Considering all the BH LMXRBs together so far, less than 32% of the simultaneous/quasi-simultaneous Lr and Lx crosses the FRB luminosity upper limits, whereas most of the time they are less bright than these limits, supporting LMXRBs as potential FRB progenitors. |
