2019MNRAS.489.2685Y

The statistical properties of X-ray flares from two separate locations (nucleus and HST-1) in the M87 jet are investigated to reveal the physical origin of the flares. We analyse the archival Chandra data for M87, and identify 14 flares in the nucleus and nine flares in HST-1. The peak intensity (I_P) and the flaring duration time (T_fl) for each flare are obtained. It is found that the distributions of both I_P and T_fl for the nucleus obey a power law form with a similar index. A similar result is also obtained for HST-1, and no significant inconsistency between the nucleus and HST-1 is found for the indices. Similar to solar X-ray flares, the power-law distributions of the flare event parameters can be well explained by a self-organized criticality system, which are triggered by magnetic reconnection. Our results suggest that the flares from nucleus and HST-1 are possibly triggered by magnetic reconnection process. The consistent indices for the distributions of I_P and T_fl in the nucleus and HST-1 indicate that the dimensions of the energy dissipation of the magnetic reconnection are identical in the two regions. A strong correlation between the flares in the two regions also suggests a similar physical origin for the flares.