In January 2009 , the 2.1-sec anomalous X-ray pulsar 1E 1547.0 - 5408 evoked intense burst activity .
A follow-up Suzaku observation on January 28 recorded enhanced persistent emission both in soft and hard X-rays ( 16 ) .
Through re-analysis of the same Suzaku data , 18 short bursts were identified in the X-ray events recorded by the Hard X-ray Detector ( HXD ) and the X-ray Imaging Spectrometer ( XIS ) .
Their spectral peaks appear in the HXD-PIN band , and their 10–70 keV X-ray fluences range from \sim 2 \times 10 ^ { -9 } erg cm ^ { -2 } to 10 ^ { -7 } erg cm ^ { -2 } .
Thus , the 18 events define a significantly weaker burst sample than was ever obtained , \sim 10 ^ { -8 } – 10 ^ { -4 } erg cm ^ { -2 } .
In the \sim 0.8 to \sim 300 keV band , the spectra of the three brightest bursts can be represented successfully by a two-blackbody model , or a few alternative ones .
A spectrum constructed by stacking 13 weaker short bursts with fluences in the range ( 0.2–2 ) \times 10 ^ { -8 } erg s ^ { -1 } is less curved , and its ratio to the persistent emission spectrum becomes constant at \sim 170 above \sim 8 keV .
As a result , the two-blackbody model was able to reproduce the stacked weaker-burst spectrum only after adding a power-law model , of which the photon index is fixed at 1.54 as measured is the persistent spectrum .
These results imply a possibility that the spectrum composition employing an optically-thick component and a hard power-law component can describe wide-band spectra of both the persistent and weak-burst emissions , despite a difference of their fluxes by two orders of magnitude .
Based on the spectral similarity , a possible connection between the unresolved short bursts and the persistent emission is discussed .