We report the study of the short ( 32 ms ) and first SGR-like burst observed from the anomalous X-ray pulsar ( AXP ) 1E 1841–045 associated with the supernova remnant ( SNR ) Kes 73 , discovered on 2010 May 6 by the Burst Alert Telescope ( BAT ) onboard the Swift \gamma -ray observatory .
The 15–100 keV time-averaged burst spectrum is modeled by a single power-law ( PL ) with a photon index \Gamma =3.2 ^ { +1.8 } _ { -1.0 } , and has a fluence of 1.1 ^ { +0.4 } _ { -0.6 } \times 10 ^ { -8 } ergs cm ^ { -2 } , luminosity of 2.9 ^ { +1.1 } _ { -1.6 } \times 10 ^ { 39 } ergs s ^ { -1 } , and energy of 7.2 ^ { +0.4 } _ { -0.6 } \times 10 ^ { 36 } ergs .
The prompt after-burst 0.5–10 keV quiescent spectrum obtained with the Swift X-ray Telescope ( XRT ) is best-fit by an absorbed PL model with \Gamma =2.6 \pm 0.2 and an unabsorbed flux of 9.1 ^ { +1.2 } _ { -1.4 } \times 10 ^ { -11 } ergs cm ^ { -2 } s ^ { -1 } .
To investigate the pre-burst 0.5–10 keV persistent emission , we analyzed the archival XMM-Newton observations and the spectra are well fitted by a two-component blackbody ( BB ) plus PL model with a temperature kT =0.45 \pm 0.03 keV , \Gamma =1.9 \pm 0.2 , and an unabsorbed flux of 4.3 ^ { +0.9 } _ { -1.2 } \times 10 ^ { -11 } ergs cm ^ { -2 } s ^ { -1 } .
Comparing the Swift -XRT spectrum with the XMM-Newton spectrum , spectral softening post-burst is evident with a 2.1 times increase in the unabsorbed flux .
We discuss the burst activity and the persistent emission properties of AXP 1E 1841–045 in comparison with other magnetars and in the context of the magnetar model .