Suzaku Discovery of a Hard X-Ray Tail in the Persistent Spectra from the Magnetar 1E 1547.0-5408 during its 2009 Activity

The fastest-rotating magnetar IE 1547.0-5408 was observed in broad-band X-rays with Suzaku for 33 ks on 2009 January 28-29, 7d after the onset of its latest bursting activity. After removing burst events, the absorption-uncorrected 2-10 keV flux of the persistent emission was measured with the XIS as 5.7 x 10(-11)erg cm(-2) s(-1), which is 1-2 orders of magnitude higher than was measured in 2006 and 2007 when the source was less active. This persistent emission was also detected significantly with the HXD in > 10 keV up to at least similar to 110 keV, with an even higher flux of 1.3 x 10(-10) erg cm(-2) s(-1) in 20-100 keV. The pulsation was detected at least up to 70 keV for a period of 2.072135 +/- 0.00005 s, with a deeper modulation than was measured in a fainter state. The phase-averaged 0.7-114 keV spectrum was reproduced by an absorbed blackbody emission with a temperature of 0.65 +/- 0.02 keV, plus a hard power-law with a photon index of similar to 1.5. At a distance of 9 kpc, the bolometric luminosity of the blackbody and the 2-100 keV luminosity of the hard power-law are estimated to be (6.2 +/- 1.2) x 10(35) erg s(-1) and 1.9 x 10(36) erg s(-1), respectively, while the blackbody radius becomes similar to 5 km. Although the source has not been detected significantly in hard X-rays during the past fainter states, a comparison of the present and past spectra at energies below 10 keV suggests that the hard component is more enhanced than the soft X-ray component during the period of persistent activity.