Suzaku Discovery of a Hard X-Ray Tail in the Persistent Spectra from the Magnetar 1E 1547.0-5408 during its 2009 Activity
Abstract
The fastest-rotating magnetar 1E 1547.0-5408 was observed in broad-band X-rays with Suzaku for 33 ks on 2009 January 28-29, 7 d 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 × 10-1erg cm-2s-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 ∼110 keV, with an even higher flux of 1.3 × 10-10erg cm-2s-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 ∼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) × 1035erg s-1 and 1.9 × 1036erg s-1, respectively, while the blackbody radius becomes ∼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.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- April 2010
- DOI:
- 10.1093/pasj/62.2.475
- arXiv:
- arXiv:1002.3668
- Bibcode:
- 2010PASJ...62..475E
- Keywords:
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- stars: magnetic fields;
- X-rays: individual (1E 1547.0-5408);
- X-rays: stars;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 12 pages, 7 figures, PASJ Vol.62 No.2 accepted