BROADBAND STUDY WITH SUZAKU OF THE MAGNETAR CLASS

Journal Article · Wed Oct 20 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/722/2/L162· OSTI ID:21452739

Enoto, T; Nakazawa, K; Makishima, K ^[1]; Rea, N ^[2]; Hurley, K ^[3]; Shibata, S ^[4]

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1. Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
2. Institut de Ciencies de l'Espai (ICE-CSIC, IEEC), Campus UAB, Facultat de Ciencies, Torre C5-parell, 2a planta, 08193 Bellaterra (Barcelona) (Spain)
3. Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States)
4. Department of Physics, Yamagata University, Yamagata 990 (Japan)

Broadband (0.8-70 keV) spectra of the persistent X-ray emission from nine magnetars were obtained with Suzaku, including three objects in apparent outburst. The soft X-ray component was detected from all of them, with a typical blackbody temperature of kT {approx} 0.5 keV, while the hard-tail component, dominating above {approx}10 keV, was detected at {approx}1 mCrab intensity from seven of them. Therefore, the spectrum composed of a soft emission and a hard-tail component may be considered to be a common property of magnetars, both in their active and quiescent states. Wide-band spectral analyses revealed that the hard-tail component has a 1-60 keV flux, F {sub h}, comparable to or even higher than that carried by the 1-60 keV soft component, F {sub s}. The hardness ratio (HR) of these objects, defined as {xi} {identical_to} F {sub h}/F {sub s}, was found to be tightly anti-correlated with their characteristic age {tau}{sub c} as {xi} = (3.3 {+-} 0.3) x ({tau}{sub c}/1 kyr){sup -0.67{+-}0.04} with a correlation coefficient of -0.989, over the range from {xi} {approx} 10 to {xi} {approx} 0.1. Magnetars in outburst states were found to lie on the same correlation as relatively quiescent ones. This HR is also positively correlated with their surface magnetic fields with a correlation coefficient of 0.873. In addition, the hard-tail component becomes harder toward sources with older characteristic ages, with the photon index changing from {approx}1.7 to {approx}0.4.

• OSTI ID: 21452739
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 722; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BOSONS
COSMIC RADIATION
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
EMISSION
ENERGY RANGE
EVOLUTION
IONIZING RADIATIONS
KEV RANGE
MAGNETIC FIELDS
MASSLESS PARTICLES
NEUTRON STARS
PHOTONS
RADIATIONS
SOFT COMPONENT
SOFT X RADIATION
STAR EVOLUTION
STARS
X RADIATION