DISCOVERY OF A STRONGLY PHASE-VARIABLE SPECTRAL FEATURE IN THE ISOLATED NEUTRON STAR RX J0720.4-3125

被引：31

作者：

Borghese, A. ^{[1
]}

Rea, N. ^{[1
,2
]}

Coti Zelati, F. ^{[1
,3
,4
]}

Tiengo, A. ^{[5
,6
,7
]}

Turolla, R. ^{[8
,9
]}

机构：

[1] Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1090 GE Amsterdam, Netherlands

[2] CSIC, IEEC, Inst Space Sci, E-08193 Barcelona, Spain

[3] Univ Insubria, I-22100 Como, Italy

[4] INAF, Osservatorio Astron Brera, I-23807 Merate, LC, Italy

[5] INAF, Ist Astrofis Spaziale & Fis Cosm, I-20133 Milan, Italy

[6] Ist Univ Super, I-27100 Pavia, Italy

[7] Ist Nazl Fis Nucl, Sez Pavia, I-27100 Pavia, Italy

[8] Univ Padua, Dipartimento Fis & Astron, I-35131 Padua, Italy

[9] Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England

来源：

ASTROPHYSICAL JOURNAL LETTERS | 2015年 / 807卷 / 01期

关键词：

stars: individual (RX J0720.4-3125); stars: neutron; X-rays: stars; MAGNETIC-FIELD; ABSORPTION; EVOLUTION;

D O I：

10.1088/2041-8205/807/1/L20

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present the discovery of a strongly phase-variable absorption feature in the X-ray spectrum of the nearby, thermally emitting, isolated neutron star RX J0720.4-3125. The absorption line was detected performing detailed phase-resolved spectroscopy in 20 XMM-Newton observations, covering the period 2000 May-2012 September. The feature has an energy of similar to 750 eV, an equivalent width of similar to 30 eV, and it is significantly detected for only similar to 20% of the pulsar rotation. The absorption feature appears to be stable over the timespan covered by the observations. Given its strong dependence on the pulsar rotational phase and its narrow width, a plausible interpretation is in terms of resonant proton cyclotron absorption/scattering in a confined magnetic structure very close to the neutron star surface. The inferred field in such a magnetic loop is B-loop similar to 2 x10 (14) G, a factor of similar to 7 higher than the surface dipolar magnetic field.

引用

页数：5

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