A new X-ray look into four old pulsars

作者：Rigoselli Michela^*; Mereghetti Sandro

来源：Astronomy & Astrophysics, 2018, 615: A73.

DOI：10.1051/0004-6361/201732408

• pulsars: general
• stars: neutron
• pulsars: individual: PSR B0628-28
• pulsars: individual: PSR B0919+06
• pulsars: individual: PSR B0114+58
• pulsars: individual: PSR B1133+16

We report on the X-ray properties of four rotation-powered pulsars with characteristic ages in the range 0.3-5 Myr, derived from the analysis of XMM Newton archival observations. We found convincing evidence of thermal emission only in the phase-averaged spectrum of PSR B0114+58, which is well fitted by a blackbody with temperature kT = 0.17 +/- 0.02 keV and emitting radius R = 405(-90)(+110) m, consistent with the size of its polar cap. The three other considered pulsars, PSR B0628-28, PSR B0919+06, and PSR B1133+16, have phase-averaged spectra that can be described well by single power laws with photon index Gamma similar to 3. The 3 sigma upper limits on the bolometric luminosity of a possible thermal component with temperatures in the range similar to 0.05-2 keV are L-bol less than or similar to 3.2 x 10(28) erg s(-1) and L-bol less than or similar to 2.4 x 10(29) erg s(-1), for PSR B0628-28 and PSR B0919+06, respectively. On the other hand, we found possible evidence that the pulsed emission of PSR B0628-28 is thermal. Two absorption lines at similar to 0.22 keV and similar to 0.44 keV are detected in the spectrum of PSR B1133+16. They are best interpreted as proton cyclotron features, implying the presence of multipolar components with a field of a few 10(13) G at the neutron star polar caps. We discuss our results in the context of high-energy emission models of old rotation -powered pulsars.

• 出版日期2018-7-17