XMM-Newton observations of PSR J0726-2612, a radio-loud XDINS
Abstract
We present the results of an XMM-Newton observation of the slowly rotating (P = 3.4 s), highly magnetized (B ≈ 3 × 1013 G) radio pulsar PSR J0726-2612. A previous X-ray observation with the Chandra satellite showed that some of the properties of PSR J0726-2612 are similar to those of the X-ray-dim isolated neutron stars (XDINSs), a small class of nearby slow pulsars characterized by purely thermal X-ray spectra and undetected in the radio band. We confirm the thermal nature of the X-ray emission of PSR J0726-2612, which can be fitted by the sum of two blackbodies with temperatures kT1=0.074+0.006-0.011 keV and kT2=0.14+0.004-0.002 keV and emitting radii R1=10.4+10.8-2.8 km and R2=0.5+0.9-0.3 km, respectively (assuming a distance of 1 kpc). A broad absorption line modeled with a Gaussian profile centered at 0.39+0.02-0.03 keV is required in the fit. The pulse profile of PSR J0726-2612 is characterized by two peaks with similar intensity separated by two unequal minima, a shape and pulsed fraction that cannot be reproduced without invoking magnetic beaming of the X-ray emission. The presence of a single radio pulse suggests that in PSR J0726-2612 the angles that the dipole axis and the line of sight make with the rotation axis, ξ and χ, respectively, are similar. This geometry differs from that of the two radio-silent XDINSs with double-peaked pulse profiles similar to that of PSR J0726-2612, for which ξ ∼ 90° and χ ∼ 45° have recently been estimated. These results strengthen the similarity between PSR J0726-2612 and the XDINSs and support the possibility that the lack of radio emission from the latter might simply be due to an unfavorable viewing geometry.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- July 2019
- DOI:
- 10.1051/0004-6361/201935485
- arXiv:
- arXiv:1906.01372
- Bibcode:
- 2019A&A...627A..69R
- Keywords:
-
- pulsars: general;
- pulsars: individual: PSR J0726-2612;
- stars: neutron;
- X-rays: stars;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication in A&