XMM-Newton observations of PSR J0726-2612, a radio-loud XDINS

Journal
Date Issued
2019
Author(s)
•
•
Valery Suleimanov
•
Alexander Y. Potekhin
•
Roberto Turolla
•
Roberto Taverna
•
Fabio Pintore
DOI
Abstract
We present the results of an XMM-Newton observation of the slowly rotating ($P = 3.4$ s), highly magnetized ($B \approx 3 \times 10^{13}$ 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 fit by the sum of two blackbodies with temperatures $kT_1 = 0.074_{-0.011}^{+0.006}$ keV and $kT_2 = 0.14_{-0.02}^{+0.04}$ keV and emitting radii $R_1 = 10.4_{-2.8}^{+10.8}$ km and $R_2 = 0.5_{-0.3}^{+0.9}$ km, respectively (assuming a distance of 1 kpc). A broad absorption line modeled with a Gaussian profile centred at $0.39_{-0.03}^{+0.02}$ 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, $\xi$ and $\chi$ respectively, are similar. This geometry differs from that of the two radio-silent XDINSs with a double peaked pulse profile similar to that of PSR J0726-2612, for which $\xi \sim 90^\circ$ and $\chi \sim 45^\circ$ have been recently 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 unfavourable viewing geometry.
Volume
627
Start page
A69
Uri
Url
Issn Identifier
0004-6361
Ads BibCode
2019A&A...627A..69R
Rights
open.access
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