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
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
Issn Identifier
0004-6361
Ads BibCode
2019A&A...627A..69R
Rights
open.access
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