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Register a new userXMM-Newton observation of PSR B2224+65 and its jet
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Added by
Chung Yue Hui David
Publication date
2011
fields
Physics
and research's language is
English
Authors
C. Y. Hui
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We have investigated the pulsar PSR B2224+65 and its X-ray jet with XMM-Newton. Apart from the long X-ray jet which is almost perpendicular to the direction of proper motion, a putative extended feature at the pulsar position, which oriented in the opposite direction of the proper motion, is also suggested by this deep X-ray imaging. Non-detection of any coherent X-ray pulsation disfavors the magnetospheric origin of the X-rays observed from the position of PSR B2224+65 and hence suggest that the interpretation of pulsar wind nebula is more viable. We have also probed the origin of PSR B2224+65 and identified a runaway star, which possibly originated from the Cygnus OB9 association, as a candidate for the former binary companion of the neutron stars progenitor.
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PSR J0740$+$6620 has a gravitational mass of $2.08pm 0.07~M_odot$, which is the highest reliably determined mass of any neutron star. As a result, a measurement of its radius will provide unique insight into the properties of neutron star core matter at high densities. Here we report a radius measurement based on fits of rotating hot spot patterns to Neutron Star Interior Composition Explorer (NICER) and X-ray Multi-Mirror (XMM-Newton) X-ray observations. We find that the equatorial circumferential radius of PSR J0740$+$6620 is $13.7^{+2.6}_{-1.5}$ km (68%). We apply our measurement, combined with the previous NICER mass and radius measurement of PSR J0030$+$0451, the masses of two other $sim 2~M_odot$ pulsars, and the tidal deformability constraints from two gravitational wave events, to three different frameworks for equation of state modeling, and find consistent results at $sim 1.5-3$ times nuclear saturation density. For a given framework, when all measurements are included the radius of a $1.4~M_odot$ neutron star is known to $pm 4$% (68% credibility) and the radius of a $2.08~M_odot$ neutron star is known to $pm 5$%. The full radius range that spans the $pm 1sigma$ credible intervals of all the radius estimates in the three frameworks is $12.45pm 0.65$ km for a $1.4~M_odot$ neutron star and $12.35pm 0.75$ km for a $2.08~M_odot$ neutron star.
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