THE X-RAY COUNTERPART OF THE HIGH-<i>B</i>PULSAR PSR J0726–2612

Speagle, Joshua S.; Kaplan, D. L.; Kerkwijk, M. H. van

doi:10.1088/0004-637x/743/2/183

Cited by 18 publications

(16 citation statements)

References 56 publications

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“…Its timing parameters (Table 1) are in the range of those of the XDINSs. The similarity with the XDINSs was reinforced by X-ray observations with the Chandra satellite (Speagle et al 2011), that revealed a soft thermal spectrum with blackbody temperature kT ≈ 87 eV, and pulsations with a sinusoidal, double-peaked profile. The distance of PSR J0726−2612 is unknown.…”

Section: Introductionmentioning

confidence: 56%

“…Pulse profile of PSR J0726−2612 in the energy range 0.15−1.5 keV obtained by folding the EPIC-pn data in 20 phase bins at the period derived from the radio ephemeris (Table 1). The vertical red line represents the location of the radio pulse (derived from Speagle et al 2011), with its uncertainty (1σ). The colored bands indicate the intervals used for the phase-resolved spectroscopy.…”

Section: Timing Analysismentioning

confidence: 99%

“…This local structure (d ∼ 200 − 400 pc) comprises several OB associations that have been proposed as the birthplace of the XDINSs (Popov et al 2003(Popov et al , 2005. Speagle et al (2011) suggested that also PSR J0726−2612 could be associated with the Gould belt and hence closer than ∼ 1 kpc.…”

Section: Introductionmentioning

confidence: 99%

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

Rigoselli

Mereghetti

Suleimanov

et al. 2019

A&A

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We present the results of an XMM-Newton observation of the slowly rotating (P = 3.4 s), highly magnetized (B ≈ 3×10 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 +0.006 −0.011 keV and kT 2 = 0.14 +0.04 −0.02 keV and emitting radii R 1 = 10.4 +10.8 −2.8 km and R 2 = 0.5 +0.9 −0.3 km, respectively (assuming a distance of 1 kpc). A broad absorption line modeled with a Gaussian profile centred 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 a double peaked pulse profile similar to that of PSR J0726−2612, for which ξ ∼ 90 • and χ ∼ 45 • 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.

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Section: Introductionmentioning

confidence: 56%

Section: Timing Analysismentioning

confidence: 99%

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

Rigoselli

Mereghetti

Suleimanov

et al. 2019

A&A

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“…Further analysis of light curves in different energy bands and phase resolved spectroscopic study (Schwope et al 2007;Hambaryan et al 2011) provided additional confirmation on a plausibility of the model of RBS 1223 with emergent emission dominated by two emitting areas with slightly different parameters. Yet another case, Speagle et al (2011) noted that without the radio period, they might have actually identified the pulse period of PSR J0726 as half of the true value. Cropper et al (2001) performed spin pulse profile analysis of RX J0720.4−3125 based on earlier XMM-Newton observations, also folded photon arrival times with twice of the detected period via Fourier periodogram which produced a double-humped light curve with different count rates at the different peak; however, having no indication of subharmonics in the periodogram, they did not really consider twice of the period as a true one.…”

Section: Fittedmentioning

confidence: 99%

The compactness of the isolated neutron star RX J0720.4−3125

Hambaryan

Suleimanov

Haberl

et al. 2017

A&A

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Aims. To estimate the compactness of the thermally emitting isolated neutron star RX J0720.4−3125, an X-ray spin phase-resolved spectroscopic study is conducted. In addition, to identify the genuine spin-period, an X-ray timing analysis is performed. Methods. The data from all observations of RX J0720.4−3125 conducted by XMM-Newton EPIC-pn with the same instrumental setup in 2000-2012 were reprocessed to form a homogenous data set of solar barycenter corrected photon arrival times registered from RX J0720.4−3125. A Bayesian method for the search, detection, and estimation of the parameters of an unknown-shaped periodic signal was employed as developed by Gregory & Loredo (1992). A number of complex models (single and double peaked) of light curves from pulsating neutron stars were statistically analyzed. The distribution of phases for the registered photons was calculated by folding the arrival times with the derived spin-period and the resulting distribution of phases -approximated with a mixed von Mises distribution -, and its parameters were estimated by using the Expected Maximization method. Spin phase-resolved spectra were extracted, and a number of highly magnetized atmosphere models of an INS were used to fit simultaneously, the results were verified via an MCMC approach. Results. The phase-folded light curves in different energy bands with high S/N ratio show a high complexity and variations depending on time and energy. They can be parameterized with a mixed von Mises distribution, i.e. with double-peaked light curve profile showing a dependence of the estimated parameters (mean directions, concentrations, and proportion) upon the energy band, indicating that radiation emerges from at least two emitting areas. Conclusions. The genuine spin-period of the isolated neutron star RX J0720−3125 derived as more likely is twice of that reported in the literature (16.78s instead of 8.39s). The gravitational redshift of RX J0720.4−3125 was determined to z = 0.205 +0.006 −0.003 and the compactness was estimated to (M/M )/(R/km) = 0.105 ± 0.002.

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“…In spite of many searches and interesting case studies, no other thermally emitting INS, presenting exactly the same characteristics as the M7, has been identified outside the solar vicinity to date (see also the case of the high-B radio pulsar PSR J0726-2612, which is another likely product of the Gould Belt; Speagle et al 2011). It is therefore very important for population studies to understand why there are so many thermally emitting sources with similar periods (and presumably ages and magnetic fields) in such a small volume.…”

Section: Future Prospectsmentioning

confidence: 99%

The peculiar isolated neutron star in the Carina Nebula

Pires

Motch

Turolla

et al. 2012

A&A

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While fewer in number than the dominant rotation-powered radio pulsar population, peculiar classes of isolated neutron stars (INSs) -which include magnetars, the ROSAT-discovered "Magnificent Seven" (M7), rotating radio transients (RRATs), and central compact objects in supernova remnants (CCOs) -represent a key element in understanding the neutron star phenomenology. We report the results of an observational campaign to study the properties of the source 2XMM J104608.7-594306, a newly discovered thermally emitting INS. The evolutionary state of the neutron star is investigated by means of deep dedicated observations obtained with the XMM-Newton Observatory, the ESO Very Large Telescope, as well as publicly available γ-ray data from the Fermi Space Telescope and the AGILE Mission. The observations confirm previous expectations and reveal a unique type of object. The source, which is likely within the Carina Nebula (N H = 2.6 × 10 21 cm −2 ), has a spectrum that is both thermal and soft, with kT ∞ = 135 eV. Non-thermal (magnetospheric) emission is not detected down to 1% (3σ, 0.1-12 keV) of the source luminosity. Significant deviations (absorption features) from a simple blackbody model are identified in the spectrum of the source around energies 0.6 keV and 1.35 keV. While the former deviation is likely related to a local oxygen overabundance in the Carina Nebula, the latter can only be accounted for by an additional spectral component, which is modelled as a Gaussian line in absorption with EW = 91 eV and σ = 0.14 keV (1σ). Furthermore, the optical counterpart is fainter than m V = 27 (2σ) and no γ-ray emission is significantly detected by either the Fermi or AGILE missions. Very interestingly, while these characteristics are remarkably similar to those of the M7 or the only RRAT so far detected in X-rays, which all have spin periods of a few seconds, we found intriguing evidence of very rapid rotation, P = 18.6 ms, at the 4σ confidence level. We interpret these new results in the light of the observed properties of the currently known neutron star population, in particular those of standard rotation-powered pulsars, recycled objects, and CCOs. We find that none of these scenarios can satisfactorily explain the collective properties of 2XMM J104608.7-594306, although it may be related to the still poorly known class of Galactic anti-magnetars. Future XMM-Newton data, granted for the next cycle of observations (AO11), will help us to improve our current observational interpretation of the source, enabling us to significantly constrain the rate of pulsar spin down.

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THE X-RAY COUNTERPART OF THE HIGH-BPULSAR PSR J0726–2612

Cited by 18 publications

References 56 publications

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

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

The compactness of the isolated neutron star RX J0720.4−3125

The peculiar isolated neutron star in the Carina Nebula

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