Possible Phase-dependent Absorption Feature in the X-Ray Spectrum of the Middle-aged PSR J0659+1414

Arumugasamy, Prakash; Kargaltsev, Oleg; Posselt, Bettina; Pavlov, G. G.; Hare, Jeremy

doi:10.3847/1538-4357/aaec69

Cited by 23 publications

(66 citation statements)

References 65 publications

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“…Using XMM-Newton and NICER we firstly established an X-ray ephemeris for the time interval 2015 to 2020, which connects all X-ray observations in this period without cycle count alias and phase shifts. The mean eROSITA spectrum clearly reveals an absorption feature originating from the star at 570 eV with a Gaussian σ of about 70 eV, tentatively identified earlier in a long XMM-Newton observation (Arumugasamy et al 2018). A second absorption feature, described here as an absorption edge, occurs at 260 − 265 eV.…”

supporting

confidence: 77%

“…The most recent account of the phase-averaged X-ray spectrum of B0656 was given by Zharikov et al (2021), who on the one hand confirmed the earlier spectral model by Arumugasamy et al (2018), but also refined it through the inclusion of infrared/optical/ultraviolet data (IR/opt/UV). The spectral energy distribution established in this paper is best described by a broken power law from the magnetosphere plus the double blackbody with superposed absorption line at ∼0.5 keV originating from the stellar surface.…”

Section: Introduction Psr B0656+14 (Hereafter B0656mentioning

confidence: 83%

“…The times-of-arrival of the photons were converted from the local satellite to the solar system barycentric frame using the HEASOFT task barycen, the JPL-DE405 ephemeris table, the target coordinates from Arumugasamy et al (2018), and a suitable orbit file covering the epoch of the observation. For the latter, we converted the file with information on the spacecraft position and velocity as provided by NPOL to the FITS format required by barycen.…”

Section: Srg/erositamentioning

confidence: 99%

“…The much improved photon counting statistics allowed for the first time to trace the various spectral components through the spin cycle of the P rot 385 msec pulsar with the two blackbody-components varying in antiphase. Recently, Arumugasamy et al (2018) reported a possible phase-dependent absorption feature with central energy between 0.5 − 0.6 keV in coordinated XMM-Newton/NuSTARobservations. The inclusion of a Gaussian absorption line for roughly 50% of the spin cycle improved the phenomenological model.…”

Section: Introduction Psr B0656+14 (Hereafter B0656mentioning

confidence: 99%

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Phase-resolved X-ray spectroscopy of PSR B0656+14 with SRG/eROSITA and XMM-Newton

Schwope,

Pires,

Kurpas

et al. 2021

Preprint

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We present a detailed spectroscopic and timing analysis of X-ray observations of the bright radio-to-gamma-ray emitting pulsar PSR B0656+14, which were obtained simultaneously with eROSITA and XMM-Newton during the Calibration and Performance Verification phase of the Spektrum-Roentgen-Gamma mission (SRG). The analysis of the 100 ks-deep observation of eROSITA is supported by archival and simultaneous observations of the source, including XMM-Newton, NuSTAR, and NICER. Using XMM-Newton and NICER we firstly established an X-ray ephemeris for the time interval 2015 to 2020, which connects all X-ray observations in this period without cycle count alias and phase shifts. The mean eROSITA spectrum clearly reveals an absorption feature originating from the star at 570 eV with a Gaussian σ of about 70 eV, tentatively identified earlier in a long XMM-Newton observation (Arumugasamy et al. 2018). A second absorption feature, described here as an absorption edge, occurs at 260 − 265 eV. It could be of atmospheric or of instrumental origin. These absorption features are superposed on various emission components, phenomenologically described here as the sum of hot (120 eV) and cold (65 eV) blackbody components, both of photospheric origin, and a power-law with photon index Γ = 2 from the magnetosphere. We created energy-dependent lightcurves and phase-resolved spectra with high signal-to-noise. The phase-resolved spectroscopy reveals that the Gaussian absorption line at 570 eV is clearly present throughout ∼60% of the spin cycle, but undetected otherwise. Likewise, its parameters were found to be dependent on phase. The visibility of the line strength coincides in phase with the maximum flux of the hot blackbody. If the line originates from the stellar surface, it nevertheless likely originates from a different location than the hot polar cap. We also present three families of model atmospheres: a magnetised atmosphere, a condensed surface, and a mixed model, which were applied to the mean observed spectrum and whose continuum fit the observed data well. The atmosphere model, however, predicts too short distances. For the mixed model, the Gaussian absorption may be interpreted as proton cyclotron absorption in a field as high as 10 14 G, which is significantly higher than that derived from the moderate observed spin-down.

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supporting

confidence: 77%

Section: Introduction Psr B0656+14 (Hereafter B0656mentioning

confidence: 83%

Section: Srg/erositamentioning

confidence: 99%

Section: Introduction Psr B0656+14 (Hereafter B0656mentioning

confidence: 99%

See 2 more Smart Citations

Phase-resolved X-ray spectroscopy of PSR B0656+14 with SRG/eROSITA and XMM-Newton

Schwope,

Pires,

Kurpas

et al. 2021

Preprint

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“…So, among the remaining 9 pulsars, none of them show definitive evidence for isotropic emission of a BB. On the contrary, for pulsars with high S/N data, the pulse profiles are sharper and non-sinusoidal in the energy range where the polar cap emission dominates often with high pulsed fractions or increasing pulsed fraction with energy (PSR B0656+14; De Luca et al 2005;Arumugasamy et al 2018De Luca et al 2005Kargaltsev et al 2005). These are indicative of beamed (anisotropic) emission significantly deviating from a BB.…”

Section: Discussionmentioning

confidence: 99%

Evaluating the evidence of multipolar surface magnetic field in PSR J0108–1431

Arumugasamy

Mitra

2019

Monthly Notices of the Royal Astronomical Society

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PSR J0108-1431 is an old pulsar where the X-ray emission is expected to have a thermal component from the polar cap and a non-thermal component from the magnetosphere. Although the phase-integrated spectra are fit best with a single non-thermal component modeled with a power-law (PL) of photon index Γ = 2.9, the X-ray pulse profiles do show the presence of phase-separated thermal and non-thermal components. The spectrum extracted from half the rotational phase away from the X-ray peak fits well with either a single blackbody (BB) or a neutron star atmosphere (NA) model, whereas, the spectrum from the rest of the phase range is dominated by a PL. From Bayesian analysis, the estimated BB area is smaller than the expected polar cap area for a dipolar magnetic field with a probability of 86% whereas the area estimate from the NA model is larger with a probability of 80%. Due to the ambiguity in the thermal emission model, the polar cap area cannot be reliably estimated and hence cannot be used to understand the nature of the surface magnetic field. Instead, we can infer the presence of multipolar magnetic field from the misalignment between the pulsar's thermal X-ray peak and the radio emission peak. For J0108-1431, we estimated a phase-offset ∆φ > 0.1 between the thermal polar cap emission peak and the radio emission peak and argue that this is best explained by the presence of a multipolar surface magnetic field.

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Detailed X-ray spectroscopy of the magnetar 1E 2259+586

Pizzocaro

Tiengo

Mereghetti

et al. 2019

A&A

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Magnetic field geometry is expected to play a fundamental role in magnetar activity. The discovery of a phase-variable absorption feature in the X-ray spectrum of SGR 0418+5729, interpreted as cyclotron resonant scattering, suggests the presence of very strong non-dipolar components in the magnetic fields of magnetars. We performed a deep XMM-Newton observation of pulsar 1E 2259+586 to search for spectral features due to intense local magnetic fields. In the phase-averaged X-ray spectrum, we found evidence for a broad absorption feature at very low energy (0.7 keV ). If the feature is intrinsic to the source, it might be due to resonant scattering and absorption by protons close to star surface. The line energy implies a magnetic field of ∼ 10 14 G, which is roughly similar to the spin-down measure, ∼ 6 × 10 13 G. Examination of the X-ray phase-energy diagram shows evidence for another absorption feature, the energy of which strongly depends on the rotational phase (E > ∼ 1 keV ). Unlike similar features detected in other magnetar sources, notably SGR 0418+5729, it is too shallow and limited to a short phase interval to be modeled with a narrow phase-variable cyclotron absorption line. A detailed phase-resolved spectral analysis reveals significant phase-dependent variability in the continuum, especially above 2 keV . We conclude that all the variability with phase in 1E 2259+586 can be attributed to changes in the continuum properties, which appear consistent with the predictions of the resonant Compton scattering model.

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Possible Phase-dependent Absorption Feature in the X-Ray Spectrum of the Middle-aged PSR J0659+1414

Cited by 23 publications

References 65 publications

Phase-resolved X-ray spectroscopy of PSR B0656+14 with SRG/eROSITA and XMM-Newton

Phase-resolved X-ray spectroscopy of PSR B0656+14 with SRG/eROSITA and XMM-Newton

Evaluating the evidence of multipolar surface magnetic field in PSR J0108–1431

Detailed X-ray spectroscopy of the magnetar 1E 2259+586

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