A Suzaku view of cyclotron line sources and candidates

Pottschmidt, K.; Suchy, S.; Rivers, Elizabeth; Rothschild, R. E.; Marcu, D. M.; Barragán, L.; Kühnel, Matthias; Fürst, Felix; Schwarm, Fritz; Kreykenbohm, I.; Wilms, J.; Schönherr, G.; Caballero, I.; Camero-Arranz, A.; Bodaghee, A.; Doroshenko, V.; Klochkov, D.; Santangelo, A.; Staubert, R.; Kretschmar, P.; Wilson-Hodge, C.; Finger, Mark H.; Terada, Y.

doi:10.1063/1.3696152

Cited by 11 publications

(9 citation statements)

References 14 publications

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“…They were first detected from the accreting X-ray pulsar, Hercules X-1 (Trümper et al 1978). About 20 such systems have since been detected (Caballero & Wilms 2012;Pottschmidt et al 2012;and references therein). The high surface magnetic field of these pulsars (B = 10 12 − 10 13 G) causes the charged particles in the accreting plasma to absorb the NS continuum emission at energies between 10 − 100 keV via the cyclotron mechanism.…”

Section: Introductionmentioning

confidence: 99%

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

Arumugasamy

Kargaltsev

Posselt

et al. 2018

ApJ

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We report on the energy-resolved timing and phase-resolved spectral analysis of X-ray emission from PSR J0659+1414 observed with XMM-Newton and NuSTAR. We find that the new data rule out the previously suggested model of the phase-dependent spectrum as a three-component (2 blackbodies + power-law) continuum, which shows large residuals between 0.3 − 0.7 keV. Fitting neutron star atmosphere models or several blackbodies to the spectrum does not provide a better description of the spectrum, and requires spectral model components with unrealistically large emission region sizes. The fits improve significantly if we add a phase-dependent absorption feature with central energy 0.5 − 0.6 keV and equivalent width up to ≈ 50 eV. We detected the feature for about half of the pulse cycle. Energy-resolved pulse profiles support the description of the spectrum with a three-component continuum and an absorption component. The absorption feature could be interpreted as an electron cyclotron line originating in the pulsar magnetosphere and broadened by the non-uniformity of magnetic field along the line of sight. The significant phase-variability in the thermal emission from the entire stellar surface may indicate multi-polar magnetic fields and a nonuniform temperature distribution. The strongly pulsed non-thermal spectral component detected with NuSTAR in the 3-20 keV range is well fit by a power-law model with a photon index Γ = 1.5 ± 0.2.

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Section: Introductionmentioning

confidence: 99%

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

Arumugasamy

Kargaltsev

Posselt

et al. 2018

ApJ

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“…Detection of CRSF in the spectrum, therefore, provides the direct measurement of the strength of the pulsar magnetic field. The CRSFs have been detected in the spectrum of about 19 X-ray pulsars (Coburn et al 2002;Staubert et al 2003;Pottschmidt et al 2012) using data from several X-ray observatories. The harmonics of fundamental cyclotron absorption line are also detected in some pulsars (Nakajima et al 2006;Orlandini et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Possible Detection of a Cyclotron Resonance Scattering Feature in the X-Ray Pulsar 4u 1909+07

Jaisawal

Naik

Paul

2013

ApJ

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We present timing and broad band spectral studies of the high-mass X-ray binary pulsar 4U 1909+07 using data from Suzaku observations during 2010 November 2-3. The pulse period of the pulsar is estimated to be 604.11 ± 0.14 s. Pulsations are seen in the X-ray light curve up to ∼70 keV. The pulse profile is found to be strongly energydependent: a complex, multi-peaked structure at low energy becomes a simple single peak at higher energy. We found that the 1-70 keV pulse-averaged continuum can be fit by the sum of a blackbody and a partial covering Negative and Positive power law with Exponential cutoff model. A weak iron fluorescence emission line at 6.4 keV was detected in the spectrum. An absorption-like feature at ∼44 keV was clearly seen in the residuals of the spectral fitting, independent of the continuum model adopted. To check the possible presence of a cyclotron resonance scattering feature (CRSF) in the spectrum, we normalized the pulsar spectrum with the spectrum of the Crab Nebula. The resulting Crab ratio also showed a clear dip centered at ∼44 keV. We performed statistical tests on the residuals of the spectral fitting and also on the Crab spectral ratio to determine the significance of the absorption-like feature and identified it as a CRSF of the pulsar. We estimated the corresponding surface magnetic field of the pulsar to be 3.8 × 10 12 G.

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“…Observing cyclotron lines in the spectra of these systems is the only direct way to measure the magnetic field strengths of neutron stars. At the time of writing there are sixteen neutron star X-ray binaries with confirmed CRSFs (Heindl et al 2004;Caballero & Wilms 2012;Pottschmidt et al 2012, and references therein), eight of which are transients (Swift J1626.6−5156 being the ninth). Of the transients four systems are BeX binaries (Swift J1626.6−5156 being the fifth) and four are OeX binaries.…”

Section: Introductionmentioning

confidence: 99%

THE Be/X-RAY BINARY SWIFT J1626.6–5156 AS A VARIABLE CYCLOTRON LINE SOURCE

DeCesar

Boyd

Pottschmidt

et al. 2012

ApJ

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Swift J1626.6−5156 is a Be/X-ray binary that was in outburst from December 2005 until November 2008. We have examined RXTE/PCA and HEXTE spectra of three long observations of this source taken early in its outburst, when the PCA 2-20 keV count rate was >70 counts s −1 PCU −1 , as well as several combined observations from different stages of the outburst. The spectra are best fit with an absorbed cutoff power law with a ∼ 6.4 keV iron emission line and a Gaussian optical depth absorption line at ∼10 keV. We present strong evidence that this absorption-like feature is a cyclotron resonance scattering feature, making Swift J1626.6−5156 a new candidate cyclotron line source. The redshifted energy of ∼10 keV implies a magnetic field strength of ∼ 8.6(1 + z) × 10 11 G in the region of the accretion column close to the magnetic poles where the cyclotron line is produced. Analysis of phase averaged spectra spanning the duration of the outburst suggests a possible positive correlation between the fundamental cyclotron energy and source luminosity. Phase resolved spectroscopy from a long observation reveals a variable cyclotron line energy, with phase dependence similar to a variety of other pulsars, as well as the first harmonic of the fundamental cyclotron line.

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A Suzaku view of cyclotron line sources and candidates

Cited by 11 publications

References 14 publications

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

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

Possible Detection of a Cyclotron Resonance Scattering Feature in the X-Ray Pulsar 4u 1909+07

THE Be/X-RAY BINARY SWIFT J1626.6–5156 AS A VARIABLE CYCLOTRON LINE SOURCE

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