New observations of the cyclotron absorption feature in Hercules X–1

Mihara, T.; Makishima, Kazuo; Ohashi, T.; Sakao, Taro; Tashiro, M.; Nagase, F.; Tanaka, Yasuo; Kitamoto, Shunji; Miyamoto, S.; Deeter, J. E.; Boynton, P. E.

doi:10.1038/346250a0

Cited by 149 publications

(123 citation statements)

References 19 publications

Supporting

Mentioning

116

Contrasting

Order By: Relevance

“…Note, that the cyclotron line energy derived from the cyclabs model is systematically lower (by ∼1-3 keV) than the energy derived from the gabs model (see e.g. Mihara 1995;Nakajima et al 2010;Tsygankov et al 2012).…”

Section: Correlations Between the Parameters Of The Cyclotron Linementioning

confidence: 99%

“…The spectrum was modified by one or several cyclotron absorption lines in the form where E N , σ N and τ N are the energy, width and depth of the cyclotron line (N = 0) and harmonics (N > 0), respectively (cyclabs in the xspec package; Mihara et al 1990). The same model was used earlier for the analysis of pulse-phase averaged spectra and reasons for the choice of the continuum and line models were discussed by Tsygankov et al (2006Tsygankov et al ( , 2010.…”

Section: Observations Spectral Model and Data Analysismentioning

confidence: 99%

“…A study of the source pulse-averaged spectra showed that the cyclotron line energy, as well as parameters of the spectral continuum, significantly change with the source luminosity (Tsygankov et al 2006; Mowlavi et al 2006;Tsygankov et al 2010;Nakajima et al 2010) along the outburst. This behaviour was interpreted as a result of changes in the height of the accretion column where the cyclotron absorption line was assumed to originate (see, e.g., Mihara 1995;Schönherr et al 2007;Nishimura 2008Nishimura , 2014Becker et al 2012, and references therein). However, alternative scenario has recently been proposed by Poutanen et al (2013), where the line forms in the illuminated atmosphere of the neutron star.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Transient X-ray pulsar V 0332+53: pulse-phase-resolved spectroscopy and the reflection model

Lutovinov¹,

Tsygankov²,

Suleimanov³

et al. 2015

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present the results of the pulse phase-and luminosity-resolved spectroscopy of the transient X-ray pulsar V 0332+53, performed for the first time in a wide luminosity range (1 − 40) × 10 37 erg s −1 during a giant outburst observed by the RXTE observatory in Dec 2004 -Feb 2005. We characterize the spectra quantitatively and built the detailed "threedimensional" picture of spectral variations with pulse phase and throughout the outburst. We show that all spectral parameters are strongly variable with the pulse phase, and the pattern of this variability significantly changes with luminosity directly reflecting the associated changes in the structure of emission regions and their beam patterns. Obtained results are qualitatively discussed in terms of the recently developed reflection model for the formation of cyclotron lines in the spectra of X-ray pulsars.

show abstract

Section: Correlations Between the Parameters Of The Cyclotron Linementioning

confidence: 99%

Section: Observations Spectral Model and Data Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transient X-ray pulsar V 0332+53: pulse-phase-resolved spectroscopy and the reflection model

Lutovinov¹,

Tsygankov²,

Suleimanov³

et al. 2015

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…The two most common CRSF models are those using a Gaussian or a pseudoLorentzian profile (see discussion by Nakajima et al 2010). Here, we model the CRSFs with a pseudo-Lorentzian optical depth profile (Mihara et al 1990), i.e., we multiply the continuum model with…”

Section: Pulsar Continuum Modelsmentioning

confidence: 99%

No anticorrelation between cyclotron line energy and X-ray flux in 4U 0115+634

Müller

Ferrigno

Kühnel

et al. 2013

A&A

View full text Add to dashboard Cite

We report on an outburst of the high mass X-ray binary 4U 0115+634 with a pulse period of 3.6 s in 2008 March/April as observed with RXTE and INTEGRAL. During the outburst the neutron star's luminosity varied by a factor of 10 in the 3-50 keV band. In agreement with earlier work we find evidence of five cyclotron resonance scattering features at ∼10.7, 21.8, 35.5, 46.7, and 59.7 keV. Previous work had found an anticorrelation between the fundamental cyclotron line energy and the X-ray flux. We show that this apparent anticorrelation is probably due to the unphysical interplay of parameters of the cyclotron line with the continuum models used previously, e.g., the negative and positive exponent power law (NPEX). For this model, we show that cyclotron line modeling erroneously leads to describing part of the exponential cutoff and the continuum variability, and not the cyclotron lines. When the X-ray continuum is modeled with a simple exponentially cutoff power law modified by a Gaussian emission feature around 10 keV, the correlation between the line energy and the flux vanishes, and the line parameters remain virtually constant over the outburst. We therefore conclude that the previously reported anticorrelation is an artifact of the assumptions adopted in the modeling of the continuum.

show abstract

“…The third is the negative and positive exponential cutoff power-law (NPEX) model (Mihara 1995;Makishima et al 1999),…”

Section: Spectral Modelmentioning

confidence: 99%

SHORT-TERM VARIABILITY OF X-RAYS FROM ACCRETING NEUTRON STAR VELA X-1. I.SUZAKUOBSERVATIONS

Odaka

Khangulyan

Tanaka

et al. 2013

ApJ

View full text Add to dashboard Cite

We have analyzed the time variability of the wide-band X-ray spectrum of Vela X-1, the brightest wind-fed accreting neutron star, on a short timescale of 2 ks by using Suzaku observations with an exposure of 100 ks. During the observation, the object showed strong variability, including several flares and so-called "low states," in which the X-ray luminosity decreases by an order of magnitude. Although the spectral hardness increases with the X-ray luminosity, the majority of the recorded flares do not show any significant changes in circumstellar absorption. However, a sign of heavy absorption was registered immediately before one short flare that showed a significant spectral hardening. In the low states, the flux level is modulated with the pulsar spin period, indicating that even at this state the accretion flow reaches the close proximity of the neutron star. Phenomenologically, the broadband X-ray spectra, which are integrated over the entire spin phase, are well represented by the "NPEX" function (a combination of negative and positive power laws with an exponential cutoff by a common folding energy) with a cyclotron resonance scattering feature at 50 keV. Fitting of the data allowed us to infer a correlation between the photon index and X-ray luminosity. Finally, the circumstellar absorption shows a gradual increase in the orbital phase interval 0.25-0.3, which can be interpreted as an impact of a bow shock imposed by the motion of the compact object in the supersonic stellar wind.

show abstract

New observations of the cyclotron absorption feature in Hercules X–1

Cited by 149 publications

References 19 publications

Transient X-ray pulsar V 0332+53: pulse-phase-resolved spectroscopy and the reflection model

Transient X-ray pulsar V 0332+53: pulse-phase-resolved spectroscopy and the reflection model

No anticorrelation between cyclotron line energy and X-ray flux in 4U 0115+634

SHORT-TERM VARIABILITY OF X-RAYS FROM ACCRETING NEUTRON STAR VELA X-1. I.SUZAKUOBSERVATIONS

Contact Info

Product

Resources

About