Staring at 4U 1909+07 with<i>Suzaku</i>

Fürst, Felix; Pottschmidt, K.; Kreykenbohm, I.; Müller, Sebastian; Kühnel, Matthias; Wilms, J.; Rothschild, R. E.

doi:10.1051/0004-6361/201219845

Cited by 12 publications

(26 citation statements)

References 24 publications

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“…The addition of high energy cut-off to the partial covering power-law model fitted data well with the black-body temperature of ∼0.2 keV. The parameters obtained by fitting the partial covering high energy cut-off power-law model to the spectrum are in good agreement with Table 2 of Fürst et al (2012). However, the partial covering NPEX continuum model with iron line and black-body component described the spectrum better yielding an acceptable black-body temperature of 0.2 keV.…”

Section: Spectral Analysissupporting

confidence: 72%

“…The pulse profile was found to be strongly energy dependent. The phase averaged spectrum, obtained from above observations, were well described by a power-law with high energy cut-off continuum model along with a black-body component (Fürst et al 2011). Fürst et al (2012 also analyzed data from Suzaku observation of the pulsar and described the spectrum using same model as was used in case of their earlier work.…”

Section: Introductionmentioning

confidence: 61%

“…It can be seen from the table that addition of a CRSF at ∼44 keV improved the spectral fitting in all cases. The same Suzaku observation was analyzed, although with the ISIS package, by Fürst et al (2012). These authors did not use HXD/GSO data because of possible contamination from the nearby source GRS 1915+105, and therefore performed their spectral analysis in the 1-40 keV energy range.…”

Section: Spectral Analysismentioning

confidence: 99%

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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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Section: Spectral Analysissupporting

confidence: 72%

Section: Introductionmentioning

confidence: 61%

Section: Spectral Analysismentioning

confidence: 99%

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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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“…Long term timing studies showed that the spin period of the pulsar changes erratically on years time scale. It is only possible when mass accretion through the capture of stellar wind occurs in the system (Fürst et al 2011(Fürst et al , 2012. A similar conclusion was drawn based on the detection of the Compton shoulder in the iron fluorescence line.…”

Section: Introductionmentioning

confidence: 75%

Revisiting the spectral and timing properties of 4U 1909+07 with NuSTAR and Astrosat

Jaisawal

Naik

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present the results obtained from the analysis of high mass X-ray binary pulsar 4U 1909+07 using NuSTAR and Astrosat observations in 2015 and 2017 July, respectively. X-ray pulsations at ≈604 s are clearly detected in our study. Based on the long term spin-frequency evolution, the source is found to spun up in the last 17 years. We observed a strongly energy-dependent pulse profile that evolved from a complex broad structure in soft X-rays into a profile with a narrow emission peak followed by a plateau in energy ranges above 20 keV. This behaviour ensured a positive correlation between the energy and pulse fraction. The pulse profile morphology and its energy-evolution are almost similar during both the observations, suggesting a persistent emission geometry of the pulsar over time. The broadband energy spectrum of the pulsar is approximated by an absorbed high energy exponential cutoff power law model with iron emission lines. In contrast to the previous report, we found no statistical evidence for the presence of cyclotron absorption features in the X-ray spectra. We performed phase-resolved spectroscopy by using data from the NuSTAR observation. Our results showed a clear signature of absorbing material at certain pulse-phases of the pulsar. These findings are discussed in terms of stellar wind distribution and its effect on the beam geometry of this wind-fed accreting neutron star. We also reviewed the subsonic quasi-spherical accretion theory and its implication on the magnetic field of 4U 1909+07 depending on the global spin-up rate.

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“…We constructed radial profiles for the three observations of Vela X-1 (Fürst et al 2014) for the energy bands used above, and compared the radial profiles directly for each radial bin. We subtracted the late-time profiles from the reference profile (T=0, obs.…”

Section: Off-axis Psfmentioning

confidence: 99%

CALIBRATION OF THE NuSTAR HIGH-ENERGY FOCUSING X-RAY TELESCOPE

Madsen

Harrison

Markwardt

et al. 2015

ApJS

335

266

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We present the calibration of the Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray satellite. We used the Crab as the primary effective area calibrator and constructed a piece-wise linear spline function to modify the vignetting response. The achieved residuals for all off-axis angles and energies, compared to the assumed spectrum, are typically better than ±2% up to 40 keV and 5-10 % above due to limited counting statistics. An empirical adjustment to the theoretical 2D point spread function (PSF) was found using several strong point sources, and no increase of the PSF half power diameter (HPD) has been observed since the beginning of the mission. We report on the detector gain calibration, good to 60 eV for all grades, and discuss the timing capabilities of the observatory, which has an absolute timing of ± 3 ms. Finally we present cross-calibration results from two campaigns between all the major concurrent X-ray observatories (Chandra, Swift, Suzaku and XMM-Newton), conducted in 2012 and 2013 on the sources 3C 273 and PKS 2155-304, and show that the differences in measured flux is within ∼10% for all instruments with respect to NuSTAR. Subject headings: space vehicles: instruments -X-rays: individual (3C 273) -X-rays: individual (PKS 2155-304)

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Staring at 4U 1909+07 withSuzaku

Cited by 12 publications

References 24 publications

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

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

Revisiting the spectral and timing properties of 4U 1909+07 with NuSTAR and Astrosat

CALIBRATION OF THE NuSTAR HIGH-ENERGY FOCUSING X-RAY TELESCOPE

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