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

Jaisawal, Gaurava K.; Naik, Sachindra; Paul, Biswajit

doi:10.1088/0004-637x/779/1/54

Cited by 13 publications

(19 citation statements)

References 37 publications

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“…We observed a complex, broad profile in soft X-rays that evolves into a narrow emission peak followed by plateau like structure in hard X-rays. Almost similar energy evolution and pulse morphology were detected in the earlier studies (Fürst et al 2011(Fürst et al , 2012Jaisawal et al 2013). The existence of anomalous pulse profiles at several epochs advocates the persistent emission geometry of the pulsar.…”

Section: Pulse Profile and Spectroscopysupporting

confidence: 77%

“…The pulse profile of the pulsar is known to be strongly energy dependent. It evolves from a broad structure in soft X-rays to a narrow peak at higher energies (Fürst et al 2011(Fürst et al , 2012Jaisawal et al 2013). Broad-band energy spectrum of the pulsar is consistent with an absorbed high energy cutoff power law model along with a blackbody component (Fürst et al 2011(Fürst et al , 2012Jaisawal et al 2013).…”

Section: Introductionmentioning

confidence: 92%

“…Observed wind velocity of the optical companion is also shown in the grey range. The dashed horizontal line (green) corresponds to the magnetic field estimated by a tentative estimation of cyclotron line (Jaisawal et al 2013) .…”

Section: Magnetic Field Strength Of the Neutron Starmentioning

confidence: 99%

“…It evolves from a broad structure in soft X-rays to a narrow peak at higher energies (Fürst et al 2011(Fürst et al , 2012Jaisawal et al 2013). Broad-band energy spectrum of the pulsar is consistent with an absorbed high energy cutoff power law model along with a blackbody component (Fürst et al 2011(Fürst et al , 2012Jaisawal et al 2013). Based on a possible/tentative detection of cyclotron absorption line at ∼44 keV (Jaisawal et al 2013), the magnetic field of the neutron star is estimated to be ∼3.8×10 12 G. Superorbital modula- tion at a period of 15.2 days is also known from the system (Corbet & Krimm 2013).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Pulse Profile and Spectroscopysupporting

confidence: 77%

Section: Introductionmentioning

confidence: 92%

Section: Magnetic Field Strength Of the Neutron Starmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…The orbital phase resolved spectroscopy reveals an increase of the photoabsorption by a factor of 3 or more reaching values of N H ∼ f ew × 10 23 cm −2 around orbital phase 0 . Possible detection of the cyclotron scattering feature at 44 keV was reported by Jaisawal et al (2013) based on the Suzaku data. 4U 1909+07 is one of the few sources for which a superorbital modulation has been detected (the period of the modulation is 15.18 days; Corbet and Krimm, 2013).…”

Section: Discussionmentioning

confidence: 88%

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

234

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High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broadened significantly our understanding in particular for the super-giant systems in the Milky Way, which number has increased by almost a factor of three. INTEGRAL played a crucial role in the discovery, study and understanding of heavily obscured systems and of fast X-ray transients. Most super-giant systems can now be classified in three categories: classical/obscured, eccentric and fast transient.The classical systems feature low eccentricity and variability factor of ∼ 10 3 , mostly driven by hydrodynamic phenomena occurring on scales larger than the accretion radius. Among them, systems with short orbital periods and close to Roche-Lobe overflow or with slow winds, appear highly obscured. In eccentric systems, the variability amplitude can reach even higher factors, because of the contrast of the wind density along the orbit. Four super-giant systems, featuring fast outbursts, very short orbital periods and anomalously low accretion rates, are not yet understood.Simulations of the accretion processes on relatively large scales have progressed and reproduce parts of the observations. The combined effects of wind

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Cyclotron lines in highly magnetized neutron stars

Staubert

Trümper

Kendziorra

et al. 2019

A&A

244

221

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Cyclotron lines, also called cyclotron resonant scattering features (CRSF) are spectral features, generally appearing in absorption, in the X-ray spectra of objects containing highly magnetized neutron stars, allowing the direct measurement of the magnetic field strength in these objects. Cyclotron features are thought to be due to resonant scattering of photons by electrons in the strong magnetic fields. The main content of this contribution focusses on electron cyclotron lines as found in accreting X-ray binary pulsars (XRBP) with magnetic fields on the order of several 10 12 Gauss. Also, possible proton cyclotron lines from single neutron stars with even stronger magnetic fields are briefly discussed. With regard to electron cyclotron lines, we present an updated list of XRBPs that show evidence of such absorption lines. The first such line was discovered in a 1976 balloon observation of the accreting binary pulsar Hercules X-1, it is considered to be the first direct measurement of the magnetic field of a neutron star. As of today (mid 2018), we list 36 XRBPs showing evidence of one ore more electron cyclotron absorption line(s). A few have been measured only once and must be confirmed (several more objects are listed as candidates). In addition to the Tables of objects, we summarize the evidence of variability of the cyclotron line as a function of various parameters (especially pulse phase, luminosity and time), and add a discussion of the different observed phenomena and associated attempts of theoretical modeling. We also discuss our understanding of the underlying physics of accretion onto highly magnetized neutron stars. For proton cyclotron lines, we present tables with seven neutron stars and discuss their nature and the physics in these objects.

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

Cited by 13 publications

References 37 publications

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

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

High-mass X-ray binaries in the Milky Way

Cyclotron lines in highly magnetized neutron stars

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