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Luminosity-dependent changes of the cyclotron line energy and spectral hardness in Cep X-4

X-ray spectra of accreting pulsars are generally observed to vary with their X-ray luminosity. In particular, the hardness of the X-ray continuum is found to depend on luminosity. In a few sources, the correlation between the energy of the…

High Energy Astrophysical Phenomena · Physics 2017-02-22 V. Vybornov , D. Klochkov , M. Gornostaev , K. Postnov , E. Sokolova-Lapa , R. Staubert , K. Pottschmidt , A. Santangelo

Energy-resolved pulse profile changes in V 0332+53: Indications of wings in the cyclotron absorption line profile

We aim to investigate the energy-resolved pulse profile changes of the accreting X-ray pulsar V 0332+53, focusing in the cyclotron line energy range, using the full set of available NuSTAR observations. We applied a tailored pipeline to…

High Energy Astrophysical Phenomena · Physics 2025-02-26 Antonino D'Aì , Dimitrios K. Maniadakis , Carlo Ferrigno , Elena Ambrosi , Ekaterina Sokolova-Lapa , Giancarlo Cusumano , Peter A. Becker , Luciano Burderi , Melania Del Santo , Tiziana Di Salvo , Felix Fürst , Rosario Iaria , Peter Kretschmar , Valentina La Parola , Christian Malacaria , Ciro Pinto , Fabio Pintore , A. Guillermo Rodriguez-Castillo

On the cyclotron line in Cep X-4

Accreting X-ray pulsars provide us with laboratories for the study of extreme gravitational and magnetic fields, hence accurate descriptions of their observational properties contribute to our understanding of this group of objects. We aim…

Astrophysics · Physics 2009-11-13 V. A. McBride , J. Wilms , I. Kreykenbohm , M. J. Coe , R. E. Rothschild , P. Kretschmar , K. Pottschmidt , J. Fisher , T. Hamson

Timing and spectral variability of high mass X-ray pulsar GX 301--2 over orbital phases observed by Insight-HXMT

We report the orbital X-ray variability of high mass X-ray binary (HMXB) GX301--2. GX301--2 undergone a spin up process in 2018--2020 with the period evolving from $\sim$ 685 s to 670 s. The energy resolved pulse-profiles of the pulsar in…

High Energy Astrophysical Phenomena · Physics 2022-08-24 Y. Z. Ding , W. Wang , P. R. Epili , Q. Liu , M. Y. Ge , F. J. Lu , J. L. Qu , L. M. Song , S. Zhang , S. N. Zhang

Study of the X-ray pulsar IGR J19294+1816 with NuSTAR: detection of cyclotron line and transition to accretion from the cold disc

In the work we present the results of two deep broad-band observations of the poorly studied X-ray pulsar IGR J19294+1816 obtained with the NuSTAR observatory. The source was observed during Type I outburst and in the quiescent state. In…

High Energy Astrophysical Phenomena · Physics 2019-01-23 Sergey S. Tsygankov , Victor Doroshenko , Alexander A. Mushtukov , Alexander A. Lutovinov , Juri Poutanen

NuSTAR Discovery of a cyclotron line in KS 1947+300

We present a spectral analysis of three simultaneous NuSTAR and Swift/XRT observations of the transient Be-neutron star binary KS 1947+300 taken during its outburst in 2013/2014. These broad-band observations were supported by Swift/XRT…

High Energy Astrophysical Phenomena · Physics 2019-08-19 Felix Fuerst , Katja Pottschmidt , Joern Wilms , Jamie Kennea , Matteo Bachetti , Eric Bellm , Steven E. Boggs , Deepto Chakrabarty , Finn E. Christensen , William W. Craig , Charles J. Hailey , Fiona Harrison , Daniel Stern1 , John A. Tomsick , Dominic J. Walton , William Zhang , Cahill Center , Caltech , USA , CSST , UMBC , USA , CRESST , GSFC , USA , Remeis-Observatory , ECAP , Germany , Penn State University , USA , Universite de Toulouse , France , CNRS , IRAP , France , SSL , UCB , USA , Kavli Institute for Astrophysics , MIT , USA , DTU Space , TU Denmark , Denmark , Columbia Astrophysics Lab , Columbia University , USA , JPL , USA , GSFC , ASD , USA

Cylotron line models for the X-ray pulsar A0535+26

The spectrum of the transient X-ray binary pulsar A0535+26 obtained by OSSE in February 1994 shows an absorption feature at 110 keV but does not confirm a feature at around 55 keV, as previously reported by other instruments. If the 110 keV…

Astrophysics · Physics 2007-05-23 R. A. Araya , A. K. Harding

Evidence for neutron star triaxial free precession in Her X-1 from Fermi/GBM pulse period measurements

Her X-1/HZ Her is one of the best studied accreting X-ray pulsars. In addition to the pulsating and orbital periods, the X-ray and optical light curves of the source exhibit an almost periodic 35-day variability caused by a precessing…

High Energy Astrophysical Phenomena · Physics 2022-04-27 Dmitry Kolesnikov , Nikolai Shakura , Konstantin Postnov

X-ray Variability and Period Determinations in the Eclipsing Polar DP Leo

An analysis of ROSAT observations for the eclipsing magnetic cataclysmic binary DP Leo provides constraints on the origin, size, temperature, variability and structure of the soft X-ray emission region on the surface of the white dwarf.…

Astrophysics · Physics 2009-10-22 C. R. Robinson , F. A. Cordova

Theoretical Constraints on Neutron Star Superfluidity from Her X-1 Precession

Recent IXPE observations of Her X-1 reveal correlations between flux, polarization degree, and polarization angle across its 35-day superorbital cycle. These measurements have been interpreted as strong evidence that the 35-day period is…

High Energy Astrophysical Phenomena · Physics 2026-05-08 Anton Biryukov , Amir Levinson , Pavel Abolmasov

Variable precession of the neutron star in Her X-1

We present evidence for an identical behavior of the precession of the accretion disk and that of the neutron star (NS) in Her X-1, based on investigating the well established 35 day modulation in Her X-1 in two different ways: 1) following…

High Energy Astrophysical Phenomena · Physics 2015-05-14 R. Staubert , D. Klochkov , K. Postnov , N. Shakura , J. Wilms , R. E. Rothschild

Insight-HXMT firm detection of the highest energy fundamental cyclotron resonance scattering feature in the spectrum of GRO J1008-57

We report on the observation of the accreting pulsar GRO J1008-57 performed by Insight-HXMT at the peak of the source's 2017 outburst. Pulsations are detected with a spin period of 93.283(1) s. The pulse profile shows double peaks at soft…

High Energy Astrophysical Phenomena · Physics 2020-08-19 M. Y. Ge , L. Ji , S. N. Zhang , A. Santangelo , C. Z. Liu , V. Doroshenko , R. Staubert , J. L. Qu , S. Zhang , F. J. Lu , L. M. Song , T. P. Li , L. Tao , Y. P. Xu , X. L. Cao , Y. Chen , Q. C. Bu , C. Cai , Z. Chang , G. Chen , L. Chen , T. X. Chen , Y. B. Chen , Y. P. Chen , W. Cui , W. W. Cui , J. K. Deng , Y. W. Dong , Y. Y. Du , M. X. Fu , G. H. Gao , H. Gao , M. Gao , Y. D. Gu , J. Guan , C. C. Guo , D. W. Han , Y. Huang , J. Huo , S. M. Jia , L. H. Jiang , W. C. Jiang , J. Jin , Y. J. Jin , L. D. Kong , B. Li , C. K. Li , G. Li , M. S. Li , W. Li , X. Li , X. B. Li , X. F. Li , Y. G. Li , Z. W. Li , X. H. Liang , J. Y. Liao , B. S. Liu , G. Q. Liu , H. W. Liu , X. J. Liu , Y. N. Liu , B. Lu , X. F. Lu , Q. Luo , T. Luo , X. Ma , B. Meng , Y. Nang , J. Y. Nie , G. Ou , N. Sai , R. C. Shang , X. Y. Song , L. Sun , Y. Tan , Y. L. Tuo , C. Wang , G. F. Wang , J. Wang , L. J. Wang , W. S. Wang , Y. D. Wang , Y. S. Wang , X. Y. Wen , B. B. Wu , B. Y. Wu , M. Wu , G. C. Xiao , S. Xiao , S. L. Xiong , H. Xu , J. W. Yang , S. Yang , Y. J. Yang , Y. J. Yang , Q. B. Yi , Q. Q. Yin , Y. You , A. M. Zhang , C. M. Zhang , F. Zhang , H. M. Zhang , J. Zhang , T. Zhang , W. C. Zhang , W. Zhang , W. Z. Zhang , Y. Zhang , Y. F. Zhang , Y. J. Zhang , Y. Zhang , Z. Zhang , Z. Zhang , Z. L. Zhang , H. S. Zhao , X. F. Zhao , S. J. Zheng , Y. G. Zheng , D. K. Zhou , J. F. Zhou , R. L. Zhuang , Y. X. Zhu , Y. Zhu

The X-ray pulsar XTE J1858+034 observed with NuSTAR and Fermi/GBM: spectral and timing characterization plus a cyclotron line

Accreting X-ray pulsars (XRPs) undergo luminous X-ray outbursts during which the spectral and timing behavior of the neutron star can be studied in detail. We analyze a $NuSTAR$ observation of the XRP XTE J1858+034 during its outburst in…

High Energy Astrophysical Phenomena · Physics 2021-03-24 C. Malacaria , P. Kretschmar , K. K. Madsen , C. A. Wilson-Hodge , Joel B. Coley , P. Jenke , A. A. Lutovinov , K. Pottschmidt , S. S. Tsygankov , J. Wilms

Cyclotron absorption lines in the era of Suzaku and NuSTAR

Cyclotron resonance scattering features or cyclotron absorption lines are unique features observed in the hard X-ray spectra of accretion powered X-ray pulsars with magnetic field of the order of 10$^{12}$ G. Detection of these features…

High Energy Astrophysical Phenomena · Physics 2017-05-17 Gaurava K. Jaisawal , Sachindra Naik

XMM-Newton EPIC observations of Her X-1

We present spin-resolved X-ray data of the neutron star binary Her X-1. We find evidence that the Iron line at 6.4 keV originates from the same location as the blackbody X-ray component. The line width and energy varies over both the spin…

Astrophysics · Physics 2007-05-23 G. Ramsay , S. Zane , M. A. Jimenez-Garate , J. W. den Herder , C. J. Hailey

The Photoionized Accretion Disk in Her X-1

We present an analysis of several high-resolution Chandra grating observations of the X-ray binary pulsar Her X-1. With a total exposure of 170 ks, the observations are separated by years and cover three combinations of orbital and…

High Energy Astrophysical Phenomena · Physics 2009-07-22 L. Ji , N. Schulz , M. Nowak , H. L. Marshall , T. Kallman

Spectral variations of the X-ray binary pulsar LMC X-4 during its long period intensity variation and a comparison with Her X-1

We present spectral variations of the binary X-ray pulsar LMC X-4 using the RXTE/PCA observations at different phases of its 30.5 day long super-orbital period. Only out of eclipse data were used for this study. During the high state of the…

Astrophysics · Physics 2011-05-23 S. Naik , B. Paul

Discovery of a Cyclotron Resonance Scattering Feature in the X-ray Spectrum of XTE J1946+274

Observations of the transient accreting pulsar XTE J1946+274 made with the Rossi X-ray Timing Explorer during the course of the 1998 September-November outburst, reveal a cyclotron resonance scattering feature (or "cyclotron line") in the…

Astrophysics · Physics 2009-11-07 W. A. Heindl , W. Coburn , D. E. Gruber , R. E. Rothschild , I. Kreykenbohm , J. Wilms , R. Staubert

Variations in the spin period of the radio-quiet pulsar 1E 1207.4-5209

The X-ray source 1E 1207.4-5209 is a compact central object in the G296.5+10.0 supernova remnant. Its spin period of 424 ms, discovered with the Chandra X-ray Observatory, suggests that it is a neutron star. The X-ray spectrum of this…

Astrophysics · Physics 2009-11-10 V. E. Zavlin , G. G Pavlov , D. Sanwal

Long Term Variability of Cygnus X-1. IV. Spectral Evolution 1999-2004

(abbreviated abstract) We present the long term spectral evolution of the Galactic black hole candidate Cygnus X-1 in the X-rays and at 15GHz using ~200 pointed observations taken between early 1999 and late 2004 with RXTE and the Ryle…

Astrophysics · Physics 2009-11-11 J. Wilms , M. A. Nowak , K. Pottschmidt , G. G. Pooley , S. Fritz