Long-term evolution of Cyclotron Line energy in an eclipsing pulsar 4U 1538-522

Abstract

We present the timing and spectral analysis of the HMXB source 4U 1538-522 using NuSTAR observations. One of the observations partially covers the X-ray eclipse of the source along with eclipse ingress. The source is found to spin down at the rate of 0.163 $\pm$ 0.002 s ${\text{yr}}^{-1}$ between $\sim$ (54973-58603) MJD. It is evident that at time $\sim$ 58620 MJD, a torque reversal occurred, thereafter the source exhibited a spin-up trend at the rate - (0.305 $\pm$ 0.018) s ${\text{yr}}^{-1}$ until 59275 MJD. A recent NuSTAR observation finds the pulse period of the source: (526.2341 $\pm$ 0.0041) s. The pulse profile exhibits a transition from double-peaked to single-peaked nature above $\sim$ 30 keV. We analyzed the overall trend of the temporal evolution of fundamental Cyclotron Resonance Scattering Feature (CRSF), ${\text{E}}_{\text{cyc}}$, incorporating recent NuSTAR measurements. Initially, during the time span $\sim$ (50452.16-55270.8) MJD, the cyclotron line energy is found to increase at a rate of 0.11 $\pm$ 0.03 keV ${\text{yr}}^{-1}$ which is further followed by a decrease at a rate - 0.14 $\pm$ 0.01 keV ${\text{yr}}^{-1}$ between (55270.8-59267) MJD. The combined measurements in the time span (50452.16-59267) MJD reveal that the cyclotron line energy is increasing linearly at a rate of 0.08 $\pm$ 0.02 keV ${\text{yr}}^{-1}$.

arXiv commentAccepted for publication in MNRAS, 11 pages, 12 figures

References in corpus (46)

• Gaia Data Release 3: Summary of the content and survey properties
• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• The Fermi Gamma-Ray Burst Monitor
• Be/X-ray binaries
• Optimal binning of X-ray spectra and response matrix design
• Refined Neutron-Star Mass Determinations for Six Eclipsing X-Ray Pulsar Binaries
• Catalogue of high-mass X-ray binaries in the Galaxy ($4^{th}$ edition)
• Magnetic Fields of Accreting X-Ray Pulsars with the Rossi X-Ray Timing Explorer
• Calibration of the NuSTAR High Energy Focusing X-ray Telescope
• The critical accretion luminosity for magnetized neutron stars
• The ephemeris, orbital decay, and masses of 10 eclipsing HMXBs
• V0332+53 in the outburst of 2004--2005: luminosity dependence of the cyclotron line and pulse profile
• A model for cyclotron resonance scattering features
• NuSTAR discovery of a luminosity dependent cyclotron line energy in Vela X-1
• Timing Characteristics of the Hard X-ray Emission from Bright X-ray Pulsars Based on INTEGRAL Data
• Completing the puzzle of the 2004-2005 outburst in V0332+53: the brightening phase included
• Study of the accreting pulsar 4U 0115+634 with a bulk and thermal Comptonization model
• 4U 0115+63 from RXTE and INTEGRAL Data: Pulse Profile and Cyclotron Line Energy
• On Timing and Spectral Characteristics of the X-ray Pulsar 4U 0115+63: Evolution of the Pulsation Period and the Cyclotron Line Energy
• Luminosity dependence of the cyclotron line and evidence for the accretion regime transition in V 0332+53
• The Ups & Downs of Accreting X-Ray Pulsars: Decade-long observations with the Fermi Gamma-Ray Burst Monitor
• Outburst of GX 304-1 monitored with INTEGRAL: positive correlation between the cyclotron line energy and flux
• A 0535+26 in the August/September 2005 outburst observed by RXTE and INTEGRAL
• Phase dependent view of Cyclotron lines from model accretion mounds on Neutron Stars
• New Torque Reversal and Spin-Up of 4u 1626- 67 Observed by Fermi/GBM and Swift/BAT
• Long-term change in the cyclotron line energy in Hercules X-1
• Luminosity-dependent changes of the cyclotron line energy and spectral hardness in Cep X-4
• 4U 0115+63: phase lags and cyclotron resonant scattering
• On the spin-up/spin-down transitions in accreting X-ray binaries
• Can disk-magnetosphere interaction models and beat frequency models for quasi-periodic oscillation in accreting X-ray pulsars be reconciled?
• Discovery and Modeling of a Flattening of the Positive Cyclotron Line/Luminosity Relation in GX 304-1 with RXTE
• The BeppoSAX 0.1 - 100 keV Spectrum of the X-ray Pulsar 4U 1538-52
• The first cyclotron harmonic of 4U 1538-52
• A Clumpy Stellar Wind and Luminosity-Dependent Cyclotron Line Revealed by The First Suzaku Observation of the High-Mass X-ray Binary 4U 1538-522
• An unexpected drop in the magnetic field of the X-ray pulsar V0332+53 after the bright outburst occurred in 2015
• X-ray reprocessing: Through the eclipse spectra of high mass X-ray binaries with XMM-Newton
• Cyclotron Resonance Energies and Orbital Elements of Accretion Pulsar 4U 0115+63 During the Giant Outburst in 2008
• Measurements of Cyclotron Features and Pulse Periods in the High-Mass X-Ray Binaries 4U 1538-522 and 4U 1907+09 with INTEGRAL
• The First NuSTAR Observation of 4U 1538-522: Updated Orbital Ephemeris and A Strengthened Case for an Evolving Cyclotron Line Energy
• Timing properties of the X-ray accreting pulsar 1A 0535+262 studied with Insight-HXMT
• The cyclotron line energy in Her X-1: stable after the decay
• Recent Torque Reversal of 4U 1907+09
• Evidence for an Evolving Cyclotron Line Energy in 4U 1538-522
• Probing the Cyclotron line characteristics of 4U 1538-522 using AstroSat-LAXPC
• Variations and Correlations in Cyclotron Resonant Scattering Features of Vela X-1 Studied by INTEGRAL

Cited by in corpus (2)

• Exploring polarization and geometry in the X-ray pulsar 4U 1538-52
• On the origin of super-global spin-up trends of X-ray pulsars in HMXB systems