Discovery of Two Cyclotron Resonance Scattering Features in X-ray Pulsar Cen X-3 by Insight-HXMT

Abstract

We present the results of the neutron star X-ray binary system Cen X-3 performed by $Insight$-HXMT with two observations during 2017 and 2018. During these two observations, the source reached a X-ray luminosity of $\sim 10^{38}$ erg s${}^{-1}$ from 2 -- 105 keV. The analysis of the broadband X-ray spectrum reports the presence of two cyclotron resonance scattering features (CRSFs) with the fundamental line at $\sim$ 28 keV and the harmonic line at $\sim 47$ keV. The multiple lines exist by fittings with different continuum models, like the absorbed NPEX model and a power-law with high energy exponential cutoff model. This is the first time that both fundamental and harmonic lines are detected in Cen X-3. We also show evidence of two cyclotron lines in the phase-resolved spectrum of Cen X-3. The CRSF and continuum spectral parameters show evolution with the pulse profile, and the two line centroid energy ratio does not change significantly and locates in a narrow value range of $1.6-1.7$ over the pulse phase. The implications of the discovering two cyclotron absorption features and phase-resolved spectral properties are discussed.

arXiv comment8 pages, MNRAS, 2023, 519, 5402-5409

References in corpus (23)

• Observations of Accreting Pulsars
• Statistics: Handle with Care, Detecting Multiple Model Components with the Likelihood Ratio Test
• Thermal and Bulk Comptonization in Accretion-Powered X-Ray Pulsars
• Spectral Formation in Accreting X-Ray Pulsars: Bimodal Variation of the Cyclotron Energy with Luminosity
• Cyclotron lines in highly magnetized neutron stars
• The ephemeris, orbital decay, and masses of 10 eclipsing HMXBs
• A model for cyclotron resonance scattering features
• Pulse phase resolved analysis of the HMXB Cen X-3 over two binary orbits
• The variable cyclotron line in GX 301-2
• BeppoSAX observation of 4U1626-67: Discovery of an absorption cyclotron resonance feature
• A new radio census of neutron star X-ray binaries
• The first cyclotron harmonic of 4U 1538-52
• BeppoSAX observations of the X-ray pulsar MAXI J1409-619 in low state: discovery of cyclotron resonance features
• Effect of pulse profile variations on measurement of eccentricity in orbits of Cen X-3 and SMC X-1
• Discovery of a pulse-phase-transient cyclotron line in the X-ray pulsar GROJ2058+42
• Multiple cyclotron line-forming regions in GX 301-2
• Long-term evolutions of the cyclotron line energies in Her X-1, Vela X-1 and Cen X-3 as observed with Swift/BAT
• Fe KαLine in Hard X-ray Emitting Symbiotic Stars
• Relation of cyclotron resonant energy and luminosity in a strongly magnetized neutron star GRO J1008-57 observed by Insight-HXMT
• Discovery of the 5 keV cyclotron line followed by three harmonics in SwiftJ1626.6-5156
• New measurements of the cyclotron line energy in Cen X-3
• Variations of cyclotron resonant scattering features in Vela X-1 revealed with Insight-HXMT
• Timing and spectral variability of high mass X-ray pulsar GX 301--2 over orbital phases observed by Insight-HXMT

Cited by in corpus (8)

• X-ray Polarimetry of the accreting pulsar 1A~0535+262 in the supercritical state with PolarLight
• Cyclotron line formation in the radiative shock of an accreting magnetized neutron star
• An in-depth analysis of the variable cyclotron lines in GX 301$-$2
• Luminosity dependence of the multiple cyclotron lines in 4U 0115$+$63
• Revealing the state transition of Cen X-3 at high spectral resolution with Chandra
• Broadband study of the Be X-ray binary RX J0520.5-6932 during its outburst in 2024
• Studying the variations of the cyclotron line in Cen X-3 using Insight-HXMT
• Cyclotron lines in subcritical X-ray pulsars: Monte Carlo simulations reveal the origin of the observed variability