Giant outburst of EXO 2030+375: pulse-phase resolved analysis of INTEGRAL data

Abstract

In June-September 2006 the Be/X-ray binary EXO 2030+375 experienced the second giant outburst since its discovery. The source was shown to have a complicated pulse-averaged X-ray spectral continuum with possible evidence of cyclotron absorption features. In this paper we present the first pulse-phase resolved analysis of the broad band X-ray spectra of EXO 2030+375 obtained with the INTEGRAL observatory close to the maximum and during the decay phase of the giant outburst. We report a strong variability of the spectrum with pulse phase. Alternative spectral continuum models are discussed. The dependence of the spectral parameters on pulse phase during the maximum of the outburst and the evolution of the pulse profiles with time are qualitatively consistent with the pulsar's emission diagram changing from the fan-beam geometry close to the maximum of the outburst to a combination of pencil and fan beams (of comparable intesities) at the end of the decay phase. Evidence of a cyclotron absorption line around 63 keV at the pulse phase interval preceeding the main peak of the pulse profile is present in the spectrum obtained close to the maximum of the outburst.

8 pages, 10 figures, accepted for publication in A&A

References in corpus (6)

• Discovery of a flux-related change of the cyclotron line energy in Her X-1
• Outbursts Large and Small from EXO 2030+375
• INTEGRAL observations of Her X-1
• INTEGRAL observation of the accreting pulsar GX 1+4
• INTEGRAL and Swift observations of EXO 2030+375 during a giant outburst
• INTEGRAL observations of the Crab pulsar

Cited by in corpus (19)

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• Decade long RXTE monitoring observations of Be/X-ray binary pulsar EXO 2030+375
• Timing and Spectral properties of Be/X-ray pulsar EXO 2030+375 during a Type I outburst
• A polarimetrically oriented X-ray stare at the accreting pulsar EXO 2030+375
• Observations of 4U 1626-67 with the Imaging X-ray Polarimetry Explorer
• Possible regular phenomena in EXO 2030+375
• Studying the accretion geometry of EXO 2030+375 at luminosities close to the propeller regime
• Glancing through the accretion column of EXO 2030+375
• Dynamical Effects of Magnetic Opacity in Neutron Star Accretion Columns
• Average bolometric corrections and optical to X-ray flux measurements as a function of accretion rate for X-ray binaries
• Suzaku Observation of Be/X-ray Binary Pulsar EXO 2030+375
• Timing analysis of EXO 2030+375 during its 2021 giant outburst observed with Insight-HXMT
• Spectral & Timing analysis of Be/X-ray binary EXO 2030+375 during its giant 2021 outburst
• X-ray emission evolution of the Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124 during the 2017-2018 outburst observed by the MAXI GSC
• The giant outburst of EXO 2030+375 I: Spectral and pulse profile evolution
• The unaltered pulsar: GRO J1750-27, a super-critical X-ray neutron star that does not blink an eye
• Phase dependent evolution within large luminosity range of 1A 0535+262 observed by Insight-HXMT during 2020 giant outburst
• Timing and spectral studies of Cen X-3 in multiple luminosity states using $\text{AstroSat}$
• First characterization of a new High Mass X-ray Binary in LMC eRASSU J050810.4$-$660653 with SRG/ART-XC, NuSTAR and Swift