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The luminosity dependence of the X-ray spectrum of the transient 42 second pulsar EXO 2030 + 375

1993; IOP Publishing; Volume: 414; Linguagem: Inglês

10.1086/173076

1538-4357

A. P. Reynolds, A. N. Parmar, N. E. White,

Pulsars and Gravitational Waves Research

view Abstract Citations (35) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Luminosity Dependence of the X-Ray Spectrum of the Transient 42 Second Pulsar EXO 2030+375 Reynolds, A. P. ; Parmar, A. N. ; White, N. E. Abstract We report on the evolution in the X-ray spectrum of the transient X-ray pulsar EXO 2030 + 375 during part of an outburst in 1985 May-August. The overall continuum spectral shape is similar to that of other accreting pulsars and can be represented by a power-law spectrum modified at low energies by significant absorption and at high energies either by an exponential cutoff or by the effects of cyclotron scattering. As the luminosity decreased by a factor of about 100, the X-ray spectrum became harder with the photon index decreasing from 1.83 +/- 0.01 to 1.29 +/- 0.01. In addition, the high-energy cutoff energy decreased from 20 to 10 keV during the same interval. If the cutoff is interpreted in terms of cyclotron resonance scattering, then this variation implies a magnetic field strength that decreased from 2.6 x 10 exp 12 to 1.3 x 10 exp 12. This variation implies that the cutoff energy does not provide a reliable measure of the surface magnetic field strength in this system. Publication: The Astrophysical Journal Pub Date: September 1993 DOI: 10.1086/173076 Bibcode: 1993ApJ...414..302R Keywords: Neutron Stars; Pulsars; Stellar Luminosity; X Ray Spectra; X Ray Stars; Cyclotron Resonance; Energy Spectra; Magnetic Field Configurations; Astrophysics; STARS: NEUTRON; STARS: PULSARS: INDIVIDUAL ALPHANUMERIC: EXO 2030; 375; X-RAYS: STARS full text sources ADS | data products SIMBAD (6)