2013/02/05 by Elena Seifina, Lev Titarchuk, F. Frontera +1
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Black-body radiation #Gamma-ray bursts and supernovae #Neutron star #Optics #Photon #Physics #Pulsars and Gravitational Waves Research #Radiation #Spectral line #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/766/1/63
30 pages, 5 Tables and 12 figures, the paper has been accepted and scheduled for publication in The Astrophysical Journal, for the March 20, 2013, v 766, 1st issue
arxiv created 2013/02/05 · openalex publication_date 2013/03/07 · arxiv updated 2015/06/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We show an analysis of the spectral and timing properties of X-ray radiation from Z -source GX 340+0 during its evolution when the electron temperature of the transition layer (TL) kT e monotonically decreases from 21 to 3 keV. We analyze episodes observed with BeppoSAX and RXTE . We reveal that the X-ray broadband energy spectra during all spectral states can be reproduced by a physical model composed of a soft Blackbody component and two Comptonized components (both due to the presence of the TL that upscatters both seed photons of T s 1 ≲ 1 keV coming from the disk (first component Comptb1 ), and seed photons of temperature T s 2 ≲ 1.5 keV coming from the neutron star (second component Comptb2 ) and the iron-line ( Gaussian ) component. Spectral analysis using this model indicates that the photon power-law indices Γ com1 and Γ com2 of the Comptonized components are almost constant, Γ com1 and Γ com2 ∼ 2 when kT e changes from 3 to 21 keV along the Z -track. We interpret the detected quasi-stability of the indices of Comptonized components to be near a value of 2. Furthermore, this index stability now found for the Comptonized spectral components of Z -source GX 340+0 is similar to that previously established in the atoll sources 4U 1728-34 and GX 3+1, and earlier proposed for a number of X-ray neutron stars (NSs). This behavior of NSs both for atoll and Z -sources is essentially different from that observed in black hole binaries where Γ com increases during a spectral evolution from the low state to the high state and ultimately saturates at a high mass accretion rate.