Open AccessX‐ray spectral evolution of low‐mass X‐ray binary GX 349+2
Author(s) -
Agrawal V. K.,
Sreekumar P.
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2003.07147.x
Subject(s) - physics , astrophysics , black body radiation , spectral line , proportional counter , accretion (finance) , binary number , x ray binary , diagram , line (geometry) , astronomy , optics , neutron star , geometry , statistics , arithmetic , mathematics , detector , radiation
We present the results of a systematic investigation of spectral evolution in the Z source GX 349+2, using data obtained during 1998 with the Proportional Counter Array (PCA) on‐board the RXTE satellite. The source traced a extended normal branch (NB) and flaring branch (FB) in the colour–colour diagram (CD) and the hardness‐intensity diagram (HID) during these observations. The spectra at different positions of the Z‐track were best fitted by a model consisting of a disc blackbody and a Comptonized spectrum. A broad (Gaussian) iron line at ∼6.7 keV is also required to improve the fit. The spectral parameters showed a systematic and significant variation with the position along the Z‐track. The evolution in spectral parameters is discussed in view of the increasing mass accretion rate scenario, proposed to explain the motion of Z sources in the CD and the HID.