We report the preliminary results of a 350 ks BeppoSAX observation of the bright atoll source GX 9 + 1. In the field of view of the MECS instrument we discovered a X-ray pulsar, designated SAX J1802.7-2017, at an angular distance from GX 9+1 of similar to 22'. Since the X-ray emission of SAX J1802.7-2017 contaminates the energy spectrum above 10 keV we studied the energy spectrum of GX 9 + 1 in the energy band 0.1 - 10 keV. We selected four regions in the color-color diagram and extracted one spectrum from each region. A bump below 1 keV is present in the spectra using a model composed by a Comptonized component absorbed by neutral matter having an equivalent hydrogen column of 1.5 x 10(22) cm(-2). The bump disappears adding an overabundance of iron and nickel of 7 and 70 with respect to the solar iron abundance and to the solar nickel abundance, moreover the equivalent hydrogen column becames 0.5 x 10(22) cm(-2) suggesting a possible distance to the source of 4.5 kpc, implying a luminosity of 4 x 10(37) erg s(-1) and that the bright atoll source GX 9 + 1 is not bright but it is a typical atoll source.
A preliminary BeppoSAX study of the (Bright) atoll source GX 9+1
BURDERI, LUCIANO;
2003-01-01
Abstract
We report the preliminary results of a 350 ks BeppoSAX observation of the bright atoll source GX 9 + 1. In the field of view of the MECS instrument we discovered a X-ray pulsar, designated SAX J1802.7-2017, at an angular distance from GX 9+1 of similar to 22'. Since the X-ray emission of SAX J1802.7-2017 contaminates the energy spectrum above 10 keV we studied the energy spectrum of GX 9 + 1 in the energy band 0.1 - 10 keV. We selected four regions in the color-color diagram and extracted one spectrum from each region. A bump below 1 keV is present in the spectra using a model composed by a Comptonized component absorbed by neutral matter having an equivalent hydrogen column of 1.5 x 10(22) cm(-2). The bump disappears adding an overabundance of iron and nickel of 7 and 70 with respect to the solar iron abundance and to the solar nickel abundance, moreover the equivalent hydrogen column becames 0.5 x 10(22) cm(-2) suggesting a possible distance to the source of 4.5 kpc, implying a luminosity of 4 x 10(37) erg s(-1) and that the bright atoll source GX 9 + 1 is not bright but it is a typical atoll source.
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