Table 2: Best-fit parameters for the X-ray spectra of 4U 1954+31 from the pointed observations described in this paper. In all models in which a Fe emission line is needed in the fit, its width is fixed at the value $\sigma = 0.1$ keV. Frozen parameters are written between square brackets. Luminosities are not corrected for the intervening absorptions and are computed assuming a distance d = 1.7 kpc (Masetti et al. 2006a); in the cases in which the X-ray data could not completely cover the X-ray interval of interest for the luminosity determination, an extrapolation of the best-fit model is applied. Errors are at 90% confidence level for a single parameter of interest. Observations are reported in chronological order from left to right.

model: WABS*[PCFABS*WNDABS(COMPTT + GAUSS) + MEKAL]

Parametersa		 EXOSAT I EXOSAT II ROSAT RXTE BeppoSAX Swift
  (1-15 keV) (1-15 keV) (0.1-2 keV) (2.5-100 keV) (0.2-150 keV) (1.8-8.5 keV)

${\chi^{2}}$/d.o.f.		 217.7/204 86.0/85 20.0/18 112.6/105 280.1/247 53.4/44

$N_{\rm H}^{\rm WABS}$		 [1.5] [1.5] [1.5] [1.5] 1.5 +0.6-0.4 [1.5]
$N_{\rm H}^{\rm PCFABS}$ -- -- [25.4] -- 25.4 $\pm$ 1.6 1.4 +2.6-1.2
$C_{\rm PCFABS}$ (%) -- -- [95] -- 95 $\pm$ 2 [95]
$N_{\rm H}^{\rm WNDABS}$ -- -- [3.0] 4.1 +0.2-0.3 3.0 +1.3-0.7 --
$E_{\rm WNDABS}$ (keV) -- -- [1.86] [1.86] 1.86 +0.10-0.13 --
kT0 (keV) 0.56 $\pm$ 0.04 0.94 +0.05-0.06 [1.28] 1.156 +0.017-0.009 1.28 $\pm$ 0.06 0.6 +0.4-0.6
$kT_{\rm e^{-}}$ (keV) 2.86 +0.12-0.10 13 $^{+\infty}_{-9}$ [9.9] 13 +14-3 9.9 $\pm$ 0.8 8 $^{+\infty}_{-2}$
$\tau$ 9.4 +0.5-0.4 3.2 +2.5-3.2 [2.8] 2.0 +0.5-0.4 2.8 +0.3-0.2 4 +5-4
$K_{\rm COMPTT}$ ( $\times 10^{-3}$) 50 +2-3 2.1 +3.6-2.1 [8.2] 5.0 +0.4-2.4 8.2 $\pm$ 0.8 6 +120-6
$kT_{\rm MEKAL}$ ( $\times 10^{-2}$ keV) -- -- 5.3 +1.5-1.2 -- 6.8 +2.2-1.5 --
$K_{\rm MEKAL}$ -- -- 300 +5600-290 -- 200 +5400-190 --
$E_{\rm Fe}$ (keV) -- -- N/A 6.46 +0.12-0.11 6.46 +0.10-0.11 --
$I_{\rm Fe}$ ( $\times 10^{-4}$ ph cm-2 s-1) -- -- N/A 1.9 +0.5-0.4 2.5 $\pm$ 1.0 --

X-ray luminositiesb:		            
0.1-2 keV -- -- 4.1 $\times$ 1031 -- 2.0 $\times$ 1032 --
2-10 keV 1.8 $\times$ 1035 3.4 $\times$ 1034 -- 7.9 $\times$ 1034 5.2 $\times$ 1034 5.2 $\times$ 1034
10-100 keV -- -- -- 1.2 $\times$ 1035 1.8 $\times$ 1035 --
a Hydrogen column densities are in units of 1022 cm-2.
b In units of erg s-1. Values are not corrected for absorption. N/A: not applicable because of lack of spectral coverage.

Source LaTeX | All tables | In the text