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Table 2.

Spectral model parameters for the five point sources and the diffuse emission in ESO 338-4.

Model parameter Best-fit value
Point sources

ULX1: tbabsGal × tbabsint × (diskbb1 + diskbb2)

NH, int (1022 cm−2) 0.6 ± 0.3
Tin, 1 (keV) 1.7 ± 0.2
Norm1 (8 ± 3)×10−4
Tin, 2 (keV) 0.215 ± 0.009
Norm2 30 ± 10

ULX2: tbabsGal × tbabsint × diskpbb

NH, int (1022 cm−2) 0.1 ± 0.2
Tin (keV) 1.2 ± 0.1
Norm (7 ± 9)×10−3
Γ 1.0 ± 0.8

ULX3: tbabsGal × tbabsint × powerlaw

NH, int (1022 cm−2) 0.7 ± 0.3
Norm (photons keV−1 cm−2 s−1 at 1 keV) (1.8 ± 0.8)×10−5
Γ 2.7 ± 0.3

ULX4: tbabsGal × tbabsint × powerlaw

NH, int (1022 cm−2) 0.9 ± 0.6
Norm (photons keV−1 cm−2 s−1 at 1 keV) (1.0 ± 0.7)×10−5
Γ (2.5 ± 0.6)

ULX5: tbabsGal × tbabsint × powerlaw

NH, int (1022 cm−2) 2.1 ± 0.8
Norm (photons keV−1 cm−2 s−1 at 1 keV) (1.6 ± 1.2)×10−6
Γ 2.5 ± 0.6

Diffuse sources

Halo: tbabsGal × (APEC1 + APEC2)

kT1 (keV) 0.26 ± 0.02
Norm1 (cm−3) (2.7 ± 0.4)×10−5
kT2 (keV) 3.5 ± 0.3
Norm2 (cm−3) (6.1 ± 0.2)×10−5

Central: tbabsGal × (APEC + Point-source contribution)

kT (keV) 0.262 ± 0.007
Norm (cm−3) (3.7 ± 0.1)×10−4

Notes. The results were derived by fitting the spectra of the Chandra and XMM-Newton observations of Appendix A. The Galactic foreground absorption tbabsGal is fixed at the value of NH = 5 × 1020 cm−2.

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