Table 1.
Parameters obtained for the fit of the Fermi-LAT energy spectrum of PKS 0447−439 using power law (PL), log parabola (LP), broken power law (BPL) and PLSuperExpCutOff (PLSEC) spectral models.
| Model | Energy | Spectral parameters | Npred. | Integral flux | TS | Log- | Log-likelihood |
|---|---|---|---|---|---|---|---|
| [GeV] | 10−8[cm−2 s−1] | likelihood | ratio-test | ||||
| Power law (PL) | 0.1 … 500 | Γ = 1.867 ± 0.009 | 16724 | (7.83 ± 0.13) | 29293 | −402489.3 | − |
| Log parabola | 0.1 … 500 | Γα = 1.742 ± 0.025 | 15726 | (7.39 ± 0.15) | 29234 | −402479.8 | 19.00 |
| (LP) | Γβ = 0.020 ± 0.004 | (4.4σ) | |||||
| Broken power law | 0.1 … 500 | Γ1 = 1.839 ± 0.009 | 16234 | (7.62 ± 0.13) | 29305 | −402462.4 | 53.80 |
| (BPL) | Γ2 = 2.825 ± 0.171 | (7.3σ) | |||||
| Eb = 42.84 ± 1.78 | |||||||
| PLSuperExpCutOff | 0.1 … 500 | Γ1 = 1.818 ± 0.012 | 16119 | (7.51 ± 0.14) | 29282 | −402464.2 | 50.20 |
| Γ2 = 1.031 ± 0.195 | (7.1σ) | ||||||
| Ec = 137.9 ± 24.3 | |||||||
Notes. The last column gives the significance, obtained using Log-likelihood test by comparing the log-likelihood values for each model against those for the power-law model. Only statistical errors are shown. A BPL is preferred here. Npred. represents the number of predicted photons.
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