Simultaneous observations of the blazar PKS 2155−304 from ultra-violet to TeV energies

Open Access

Table 5.

Joint NuSTAR and Swift-XRT observations of PKS 2155−304.

Epochs	PL index		LP index	LP curvature	/PHA	Flux_HT(20−40 keV) ^(b)
	Γ		Γ^(a)	β		[10⁻¹² erg cm⁻² s⁻¹]
1	2.54 ± 0.04	341.3/346		0.13 ± 0.06	332.1/346	<1.2
2	2.80 ± 0.03	414.0/340		0.27 ± 0.07	301.7/340	<0.4
3	2.77 ± 0.05	223.5/224	2.82 ± 0.07	0.09 ± 0.06	218.9/224	<0.8
4	2.71 ± 0.06	179.5/194	2.71 ± 0.06	0.00 ± 0.07	179.5/194	<0.8

7	2.72 ± 0.04	327.8/303			281.6/303	<0.5
8	2.56 ± 0.03	425.1/418	2.59 ± 0.03	0.17 ± 0.04	378.2/418	<0.8
9	2.78 ± 0.05	229.5/266	2.78 ± 0.05	0.10 ± 0.15	226.7/266	<1.3

Notes. The errors quoted on the spectral parameters as well as the quoted 20–40 keV flux limits are 90% level confidence regions. For the log-parabola model, the number of degrees of freedom is four less than the number of PHA bins, since the LP model has one extra parameter, and in addition, the normalisation of the two instruments is fitted separately. The 2–10 keV flux for joint Swift and NuSTAR spectral fits is essentially the same as that measured by NuSTAR alone.

^(a)

Γ is evaluated at 5 keV.

^(b)

The hard tail index is assumed to have Γ_HT of 2.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.