Hard X-ray emission of the luminous infrared galaxy NGC 6240 as observed by NuSTAR

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Table 4

Chandra best-fit parameters for the two nuclei.

Parameter	S^a	N^b	Units

Γ ^c	1.75	1.75
N _H ^d	1.57	1.91	10²⁴ cm^-2
A _Z ^e	106	41	10⁴ ph keV^-1 cm^-2 s^-1
Θ ^f	80	73	deg
FeK_αEW^g	0.37	0.58	keV
χ²/d.o.f.	135.2/ 112	90.75/68
/χ² prob.	1.2/6.7%	1.34/3.4%
L_{A_Z}^h (2−10 keV)	5.2	2.0	10⁴³ erg s^-1
L_{A_Z}ⁱ (10−40 keV)	7.1	2.7	10⁴³ erg s^-1
L_{A_Z}ⁱ (2−78 keV)	15.7	6.0	10⁴³ erg s^-1
L_{A_S}ⁱ (10−40 keV)	1.2	0.5	10⁴³ erg s^-1

Notes. Chandra best-fit values with uncertainties at the 90% confidence level for one parameter of interest (Δχ² = 2.706).

^(a)

Best-fit parameters for the southern nucleus;

^(b)

best-fit parameters for the northern nucleus;

^(c)

direct power-law photon index fixed to the best-fit value of the total spectrum (see Sect. 4.2);

^(d)

equatorial column density N_H;

^(e)

normalization of the primary continuum referred to 1 keV;

^(f)

inclination angle between the torus polar axis and the observer’s line of sight;

^(g)

line equivalent width;

^(h)

intrinsic primary 2−10 keV luminosities;

⁽ⁱ⁾

intrinsic 10−40 keV and 2−78 keV luminosities evaluated extrapolating the Chandra best-fit model using the NuSTAR response efficiency: L_{A_Z} for the primary continuum, L_{A_S} for the reflected/scattered component.

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