4U 1556–60 as a very faint neutron star X-ray binary at 700 pc with an undetected radio jet

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Table 3.

NICER X-ray spectral fit of 4U 1556–60.

Model	Parameter	Value
phabs	nH (×10²²)	$0 . 34_{- 0.015}^{+ 0.016}$ $Mathematical equation: $ 0.34^{+0.016}_{-0.015} $$

bbodyrad	kT (keV)	$0 . 92_{- 0.04}^{+ 0.03}$ $Mathematical equation: $ 0.92^{+0.03}_{-0.04} $$
	norm	$9 . 12_{- 1.56}^{+ 1.75}$ $Mathematical equation: $ 9.12^{+1.75}_{-1.56} $$
	L_X (erg s⁻¹)	∼4 × 10³³
	radius (km)	0.21 ± 0.02

powerlaw	PhoIndex	$1 . 53_{- 0.04}^{+ 0.04}$ $Mathematical equation: $ 1.53^{+0.04}_{-0.04} $$
	norm	$5 . 66_{- 0.4}^{+ 0.4} \times 10^{- 2}$ $Mathematical equation: $ 5.66^{+0.4}_{-0.4} \times 10^{-2} $$

gaussian	LineE (keV)	$6 . 46_{- 0.17}^{+ 0.14}$ $Mathematical equation: $ 6.46^{+0.14}_{-0.17} $$
	Sigma (keV)	$0 . 16_{- 0.16}^{+ 0.17}$ $Mathematical equation: $ 0.16^{+0.17}_{-0.16} $$
	norm	$2 . 83_{- 0.002}^{+ 0.002} \times 10^{- 5}$ $Mathematical equation: $ 2.83^{+0.002}_{-0.002} \times 10^{-5} $$
	EqW (eV)	7.83

Chi-squared/d.o.f.	41.37/115
Flux (2–10 keV)	(erg s⁻¹ cm⁻²)	3.46 × 10⁻¹⁰
L_X (2–10 keV)	(erg s⁻¹)	1.97 × 10³⁴

Notes. Luminosities assume a distance of 700 pc. Data were fit in xspec.

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