Spectral evolution of X-ray pulsar 4U 1901+03 during the 2019 outburst based on Insight-HXMT and NuSTAR observations

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Table 2.

Best-fit parameters for the model TBABS × (GAU+CUTOFFPL × GABS) for the four data sets of pulse-averaged spectra during the 2019 outburst.

Model	Parameters	Units	NuObs1	NuObs2	NuObs3	NuObs4
					+P0211006008	+P0211006022
CONSTANT^(a)	FPMB/FPMA		0.996	1.026±0.001	1.028	1.017
CONSTANT^(b)	LE/FPMA				0.987	0.930
CONSTANT^(c)	ME/FPMA				1.004	0.983
TBABS	N_H	10²² cm⁻²	2.3	2.9	2.31	2.57
CUTOFFPL	Γ		0.50	0.52	0.38	0.58
	E_cut	keV	7.42	7.00	6.39	6.94
	A_PL		0.314	0.40	0.211	0.217
GABS	E_abs1	keV	10.95	11.55	10.21	8.3
	σ_abs1	keV	3.6	2.2	3.6	5.4
	τ_abs1		0.17	0.10	0.23	0.49
GAUSSIAN	E_Fe	keV	6.55	6.54	6.58	6.59
	σ_Fe	keV	0.30	0.38	0.26	0.17
	A_Fe	10⁻³ ph s⁻¹ cm⁻²	3.3	5.38	2.1	1.13

F_1−79 keV^(d)		10⁻⁹ erg s⁻¹ cm⁻²	8.26	9.78	5.41	3.40
F_4−79 keV^(d)		10⁻⁹ erg s⁻¹ cm⁻²	6.62	7.70	4.270	2.610
χ²(d.o.f.)			2102 (1668)	1720 (1568)	3081 (2954)	3522 (3090)

Notes.

^(a)

Cross-normalisation constant between FPMB and FMPA instruments on board NuSTAR.

^(b)

Cross-normalisation constant between Insight-HXMT/LE and NuSTAR/FPMA instruments.

^(c)

Cross-normalisation constant between Insight-HXMT/ME and NuSTAR/FPMA instruments.

^(d)

Unabsorbed X-ray flux.

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