The 999th Swift gamma-ray burst: Some like it thermal - A multiwavelength study of GRB 151027A

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Table 2

Prompt emission time resolved spectral analysis.

Data^a	#	Start^b	Stop^b	Model^c	Γ	E_peak	A^d	kT	A_BB	χ²(d.o.f.)
		[s]	[s]			[keV]	[ph cm^-2 s^-1]	[keV]	[ph cm^-2 s^-1]

B+G	1	−0.256	1.792	CPL	0.92	207	2.93	−	−	164(244)	−
...	2	1.792	6.912	CPL	1.29	69	6.09	−	−	192(272)	−
...	3	17.152	23.296	PL	1.82	−	9.43	−	−	168(286)	−

X+B+G	4	90	100	CPL+BB	1.26	218	0.71	1.23	0.041	211(256)	3.8 × 10^-7
...	5	100	110	CPL+BB	1.06	316	0.89	3.02	0.17	279(301)	8.0 × 10^-13
...	6	110	120	CPL+BB	1.18	209	2.08	2.01	0.55	257(296)	6.3 × 10^-35
...	7	120	130	CPL+BB	1.50	76	2.71	1.12	0.51	284(293)	8.7 × 10^-45

X	8	130	140	BB	−	−	−			39(34)	−
...	9	140	150	PL+BB		−				30(26)	2.3 × 10^-6
...	10	150	160	PL+BB		−				36(46)	4.6 × 10^-10
...	11	160	170	PL		−		−	−	53(45)	(0.02)^e
...	12	170	180	PL		−		−	−	50(40)	(0.01)^e
...	13	180	190	PL		−		−	−	16(30)	−
...	14	190	200	PL		−		−	−	25(22)	−

XMM		7.8 × 10⁵	1.3 × 10⁶	PL+BB		−				398(345)	5.8 × 10^-7

Notes.

^(a)

Spectral data used in the fit: B = Swift/BAT, G = Fermi/GBM and X = Swift/XRT.

^(b)

Times refer to the trigger time of the burst.

^(c)

Models adopted in the fit: CPL = powerlaw with exponential cutoff, PL = powerlaw, BB = blackbody; galactic (N_H,gal = 3.7 × 10²⁰ cm^-2) and intrinsic (N_H = 4.4 × 10²¹ cm^-2) absorption is present in all models (using Tuebingen–Boulder ISM absorption model, Wilms et al. 2000).

^(d)

Spectral normalization is computed at 1 keV.

^(e)

In this case the addition of a BB component is not statistically significant, as suggested by the value of the null hypothesis probability associated with the F-test. The horizontal lines correspond to the differently shaded regions in Fig. 1.

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