Effective area calibration of the reflection grating spectrometers of XMM-Newton - I. X-ray spectroscopy of the Crab nebula

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Volume 497 / No 1 (April I 2009)

A&A, 497 1 (2009) 291-310

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Table 2:

Best fit parameters.
Parameter^a	Model A	Model B	Model C
	pure gas	gas & dust	pure gas
	curv. corr.	curv. corr	no curv. corr
$\chi^2$	2341	2327	2366
d.o.f.	1316	1315	1316
f(5)^b	$1.056\pm 0.009$	$1.055\pm 0.009$	$1.035\pm 0.009$
f(40)^b	$0.746\pm 0.016$	$0.762\pm 0.016$	$0.854\pm 0.019$
column densities^c:
H I^d,e	$31~750\pm 220$	$9700 \pm 1700$	$31~280\pm 220$
H I^d,f	-	$22~300 \pm 1800$	-
H I^d,g	$31~750\pm 220$	$32~060\pm 220$	$31~280\pm 220$
H II^h	$1752\pm 4$	$1752\pm 4$	$1752\pm 4$
N I	$2.67\pm 0.24$	$2.72\pm 0.24$	$2.48\pm 0.25$
O I	$19.28\pm 0.18$	$19.83\pm 0.22$	$19.23\pm 0.18$
O II	$0.23\pm 0.14$	$0.25\pm 0.15$	$0.20\pm 0.14$
Ne I	$4.69\pm 0.21$	$4.66\pm 0.21$	$4.74\pm 0.21$
Ne II	$0.46\pm 0.25$	$0.52\pm 0.24$	$0.64\pm 0.25$
Mg I	$1.14\pm 0.28$	$1.20\pm 0.28$	$1.13\pm 0.28$
Mg II	$0.00\pm 0.09$	$0.00\pm 0.10$	$0.00\pm 0.09$
Fe I	$0.65\pm 0.05$	$0.77\pm 0.04$	$0.65\pm 0.05$
Fe II	$0.23\pm 0.06$	$0.14\pm 0.04$	$0.26\pm 0.07$

^a Error bars are all $1\sigma$ for one interesting parameter.
^b f(5) and f(40) are the values of the effective area scale factor $f(\lambda)$ , Eq. (5), at 5 and 40 Å.
^c Ionic column densities are given in units of 10²¹ m^-2. The column densities of all metals include all phases (dust and gas).
^d H I includes in the cross section contributions from neutral He, C, Si, S, Ar, Ca and Ni assuming proto-solar abundances for these elements.
^e For the pure gaseous phase only.
^f For the gas & dust mixture with proto-solar abundances added to the pure gaseous phase above.
^g Total column: sum of contributions listed as b and c.
^h For H II the column is derived from the pulsar dispersion measure assuming that all free electrons originate from hydrogen (see text).

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