VLT/X-Shooter spectroscopy of the afterglow of the Swift GRB 130606A - Chemical abundances and reionisation at z ~ 6

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Volume 580 (August 2015)

A&A, 580 (2015) A139

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Table 3

Derived column densities from the host galaxy absorption lines.

Low-ionisation or neutral species
Ion	log N₂	log N₄	log N₅	log N_tot	[X/H]

H i				19.91 ± 0.02
C ii	13.79 ± 0.14	>15.00^a	13.83 ± 0.10	>15.04	[ C/H ] > −1.26 ^a
C ii*	13.40 ± 0.15	13.70 ± 0.09	13.38 ± 0.11	14.01 ± 0.06
O i	–	14.87 ± 0.12	–	>14.75	[ O/H ] > −1.85 ^c
Al ii	–	12.72 ± 0.22	14.63 ± 0.83	14.66 ± 0.78	[ Al/H ] = + 0.31 ± 0.78 ^d
Al iii	12.28 ± 0.54	12.98 ± 0.14	13.75 ± 0.23	13.85 ± 0.19
Si ii	12.73 ± 0.13	13.73 ± 0.15	13.42 ± 0.18	13.95 ± 0.11	[ Si/H ] = −1.30 ± 0.08 ^b
Si ii*	12.55 ± 0.16	13.28 ± 0.07	13.26 ± 0.11	13.62 ± 0.06
S ii	13.55 ± 0.31	12.95 ± 1.04	13.02 ± 0.74	<14.44^e	[ S/H ] < −0.60
Fe ii	–	13.09 ± 0.05	12.82 ± 0.17	13.29 ± 0.07	[ Fe/H ] = −2.09 ± 0.08
Fe ii*	<11.80	<11.80	<11.80	<12.10
Ni ii	–	<13.83	<13.91	<14.22	[ Ni/H ] < + 0.16 ^b
Ni ii*	<12.92	<12.90	<13.14	<13.45

High-ionisation species
Ion	log N₁	log N₃	log N₆	log N_tot

N v	13.79 ± 0.06	14.04 ± 0.09	14.33 ± 0.04	14.59 ± 0.03

Notes. The redshift and b parameters of the components for low- and high-ionisation species are listed in Table 2. Column densities are given as log (N/ cm^-2).

^(a)

This component is most likely saturated; we obtain a minimum log N from the equivalent width of the component.

^(b)

Based on the sum of the ground state and excited state.

^(c)

Lower limit because both component 5 and the excited state column density cannot be measured due to telluric contamination.

^(d)

Based only on Al ii. The sum of Al ii and Al iii results in [ Al/H ] = + 0.46 ± 0.62.

^(e)

1σ upper limit because the relative strength of the components does not resemble the clearly detected lines, which means that we are measuring the noise.

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