J/MNRAS/435/1198 z∼6 QSOs CIV doublet absorption systems (D'Odorico+, 2013)
Metals in the IGM approaching the re-ionization epoch:
results from X-shooter at the VLT.
D'Odorico V., Cupani G., Cristiani S., Maiolino R., Molaro P., Nonino M.,
Centurion M., Cimatti A., Di Serego Alighieri S., Fiore F., Fontana A.,
Gallerani S., Giallongo E., Mannucci F., Marconi A., Pentericci L.,
Viel M., Vladilo G.
<Mon. Not. R. Astron. Soc., 435, 1198-1232 (2013)>
=2013MNRAS.435.1198D 2013MNRAS.435.1198D
ADC_Keywords: QSOs ; Spectroscopy
Keywords: galaxies: abundances - intergalactic medium -
quasars: absorption lines - cosmology: observations
Abstract:
We present the results of observations taken with the X-shooter
spectrograph devoted to the study of quasars at z∼6. This paper
focuses on the properties of metals at high redshift traced, in
particular, by the CIV doublet absorption systems. Six objects were
observed with resolutions ≃27 and 34km/s in the visual, and 37.5 and
53.5km/s in the near-infrared. We detected 102 CIV lines in the
range: 4.35<z<6.2 of which 27 are above z∼5. Thanks to the
characteristics of resolution and spectral coverage of X-shooter, we
could also detect 25 SiIV doublets associated with the CIV at z≳5.
The column density distribution function of the CIV line sample is
observed to evolve in redshift for z≳5.3, with respect to the
normalization defined by low-redshift (1.5<z<4) CIV lines. This
behaviour is reflected in the redshift evolution of the CIV cosmic
mass density, ΩCIV, of lines with column density in the range
13.4<logN(CIV)<15, which is consistent with a drop of a factor of ∼2
for z≳5.3. Considering only the stronger CIV lines
(13.8<logN(CIV)<15), ΩCIV gently rises by a factor of ∼10
between z≃6.2 and z≃1.5 with a possible flattening towards z∼0. The
increase is well fitted by a power law:
Ω_CIV=(2±1)x10-8[(1+z)/4]-3.1±0.1. An insight into the
properties of the CIV absorbers and their evolution with redshift is
obtained by comparing the observed column densities of associated CIV,
SiIV and CII absorptions with the output of a set of cloudy
photoionization models. As already claimed by cosmological
simulations, we find that CIV is a good tracer of the metallicity in
the low-density intergalactic medium (IGM) gas at z∼5-6 while at z∼3
it arises in gas with overdensity δ∼100.
Description:
We present the spectra obtained in a Guaranteed Timed Observation
(GTO) programme (PI: V. D'Odorico) carried out with the X-shooter
spectrograph at the European Southern Observatory (ESO) Very Large
Telescope (VLT) between 2010 January and 2011 June.
The spectra were acquired with a binning of two pixels in the
dispersion direction and adopting two sets of slit apertures for the
blue, visual (VIS) and near-infrared (NIR) arms, respectively:
1.0/0.9/0.9 and 0.8/0.7/0.6 arcsec depending on the seeing conditions
at the moment of the observations.
Objects:
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RA (ICRS) DE Designation(s) (files)
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08 18 27.4 +17 22 52 SDSS J0818+1722 = QSO J0818+1722 (tablea1.dat)
08 36 43.9 +00 54 53 SDSS J0836+0054 = QSO J0836+0054 (tablea2.dat)
10 30 27.09 +05 24 55.1 SDSS J1030+0524 = QSO J1030+0524 (tablea3.dat)
13 06 08.2 +03 56 26 SDSS J1306+0356 = QSO J1306+0356 (tablea4.dat)
13 19 11.28 +09 50 51.4 SDSS J1319+0950 = QSO J1319+0950 (tablea5.dat)
15 09 41.8 -17 49 27 CFHQS J1509-1749 = QSO J1509-1749 (tablea6.dat)
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 72 6 X-shooter spectroscopic observations
tablea1.dat 68 62 CIV absorption systems in SDSS J0818+1722
tablea2.dat 68 47 CIV absorption systems in SDSS J0836+0054
tablea3.dat 68 45 CIV absorption systems in SDSS J1030+0524
tablea4.dat 68 44 CIV absorption systems in SDSS J1306+0356
tablea5.dat 68 46 CIV absorption systems in ULAS J1319+0950
tablea6.dat 68 21 CIV absorption systems in CFHQS J1509-1749
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- QSO Quasar name
13- 17 F5.3 --- zem [5.8/6.4] Redshift of emission lines
19- 23 F5.2 mag Jmag [17/19] J-band (near-IR) magnitude
25- 29 I5 s Tvis Exposure time in visible (optical)
31- 35 I5 s Tnir Exposure time in near-infrared
37- 39 I3 --- SNRv [50/125] Signal-to-noise ratio at 0.9µm
41- 42 I2 --- SNRi [7/24] Signal-to-noise ratio at 1.035µm
44- 48 F5.3 --- zC.min Lower value of CIV absoption redshift
49 A1 --- --- [-]
50- 54 F5.3 --- zC.max Upper value of CIV absoption redshift
56- 60 F5.3 --- DX CIV redshift absorption path ΔXCIV
62- 66 F5.3 --- zSi.min Lower value of SiIV absoption redshift
67 A1 --- --- [-]
68- 72 F5.3 --- zSi.max Upper value of SiIV absoption redshift
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Byte-by-byte Description of file: tablea?.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Sys [1/22] System number (in QSO)
3 A1 -- m_Sys [abcdefghi] Multiplicity index on System
5- 13 A9 --- Ion Ion (CII, CIV, or SiIV)
14- 15 A2 --- n_Ion [asbmlS ] Note on line (1)
17- 23 F7.5 --- z [4.4/6.0]? Redshift
25- 31 F7.5 --- e_z ? rms uncertainty on z
33 A1 --- l_W0 Limit flag on W0
34- 39 F6.3 0.1nm W0 [0/1.6]? Rest-frame equivalent width (Å)
41- 45 F5.3 0.1nm e_W0 ? rms uncertainty on W0
48- 51 F4.1 km/s b [7/94]? Doppler velocity width
53- 56 F4.1 km/s e_b ? rms uncertainty on b
58 A1 --- l_logN Limit flag on logN
59- 63 F5.2 [cm-2] logN [12/14.6]? Abundance (column density)
65- 68 F4.2 [cm-2] e_logN ? rms uncertainty on logN
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Note (1): Notes as follows:
b = line blended with another absorption line
m = multiple components
s = line contaminated by a sky emission line
l = feature below 3σ detection.
a = We found an alternative identification for this line:
it could be AlIII at zabs~=3.71
S = The line could be saturated
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Jan-2015