Metals in the IGM approaching the re-ionization epoch: results from X-shooter at the VLT

被引：83

作者：

D'Odorico, V. ^{[1
]}

Cupani, G. ^{[1
]}

Cristiani, S. ^{[1
,2
]}

Maiolino, R. ^{[3
,4
,5
]}

Molaro, P. ^{[1
]}

Nonino, M. ^{[1
]}

Centurion, M. ^{[1
]}

Cimatti, A. ^{[6
]}

Alighieri, S. di Serego ^{[7
]}

Fiore, F. ^{[3
]}

Fontana, A. ^{[3
]}

Gallerani, S. ^{[8
]}

Giallongo, E. ^{[3
]}

Mannucci, F. ^{[7
]}

Marconi, A. ^{[9
]}

Pentericci, L. ^{[3
]}

Viel, M. ^{[1
,2
]}

Vladilo, G. ^{[1
]}

机构：

[1] INAF OATS, I-34143 Trieste, Italy

[2] INFN Natl Inst Nucl Phys, I-34127 Trieste, Italy

[3] INAF OAR, I-00040 Monte Porzio Catone, Italy

[4] Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England

[5] Kavli Inst Cosmol, Cambridge CB3 0HA, England

[6] Univ Bologna, Dipartimento Astron, I-40127 Bologna, Italy

[7] INAF OAArcetri, I-50125 Florence, Italy

[8] Scuola Normale Super Pisa, I-56126 Pisa, Italy

[9] Univ Florence, Dipartimento Fis & Astron, I-50019 Florence, Italy

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2013年 / 435卷 / 02期

关键词：

galaxies: abundances; intergalactic medium; quasars: absorption lines; cosmology: observations; STAR-FORMING GALAXIES; INTERGALACTIC C-IV; DIGITAL SKY SURVEY; BLACK-HOLE MASSES; LY-ALPHA FOREST; SIMILAR-TO; 6; IONIZING-RADIATION; ABSORPTION-LINES; INFRARED-SPECTRA; LYMAN FOREST;

D O I：

10.1093/mnras/stt1365

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present the results of observations taken with the X-shooter spectrograph devoted to the study of quasars at z similar to 6. This paper focuses on the properties of metals at high redshift traced, in particular, by the C IV doublet absorption systems. Six objects were observed with resolutions similar or equal to 27 and 34 km s(-1) in the visual, and 37.5 and 53.5 kms(-1) in the near-infrared. We detected 102 C IV lines in the range: 4.35 < z < 6.2 of which 27 are above z similar to 5. Thanks to the characteristics of resolution and spectral coverage of X-shooter, we could also detect 25 Si IV doublets associated with the C IV at z greater than or similar to 5. The column density distribution function of the C IV line sample is observed to evolve in redshift for z greater than or similar to 5.3, with respect to the normalization defined by low-redshift (1.5 < z < 4) C IV lines. This behaviour is reflected in the redshift evolution of the C IV cosmic mass density, Omega(C IV), of lines with column density in the range 13.4 < log N(C IV) < 15, which is consistent with a drop of a factor of similar to 2 for z greater than or similar to 5.3. Considering only the stronger C IV lines (13.8 < log N(C IV) < 15), Omega(C IV) gently rises by a factor of similar to 10 between z similar or equal to 6.2 and z similar or equal to 1.5 with a possible flattening towards z similar to 0. The increase is well fitted by a power law: Omega(C IV) = (2 +/- 1) x 10(-8)[(1 + z)/4](-3.1 +/- 0.1). An insight into the properties of the C IV absorbers and their evolution with redshift is obtained by comparing the observed column densities of associated C IV, Si IV and C II absorptions with the output of a set of CLOUDY photoionization models. As already claimed by cosmological simulations, we find that C IV is a good tracer of the metallicity in the low-density intergalactic medium (IGM) gas at z similar to 5-6 while at z similar to 3 it arises in gas with overdensity delta similar to 100.

引用

页码：1198 / 1232

页数：35