2009A&A...503..721M


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.13CEST23:07:07

2009A&A...503..721M - Astronomy and Astrophysics, volume 503, 721-730 (2009/9-1)

Chemical evolution of high-redshift radio galaxies.

MATSUOKA K., NAGAO T., MAIOLINO R., MARCONI A. and TANIGUCHI Y.

Abstract (from CDS):

We present new deep optical spectra of 9 high-z radio galaxies (HzRGs) at z>2.7 obtained with FORS2 on VLT. These rest-frame ultraviolet spectra are used to infer the metallicity of the narrow-line regions (NLRs) in order to investigate the chemical evolution of galaxies in the high-z universe. We focus mainly on the CIV/HeII and CIII]/CIV flux ratios that are sensitive to both the gas metallicity and ionization parameter. Although the NV emission has been widely used to infer the gas metallicity, it is often too weak to be measured accurately for NLRs. In combining our new spectra with data from the literature, we examine the possible redshift evolution of the NLR metallicity for 57 HzRGs at 1≲z≲4. Based on the comparison between the observed emission-line flux ratios and the results of our photoionization model calculations, we find no significant metallicity evolution in NLRs of HzRGs, up to z∼4. Our results imply that massive galaxies had almost completed their chemical evolution at much higher redshift (z>5). Finally, although we detect strong NV emission lines in 5 HzRGs at z>2.7, we point out that high NV/HeII ratios are not indicative of high metallicities but correspond to high ionization parameters of gas clouds in NLRs.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: evolution - galaxies: nuclei - quasars: emission lines - quasars: general

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NVSS J012142+132058 Rad 01 21 42.69 +13 20 58.1           ~ 34 0
2 NVSS J020510+224250 Rad 02 05 10.61 +22 42 49.7           ~ 26 1
3 NVSS J031812-253509 rG 03 18 12.00 -25 35 09.0   23.6 23.8     ~ 73 2
4 PMN J0419-1801 rG 04 19 43.7 -18 01 55           ~ 18 1
5 NVSS J092022-071217 rG 09 20 22.40 -07 12 17.0       22.4   ~ 14 0
6 B2 1121+31 B Rad 11 23 55.85 +31 41 26.1           ~ 19 0
7 4C 24.28 rG 13 48 14.890 +24 15 50.34     17.7     ~ 44 1
8 NVSS J154817-233701 rG 15 48 17.5 -23 37 05           ~ 18 1
9 NVSS J220514+130533 rG 22 05 14.36 +13 05 32.5           ~ 23 1

    Equat.    Gal    SGal    Ecl

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2020.07.13-23:07:07

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