Chemical Evolution of High-Redshift Radio Galaxies

Details Chemical Evolution of High-Redshift Radio Galaxies Chemical Evolution of High-Redshift Radio Galaxies

2009-05-11

arxiv.org/abs/0905.1581v1

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

11 pages, 12 figures, to appear in Astronomy & Astrophysics

Scientific paper

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 high-z universe. We focus mainly on the CIV/HeII and CIII]/CIV flux ratios that are sensitive to 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. By 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.

Affiliated with

Also associated with

No associations

Rating

Chemical Evolution of High-Redshift Radio Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Chemical Evolution of High-Redshift Radio Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chemical Evolution of High-Redshift Radio Galaxies will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-701186