The Epoch of Major Star Formation in High-z Quasar Hosts

Taniguchi, Yoshiaki; Arimoto, N.; Murayama, Takashi; Evans, A. S.; Sanders, D. B.; Kawara, Kimiaki

doi:10.1007/978-3-540-69648-3_22

Cited by 3 publications

(1 citation statement)

References 12 publications

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“…Lípari et al 1993), such extreme Fe II emitters appear to be rare in the low-z universe. Recently, we obtained NIR spectra of two radio-loud, flat-spectrum, high-z quasars (B 1422+231 at z = 3.6 and PKS 1937−101 at z = 3.8) and found that their flux ratios of F (Fe II λλ4434-4684)/F (Hβ) are much less than those of the other high-z quasars (Kawara et al 1996;Taniguchi et al 1996Taniguchi et al , 1997, and in fact are similar to those of radio-loud, flat-spectrum, low-z quasars with normal optical Fe II emission. These new observations suggest that high-z quasars may exhibit a range of values of F (Fe II λλ4434-4684)/F (Hβ) similar to what has been observed for low-z quasars.…”

Section: Lbqs Compositementioning

confidence: 99%

Near-Infrared Spectroscopy of the High-Redshift Quasar S4 0636+68 at [CLC][ITAL]z[/ITAL][/CLC] = 3.2

Murayama

Taniguchi

Evans

et al. 1998

The Astronomical Journal

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Section: Lbqs Compositementioning

confidence: 99%

Near-Infrared Spectroscopy of the High-Redshift Quasar S4 0636+68 at [CLC][ITAL]z[/ITAL][/CLC] = 3.2

Murayama

Taniguchi

Evans

et al. 1998

The Astronomical Journal

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New Near-Infrared Spectroscopy of the High-Redshift Quasar B1422+231 at [CLC][ITAL]z[/ITAL][/CLC] = 3.62

Murayama

Taniguchi

Evans

et al. 1999

The Astronomical Journal

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We present new near-infrared (rest-frame UV-to-optical) spectra of the high-redshift, gravitationally lensed quasar B1422]231 (z \ 3.62). Diagnostic emission lines of Fe II, O III j5007, and Hb, commonly used to determine the excitation, ionization, and chemical abundances of radio-quiet and radio-loud quasars, were detected. Our new data show that the ratio Fe II (UV)/Hb \ 18.1^4.6 and Fe II (optical)/ Hb \ 2.3^0.6 are higher than those reported by Kawara et al. by factors of 1.6 and 3.3, respectively, although the ratio [O III] j5007/Hb \ 0.19^0.02 is nearly the same between the two measurements. The discrepancy of the line Ñux ratios between the measurements is likely due to improved data and Ðtting procedures rather that to intrinsic variability. While approximately half of the high-z quasars observed to date have much more extreme Fe II (optical)/Hb ratios, the line ratio measured for B1422]231 are consistent with the observed range of Fe II (optical) ratios of low-z quasars.

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Elemental Abundances in Quasistellar Objects: Star Formation and Galactic Nuclear Evolution at High Redshifts

Hamann

Ferland

1999

Annu. Rev. Astron. Astrophys.

384

364

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Quasar (or QSO) elemental abundances provide unique probes of highredshift star formation and galaxy evolution. There is growing evidence from both the emission and intrinsic absorption lines that QSO environments have roughly solar or higher metallicities out to redshifts >4. The range is not well known, but solar to a few times solar appears to be typical. There is also evidence for higher metallicities in more luminous objects, and for generally enhanced N/C and Fe/α abundances compared to solar ratios.These results identify QSOs with vigorous, high-redshift star formation -consistent with the early evolution of massive galactic nuclei or dense proto-galactic clumps. However, the QSOs offer new constraints. For example, 1) most of the enrichment and star formation must occur before the QSOs "turn on" or become observable, on time scales of ∼ <1 Gyr at least at the highest redshifts. 2) The tentative result for enhanced Fe/α suggests that the first local star formation began at least ∼1 Gyr prior to the QSO epoch.3) The star formation must ultimately be extensive in order to reach high metallicities, i.e. a substantial fraction of the local gas must be converted into stars and stellar remnants. The exact fraction depends on the shape of the initial mass function (IMF). 4) The highest derived metallicities require IMFs that are weighted slightly more toward massive stars than the in solar neighborhood. 5) High metallicities also require deep gravitational potentials. By analogy with the well-known mass-metallicity relation among low-redshift galaxies, metal-rich QSOs should reside in galaxies (or proto-galaxies) that are minimally as massive (or as tightly bound) as our own Milky Way. 5 Enrichment Scenarios 31 5.

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The Epoch of Major Star Formation in High-z Quasar Hosts

Cited by 3 publications

References 12 publications

Near-Infrared Spectroscopy of the High-Redshift Quasar S4 0636+68 at [CLC][ITAL]z[/ITAL][/CLC] = 3.2

Near-Infrared Spectroscopy of the High-Redshift Quasar S4 0636+68 at [CLC][ITAL]z[/ITAL][/CLC] = 3.2

New Near-Infrared Spectroscopy of the High-Redshift Quasar B1422+231 at [CLC][ITAL]z[/ITAL][/CLC] = 3.62

Elemental Abundances in Quasistellar Objects: Star Formation and Galactic Nuclear Evolution at High Redshifts

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