Discovery of two spectroscopically peculiar, low-luminosity quasars at z ∼ 4

Eilat Glikman, S. G. Djorgovski, Daniel Stern, Milan Bogosavljevic, Ashish Mahabal

    Research output: Contribution to journalArticle

    Abstract

    We report the discovery of two low-luminosity quasars at z ∼ 4, both of which show prominent N IV] λ1486 emission. This line is extremely rare in quasar spectra at any redshift; detecting it in two of a sample of 23 objects (i.e., ∼9% of the sample) is intriguing and is likely due to the low-luminosity, high-redshift quasar sample we are studying. This is still a poorly explored regime, where contributions from associated, early starbursts may be significant. One interpretation of this line posits photoionization by very massive young stars. Seeing N IV] λ1486 emission in a high-redshift quasar may thus be understood in the context of coformation and early coevolution of galaxies and their supermassive black holes. Alternatively, we may be seeing a phenomenon related to the early evolution of quasar broad emission line regions. The nondetection (and possibly even broad absorption) of N V λ1240 line in the spectrum of one of these quasars may support that interpretation. These two objects may signal a new faint quasar population or an early AGN evolutionary stage at high redshifts.

    Original languageEnglish (US)
    JournalAstrophysical Journal
    Volume663
    Issue number2 II
    DOIs
    StatePublished - Jul 10 2007

    Fingerprint

    quasars
    luminosity
    coevolution
    photoionization
    galaxies
    stars
    young

    Keywords

    • Galaxies: evolution
    • Quasars: emission lines
    • Quasars: general

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Glikman, E., Djorgovski, S. G., Stern, D., Bogosavljevic, M., & Mahabal, A. (2007). Discovery of two spectroscopically peculiar, low-luminosity quasars at z ∼ 4. Astrophysical Journal, 663(2 II). https://doi.org/10.1086/520085

    Discovery of two spectroscopically peculiar, low-luminosity quasars at z ∼ 4. / Glikman, Eilat; Djorgovski, S. G.; Stern, Daniel; Bogosavljevic, Milan; Mahabal, Ashish.

    In: Astrophysical Journal, Vol. 663, No. 2 II, 10.07.2007.

    Research output: Contribution to journalArticle

    Glikman, E, Djorgovski, SG, Stern, D, Bogosavljevic, M & Mahabal, A 2007, 'Discovery of two spectroscopically peculiar, low-luminosity quasars at z ∼ 4', Astrophysical Journal, vol. 663, no. 2 II. https://doi.org/10.1086/520085
    Glikman E, Djorgovski SG, Stern D, Bogosavljevic M, Mahabal A. Discovery of two spectroscopically peculiar, low-luminosity quasars at z ∼ 4. Astrophysical Journal. 2007 Jul 10;663(2 II). https://doi.org/10.1086/520085
    Glikman, Eilat ; Djorgovski, S. G. ; Stern, Daniel ; Bogosavljevic, Milan ; Mahabal, Ashish. / Discovery of two spectroscopically peculiar, low-luminosity quasars at z ∼ 4. In: Astrophysical Journal. 2007 ; Vol. 663, No. 2 II.
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    AB - We report the discovery of two low-luminosity quasars at z ∼ 4, both of which show prominent N IV] λ1486 emission. This line is extremely rare in quasar spectra at any redshift; detecting it in two of a sample of 23 objects (i.e., ∼9% of the sample) is intriguing and is likely due to the low-luminosity, high-redshift quasar sample we are studying. This is still a poorly explored regime, where contributions from associated, early starbursts may be significant. One interpretation of this line posits photoionization by very massive young stars. Seeing N IV] λ1486 emission in a high-redshift quasar may thus be understood in the context of coformation and early coevolution of galaxies and their supermassive black holes. Alternatively, we may be seeing a phenomenon related to the early evolution of quasar broad emission line regions. The nondetection (and possibly even broad absorption) of N V λ1240 line in the spectrum of one of these quasars may support that interpretation. These two objects may signal a new faint quasar population or an early AGN evolutionary stage at high redshifts.

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