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    A FIRST–APM–SDSS survey for high-redshift radio QSOs

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    Identificadores
    URI: http://hdl.handle.net/10902/1890
    DOI: 10.1111/j.1365-2966.2006.10543.x
    ISSN: 1365-2966
    ISSN: 0035-8711
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    Author
    Carballo Fidalgo, RuthAutoridad Unican; González Serrano, José IgnacioAutoridad Unican; Montenegro-Montes, Francisco M.; Benn, Chris R.; Mack, Karl Heinz; Pedani, Marco; Vigotti, Mario
    Date
    2006-08
    Derechos
    © 2006 The Authors. Journal compilation © 2006 RAS
    Publicado en
    Monthly Notices of the Royal Astronomical Society, 2006, 370(2), 1034-1045
    Publisher
    Royal Astronomical Society
    Enlace a la publicación
    http://dx.doi.org/10.1111/j.1365-2966.2006.10543.x
    Palabras clave
    Surveys
    Galaxies: high-redshift
    Quasars: general
    Early Universe
    Radio continuum: galaxies
    Abstract:
    We selected from the VLA FIRST survey a sample of 94 objects with star-like counterparts in the Sloan Digital Sky Survey (SDSS), and with APM POSS-I colour O−E≥ 2, i.e. consistent with their being high-redshift quasars. 78 of the 94 candidates can be classified spectroscopically on the basis of either published data (mainly SDSS) or the observations presented here. The fractions of QSOs (51 out of 78) and redshift z > 3 QSOs (23 out of 78, 29 per cent) are comparable to those found in other photometric searches for high-redshift QSOs. We confirm that selecting colour O−E≥ 2 ensures inclusion of all QSOs with 3.7 ≤z≤ 4.4. The fraction of 2 ≤z≤ 4.4 QSOs with broad absorption lines (BALs) is 27 ± 10 per cent (7/26) and the estimated BAL fraction for radio-loud QSOs is at least as high as for optically selected QSOs (∼13 per cent). Both the high BAL fraction and the high fraction of low-ionization BALs among BALs (four to five out of seven) in our sample, compared to previous work, are likely due to the red colour selection O−E≥ 2. The space density of radio-loud QSOs in the range with MAB(1450) ≤−26.6 and P≥ 1025.7 W Hz−1 is 1.7 ± 0.6 Gpc−3. Adopting a radio-loud fraction of 13.4 ± 3 per cent, this corresponds to ρ= 12.5 ± 5.6 Gpc−3, in substantial agreement with the cumulative luminosity function of SDSS QSOs in Fan et al. We note the unusual flat-spectrum radio-luminous QSO FIRST 1413+4505 (z= 3.11), which shows strong associated Lyα absorption (rest-frame equivalent width ∼40 Å) and an extreme observed luminosity, L∼ 2 × 1015 L⊙.
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    • D20 Artículos [328]
    • D52 Artículos [627]

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    UNIVERSIDAD DE CANTABRIA

    Repositorio realizado por la Biblioteca Universitaria utilizando DSpace software
    Contact Us | Send Feedback
    Metadatos sujetos a:licencia de Creative Commons Reconocimiento 3.0 España