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    The Micro-Arcsecond Scintillation-Induced Variability (Masiv) Survey. III. Optical Identifications and New Redshifts

    193850_98700_Macquart-Micro-Arcsecond.pdf (1011.Kb)
    Access Status
    Open access
    Authors
    Pursimo, T
    Ojha, R
    Jauncey, David
    Rickett, B
    Dutka, M
    Koay, J
    Lovell, J
    Bignall, Hayley
    Kedziora-Chudczer, L
    Macquart, Jean-Pierre
    Date
    2013
    Type
    Journal Article
    
    Metadata
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    Citation
    Pursimo, T and Ojha, R and Jauncey, David and Rickett, B and Dutka, M and Koay, J and Lovell, J and Bignall, Hayley and Kedziora-Chudczer, L and Macquart, Jean-Pierre. 2013. The Micro-Arcsecond Scintillation-Induced Variability (Masiv) Survey. III. Optical Identifications and New Redshifts. The Astrophysical Journal. 767: 14.
    Source Title
    The Astrophysical Journal
    DOI
    10.1088/0004-637X/767/1/14
    ISSN
    0004637X
    Remarks

    Reproduced by permission of The American Astronomical Society (AAS)

    URI
    http://hdl.handle.net/20.500.11937/42993
    Collection
    • Curtin Research Publications
    Abstract

    Intraday variability (IDV) of the radio emission from active galactic nuclei is now known to be predominantly due to interstellar scintillation (ISS). The MASIV (The Micro-Arcsecond Scintillation-Induced Variability) survey of 443 flat spectrum sources revealed that the IDV is related to the radio flux density and redshift. A study of the physical properties of these sources has been severely handicapped by the absence of reliable redshift measurements for many of these objects. This paper presents 79 new redshifts and a critical evaluation of 233 redshifts obtained from the literature. We classify spectroscopic identifications based on emission line properties, finding that 78% of the sources have broad emission lines and are mainly FSRQs. About 16% are weak lined objects, chiefly BL Lacs, and the remaining 6% are narrow line objects. The gross properties (redshift, spectroscopic class) of the MASIV sample are similar to those of other blazar surveys. However, the extreme compactness implied by ISS favors FSRQs and BL Lacs in the MASIV sample as these are the most compact object classes. We confirm that the level of IDV depends on the 5 GHz flux density for all optical spectral types. We find that BL Lac objects tend to be more variable than broad line quasars. The level of ISS decreases substantially above a redshift of about two. The decrease is found to be generally consistent with ISS expected for beamed emission from a jet that is limited to a fixed maximum brightness temperature in the source rest frame.

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