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    Extragalactic Peaked-spectrum Radio Sources at Low Frequencies

    250654.pdf (3.090Mb)
    Access Status
    Open access
    Authors
    Callingham, J.
    Ekers, Ronald
    Gaensler, B.
    Line, J.
    Hurley-Walker, Natasha
    Sadler, E.
    Tingay, Steven
    Hancock, Paul
    Bell, M.
    Dwarakanath, K.
    For, B.
    Franzen, Thomas
    Hindson, L.
    Johnston-Hollitt, M.
    Kapinska, A.
    Lenc, E.
    McKinley, B.
    Morgan, J.
    Offringa, A.
    Procopio, P.
    Staveley-Smith, L.
    Wayth, Randall
    Wu, C.
    Zheng, Q.
    Date
    2017
    Type
    Journal Article
    
    Metadata
    Show full item record
    Citation
    Callingham, J. and Ekers, R. and Gaensler, B. and Line, J. and Hurley-Walker, N. and Sadler, E. and Tingay, S. et al. 2017. Extragalactic Peaked-spectrum Radio Sources at Low Frequencies. Astrophysical Journal. 836: 174.
    Source Title
    Astrophysical Journal
    DOI
    10.3847/1538-4357/836/2/174
    ISSN
    0004-637X
    School
    Curtin Institute of Radio Astronomy (Engineering)
    Remarks

    Copyright © 2017 The American Astronomical Society. All rights reserved.

    URI
    http://hdl.handle.net/20.500.11937/51477
    Collection
    • Curtin Research Publications
    Abstract

    We present a sample of 1483 sources that display spectral peaks between 72 MHz and 1.4 GHz, selected from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. The GLEAM survey is the widest fractional bandwidth all-sky survey to date, ideal for identifying peaked-spectrum sources at low radio frequencies. Our peaked-spectrum sources are the low-frequency analogs of gigahertz-peaked spectrum (GPS) and compact-steep spectrum (CSS) sources, which have been hypothesized to be the precursors to massive radio galaxies. Our sample more than doubles the number of known peaked-spectrum candidates, and 95% of our sample have a newly characterized spectral peak. We highlight that some GPS sources peaking above 5 GHz have had multiple epochs of nuclear activity, and we demonstrate the possibility of identifying high-redshift (z > 2) galaxies via steep optically thin spectral indices and low observed peak frequencies. The distribution of the optically thick spectral indices of our sample is consistent with past GPS/CSS samples but with a large dispersion, suggesting that the spectral peak is a product of an inhomogeneous environment that is individualistic. We find no dependence of observed peak frequency with redshift, consistent with the peaked-spectrum sample comprising both local CSS sources and high-redshift GPS sources. The 5 GHz luminosity distribution lacks the brightest GPS and CSS sources of previous samples, implying that a convolution of source evolution and redshift influences the type of peaked-spectrum sources identified below 1 GHz. Finally, we discuss sources with optically thick spectral indices that exceed the synchrotron self-absorption limit. © 2017. The American Astronomical Society. All rights reserved.

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