What are the megahertz peaked-spectrum sources?

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What are the megahertz peaked-spectrum sources?

Journal Article (2016)

Author(s)

Rocco Coppejans (Radboud Universiteit Nijmegen)

Dávid Cseh (Radboud Universiteit Nijmegen)

Sjoert van Velzen (Johns Hopkins University)

Heino Falcke (Netherlands Institute for Radio Astronomy (ASTRON))

Huib T. Intema (Universiteit Leiden)

Zsolt Paragi (Joint Institute for VLBI ERIC)

Cornelia Müller (Radboud Universiteit Nijmegen)

Wendy L. Williams (University of Hertfordshire)

Sándor Frey (FöMI Satellite Geodetic Observatory)

Leonid I. Gurvits (TU Delft - Astrodynamics & Space Missions, Joint Institute for VLBI ERIC)

Elmar G. Körding (Radboud Universiteit Nijmegen)

Techniques: interferometric Galaxies: high-redshift Galaxies: active Techniques: high angular resolution Radio continuum: galaxies

DOI related publication

https://doi.org/10.1093/mnras/stw799 Final published version

To reference this document use

https://resolver.tudelft.nl/uuid:47b3d134-9ec8-4ff0-9cb1-863a7856a88a

More Info

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Publication Year

2016

Language

English

Journal title

Royal Astronomical Society. Monthly Notices

Issue number

3

Volume number

459

Pages (from-to)

2455-2471

Downloads counter

231

Abstract

Megahertz peaked-spectrum (MPS) sources have spectra that peak at frequencies below 1 GHz in the observer's frame and are believed to be radio-loud active galactic nuclei (AGN). We recently presented a new method to search for high-redshift AGN by identifying unusually compact MPS sources. In this paper, we present European VLBI Network (EVN) observations of 11 MPS sources which we use to determine their sizes and investigate the nature of the sources with ~10 mas resolution. Of the 11 sources, we detect 9 with the EVN. Combining the EVN observations with spectral and redshift information, we show that the detected sources are all AGN with linear sizes smaller than 1.1 kpc and are likely young. This shows that low-frequency colour-colour diagrams are an easy and efficient way of selecting small AGN and explains our high detection fraction (82 per cent) in comparison to comparable surveys. Finally we argue that the detected sources are all likely compact symmetric objects and that none of the sources are blazars.