Extragalactic Peaked-spectrum Radio Sources at Low Frequencies

Callingham, JR; Ekers, RD; Gaensler, BM; Line, JLB; Hurley-Walker, N; Sadler, EM; Tingay, SJ; Hancock, PJ; Bell, ME; Dwarakanath, KS; For, BQ; Franzen, TMO; Hindson, L; Johnston-Hollitt, M; Kapińska, AD; Lenc, E; McKinley, B; Morgan, J; Offringa, AR; Procopio, P; Staveley-Smith, L; Wayth, RB; Wu, C; Zheng, Q

Extragalactic Peaked-spectrum Radio Sources at Low Frequencies

Callingham, JR Ekers, RD Gaensler, BM Line, JLB Hurley-Walker, N Sadler, EM Tingay, SJ Hancock, PJ Bell, ME

Dwarakanath, KS For, BQ Franzen, TMO Hindson, L Johnston-Hollitt, M Kapińska, AD Lenc, E McKinley, B Morgan, J Offringa, AR Procopio, P Staveley-Smith, L Wayth, RB Wu, C Zheng, Q

Permalink

Publication Type:: Journal Article
Citation:: Astrophysical Journal, 2017, 836 (2)
Issue Date:: 2017-02-20

Closed Access

	Filename	Description	Size
	Callingham_2017_ApJ_836_174.pdf	Published Version	3.16 MB	Adobe PDF	View/Open

Copyright Clearance Process

Recently Added
In Progress
Closed Access

This item is closed access and not available.

Full metadata record

Field	Value	Language
dc.contributor.author	Callingham, JR	en_US
dc.contributor.author	Ekers, RD	en_US
dc.contributor.author	Gaensler, BM	en_US
dc.contributor.author	Line, JLB	en_US
dc.contributor.author	Hurley-Walker, N	en_US
dc.contributor.author	Sadler, EM	en_US
dc.contributor.author	Tingay, SJ	en_US
dc.contributor.author	Hancock, PJ	en_US
dc.contributor.author	Bell, ME https://orcid.org/0000-0003-1767-5277	en_US
dc.contributor.author	Dwarakanath, KS	en_US
dc.contributor.author	For, BQ	en_US
dc.contributor.author	Franzen, TMO	en_US
dc.contributor.author	Hindson, L	en_US
dc.contributor.author	Johnston-Hollitt, M	en_US
dc.contributor.author	Kapińska, AD	en_US
dc.contributor.author	Lenc, E	en_US
dc.contributor.author	McKinley, B	en_US
dc.contributor.author	Morgan, J	en_US
dc.contributor.author	Offringa, AR	en_US
dc.contributor.author	Procopio, P	en_US
dc.contributor.author	Staveley-Smith, L	en_US
dc.contributor.author	Wayth, RB	en_US
dc.contributor.author	Wu, C	en_US
dc.contributor.author	Zheng, Q	en_US
dc.date.issued	2017-02-20	en_US
dc.identifier.citation	Astrophysical Journal, 2017, 836 (2)	en_US
dc.identifier.issn	0004-637X	en_US
dc.identifier.uri	http://hdl.handle.net/10453/124774
dc.description.abstract	© 2017. The American Astronomical Society. All rights reserved. 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.	en_US
dc.relation.ispartof	Astrophysical Journal	en_US
dc.relation.isbasedon	10.3847/1538-4357/836/2/174	en_US
dc.subject.classification	Astronomy & Astrophysics	en_US
dc.title	Extragalactic Peaked-spectrum Radio Sources at Low Frequencies	en_US
dc.type	Journal Article
utslib.citation.volume	2	en_US
utslib.citation.volume	836	en_US
utslib.for	0201 Astronomical and Space Sciences	en_US
utslib.for	0305 Organic Chemistry	en_US
utslib.for	0306 Physical Chemistry (incl. Structural)	en_US
utslib.for	0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
utslib.copyright.status	closed_access
pubs.issue	2	en_US
pubs.publication-status	Published	en_US
pubs.volume	836	en_US

Abstract:

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

Please use this identifier to cite or link to this item:

http://hdl.handle.net/10453/124774