The GLEAM 200-MHz local radio luminosity function for AGN and star-forming galaxies
| Autor: | T. Mauch, Bryan Gaensler, Bi-Qing For, John Morgan, A. R. Offringa, Anna D. Kapińska, K. S. Dwarakanath, C. A. Jackson, Pietro Procopio, B. Quici, Luke Hindson, Chen Wu, Sarah V. White, Rajan Chhetri, Elaine M. Sadler, Thomas M. O. Franzen, Lister Staveley-Smith, Nick Seymour, Melanie Johnston-Hollitt, Martin Bell, Benjamin McKinley, Q. Zheng, Randall B. Wayth, Joseph R. Callingham, Natasha Hurley-Walker, Emil Lenc, Paul Hancock |
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| Rok vydání: | 2021 |
| Předmět: |
Data Analysis
Active galactic nucleus Radio Continuum Active Astrophysics::High Energy Astrophysical Phenomena Population FOS: Physical sciences Starburst Murchison Widefield Array Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Astronomy & Astrophysics Surveys Luminosity Methods 0201 Astronomical and Space Sciences 0299 Other Physical Sciences education Astrophysics::Galaxy Astrophysics Luminosity function (astronomy) Physics Spectral index education.field_of_study Star formation Astronomy and Astrophysics Galaxies Catalogues Astrophysics - Astrophysics of Galaxies Galaxy Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) |
| Zdroj: | Publications of the Astronomical Society of Australia, 38 |
| ISSN: | 1448-6083 1323-3580 |
| Popis: | The GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) is a radio continuum survey at 76-227 MHz of the entire southern sky (Declination $ 55$ mJy across an area of $\approx 16,700~\mathrm{deg}^{2}$. From the optical spectra, we identify the dominant physical process responsible for the radio emission from each galaxy: 73 per cent are fuelled by an active galactic nucleus (AGN) and 27 per cent by star formation. We present the local radio luminosity function for AGN and star-forming galaxies at 200 MHz and characterise the typical radio spectra of these two populations between 76 MHz and $\sim 1$ GHz. For the AGN, the median spectral index between 200 MHz and $\sim 1$ GHz, $\alpha_{\mathrm{high}}$, is $-0.600 \pm 0.010$ (where $S \propto \nu^{\alpha}$) and the median spectral index within the GLEAM band, $\alpha_{\mathrm{low}}$, is $-0.704 \pm 0.011$. For the star-forming galaxies, the median value of $\alpha_{\mathrm{high}}$ is $-0.650 \pm 0.010$ and the median value of $\alpha_{\mathrm{low}}$ is $-0.596 \pm 0.015$. Among the AGN population, flat-spectrum sources are more common at lower radio luminosity, suggesting the existence of a significant population of weak radio AGN that remain core-dominated even at low frequencies. However, around 4 per cent of local radio AGN have ultra-steep radio spectra at low frequencies ($\alpha_{\mathrm{low}} < -1.2$). These ultra-steep-spectrum sources span a wide range in radio luminosity, and further work is needed to clarify their nature. Comment: 28 pages, 18 figures, accepted for publication in PASA |
| Databáze: | OpenAIRE |
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