The ATLAS 9.0 GHz survey of the extended Chandra Deep Field South: the faint 9.0 GHz radio population

Huynh, Minh; Seymour, N.; Norris, R. P.; Galvin, T. J.

doi:10.1093/mnras/stz3187

Cited by 12 publications

(7 citation statements)

References 87 publications

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“…For the canonical synchrotron radiation spectral index of −0.7, our peak S-band completeness limit is equal to 50 μJy beam −1 at 1.4 GHz. Our median value is consistent with previous dual-band studies at comparable depths (e.g., Huynh et al 2015;Gim et al 2019;Huynh et al 2020), as well as inband measurements made using the 1-2 GHz L-band receivers of the VLA (Heywood et al 2016(Heywood et al , 2020. We note also that the dual-band studies involving measurements at ∼5 GHz and above also revealed a significant fraction of flat and inverted spectrum sources in addition to those with typical synchrotron spectra, something that is also evident in Figure 4.…”

Section: Spectral Indices Of Compact Radio Sourcessupporting

confidence: 91%

The VLA Frontier Fields Survey: Deep, High-resolution Radio Imaging of the MACS Lensing Clusters at 3 and 6 GHz

Heywood

Murphy

Jiménez-Andrade

et al. 2021

ApJ

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The Frontier Fields project is an observational campaign targeting six galaxy clusters, with the intention of using the magnification provided by gravitational lensing to study galaxies that are extremely faint or distant. We used the Karl G. Jansky Very Large Array (VLA) at 3 and 6 GHz to observe three Frontier Fields: MACS J0416.1 −2403 (z = 0.396), MACS J0717.5+3745 (z = 0.545), and MACS J1149.5+2223 (z = 0.543). The images reach noise levels of ∼1 μJy beam −1 with subarcsecond resolution (∼2.5 kpc at z = 3), providing a high-resolution view of high-z star-forming galaxies that is unbiased by dust obscuration. We generate dual-frequency continuum images at two different resolutions per band, per cluster, and derive catalogs totaling 1966 compact radio sources. Components within the areas of Hubble Space Telescope and Subaru observations are cross-matched, providing host galaxy identifications for 1296 of them. We detect 13 moderately lensed (2.1 < μ < 6.5) sources, one of which has a demagnified peak brightness of 0.9 μJy beam −1 , making it a candidate for the faintest radio source ever detected. There are 66 radio sources exhibiting complex morphologies, and 58 of these have host galaxy identifications. We reveal that MACS J1149.5+2223 is not a cluster with a double relic, as the western candidate relic is resolved as a double-lobed radio galaxy associated with a foreground elliptical at z = 0.24. The VLA Frontier Fields project is a public legacy survey. The image and catalog products from this work are freely available.

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Section: Spectral Indices Of Compact Radio Sourcessupporting

confidence: 91%

The VLA Frontier Fields Survey: Deep, High-resolution Radio Imaging of the MACS Lensing Clusters at 3 and 6 GHz

Heywood

Murphy

Jiménez-Andrade

et al. 2021

ApJ

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“…Processing and data reduction were conducted using the Multichannel Image Reconstruction, Image Analysis and Display (MIRIAD) software package (Sault, Teuben, & Wright 1995), similar to the method outlined by Huynh et al (2015; 2020). The 1435 region D pointings are restored with the Gaussian fit of the dirty beam and convolved to a common beam of 4 arcsec 2 arcsec (BPA = ) at 5.5 GHz and achieves an RMS of Jy beam –1 .…”

Section: Datamentioning

confidence: 99%

Remnant radio galaxies discovered in a multi-frequency survey

Quici

Hurley‐Walker

Seymour

et al. 2021

Publ. Astron. Soc. Aust.

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The remnant phase of a radio galaxy begins when the jets launched from an active galactic nucleus are switched off. To study the fraction of radio galaxies in a remnant phase, we take advantage of a $8.31$ deg $^2$ subregion of the GAMA 23 field which comprises of surveys covering the frequency range 0.1–9 GHz. We present a sample of 104 radio galaxies compiled from observations conducted by the Murchison Widefield Array (216 MHz), the Australia Square Kilometer Array Pathfinder (887 MHz), and the Australia Telescope Compact Array (5.5 GHz). We adopt an ‘absent radio core’ criterion to identify 10 radio galaxies showing no evidence for an active nucleus. We classify these as new candidate remnant radio galaxies. Seven of these objects still display compact emitting regions within the lobes at 5.5 GHz; at this frequency the emission is short-lived, implying a recent jet switch off. On the other hand, only three show evidence of aged lobe plasma by the presence of an ultra-steep-spectrum ( $\alpha<-1.2$ ) and a diffuse, low surface brightness radio morphology. The predominant fraction of young remnants is consistent with a rapid fading during the remnant phase. Within our sample of radio galaxies, our observations constrain the remnant fraction to $4\%\lesssim f_{\mathrm{rem}} \lesssim 10\%$ ; the lower limit comes from the limiting case in which all remnant candidates with hotspots are simply active radio galaxies with faint, undetected radio cores. Finally, we model the synchrotron spectrum arising from a hotspot to show they can persist for 5–10 Myr at 5.5 GHz after the jets switch of—radio emission arising from such hotspots can therefore be expected in an appreciable fraction of genuine remnants.

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“…Number counts of extragalactic radio sources are well determined at radio frequencies ν 10 GHz down to flux densities of S 1 mJy (and even S 0.03 mJy at 1.4 GHz) based on data from deep and large area surveys (e.g. Bondi et al 2008;De Zotti et al 2010;Bonavera et al 2011;Massardi et al 2011;Miller et al 2013;Smolčić et al 2017;Puglisi et al 2018;Huynh et al 2020). At higher frequencies, that is, from tens of GHz to millimetre (mm) wavelengths, observational data on radio sources are mainly provided by CMB experiments (e.g.…”

Section: Number Counts At CM To Mm Wavelengthsmentioning

confidence: 99%

Impact of polarised extragalactic sources on the measurement of CMBB-mode anisotropies

Lagache

Béthermin

Montier

et al. 2020

A&A

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One of the main goals of cosmology is to search for the imprint of primordial gravitational waves in the polarisation filed of the cosmic microwave background to probe inflation theories. One of the obstacles in detecting the primordial signal is that the cosmic microwave background B-mode polarisation must be extracted from among astrophysical contaminations. Most efforts have focus on limiting Galactic foreground residuals, but extragalactic foregrounds cannot be ignored at the large scale (ℓ ≲ 150), where the primordial B-modes are the brightest. We present a complete analysis of extragalactic foreground contamination that is due to polarised emission of radio and dusty star-forming galaxies. We update or use current models that are validated using the most recent measurements of source number counts, shot noise, and cosmic infrared background power spectra. We predict the flux limit (confusion noise) for future cosmic microwave background (CMB) space-based or balloon-borne experiments (IDS, PIPER, SPIDER, LiteBIRD, and PICO), as well as ground-based experiments (C-BASS, NEXT-BASS, QUIJOTE, AdvACTPOL, BICEP3+Keck, BICEPArray, CLASS, Simons Observatory, SPT3G, and S4). The telescope aperture size (and frequency) is the main characteristic that affects the level of confusion noise. Using the flux limits and assuming mean polarisation fractions independent of flux and frequency for radio and dusty galaxies, we computed the B-mode power spectra of the three extragalactic foregrounds (radio source shot noise, dusty galaxy shot noise, and clustering). We discuss their relative levels and compare their amplitudes to that of the primordial tensor modes parametrised by the tensor-to-scalar ratio r. At the reionisation bump (ℓ = 5), contamination by extragalactic foregrounds is negligible. While the contamination is much lower than the targeted sensitivity on r for large-aperture telescopes at the recombination peak (ℓ = 80), it is at a comparable level for some of the medium- (∼1.5 m) and small-aperture telescope (≤0.6 m) experiments. For example, the contamination is at the level of the 68% confidence level uncertainty on the primordial r for the LiteBIRD and PICO space-based experiments. These results were obtained in the absence of multi-frequency component separation (i.e. considering each frequency independently). We stress that extragalactic foreground contaminations have to be included in the input sky models of component separation methods dedicated to the recovery of the CMB primordial B-mode power spectrum. Finally, we also provide some useful unit conversion factors and give some predictions for the SPICA B-BOP experiment, which is dedicated to Galactic and extragalactic polarisation studies. We show that SPICA B-BOP will be limited at 200 and 350 μm by confusion from extragalactic sources for long integrations in polarisation, but very short integrations in intensity.

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The ATLAS 9.0 GHz survey of the extended Chandra Deep Field South: the faint 9.0 GHz radio population

Cited by 12 publications

References 87 publications

The VLA Frontier Fields Survey: Deep, High-resolution Radio Imaging of the MACS Lensing Clusters at 3 and 6 GHz

The VLA Frontier Fields Survey: Deep, High-resolution Radio Imaging of the MACS Lensing Clusters at 3 and 6 GHz

Remnant radio galaxies discovered in a multi-frequency survey

Impact of polarised extragalactic sources on the measurement of CMBB-mode anisotropies

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