Linear radio size evolution of <i>μ</i>Jy populations

Bondì, M.; Zamorani, G.; Ciliegi, P.; Smolčić, Vernesa; Schinnerer, E.; Delvecchio, I.; Jiménez-Andrade, E. F.; Liu, Daizhong; Lang, P.; Magnelli, B.; Murphy, E. J.; Vardoulaki, E.

doi:10.1051/0004-6361/201834243

Cited by 33 publications

(49 citation statements)

References 52 publications

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“…Error bars denote the uncertainties on the derived SF rates. with SFR radio ≈ SFR optical−FIR are typically a factor of 2 larger than those for which SFR radio exceeds by more than 3σ SFR optical−FIR (Bondi et al 2018). This is fully consistent with SF-related radio emission in the former sources.…”

Section: Star Formationsupporting

confidence: 80%

The origin of radio emission from radio-quiet active galactic nuclei

et al. 2019

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The central nuclei of galaxies, where super-massive black holes (SMBHs) are thought to reside, can experience phases of activity when they become Active Galactic Nuclei (AGN). An AGN can eject winds, jets, and produce radiation across the entire electromagnetic spectrum. The fraction of the bolometric emission in the radio spans a factor of ∼10 5 across the different AGN classes. The weakest radio sources, radio-quiet (RQ) AGN, are typically 1,000 times fainter than the radio-loud (RL) AGN, and represent the majority of the AGN population. In RL AGN, radio emission is essentially all produced by synchrotron emission from a relativistic jet. In contrast, in RQ AGN the absence of luminous jets allows us to probe radio emission from a wide range of possible mechanisms, from the host galaxy kpc scale down to the innermost region near the SMBHs: star formation, AGN driven wind, free-free emission from photo-ionized gas, low power jet, and the innermost accretion disc coronal activity. All these mechanisms can now be probed with unprecedented precision and spatial resolution, thanks to the current and forthcoming generation of highly sensitive radio arrays.

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Section: Star Formationsupporting

confidence: 80%

The origin of radio emission from radio-quiet active galactic nuclei

et al. 2019

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“…The median radio sizes are 7.7 ± 0.2 and 6.7 ± 0.1 kpc above and below the median luminosity, respectively. This increase in radio size with radio luminosity is consistent with the findings of Bondi et al (2018), whose study on the size evolution of the 3-GHz-selected VLA-COSMOS sample (Smolčić et al 2017) uncovered similar behaviour for both the radio-loud AGN and radioquiet AGN in their sample. Our near-unity radio-to-optical size ratio is in tension with a results from the VLA COSMOS 3 GHz study (Jiménez-Andrade et al 2019), whose median radio size is ∼1.3-2 times smaller than the optical/UV continuum emission which traces the stellar component.…”

Section: The Radio Sizes Of Sfgs and Agn From Z = 1-3supporting

confidence: 89%

The e-MERGE Survey (e-MERLIN Galaxy Evolution Survey): overview and survey description

Muxlow

Thomson

Radcliffe

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present an overview and description of the e-MERGE Survey (e-MERLIN Galaxy Evolution Survey) Data Release 1 (DR1), a large program of high-resolution 1.5-GHz radio observations of the GOODS-N field comprising ∼140 h of observations with enhanced-Multi-Element Remotely Linked Interferometer Network (e-MERLIN) and ∼40 h with the Very Large Array (VLA). We combine the long baselines of e-MERLIN (providing high angular resolution) with the relatively closely packed antennas of the VLA (providing excellent surface brightness sensitivity) to produce a deep 1.5-GHz radio survey with the sensitivity (${\sim}1.5\, \mu$ Jy beam−1), angular resolution (0.2–0.7 arcsec) and field-of-view (∼15 × 15 arcmin2) to detect and spatially resolve star-forming galaxies and active galactic nucleus (AGN) at $z$ ≳ 1. The goal of e-MERGE is to provide new constraints on the deep, sub-arcsecond radio sky which will be surveyed by SKA1-mid. In this initial publication, we discuss our data analysis techniques, including steps taken to model in-beam source variability over an ∼20-yr baseline and the development of new point spread function/primary beam models to seamlessly merge e-MERLIN and VLA data in the uv plane. We present early science results, including measurements of the luminosities and/or linear sizes of ∼500 galaxies selected at 1.5 GHz. In combination with deep Hubble Space Telescope observations, we measure a mean radio-to-optical size ratio of re-MERGE/rHST ∼ 1.02 ± 0.03, suggesting that in most high-redshift galaxies, the ∼GHz continuum emission traces the stellar light seen in optical imaging. This is the first in a series of papers that will explore the ∼kpc-scale radio properties of star-forming galaxies and AGN in the GOODS-N field observed by e-MERGE DR1.

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“…This resulted in a synthesized beam of 2 14×1 81 at 3 GHz and 2 33×2 01 at 10 GHz. The near-equal resolution of ∼2 0 was chosen to be large enough to avoid resolving typical faint radio sources, which are generally subarcsecond in size at the μJy level (Bondi et al 2018;Cotton et al 2018). In turn, this resolution allows for the cleanest measurement of their radio flux densities, while ensuring that confusion noise remains negligible (Paper I).…”

Section: Radio Datamentioning

confidence: 99%

A Multiwavelength Analysis of the Faint Radio Sky (COSMOS-XS): the Nature of the Ultra-faint Radio Population

Algera

Vlugt

Hodge

et al. 2020

ApJ

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Ultra-deep radio surveys are an invaluable probe of dust-obscured star formation, but require a clear understanding of the relative contribution from radio active galactic nuclei (AGNs) to be used to their fullest potential. We study the composition of the μJy radio population detected in the Karl G. Jansky Very Large Array COSMOS-XS survey based on a sample of 1540 sources detected at 3 GHz over an area of ∼350 arcmin 2 . This ultra-deep survey consists of a single pointing in the well-studied COSMOS field at both 3 and 10 GHz and reaches rms sensitivities of 0.53 and 0.41 μJy beam −1 , respectively. We find multiwavelength counterparts for 97% of radio sources, based on a combination of near-UV/optical to sub-millimeter data, and through a stacking analysis at optical/near-IR wavelengths we further show that the sources lacking such counterparts are likely to be high-redshift in nature (typical z∼4−5). Utilizing the multiwavelength data over COSMOS, we identify AGNs through a variety of diagnostics and find these to make up 23.2±1.3% of our sample, with the remainder constituting uncontaminated star-forming galaxies. However, more than half of the AGNs exhibit radio emission consistent with originating from star formation, with only 8.8±0.8% of radio sources showing a clear excess in radio luminosity. At flux densities of ∼30 μJy at 3 GHz, the fraction of star formation-powered sources reaches ∼90%, and this fraction is consistent with unity at even lower flux densities. Overall, our findings imply that ultra-deep radio surveys such as COSMOS-XS constitute a highly effective means of obtaining clean samples of star formation-powered radio sources.

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Linear radio size evolution of μJy populations

Cited by 33 publications

References 52 publications

The origin of radio emission from radio-quiet active galactic nuclei

The origin of radio emission from radio-quiet active galactic nuclei

The e-MERGE Survey (e-MERLIN Galaxy Evolution Survey): overview and survey description

A Multiwavelength Analysis of the Faint Radio Sky (COSMOS-XS): the Nature of the Ultra-faint Radio Population

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