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

Panessa, F.; Baldi, Ranieri D.; Laor, Ari; Padovani, P.; Behar, E.; McHardy, I. M.

doi:10.1038/s41550-019-0765-4

Cited by 227 publications

(234 citation statements)

References 173 publications

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“…The latter is a combination of free-free emission, which has an almost flat radio spectrum, and steep synchrotron emission from supernova remnants. When combined, these lead to an observed spectral index of ∼0.7, which is characteristic of star-forming galaxies, and roughly in agreement with the spectral indexes of our sources (e.g., Condon 1992;Panessa et al 2019).…”

Section: Star Formation At Low Frequenciessupporting

confidence: 87%

Absorbed relativistic jets in radio-quiet narrow-line Seyfert 1 galaxies

Berton

Järvelä

Crepaldi

et al. 2020

A&A

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Narrow-line Seyfert 1 (NLS1) galaxies are peculiar active galactic nuclei (AGN). Most of them do not show strong radio emission, but recently seven radio-quiet (or -silent) NLS1s have been detected flaring multiple times at 37 GHz by the Metsähovi Radio Telescope, indicating the presence of relativistic jets in these peculiar sources. We observed them with the Karl G. Jansky Very Large Array (JVLA) in A configuration at 1.6, 5.2, and 9.0 GHz. Our results show that these sources are either extremely faint or not detected in the JVLA bands. At those frequencies, the radio emission from their relativistic jet must be absorbed, either via synchrotron selfabsorption as it occurs in gigahertz-peaked sources or, more likely, via free-free absorption by a screen of ionized gas associated with starburst activity or shocks. Our findings cast new shadows on the radio-loudness criterion, which seems to be more and more frequently a misleading parameter. New high-frequency and high-resolution radio observations are essential to test our hypotheses.

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Section: Star Formation At Low Frequenciessupporting

confidence: 87%

Absorbed relativistic jets in radio-quiet narrow-line Seyfert 1 galaxies

Berton

Järvelä

Crepaldi

et al. 2020

A&A

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“…This suggests that the fundamental differences between rQSOs and cQSOs become apparent at R < −3.4, possibly due to a different process starting to dominate the radio emission. However, whether this process is due to AGN-driven winds, frustrated jets, star-formation or a coronal component (to name a few) is unclear (Zakamska & Greene 2014;Kellermann et al 2016;Laor et al 2019;Panessa et al 2019;Jarvis et al 2019). An enhanced fraction of broad absorption line QSOs (BALQ-SOs; known to host powerful winds) have been found in red QSOs (Urrutia et al 2009), which could be evidence that red QSOs are more wind dominated than typical QSOs.…”

Section: S82 14 Ghzmentioning

confidence: 99%

Fundamental differences in the radio properties of red and blue quasars: enhanced compact AGN emission in red quasars

Fawcett

Alexander

Rosario

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We have recently used the Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey to show that red quasars have fundamentally different radio properties to typical blue quasars: a significant (factor ≈ 3) enhancement in the radio-detection fraction, which arises from systems around the radio-quiet threshold with compact (< 5 ) radio morphologies. To gain greater insight into these physical differences, here we use the DR14 Sloan Digital Sky Survey (SDSS) and more sensitive, higher resolution radio data from the Very Large Array (VLA) Stripe 82 (S82) and VLA-COSMOS 3 GHz (C3GHz) surveys. With the S82 data, we perform morphological analyses at a resolution and depth three times that of the FIRST radio survey, and confirm an enhancement in radio-faint and compact red quasars over typical quasars; we now also find tentative evidence for an enhancement in red quasars with slightly extended radio structures (16-43 kpc at z = 1.5). These analyses are complemented by C3GHz, which is deep enough to detect radio emission from star-formation processes. From our data we find that the radio enhancement from red quasars is due to AGN activity on compact scales ( 43 kpc) for radio-intermediate-radio-quiet sources (−5 < R < −3.4, where R = L 1.4GHz /L 6µm ), which decreases at R < −5 as the radio emission from star-formation starts to dilute the AGN component. Overall our results argue against a simple orientation scenario and are consistent with red quasars representing a younger, earlier phase in the overall evolution of quasars.

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“…where νL ν is the radio power andf R is a dimensionless factor. In general, the radio emission of radio-quiet sources can have different origins (Panessa et al 2019, and references therein); in any case, assuming that the observed 1.4 GHz flux of HE 1143-1810 is due to a jet, and takingṁ = 0.8 and r J = 19 R G , we derivẽ f R = 1.3 × 10 −9 . Interestingly, this factor is not too far from that derived by Marcel et al (2019) for the X-ray binary GX 339-4 (f R = 4.5 × 10 −10 ).…”

Section: A Jet-emitting Disc?mentioning

confidence: 99%

NuSTAR/XMM–Newton monitoring of the Seyfert 1 galaxy HE 1143-1810

Ursini¹,

Petrucci

Bianchi

et al. 2020

A&A

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Aims. We test the two-corona accretion scenario for active galactic nuclei in the case of the 'bare' Seyfert 1 galaxy HE 1143-1810. Methods. We perform a detailed study of the broad-band UV-X-ray spectral properties and of the short-term variability of HE 1143-1810. We present results of a joint XMM-Newton and NuSTAR monitoring of the source, consisting of 5 × 20 ks observations, each separated by 2 days, performed in December 2017. Results. The source is variable in flux among the different observations, and a correlation is observed between the UV and X-ray emission. Moderate spectral variability is observed in the soft band. The time-averaged X-ray spectrum exhibits a cut-off at ∼ 100 keV consistent with thermal Comptonization. We detect an iron Kα line consistent with being constant during the campaign and originating from a mildly ionized medium. The line is accompanied by a moderate, ionized reflection component. A soft excess is clearly present below 2 keV and is well described by thermal Comptonization in a 'warm' corona with a temperature of ∼ 0.5 keV and a Thomson optical depth of ∼ 17 − 18. For the hot hard X-ray emitting corona, we obtain a temperature of ∼ 20 keV and an optical depth of ∼ 4 assuming a spherical geometry. A fit assuming a jet-emitting disc (JED) for the hot corona also provides a nice description of the broad-band spectrum. In this case, the data are consistent with an accretion rate varying between ∼ 0.7 and ∼ 0.9 in Eddington units and a transition between the outer standard disc and the inner JED at ∼ 20 gravitational radii. Conclusions. The broad-band high-energy data agree with an accretion flow model consisting of two phases: an outer standard accretion disc with a warm upper layer, responsible for the optical-UV emission and the soft X-ray excess, and an inner slim JED playing the role of a hard X-ray emitting hot corona.

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

Cited by 227 publications

References 173 publications

Absorbed relativistic jets in radio-quiet narrow-line Seyfert 1 galaxies

Absorbed relativistic jets in radio-quiet narrow-line Seyfert 1 galaxies

Fundamental differences in the radio properties of red and blue quasars: enhanced compact AGN emission in red quasars

NuSTAR/XMM–Newton monitoring of the Seyfert 1 galaxy HE 1143-1810

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