Anatomy of a blazar in the (sub-)millimeter: ALMA observations of PKS 0521-365

Léon, S.; Cortés, Paulo C.; Guerard, M.; Villard, Eric; Hidayat, Taufiq; Flaquer, B. Ocaña; Vila-Vilaro, Baltasar

doi:10.1051/0004-6361/201527146

Cited by 11 publications

(15 citation statements)

References 45 publications

(63 reference statements)

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“…0521-365. Our VLBI results complete the multiwavelength picture provided by Tingay & Edwards (2002), D'Ammando et al (2015, and Leon et al (2016), confirming that the jet of PKS 0521−36 is not highly beamed, with viewing angles larger than 10 • still compatible with our observations. Pian et al (1996) used multi-wavelength data to model the broadband SED of PKS 0521−36, and found that the source is likely not Doppler-boosting dominated, with an estimated viewing angle of θ = 30 • ±6 • and a Doppler factor δ ∼ 1.5.…”

Section: Individual Sourcessupporting

confidence: 88%

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Gamma-ray emission in radio galaxies under the VLBI scope

Angioni

Ros

Kadler

et al. 2019

A&A

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Aims. In the framework of the multi-wavelength and very long baseline interferometry (VLBI) monitoring program TANAMI (Tracking Active Nuclei with Austral Milliarcsecond Interferometry), we study the evolution of the parsec-scale radio emission in radio galaxies in the southern hemisphere and their relationship to the γ-ray properties of the sources. Our study investigates systematically, for the first time, the relationship between the two energy regimes in radio galaxies. In this first paper, we focus on Fermi-LAT-detected sources. Methods. The TANAMI program monitors a large sample of radio-loud AGN at 8.4 GHz and 22.3 GHz with the Australian long baseline array (LBA) and associated telescopes in Antarctica, Chile, New Zealand and South Africa. We performed a kinematic analysis for five γ-ray detected radio galaxies using multi-epoch 8.4 GHz VLBI images, deriving limits on intrinsic jet parameters such as speed and viewing angle. We analyzed 103 months of Fermi-LAT data in order to study possible connections between the γ-ray properties and the pc-scale jets of Fermi-LAT-detected radio galaxies, both in terms of variability and average properties. We discuss the individual source results and draw preliminary conclusions on sample properties including published VLBI results from the MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) survey, with a total of fifteen sources. Results. We find that the first γ-ray detection of Pictor A might be associated with the passage of a new VLBI component through the radio core, which appears to be a defining feature of high-energy emitting Fanaroff-Riley type II radio galaxies. We detect subluminal parsec-scale jet motions in the peculiar AGN PKS 0521−36, and we confirm the presence of fast γ-ray variability in the source down to timescales of six hours, which is not accompanied by variations in the VLBI jet. We robustly confirm the presence of significant superluminal motion, up to βapp ∼ 3, in the jet of the TeV radio galaxy PKS 0625−35. Our VLBI results constrain the jet viewing angle to be θ < 53°, allowing for the possibility of a closely aligned jet. Finally, by analyzing the first pc-scale multi-epoch images of the prototypical compact symmetric object (CSO) PKS 1718−649, we place an upper limit on the separation speed between the two mini-lobes. This in turn allows us to derive a lower limit on the age of the source. Conclusions. We can draw some preliminary conclusions on the relationship between pc-scale jets and γ-ray emission in radio galaxies, based on Fermi-LAT-detected sources with available multi-epoch VLBI measurements. We find that the VLBI core flux density correlates with the γ-ray flux, as seen in blazars. On the other hand, the γ-ray luminosity does not show any dependence on the core brightness temperature and core dominance, which are two common indicators of jet Doppler boosting. This seems to indicate that γ-ray emission in radio galaxies is not driven by orientation-dependent effects, as in blazars, in accordance with the unified model of jetted AGN.

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Section: Individual Sourcessupporting

confidence: 88%

“…This is a nearby AGN with an uncertain classification. Leon et al (2016) derive limits on the jet viewing angle, speed, and Doppler factor using the Atacama Large Millimeter Array (ALMA). Their results suggest a jet viewing angle in the range 16 • ≤ θ ≤ 38 • , from the jet-to-counterjet ratio.…”

Section: -458 (Pictor A)mentioning

confidence: 99%

Gamma-ray emission in radio galaxies under the VLBI scope

Angioni

Ros

Kadler

et al. 2019

A&A

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“…We do not detect extended emission in the direction of the counter-jet in our long-slit spectroscopic nor optical imaging data (see Fig. 1, 3); which might be due to the fact that relativistic beaming enhance the approaching jet flux and dim the receding one (Leon et al 2016). The optical 1D spectra from the optical jet emission and the central engine were obtained by co-adding emission along the spatial axis in the 2D spectrum (see Fig.…”

Section: Resultsmentioning

confidence: 65%

Detection of helicoidal motion in the optical jet of PKS 0521−365

Jiménez-Andrade

Chavushyan

Patiño-Álvarez

et al. 2017

Monthly Notices of the Royal Astronomical Society: Letters

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The jet activity of Active Galactic Nuclei (AGN), and its interaction with the interstellar medium (ISM), may play a pivotal role in the processes which regulate the growth and star formation of its host galaxy. Observational evidence which pinpoints the conditions of such interaction is paramount to unveil the physical processes involved. We report on the discovery of extended emission line regions exhibiting an S-shaped morphology along the optical jet of the radio-loud AGN PKS 0521−365 (z = 0.055), by using long-slit spectroscopic observations obtained with FORS2 on VLT. The velocity pattern derived from the [O II] λ3727Å, Hβ λ4861Å and [O III] λλ4959, 5007Å emission lines is well-fitted by a sinusoidal function of the form: v(r) = αr 1/2 sin(βr 1/2 + γ), suggesting helicoidal motions along the jet up to distances of 20 kpc. We estimate a lower limit for the mass of the outflowing ionized gas along the jet of ∼10 4 M . Helical magnetic fields and jet precession have been proposed to explain helicoidal paths along the jet at pc scales; nevertheless, it is not clear yet whether these hypotheses may hold at kpc scales.

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“…0521−365 This is a nearby AGN with an uncertain classification. Leon et al (2016) (2015) constrain the same parameters using SED modeling including γ-ray data, obtaining a more aligned jet viewing angle of 6 • ≤ θ ≤ 15 • . These results point to an intermediate jet viewing angle between a blazar and a steep spectrum radio quasar (SSRQ) or Broad Line Radio Galaxy (BLRG).…”

Section: −458 (Pictor A)mentioning

confidence: 99%

Gamma-ray emission in radio galaxies under the VLBI scope -- I. Parsec-scale kinematics and high-energy properties of $γ$-ray detected TANAMI radio galaxies

Angioni,

Ros,

Kadler

et al. 2019

Preprint

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Aims. In the framework of the TANAMI multi-wavelength and VLBI monitoring, we study the evolution of the parsec-scale radio emission in radio galaxies in the southern hemisphere and their relationship to the γ-ray properties of the sources. Our study investigates systematically, for the first time, the relationship between the two energy regimes in radio galaxies. In this first paper, we focus on Fermi-LAT-detected sources. Methods. The TANAMI program monitors a large sample of radio-loud AGN at 8.4 GHz and 22.3 GHz with the Australian Long Baseline Array (LBA) and associated telescopes in Antarctica, Chile, New Zealand and South Africa. We perform a kinematic analysis for five γ-ray detected radio galaxies using multi-epoch 8.4 GHz VLBI images, deriving limits on intrinsic jet parameters such as speed and viewing angle. We analyzed 103 months of Fermi-LAT data in order to study possible connections between the γ-ray properties and the pc-scale jets of Fermi-LAT-detected radio galaxies, both in terms of variability and average properties. We discuss the individual source results and draw preliminary conclusions on sample properties including published VLBI results from the MOJAVE survey, with a total of fifteen sources. Results. We find that the first γ-ray detection of Pictor A might be associated with the passage of a new VLBI component through the radio core, which appears to be a defining feature of high-energy emitting Fanaroff-Riley type II radio galaxies. For the peculiar AGN PKS 0521−36, we detect subluminal parsec-scale jet motions, and we confirm the presence of fast γ-ray variability in the source down to timescales of 6 hours, which is not accompanied by variations in the VLBI jet. We robustly confirm the presence of significant superluminal motion, up to β app ∼ 3, in the jet of the TeV radio galaxy PKS 0625−35. Our VLBI results constrain the jet viewing angle to be θ < 53 • , allowing for the possibility of a closely aligned jet. Finally, by analyzing the first pc-scale multi-epoch images of the prototypical Compact Symmetric Object (CSO) PKS 1718−649, we place an upper limit on the separation speed between the two mini-lobes, which in turn allows us to derive a lower limit on the age of the source. Conclusions. We can draw some preliminary conclusions on the relationship between pc-scale jets and γ-ray emission in radio galaxies, based on Fermi-LAT-detected sources with available multi-epoch VLBI measurements. We find that the VLBI core flux density correlates with the γ-ray flux, as seen in blazars. On the other hand, the γ-ray luminosity does not show any dependence on the core brightness temperature and core dominance, two common indicators of jet Doppler boosting. This seems to indicate that γ-ray emission in radio galaxies is not driven by orientation-dependent effects, as in blazars, which is consistent with the unified model of jetted AGN.

show abstract

Anatomy of a blazar in the (sub-)millimeter: ALMA observations of PKS 0521-365

Cited by 11 publications

References 45 publications

Gamma-ray emission in radio galaxies under the VLBI scope

Gamma-ray emission in radio galaxies under the VLBI scope

Detection of helicoidal motion in the optical jet of PKS 0521−365

Gamma-ray emission in radio galaxies under the VLBI scope -- I. Parsec-scale kinematics and high-energy properties of $γ$-ray detected TANAMI radio galaxies

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