The <i>Fermi</i> ‐LAT view of young radio sources

D’Ammando, F.; Orienti, M.; Giroletti, M.

doi:10.1002/asna.201512265

Cited by 17 publications

(19 citation statements)

References 47 publications

(45 reference statements)

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“…Grandi.) 10 44 erg s −1 or larger (see also Orienti et al 2011;D'Ammando et al 2016). The CSO PKS 1718−649 represents an ideal candidate to test this model, due to its linear size of only ∼2 pc and proximity (luminosity distance of 60.4 Mpc).…”

Section: Discussionmentioning

confidence: 99%

“…So far, γ-ray searches of young radio sources have not provided other significant detections (Migliori et al 2014;D'Ammando et al 2016). The 3FGL contains three γ-ray sources tentatively identified as compact steep-spectrum (CSS) radio sources (i.e., sources that likely are more evolved than CSOs): 3C 84 (Kataoka et al 2010;Dutson et al 2014), 3C 286, and 4C +39.23B (whose γ-ray association is however doubtful).…”

Section: Discussionmentioning

confidence: 99%

“…The radio lobes are expanding at sub-relativistic velocities; therefore, the γ-ray emission is expected to be isotropic and steady on short timescales (up to months/years). However, detections of the γ-ray emission from young radio sources have been so far elusive even with Fermi (Migliori et al 2014;D'Ammando et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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First Detection in Gamma-Rays of a Young Radio Galaxy: Fermi-Lat Observations of the Compact Symmetric Object PKS 1718−649

Migliori

Siemiginowska

Sobolewska

et al. 2016

ApJL

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We report the γ-ray detection of a young radio galaxy, PKS 1718−649, belonging to the class of compact symmetric objects (CSOs), with the Large Area Telescope (LAT) on board the Fermi satellite. The third Fermi Gamma-ray LAT catalog (3FGL) includes an unassociated γ-ray source, 3FGL J1728.0−6446, located close to PKS 1718−649. Using the latest Pass 8 calibration, we confirm that the best-fit 1σ position of the γ-ray source is compatible with the radio location of PKS 1718−649. Cross-matching of the γ-ray source position with the positions of blazar sources from several catalogs yields negative results. Thus, we conclude that PKS 1718−649 is the most likely counterpart to the unassociated LAT source. We obtain a detection test statistics TS ∼ 36 (>5σ) with a best-fit photon spectral index Γ = 2.9 ± 0.3 and a 0.1-100 GeV photon flux density F 0.1−100 GeV = (11.5 ± 0.3) × 10 −9 ph cm −2 s −1 . We argue that the linear size (∼2 pc), the kinematic age (∼100 years), and the source distance (z = 0.014) make PKS 1718−649 an ideal candidate for γ-ray detection in the framework of the model proposing that the most compact and the youngest CSOs can efficiently produce GeV radiation via inverseCompton scattering of the ambient photon fields by the radio lobe non-thermal electrons. Thus, our detection of the source in γ-rays establishes young radio galaxies as a distinct class of extragalactic high-energy emitters and yields a unique insight on the physical conditions in compact radio lobes interacting with the interstellar medium of the host galaxy.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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First Detection in Gamma-Rays of a Young Radio Galaxy: Fermi-Lat Observations of the Compact Symmetric Object PKS 1718−649

Migliori

Siemiginowska

Sobolewska

et al. 2016

ApJL

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“…The launch of the Fermi telescope in 2008 has opened the quest for YRSs in the γ-ray window. However, so far searches performed on selected samples have mainly reported upper limits (Migliori et al 2014;D'Ammando et al 2016;Migliori 2016a). A handful of γ-ray sources with uncertain classification show CSO-like features and are currently under investigation (see for example PMN J1603−4904, Müller et al 2015).…”

Section: Gamma-raysmentioning

confidence: 99%

Young radio sources at high-energies and the γ-ray CSO PKS 1718–649

Migliori¹

2018

Proc. IAU

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Observations at high-energies are important to define the first stages of the evolution of extragalactic radio sources and to characterize the interstellar medium of their host galaxies. In some of the X-ray-observed Compact Symmetric Objects (CSOs, among the youngest and most compact radio galaxies), we measured values of the total hydrogen column densities large enough to slow or prevent the radio source growth. The γ-ray window has the potential to constrain the non-thermal contribution of jets and lobes to the total high-energy emission. However, so far, young radio sources remain elusive in γ-rays, with only a handful of detections (or candidates) reported by Fermi. I present our γ-ray study of the CSO PKS 1718–649, and draw comparison with the restarted, γ-ray detected, radio galaxy 3C 84.

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“…The search for high-energy emission from young radio galaxies and quasars is crucial for investigating the energetic processes in the central region of the host galaxy, as well as the origin and the structure of the newly born radio jets. However, systematic searches of -rays from young radio sources have so far been unsuccessful [7]. Dedicated studies reported a handful of detections: three young radio galaxies (NGC 6328 [8], NGC 3894 [9] and TXS 0128+554 [10]), and five compact steep spectrum (CSS) sources (3C 138, 3C 216, 3C 286, 3C 380, and 3C 309.1) all associated with quasars [4FGL,11].…”

Section: Introductionmentioning

confidence: 99%