Non-thermal emission in radio galaxy lobes – II. Centaurus A, Centaurus B, and NGC 6251

Peršić, M.; Rephaeli, Yoel

doi:10.1093/mnras/stz2527

Cited by 9 publications

(6 citation statements)

References 57 publications

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“…the SED modeling (Persic & Rephaeli 2019), and is also in agreement with the values in the radio lobes of some RGs, which are obtained by the X-ray measurements (e.g., Croston et al 2005;Kataoka & Stawarz 2005;Isobe et al 2011).…”

Section: Broadband Sed Modeling and γ-Ray Originsupporting

confidence: 88%

Lobe-dominated γ-Ray Emission of Compact Symmetric Objects

Gan,

Zhang,

Yang

et al. 2024

Res. Astron. Astrophys.

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The $\gamma$-ray emitting compact symmetric objects (CSOs) PKS 1718--649, NGC 3894, and TXS 0128+554 are lobe-dominated in the radio emission. In order to investigate their $\gamma$-ray radiation properties, we analyze the $\sim$14-yr Fermi/LAT observation data of the three CSOs. They all show the low luminosity ($10^{41}-10^{43}$ erg s$^{-1}$) and no significant variability in the $\gamma$-ray band. Their $\gamma$-ray average spectra can be well fitted by a power-law function. These properties of $\gamma$-rays are clearly different from the $\gamma$-ray emitting CSOs CTD 135 and PKS 1413+135, for which the $\gamma$-rays are produced by a restarted aligned jet. In the $L_{\gamma}-\Gamma_{\gamma}$ plane, the three CSOs are also located at the region occupied by radio galaxies (RGs) while CTD 135 and PKS 1413+135 display the similar feature to blazars. Together with the similar radio emission property to $\gamma$-ray emitting RGs Cen A and Fornax A, we speculate that the $\gamma$-rays of the three CSOs stem from their extended mini-lobes. The broadband spectral energy distributions of the three CSOs can be well explained by the two-zone leptonic model, where their $\gamma$-rays are produced by the inverse Compton process of the relativistic electrons in extended region. By extrapolating the observed Fermi/LAT spectra to the very high energy band, we find that TXS 0128+554 among the three CSOs may be detected by the Cherenkov Telescope Array in future.

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Section: Broadband Sed Modeling and γ-Ray Originsupporting

confidence: 88%

Lobe-dominated γ-Ray Emission of Compact Symmetric Objects

Gan,

Zhang,

Yang

et al. 2024

Res. Astron. Astrophys.

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“…For the core region, the radio and optical-UV data are collected from Migliori et al (2011), X-rays are the combined spectrum using the latest 11 X-ray Telescope (XRT) observations (see Appendix B), and γ-rays are obtained by the analysis in this work. For the NW lobe, the radio and X-ray data are collected from Takeuchi et al (2012) and Persic & Rephaeli (2019), while the γ-ray data are obtained by the analysis in this work.…”

Section: Constructing and Modeling The Sedmentioning

confidence: 99%

Fermi Large Area Telescope Detection of Gamma Rays from the NGC 6251 Radio Lobe

Yu,

Zhang,

Gan

et al. 2024

ApJ

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We report the detection of extended γ-ray emission from lobes in the radio galaxy NGC 6251 using observation data from the Fermi Large Area Telescope. The maximum likelihood analysis results show that a radio morphology template provides a better fit than a pointlike source description for the observational data at a confidence level of 8.1σ, and the contribution of lobes constitutes more than 50% of the total γ-ray flux. Furthermore, the γ-ray energy spectra show a significant disparity in shape between the core and lobe regions, with a curved log-parabola shape observed in the core region and a power-law form observed in the lobes. Neither the core region nor the northwest (NW) lobe displays significant flux variations in the long-term γ-ray light curves. The broadband spectral energy distributions of the core region and the NW lobe can be explained with a single-zone leptonic model. The γ-rays of the core region are due to the synchrotron-self-Compton process, while the γ-rays from the NW lobe are interpreted as inverse Compton emission of the cosmic microwave background.

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“…The IR and optical parameters allow us to model the GFL; in our calculations we take 𝑇 gal, OPT = 2900 K and 𝑇 gal, IR = 29 K (Persic & Rephaeli 2019a). The lobe X-ray data are spatial averages, so we correspondingly compute volume-averaged Compton/GFL yields based on the fact that lobe sizes and projected distances (from the central galaxy) are much larger than the size of the galaxy, which we treat as a point source (Persic & Rephaeli 2019b).…”

Section: Lobe 𝛾-Ray Emissionmentioning

confidence: 99%

IGR J18249-3243: a new GeV-emitting FR II and the emerging population of high energy radio galaxies

Bruni,

Bassani,

Persic

et al. 2022

Preprint

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The advent of new all-sky radio surveys such as the VLA Sky Survey (VLASS) and the Rapid ASKAP Continuum Survey (RACS), performed with the latest generation radio telescopes, is opening new possibilities on the classification and study of extragalactic 𝛾-ray sources, specially the underrepresented ones like radio galaxies. In particular, the enhanced sensitivity (sub-mJy level) and resolution (a few arcsec) provides a better morphological and spectral classification. In this work, we present the reclassification of a Fermi-LAT source as a new FRII radio galaxy from the INTEGRAL sample found to emit at GeV energies. Through a broad-band spectral fitting from radio to 𝛾-ray, we find that the commonly invoked jet contribution is not sufficient to account for the observed 𝛾-ray flux. Our modeling suggests that the observed emission could mainly originate in the lobes (rather than in the radio core) by inverse Compton scattering of radio-emitting electrons off the ambient photon fields. In addition, we cross-correlated the latest generation radio surveys with a list of Fermi-LAT objects from the literature considered to be candidate misaligned AGN, finding four new radio galaxies with a double-lobed morphology. Additional four objects could be classified as such thanks to previous studies in the literature, for a total of nine new radio galaxies with GeV emission presented in this work. We foresee that further objects of this class might be found in the near future with the advent of the Square Kilometer Array (SKA), populating the GeV sky.

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Non-thermal emission in radio galaxy lobes – II. Centaurus A, Centaurus B, and NGC 6251

Cited by 9 publications

References 57 publications

Lobe-dominated γ-Ray Emission of Compact Symmetric Objects

Lobe-dominated γ-Ray Emission of Compact Symmetric Objects

Fermi Large Area Telescope Detection of Gamma Rays from the NGC 6251 Radio Lobe

IGR J18249-3243: a new GeV-emitting FR II and the emerging population of high energy radio galaxies

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