From the ‘blazar sequence' to unification of blazars and radio galaxies

Xiong, Dingrong; Zhang, Xiong; Bai, J. M.; Zhang, Haojing

doi:10.1093/mnras/stv1038

Cited by 17 publications

(7 citation statements)

References 45 publications

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“…The distribution of the synchrotron peak luminosity as a function of the synchrotron peak energy for the EHBLs is presented in Figure 4. The synchrotron peak luminosity for the known EHBLs is obtained between 10 44 -10 45 erg sec −1 which is consistent with the values estimated for blazars in the range 10 43 -10 47 erg sec −1 [58,59]. The values of the synchrotron peak luminosity (∼ 10 45 erg sec −1 ) for Mrk 501 reported in the literature are in agreement with the values estimated for the EHBLs in the present study [52,57].…”

Section: Synchrotron Peak Luminositysupporting

confidence: 92%

Extremely High energy peaked BL Lac nature of the TeV blazar Mrk 501

et al. 2019

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Extremely High energy peaked BL Lac (EHBL) objects are a special class of blazars with peculiar observational properties at X-ray and γ-ray energies. The observations of these sources indicate hard X-ray and γ-ray spectra and absence of rapid flux variations in the multi-wavelength light curves. These observational features challenge the leptonic models for blazars due to unusually hard particle spectrum in the emission region of the blazar jet and provide a strong motivation for exploring alternative scenarios to interpret the broad-band emission from blazars. At present, only few TeV blazars have been observed as EHBL objects in the extragalactic Universe. Due to their hard γ-ray spectra and long term variability, the observations of EHBL type of blazars at different redshifts help in probing the cosmic magnetic field and extragalactic background light in the Universe. Such objects also provide astrophysical sites to explore the particle acceleration mechanisms like magnetic reconnection and second order Fermi acceleration. Therefore, it has become important to identify more objects as EHBL using the observations available in the literature. Recent studies on the blazar Mrk 501 indicate that this source may exhibit an EHBL behaviour. In this paper, we use long term observations of Mrk 501 to explore its nature. Two sets of data, related to low and high/flaring activity states of Mrk 501, have been presented and compared with the observed features of a few well known EHBL type of blazars.We find that the spectral features of the blazar Mrk 501 indicate an EHBL nature of the source. Whereas, the temporal characteristics with fast variability during the high activity state of the source in X-ray and γ-ray energy bands are not compatible with the behaviour of EHBL type of blazars. However, Mrk 501 can be considered as an EHBL candidate in its low emission state. We also discuss the implications of identifying more EHBL objects using present and future groundbased γ-ray observatories.

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Section: Synchrotron Peak Luminositysupporting

confidence: 92%

Extremely High energy peaked BL Lac nature of the TeV blazar Mrk 501

et al. 2019

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“…The observational differences are due to the anisotropic radiation caused by Doppler beaming effect (Urry & Padovani 1995). This unification scenario between blazars and radio galaxies has been verified in the literatures by many authors (Bai & Lee 2001;Xu et al 2009;Xiong et al 2015). In this paper, we compare the jet powers (extended jet emission) for BZCAT blazars and 3CR radio galaxies.…”

Section: The Unification Between Blazars and Radio Galaxiessupporting

confidence: 73%

Jet Power of Jetted Active Galactic Nuclei: Implications for Evolution and Unification

Fan

Wu²

2019

ApJ

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We construct samples of jetted active galactic nuclei (AGNs) with low-frequency radio data from the recent released TGSS AD1 catalog at 150 MHz. With these samples, we compare the properties of jet power for blazars, radio-loud narrow-line Seyfert 1 galaxies (RL-NLS1s), young radio sources (YRSs) and radio galaxies. The jet-disk connection, and the unification of jetted AGNs are explored. On the Eddington ratio -Eddington-scaled jet power plane, jetted AGNs can be generally divided into two populations. Low power radio galaxies, low excitation FR IIs (LEG/FR IIs), and most YRSs show larger jet power than accretion power, while FSRQs, RL-NLS1s, and high excitation FR IIs (HEG/FR IIs) are on the contrary. LEG/FR IIs share similar jet power properties with HEG/FR IIs, while their accretion properties are different with the latter. These facts suggest an evolutional sequence from HEG/FR IIs, LEG/FR IIs to FR Is, where the accretion and jet activities get dimmed gradually. LEG/FR IIs are the transitional objects that accretion processes have switched off, while jets are still active. After correcting the contribution from radio core of blazars, the unification between blazars and radio galaxies is confirmed with the jet power distributions. The unification involved RL-NLS1s is more complicated than the simple scenarios of black hole growth or orientation effect. In addition, our results manifest that low synchrotron peaked BL Lacs (LBLs) contain two distinct groups on the distribution of jet power, with one group similar with FSRQs and the other similar with intermediate synchrotron peaked BL Lacs. The LBLs with higher jet powers might be the aligned counterparts of LEG/FR IIs.

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“…Giommi et al (2012) concluded from their Monte-Carlo simulations that there are only two intrinsic blazar types, low-ionization sources consisting mostly of beamed Fanaroff-Riley type I (FR I) galaxies and high-ionization sources of mostly beamed FR II ones. Xiong et al (2015) also found an anti-correlation between jet power and beamcorrected synchrotron peak frequency of blazars and radio galaxies. Hervet et al (2016) approached the blazar classification using very-long-baseline-interferometry (VLBI) maps, resulting in three classes with different radio knot kinematics.…”

Section: Introductionmentioning

confidence: 69%