Oral Presentation

Jet Formation, Particle Acceleration, and High Energy Emission: Hints from 3C 84

Author(s): Hiroshi Nagai (NAOJ)

Presenter: Hiroshi Nagai (NAOJ)

The radio source 3C 84 is associated with the giant elliptical/radio galaxy NGC 1275 (z = 0.0176). Due to its brightness and proximity, this source is one of the best-studied radio sources in history. The very long baseline interferometry (VLBI) observations revealed that a recent increased activity in radio bands originated in the restarted jet activity starting in about 2005 (Nagai et al. 2010). The restarted jet is resolved in the transverse direction and found to be limb brightened (Nagai et al. 2014; Giovannini et al. in preparation) as also seen in M87 and other nearby radio galaxies. In 1990s, the jet limb-brightening was not observed even with the observations with a similar spatial resolution and sensitivity (Dhawan et al. 1997). The jet morphology was rather ridge brightening. Such a change has not been observed in any other radio sources, and thus 3C 84 provides a unique opportunity to understand the origin of ridge/limb brightening. This change in the jet morphology also shows an interesting agreement with the gamma-ray flux increase, i.e., the gamma-ray flux in the 1990s was at least 10 times lower than the current one. In Nagai et al. (2014), we proposed that the change from ridge brightening to limb brightening may be attributed to a change in the transverse velocity structure on the basis of a “spine-sheath” scenario. In this presentation, we will present additional VLBI observation data and argue the origin of limb brightening and gamma-ray emission using a few different models, which might be applicable to M87. We will also argue the similarities and differences between 3C 84 and M87 in terms of multi wavelength properties, and also comment on the unification of radio-loud AGNs.