M87 having distinguished structure, originates atthe core and

M87 is one of the most studied and the nearest radiogalaxy located in the Virgo cluster.Having short distance to the observer (16.4 Mpc, z=0.00436)(Blakeslee et al. 2009; Jordán etal. 2005) and being enriched with peculiar structures, such us bright core as well as powerfulone-sided jet (Shklovsky 1964), M87 gives us opportunity to explore the nature of the AGNs.The large SMBH mass equal to (3-6.6)x109 Mo (Macchetto et al.1997; Gebhardt & Thomas2009;3 Sargent et al. 1978, Young et al. 1978) endows numerous astrophysical phenomena.Although the accurate value of the BH mass is still questionable. The first known jet of theM87 discovered optically by Curtis (1918) and having distinguished structure, originates atthe core and extends outward more than (Marshall et al. 2002; Harris et al. 2003). Theinner structures of the jet are resolved in the X-ray, optical and radio wavebands A.S.Wilson, & Y. Yang.The jet formation and collimation processes have been essential targets of study for manyyears (Begelman, M. C., Blandford) and M87 is a unique laboratory where it is possible toexplore the collimation region of the jet occurring at ~30–100 Schwarzschild radii (rS) fromthe black hole (W. Junor, J.A. Biretta), using high-frequency radio very long baselineinterferometry (VLBI) observations with sub-milliarcsecond (mas) resolution. Near the core,at the collimation region the opening angel of the jet is widening (~60o). Also it isnoteworthy to mention that the Hubble Space Telescope (HST) observations have exposedeight features in the inner of the core, with optical superluminal velocity in the range 4c6c.Lorentz factor and 19 degree jet viewing angle were required for describing theobserved fastest motions, which confirm that the bulk flow of the jet is relativistic (Biretta etal. 1999).The structure of the M87 jet has been minutely discussed due to Very Large Array(VLA)/Very Long Baseline Interferometry (VLBI) observations during the past three decades.From (Asada & Nakamura 2012), at small distances (< 105 Schwarzschild radii) the jetretained parabolic and subsequently the jet is manifested as a conical shape and the origin ofthe HST-1 is the result of the overcollimation of the jet. Another interesting result by (Hada2017) approves the existence of a triple-ridge structure across the jet based on the radioobservations of M87 jet with the VLBA at 15 GHz.

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