PKS 2215+020

PKS 2215+020 is an optically faint and radio-loud quasar (S_5 GHz = 0.50.6 Jy).^[3][4] Included as part of the Parkes Half-Jansky Flat Spectrum Sample,^[5] the quasar has a corresponding linear scale of 3.38 h⁻¹ pc mas⁻¹ and deceleration parameter of q₀ = 0.5, which its radio spectral index of 2215+020 is a 5 GHz divided by 2.7 GHz = -0.15 (Sv ∞ vx). From X-ray emission observation with ROSAT in 1998, a minimum evidence for possible elongation along the P.A. = 60°-70° is found.^[6]

PKS 2215+020 is a blazar,^[7] a type of active galaxy shooting out a jet towards the direction of Earth, according to researchers who studied its jet components. They found out that the quasar contains a nearly proper motion (0.02 mas/yr) superluminal jet about two times the speed of light. PKS 2215+020 has a delta of =11.5 for the Doppler-boosting factor, which they found that the inner relativistic jet inclined within 2 degrees to line of sight, with a Lorentz factor of Gamma=6 bulk.^[8]

Further observations from the VSOP observation, found out the jet in PKS 2215+020 has an interesting morphology. They observed that extent of the jet is remarkable showing >80 mas, 250 h⁻¹ pc. Moreover, the jet structures observed in 2215+020 are 10 time larger compared to quasars at z > 3 observed with VLBI, suggesting the jet has a working surface.^[9]

The supermassive black hole in the center of PKS 2215+020 has an estimated 4 billion solar masses (M_☉).^[10] According to resolution images of the quasar, researchers found there is rich core-jet structure, unusually large, based on the linear scales from 5 h⁻¹ to 300 h⁻¹ pc (H0 = 100 h km s-1 Mpc-1).^[10] This makes PKS 2215+020 to have the longest jet observed, so far at a redshift greater than 3. Through comparing similarities with the VLA and ROSAT observations, an extended radio/X-ray halo surrounding PKS 2215+020 is present.^[11]