| The GPS (Gigahertz Peaked-Spectrum) and CSS (compact steep-spectrum) radio sources makes up significant fractions of the bright (centimeter-wavelength-selected) radio source population (~10%and ~30%, respectively). In this thesis, I reviewed, explicatively, the radio to X-ray properties of GPS/CSS sources, the current hypotheses for their origin, and their use to constrain the evolution of powerful radio galaxies. CSS radio sources often show disturbed kinematics of the interstellar gas coupled with associated radio components, providing evidence for gas outflow. The interaction between radio jets and the host galaxy ISM may be responsible for the jet confinement to small scales and can contribute to the ionization of the medium and lead to star formation. Detailed study of the circumnuclear region is essential in understanding the processes that drive the kinematics, physical conditions and morphology of the line emitting gas. GPS/CSS radio sources, which are very similar to the large scale classic double sources. However, great differences are obvious. The quasar, (z=0.368)3C 48 is an unusual CSS radio sources, with a very weak central core. The structure is very complex, whose one-sided radio jet is aligned with the extended ionized emission. The radio morphology suggested that the jet is interacting with its immediate environment. It has excess far-IR emission. Surely, lots of gas and large of young stars were found in the host galaxy by optical and infrared observations. 3C 48, because of its high AGN luminosity and low redshift, is a good candidate to search for kinematic signatures of the radio jet-gas coupling and/or of a recent interaction. The study on 3C 48 is based on the data sets coming from the high sensitive instruments of VLA and MERLIN. The observations were carried out at multi-frequency on multi-epoch, including 10 datasets at P, C, L, X, K wavelengths with 4 epochs. The radio radiation of 3C 48 are come from within 0.6arcsecond (H 0 =65km s ?1 Mpc ?1 , q 0 =0.5). The source is an unresovled compact structure with the resolution lower than 0.5arcsecond, and is resolved with the resolution higher than 0.5arcsecond. The whole radio structure is dominated by a jet directing to north. We fitted Gaussian models to the self-calibrated (u,v) data sets, 3C 48 is composed of four (N1, N2, N3, and S) components. The main jet NE to the core is dominated by 3 components (N1, N2, N3), at south, a significantly extended component, S, ( > 20σ) emission has been detected. Multi-frequencies observations allowed us to analysis the spectral index distribution 3C 48. The spectral index experiences a flip of "steep-flat-steep"along the radio axes, and the flat spectral was happened at RA ~ 01h34m49.820s±0.02s, DEC ~ 320 54'19.740''±0.013'' nearly. We thought it as the core of the source. Most importantly, an extended steep spectral component S ( > 20σ) is surely detected, about 0.25arcsecond tothe flat-spectrum core, αs~ ?0.7±0.14 between 1.6 and 8.4GHz. Both the Location and the steep spectral nature suggest that the feature is most likely to be the counter-jet,which identified that 3C 48 is not intrinsically one-sided jet radio source, it is two-sided jets. The high sensitive observations tell us that the jet of 3C 48 directed to north was dispersed in east-west direction, which is indeed due to the strong interaction between the jet and ISM. The jet merged into ISM, producing shocks, the interactions converted the kinetic energy carried by the jet to internal energy or turbulence which could enhance the acceleration of the particles and then produce the radiation-field, causing the jet brightened, so that observed north jet brightened (hot spot) after losing collimation, and dispersed in the direction of east-west. |
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