Compact Steep-Spectrum Radio Sources and Ambient Medium Density
International Journal of Astrophysics and Space Science
Volume 3, Issue 1, February 2015, Pages: 1-6
Received: Jan. 13, 2015; Accepted: Feb. 6, 2015; Published: Feb. 16, 2015
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Ezeugo Jeremiah Chukwuemerie, Department of Physics and Industrial physics, NnamdiAzikiwe University, Awka, Anambra State, Nigeria
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Analytical and statistical methods,with some plausible assumptions, have been used in this work to show presence of dense medium around compact steep-spectrum sources in our sample. This is done by carrying out regression analyses using our estimated jet’s internal densities (n_j ) and some other source parameters for possible deductions. Results indicate that n_j-D and n_j-n_e data (where D and n_e are respectively, observed source linear size and ambient medium density) show strong correlations and yield power-law relations of the forms, n_j~D^(-3.54±0.02) and n_j~n_e^(1.68±0.08). A comparison with obtained theoretical relations suggestively indicates presence of dense gases around these sources. In addition, a simple linear regression analysis of ν_p-n_j data shows that jet’s particles may be responsible (in addition to the ambient gases) for the observed spectral turnover characteristic of compact steep spectrum sources.
Spectral Turnover, Steep-Spectrum, Astrophysical Jet, Ambient Density, Active Galaxies
To cite this article
Ezeugo Jeremiah Chukwuemerie, Compact Steep-Spectrum Radio Sources and Ambient Medium Density, International Journal of Astrophysics and Space Science. Vol. 3, No. 1, 2015, pp. 1-6. doi: 10.11648/j.ijass.20150301.11
C. E. Akujor, andS. T.Garrington,“Compactsteep-spectrum sources – polarization observations at1.6, 8.4 and 15GHz,”Astron and Astrophy. Suppl. Ser.,vol. 122, pp. 235-255, 1995
C. Fanti, R.Fanti, D. C.Dallacasa,R. T.Schilizzi,R. E.Spencer,and C.Stanghellini,“Are compactsteep-spectrum sources young?”Astron. and Astrophy., vol. 302, pp. 317-326, 1995
C. P. O’Dea, “The compact steep-spectrum sources andGigahertz peaked-spectrum radio sources”, Pub. Astron.Soc. Ppacific,vol. 110, pp. 493-532, 1998
C. A. Jackson,“Radio source evolution and unifiedschemes,” Publ. Astron. Soc. Aust., vol. 16, pp.124-129, 1999
J. Machalski,M.Jamrozy,and D. J.Saikia,“A multifrequency study of giant radio sources III. Dynamicalage vs. spectral age of the lobes of selected sources”,Mont. Not. Roy. Ast. Soc., vol. 395, pp. 812-824, 2009
D. J. Saikia,S.Jeyakumar,P. J.Wiita,H. S.Sanghera,andR. E.Spencer, “Compact steep-spectrum radiosources and unification schemes,” Mon. Not. Roy. Ast.Soc., vol. 276, pp. 1215-1223, 1995
C. J. Stanghellini,D.Dallacasa,C. P. O'Dea,S. A.Baum,R. Fanti,C. Fanti,“VLBA observations ofGHz-peaked-spectrum radio sources at 15GHz,”Astron. and Astrophy., vol. 377, pp. 377-388, 2001
J. A. Peacock, andJ. V. Wall, “Bright extragalacticradio sources at 2.7GHz-II,” Mont. Not. Roy. Ast. Soc.,vol. 198, pp. 843-860, 1982
M. Murgia,R.Fanti, L.Gregorini, U. Klein,K. H.Mark,andM. Vigotti, “Synchrotron spectra and ages ofcompact steep spectrum radio sources,”Astron. andAstrophy., vol. 345, pp. 769-777, 1999
S. Koide,K. Shibata,and T.Kudoh,“Relativistic jetformation from black hole magnetized accretion disks,”,The Astrophy. Journ., vol. 522, pp.727-752, 1999
A. Bongiorno, A. Merloni, M. Brusa, B. Magnelli, M. Salvato, M. Mignoli, G. Zamorani, F. Fiore, D. Rosario, V. Mainieri, H. Hao, A. Comastri, C. Vignali, I. Balestra, S. Bardelli, S. Berta, F. Civano, P. Kampczyk, E. Le Floc'h, E. Lusso, D. Lutz, L. Pozzetti, F. Pozzi, L. Riguccini, F. Shankar, andJ. Silverman, “Accreting supermassive black holes in the COSMOS field and the connection to their host galaxies,”Mon. Not. Roy Ast. Soc., vol. 427, pp. 3103-3133, 2012
I. Robson, Active Galactic Nuclei, England: John Wileyand Sons, 1996, pp. 269-307
R. D. Blandford,and D. G. Payne,“Hydromagneticflows from accretion discs and the production of radiojets,”Mont. Not. Roy. Ast. Soc., vol. 199, pp. 883-903,1982
G. V. Ustyugova,A. V.Koldoba,M. M.Romanova,V.M.Chechetkin,and R. V. E Lovelace,“Magnetohydrodynamic simulations of outflows from accretiondisks,”Astrophys. Journal, vol. 439, pp. L39-L42, 1995
A. C. S. Readhead,G. B. Taylor,W. Xu, T. J. Pearson,P. N. Wilkinson, A. G. Polatidis,“The statistics andages of compact symmetric objects,”The Astrophy.Journ., vol. 460, pp. 612-633, 1996
J. C. Cavalho, “The evolution of GHz-peaked-spectrumradio sources,” Astronomy and Astrophysics, vol. 329,pp. 845-852, 1998
F. Santoro, J. B. R. Oonk, R. Morganti, and T. Oosterloo, “The jet-ISM interaction in the outer filament of Centaurus A,”Astron. and Astrophy., vol. 574, A89, 2015
J. C. Ezeugo,andA. A. Ubachukwu, “The spectralturnover-linear size relation and the dynamical evolution of compact steep spectrum sources”, Mon. Not.Roy Ast. Soc, vol. 408, pp.2256-2260,2010
I. A. G. Snellen,R. T.Schilizzi,G. K. Miley,M. N.Bremer,H. J. A. Rottgering, andH. J. van Langevelde,“Faint gigahertz peaked spectrum sources and the evolution of young radio sources,” New Ast. Rev., vol. 43,pp. 675-679, 1999
I. Owsianik, andJ. E. Conway,“First detection ofhotspot advance in a compact symmetric object” Astron. and Astrophy., vol. 337, pp. 69-79, 1998
W. Tschager,R. T.Schilizzi,I. A. G.Snellen,A. G. deBruyn, G. K. Miley, H. J. A. Rottgering, H. J. van Langevelde,C. Fanti,and R.Fanti, “VSOP/global VLBIobservations of 2021+614: detection of hotspot advance,” New Ast. Rev., vol. 43, pp. 681-684, 1999
C. P. O'Dea, R. A. Dally, P. Kharb, andK. A. Freeman,“Physical properties of very powerful FRII radio galaxies”, Astro. and Astrophys., vol. 494, pp. 471, 2009
F. Mantovani,W. Junior,M.Bondi,W. Cotton,R. Fanti,L.Padrielli,G. D. Nicolson,and E. Salerno,“Largebent jets in the inner region of CSSs,” Astron. andAstrophy., vol. 332, pp. 10-18, 1998
S. Jeyakumar,P. J.Wiita, D. J.Saikia, andJ. S.Hooda,“Jet propagation and the asymmetries of CSS radiosources,” Astron. and Astrophy., vol. 432, pp. 823-833,2005
A. Labiano,“Tracing jet-ISM interaction in youngAGN: correlations between [O III] λ 500 A ̇ and 5GHzemission”, Astron. and Astrophy., 488, vol. L59-L62,2008
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