Volume 3, Issue 1, February 2015, Page: 1-6
Compact Steep-Spectrum Radio Sources and Ambient Medium Density
Ezeugo Jeremiah Chukwuemerie, Department of Physics and Industrial physics, NnamdiAzikiwe University, Awka, Anambra State, Nigeria
Received: Jan. 13, 2015;       Accepted: Feb. 6, 2015;       Published: Feb. 16, 2015
DOI: 10.11648/j.ijass.20150301.11      View  2224      Downloads  97
Abstract
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.
Keywords
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
Reference
[1]
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
[2]
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
[3]
C. P. O’Dea, “The compact steep-spectrum sources andGigahertz peaked-spectrum radio sources”, Pub. Astron.Soc. Ppacific,vol. 110, pp. 493-532, 1998
[4]
C. A. Jackson,“Radio source evolution and unifiedschemes,” Publ. Astron. Soc. Aust., vol. 16, pp.124-129, 1999
[5]
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
[6]
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
[7]
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
[8]
J. A. Peacock, andJ. V. Wall, “Bright extragalacticradio sources at 2.7GHz-II,” Mont. Not. Roy. Ast. Soc.,vol. 198, pp. 843-860, 1982
[9]
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
[10]
S. Koide,K. Shibata,and T.Kudoh,“Relativistic jetformation from black hole magnetized accretion disks,”,The Astrophy. Journ., vol. 522, pp.727-752, 1999
[11]
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
[12]
I. Robson, Active Galactic Nuclei, England: John Wileyand Sons, 1996, pp. 269-307
[13]
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
[14]
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
[15]
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
[16]
J. C. Cavalho, “The evolution of GHz-peaked-spectrumradio sources,” Astronomy and Astrophysics, vol. 329,pp. 845-852, 1998
[17]
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
[18]
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
[19]
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
[20]
I. Owsianik, andJ. E. Conway,“First detection ofhotspot advance in a compact symmetric object” Astron. and Astrophy., vol. 337, pp. 69-79, 1998
[21]
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
[22]
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
[23]
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
[24]
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
[25]
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
Browse journals by subject