A study of the spectral and structural asymmetries in five giant radio sources
Akash Pirya
Centro de Radioastronomía y Astrofísica (CRyA), Morelia Campus, UNAM, Mexico September 22, 2014 List of Collaborators
Saikia, D. J., CCU & NCRA-TIFR, India Singh, M., ARIES, India Chandola, H. C., KU, India
Jamrozy, M., ASTRON, Netherland Gonazalez, R., CRyA, Mexico Verkhodonova, O., SAO, Russia
Chandola, Y., NAOC, China Joshi, R., IUCAA, India Katarzyna Wojtaczka, ASTRON, Netherland Katarzyna Janda, ASTRON, Netherland Khabibullina, M., SAO, Russia Medhi, B. J., ARIES, India Summary
Radio Galaxies Asymmetries in radio sources – jet, hotspots, environments..... Sample of Giant Radio Sources - asymmetric Five giant radio sources – GMRT & VLA Discussion
09/22/14 Radio Galaxies : active galaxy that are very bright at radio wavelengths (up to 1046 W between 10 MHz and 100 GHz). Jets Bridge Lobe
Hotspot
Core Lobe Hotspot Giant Radio Galaxies : a class of radio sources on the megaparsec scale.
09/22/14 Hotspot
Jet
Core
Lobe
Hotspot
09/22/14FRII FRI Examples of Radio Galaxies
FR II FR I
3C 296 3C 219
FR dichotomy (HYMORS) 3C 16 4C 14.27
09/22/14 Asymmetries in RGs/GRGs jet asymmetry in the 3C 215 oppositely-directed lobes. structural and spectral asymmetries of the oppositely-directed components. NGC 6251 intrinsic and environmental asymmetries.
3C 28
09/22/14 Groups and cluster of galaxies
Galaxy groups and clusters are the largest known massive and gravitationally bound systems in the universe to explain the large scale structure. Earlier studies show that the host galaxies of the radio sources are found in a galaxy cluster (Blanton 2000, 2001 and 2003, Belsole et al. 2007, Venturi et al. 2007, Wing & Blanton 2011), specially FR I in richer groups in comparison to FR II sources (Miller et al. 1999 and Zirbel 1997). Zirbel (1997) suggested that FR II type of radio sources inhibit much richer group of galaxies at high redshift (z > 0.5) and have different type of environment at high and low redshifts.
09/22/14 Environmental Asymmetry
Effect of nearby galaxy distributions on the structures of source - Interaction of jets with the medium - affected by filaments, sheets or voids
Chen et al. 2011
Chen et al. 2012
09/22/14 Pirya et al. 2014a, submitted
09/22/14 Pirya et al. 2012 Saripalli et al. 1986 J0503-286
Subrahmanyan et al. 2009 09/22/14 Sample of GRSs (asymmetric)
Saikia D.J., Jamrozy M., Pirya A., et al. 2014, to be submitted 09/22/14 09/22/14 Five asymmetric giant sources
Selected from Lara et al. 2001a S (1.4 GHz) ~ > 100 mJy R ~ > 4 GMRT ~ 235 MHz to 610 MHz VLA ~ archival data
09/22/14 09/22/14 GRG J0318+584
Peak surface brightness ratio ~ 6 to 13 Size ~ 1.5 Mpc
09/22/14 Spectral index ~ 0.78, 1.09, 0.91 High frequency peaker with spectral index 0.42 from 1.4 GHz to 10.5 GHz
09/22/14 GRG J0949+732
Peak surface brightness ~ 5 to 8 09/22/14 Spectral index ~ 0.81, 0.84
09/22/14 GRG J1211+743
Ratio ~ 5 to 9 Size ~ 1 Mpc 09/22/14 Pirya et al. 2011 Spectral index ~ 0.84, 1.00, 0.88, 0.71
09/22/14 GRG J1918+742
Pirya et al. 2011 Ratio ~ 12 to 15 Size ~ 1.3 Mpc
09/22/14 Spectral index ~ 0.97, 0.77, 1.05
09/22/14 GRG J2042+751
Associated with quasar, 1.2 Mpc ~ 13 to 21 One sided jet towards south (Riley & Warner, 1990)
09/22/14 Spectral index ~ 0.62, 0.96, 0.82
09/22/14 Conclusion.... The peak brightness ratios likely to be intrinsic rather than due to the effects of relativistic motion. The spectra of the components with a prominent peak or hot- spot tend to be flatter, as for the smaller-sized sources. The absence of significant steepening is possibly due to re- acceleration of particles in these components, and a difference in the variation of spectral indices on opposite sides of the nucleus suggests an intrinsic asymmetry either in the collimation or interaction of the jets with their environment. The components with prominent hot-spots, besides exhibiting have flatter spectra, show steepening of the spectral index with distance from the hot-spot, as is usually seen in FRII radio sources.
09/22/14 Thanks
09/22/14 Formation of Radio Galaxies Particles are collimated into two oppositely directed relativistic beams:jets (twin beam model), carry high energetics particles into lobes Jet interaction with IGM, Plasma Jets mix with medium and release energy Radiated energy (hotspots) while Some amount accelerates particle Jet pressure push shock front away from the core leaving behind plasma spread out behind it, the cocoon structure Later jet activity stops, leaving a fading, slowly 09/22/14remnant lobe