2008/02/05 by V. Safouris, R. Subrahmanyan, G. V. Bicknell +2 · 38 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysical jet #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Galaxy #Hotspot (geology) #Jet (fluid) #Mach number #Polarization (electrochemistry) #Radio galaxy #Shock wave #Supersonic speed #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2008.12975.x
published in Monthly Notices of the Royal Astronomical Society 385(4), 2117-2135 (Oxford University Press) · 26 pages including 1 table and 16 figures. To appear in MNRAS
arxiv created 2008/02/05 · openalex publication_date 2008/02/27 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Sensitive, high-resolution images of the double–double radio galaxy PKS B1545−321 reveal detailed structure, which we interpret in light of previous work on the interaction of restarted jets with pre-existing relict cocoons. We have also examined the spectral and polarization properties of the source, the colour distribution in the optical host and the environment of this galaxy in order to understand its physical evolution. We propose that the restarted jets generate narrow bow shocks and that the inner lobes are a mixture of cocoon plasma re-accelerated at the bow shock and new jet material re-accelerated at the termination shock. The dynamics of the restarted jets implies that their hotspots advance at mildly relativistic speeds with external Mach numbers of at least 5. The existence of supersonic hotspot Mach numbers and bright inner lobes is the result of entrainment causing a reduction in the sound speed of the pre-existing cocoon. The interruption to jet activity in PKS B1545−321 has been brief – lasting less than a few per cent of the lifetime ∼(0.3–2) × 108yr of the giant radio source. The host galaxy is located at the boundary of a large-scale filamentary structure, and shows blue patches in colour distribution indicative of a recent merger, which may have triggered the Mpc-scale radio galaxy.