相关论文: A method of estimation of the dynamical age of FR …

In this paper, the second in a series investigating FR II radio galaxies at low frequencies, we use LOFAR and VLA observations between 117 and 456 MHz in addition to archival data to determine the dynamics and energetics of two radio…

We present an up-to-date critique of the physical basis for the spectral ageing method. We find that the number of cases where this method may be meaningfully applied to deduce the ages of classical double radio sources is small indeed.…

Continuous injection models of spectral ageing have long been used to determine the age of radio galaxies from their integrated spectrum; however, many questions about their reliability remain unanswered. With various large area surveys…

The broad-bandwidth capabilities of next generation telescopes such as the JVLA mean that the spectrum of any given source varies significantly within the bandwidth of any given observation. Detailed spectral analysis taking this variation…

Multifrequency observations with the GMRT and the VLA are used to determine the spectral breaks in consecutive strips along the lobes of a sample of selected giant radio sources (GRSs) in order to estimate their spectral ages. The maximum…

The dynamical ages of the opposite lobes of selected giant radio sources are estimated using the DYNAGE algorithm of Machalski et al., and compared with their spectral ages estimated and studied by Jamrozy et al. in Paper II. As expected,…

Two frequency observations, mainly at 1.4 and 5 GHz from the VLA, have been used to study spectral variations along the lobes of some nearby low luminosity radio galaxies that constitute a representative sample selected from the B2…

The KDA (Kaiser, Dennett-Thorpe & Alexander, 1997) EXT model, that is, the extension of the KDA model of FR (Faranoff & Riley) II-type source evolution, is applied and confronted with the observational data for selected FR II-type radio…

We compare two temporal properties of classical double radio sources: i) radiative lifetimes of synchrotron-emitting particles and ii) dynamical source ages. We discuss how these can be quite discrepant from one another, rendering use of…

Jets of energetic particles, as seen in FR type-I and FR type-II sources, ejected from the center of Radio-Loud AGN affect the sources surrounding intracluster medium/intergalactic medium. Placing constraints on the age of such sources is…

After a brief introduction to the morphological properties of FRI radio sources, we discuss the possibility that FRI jets are relativistic at their bases and decelerate quickly to non-relativistic velocities. From two-frequency data we…

Due to their steep spectra, low-frequency observations of FR II radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous…

The 'spectral age problem' is our systematic inability to reconcile the maximum cooling time of radiating electrons in the lobes of a radio galaxy with its age as modelled by the dynamical evolution of the lobes. While there are known…

The active galactic nuclei (AGN) lobe radio luminosities modelled in hydrodynamical simulations and most analytical models do not address the redistribution of the electron energies due to adiabatic expansion, synchrotron radiation and…

Stellar age determination for large samples of stars opens new avenues for a broad range of astronomical sciences. While precise stellar ages for evolved stars have been derived from large ground- and space-based stellar surveys, reliable…

The dynamical evolution and radiative properties of luminous radio galaxies and quasars of the FRII type, are well understood. As a result, through the use of detailed modeling of the observed radio emission of such sources, one can…

A 3-dimensional model of the synchrotron emissivity of the cocoons of powerful extragalactic radio sources of type FRII is constructed. Bulk backflow and energy losses of the relativistic electrons, radiative and adiabatic, are…

The time evolution of giant lobe-dominated radio galaxies (with projected linear size D>1 Mpc if H_{0}=50 km/s/Mpc and q_{0}=0.5 is analysed on the basis of dynamical evolution of the entire FRII-type population. Two basic physical…

Determining the energy spectrum of an electron population can give key insights into the underlying physics of a radio source; however, the lack of high resolution, broad-bandwidth observations has left many ambiguities in our understanding…

In order to understand the possible mechanisms of recurrent jet activity in radio galaxies and quasars, which are still unclear, we have identified such sources with a large range of linear sizes (220 $-$ 917 kpc), and hence time scales of…