Related papers: Spectral ageing: a new age perspective
We propose a new approach in determining ages of FR II type radio sources. We apply the assumed dynamical model of Kaiser et al. (1997) to a number of FR II type radio galaxies observed at different radio frequencies, and fit - for each…
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…
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…
I present a brief overview of observational, modeling and theoretical issues related to ageing calculations based on spectral steepening. These include problems such as inhomogeneous magnetic fields, diffusion of relativistic particles,…
This paper deals with the spectral ageing study of a representative sample of compact symmetric objects (CSOs) and compact steep spectrum (CSS) sources. Observations reveal a distinctive high-frequency steepening of the radio spectra of…
An algorithm is presented which generates pairs of oscillatory random time series which have identical periodograms but differ in the number of oscillations. This result indicate the intrinsic limitations of spectral methods when it comes…
Beginning with a historical account of the spectral classification, its refinement through additional criteria is presented. The line strengths and ratios used in two dimensional classifications of each spectral class are described. A…
Recent studies on the phenomenology of ageing in certain many-particle systems which are at a critical point of their non-equilibrium steady-states, are reviewed. Examples include the contact process, the parity-conserving…
Age estimation is a technique for predicting human ages from digital facial images, which analyzes a person's face image and estimates his/her age based on the year measure. Nowadays, intelligent age estimation and age synthesis have become…
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…
Comparing different age estimation methods poses a challenge due to the unreliability of published results stemming from inconsistencies in the benchmarking process. Previous studies have reported continuous performance improvements over…
Age estimation from images can be used in many practical scenes. Most of the previous works targeted on the estimation from images in which only one face exists. Also, most of the open datasets for age estimation contain images like that.…
The well-known age-metallicity-attenuation degeneracy does not permit unique and good estimates of basic parameters of stars and stellar populations. The effects of dust can be avoided using spectral line indices, but current methods have…
Much progress has been achieved in the age-dating of old stellar systems, and even of individual stars in the field, in the more than sixty years since the evolution of low-mass stars was first correctly described. In this paper, I provide…
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,…
It is well known that, when analyzed at the light of current synthesis model predictions, variations in the physical properties of single stellar populations (e.g. age, metallicity, initial mass function, element abundance ratios) may have…
Human age estimation has attracted increasing researches due to its wide applicability in such as security monitoring and advertisement recommendation. Although a variety of methods have been proposed, most of them focus only on the…
To date, Galactic Astronomy has largely concerned itself with astrophysical processes, and with the locations, space motions and compositions of objects. Consider, for example, the elucidation of the components of the Galaxy over the past…
Age dating starbursts is an exercise with many caveats. We attempt to summarise a discussion session that was lead along a rather optimistic guideline: the aim was to highlight that current age estimates, despite undeniable uncertainties,…