The spectral index-flux density relation for extragalactic radio sources selected at metre and decametre wavelengths

Dabhade, Pratik; Gopal-Krishna
Referencia bibliográfica

Astronomy and Astrophysics

Fecha de publicación:
Número de autores
Número de autores del IAC
Número de citas
Número de citas referidas
We use the recent releases of sensitive VLA/LOFAR large-area surveys at 340 MHz and 54 MHz, in conjunction with the 1.4 GHz NVSS, to accurately determine the `spectral index-flux density relation' (α − S) for extragalactic radio sources selected at metre and decametre wavelengths, with the latter explored for the first time. This newly determined α − S340 MHz relation shows a progressive flattening of αmedian towards lower flux densities, starting from its steepest value (peak) occurring near S340 MHz ∼ 1 − 2 Jy. This resolves the controversy extant in the literature since the 1980s. The α − S54 MHz relation also shows a spectral index flattening with decreasing flux density which is, however, significantly milder and the relation less sharply peaked than that found at 340 MHz. A possible reason for the difference could be that the 54 MHz sample has a distinctly stronger and more conspicuous presence ( at ∼20% level) of very steep spectrum sources having α541400 < −1.3, most of which are probably associated with clusters of galaxies.
Proyectos relacionados
Project Image
Centros de Galaxias a Escalas de Parsecs y Técnicas de Alta Resolución Espacial

Proyecto enfocado al estudio en el IR del núcleo de las galaxias más cercanas con resoluciones espaciales en el rango de 1 a 10 pc. Estas resoluciones espaciales, accesibles con los grandes telescopios de tierra usando técnicas frontera de observación, son por primera vez comparables a las que se obtienen rutinariamente con HST en el óptico y VLBI

Prieto Escudero