Radio quiet, please! – protecting radio astronomy from interference

Radio Frequency Interference Mitigation in Radio Astronomy

Radio Detection of Radio-quiet Galaxies

We investigate the radio emission of ∼ 185,000 quiescent (optically unclassifiable) galaxies selected from the Sloan Digital Sky Survey (SDSS). By median-stacking FIRST cutouts centered on the optically-selected sources, we are able to reach flux densities down to the 10s of μJy. The quiescent galaxy sample is composed of two subgroups inhabiting vastly different regimes: those targeted for the...

The radio properties of radio-quiet quasars

Although radio-quiet quasars (RQQs) constitute > ∼ 90% of optically-identified quasar samples their radio properties are only poorly understood. In this paper we present the results of a multi-frequency VLA study of 27 low-redshift RQQs. We detect radio emission from 20 objects, half of which are unresolved (≤ 0.24). In cases where significant structure can be resolved, double, triple and linea...

Radio Variability of Radio Quiet and Radio Loud Quasars

The majority of quasars are weak in their radio emission, with flux densities comparable to those in the optical, and energies far lower. A small fraction, about 10%, are hundreds to thousands of times stronger in the radio. Conventional wisdom holds that there are two classes of quasars, the radio quiets and radio louds, with a deficit of sources having intermediate power. Are there really two

Impact of Cognitive Radio on Radio Astronomy

The introduction of new communication techniques requires an increase in the efficiency of spectrum usage. Cognitive radio is one of the new techniques that fosters spectrum efficiency by using unoccupied frequency spectrum for communications. However, cognitive radio will increase the transmission power density and cause an increasing level of Radio Frequency Interference (RFI), which may impa...