Related papers: Spectral variability in faint high frequency peake…
We investigate the spectral characteristics of 51 candidate High Frequency Peakers (HFPs), from the ``bright'' HFP sample, in order to determine the nature of each object, and to obtain a smaller sample of genuine young radio sources.…
We present new, simultaneous, multifrequency observations of 45 out of the 55 candidate High Frequency Peakers (HFP) selected by Dallacasa et al. (2000), carried out 3 to 4 years after a first set of observations. Our sub-sample consists of…
A sample of high-frequency peaker (HFP) candidates was formed from the AT20G catalog radio sources with spectral indices of the optically thick emission region $\alpha_{below}$ exceeding +0.5. A study of the spectral properties of the…
A sample of 123 radio sources that exhibit significant variations at 1.4 GHz on a seven year base-line has been created using FIRST VLA B-array data from 1995 and 2002 on a strip at dec=0 near the south Galactic cap. This sample spans the…
Aims: The ``bright'' High Frequency Peakers (HFPs) sample is a mixture of blazars and intrinsically small and young radio sources. We investigate the polarimetric characteristics of 45 High Frequency Peakers, from the ``bright'' HFP sample,…
We present CCD observations of 13 objects from a complete sample of 55 bright High Frequency Peaker (HFP) radio sources, and provide optical identification for 12 of them. Images in R and V filters have been used to derive some additional…
Spectral variability of radio sources encodes information about the conditions of intervening media, source structure, and emission processes. With new low-frequency radio interferometers observing over wide fractional bandwidths, studies…
Here we present a sample of sources with convex radio spectra peaking at frequencies above a few GHz. We call these radio sources High Frequency Peakers (HFPs). This sample extends to higher turnover frequencies than the samples of Compact…
We present the results of second epoch simultaneous multifrequency observations of 45 sources out of the 55 in the sample of High Frequency Peakers (HFP) by Dallacasa et al. (2000). Seven of the stellar sources (i.e. 16% of the total number…
The incidence of young but fading radio sources provides important information on the life cycle of radio emission in radio-loud active galactic nuclei. Despite its importance for constraining the models of radio source evolution, there are…
We investigate the parsec-scale structure of 17 high frequency peaking radio sources from the faint HFP sample. VLBA observations were carried out at two adjacent frequencies, 8.4 and 15.3 GHz, both in the optically-thin part of the…
We report results on multi-epoch Very Large Array (VLA) and pc-scale Very Long Baseline Array (VLBA) observations of candidate compact symmetric objects (CSOs) from the faint sample of high frequency peakers. New VLBA observations could…
Characterising spectral variability of radio sources is a technique that offers the ability to determine the astrophysics of the intervening media, source structure, emission and absorption processes. We present broadband (0.072--10 GHz)…
Using three epochs of VLA observations of the Galactic Plane in the first quadrant taken ~15 years apart, we have conducted a search for a population of variable Galactic radio emitters in the flux density range 1-100 mJy at 6 cm. We find…
Multifrequency Very Long Baseline Array (VLBA) observations were performed to study the radio morphology and the synchrotron spectra of four high frequency peaking radio sources. They are resolved in several compact components and the radio…
A wide range of phenomena, from explosive transients to active galactic nuclei, exhibit variability at radio wavelengths on timescales of a few years. Characterizing the rate and scale of variability in the radio sky can provide keen…
A comprehensive search for variable and transient radio sources has been conducted using ~55,000 snapshot images of the FIRST survey. We present an analysis leading to the discovery of 1,627 variable and transient objects down to mJy levels…
The mJy variable extragalactic radio sky is known to be broadly non-changing with approximately $3\%$ of persistent radio sources exhibiting variability which is largely AGN-related. In the faint (<mJy) flux density regime, it is widely…
Compact steep-spectrum radio sources and giga-hertz peaked spectrum radio sources (CSS/GPS) are generally considered to be mostly young radio sources. In recent years we studied at many wavelengths a sample of these objects selected from…
Radio sources with steep and ultra-steep spectra, identified through a series of surveys of the Cold experiment using the RATAN-600 radio telescope, formed the basis of the Big Trio program aimed at discovering distant radio galaxies. With…