Natalia V. Verkhodanova

Steep-spectrum UTR sources in FIRST survey

Abstract In an attempt to find further candidates for high-redshift radio galaxies, we searched the UTR-2 catalogue of decametric radio sources for steep-spectrum (SS) objects (α ≤ –1.1, S ∼ v α). Radio counterparts and radio continuum spectra were prepared using the CATS database of radio source catalogues. High-resolution images of SS sources were extracted from the FIRST 1.4 GHz survey, yielding accurate positions and sizes for 43 SS sources. The search for optical counterparts from the APM (object) and DSS (image) databases, as well as infrared and X-ray identifications of these UTR sources are in progress. Two examples are shown.

USS radio sources from the UTR-2 survey

Abstract We searched for radio counterparts to the ∼ 1800 decametric radio sources from the UTR-2 source catalog. Using the CATS database we established radio continuum spectra fur these sources and present preliminary results for a selection of 23 ultra-steep spectrum (USS) sources with spectral index α ≤ -1.2 (S ∼ v α) and accurate positions from FIRST.

Radio spectra and nvss maps of decametric sources

We constructed radio spectra for ∼1400 UTR-2 sources and find that 46% of them have concave curvature. Inspection of NVSS maps of 700 UTR sources suggests that half of all UTR sources are either blends of two or more sources or have an ultra-steep spectrum (USS). The fraction of compact USS sources in UTR may be near 10%. Using NVSS and the Digitized Sky Survey(s) we expect to double the UTR optical identification rate from currently ∼19%.

Radio-optical Identification of Very-Steep Spectrum Radio Sources from the UTR-2 Catalogue

We used radio source catalogues accessible from the CATS database to establish radio continuum spectra for decametric radio sources in the UTR-2 catalogue. In an attempt to find further candidates for high-redshift radio galaxies, we searched the FIRST and NVSS surveys for counterparts of a sample of UTR sources with ultra-steep radio spectra (USS, α ≤ −1.2, S ∼ v α ). We derived accurate positions and sizes for 23 of these USS sources. The search for optical counterparts from the APM (object) and DSS (image) databases, as well as infrared and X—ray identifications of these UTR sources are in progress.

System to Estimate Ages and Redshifts for Radio Galaxies

The system allowing a user to operate with simulated curves of spectral energy distribution (SED) and to estimate ages and redshifts by photometric data at server {\bf this http URL} is described.