Decametric survey of discrete sources in the northern sky

Braude, S. Ya.; Megn, A. V.; Sokolov, K. P.; Tkachenko, A. P.; Sharykin, N. K.

doi:10.1007/bf00640035

Cited by 27 publications

(11 citation statements)

References 9 publications

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“…However, because the 4C survey has a resolution of 11.5 arcmin, the flux density of the nearby sources will blend with that of J0311+0507, we discarded the match. We, for the same reason, discarded the matches to Bursov (1996) (at 0.96,2.3,3.94 and 7.69 GHz), Parijskij et al (2010) (at 0.5, 1.4 and 3.94 GHz), Parijskij et al (1996) (at 1.425 GHz), Pariiskii et al (1992) (at 3.945 GHz) and Braude et al (1979) (at 16.7 MHz).…”

Section: J0311+0507mentioning

confidence: 99%

Radio spectra of bright compact sources at z>4.5

Coppejans

Velzen

Intema

et al. 2017

Mon. Not. R. Astron. Soc.

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High-redshift quasars are important to study galaxy and active galactic nuclei (AGN) evolution, test cosmological models, and study supermassive black hole growth. Optical searches for high-redshift sources have been very successful, but radio searches are not hampered by dust obscuration and should be more effective at finding sources at even higher redshifts. Identifying high-redshift sources based on radio data is, however, not trivial. Here we report on new multi-frequency Giant Metrewave Radio Telescope (GMRT) observations of eight z > 4.5 sources previously studied at high angular resolution with very long baseline interferometry (VLBI). Combining these observations with those from the literature, we construct broad-band radio spectra of all 30 z > 4.5 sources that have been observed with VLBI. In the sample we found flat, steep and peaked spectra in approximately equal proportions. Despite several selection effects, we conclude that the z > 4.5 VLBI (and likely also non-VLBI) sources have diverse spectra and that only about a quarter of the sources in the sample have flat spectra. Previously, the majority of high-redshift radio sources were identified based on their ultra-steep spectra (USS). Recently a new method has been proposed to identify these objects based on their megahertz-peaked spectra (MPS). Neither method would have identified more than 18 per cent of the high-redshift sources in this sample. More effective methods are necessary to reliably identify complete samples of high-redshift sources based on radio data.

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Section: J0311+0507mentioning

confidence: 99%

Radio spectra of bright compact sources at z>4.5

Coppejans

Velzen

Intema

et al. 2017

Mon. Not. R. Astron. Soc.

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“…From the UTR-2 catalogue (Braude et al, 1978(Braude et al, , 1979(Braude et al, , 1981a(Braude et al, , 1981b(Braude et al, , 2003 we have formed sample of radio sources with steep spectrum including objects with linear steep spectrum (S-type) and spectrum with low-frequency steepness after a break (C+ type). Within the declination ranges from -13 to +20 degrees and from 30 to 40 degrees of the UTR-2 catalogue we have identified 78 galaxies and 55 quasars with linear steep spectrum (S-type) and 52 galaxies and 36 quasars with break steep spectrum (C+type) (with flux density at 25 MHz S 25 > 10 Jy and spectral index larger 1).…”

Section: Luminosity -Linear Size Relation For Powerful Giant Sourcesmentioning

confidence: 99%

Luminosity-Linear Size Relation for Galaxies and Quasars With Steep Radio Spectrum

Miroshnichenko

2015

OAP

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Our data for sources with steep radio spectrum, detected with radio telescope UTR-2 at the decametre band give evidence on the great luminosities, linear sizes, characteristic ages of these objects. In connection with such peculiarities, we examine the luminosity-linear size relation of galaxies and quasars with steep radio spectrum at the decametre band. It turned out, that this relation has similar trends for considered radio sources with linear steep spectrum and break steep spectrum. Also we presented the luminosity ratio-linear size relation at different frequency ranges. We discuss the obtained evolution relations for galaxies and quasars with steep low-frequency radio spectrum.

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“…This spectrum steepness may be reflection of the specific long evolution of given sources. As we have obtained (Miroshnichenko , 2010(Miroshnichenko , , 2012(Miroshnichenko , , 2013(Miroshnichenko , , 2015 the properties of steep-spectrum sources from the UTR-2 catalogue (Braude et al, 1978(Braude et al, , 1979(Braude et al, , 1981a(Braude et al, , 1981b(Braude et al, , 2003 are peculiar: all galaxies and quasars with steep radio spectrum have high luminosity (the monochromatic radio luminosity at 25 MHz is ~ 10 28 W/(Hz ster)), giant linear size of radio image ( ~ Mpc), great characteristic age ( ~ 10 8 years). Giant size of radio structure of these sources is connected with great extent of jets emanated from active nuclei of objects.…”

Section: Introductionmentioning

confidence: 81%

“…The catalogue UTR-2 is the catalogue of extragalactic radio sources detected at frequencies 10, 12.6, 14.7, 16.7, 20 and 25 MHz during the northern sky survey at the largest over the world Ukrainian radio telescope UTR-2 in the decametre band (Braude et al, 1978, 1979, 1981, Konovalenko et al, 2016. Radio spectra of detected sources in UTR-2 catalogue had been derived at the range 10 -1400 MHz with connection of more high-frequency data and had shown that near 30 per cent of low-frequency spectra are steep (the value of spectral index was greater than 1) (Braude et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Jet propagation velocity and environment density of giant radio sources with steep radio spectrum

Miroshnichenko

2019

Astrophys Space Sci

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Before we have determined that giant radio structure is typical for steep-spectrum sources detected with Ukrainian T-shaped Radio Telescope of model 2 (UTR-2). To estimate the jet propagation velocity and environment density of giant radio sources we consider the sample of galaxies and quasars with steep radio spectrum compiled from two regions of UTR-2 catalogue. The value of velocity of jet propagation is obtained from our estimates of linear size of radio structure and characteristic age of a source. We use the obtained values of jet propagation for the estimates of density of jet environment, that is, density of environment at galaxies and quasars outskirts. We have derived that values of jet propagation velocities of examined sources are ~ 10 9 cm/s. The positive correlation of jet velocity and redshift of source is displayed in our sample. On the assumption of equality of jet luminosity and corresponding kinetic luminosity we estimate the density of jet environment (radio structure environment) for galaxies (10 -26 g/cm 3 -10 -27 g/cm 3 ) and quasars (10 -28 g/cm 3 ). Considered steep-spectrum galaxies and quasars display strong evolution of jet propagation velocity and jet environment density. Properties of giant steep-spectrum sources are in accordance with conception of long evolution of powerful sources. The steep low-frequency spectra may be as markers of giant radio structures of galaxies and quasars.

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Decametric survey of discrete sources in the northern sky

Cited by 27 publications

References 9 publications

Radio spectra of bright compact sources at z>4.5

Radio spectra of bright compact sources at z>4.5

Luminosity-Linear Size Relation for Galaxies and Quasars With Steep Radio Spectrum

Jet propagation velocity and environment density of giant radio sources with steep radio spectrum

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