BRIGHTNESS TEMPERATURE AND SPECTRAL INDEX OF EXTRAGALACTIC BACKGROUND AT DECAMETER WAVELENGTHS

DOI: https://doi.org/10.15407/rpra20.03.204

N. M. Vasilenko, M. A. Sidorchuk

Abstract


The radio maps of distributed low-frequency radio emission for vast areas of Northern Celestial Hemisphere, including the area near the minimum of galactic radiation (42º<δ200<45º, 7h45m200<8h35m), were constructed based on the Northern sky survey with the UTR-2 world-largest decameter wave radio telescope. The two-temperature dependence of the background radiation brightness temperature within 12.6 to 25 MHz is built for different frequency pairs of this range for the same coordinates (ТТ plots). This allows to identify the differential emission spectrum of the Galaxy halo in this direction, whose spectral index is βG =2.81±0.03. In addition, the ТТ plots multi-frequency technique provided an opportunity to determine the brightness temperatures of the isotropic extragalactic background radiation at decameter wavelength range, whose values were (60±10.0), (41.7±6.0), (30.6±4.2), (19.5±3.6) and (11.6±10.0) kK at 12.6, 14.7, 16.7, 20, and 25 MHz, respectively, with the spectral index βM =2.41±0.1. Metagalaxy contributed to about 70 % of the total emission at all frequencies in this direction.

Key words: metagalactic background, ТТ plots, spectral index, decameter wavelengths

Manuscript submitted 13.05.2015

Radio phys. radio astron. 2015, 20(3): 205-215


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Keywords


metagalactic background; Т–Т plots; spectral index; decameter wavelengths

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