SEARCH FOR LOW-INTENSITY INTERFERENCE AND DISTRIBUTIONS OF TRANSIENT SIGNALS’ CHARACTERISTICS IN THE DATA OF DECAMETER SURVEY OF NORTHERN SKY

Abstract

Purpose: The most challenging problem of transient signal research is to prove their cosmic origin. There is no radio telescope at decameter wavelengths, which has an effective area (i.e. instantaneous sensitivity) at least close to the UTR-2 radio telescope parameters. This fact excludes the possibility of confirming the cosmic origin of detected low-intensity signals at some other independent radio telescope of this frequency range. Therefore, it is impossible to overestimate the importance of carrying out all possible kinds of tests to check the probable interference origin of candidate signals. In this work we analyze the distributions of detected transient signals parameters and search for possible low-intensity interference in the decameter pulsars and transient sources survey of the northern sky observational data. Design/methodology/approach: Search for interference caused by ionospheric plasma-related scintillations, with a time-frequency response symmetrical to signals with dispersion delay induced by interstellar medium. Findings: Distributions of signal-to-noise ratios and dispersion measures appear to be very different for transient signals detected in the survey and the hypothetical interference with the same absolute value of shift in arrival time between a lower and a higher frequency, but its opposite sign. This supports the hypothesis of the transient signals detected in the survey being generated by cosmic radio sources. Conclusions: Broadening of radio emission cone of various types of neutron stars along with high angular and temporal scattering at decameter wavelengths could explain the large number of individual signals at unique dispersion measures, and, hence, a large number of transient emission sources.

Keywords

• survey
• single pulse
• radio frequency interference
• dispersion measure
• scintillations
• decameter wavelengths