First Implementation of the Fast Radiometry Mode at RATAN-600 for Studying Pulsar Radiation

Trushkin S. A., Tsybulev P. G., Bursov N. N., Nizhelskij N. A.

In 2018, we implemented the mode of fast radiometry with a discretization interval from 60 to 490 μs at the 4.7 GHz sensitive radiometer for the first time. This mode is necessary for detecting and searching for fast radio bursts (FRB) from the characteristic delay of the arrival time of a burst due to the interstellar and intergalactic dispersion.

Western Sector of RATAN-600 and three beams at a frequency of 4.7 GHz

During purpose measurements, single impulses from the nearby pulsar PSR0329+54 in the Southern Sector and the young pulsar PSR0534+22 in the Crab Nebula in the Western Sector of the RATAN-600 radio telescope were detected for the first time ever. In the pilot survey of fast radio bursts in the Western Sector, we found five single giant impulses (GI) from the 33-millisecond pulsar PSR0534+22 in the Crab Nebula at a 3-beam 4-channel complex in the frequency band 4.2–4.8 GHz. On June 30, 2018, the flow of GIs (~1 ms) exceeded 150 Jy, while the average impulse flows are below 10 mJy. From the time shift of the impulse arrival, the dispersion was measured: DM = 57±1 pc/cm³ which is in good agreement with previous measurements.
(a) Actual recording (8 ms) of the passage of a giant impulse in the Crab with an impulse-arrival delay with the increased wavelength. (b) Giant impulse in the full frequency band.

The GI found in the observations on October 2, 2018 consisted of two sub-impulses with a flow of about 8 and 4 Jy and a duration of 300 µs separated by 400 µs.
Dependence between the arrival time of four giant impulses and the frequency in comparison with the calculated dependence for the known dispersion.

It follows that the area of impulse radiation has a size of about 100 km, and its brightness temperature exceeds 10²⁵ K. It was planned to use the fast radiometry mode in the “source-tracking” mode behind the source for 100–200 s which will allow us to determine the average flows and impulse profiles of pulsars at 4.7 GHz. On the other hand, the search for single impulses subject to cosmic dispersion—fast radio bursts—continues on the newly created antenna-radiometric complex.
Average impulse profiles of the pulsar PSR0329+54 at 2.3 and 4.7 GHz as observed in June 2017.

Contact person: Trushkin S.A., Head of Radio Astrophysics Laboratory, SAO RAS.