Detection of decametre-wavelength pulsed radio emission of 40 known pulsarsReport as inadecuate

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1 Institute of Radio Astronomy 2 USN - Unité Scientifique de la Station de Nançay 3 LPC2E - Laboratoire de Physique et Chimie de l-Environnement et de l-Espace 4 LESIA - Laboratoire d-études spatiales et d-instrumentation en astrophysique

Abstract : The study of pulsars at the lowest radio frequencies observable from the ground 10-30 MHz is complicated by strong interstellar dispersion, scattering and ionospheric scintillation, refraction propagation effects, as well as intense Galactic background noise and interference. However, it permits us to measure interstellar plasma parameters the effects of which increase by a power of two to >4 times the wavelength, the spectrum and the pulse profile at low frequencies more accurately. Up to now, only ˜10 pulsars have been successfully detected at these frequencies. The recent upgrade of the receivers at the Ukrainian T-shaped Radio telescope, second modification UTR-2 has increased its sensitivity and motivated a new search for pulsed radio emissions. In this work we carried out a survey of known pulsars with declination above -10°, period >0.1 s and dispersion measure DM < 30 pc cm-3, i.e. a sample of 74 sources. Our goal was either to detect pulsars not recorded before in the decametre range or to identify factors that prevent their detection. As a result, we have detected the radio emission of 40 pulsars, i.e. 55 per cent of the observed sample. For 30 of them, this was a first detection at these frequencies. Parameters of their average profiles have been calculated, including the intrinsic widening of the pulse not due to interstellar scattering with decreasing frequency. Furthermore, two pulsars beyond the selected DM B0138+59 with DM ≈ 35 pc cm-3 and B0525+21 with DM ≈51 pc cm-3 were also detected. Our results indicate that there is still room to detect new transient and pulsed sources with low-frequency observations.

Keywords : methods: data analysis pulsars: general pulsars: individual: PSR B0031−07




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