Jiamusi pulsar observations^★

II. Scintillations of ten pulsars

¹ National Astronomical Observatories, Chinese Academy of Sciences, Jia-20 Datun Road, Chaoyang District, Beijing 100101, PR China
e-mail: pfwang@nao.cas.cn, hjl@nao.cas.cn
² The State Key Laboratory of Astronautic Dynamics, Xi’an, Shaanxi 710043, PR China
³ Jiamusi Deep Space Station, China Xi’an Satellite Control Center, Jiamusi, Heilongjiang 154002, PR China
⁴ School of Astronomy, University of Chinese Academy of Sciences, Beijing 100049, PR China
⁵ CAS Key Laboratory of FAST, NAOC, Chinese Academy of Sciences, Beijing 100101, PR China

Received: 12 April 2018
Accepted: 17 August 2018

Abstract

Context. Pulsars scintillate. Dynamic spectra show brightness variation of pulsars in the time and frequency domain. Secondary spectra demonstrate the distribution of fluctuation power in the dynamic spectra.

Aims. Dynamic spectra strongly depend on observational frequencies, but were often observed at frequencies lower than 1.5 GHz. Scintillation observations at higher frequencies help to constrain the turbulence feature of the interstellar medium over a wide frequency range and can detect the scintillations of more distant pulsars.

Methods. Ten pulsars were observed at 2250 MHz (S-band) with the Jiamusi 66 m telescope to study their scintillations. Their dynamic spectra were first obtained, from which the decorrelation bandwidths and timescales of diffractive scintillation were then derived by autocorrelation. Secondary spectra were calculated by forming the Fourier power spectra of the dynamic spectra.

Results. Most of the newly obtained dynamic spectra are at the highest frequency or have the longest time span of any published data for these pulsars. For PSRs B0540 + 23, B2324 + 60, and B2351 + 61, these were the first dynamic spectra ever reported. The frequency dependence of the scintillation parameters indicates that the intervening medium can rarely be ideally turbulent with a Kolmogorov spectrum. The thin-screen model worked well at S-band for the scintillation of PSR B1933 + 16. Parabolic arcs were detected in the secondary spectra of three pulsars, PSRs B0355 + 54, B0540 + 23, and B2154 + 40, all of which were asymmetrically distributed. The inverted arclets of PSR B0355 + 54 were seen to evolve along the main parabola within a continuous observing session of 12 h, from which the angular velocity of the pulsar was estimated. This was consistent with the measurement by very long baseline interferometry.