The Chinese pulsar timing array data release I

Polarimetry for 56 millisecond pulsars

¹ Department of Astronomy, School of Physics, Peking University, Beijing 100871, P.R. China
² National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, P.R. China
³ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, P.R. China
⁴ Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Sciences, Beijing 100101, P.R. China
⁵ Beijing Laser Acceleration Innovation Center, Huairou, Beijing 101400, P. R. China
⁶ Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, P.R. China
⁷ Hellenic Open University, School of Science and Technology, 26335 Patras, Greece
⁸ Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, 830011 Xinjiang, P.R. China
⁹ Yunnan Observatories, Chinese Academy of Sciences, Kunming, 650216 Yunnan, P.R. China
¹⁰ Institute of Optoelectronic Technology, Lishui University, Lishui, Zhejiang 323000, P.R. China
¹¹ National Time Service Center, Chinese Academy Of Sciences, Xi’an 710600, P.R. China
¹² State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, P.R. China

^⋆ Corresponding authors; astroxjw@pku.edu.cn; jiangjinchen@bao.ac.cn; hengxu@bao.ac.cn

Received: 11 November 2024
Accepted: 30 January 2025

Abstract

We present polarization pulse profiles for 56 millisecond pulsars (MSPs) monitored by the Chinese Pulsar Timing Array (CPTA) collaboration using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The observations centered at 1.25 GHz with a raw bandwidth of 500 MHz. Due to the high sensitivity (∼16 K/Jy) of the FAST telescope and our long integration time, the high signal-to-noise ratio polarization profiles show features hardly detected before. Among 56 pulsars, the polarization profiles of PSRs J0406+3039, J1327+3423, and J2022+2534 were not previously reported. 80% of MSPs in the sample show weak components below 3% of peak flux, 25% of pulsars show interpulse-like structures, and most pulsars show linear polarization position angle jumps. Six pulsars seem to be emitting for full rotation phase, with another thirteen pulsars being good candidates for such a 360° radiator. We find that the distribution of the polarization percentage in our sample is compatible with the normal pulsar distribution. Our detailed evaluation of the MSP polarization properties suggests that the wave propagation effects in the pulsar magnetosphere are important in shaping the MSP polarization pulse profiles.