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Magneto-Active Environments in Pulsar Binaries with the MeerKAT Telescope: I. Pulsar sample and their basic properties

Jaikhomba Singha, Dongzi Li, Marisa Geyer, Maciej Serylak, Federico Abbate, Senate Lekomola, Robert Main, Andrea Possenti, Amanda Weltman

Abstract

Eclipsing pulsar binaries and binaries with a high mass companion are ideal systems for studying and understanding the properties of plasma in magneto-ionic environments. In this work, the first paper of a series, we present MeerKAT observations of three pulsar binaries: the high-mass binary PSR J1740$-$3052, the black widow PSR J2051$-$0827 and the redback PSR J1748$-$2446A (Terzan~5A). With the help of MeerKAT's high-sensitivity polarimetric observations, we characterise the properties of these sources, including the linear/circular polarization, dispersion measure (DM), rotation measure (RM) and scattering time. The two eclipsing millisecond pulsars exhibit strong orbital-phase-dependent propagation effects and we observe $\sim$2 eclipses in these systems during our observations. PSR J1740$-$3052 is a binary system with a 231 d orbital period. The relatively large separation results in a smooth RM variation, enabling us to resolve its variation timescale and constrain the small-scale magnetic structure. A gradual RM variation is observed over $\sim$1500 s, occurring near periastron. This behaviour implies a magnetic spatial scale of $\sim$0.003 AU in the companion wind, assuming a relative velocity of $\sim$250 km s$^{-1}$. The linear polarisation intensity profiles of PSR J2051$-$0827 show shape variations as a function of frequency, with a stronger leading component emerging at lower frequencies. We observe signatures of the propagation effect in the polarisation properties of PSR J1748$-$2446A during eclipse ingress and egress. This could arise from Faraday Conversion or multipath propagation of the pulsar signal and requires detailed analysis.

Magneto-Active Environments in Pulsar Binaries with the MeerKAT Telescope: I. Pulsar sample and their basic properties

Abstract

Eclipsing pulsar binaries and binaries with a high mass companion are ideal systems for studying and understanding the properties of plasma in magneto-ionic environments. In this work, the first paper of a series, we present MeerKAT observations of three pulsar binaries: the high-mass binary PSR J17403052, the black widow PSR J20510827 and the redback PSR J17482446A (Terzan~5A). With the help of MeerKAT's high-sensitivity polarimetric observations, we characterise the properties of these sources, including the linear/circular polarization, dispersion measure (DM), rotation measure (RM) and scattering time. The two eclipsing millisecond pulsars exhibit strong orbital-phase-dependent propagation effects and we observe 2 eclipses in these systems during our observations. PSR J17403052 is a binary system with a 231 d orbital period. The relatively large separation results in a smooth RM variation, enabling us to resolve its variation timescale and constrain the small-scale magnetic structure. A gradual RM variation is observed over 1500 s, occurring near periastron. This behaviour implies a magnetic spatial scale of 0.003 AU in the companion wind, assuming a relative velocity of 250 km s. The linear polarisation intensity profiles of PSR J20510827 show shape variations as a function of frequency, with a stronger leading component emerging at lower frequencies. We observe signatures of the propagation effect in the polarisation properties of PSR J17482446A during eclipse ingress and egress. This could arise from Faraday Conversion or multipath propagation of the pulsar signal and requires detailed analysis.

Paper Structure

This paper contains 7 sections, 7 figures, 1 table.

Table of Contents

  1. Introduction
  2. Observations and Data Reduction
  3. Results and Discussions
  4. PSR J1740$-$3052
  5. PSR J2051$-$0827
  6. PSR J1748$-$2446A
  7. Summary and Future Work

Figures (7)

  • Figure 1: The pulse profile of PSR J1740$-$3052 at different frequency channels for 320 s of sub-integrated time, observed 6 days away from the epoch of periastron. The solid black lines represent the total intensity, the red dashed lines represent linear polarisation and the blue dash-dotted lines represent circular polarisation. There is no visible effect of scatter-broadening at the lower frequency channels of S1-band observations. The pulsar shows very low circular polarisation intensities at all frequency channels.
  • Figure 2: Evolution of total intensity (1st panel/top), linear polarisation intensity (2nd panel), circular polarisation intensity (3rd panel), DM and scattering variation (4th panel) and RM variation (5th panel) as a function of observation time for PSR J1740$-$3052, observed at S1-band with 875 MHz bandwidth the centre frequency of 2405 MHz. There is no visible DM or scattering variation in this pulsar. However, the RM shows a slow variation.
  • Figure 3: Left: The pulse profile of PSR J2051$-$0827 at different frequency channels for 320 s of sub-integrated time, far away from the eclipse region. The solid black lines represent the total intensity, the red dashed lines represent linear polarisation and the blue dash-dotted lines represent circular polarisation. The lower frequency channels have lower linear and circular polarisation intensities. We also see clear scintillation in this pulsar as a function of frequency. Right: Stokes I, Q, U and V as a function of frequency after being corrected for the value of RM. It is seen that the behaviour of Stokes Q and U changes as a function of frequency, with a stronger leading component emerging at lower frequencies, resulting in overall changes in the linear polarisation intensity profiles as a function of frequency.
  • Figure 4: Evolution of total intensity (1st panel/top), linear polarisation intensity (2nd panel), circular polarisation intensity (3rd panel), DM and scattering variation (4th panel) and RM variation (5th panel) as a function of observation time for PSR J2051$-$0827, observed at L-band with 856 MHz bandwidth and 1284 MHz centre frequency. We observe two eclipses during our 4 hrs observation.
  • Figure 5: The pulse profile of PSR J1748$-$2446A at different frequency channels for 320 s of sub-integrated time, far away from the eclipse region. The solid black lines represent the total intensity, the red dashed lines represent linear polarisation and the blue dash-dotted lines represent circular polarisation. The effects of scattering are visible at the lower frequency channels. The linear and circular polarisations are equally strong at all frequency channels.
  • ...and 2 more figures