A single pulse study of PSR J1022+1001

Abstract

Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we have recorded ∼ 10 5 single pulses from PSR J1022+1001. We studied the polarization properties, their energy distribution and their times of arrival. This is only possible with the high sensitivity available using FAST. There is no indication that PSR J1022+1001 exhibits giant pulse, nulling or traditional mode changing phenomena. The energy in the leading and trailing components of the integrated profile is shown to be correlated. The degree of both linear and circular polarization increases with the pulse flux density for individual pulses. Our data indicates that pulse jitter leads to an excess noise in the timing residuals of 67 ns when scaled to one hour, which is consistent with Liu et al. (2015). We have unsuccessfully trialled various methods to improve timing precision through the selection of specific single pulses. Our work demonstrates that FAST can detect individual pulses from pulsars that are observed in order to detect and study gravitational waves. This capability enables detailed studies, and parameterisation, of the noise processes that affect the sensitivity of a pulsar timing array.

Single-pulse studies of three millisecond pulsars

“…Therefore the timing precision of this pulsar may be improved if integrated profiles that are used to generate TOAs are created by including only the brightest pulses. We note that previous studies have found that selective timing does not yield a significant improvement in timing (Osłowski et al 2014;Feng et al 2020). The first of these studies reported reduced 𝜒 2 of the timing residuals when selectively integrating only weaker pulses, as well as a minor improvement to timing when using brighter pulses.…”

“…(2014) value of 290 ± 15 ns and 269 ± 4 ns of Lam et al (2019) but higher than the 67 ± 9 reported by Feng et al (2020) or ≈ 700 ns for 1-min integration (≈ 90 ns for one hour) reported by Liu et al (2015) at 1.38 GHz. The level of jitter at 4.5 GHz, scaled to one hour, is 301±22 ns, which is higher than that at 1.38 GHz.…”

“…The jitter levels (𝜎 𝑗 ) we find are consistent for PSRs J1022+1002 (Shannon et al 2014;Lam et al 2019) and J1713+0747 (Shannon et al 2014;Liu et al 2016) at 1.4 GHz, but high for PSR B1855+09 (Lam et al 2019) at 1.4 GHz compared to previous studies. But the fact that PSR J1022+1001 has lower values of jitter recorded in other studies (Liu et al 2015;Feng et al 2020;Parthasarathy et al 2021) could indicate variable jitter noise. The contribution to the pulsar noise budget from jitter for PSR J1022+1001 and PSR J1713+0747 is higher at 4.5 GHz than at 1.38 GHz.…”

“…Following Liu et al (2015) and Feng et al (2020), we measured the rms timing residuals of single pulses from the leading and trailing component separately. Considering all single pulses with S/N> 5 results in rms timing residuals of ≈ 74 𝜇s and ≈ 48 𝜇s for leading and trailing components respectively.…”

“…Single-pulse studies of MSPs have been sparse due to signal-tonoise ratio limitations due to their low fluxes (Kramer et al 1998) and data acquisition requirements such as the need for high time resolution sampling. The few previous studies have revealed highly linearly polarized single pulses and sub-pulse microstructure in J0437−4715 (Jenet et al 1998;Osłowski et al 2014), giant pulses from B1937+21 (Jenet et al 2001), pulse jittering from PSR J1713+0747 (Shannon & Cordes 2012) and PSR J1022+1001 (Liu et al 2015;Feng et al 2020), and sub-pulse drifting from PSR J1713+0747 (Liu et al 2015).…”