Timing of young radio pulsars – I. Timing noise, periodic modulation, and proper motion

Parthasarathy, A.; Shannon, R. M.; Johnston, S.; Lentati, L.; Bailes, M.; Dai, Shi; Kerr, M.; Manchester, R. N.; Osłowski, S.; Sobey, C.; Straten, W. van; Weltevrede, P.

doi:10.1093/mnras/stz2383

Cited by 97 publications

(105 citation statements)

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“…Even when removing the deterministic spin-down model, there is a strong red-noise process remaining in the residuals. From the best-fitting model with 4 discrete state switches we estimate α = 3.5(3) and log 10 (A red ) = −5.7(3) which implies spin variations 3 orders of magnitude larger than the long-term red noise processes seen in normal pulsars (Parthasarathy et al 2019), or alternatively that Swift J1818.0−1607 experiences a similar amount of timing noise over our 2-month dataset that a typical pulsar might experience in 10 years. For comparison with other studies, we also report these parameters for a model without any ν and ν changes as α = 5.0(2) and log 10 (A red ) = −4.0(2), although this model is disfavoured in our analysis.…”

Section: Timing and Spin Evolutionmentioning

confidence: 87%

High-cadence observations and variable spin behaviour of magnetar Swift J1818.0−1607 after its outburst

Champion

Cognard

Cruces

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We report on multi-frequency radio observations of the new magnetar Swift J1818.0−1607, following it for more than one month with high cadence. The observations commenced less than 35 hours after its registered first outburst. We obtained timing, polarisation and spectral information. Swift J1818.0−1607 has an unusually steep spectrum for a radio emitting magnetar and also has a relatively narrow and simple pulse profile. The position angle swing of the polarisation is flat over the pulse profile, possibly suggesting that our line-of-sight grazes the edge of the emission beam. This may also explain the steep spectrum. The spin evolution shows large variation in the spin-down rate, associated with four distinct timing events over the course of our observations. Those events may be related to the appearance and disappearance of a second pulse component. The first timing event coincides with our actual observations, while we did not detect significant changes in the emission properties which could reveal further magnetospheric changes. Characteristic ages inferred from the timing measurements over the course of months vary by nearly an order of magnitude. A longer-term spin-down measurement over approximately 100 days suggests an characteristic age of about 500 years, larger than previously reported. Though Swift J1818.0−1607 could still be one of the youngest neutron stars (and magnetars) detected so far, we caution using the characteristic age as a true-age indicator given the caveats behind its calculation.

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Section: Timing and Spin Evolutionmentioning

confidence: 87%

High-cadence observations and variable spin behaviour of magnetar Swift J1818.0−1607 after its outburst

Champion

Cognard

Cruces

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…The method we use for assessing timing noise strength was developed in parallel with Parthasarathy et al (2019), in which timing noise strength is inferred from the red noise amplitude and spectral index, obtained via parameter estimation with T N , and the observation span as…”

Section: Quantifying Timing Noise Strengthmentioning

confidence: 99%

The UTMOST pulsar timing programme – II. Timing noise across the pulsar population

Lower

Bailes

Shannon

et al. 2020

Monthly Notices of the Royal Astronomical Society

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While pulsars possess exceptional rotational stability, large scale timing studies have revealed at least two distinct types of irregularities in their rotation: red timing noise and glitches. Using modern Bayesian techniques, we investigated the timing noise properties of 300 bright southern-sky radio pulsars that have been observed over 1.0-4.8 years by the upgraded Molonglo Observatory Synthesis Telescope (MOST). We reanalysed the spin and spin-down changes associated with nine previously reported pulsar glitches, report the discovery of three new glitches and four unusual glitch-like events in the rotational evolution of PSR J1825−0935. We develop a refined Bayesian framework for determining how red noise strength scales with pulsar spin frequency (ν) and spin-down frequency (ν), which we apply to a sample of 280 non-recycled pulsars. With this new method and a simple power-law scaling relation, we show that red noise strength scales across the non-recycled pulsar population as ν a |ν| b , where a = −0.84 +0.47 −0.49 and b = 0.97 +0.16 −0.19 . This method can be easily adapted to utilise more complex, astrophysically motivated red noise models. Lastly, we highlight our timing of the double neutron star PSR J0737−3039, and the rediscovery of a bright radio pulsar originally found during the first Molonglo pulsar surveys with an incorrectly catalogued position.

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“…We note that of the 4 radio-only pulsars, 3 of them have poor radio timing which means an optimum deep γ-ray search cannot be performed. There is also evidence that rotation irregularities in pulsars scale with the spin parameters and hence closely follow E. Timing noise, which causes phase wander of the timing residuals, can be severe in the high E pulsars (Shannon & Cordes 2010;Parthasarathy et al 2019) which reduces the sensitivity in blind γ-ray searches. Furthermore, the occurrence of abrupt changes in spin period caused by glitches increases for higher values of P/P 2 (Fuentes et al 2017).…”

Section: Where Are the High E γ-Ray Pulsars?mentioning

confidence: 99%

The Galactic population and properties of young, highly energetic pulsars

Johnston

Smith

Karastergiou

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The population of young, non-recycled pulsars with spin down energies $\dot{E} >10^{35}$ erg s−1 is sampled predominantly at γ-ray and radio wavelengths. A total of 137 such pulsars are known, with partial overlap between the sources detectable in radio and γ-rays. We use a very small set of assumptions in an attempt to test whether the observed pulsar sample can be explained by a single underlying population of neutron stars. For radio emission we assume a canonical conal beam with a fixed emission height of 300 km across all spin periods and a luminosity law which depends on $\dot{E}^{0.25}$. For γ-ray emission we assume the outer-gap model and a luminosity law which depends on $\dot{E}^{0.5}$. We synthesise a population of fast-spinning pulsars with a birth rate of one per 100 years. We find that this simple model can reproduce most characteristics of the observed population with two caveats. The first is a deficit of γ-ray pulsars at the highest $\dot{E}$ which we surmise to be an observational selection effect due to the difficulties of finding γ-ray pulsars in the presence of glitches without prior knowledge from radio frequencies. The second is a deficit of radio pulsars with interpulse emission, which may be related to radio emission physics. We discuss the implications of these findings.

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Timing of young radio pulsars – I. Timing noise, periodic modulation, and proper motion

Cited by 97 publications

References 66 publications

High-cadence observations and variable spin behaviour of magnetar Swift J1818.0−1607 after its outburst

High-cadence observations and variable spin behaviour of magnetar Swift J1818.0−1607 after its outburst

The UTMOST pulsar timing programme – II. Timing noise across the pulsar population

The Galactic population and properties of young, highly energetic pulsars

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