Coherently Dedispersed Polarimetry of Millisecond Pulsars

Stairs, I. H.; Thorsett, S. E.; Camilo, F.

doi:10.1086/313245

Cited by 104 publications

(251 citation statements)

References 29 publications

Supporting

Mentioning

196

Contrasting

Order By: Relevance

“…), based on the template polarisation profile from European Pulsar Network Pulse Profile Database (Stairs et al 1999) showing consistent polarimetry with previous published results. For this calibration scheme, we used both the single-axis and the reception description of the receiver properties, the latter of which models both the differential gain and cross-coupling of the two feeds (Ord et calibrated data were then processed by following the same procedure as described above.…”

Section: Variation Of Integrated Profiles and Sub-pulse Occurrencesupporting

confidence: 89%

Single-pulse and profile-variability study of PSR J1022+1001

Karuppusamy

Lee

et al. 2015

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Millisecond pulsars (MSPs) are known as highly stable celestial clocks. Nevertheless, recent studies have revealed the unstable nature of their integrated pulse profiles, which may limit the achievable pulsar timing precision. In this paper, we present a case study on the pulse profile variability of PSR J1022+1001. We have detected approximately 14,000 sub-pulses (components of single pulses) in 35-hr long observations, mostly located at the trailing component of the integrated profile. Their flux densities and fractional polarisation suggest that they represent the bright end of the energy distribution in ordinary emission mode and are not giant pulses. The occurrence of sub-pulses from the leading and trailing components of the integrated profile is shown to be correlated. For sub-pulses from the latter, a preferred pulse width of approximately 0.25 ms has been found. Using simultaneous observations from the Effelsberg 100-m telescope and the Westerbork Synthesis Radio Telescope, we have found that the integrated profile varies on a timescale of a few tens of minutes. We show that improper polarisation calibration and diffractive scintillation cannot be the sole reason for the observed instability. In addition, we demonstrate that timing residuals generated from averages of the detected sub-pulses are dominated by phase jitter, and place an upper limit of ∼ 700 ns for jitter noise based on continuous 1-min integrations.

show abstract

Section: Variation Of Integrated Profiles and Sub-pulse Occurrencesupporting

confidence: 89%

Single-pulse and profile-variability study of PSR J1022+1001

Karuppusamy

Lee

et al. 2015

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Our analysis shows that the linear polarisation fraction increases monotonically with decreasing observing frequency for all components. As was noted in Xilouris et al (1998) and Stairs et al (1999), the 1400 MHz and 600 MHz profiles are moderately circularly polarised, having fractions of ≈17% and ≈10%, respectively. At 150 MHz, the circular polarisation fraction remains low, at ≈9%.…”

Section: Psr J1012+5307supporting

confidence: 66%

“…The polarisation of this pulsar has been studied at 600 MHz and 1400 MHz Stairs et al 1999). The corresponding profiles are shown in Fig.…”

Section: Psr J1012+5307mentioning

confidence: 99%

Pulsar polarisation below 200 MHz: Average profiles and propagation effects

Noutsos

Sobey

Kondratiev

et al. 2015

A&A

110

View full text Add to dashboard Cite

Aims. We present the highest-quality polarisation profiles to date of 16 non-recycled pulsars and four millisecond pulsars, observed below 200 MHz with the LOFAR high-band antennas. Based on the observed profiles, we perform an initial investigation of expected observational effects resulting from the propagation of polarised emission in the pulsar magnetosphere and the interstellar medium. Methods. The polarisation data presented in this paper have been calibrated for the geometric-projection and beam-shape effects that distort the polarised information as detected with the LOFAR antennas. We have used RM Synthesis to determine the amount of Faraday rotation in the data at the time of the observations. The ionospheric contribution to the measured Faraday rotation was estimated using a model of the ionosphere. To study the propagation effects, we have compared our low-frequency polarisation observations with archival data at 240, 400, 600, and 1400 MHz. Results. The predictions of magnetospheric birefringence in pulsars have been tested using spectra of the pulse width and fractional polarisation from multifrequency data. The derived spectra offer only partial support for the expected effects of birefringence on the polarisation properties, with only about half of our sample being consistent with the model's predictions. It is noted that for some pulsars these measurements are contaminated by the effects of interstellar scattering. For a number of pulsars in our sample, we have observed significant variations in the amount of Faraday rotation as a function of pulse phase, which is possibly an artefact of scattering. These variations are typically two orders of magnitude smaller than that observed at 1400 MHz by Noutsos et al. (2009), for a different sample of southern pulsars. In this paper we present a possible explanation for the difference in magnitude of this effect between the two frequencies, based on scattering. Finally, we have estimated the magnetospheric emission heights of low-frequency radiation from four pulsars, based on the phase lags between the flux-density and the PA profiles, and the theoretical framework of Blaskiewicz et al. (1991, ApJ, 370, 643). These estimates yielded heights of a few hundred km; at least for PSR B1133+16, this is consistent with emission heights derived based on radius-to-frequency mapping, but is up to a few times larger than the recent upper limit based on pulsar timing. Conclusions. Our work has shown that models, like magnetospheric birefringence, cannot be the sole explanation for the complex polarisation behaviour of pulsars. On the other hand, we have reinforced the claim that interstellar scattering can introduce a rotation of the PA with frequency that is indistinguishable from Faraday rotation and also varies as a function of pulse phase. In one case, the derived emission heights appear to be consistent with the predictions of radius-to-frequency mapping at 150 MHz, although this interpretation is subject to a number of systematic uncertainties.

show abstract

“…Stairs et al (1999) subsequently determined the magnetic inclination angle to be consistent with 0 • , based on a fit of the rotating vector model (RVM, see Radhakrishnan & Cooke 1969) to observations at 410 and 610 MHz, thereby confirming the classification as an aligned rotator. We detected PSR J0218+4232 in the VLSSr data with a flux density of 2.9±0.4 Jy.…”

Section: Psr J0218+4232mentioning

confidence: 74%

Low-frequency spectral turn-overs in millisecond pulsars studied from imaging observations

Kuniyoshi

Verbiest

Lee

et al. 2015

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

Measurements of pulsar flux densities are of great importance for understanding the pulsar emission mechanism and for predictions of pulsar survey yields and the pulsar population at large. Typically these flux densities are determined from phase-averaged "pulse profiles", but this method has limited applicability at low frequencies because the observed pulses can easily be spread out by interstellar effects like scattering or dispersion, leading to a non-pulsed continuum component that is necessarily ignored in this type of analysis. In particular for the class of the millisecond pulsars (MSPs) at frequencies below 200 MHz, such interstellar effects can seriously compromise detectability and measured flux densities. In this paper we investigate MSP spectra based on a complementary approach, namely through investigation of archival continuum imaging data. Even though these images lose sensitivity to pulsars since the on-pulse emission is averaged with off-pulse noise, they are insensitive to effects from scattering and provide a reliable way to determine the flux density and spectral indices of MSPs based on both pulsed and unpulsed components. Using the 74 MHz VLSSr as well as the 325 MHz WENSS and 1.4 GHz NVSS catalogues, we investigate the imaging flux densities of MSPs and evaluate the likelihood of spectral turn-overs in this population. We determine three new MSP spectral indices and identify six new MSPs with likely spectral turn-overs.

show abstract

Coherently Dedispersed Polarimetry of Millisecond Pulsars

Cited by 104 publications

References 29 publications

Single-pulse and profile-variability study of PSR J1022+1001

Single-pulse and profile-variability study of PSR J1022+1001

Pulsar polarisation below 200 MHz: Average profiles and propagation effects

Low-frequency spectral turn-overs in millisecond pulsars studied from imaging observations

Contact Info

Product

Resources

About