Short time scale pulse stability of the Crab pulsar in the optical band

Карпов, С.; Beskin, G.; Biryukov, A. V.; Debur, V.; Plokhotnichenko, V. L.; Redfern, M.; Shearer, A.

doi:10.1007/s10509-007-9373-3

Cited by 11 publications

(8 citation statements)

References 10 publications

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“…Our results for the stability of the pulse profile (differences of up to ∼10 µs on a time scale of a day and even smaller variations on a time scale of less than a day; see Fig. 4) are not consistent with the results from Karpov et al (2007) who present variations of up to ∼150 µs in a fraction of a day. However, this variation is only present in a small part of their data set (December 2005 and January 2006), while the remainder of their data (obtained in December 1994and 1999, and November 2003 do not show substantial variations.…”

Section: Discussioncontrasting

confidence: 99%

“…We consider it unlikely that this night-to-night variation is solely caused by variations in the DM, since a variation of ∼1 times that of typical monthly variations is needed in 1 day. Variations in the peak position on time scales of days and shorter are studied in more detail by Karpov et al (2007), who find, during one observation, variations at the ∼150 μs-level.…”

Section: Optical-radio Lagmentioning

confidence: 99%

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Simultaneous absolute timing of the Crab pulsar at radio and optical wavelengths

Oosterbroek¹,

Cognard

Golden

et al. 2008

A&A

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Context. The Crab pulsar emits across a large part of the electromagnetic spectrum. Determining the time delay between the emission at different wavelengths will allow to better constrain the site and mechanism of the emission. We have simultaneously observed the Crab Pulsar in the optical with S-Cam, an instrument based on Superconducting Tunneling Junctions (STJs) with μs time resolution and at 2 GHz using the Nançay radio telescope with an instrument doing coherent dedispersion and able to record giant pulses data. Aims. We have studied the delay between the radio and optical pulse using simultaneously obtained data therefore reducing possible uncertainties present in previous observations. Methods. We determined the arrival times of the (mean) optical and radio pulse and compared them using the tempo2 software package.Results. We present the most accurate value for the optical-radio lag of 255±21 μs and suggest the likelihood of a spectral dependence to the excess optical emission asociated with giant radio pulses.

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Section: Discussioncontrasting

confidence: 99%

Section: Optical-radio Lagmentioning

confidence: 99%

Simultaneous absolute timing of the Crab pulsar at radio and optical wavelengths

Oosterbroek¹,

Cognard

Golden

et al. 2008

A&A

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“…the pulse shape agrees well with the 33-year-old pulse profile obtained by Groth (1975), as well as with the more recent one by Karpov et al (2007).…”

Section: Resultssupporting

confidence: 88%

Aqueye optical observations of the Crab Nebula pulsar

Germanà

Zampieri

Barbieri

et al. 2012

A&A

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Context. We observed the Crab pulsar in October 2008 at the Copernico Telescope in Asiago -Cima Ekar with the optical photon counter Aqueye (the Asiago Quantum Eye), which has the best temporal resolution and accuracy ever achieved in the optical domain (hundreds of picoseconds). Aims. Our goal was to perform a detailed analysis of the optical period and phase drift of the main peak of the Crab pulsar and compare it with the Jodrell Bank ephemerides. Methods. We determined the position of the main peak using the steepest zero of the cross-correlation function between the pulsar signal and an accurate optical template. Results. The pulsar rotational period and period derivative have been measured with great accuracy using observations covering only a two day time interval. The error on the period is 1.7 ps, limited only by the statistical uncertainty. Both the rotational frequency and its first derivative agree with those from the Jodrell Bank radio ephemerides archive. We also found evidence that the optical peak precedes the radio peak by ∼230 μs. The distribution of phase residuals of the whole dataset is slightly more scattered than that of a synthetic signal generated as a sequence of pulses distributed in time with the probability proportional to the pulse shape. Conclusions. The counting statistics and quality of the data allowed us to determine the pulsar period and period derivative with great accuracy in two days only. The time of arrival of the optical peak of the Crab pulsar precedes the radio peak in agreement with what was recently reported in the literature. The distribution of the phase residuals can be approximated with a Gaussian and is consistent with being completely caused by photon noise (for the best data sets).

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“…It is characterized by a double-peak folded profile, separated E-mail: luca.zampieri@oapd.inaf.it in phase by ∼ 0.4 (or ∼ 140 0 ). It is very stable (Zampieri et al 2011), although marginal evidence for a secular decrease in luminosity (Nasuti et al 1996) and weak variations in the pulse shape (Karpov et al 2007) have been reported.…”

Section: Introductionmentioning

confidence: 98%

Optical phase coherent timing of the Crab nebula pulsar with Iqueye at the ESO New Technology Telescope

Zampieri

Čadež

Barbieri

et al. 2014

Monthly Notices of the Royal Astronomical Society

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The Crab nebula pulsar was observed in 2009 January and December with a novel very fast optical photon counter, Iqueye, mounted at the ESO 3.5 m New Technology Telescope. Thanks to the exquisite quality of the Iqueye data, we computed accurate phase coherent timing solutions for the two observing runs and over the entire year 2009. Our statistical uncertainty on the determination of the phase of the main pulse and the rotational period of the pulsar for short (a few days) time intervals are ≈ 1 µs and ∼0.5 ps, respectively. Comparison with the Jodrell Bank radio ephemerides shows that the optical pulse leads the radio one by ∼ 240 µs in January and ∼ 160 µs in December, in agreement with a number of other measurements performed after 1996. A third-order polynomial fit adequately describes the spin-down for the 2009 January plus December optical observations. The phase noise is consistent with being Gaussian distributed with a dispersion σ of ≈ 15 µs in most observations, in agreement with theoretical expectations for photon noise-induced phase variability.

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Short time scale pulse stability of the Crab pulsar in the optical band

Cited by 11 publications

References 10 publications

Simultaneous absolute timing of the Crab pulsar at radio and optical wavelengths

Simultaneous absolute timing of the Crab pulsar at radio and optical wavelengths

Aqueye optical observations of the Crab Nebula pulsar

Optical phase coherent timing of the Crab nebula pulsar with Iqueye at the ESO New Technology Telescope

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