Long-term flux density variations of pulsars:
 Theoretical structure functions and comparisons with observations

Zhou, Anyu; Wu, Xiaoguang; Esamdin, Ali

doi:10.1051/0004-6361:20030413

Cited by 6 publications

(2 citation statements)

References 30 publications

(44 reference statements)

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“…For exam-ple, Gupta et al (1993) present daily phase averaged flux densities of nine pulsars over a duration of 400 days. For the majority of pulsars in their sample the flux density changes were consistent with those predicted by refractive interstellar scintillation (also see Kaspi & Stinebring 1992;Stinebring et al 2000 andZhou et al 2003).…”

Section: Introductionsupporting

confidence: 66%

Time-domain and spectral properties of pulsars at 154 MHz

Bell

Murphy

Johnston

et al. 2016

Mon. Not. R. Astron. Soc.

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We present 154 MHz Murchison Widefield Array imaging observations and variability information for a sample of pulsars. Over the declination range −80• < δ < 10• we detect 17 known pulsars with mean flux density greater than 0.3 Jy. We explore the variability properties of this sample on timescales of minutes to years. For three of these pulsars, PSR J0953+0755, PSR J0437−4715 and PSR J0630−2834 we observe interstellar scintillation and variability on timescales of greater than 2 minutes. One further pulsar, PSR J0034−0721, showed significant variability, the physical origins of which are difficult to determine. The dynamic spectra for PSR J0953+0755 and PSR J0437−4715 show discrete time and frequency structure consistent with diffractive interstellar scintillation and we present the scintillation bandwidth and timescales from these observations. The remaining pulsars within our sample were statistically non-variable. We also explore the spectral properties of this sample and find spectral curvature in pulsars PSR J0835−4510, PSR J1752−2806 and PSR J0437−4715.

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Section: Introductionsupporting

confidence: 66%

Time-domain and spectral properties of pulsars at 154 MHz

Bell

Murphy

Johnston

et al. 2016

Mon. Not. R. Astron. Soc.

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“…We will call these pulsars type II pulsars. In our previous work (Zhou et al 2003a(Zhou et al , 2003b(Zhou et al , 2003c, we fitted the structure function of the flux density for some type I pulsars. We also present a twocomponent model (Zhou et al 2005) for the interstellar scattering by a super-Kolmogorov spectrum in the direction to the Vela pulsar, for which the observed logarithmic slope of the structure function is only 0.9.…”

Section: Introductionmentioning

confidence: 99%

Two-component scattering model and the electron density spectrum

Zhou

Tan

Esamdin

et al. 2009

Astrophys Space Sci

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In this paper, we discuss a rigorous treatment of the refractive scintillation caused by a two-component interstellar scattering medium and a Kolmogorov form of density spectrum. It is assumed that the interstellar scattering medium is composed of a thin-screen interstellar medium (ISM) and an extended interstellar medium. We consider the case that the scattering of the thin screen concentrates in a thin layer represented by a δ function distribution and that the scattering density of the extended irregular medium satisfies the Gaussian distribution. We investigate and develop equations for the flux density structure function corresponding to this two-component ISM geometry in the scattering density distribution and compare our result with the observations. We conclude that the refractive scintillation caused by this two-component ISM scattering gives a more satisfactory explanation for the observed flux density variation than does the single extended medium model. The level of refractive scintillation is strongly sensitive to the distribution of scattering material along the line of sight (LOS). The theoretical modulation indices are comparatively less sensitive to the scattering strength of the thin-screen medium, but they critically depend on the distance from the observer to the thin screen. The logarithmic slope of the structure function is sensitive to the scattering strength of the thin-screen medium, but is relatively insensitive to the thin-screen location. Therefore, the proposed model can be applied to interpret the structure functions of flux density observed in pulsar PSR B2111 + 46 and PSR B0136 + 57. The result suggests that the medium consists of a discontinuous distribution of plasma turbulence embedded in the interstellar medium. Thus our work provides some insight into the distribution of the scattering along the LOS to the pulsar PSR B2111 + 46 and PSR B0136 + 57.

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A study of the long-term flux density variation of PSRs B0329+54 and B1508+55

Esamdin

Zhou

2004

A&A

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Abstract.We have observed the flux densities of PSRs B0329+54 and B1508+55 for 460 days at 327 MHz using the 25 m telescope of NAOC Urumqi Observatory. The flux density time series and the corresponding structure functions are presented. Our observational results at 327 MHz and other observations at 74 MHz and 610 MHz are compared with the predictions of the refractive scintillation theory. The frequency dependence of the refractive scintillation parameters for PSR B0329+54 has been investigated. The results show that the long-term flux density modulations of PSR B0329+54 at the three frequencies are best described by a Kolmogorov spectrum for electron density inhomogeneities. For PSR B1508+55, we suggest that the spectrum of the electron density fluctuation has a power exponent β < 4.

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Long-term flux density variations of pulsars: Theoretical structure functions and comparisons with observations

Cited by 6 publications

References 30 publications

Time-domain and spectral properties of pulsars at 154 MHz

Time-domain and spectral properties of pulsars at 154 MHz

Two-component scattering model and the electron density spectrum

A study of the long-term flux density variation of PSRs B0329+54 and B1508+55

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