Low-frequency radio spectra of crab nebula, Virgo A, and Cygnus A

Tokarev, Yu. V.

doi:10.1007/bf02120983

Cited by 5 publications

(5 citation statements)

References 10 publications

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“…Since the high frequency radio flux of the Crab pulsar is F ν = 646(ν/400 MHz) −3.1 mJy for ν > 400 MHz [33,36], there seems a spectral break around 100 MHz. The low frequency spectrum extends down to at least 5.6 MHz with a spectral index α = −2.09 [37,38]. Fitted line in this range is F ν ∼ 50(ν/100 MHz) −2 Jy for ν < 100 MHz.…”

Section: Setupmentioning

confidence: 99%

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Constraint on Pulsar Wind Properties from Induced Compton Scattering off Radio Pulses

Tanaka¹,

Takahara²

2013

Preprint

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Pulsar winds have longstanding problems in energy conversion and pair cascade processes which determine the magnetization σ, the pair multiplicity κ and the bulk Lorentz factor γ of the wind. We study induced Compton scattering by a relativistically moving cold plasma to constrain wind properties by imposing that radio pulses from the pulsar itself are not scattered by the wind as was first studied by Wilson & Rees. We find that relativistic effects cause a significant increase or decrease of the scattering coefficient depending on scattering geometry. Applying to the Crab, we consider uncertainties of an inclination angle of the wind velocity with respect to the radio beam θ pl and the emission region size r e which determines an opening angle of the radio beam. We obtain the lower limit γ 10 1.7 r 1/2 e,3 θ −1 pl (1 + σ) −1/4 (r e = 10 3 r e,3 cm) at the light cylinder r LC for an inclined wind θ pl > 10 −2.7 . For an aligned wind θ pl < 10 −2.7 , we require γ > 10 2.7 at r LC and an additional constraint γ > 10 3.4 r 1/5 e,3 (1 + σ) −1/10 at the characteristic scattering radius r c = 10 9.6 r 2/5 e,3 cm within which the 'lack of time' effect prevents scattering. Considering the lower limit κ 10 6.6 suggested by recent studies of the Crab Nebula, for r e = 10 3 cm, we obtain the most optimistic constraint 10 1.7 γ 10 3.9 and 10 6.6 κ 10 8.8 which are independent of r when θ pl ∼ 1 and 1 + σ ∼ 1 at r LC .

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Section: Setupmentioning

confidence: 99%

“…Fitted line in this range is F ν ∼ 50(ν/100 MHz) −2 Jy for ν < 100 MHz. Observational data are taken from [33,37,38]. characterizing the r-dependence of the velocity u(r) as γ ∝ r a and θ pl ∝ r −b .…”

Section: Setupmentioning

confidence: 99%

Constraint on Pulsar Wind Properties from Induced Compton Scattering off Radio Pulses

Tanaka¹,

Takahara²

2013

Preprint

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“…When experimentally obtaining the spectral dependence S(ν) in a broad frequency range, the values τ 0 and D are determined on the basis of Eqs. (22), (25), or (24). In this case, the value B and, hence, the electron temperature T e are found from Eqs.…”

Section: Absorption Of Radiation In the Plasma Located In A Non-thermmentioning

confidence: 99%

“…Unique measurements of the spectral flux density of radio emission from this source at the lowest frequencies (5.6 and 8.9 MHz) are presented in[24,25].…”

mentioning

confidence: 99%

Experimental determination of physical processes in space, leading to deviations of radio synchrotron radiation spectra from the power law

Men

2008

Radiophys Quantum El

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UDC 524.7.77We present universal formulas for spectral characteristics of cosmic radio sources of synchrotron radiation upon the presence of spectral density maxima at certain frequencies (spectra with negative curvature) taking into account most typical physical processes observed in space. On the basis of long-term observations of angular radiation structure of cosmic radio sources in the decameter wavelength range by the URAN radio interferometer system, we determine most probable physical processes resulting in spectra with extremum values for several quasars, radio galaxies, and their separate components. On the basis of these data, we estimate some parameters of cosmic medium, magnetic field, and angular sizes of compact radio sources and their components.

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“…This antenna has been the basis for creating VDR-300, a decameter radio telescope with an effective reception area of about 50000 m 2 , which is the largest among such devices in the northern hemisphere operated at frequencies below 10 MHz. Using this telescope in the periods of the minima of two last solar-activity cycles, first radio-isophote maps of the Galaxy for declinations δ ≥ 16 • were made up [122], spectra of the most powerful (calibrated) discrete radio sources of the northern sky sphere Cassiopea-A, Cygnus-A, Virgo-A, and the Crab nebula [137] at frequencies 5.6 and 8.9 MHz were measured, and the inhomogeneous structure of the transition region between the solar wind and the Jovian magnetosphere was studied by the method of observation of scintillations of decameter radio-emission L bursts in the 9-MHz range [138].…”

Section: Radioastronomical Observationsmentioning

confidence: 99%