Theory of type II radio emission from the foreshock of an interplanetary shock

Knock, S. A.; Cairns, Iver H.; Robinson, P. A.; Kuncic, Zdenka

doi:10.1029/2001ja000053

Cited by 89 publications

(161 citation statements)

References 34 publications

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“…Taken together, these observations suggest that type II emission is generated in multiple foreshock regions upstream of IP shocks. Theoretical models of electron reflection from the surface of interplanetary shocks are consistent with this model, producing electron beams and plasma radiation at f p and 2f p , which agree reasonably well with the observed quantities (Knock et al 2001Cairns et al 2003). …”

Section: Introductionsupporting

confidence: 70%

Structure on Interplanetary Shock Fronts: Type II Radio Burst Source Regions

Pulupa

Bale

2008

ApJ

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We present in situ observations of the source regions of interplanetary ( IP) type II radio bursts, using data from the Wind spacecraft during the period 1996-2002. We show the results of this survey, as well as in-depth analysis of several individual events. Each event analyzed in detail is associated with an interplanetary coronal mass ejection (ICME ) and an IP shock driven by the ICME. Immediately prior to the arrival of each shock, electron beams along the interplanetary magnetic field (IMF ) and associated Langmuir waves are detected, implying magnetic connection to a quasi-perpendicular shock front acceleration site. These observations are analogous to those made in the terrestrial foreshock region, indicating that a similar foreshock region exists on IP shock fronts. The analogy suggests that the electron acceleration process is a fast Fermi process, and this suggestion is borne out by loss cone features in the electron distribution functions. The presence of a foreshock region requires nonplanar structure on the shock front. Using Wind burst mode data, the foreshock electrons are analyzed to estimate the dimensions of the curved region. We present the first measurement of the lateral, shock-parallel scale size of IP foreshock regions. The presence of these regions on IP shock fronts can explain the fine structure often seen in the spectra of type II bursts. Subject headingg s: interplanetary medium -solar-terrestrial relations -Sun: coronal mass ejections (CMEs) -Sun: radio radiation

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Section: Introductionsupporting

confidence: 70%

Structure on Interplanetary Shock Fronts: Type II Radio Burst Source Regions

Pulupa

Bale

2008

ApJ

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“…This is based on calibrating against our combined models for QTN and the galactic background for the Wind WAVES receivers. This combined model can now be used to compare observations in detail with theoretical predictions for type II bursts [Knock et al, 2001;Florens et al, 2007] and type III bursts.…”

Section: Discussionmentioning

confidence: 99%

“…Of particular interest are observations of radio events that follow solar flares and coronal mass ejections (CMEs). Type II solar radio bursts, for example, are associated with radio emission produced near the local plasma frequency (f p ) and its harmonic (2f p ) upstream of a traveling shock wave, itself often driven ahead of a CME [Wild et al, 1963;Cane et al, 1981Cane et al, , 1987Reiner et al, 1998;Bale et al, 1999;Knock et al, 2001].…”

Section: Introductionmentioning

confidence: 99%

Prediction of background levels for the Wind WAVES instrument and implications for the galactic background radiation

et al. 2010

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[1] We investigate and predict the observed background levels for the TNR, RAD1, and RAD2 receivers when connected to the X, Y, and Z antennas of the WAVES instrument on the spacecraft Wind. The receivers are connected to either a single antenna, in "SEP" mode, or a combination of antennas, in "SUM" mode. With the TNR receiver in SEP (X) mode, the predicted backgrounds agree to within 20% when modeled using a two component model for the quasi-thermal plasma noise (QTN). Calibrating the RAD1 in SEP (X) mode observations against TNR allows us to calculate the relative receiver gain G R1 = 1.43 ± 0.18. Using the RAD1 data in SUM (X+Z) mode, the ratio of antenna gains is found to be R = 6.5, in agreement with preflight measurements. Observed differences between the SEP (X) and SUM (X+Z) modes are explained for the first time, and the predicted levels of QTN and galactic background are found to agree to within 20%. RAD2 is also calibrated against RAD1 and TNR, yielding a total gain G R2 G y = 2.5 ± 0.3. Differences between the predicted and observed galactic background spectra are used to estimate the effective antenna lengths for the X and Y antennas, which are found to be between the physical monopole antenna length L and the Hansen (1981) prediction of ffiffiffiffiffiffiffiffiffiffiffi ð2=3Þ p L. The analyses are consistent with the Novaco and Brown (1978) galactic background model, which decreases much faster than that of Cane (1979). Our model background spectrum is useful for theory-data comparisons of type II and III bursts.

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“…Bale et al [1999] studied the source region of that type II radio burst, using electron data measured on board Wind; from these observations, they could infer some large-scale shock structure in the source region upstream of the shock. Knock et al [2001] applied and refined the stochastic growth theory (SGT) to that type II burst, to interpret the flux densities they deduced from the dynamic spectrum of data observed by Reiner [2000].…”

Section: Introductionmentioning

confidence: 99%

“…Because our 128-s frequency swept receiver can measure one frequency only at a given time (on a 2-s step), it may miss an event occurring at a specific frequency within the sweep, namely f p , while scanning other frequencies, the exact start time at which the s/c detects the Langmuir waves may be estimated to be between 42 and 42 + 128 = 170 s before 0035:55 UT. At that time (of first detection of Langmuir waves), Ulysses enters the upstream boundary of the electron foreshock, where the solar wind electrons accelerated by the shock drive Langmuir waves at the upstream plasma frequency f pu [e.g., Filbert and Kellogg, 1979;Lacombe et al, 1988]; some of their energy is subsequently mode converted to the type II radio emission observed [Knock et al, 2001, and references therein].…”

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confidence: 99%

Radio tracking of the interplanetary coronal mass ejection driven shock crossed by Ulysses on 10 May 2001

et al. 2007

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[1] We report on the detection of type II radio emission which was observed for more than a day prior to the arrival of an interplanetary shock at Ulysses. We use local spectral emission peaks, computerized from time-averaged intensity spectra of the type II burst, to track the associated emitting shock. In the spectrogram plotted as a function of time and inverse frequency, these peaks appear as elongated clusters of data points, organized in fundamental-harmonic bands and delineating drifting emission features. Least squares linear fittings to identified clusters give straight traces with different slopes. Most of these, when extrapolated to the Sun, are found to converge nearly at the same starting time, allowing determination of the average shock speed. Shortly before the shock crossing, intense Langmuir waves were detected at the electron plasma frequency upstream of the shock. This plasma wave enhancement together with the radio emission observed predominantly at the harmonic of the plasma frequency, all point to the occurrence of the type II radio source region in the upstream electron foreshock. We have accurately substracted the thermal noise background from the observed emission intensity to deduce the type II brightness temperatures at the fundamental and harmonic near the shock crossing. The measured brightness temperature of the type II harmonic emission is found to peak at a value of '3 Â 10 13 K just after the shock crossing; just before, the harmonic brightness temperature is '10 12 K and the fundamental brightness temperature '8 Â 10 11 K.

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Theory of type II radio emission from the foreshock of an interplanetary shock

Cited by 89 publications

References 34 publications

Structure on Interplanetary Shock Fronts: Type II Radio Burst Source Regions

Structure on Interplanetary Shock Fronts: Type II Radio Burst Source Regions

Prediction of background levels for the Wind WAVES instrument and implications for the galactic background radiation

Radio tracking of the interplanetary coronal mass ejection driven shock crossed by Ulysses on 10 May 2001

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