On the Narrowing of Radio Recombination Lines at High Principal Quantum Numbers

Griem, H.R.

doi:10.1086/428771

Cited by 16 publications

(27 citation statements)

References 7 publications

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“…However, when the ion density is very low, ions can no longer be considered static during the typical dipole relaxation time. As already pointed out by Griem (2005) -see also Griem (1967Griem ( , 1974 -, this happens, for example, for the conditions of radio recombination lines studied in Bell et al (2000), where ions effect can be considered as "impact". In those cases, then, the dominant broadening is ionic impact, as their fields, as they are slower, have a correlation integral (42) larger than that of electrons 3 .…”

Section: Resultsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

“…In this framework a controversy (see Griem 2005 and works cited therein) in explaining these disagreements without changing the usual frame of Stark broadening theories occur. To our knowledge, these discrepancies remain and have even been qualified as "mysterious" (Griem 2005;Watson 2006) 1 . In this context, approximate expressions are required to calculate transition probabilities between states with very high principal quantum numbers (n > 100) (Watson 2006;Hey 2006).…”

Section: Introductionmentioning

confidence: 99%

“…1 About this "mystery" see the comment in the conclusions of Griem (2005) that appears as a private communication with M. Bell.…”

Section: Introductionmentioning

confidence: 99%

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Exact expression of the impact broadening operator for hydrogen Stark broadening

Ma¹,

González

Talin³

et al. 2007

A&A

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Aims. Recent measurements on the Stark broadening of radio recombination lines show values and trends in disagreement with conventional theories. Different attemps to explain those disagreements have not been successfull for any of the employed theoretical models. In particular, the impact model that describes well the physical conditions at which the studied broadenings occur, shows a functional trend upon the principal quantum number of the studied transitions that does not correspond to the experimental observations. Methods. High values of the principal quantum number require computable formulas for the calculation of transition probabilities. Some of those expressions have been published, leading to approximate formulas on the dependence of the line width versus the principal quantum number of the upper level of the transition. Results. In this work an exact expression for the hydrogen Stark width in the frame of impact approximation is given.

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Section: Resultsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…1 About this "mystery" see the comment in the conclusions of Griem (2005) that appears as a private communication with M. Bell.…”

Section: Introductionmentioning

confidence: 99%

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Exact expression of the impact broadening operator for hydrogen Stark broadening

Ma¹,

González

Talin³

et al. 2007

A&A

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“…Using the frequency switching observing technique we have found evidence that the impact broadened linewidths of hydrogen recombination lines near 6 GHz appear to become much narrower than predicted at high quantum numbers, n > 200 (Bell 1997;Bell et al 2000;Bell et al 2011;Bell 2011). Although a possible explanation for this was suggested by Oks (2004), this was refuted by Griem (2005). It was later demonstrated by Bell (2011) that when observations at other radio frequencies were taken into account the line narrowing appeared to be correlated with the density of recombination lines in frequency space.…”

Section: Introductionmentioning

confidence: 92%

More on the narrowing of impact broadened radio recombination lines at high principal quantum number

Bell

2012

Astrophys Space Sci

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Recently Alexander and Gulyaev have suggested that the apparent decrease in impact broadening of radio recombination lines seen at high principal quantum number n may be a product of the data reduction process, possibly resulting from the presence of noise on the telescope spectra that is not present on the calculated comparison spectra. This is an interesting proposal. However, there are serious problems with their analysis that need to be pointed out. Perhaps the most important of these is the fact that for principal quantum numbers below n = 200, where the widths are not in question, their processed generated profile widths do not fit the widths of the processed lines obtained at the telescope. After processing, the halfwidths of the generated and telescope profiles must agree below n = 200 if we are to believe that the processed generated linewidths above n = 200 are meaningful. Theirs do not. Furthermore, we find that after applying the linewidth reduction factors found by Alexander and Gulyaev for their noise added profiles to our generated profiles to simulate their noise adding effect, the processed widths we obtain still do not come close to explaining the narrowing seen in the telescope lines for n values in the range 200 < n < 250. It is concluded that what is needed to solve this mystery is a completely new approach using a different observing technique instead of simply a further manipulation of the frequency-switched data.

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