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: http://www.mso.anu.edu.au/pfrancis/pink/tech.html
Дата изменения: Unknown Дата индексирования: Tue Oct 2 01:25:43 2012 Кодировка: Поисковые слова: п п п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п р п |
Why the difference? Several rival theories were put forward:
The puzzle is: what are these red power-law sources? They appear pink to the human eye (I combined out BVR imaging weighted such that a sun-like star would appear white). They show broad emission-lines such as MgII and CIII] with roughly normal equivalent widths, so these are not classical BL Lac objects (H-beta, on the other hand, has an equivalent width that anticorrelates nicely with redness). We've measured the near-IR polarisation for a few of them and they are quite strongly polarised out beyond a micron. Many are reasonable X-ray sources as detected by ROSAT (Seibert et al. 1998, MNRAS 301, 261).
The problem is: how do you get synchrotron emission with a slope of -2? This is close to the reddest slope you can get for any plausible electron energy distribution. We can fit it with a cut-off in the electron energy distribution, but this cut-off has to be at 1 micron +- 30% in well over half of the quasars. This would argue for some fundamental physical process locking the cut-off here: we cannot think of any (naievely the cut-off should go as the square of the magnetic field). Even then, the predicted spectrum shouldn't be a pure power-law, due to the Big Blue Bump component coming in as shorter wavelengths (we need something blue to photoionise the BLR). So: a puzzle! Suggestions welcome!
We have a couple of papers almost ready to submit about the data and our modelling of it: watch this space!