Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-02-27
Astrophys.J.659:L77-L80,2007
Astronomy and Astrophysics
Astrophysics
4 pages, 3 figures, Accepted by ApJ letters
Scientific paper
10.1086/516750
We present the first results using the Reuven Ramaty High-Energy Solar Spectroscopic Imager, RHESSI, to observe solar X-ray emission not associated with active regions, sunspots or flares (the quiet Sun). Using a newly developed chopping technique (fan-beam modulation) during seven periods of offpointing between June 2005 to October 2006, we obtained upper limits over 3-200 keV for the quietest times when the GOES12 1-8A flux fell below $10^{-8}$ Wm$^{-2}$. These values are smaller than previous limits in the 17-120 keV range and extend them to both lower and higher energies. The limit in 3-6 keV is consistent with a coronal temperature $\leq 6$ MK. For quiet Sun periods when the GOES12 1-8A background flux was between $10^{-8}$ Wm$^{-2}$ and $10^{-7}$ Wm$^{-2}$, the RHESSI 3-6 keV flux correlates to this as a power-law, with an index of $1.08 \pm 0.13$. The power-law correlation for microflares has a steeper index of $1.29 \pm 0.06$. We also discuss the possibility of observing quiet Sun X-rays due to solar axions and use the RHESSI quiet Sun limits to estimate the axion-to-photon coupling constant for two different axion emission scenarios.
Bibber Karl van
Hannah Iain G.
Hudson Hugh S.
Hurford Gordon J.
Lin Robert P.
No associations
LandOfFree
First limits on the 3-200 keV X-ray spectrum of the quiet Sun using RHESSI does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with First limits on the 3-200 keV X-ray spectrum of the quiet Sun using RHESSI, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and First limits on the 3-200 keV X-ray spectrum of the quiet Sun using RHESSI will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-524180