Re: images

[Jacco Vink <j.vink@sron.nl>]

Hi Tracey,

I agree. I named all images after the most dominant radiation process in
the energy band.  I did not mean to suggest that the continuum image
shows only continuum dominated filaments. Also note that these are just
narrow (or not so narrow) band images. These are not equivalent width
images, so some level of continuum is present in all images.

The 3-color images give in that sense somewhat more information
(but note that here scaling of individual bands also play a role).
E.g. the 3-color image in the center has Fe-K as blue, but also Fe-L
emission as red, so most Fe shows up as purple. The blueish region in
the West is therefore probably mostly due to continuum dominated
filaments. The RGB image on the right shows the continuum dominated
filaments as blueish.


Jacco

On Tue, 2004-05-11 at 16:53, Tracey DeLaney wrote:
> Hi Jacco,
> 
> I think what Larry's getting at is that your 4-6 keV image is not
> "continuum-dominated".  Yes, the emission shown is from a line free part
> of the spectrum, but the spectrum of everything shown in the 4-6 keV image
> is not continuum-dominated.  For instance, the big bright Si filament in
> the southeast shows up prominently in the 4-6 keV image, but the spectrum
> of that filament is NOT continuum-dominated.  The 4-6 keV image shows a
> combination of those features that are continuum-dominated and those
> features that are just very bright so that the 4-6 keV part of their
> spectrum is as bright as or brighter than the 4-6 keV part of the spectrum
> of truly continuum-dominated things.  The issue here is just one of
> wording.  What you are showing is 4-6 keV continuum emission NOT
> continuum-dominated emission.
> 
> I have the same worry, but to a much lesser extent for the 8-10 keV
> image.  From what I understand, the thermal emission drops off rapidly at
> high energies so that the level of thermal emission is small at 8-10 keV,
> however, I can still see areas of strong thermal emission in that
> image.  I wonder if the term continuum-dominated is appropriate for 8-10
> keV.
> 
> I'm also concerned about the FeK image to a small degree.  I realize that
> this is just standard labelling, but before interpreting everything in
> that image as due to Fe emission, the spectra of features must be
> interpreted.  For instance, in our continuum-dominated filaments to the
> west, we see that the high energy end of the spectrum is enhanced such
> that either the FeK line is hidden or that there is no significant
> FeK.  The result is that in a 6-7 keV image we see everything that is
> bright between 6 and 7 keV regardless of whether the brightness is due to
> the FeK line or due to very bright continuum.  Just remember that not
> everything in that image is Fe.  Of course, this same argument can be
> applied to every map you have which is why I'm not that concerned.
> 
> Tracey
> 
> 
> Jacco replied:
> > Yes continuum is 4 - 6 keV (although there may be some contamination
> > e.g. Ca He-b  @ 4.48 keV). I enclose here an other image that is a
> > superposition of more carefully selected bands between 2.2 and 6.3 keV.
> 
> 
> Larry asked:
> >> Jacco - great images.  what do you mean by "continuum dominated"?
> >> straight channel maps from somewhere in the 4-6 keV region?  lr
-- 
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 Dr Jacco Vink                        || e-mail   : J.Vink@sron.nl
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