Robin
New Member
I couple the distributions and kinematics of cold gas in galaxies w/ Bulge/Disk decompositions.
Posts: 13
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Post by Robin on Jul 25, 2017 16:00:17 GMT 8
Of course, projected 1D flux intensity plots can be very useful for quickly distinguishing the contributions from the bulge and disk component (albeit hiding much of the information in a 2D representation). profitEllipsePlot( ) is a good tool for deprojecting the image pixels into 1D surface brightness profiles for double component models; however, it does not allow for plotting of a single component model. If ever you had a reason to plot the 1D surface brightness profile of a single component fit, you can quickly get away with this by adding a pseudo second component with essentially zero flux: add_pseudo_bulge = function(model) # Add a zero-point magnitude bulge { # <param: model [list]> - Single component modellist. # <return: pseudo [list]> - A (pseudo) modellist containing a second null component. pseudo = model # copy model list for (key in names(model$sersic)){pseudo$sersic[[key]][2] = model$sersic[[key]][1]} # duplicate a second component pseudo$sersic$mag[1] = ZERO_POINT # set magnitude of bulge (loc=1) to ZERO_POINT return(pseudo) }
This can then be fed into profitEllipsePlot( ) as follows: profitEllipsePlot(Data=Data,modellist=add_pseudo_bulge(modellist)) Which yields something like the following:  The legend in the plot is, of course, misleading, but this is simply a diagnostic plot as it is probably more useful to investigate the 2D representation of the model residual.
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Post by Hosein on Jul 25, 2017 16:39:29 GMT 8
Works well!
Thanks Robin.
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asgr
Junior Member

Posts: 56
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Post by asgr on Aug 1, 2017 12:33:18 GMT 8
For a different route of considering the 1D profile it is worth looking at profitGetEllipses. This pretty well mimics what IRAF ellipse does (I say that, but I only have a rough idea how IRAF ellipse extracts its ellipses, I started from scratch when writing this approach). In principle you can "easily" overlay your profile, but in practice it is a little bit fiddly since you need to be careful to scale the magnitude to surface brightness correctly (i.e. correcting for the effects of boxiness and ellipticity). I should probably describe this in more detail at some point, but the Example included in the manual gives you some idea how this works in practice.
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Post by stefania on Feb 14, 2018 13:53:24 GMT 8
Hi,
I am using profitGetEllipses to do the 1D fit and then the 1D results as inputs for the 2D fit. I am correcting the magnitude for the bulge/disk axial ratio and pixscale, but the pixscale correction that I applied is not correct since my 1D flux is usually overestimated compared to the 2D result. Which is the right correction to apply at the magnitude when moving from the 1D to the 2D?
Thank you!
Stefania
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asgr
Junior Member

Posts: 56
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Post by asgr on Feb 16, 2018 9:39:31 GMT 8
Hi Stefania,
One thing- you should be using the version in profound (profoundGetEllipses). The ProFit version was deprecated a while ago. Should probably be doing the same thing, but just to be safe.
Depending on how you are doing things, you might not need to apply a pixel scale correction at all. The reason you give the pixel scale to the ellipse function is to get things in true surface brightness and radius, and this is used for the fitting. So bar the axial ratio, your magnitude should be correct.
Cheers,
A
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