[Yt-dev] Simulated Observations: Request for Corrections

[j s oishi]

While we're on radio maps, I think we could also very easily add Mark
Krumholz's ALMA tools for generating molecular emission maps from cold
molecular gas for present-day star formation. I'd be happy to lead
that effort once I dig out from the backlog of work piled up while I
have been preparing for upcoming talks...

On Tue, Mar 1, 2011 at 7:38 AM, John Wise <jwise at astro.princeton.edu> wrote:
> Hi Matt,
>
> This is great that you sketched out the plan to make simulated observations through yt.  I think another addition would be 21cm maps.  I implemented these in enzo's projection tool (version 2), but I can add these to yt soon.
>
> Also, we can probably put some pre-defined PSFs for various telescopes / detectors when the user wants to make an image.  Conversions from physical scales to angles would be handy as well, i.e. making a 1 arcmin^2 image.
>
> John
>
> On 1 Mar 2011, at 10:08, Eric Hallman wrote:
>
>> Matt,
>>  if we're being generous, we can include the capability to make SZ Compton y maps.  Also Kinematic SZ.  I think those are fields in yt now are they not (SZY and SZ_Kinetic)? Or are those user-derived fields not in public yt?
>>
>> cheers,
>>
>> On Mar 1, 2011, at 10:02 AM, Matthew Turk wrote:
>>
>>> Hi all,
>>>
>>> I've been taking stock of where we are for simulated observations, and
>>> I wanted to run this past everyone to make sure I'm not missing
>>> anything.  I think we have four mechanisms for generating something
>>> that could *generously* be called a "Simulated Observation," but for
>>> each approach there are caveats.  If someone has something to add, in
>>> terms of capability or caveats, I would be eager to hear.  I have not
>>> included any methods for generating spectra from galaxies, but I
>>> believe this may have been done using the second method below.
>>>
>>> = X-ray Observations =
>>>
>>> Under the assumption of optically thin gas, projections can be made
>>> using emissivity to generated simulated observations.  yt includes a
>>> method for handling output from CLOUDY in the ROCO (Smith et al 2008)
>>> format, and generating integrated emissivity over given energy ranges.
>>>
>>> Caveats: The ROCO format for input requires some non-trivial handling
>>> of CLOUDY output.
>>>
>>> = SED Generation and Deposition =
>>>
>>> Using BC03 models for stellar population synthesis, star particles in
>>> a given calculation can be assigned an integrated flux for a specific
>>> bandpass.  These fluxes can then be combined using either projections
>>> or volume rendering.  This can use CIC interpolation to deposit a
>>> total flux into each cell (which should be flux-conserving, modulo a
>>> multiplicative factor not currently included) which is then either
>>> projected or volume rendered.
>>>
>>> Caveats: The deposition method produces far too washed out and murky
>>> results.  The multiplicative factor is not currently set correctly
>>> universally.
>>>
>>> = Thermal Gas Emission =
>>>
>>> Applying a black body spectrum to the thermal content of the gas, we
>>> can volume render the domain and apply absorption based on broad
>>> arguments of scattering.  One could theoretically include star
>>> particles as point sources in this, using recent changes to the volume
>>> renderer.
>>>
>>> Caveats: Scattering that results in re-emission is completely
>>> neglected, such as Halpha emission.  Scattering that results in just
>>> attenuating the emission is set in an ad hoc fashion.  Emission from
>>> point sources, if included at all, is included in a non-conservative
>>> fashion.
>>>
>>> = Export to Sunrise =
>>>
>>> Data can be exported to Sunrise for simulated observation generation.
>>>
>>> Caveats: This process is poorly documented.
>>>
>>>
>>>
>>> Does that all sound about right?  Does anybody have any additions or
>>> corrections to this?
>>>
>>> Thanks,
>>>
>>> Matt
>>> _______________________________________________
>>> Yt-dev mailing list
>>> Yt-dev at lists.spacepope.org
>>> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>>
>> Eric Hallman
>> Google Voice: (774) 469-0278
>> hallman13 at gmail.com
>>
>>
>>
>>
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