[Yt-dev] Simulated Observations: Request for Corrections

[Britton Smith]

P.S. - the light ray tool, is currently undocumented.  I will add the
documentation in the next day or so.

On Tue, Mar 1, 2011 at 12:08 PM, Britton Smith <brittonsmith at gmail.com>wrote:

> We also have the light cone generator for simulated observations out to
> cosmological distances.  This works particularly well with the SZ fields.
> There is also the light ray tool for synthetic QSO sight lines that span
> cosmological epochs.  These can be used for absorption/emission line
> statistics and stats on distances of absorbers/emitters to galaxies (halos).
>
> Britton
>
> On Tue, Mar 1, 2011 at 10:49 AM, j s oishi <jsoishi at gmail.com> wrote:
>
>> 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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>> >
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