Re: [Yt-dev] Simulated Observations: Request for Corrections

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 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...

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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:

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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

On Tue, Mar 1, 2011 at 7:38 AM, John Wise wrote: they not (SZY and SZ_Kinetic)? Or are those user-derived fields not in public yt?

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cheers,

On Mar 1, 2011, at 10:02 AM, Matthew Turk wrote:

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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@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org

Eric Hallman Google Voice: (774) 469-0278 hallman13@gmail.com

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