rbiswas4
commented
9 years ago @sethdigel, Thank you for your comments, they help in putting in required pieces.
The Requirements aspect ideally would be more quantitative, e.g., about what counts as good (enough) temporal and wavelength sampling - maybe that is defined in the metrics. Is good wavelength sampling needed for each SN Ia or is the wavelength sampling requirement to be understood to apply over time, e.g., for determining redshifts of host galaxies?
- Part of the answer is that we do not have a good idea of 'what counts as good' . The metrics (and potentially new metrics) can quantify some intuitive ideas people have about what constitutes good sampling, but mapping such intuitive ideas or metrics to a concrete gain in cosmology has not been explored deeply (as far as I know). This is the investigation we should outline and do.
- Good wavelength sampling (or perhaps better to call it filter coverage?) is needed per SN. When we wrote that statement, we were thinking about the 'color' dependence of the intrinsic brightness of SNIa. However, there is a question about photoz of the host galaxy too, as you point out. And I am not sure if this is something that will be quantified by the photoz group.
We will try to update the document to reflect this additional information.
In terms of Exploring OpSim Outputs, I think that I recall an early study (or possibly folklore) that concluded that only the DDFs were likely to be useful for supernova cosmology in terms of cadence.
This is correct, earlier studies based on previous opsim outputs had found very few SN that were cosmologically well measured in the WFD survey proposal. But, new proposals are coming in, which may be better.
It may be that with dithering of fields for the main sky survey the cadence in regions of overlap may be adequate as well.
The point that you are perhaps recalling is that there are overlaps between pointings to different fields (though it is a small fraction of the field area), leading to higher cadence. With dithering, I would guess (but am far from sure) that the overalap area (and therefore the cadence gain) will decrease, but there could still be some.
I will also clarify this point in the document.
The Science Goals look well stated. The Requirements aspect ideally would be more quantitative, e.g., about what counts as good (enough) temporal and wavelength sampling - maybe that is defined in the metrics. Is good wavelength sampling needed for each SN Ia or is the wavelength sampling requirement to be understood to apply over time, e.g., for determining redshifts of host galaxies?
In terms of Exploring OpSim Outputs, I think that I recall an early study (or possibly folklore) that concluded that only the DDFs were likely to be useful for supernova cosmology in terms of cadence. It may be that with dithering of fields for the main sky survey the cadence in regions of overlap may be adequate as well. Probably that is what could make the large scale structure science goal feasible.