Hang, Qianjun;
Joachimi, Benjamin;
Charles, Eric;
Crenshaw, John Franklin;
Larsen, Patricia;
Malz, Alex;
Schmidt, Sam;
... Zhang, Tianqing; + view all
(2024)
Impact of survey spatial variability on galaxy redshift distributions and the cosmological 3 x 2-point statistics for the Rubin Legacy Survey of Space and Time (LSST).
Monthly Notices of the Royal Astronomical Society
, 535
(4)
pp. 2970-2997.
10.1093/mnras/stae2519.
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Abstract
We investigate the impact of spatial survey non-uniformity on the galaxy redshift distributions for forthcoming data releases of the Rubin Observatory Legacy Survey of Space and Time (LSST). Specifically, we construct a mock photometry data set degraded by the Rubin OpSim observing conditions, and estimate photometric redshifts of the sample using a template-fitting photo-z estimator, BPZ, and a machine learning method, FlexZBoost. We select the Gold sample, defined as for 10 yr LSST data, with an adjusted magnitude cut for each year and divide it into five tomographic redshift bins for the weak lensing lens and source samples. We quantify the change in the number of objects, mean redshift, and width of each tomographic bin as a function of the coadd i-band depth for 1-yr (Y1), 3-yr (Y3), and 5-yr (Y5) data. In particular, Y3 and Y5 have large non-uniformity due to the rolling cadence of LSST, hence provide a worst-case scenario of the impact from non-uniformity. We find that these quantities typically increase with depth, and the variation can be at extreme depth values. Using Y3 as an example, we propagate the variable depth effect to the weak lensing pt analysis, and assess the impact on cosmological parameters via a Fisher forecast. We find that galaxy clustering is most susceptible to variable depth, and non-uniformity needs to be mitigated below 3 per cent to recover unbiased cosmological constraints. There is little impact on galaxy-shear and shear-shear power spectra, given the expected LSST Y3 noise.
| Type: | Article |
|---|---|
| Title: | Impact of survey spatial variability on galaxy redshift distributions and the cosmological 3 x 2-point statistics for the Rubin Legacy Survey of Space and Time (LSST) |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stae2519 |
| Publisher version: | https://doi.org/10.1093/mnras/stae2519 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons License. The images or other third-party material in this article are included in the Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | Science & Technology, Physical Sciences, Astronomy & Astrophysics, techniques: photometric, large-scale structure of Universe, cosmology: observations, DIGITAL SKY SURVEY, PHOTOMETRIC REDSHIFTS, DATA RELEASE, DEEP FIELD, CALIBRATION, SYSTEMATICS, TELESCOPE, MODEL, DENSITY |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10204342 |
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