The SuperMock synthetic sky from HACC

About this view

• Source: SuperMock dataset on – deg² area of the sky (lightcone patch). Catalog consists of a wide number of simulation quantities (from HACC — LastJourney, arXiv:2006.01697) like dark matter mass accretion histories and halo masses, along with synthetic observations like narrow-band spectra and photometry. See: github.com/nesar/SuperMockLoad.
• Shapes and sizes: the mock catalog has no morphology, Sersic index or orientation per galaxy. Disk-vs-spheroid type, size and viewing angle are assigned from plausible scaling relations (mass→size, SPHEREx 4.0−1.2 µm color→disk/spheroid), then rendered once each into a 16-tile texture atlas with GalSim (Sersic n=1/n=4 profiles, hand-added spiral arm/clump texture, Gaussian PSF) — the same procedural recipe used for the deep-field zoom panel in the static money-plot figures. Sizes of the galaxies are also illustrative. They do not correspond to physical sizes, however the relative sizes are based on the catalog.
• Selections: the visible number density looks roughly uniform along the line of sight even though the true number of galaxies per shell varies by ~4 orders of magnitude. For every 50 Mpc shell, we cap the galaxies to 5000, reducing the visualization of over 70M galaxies to around 800K.
• Colors: blue→red tint follows each mock galaxy's SPHEREx mid-IR color (redder = dustier/more quiescent).
• Telescope views: LSST/WISE/SPHEREx buttons use each survey's magnitude against that survey's 5σ depth — a galaxy only appears if it actually clears that depth.
• Credits: this visualization was inspired by knowtheuniverse.com, which was done on the real data from the 2MASS Redshift Survey. Anthropic Fable-5.1 was utilized in the visualization.