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README.md
congrid.py
illustris_lightcone_demo.compressed.pdf
illustris_lightcone_demo.ipynb
illustris_lightcone_description.txt
make_color_image.py
render_script.py

README.md

Illustris Mock Deep Fields

Created by Gregory Snyder, Space Telescope Science Institute

On MAST HLSP:

Files with names:

  • hlsp_misty_illustris_jwst-nircam_mag30-fielda-11-10_f150w_v1_lightcone.fits
  • hlsp_misty_sim_telescope-instrument_(field/selection)_filter_version_type.fits

On Central Storage at STScI:

  • /astro/snyder_lab2/Illustris/Lightcones/Lightcone_Catalog_Images/

Demo notebook: https://github.com/gsnyder206/mock-surveys/blob/master/MAST_HLSP/illustris_lightcone_demo.ipynb

Acknowledgements. These are based on the Illustris Project hydrodynamical simulations:

Contents, geometry, and selection:

The filenames indicate the mission, instrument, and filter combination of each image. The geometry/selection of these three fields is derived from the three ``Thin'' lightcones defined in Snyder et al. (2017), for example mag30-fielda-11-10_v1 corresponds to Field A (Thin) from that paper. The string "mag30" refers to the selection of Illustris subhalos included in the mock image. For these files, the selection is based on the rest-frame g-band apparent magnitude of the source, such that g < 30.0.

FITS files contain the following HDUs:

  1. "IMAGE_NOPSF": Raw image without PSF or noise. Header documented below.
  2. "SimulationAssumptions": URL links to Illustris documentation and API.
  3. "MockDataAssumptions": Header contains code and parameter choices for creating mock images.
  4. "IMAGE_PSF" : [Optional] Same image, now convolved with model PSF from TinyTim or WebbPSF.
  5. "MODELPSF" : [Optional] The PSF model at the same pixel scale as HDU 3 "IMAGE_PSF".
  6. "Catalog" : Lightcone Catalog, containing intrinsic simulation info, including galaxy ID numbers, image positions, and other info.
  7. "CatalogDocumentation": Strings containing explainers of catalog columns (same as below)

In HDU 0-"IMAGE_NOPSF", the header contains the following useful cards, for example:

FILTER = 'F160W ' / filter
PIXSIZE = 0.06 / arcsec
UNIT = 'nanoJanskies' / per pixel
ABZP = 31.40006562228223 / AB mag zeropoint
PHOTFNU = 1.52E-07 / Jy; approx flux[Jy] at 1 count/sec
EXTNAME = 'IMAGE_NOPSF'
DOI = 'https://doi.org/10.1093/mnras/stx487'
AUTHOR = 'Gregory F. Snyder'
PAPER = 'Snyder et al. 2017, MNRAS, 468, 207'
DATE = '2017-05-04T15:00:38.186163'
MISSION = 'HST ' / Mission/telescope
INSTR = 'WFC3 ' / Instrument
HIERARCH TELESCOPE = 'HST ' / Mission/telescope
HIERARCH INSTRUMENT = 'WFC3 ' / Instrument
ALLFIL = 'hst-wfc3_f160w'
SIM_NAME= 'Illustris-1'
SIM_DATA= 'http://www.illustris-project.org'
IMTYPE = 'Survey ' / type of image source
REDSHIFT= '0.5-20 ' / Redshift of object or survey

These values, especially PHOTFNU, are highly approximate and should be confirmed by the user using an ETC before applying to any analyses.

For HDUs 3-4, I produced these only for HST and JWST filters, as I have not yet fully propagated the WFIRST filters and PSF characteristics. These might be a good test bed for "in-situ" data simulation methods. Also it might make sense to wait for the hardware to stabilize a bit more before fully installing these assumptions in a pipeline.

For HDU 5, here is the column documentation:

  • 'snapshot' Illustris snapshot number
  • 'SubfindID' Illustris subhalo Subfind ID number
  • 'ra_deg' arbitrary right ascension in degrees
  • 'dec_deg' arbitrary declination in degrees
  • 'ra_kpc' arbitrary x offset in physical kpc at true redshift
  • 'dec_kpc' arbitrary y offset in physical kpc at true redshift
  • 'ra_kpc_inferred' same as previous but for inferred redshift
  • 'dec_kpc_inferred' --
  • 'true_z' true cosmological redshift
  • 'inferred_z' inferred cosmological redshift (true z + peculiar v/c)
  • 'peculiar_z' peculiar v/c
  • 'true_kpc_per_arcsec' kpc per arcsec at true redshift
  • 'X_cmpc' galaxy X position in observer frame [comoving Mpc]
  • 'Y_cmpc' galaxy Y position in observer frame [comoving Mpc]
  • 'Z_cmpc' galaxy Z position in observer frame [comoving Mpc]
  • 'ADD_cmpc' angular diameter distance at true redshift [comoving Mpc]
  • 'ADD_cmpc_inferred' angular diameter distance at inferred redshift [comoving Mpc]
  • 'snapshot_z' redshift of Illustris snapshot from which this subhalo is drawn
  • 'geometric_z' estimated redshift at the comoving distance in the center of the lightcone path through this snapshot
  • 'cylinder_number' index of snapshot repetition for this subhalo
  • 'mstar_msun_rad' stellar mass in 2X stellar half-mass radius [Msun]
  • 'mgas_msun_rad' gas mass in 2X stellar half-mass radius [Msun]
  • 'subhalo_mass_msun' total mass in subhalo [Msun]
  • 'bhmass_msun_rad' supermassive black hole mass in 2X stellar half-mass radius [Msun]
  • 'mbary_msun_rad' total baryon mass in 2X stellar half-mass radius [Msun]
  • 'sfr_msunperyr_rad' SFR in 2X stellar half-mass radius [Msun]
  • 'bhrate_code' supermassive black hole accretion rate in code units (see data release docs)
  • 'camX_mpc' galaxy X position in camera frame [physical Mpc]
  • 'camY_mpc' galaxy Y position in camera frame [physical Mpc]
  • 'camZ_mpc' galaxy Z position in camera frame [physical Mpc]
  • 'g_AB_absmag' rest-frame SDSS-g AB absolute magnitude
  • 'r_AB_absmag' rest-frame SDSS-r AB absolute magnitude
  • 'i_AB_absmag' rest-frame SDSS-i AB absolute magnitude
  • 'z_AB_absmag' rest-frame SDSS-z AB absolute magnitude
  • 'v_kms_camX' transverse x velocity [km/s]
  • 'v_kms_camY' transverse y velocity [km/s]
  • 'v_kms_camZ' line-of-sight (peculiar) velocity [km/s]
  • 'v_kms_hubble' true cosmological expansion velocity [km/s]
  • 'g_AB_appmag' rest-frame SDSS-g AB apparent magnitude
  • 'sim' simulation name (e.g., 'Illustris-1')
  • 'snap' Illustris snapshot number (same as 'snapshot')
  • 'sfid' Illustris subhalo Subfind ID number (same as 'SubfindID')
  • 'z' true cosmological redshift (same as 'true_z')
  • 'RA' same as 'ra_deg'
  • 'DEC' same as 'dec_deg'
  • 'origin_i' Internal variable describing the image array location to place the origin of this galaxy's image [Internal-- does not describe final image]
  • 'origin_j' Internal variable describing the image array location to place the origin of this galaxy's image [Internal-- does not describe final image]
  • 'pos_i' position of this subhalo in array rows [it appears that (pos_j,pos_i) is the correct placement in Python terms] [Internal-- does not describe final image]
  • 'pos_j' position of this subhalo in array columns [it appears that (pos_j,pos_i) is the correct placement in Python terms] [Internal-- does not describe final image]
  • 'pixsize_arcsec' pixel size of image [Arcsec-- Internal--does not describe final image]
  • 'final_fov_arcsec' final field-of-view of image [Arcsec]
  • 'full_npix' total number of pixels across image [Internal-- does not describe final image]
  • 'this_npix' number of pixels in this galaxy's sub-image [Internal-- does not describe final image]
  • 'this_fov_kpc' field-of-view of this galaxy's image in physical kpc
  • 'halfmassrad_factor' factor describing this galaxy's field of view in units of its stellar half-mass radius
  • 'nrays' number of rays used to render this galaxy's image
  • 'run_dir' internal run directory for locating this galaxy's sub-image
  • 'success' whether or not this galaxy is rendered in the final image (should all be True; Falses were dropped from this table before saving)
  • 'new_i' position of galaxy in image pixel units [final version-- use this one] [it appears that (pos_j,pos_i) is the correct placement in Python terms]
  • 'new_j' position of galaxy in image pixel units [final version-- use this one] [it appears that (pos_j,pos_i) is the correct placement in Python terms]
  • 'AB_absmag_jwst-nircam_f200w' (example name only) observed-frame perfectly measured total absolute magnitude in this filter for this galaxy [AB units]