The Nancy Grace Roman Space Telescope Coronagraph Instrument will be the first high-performance stellar coronagraph using active wavefront control for deep starlight suppression in space, enabling the detection of faint interplanetary dust structures present in the habitable zone of nearby (within 10 pc) Sun-like stars. Simulations at 0.03 AU resolution of dust disks at 10 pc have been produced by the Science Investigation Team, with resampled 21 mas pixels, and convolved with publicly available field-dependent PSFs of the Roman Space Telescope Coronagraph Instrument Hybrid Lyot Coronagraph (HLC) mask and Wide Field of View Shaped Pupil Coronagraph (SPCWIDE) mask designs. The resulting simulation files are appropriate for insertion into simulated observing scenarios for the Roman Space Telescope Coronagraph Instrument, and cover two possible types of disks: narrow disk rings similar to the circumstellar debris disk HR 4796A, and disk annuli with radial dust density power-laws that approximate the density distribution of the Solar System zodiacal cloud (Kennedy et al. 2015, ApJS, 216, 23).
Both types of disks are then scaled to a surface brightness in V of 22.5 magnitudes per square arcsecond at the peak surface brightness of the given disk in a face-on (inclination=0 degrees) configuration. The models have a range of inner radii of the disks. The vertical density distribution of the disk is approximated by a Gaussian with a vertical full width at half-maximum of 0.2*R AU, where R is the radial distance from the star.
The dust in the disks is assumed to have a scattering phase function equivalent to the dust in Saturn's G ring (Hedman & Stark 2015, ApJ, 811, 67).
The exact mass of dust in these models is not set, since the precise optical properties of exo-zodiacal dust disks are currently highly uncertain. However, the scaling is appropriate for the surface brightness of the zodiacal cloud at 1 AU.
Convolved images were constructed using the field-dependent PSFs appropriate for each type of mask, and are publicly available at IPAC at Roman Space Telescope Coronagraph Instrument Off-axis PSFs for HLC narrow FOV imaging mode . The HLC convolutions were validated against Observing Scenario 6 (OS6).
Point sources with flux ratios of 10-8 and 3x10-9, respectively, were convolved at 3.5 and 4.5 λ/D, and their core photometry was compared to the noiseless OS6 images (both with and without model uncertainty factors; MUFs), and verified to be consistent within a few percent of OS6 simulations when scaled by the reported integrated stellar flux (stellar flux value used: 1.15x108 photons/s for a V=5 Vega mag G0 star).
Users interested in making use of self-consistent dust disk models are encouraged to use the radiative transfer models that include IR SEDs and images from the archival WFIRST Preparatory Science Project: The Circumstellar Environments of Exoplanet Host Stars (PI: C. Chen, 2010). While these models are more limited in geometry and are based on OS6, they can still provide a useful foundation to explore how surface brightness relates to disk mass.
The simulated ring model data can be downloaded here. The simulated zodi model data can be downloaded here. Detailed information on the data products, along with further explanation of the simulation workflow, can be found in this README file. The instrument parameters used in these simulations are from Cycle 6.