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Cosmic Pathfinders Program Activities

Cosmic Chatter Series

DATE

Apr 18, 2024

TIME

3:00 pm EST

COMMUNITY

Cosmic Pathfinders

TYPE

Seminar

Simulating Weak Gravitational Lensing in the Roman Space Telescope Using JWST Observed Galaxies

Amethyst Barnes (NASA GSFC/SURA, Roman Space Telescope Post-Bac)

Some of the most perplexing mysteries of our Universe are connected to the energy and matter we have been unable to physically observe. Making up about 95% of the Universe, dark energy and dark matter do not emit, absorb, nor reflect any portion of the electromagnetic spectrum, and their existence is only inferred through their effects on the visible matter. For example, gravitational lensing is a phenomenon that refers to the magnification and shearing induced on light from distant galaxies caused by the gravitational potential of foreground matter. The amount of lensing is directly related to the total amount of matter present, not just the matter that emits light. Weak gravitational lensing, when these distortions are not as noticeable, allows for the entirety of the “cosmic web,” or large-scale structure, to be probed during dark matter searches instead of just the areas we know are dense with matter (i.e., galaxy clusters). To properly measure weak lensing effects, accurate galaxy shape measurements that can be calibrated with simulations are required. The Nancy Grace Roman Space Telescope is the next upcoming NASA flagship mission. One of its main goals is elucidating the nature of dark matter and dark energy via ultra-wide field UV-NIR imaging surveys. Roman’s view is 100 times that of the Hubble Space Telescope, and we will be primed to measure large-scale structure in the context of weak lensing studies. In this poster, I will present our efforts to simulate JWST observed galaxies through the eyes of Roman. I will detail how we remove the PSF from a JWST NIRCam imaged galaxy and add Roman filters and detector effects. We report the comparison between JWST and simulated Roman imaging and place our results in the context of future weak lensing searches with Roman.

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An illustration of Sun-like star HD 181327 and its surrounding debris disk. The star is at top right. It is surrounded by a far larger debris disk that forms an incomplete ellpitical path and is cut off at right. There’s a huge cavity between the star and the disk. The debris disk is shown in shades of light gray. Toward the top and left, there are finer, more discrete points in a range of sizes. The disk appears hazier and smokier at the bottom. The star is bright white at center, with a hazy blue region around it. The background of space is black. The label Artist's Concept appears at lower left.