Chromatic Biases Challenge Roman Telescope’s Weak Lensing Precision

Astronomy

Chromatic Biases Challenge Roman Telescope’s Weak Lensing Precision

Assessing and correcting chromatic biases in Roman Space Telescope shear measurements

From

Arxiv

Weak gravitational lensing studies with the Roman Space Telescope require precise control of chromatic biases caused by differences in galaxy and star colors affecting the point spread function (PSF). This research quantifies these biases and develops correction methods to meet stringent mission requirements.

Why it matters: Chromatic biases can exceed Roman's strict shear measurement limits, risking inaccurate cosmological conclusions.

The big picture: First-order PSF corrections suffice for weak lensing bands, but wide filters need higher-order adjustments.

Stunning stat: Multiplicative shear biases in wide filters reach up to 6%, far above the mission's 0.032% requirement.

Quick takeaway: Both color-based analytic methods and self-organizing maps effectively reduce chromatic biases in PSF modeling.