arXiv subjects

Anthony Girmenia

Publications and source records attributed to Anthony Girmenia.

2 recordsLinked to original sources

arXiv2026

Increasing Sensitivity to Trailed Solar System Objects in Archival JWST NIRCam Imaging with Group Differencing

The JWST archive contains thousands of NIRCam exposures distributed across the sky. Small solar system bodies (SSSBs) are present in many of these fields, but are often trailed and more difficult to detect. The standard pipeline produces a single image by fitting a slope to a sequence of $N$ cumulative ``up-the-ramp" groups of the detector. Thus, each JWST image comprises a time series of cumulative reads. We demonstrate that transforming the ramp into a series of group difference images reduces the per-image trail length of moving sources, producing an $(N-1)$-group photometrically calibrated time series from an $N$-group integration. This enables higher-cadence trajectory-based searches using as few as a single JWST exposure. A generalized least-squares fit of the group difference images along the trajectory of a moving source recovers the source flux at higher SNR when compared to the ramp fit, with the improvement scaling with the reduction in trailing. We validate our procedure on 13 moving objects detected in archival JWST NIRCam images. To estimate our sensitivity increase, we perform an injection/recovery simulation on the JWST imagery. Trailed moving objects recovered via group differencing show higher SNRs, improving completeness to moving sources compared to standard calibrations. For typical integration lengths of $N=4$ or $6$ for archival JWST/NIRCam exposures in the ecliptic, group differencing yields sensitivity gains between $\sim 1.1$--$1.4$ mag, based on simulation results. This method significantly increases the sensitivity of archival JWST surveys to trailed SSSBs.

astro-ph.IM↗

arXiv2026

How Late Solid Enrichment Shapes Atmospheric Abundances in Giant Planets

Atmospheric abundance measurements of giant exoplanets are increasingly used to infer their formation histories, motivating upcoming population studies with facilities such as the ESA Ariel mission. We present a population synthesis study of giant planet formation that combines pebble accretion, planetesimal formation with migration driven accretion, and an inheritance based chemistry model. We compare disks in which angular momentum transport is dominated either by turbulent viscosity or by magnetically driven disk winds. Wind-driven disks produce systematically more massive giant planets, but the atmospheric composition of those planets is otherwise similar to that of planets formed in viscous disks. In the absence of significant late-time solid pollution, atmospheric abundances such as C/H, O/H, and C/O retain sensitivity to the formation and migration history of simulated planets. When planetesimals efficiently enrich the envelope during migration, the abundance distributions collapse onto narrower sequences that are largely insensitive to the underlying disk accretion model. They remain correlated with formation and migration history, though with a smaller dynamic range in abundance. The resulting C/O distributions depend on planet mass in a way that agrees qualitatively well with observations, while the predicted range of C/H and O/H abundances is substantially narrower than observed. This suggests that there is a greater range in the amount of envelope pollution than represented in this simple model.

astro-ph.EP↗