arXiv subjects

Ryan Wills

Publications and source records attributed to Ryan Wills.

4 recordsLinked to original sources

arXiv2026

Observations of Atmospheric Helium and Oxygen with SPHEREx

We present measurements of near-infrared (NIR) terrestrial airglow produced by helium and oxygen in the exosphere as observed by SPHEREx. Using eight months of survey data obtained from a 680 km low-Earth orbit, emission from HeI $\lambda$10830, OI $\lambda$8446, and OI $\lambda$11287 is mapped with both global spatial and multi-season temporal coverage. These measurements are obtained along upward looking lines of sight as part of the astrophysical survey, in contrast to conventional nadir-viewing Earth remote sensing, which probes the behavior of low-density material in the thermo- and exosphere. We describe an analytical framework to extract atmospheric emission lines in the presence of astrophysical backgrounds including stars, resolved galaxies, and the diffuse Zodiacal light. The resulting global measurements reveal temporal variability over the survey period and systematic dependencies on geographic location. We interpret these variations in the context of the variable Solar illumination and seasonal effects. SPHEREx, an astrophysical space observatory, is demonstrated to be a promising new platform for monitoring NIR airglow and investigating its coupling to Solar activity and global geophysical processes.

physics.ao-ph↗

arXiv2025

Measuring the Temperature of Extremely Hot Shock-Heated Gas in the Major Merger MACS J0717.5+3745 With Relativistic Corrections to the Sunyaev-Zel'dovich Effect

The conversion of gravitational potential to kinetic energy results in an intracluster medium (ICM) gas with a characteristic temperature near 10 keV in the most massive galaxy clusters. X-ray observations, primarily from Chandra and XMM-Newton, have revealed a wealth of information about the thermodynamics of this gas. However, two regimes remain difficult to study with current instruments: superheated gas well above 10 keV generated by shocks from major mergers, and distant systems strongly impacted by cosmological dimming. Relativistic corrections to the Sunyaev-Zel'dovich effect (rSZe) produce a fractional spectral distortion in the cosmic microwave background at submillimeter and millimeter wavelengths that could offer a complementary probe of both high-temperature and high-redshift ICM gas. Here we describe multiband measurements of the rSZe, including observations from the Fourier Transform Spectrometer on the Herschel-SPIRE instrument, that constrain the ICM thermodynamics of the major merger MACS J0717.5+3745. Within the seven observed lines of sight, we find an average temperature of $T_{\mathrm{rSZe}}=15.1^{+3.8}_{-3.3}$ keV which is consistent with the values obtained from X-ray measurements of the same regions, with $T_{\mathrm{Chandra}}=18.0^{+1.1}_{-1.1}$ keV and $T_{\mathrm{XMM}}=13.9^{+0.9}_{-0.9}$ keV. This work demonstrates that the rSZe signal can be detected with moderate spectral resolution submillimeter data, while also establishing the utility of such measurements for probing superheated regions of the ICM.

astro-ph.GA↗

arXiv2025

CIBER 4th flight fluctuation analysis: Measurements of near-IR auto- and cross-power spectra on arcminute to sub-degree scales

We present new anisotropy measurements in the near-infrared (NIR) for angular multipoles $300<\ell<10^5$ using imaging data at 1.1 $\mu$m and 1.8 $\mu$m from the fourth flight of the Cosmic Infrared Background ExpeRiment (CIBER). Using improved analysis methods and higher quality fourth flight data, we detect surface brightness fluctuations on scales $\ell<2000$ with CIBER auto-power spectra at $\sim14\sigma$ and 18$\sigma$ for 1.1 and 1.8 $\mu$m, respectively, and at $\sim10\sigma$ in cross-power spectra. The CIBER measurements pass internal consistency tests and represent a $5-10\times$ improvement in power spectrum sensitivity on several-arcminute scales relative to that of existing studies. Through cross-correlations with tracers of diffuse galactic light (DGL), we determine that scattered DGL contributes $<10\%$ to the observed fluctuation power at high confidence. On scales $\theta > 5'$, the CIBER auto- and cross-power spectra exceed predictions for integrated galactic light (IGL) and integrated stellar light (ISL) by over an order of magnitude, and are inconsistent with our baseline IGL+ISL+DGL model at high significance. We cross-correlate two of the CIBER fields with 3.6 $\mu$m and 4.5 $\mu$m mosaics from the Spitzer Deep Wide-Field Survey and find similar evidence for departures from Poisson noise in Spitzer-internal power spectra and CIBER $\times$ Spitzer cross-power spectra. A multi-wavelength analysis indicates that the auto-power of the fluctuations at low-$\ell$ is bluer than the Poisson noise from IGL and ISL; however, for $1' <\theta < 10'$, the cross-correlation coefficient $r_{\ell}$ of nearly all band combinations decreases with increasing $\theta$, disfavoring astrophysical explanations that invoke a single correlated sky component.

astro-ph.CO↗

arXiv2024

SPIRE HeRS/HeLMS Combined SHIM Maps

We have regenerated Herschel-SPIRE maps covering 360 square degrees near the celestial equator. These are the largest extragalactic surveys designed to overlap with cosmic microwave background legacy fields mapped at sub-mm wavelengths. We provide documentation detailing their construction and use. The maps are available on zenodo as https://doi.org/10.5281/zenodo.13352296.

astro-ph.CO↗