arXiv subjects

C. McGinn

Publications and source records attributed to C. McGinn.

4 recordsLinked to original sources

arXiv2026

The Carruthers Mission Concept and Performance

The Carruthers Geocoronal Observatory (Carruthers), formerly GLIDE, is a NASA Heliophysics Science Mission of Opportunity implemented through the Solar Terrestrial Probes (STP) Program and launched as a rideshare in September 2025. Carruthers is the first spaceflight mission edicated to continuous global imaging of Earth's hydrogen exosphere through observations of geocoronal Lyman-$\alpha$ emission at 121.6 nm. The observatory operates at distances of 1.3-1.7 million km in a halo orbit about the Sun-Earth L1 point, enabling retrieval of the three-dimensional distribution of atomic hydrogen, the dominant constituent of the exosphere, on hourly timescales and unprecedented spatial resolution. These new data provide the key to understanding processes governing atmospheric escape, geospace coupling, and solar-wind interaction. Carruthers carries the GeoCoronal Imager (GCI), a dual-channel ultraviolet imaging instrument comprising the Narrow-Field Imager (NFI) for high-resolution observations of the inner exosphere and the Wide-Field Imager (WFI) for synoptic imaging of the extended hydrogen halo. Along with a student-provided experiment, the instrument suite is the sole payload aboard a three-axis-stabilized spacecraft designed to support nadir viewing throughout the $\sim178$ day halo orbit about L1. Observations also measure the interplanetary Lyman-$\alpha$ background, enabling separation of heliospheric and geocoronal emissions. The student-led experiment monitors solar Lyman-$\alpha$ and extreme ultraviolet emission during portions of the orbit. Science data are returned through the Deep Space Network at data rates up to 1 Mbit s$^{-1}$. The two-year baseline mission begins in March 2026, with propellant reserves capable of supporting more than ten years of orbit maintenance and maneuvers.

astro-ph.IM↗

arXiv2025

Physics with high-luminosity proton-nucleus collisions at the LHC

The physics case for the operation of high-luminosity proton-nucleus ($pA$) collisions during Run 3 and 4 at the LHC is reviewed. The collection of $\mathcal{O}$(1-10 pb$^{-1}$) of proton-lead ($p$Pb) collisions at the LHC will provide unique physics opportunities in a broad range of topics including proton and nuclear parton distribution functions (PDFs and nPDFs), generalised parton distributions (GPDs), transverse momentum dependent PDFs (TMDs), low-$x$ QCD and parton saturation, hadron spectroscopy, baseline studies for quark-gluon plasma and parton collectivity, double and triple parton scatterings (DPS/TPS), photon-photon collisions, and physics beyond the Standard Model (BSM); which are not otherwise as clearly accessible by exploiting data from any other colliding system at the LHC. This report summarises the accelerator aspects of high-luminosity $pA$ operation at the LHC, as well as each of the physics topics outlined above, including the relevant experimental measurements that motivate -- much -- larger $pA$ datasets.

hep-ph↗

arXiv2019

The Skinny on Bulk Viscosity and Cavitation in Heavy Ion Collisions

Relativistic heavy ion collisions generate nuclear-sized droplets of quark-gluon plasma (QGP) that exhibit nearly inviscid hydrodynamic expansion. Smaller collision systems such as p+Au, d+Au, and $^{3}$He+Au at the Relativistic Heavy Ion Collider, as well as p+Pb and high-multiplicity p+p at the Large Hadron Collider may create even smaller droplets of QGP. If so, the standard time evolution paradigm of heavy ion collisions may be extended to these smaller systems. These small systems present a unique opportunity to examine pre-hydrodynamic physics and extract properties of the QGP, such as the bulk viscosity, where the short lifetimes of the small droplets makes them more sensitive to these contributions. Here we focus on the influence of bulk viscosity, its temperature dependence, and cavitation effects on the dynamics in small and large systems using the publicly available hydrodynamic codes SONIC and MUSIC. We also compare pre-hydrodynamic physics in different frameworks including AdS/CFT strong coupling, IP-GLASMA weak coupling, and free streaming or no coupling.

nucl-th↗

arXiv2018

K2 Observations of SN 2018oh Reveal a Two-Component Rising Light Curve for a Type Ia Supernova

We present an exquisite, 30-min cadence Kepler (K2) light curve of the Type Ia supernova (SN Ia) 2018oh (ASASSN-18bt), starting weeks before explosion, covering the moment of explosion and the subsequent rise, and continuing past peak brightness. These data are supplemented by multi-color Pan-STARRS1 and CTIO 4-m DECam observations obtained within hours of explosion. The K2 light curve has an unusual two-component shape, where the flux rises with a steep linear gradient for the first few days, followed by a quadratic rise as seen for typical SNe Ia. This "flux excess" relative to canonical SN Ia behavior is confirmed in our $i$-band light curve, and furthermore, SN 2018oh is especially blue during the early epochs. The flux excess peaks 2.14$\pm0.04$ days after explosion, has a FWHM of 3.12$\pm0.04$ days, a blackbody temperature of $T=17,500^{+11,500}_{-9,000}$ K, a peak luminosity of $4.3\pm0.2\times10^{37}\,{\rm erg\,s^{-1}}$, and a total integrated energy of $1.27\pm0.01\times10^{43}\,{\rm erg}$. We compare SN 2018oh to several models that may provide additional heating at early times, including collision with a companion and a shallow concentration of radioactive nickel. While all of these models generally reproduce the early K2 light curve shape, we slightly favor a companion interaction, at a distance of $\sim$$2\times10^{12}\,{\rm cm}$ based on our early color measurements, although the exact distance depends on the uncertain viewing angle. Additional confirmation of a companion interaction in future modeling and observations of SN 2018oh would provide strong support for a single-degenerate progenitor system.

astro-ph.HE↗