arXiv subjects

Ryn Grutkoski

Publications and source records attributed to Ryn Grutkoski.

3 recordsLinked to original sources

arXiv2025

Picture an Astronomer: Best Practices for Retaining Talent in Astrophysics

Women are consistently underrepresented in astrophysics yet are simultaneously subject to disproportionate attrition at every career stage. This disparity between demonstrated efficacy in job performance and ultimate career outcome was the primary motivation for the Picture an Astronomer series, which included both targeted public outreach to increase representation of women in astrophysics and high-level, solution-oriented discussions among professional astronomers. In March 2025, more than 200 astronomers came together in a hybrid-format symposium focused on the state of the field for female scientists, combining scientific exchange with discussions of policies and practices to strengthen retention of talent in the field. This white paper is the result of those discussions, offering a wide range of recommendations developed in the context of gendered attrition in astrophysics but which ultimately support a healthier climate for all scientists alike.

astro-ph.IM↗

arXiv2025

The Effect of Nonlinear Gravity on the Cosmological Background During Preheating

We use numerical relativity to study the violent preheating era at the end of inflation. This epoch can result in highly nonlinear fluctuations in density and gravitational potential which feed back onto the averaged expansion rate -- an effect known as backreaction. Usually, simulations of preheating use the Friedmann constraint to enforce the Hubble expansion of spacetime during the evolution. In numerical relativity, this is not required and the inhomogeneous spacetime is evolved self-consistently. For a 'vanilla' preheating model, we find a violation of the Friedmann constraint at the level of $0.005\%$ over the entire simulation. This violation increases to $\sim10\%$ as we sample smaller scales in the simulation domain.

astro-ph.CO↗

arXiv2023

Gauge preheating with full general relativity

We study gauge preheating following pseudoscalar-driven inflation in full general relativity. We implement the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) scheme to solve the full nonlinear evolution of the metric alongside the dynamics of the pseudoscalar and gauge fields. The dynamics of the background and emission of gravitational waves are broadly consistent with simulations in a Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) spacetime. We find large, localized overdensities in the BSSN simulations of order $\delta = \delta\rho/\rho \sim 30$, and the dimensionless power spectrum of $\delta$ peaks above unity. These overdense regions are seeded on length scales only slightly smaller than the horizon, and have a compactness $C \sim 0.1$. The scale of peak compactness is shorter than the Jeans length, which implies that pressure of the matter fields plays an important role in the evolution of these objects.

astro-ph.CO↗