Search for: All records

Abstract The ocean carbon reservoir controls atmospheric carbon dioxide (CO₂) on millennial timescales. Radiocarbon (¹⁴C) anomalies in eastern North Pacific sediments suggest a significant release of geologic¹⁴C‐free carbon at the end of the last ice age but without evidence of ocean acidification. Using inverse carbon cycle modeling optimized with reconstructed atmospheric CO₂and¹⁴C/C, we develop first‐order constraints on geologic carbon and alkalinity release over the last 17.5 thousand years. We construct scenarios allowing the release of 850–2,400 Pg C, with a maximum release rate of 1.3 Pg C yr⁻¹, all of which require an approximate equimolar alkalinity release. These neutralized carbon addition scenarios have minimal impacts on the simulated marine carbon cycle and atmospheric CO₂, thereby demonstrating safe and effective ocean carbon storage. This deglacial phenomenon could serve as a natural analog to the successful implementation of gigaton‐scale ocean alkalinity enhancement, a promising marine carbon dioxide removal method. 

NSF ADVANCE has been instrumental in supporting institutional practices leading to the increased representation of women in STEM. However, research suggests institutional culture and practices evolve slowly, and much progress remains to create a collaborative and supportive work environment where women scientists, mathematicians, and engineers can thrive, particularly those with intersectional identities, including women of color and women with caregiving responsibilities. A partnership of four midwestern research universities joined together in late 2019 to adapt, design, implement, and assess the impact of a coordinated suite of programs intended to enhance the career success of women and underrepresented STEM faculty. The programs promote mentoring, male advocacy, and informed and intentional leadership as integral to campus culture, and foster community and cross-institutional data-based collaboration. This paper summarizes the programs designed and implemented to improve retention and job satisfaction of women in STEM fields with a focus on the intersectionalities of women of color and women with family responsibilities, including navigating the challenges presented by the COVID-19 pandemic, by creating support networks for these faculty. 

Gravitational waves provide a unique tool for observational astronomy. While the first LIGO–Virgo catalogue of gravitational wave transients (GWTC-1) contains 11 signals from black hole and neutron star binaries, the number of observations is increasing rapidly as detector sensitivity improves. To extract information from the observed signals, it is imperative to have fast, flexible, and scalable inference techniques. In a previous paper, we introduced BILBY: a modular and user-friendly Bayesian inference library adapted to address the needs of gravitational-wave inference. In this work, we demonstrate that BILBY produces reliable results for simulated gravitational-wave signals from compact binary mergers, and verify that it accurately reproduces results reported for the 11 GWTC-1 signals. Additionally, we provide configuration and output files for all analyses to allow for easy reproduction, modification, and future use. This work establishes that BILBY is primed and ready to analyse the rapidly growing population of compact binary coalescence gravitational-wave signals. 

Abstract Gravitational lensing by massive objects along the line of sight to the source causes distortions to gravitational wave (GW) signals; such distortions may reveal information about fundamental physics, cosmology, and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO-Virgo network. We search for repeated signals from strong lensing by (1) performing targeted searches for subthreshold signals, (2) calculating the degree of overlap among the intrinsic parameters and sky location of pairs of signals, (3) comparing the similarities of the spectrograms among pairs of signals, and (4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by (1) frequency-independent phase shifts in strongly lensed images, and (2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the nondetection of GW lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects.