Bard College

Searching for signs of life is a primary goal of the Habitable Worlds Observatory (HWO). However, merely detecting oxygen, methane, or other widely discussed biosignatures is insufficient evidence for a biosphere. In parallel with biosignature detection, exoplanet life detection additionally requires characterization of the broader physicochemical context to evaluate planetary habitability and the plausibility that life could produce a particular biosignature in a given environment. Life detection further requires that we can confidently rule out photochemical or geological phenomena that can mimic life (i.e., "false positives"). Evaluating false-positive scenarios may require different observatory specifications than biosignature detection surveys. Here, we explore the coronagraph requirements for assessing habitability and for cautiously excluding known false-positive (and false-negative) scenarios for oxygen and methane, the two most widely discussed biosignatures for Earth-like exoplanets. We find that broad wavelength coverage ranging from the near ultraviolet (UV; 0.26 µm) and extending into the near infrared (NIR; 1.7 µm) is necessary to contextualize these potential biosignatures with HWO. The short-wavelength cutoff is driven by the need to identify Proterozoic-like biospheres via O3, whereas the long-wavelength cutoff is driven by the need to contextualize O2 and CH4 biosignatures via constraints on carbon-bearing atmospheric species. The ability to obtain spectra with signal-to-noise ratios of 20-40 across this 0.26-1.7 µm range (assuming R = 7 UV, R = 140 VIS, and R = 70 NIR) is also required. While not every Earth-analog biosignature and false positive can be unambiguously identified with these capabilities-and the plausibility and contextual clues of many biosignature false positives remain an area of active research-our minimal spectral recommendations would enable a broad search for Earth-like life assuming such observations are achievable for a statistically meaningful number of HWO targets.

We present the Data Quality Report Builder toolkit, DQRbuild, a suite of data quality tools that have been developed to vet gravitational-wave events in preparation for the fourth LIGO-Virgo-KAGRA observing run. We explain the main functionality and the many scientific tests that we support. To validate the performance of the tools included in the toolkit, we run a series of tests on all significant candidates shared as public alerts in the third observing run to compare against what was manually reported using human intervention. We find that these automated tools can now identify 96

Periodically driven quantum systems can host nonequilibrium phenomena without static analogs, including in their entanglement dynamics. Here, we discover temporal entanglement transitions (TETs) in a Floquet spin chain, which correspond to a quantum phase transition in the spectrum of the entanglement Hamiltonian and are signaled by dynamical spontaneous symmetry breaking. We identify the symmetry principles underlying these transitions: they appear when the driven Hamiltonian preserves global symmetry (here, Z_{2}), the initial state respects this symmetry, and the reduced density matrix carries weight in both subsystem-parity sectors, with TETs occurring precisely when the sector weights become equal (given the previous two conditions are also satisfied). Intriguingly, we find these transitions across a broad range of driving frequencies (from adiabatic to high-frequency regime) and independent of drive details, where they manifest as periodic, sharp entanglement spectrum reorganizations marked by the Schmidt-gap closure, a vanishing entanglement echo, and symmetry-quantum-number flips, while remaining invisible to conventional local observables. At high frequencies, the entanglement Hamiltonian acquires an intrinsic timescale decoupled from the drive period, rendering the transitions genuine steady-state features. Finite-size scaling reveals universal critical behavior with correlation-length exponent ν=1, matching equilibrium Ising universality despite its emergence from purely dynamical mechanisms decoupled from static criticality. Our Letter establishes TETs as novel features in Floquet quantum matter.

Fermionic topological orders can host 't Hooft anomalies with no bosonic counterpart. We identify a new sixteen-fold family of (2+1)D fermionic topological orders, forming a fermionic analogue of Kitaev's sixteen-fold way. This family is distinguished by the mod 16 't Hooft anomaly of a ℤ_2 one-form symmetry, generated in each theory by a single nontrivial ℤ_2 anyon. This intrinsically fermionic anomaly permits anyon spins that are forbidden in bosonic phases; the simplest new example is an Abelian fermionic topological order containing a single ℤ_2 Abelian anyon of spin 1/8. Each theory can be realized as the gapped boundary of a (3+1)D fermionic symmetry-protected topological (SPT) phase protected by the ℤ_2 one-form symmetry, which acquires a ℤ_16 classification once the spacetime spin structure is twisted by the one-form symmetry. We realize these phases microscopically via lattice models built from Walker-Wang models coupled to local fermions.

Pulsed resources, including mast production by forest trees, often have knock-on effects on consumer populations and their prey, predators, parasites and mutualists. Response by small rodents to fluctuating acorn production in temperate forests is a widespread example. Long-term research in Maine, USA, recently suggested combined effects of a warming climate and forest maturation on acorn production by red oak trees, leading to directional increases in average population density and body mass of white-footed mice. To foster reproducibility in long-term ecological research, we analysed data from our long-term study in southeastern New York, USA, which used similar field methods. Such a comparison allowed us to assess impacts of climate warming and forest growth on the same pulsed resource and responses by the same consumer species over time and at different latitudes. Despite a clear directional increase in mean minimum temperature and considerable growth in the average size and total basal area of trees during our 33-year study, neither acorn production by red oak trees nor abundance of white-footed mice showed directional increases. Similarly, average body mass of the mice did not change through time. Abundance of mice in mid-summer increased with increasing red oak acorn production the prior autumn. Mouse abundance also was higher in warmer years, although the effect of acorn abundance on mice was stronger. We found no evidence that temperature modified the acorn-driven population responses by mice. Long-term studies are notoriously hard to maintain and even harder to replicate between sites. The direct comparison of similar studies between Maine and New York provides an opportunity to assess the generality of mechanistic models linking climate change, mast seeding and consumer responses.