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We present version 2.1 of the public code precession, a Python module for studying the post-Newtonian dynamics of precessing black hole binaries. In this release, we extend the code to handle eccentric orbits. This extension leverages the existing numerical infrastructure wherever possible, introducing a semi-automatic method to adapt circular-orbit functions to the eccentric case via a Python decorator. Additional new features include orbit- and precession-averaged evolutionary equations for the eccentricity, as well as revised expressions to convert between post-Newtonian separation and gravitational-wave emission frequency.

The Asian summer monsoon (ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM. (1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated ~100 kyr (thousand years) periodicity, while the cave oxygen-isotope ( δ 18 O) records reveal periodicity in an almost pure precession band (~20 kyr periodicity)—the “Chinese 100 kyr problem”. (2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8–10 kyr to Northern Hemisphere summer insolation (NHSI), whereas the Asian cave δ 18 O records follow NHSI without a significant lag—a discrepancy termed the “sea-land precession-phase paradox”. How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the “Chinese 100 kyr problem“ and “sea-land precession-phase paradox”.

The coalescence of black-hole binaries provides a unique arena for testing general relativity in the dynamical and strong-field regime. The ringdown phase, where the merger remnant relaxes to a stationary state, offers a direct probe of the theory. It is dominated by the oscillation frequencies of the remnant, the so-called quasinormal modes, which reveal the nature of the remnant. We present a parametrized test of general relativity that constrains deviations in the quasinormal modes for spin-precessing binaries. We show that neglecting spin precession can lead to false detections of GR deviations, even at current detector sensitivities, emphasizing the need for accurate modeling. Finally, we reanalyze the events of the third Gravitational-Wave Transient Catalog. Using a hierarchical combination of these events, we accurately constrain fractional deviations in the frequency and damping time of the dominant quasi-normal mode.

We investigate the spin-Hall conductivity (SHC) in the two-dimensional spin–orbit coupled systems by taking spin precession into account. The influence of spin precession on the spin-Hall current in the presence of disorder is investigated. Perturbation method leads to the result that the spin dynamics is composed of Larmor (periodic) and non-Larmor (non-periodic) precession. The non-Larmor component of spin is found to be the same result obtained from the Kubo formula in the short time limit. The Larmor component of spin, i.e., spin precession in the unperturbed system, was neglected in the previous studies, but it plays an important role in the linear response theory. The Larmor precession of spin should be zero after time average over several complete periods because there is no specific orientation perpendicular to the plane. By using the requirement of vanishing time-averaged Larmor precession of spin, we calculate the time-averaged non-Larmor SHC for k -cubic Rashba system by using the conventional definition of the spin current. Our result is 2.1( q /8 π ) which is very close to the experimental value 2.2( q /8 π ) by Wunderlich et al [2005 Phys. Rev. Lett. 94 , 047204], where − q is the electric charge.

We study the internal and external alignment of carbonaceous grains in the interstellar medium (ISM) within the Radiative Torque (RAT) paradigm. For internal alignment (IA), we find that hydrogenated amorphous carbon (HAC) grains having nuclear paramagnetism due to hydrogen protons have efficient nuclear relaxation, whereas both HAC and graphite grains can have efficient inelastic relaxation at both low-J and high-J attractors. For external alignment, HAC and pure graphite grains can align with the radiation direction (k-RAT) at low-J attractors but cannot have stable alignment at high-J attractors due to the suppression of radiative precession. However, HAC grains can align with the magnetic field (B-RAT) at high-J attractors due to fast Larmor precession compared to gas collisions. For HAC grains drifting through the ISM, they can align along the induced electric field (E-RAT) at low-J attractors due to the fast electric precession and only small HAC grains can align at high-J attractors. Nuclear paramagnetic relaxation is inefficient for HAC due to the suppression of nuclear susceptibility. We then study the alignment of carbon dust in the envelope of a C-rich Asymptotic Giant Branch star (IRC+10216) and find that grains aligned at low-J attractors may occur via k-RAT with the wrong IA in the inner region but via B-RAT in the outer region. However, grains aligned at high-J attractors have the right IA alignment via k-RAT due to efficient inelastic relaxation. The polarization pattern observed toward IRC+10216 by SOFIA/HAWC+ can be reproduced when only grains at low-J attractors are present due to the removal of grains at high-J attractors by the RAT disruption.

Excitons in Transition Metal Dichalcogenides (TMDs) acquire a spin-like quantum number, a pseudospin, originating from the crystal’s discrete rotational symmetry. Here, we break this symmetry using a tunable uniaxial strain, effectively generating a pseudomagnetic field acting on exciton valley degree of freedom. Under this field, we demonstrate pseudospin analogs of spintronic phenomena such as the Zeeman effect and Larmor precession and determine fundamental timescales for pseudospin dynamics in TMDs. Finally, we uncover the bosonic – as opposed to fermionic – nature of many-body excitonic species using the pseudomagnetic equivalent of the g -factor spectroscopy. Our work is the first step toward establishing this spectroscopy as a universal method for probing correlated many-body states and realizing pseudospin analogs of spintronic devices. Here, the authors break the symmetry of atomically thin transition metal dichalcogenides using a tunable uniaxial strain, and demonstrate pseudospin analogs of spintronic phenomena such as the Zeeman effect and Larmor precession.

The nearby radio galaxy M87 offers a unique opportunity to explore the connections between the central supermassive black hole and relativistic jets. Previous studies of the inner region of M87 revealed a wide opening angle for the jet originating near the black hole 1 – 4 . The Event Horizon Telescope resolved the central radio source and found an asymmetric ring structure consistent with expectations from general relativity 5 . With a baseline of 17 years of observations, there was a shift in the jet’s transverse position, possibly arising from an 8- to 10-year quasi-periodicity 3 . However, the origin of this sideways shift remains unclear. Here we report an analysis of radio observations over 22 years that suggests a period of about 11 years for the variation in the position angle of the jet. We infer that we are seeing a spinning black hole that induces the Lense–Thirring precession of a misaligned accretion disk. Similar jet precession may commonly occur in other active galactic nuclei but has been challenging to detect owing to the small magnitude and long period of the variation. This study analyses radio observations of the jet in galaxy M87, from which the existence of a spinning black hole that induces Lense–Thirring precession of a misaligned accretion disk is inferred.

Forcing the East Asian summer monsoonWhat factors have controlled the intensity of the East Asian summer monsoon over the recent geological past? To answer this key question requires a robust proxy for rainfall amounts. Beck et al. measured the beryllium isotopic content of loess from China, from which they reconstructed a 550,000-year-long record of rainfall. Rainfall correlated with orbital precession and global variations in ice volume. This finding suggests that the monsoon is governed by low-latitude interhemispheric gradients in solar radiation levels, rather than by high-northern-latitude solar radiation levels as previously suggested.Science, this issue p. 877Cosmogenic 10Be flux from the atmosphere is a proxy for rainfall. Using this proxy, we derived a 550,000-year-long record of East Asian summer monsoon (EASM) rainfall from Chinese loess. This record is forced at orbital precession frequencies, with higher rainfall observed during Northern Hemisphere summer insolation maxima, although this response is damped during cold interstadials. The 10Be monsoon rainfall proxy is also highly correlated with global ice-volume variations, which differs from Chinese cave δ18O, which is only weakly correlated. We argue that both EASM intensity and Chinese cave δ18O are not governed by high-northern-latitude insolation, as suggested by others, but rather by low-latitude interhemispheric insolation gradients, which may also strongly influence global ice volume via monsoon dynamics.

The general-relativistic phenomenon of spin-induced orbital precession has not yet been observed in strong-field gravity. Gravitational-wave observations of binary black holes (BBHs) are prime candidates, as we expect the astrophysical binary population to contain precessing binaries 1 , 2 . Imprints of precession have been investigated in several signals 3 – 5 , but no definitive identification of orbital precession has been reported in any of the 84 BBH observations so far 5 – 7 by the Advanced LIGO and Virgo detectors 8 , 9 . Here we report the measurement of strong-field precession in the LIGO–Virgo–Kagra gravitational-wave signal GW200129. The binary’s orbit precesses at a rate ten orders of magnitude faster than previous weak-field measurements from binary pulsars 10 – 13 . We also find that the primary black hole is probably highly spinning. According to current binary population estimates, a GW200129-like signal is extremely unlikely, and therefore presents a direct challenge to many current binary-formation models.  Analysis of a gravitational-wave signal reveals a strongly precessing black-hole binary that contains a rapidly spinning black hole.

Two-level systems are at the core of numerous real-world technologies such as magnetic resonance imaging and atomic clocks. Coherent control of the state is achieved with an oscillating field that drives dynamics at a rate determined by its amplitude. As the strength of the field is increased, a different regime emerges where linear scaling of the manipulation rate breaks down and complex dynamics are expected. By calibrating the spin rotation with an adiabatic passage, we have measured the room-temperature \"strong-driving\" dynamics of a single nitrogen vacancy center in diamond. With an adiabatic passage to calibrate the spin rotation, we observed dynamics on sub-nanosecond time scales. Contrary to conventional thinking, this breakdown of the rotating wave approximation provides opportunities for time-optimal quantum control of a single spin.