Courtship and Copulation in Glaucous-Winged Gulls, Larus Glaucescens

Using video recordings and scan counts, I examined the occurrence, sequences, and durations of behavior and environmental factors associated with courtship and copulation in glaucous-winged gulls, Larus glaucescens. Males and females in a pair had equivalent pre- and post-Mount behavior occurrences and durations. The main courtship sequence was Head Toss -- Courtship Beg/Respond -- Mounted/Mount, and felames appeared to initiate transitions between these pre-Mount behaviors. More Mounts occurred during the egg-laying stage of the breeding season, but copulation duration, wing-flag duration, and cloacal contacts per copulation showed no significant differences across sampling periods. Poisson analysis showed no significant grouping of Mounts in time during the days sampled. Bald eagle (Haliaeetus leucocephalus) disturbance was correlated with increased courtship and copulation frequency. Other environmental factors affecting courtship and copulation included day of year, tide height, and solar elevation. Peak Mounts and Courtship Begs per territory occurred two days before the Courtship Feeds and 10 days before peack clutch initiations

Observing mergers of non-spinning black-hole binaries

Advances in the field of numerical relativity now make it possible to calculate the final, most powerful merger phase of binary black-hole coalescence for generic binaries. The state of the art has advanced well beyond the equal-mass case into the unequal-mass and spinning regions of parameter space. We present a study of the nonspinning portion of parameter space, primarily using an analytic waveform model tuned to available numerical data, with an emphasis on observational implications. We investigate the impact of varied mass ratio on merger signal-to-noise ratios (SNRs) for several detectors, and compare our results with expectations from the test-mass limit. We note a striking similarity of the waveform phasing of the merger waveform across the available mass ratios. Motivated by this, we calculate the match between our 1:1 (equal mass) and 4:1 mass-ratio waveforms during the merger as a function of location on the source sky, using a new formalism for the match that accounts for higher harmonics. This is an indicator of the amount of degeneracy in mass ratio for mergers of moderate-mass-ratio systems.Comment: 13 pages, 11 figures, submitted to Phys. Rev.

Modeling kicks from the merger of generic black-hole binaries

Recent numerical relativistic results demonstrate that the merger of comparable-mass spinning black holes has a maximum ``recoil kick'' of up to \sim 4000 \kms. However the scaling of these recoil velocities with mass ratio is poorly understood. We present new runs showing that the maximum possible kick perpendicular to the orbital plane does not scale as $\sim\eta^2$ (where $\eta$ is the symmetric mass ratio), as previously proposed, but is more consistent with $\sim\eta^3$, at least for systems with low orbital precession. We discuss the effect of this dependence on galactic ejection scenarios and retention of intermediate-mass black holes in globular clusters.Comment: 5 pages, 1 figure, 3 tables. Version published in Astrophys. J. Let

Gravitational Radiation Characteristics of Nonspinning Black-Hole Binaries

We present a detailed descriptive analysis of the gravitational radiation from binary mergers of non-spinning black holes, based on numerical relativity simulations of systems varying from equal-mass to a 6:1 mass ratio. Our analysis covers amplitude and phase characteristics of the radiation, suggesting a unified picture of the waveforms' dominant features in terms of an implicit rotating source, applying uniformly to the full wavetrain, from inspiral through ringdown. We construct a model of the late-stage frequency evolution that fits the l = m modes, and identify late-time relationships between waveform frequency and amplitude. These relationships allow us to construct a predictive model for the late-time waveforms, an alternative to the common practice of modelling by a sum of quasinormal mode overtones. We demonstrate an application of this in a new effective-one-body-based analytic waveform model

Binary black hole merger in the extreme mass ratio limit

We discuss the transition from quasi-circular inspiral to plunge of a system of two nonrotating black holes of masses $m_1$ and $m_2$ in the extreme mass ratio limit $m_1m_2\ll (m_1+m_2)^2$. In the spirit of the Effective One Body (EOB) approach to the general relativistic dynamics of binary systems, the dynamics of the two black hole system is represented in terms of an effective particle of mass $\mu\equiv m_1m_2/(m_1+m_2)$ moving in a (quasi-)Schwarzschild background of mass $M\equiv m_1+m_2$ and submitted to an ${\cal O}(\mu)$ radiation reaction force defined by Pad\'e resumming high-order Post-Newtonian results. We then complete this approach by numerically computing, \`a la Regge-Wheeler-Zerilli, the gravitational radiation emitted by such a particle. Several tests of the numerical procedure are presented. We focus on gravitational waveforms and the related energy and angular momentum losses. We view this work as a contribution to the matching between analytical and numerical methods within an EOB-type framework.Comment: 14 pages, six figures. Revised version. To appear in the CQG special issue based around New Frontiers in Numerical Relativity conference, Golm (Germany), July 17-21 200

Modeling kicks from the merger of generic black-hole binaries

Recent numerical relativistic results demonstrate that the merger of comparable-mass spinning black holes has a maximum ``recoil kick'' of up to \sim 4000 \kms. However the scaling of these recoil velocities with mass ratio is poorly understood. We present new runs showing that the maximum possible kick perpendicular to the orbital plane does not scale as $\sim\eta^2$ (where $\eta$ is the symmetric mass ratio), as previously proposed, but is more consistent with $\sim\eta^3$, at least for systems with low orbital precession. We discuss the effect of this dependence on galactic ejection scenarios and retention of intermediate-mass black holes in globular clusters.Comment: 5 pages, 1 figure, 3 tables. Version published in Astrophys. J. Let

Pseudotemporal invitations: 6- to 9-year-old maltreated children’s tendency to misinterpret invitations referencing “time” as solely requesting conventional temporal information

Forensic interviewers ask children broad input-free recall questions about individual episodes in order to elicit complete narratives, often asking about “the first time,” “the last time,” and “one time.” An overlooked problem is that the word “time” is potentially ambiguous, referring both to a particular episode and to conventional temporal information. We examined 191 6-9-year-old maltreated children’s responses to questions about recent events varying the wording of the invitations, either asking children to “tell me about” or “tell me what happened” one time/the first time/the last time the child experienced recent recurrent events. Additionally, half of the children were asked a series of “when” questions about recurrent events before the invitations. Children were several times more likely to provide exclusively conventional temporal information to “tell me about” invitations compared to “tell me what happened” invitations, and asking “when” questions before the invitations increased children’s tendency to give exclusively conventional temporal information. Children who answered a higher proportion of “when” questions with conventional temporal information were also more likely to do so in response to the invitations. The results suggest that children may often fail to provide narrative information because they misinterpret invitations using the word “time.