Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect

PubMed Central

Lu, Xiancong; Wu, Ziwen; Zhang, Wuhong; Chen, Lixiang

2014-01-01

The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved. PMID:24784778

Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect.

PubMed

Lu, Xiancong; Wu, Ziwen; Zhang, Wuhong; Chen, Lixiang

2014-05-02

The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved.

Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect

NASA Astrophysics Data System (ADS)

Lu, Xiancong; Wu, Ziwen; Zhang, Wuhong; Chen, Lixiang

2014-05-01

The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved.

Illustrating chaos: a schematic discretization of the general three-body problem in Newtonian gravity

NASA Astrophysics Data System (ADS)

Leigh, Nathan W. C.; Wegsman, Shalma

2018-05-01

We present a formalism for constructing schematic diagrams to depict chaotic three-body interactions in Newtonian gravity. This is done by decomposing each interaction into a series of discrete transformations in energy- and angular momentum-space. Each time a transformation is applied, the system changes state as the particles re-distribute their energy and angular momenta. These diagrams have the virtue of containing all of the quantitative information needed to fully characterize most bound or unbound interactions through time and space, including the total duration of the interaction, the initial and final stable states in addition to every intervening temporary meta-stable state. As shown via an illustrative example for the bound case, prolonged excursions of one of the particles, which by far dominates the computational cost of the simulations, are reduced to a single discrete transformation in energy- and angular momentum-space, thereby potentially mitigating any computational expense. We further generalize our formalism to sequences of (unbound) three-body interactions, as occur in dense stellar environments during binary hardening. Finally, we provide a method for dynamically evolving entire populations of binaries via three-body scattering interactions, using a purely analytic formalism. In principle, the techniques presented here are adaptable to other three-body problems that conserve energy and angular momentum.

Orbital-plane precessional resonances for binary black-hole systems

NASA Astrophysics Data System (ADS)

Kesden, Michael; Zhao, Xinyu; Gerosa, Davide

2016-03-01

We derive a new class of post-Newtonian precessional resonances for binary black holes (BBHs) with misaligned spins. According to the orbit-averaged spin-precession equations, the angle between the orbital angular momentum L and the total angular momentum J oscillates with a period τ during which time L precesses about J by an angle α. If α is a rational multiple of 2 π, the precession of L will be closed indicating a resonance between the polar and azimuthal evolution of L . If α is an integer multiple of 2 π, the misalignment between the angular momentum ΔL radiated over the period τ and J will be minimized, as will the opening angle of the cone about which J precesses in an inertial frame. However, the direction of ΔL will remain nearly fixed in an inertial frame over many precessional periods, causing the direction of J to tilt as inspiraling BBHs pass through such a resonance. Generic BBHs encounter many such resonances during an inspiral from large separations. We derive the evolution of J near a resonance and assess their detectability by gravitational-wave detectors and astrophysical implications.

Black-hole binaries as relics of gamma-ray burst/hypernova explosions

NASA Astrophysics Data System (ADS)

Moreno Mendez, Enrique

The Collapsar model, in which a fast-spinning massive star collapses into a Kerr black hole, has become the standard model to explain long-soft gamma-ray bursts and hypernova explosions (GRB/HN). However, stars massive enough (those with ZAMS mass ≳ (18--20) M⊙ ) to produce these events evolve through a path that loses too much angular momentum to produce a central engine capable of delivering the necessary energy. In this work I suggest that the soft X-ray transient sources are the remnants of GRBs/HNe. Binaries in which the massive primary star evolves a carbon-oxygen burning core, then start to transfer material to the secondary star (Case C mass transfer), causing the orbit to decay until a common-envelope phase sets in. The secondary spirals in, further narrowing the orbit of the binary and removing the hydrogen envelope of the primary star. Eventually the primary star becomes tidally locked and spins up, acquiring enough rotational energy to power up a GRB/HN explosion. The central engine producing the GRB/HN event is the Kerr black hole acting through the Blandford-Znajek mechanism. This model can explain not only the long-soft GRBs, but also the subluminous bursts (which comprise ˜ 97% of the total), the long-soft bursts and the short-hard bursts (in a neutron star, black hole merger). Because of our binary evolution through Case C mass transfer, it turns out that for the subluminous and cosmological bursts, the angular momentum O is proportional to m3/2D , where mD is the mass of the donor (secondary star). This binary evolution model has a great advantage over the Woosley Collapsar model; one can "dial" the donor mass in order to obtain whatever angular momentum is needed to drive the explosion. Population syntheses show that there are enough binaries to account for the progenitors of all known classes of GRBs.

On the Peculiarities of Evolutionary History of EHB Objects in Binary Systems with Hot Subdwarf Companions

NASA Astrophysics Data System (ADS)

Pustynski, V.-V.; Pustylnik, I.

2006-03-01

It has been shown quite recently (Maxted etal 2001, Morales-Rueda etal 2003) that dB stars, extreme horizontal branch (EHB) objects, likely all belong to binary systems. We study in detail the mass and angular momentum loss in the giant progenitors of sdB stars in an attempt to clarify why binarity must be a crucial factor in producing EHB objects. Assuming that the progenitors of EHB objects belong to the binaries with initial separations of 100-150 R_odot and fill in their critical Roche lobes while being close to the RGB tip we have found that considerable shrinkage of the orbit can be achieved due to the combined effect of angular momentum loss from the red giant and appreciable accretion on its low mass companion on the hydrodynamical time scale of the donor resulting in formation of helium white dwarfs with masses about 0.5 M_odot and thus evading the common envelope stage.

Primary Surface Particle Motion as a Mechanism for YORP-Driven Binary Asteroid Evolution

NASA Astrophysics Data System (ADS)

Fahnestock, Eugene G.; Scheeres, D. J.

2008-09-01

Within the largest class of binary asteroid systems -- asynchronous binaries typified by 1999 KW4 -- we hypothesize continued YORP spin-up of the rapidly rotating primary leads to recurring episodic lofting motion of primary equator regolith. We theorize this is a mechanism for transporting YORP-injected angular momentum from primary spin into the mutual orbit. This both enables binary primaries to continue to spin at near surface fission rates and produces continued orbit expansion on time scales several times faster than expansion predicted by tidal dissipation alone. This is distinct from the Binary Yorp (BYORP) phenomenon, not studied in this work but to be added to it later. We evaluate our hypotheses using a combination of techniques for an example binary system. First high-fidelity dynamic simulation of surface-originating particles in the full-detail gravity field of the binary components, themselves propagated according to the full two body problem, gives particle final disposition (return impact, transfer impact, escape). Trajectory end states found for regolith lofted at different initial primary spin rates and relative poses are collected into probability matrices, allowing probabilistic propagation of surface particles for long durations at low computational cost. We track changes to mass, inertia dyad, rotation state, and centroid position and velocity for each component in response to this mapped particle motion. This allows tracking of primary, secondary, and mutual orbit angular momenta over time, clearly demonstrating the angular momentum transfer mechanism and validating our hypotheses. We present current orbit expansion rates and estimated orbit size doubling times consistent with this mechanism, for a few binary systems. We also discuss ramifications of this type of rapid binary evolution towards separation, including the frequency with which "divorced binaries" on similar heliocentric orbits are produced, formation of triple systems such as 2001 SN263, and separation timescale dependence on heliocentric distance.

Experimental quantum cryptography with qutrits

NASA Astrophysics Data System (ADS)

Gröblacher, Simon; Jennewein, Thomas; Vaziri, Alipasha; Weihs, Gregor; Zeilinger, Anton

2006-05-01

We produce two identical keys using, for the first time, entangled trinary quantum systems (qutrits) for quantum key distribution. The advantage of qutrits over the normally used binary quantum systems is an increased coding density and a higher security margin. The qutrits are encoded into the orbital angular momentum of photons, namely Laguerre Gaussian modes with azimuthal index l + 1, 0 and -1, respectively. The orbital angular momentum is controlled with phase holograms. In an Ekert-type protocol the violation of a three-dimensional Bell inequality verifies the security of the generated keys. A key is obtained with a qutrit error rate of approximately 10%.

Three-dimensional Hydrodynamical Simulations of Mass Transfer in Binary Systems by a Free Wind

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Zheng-Wei; Stancliffe, Richard J.; Abate, Carlo

A large fraction of stars in binary systems are expected to undergo mass and angular momentum exchange at some point in their evolution, which can drastically alter the chemical and dynamical properties and fates of the systems. Interaction by stellar wind is an important process in wide binaries. However, the details of wind mass transfer are still not well understood. We perform three-dimensional hydrodynamical simulations of wind mass transfer in binary systems to explore mass-accretion efficiencies and geometries of mass outflows, for a range of mass ratios from 0.05 to 1.0. In particular, we focus on the case of amore » free wind, in which some physical mechanism accelerates the expelled wind material balancing the gravity of the mass-losing star with the wind velocity comparable to the orbital velocity of the system. We find that the mass-accretion efficiency and accreted specific angular momentum increase with the mass ratio of the system. For an adiabatic wind, we obtain that the accretion efficiency onto the secondary star varies from about 0.1% to 8% for mass ratios between 0.05 and 1.0.« less

Reduced modeling of the magnetorotational instability

NASA Astrophysics Data System (ADS)

Jamroz, Ben F.

2009-06-01

Accretion describes the process by which matter in an astrophysical disk falls onto a central massive object. Accretion disks are present in many astrophysical situations including binary star systems, young stellar objects, and near black holes at the center of galaxies. Measurements from observations of these disks have shown that viscous processes are unable to transport the necessary levels of angular momentum needed for accretion. Therefore, accretion requires an efficient mechanism of angular momentum transport. Mixing by turbulent processes greatly enhances the level of angular momentum transport in a turbulent fluid. Thus, the generation of turbulence in these disks may provide the mechanism needed for accretion. A classical result of hydrodynamic theory is that typical accretion disks are hydrodynamically stable to shear instabilities, since the specific angular momentum increases outwards. Other processes of generating hydrodynamic turbulence (barotropic instability, baroclinic instability, sound wave, shock waves, finite amplitude instabilities) may be present in these disks, however, none of these mechanisms has been shown to produce the level of angular momentum transport needed for accretion. Hydrodynamical turbulence does not produce enough angular momentum transport to produce the level of accretion observed in astrophysical accretion disks. The leading candidate for the source of turbulence leading to the transport of angular momentum is the magnetorotational instability, a linear axisymmetric instability of electrically conducting fluid in the presence of an imposed magnetic field and shear (or differential rotation). This instability is an efficient mechanism of angular momentum transport generating the level of transport needed for accretion. The level of effective angular momentum transport is determined by the saturated state of sustained turbulence generated by the instability. The mechanism of nonlinear saturation of this instability is not well understood. Many recent numerical investigations of this problem are performed in a local domain, where the global cylindrical background state is projected onto a local Cartesian domain. The resulting system is then numerically modeled within a "shearing box" framework to obtain estimates of angular momentum transport and therefore accretion. However, the simplified geometry of the local domain, and the projection of global quantities leads to a model where the instability is able to grow unboundedly. Utilizing disparate characteristic scales, this thesis presents a reduced asymptotic model for the magnetorotational instability that allows a large scale feedback of local stresses (Reynolds, Maxwell and mixed) onto the projected background state. This system is investigated numerically to determine the impact of allowing this feedback on the saturated level of angular momentum transport.

The influence of massive black hole binaries on the morphology of merger remnants

NASA Astrophysics Data System (ADS)

Bortolas, E.; Gualandris, A.; Dotti, M.; Read, J. I.

2018-06-01

Massive black hole (MBH) binaries, formed as a result of galaxy mergers, are expected to harden by dynamical friction and three-body stellar scatterings, until emission of gravitational waves (GWs) leads to their final coalescence. According to recent simulations, MBH binaries can efficiently harden via stellar encounters only when the host geometry is triaxial, even if only modestly, as angular momentum diffusion allows an efficient repopulation of the binary loss cone. In this paper, we carry out a suite of N-body simulations of equal-mass galaxy collisions, varying the initial orbits and density profiles for the merging galaxies and running simulations both with and without central MBHs. We find that the presence of an MBH binary in the remnant makes the system nearly oblate, aligned with the galaxy merger plane, within a radius enclosing 100 MBH masses. We never find binary hosts to be prolate on any scale. The decaying MBHs slightly enhance the tangential anisotropy in the centre of the remnant due to angular momentum injection and the slingshot ejection of stars on nearly radial orbits. This latter effect results in about 1 per cent of the remnant stars being expelled from the galactic nucleus. Finally, we do not find any strong connection between the remnant morphology and the binary hardening rate, which depends only on the inner density slope of the remnant galaxy. Our results suggest that MBH binaries are able to coalesce within a few Gyr, even if the binary is found to partially erase the merger-induced triaxiality from the remnant.

Supranova Events from Spun-up Neutron Stars: An Explosion in Search of an Observation

NASA Astrophysics Data System (ADS)

Vietri, Mario; Stella, Luigi

1999-12-01

We consider a formation scenario for supramassive neutron stars (SMNSs) that takes place through mass and angular momentum transfer from a close companion during a low-mass X-ray binary phase, with the ensuing suppression of the magnetic field. After the end of the mass transfer phase, SMNSs will lose, through magnetic dipole radiation, most of their angular momentum, triggering the star's collapse to a black hole. We discuss the rate of occurrence of these collapses and propose that these stars, because of the baryon-clear environment in which the implosion/explosion takes place, are the originators of gamma-ray bursts.

On the Lack of Circumbinary Planets Orbiting Isolated Binary Stars

NASA Astrophysics Data System (ADS)

Fleming, David P.; Barnes, Rory; Graham, David E.; Luger, Rodrigo; Quinn, Thomas R.

2018-05-01

We outline a mechanism that explains the observed lack of circumbinary planets (CBPs) via coupled stellar–tidal evolution of isolated binary stars. Tidal forces between low-mass, short-period binary stars on the pre-main sequence slow the stellar rotations transferring rotational angular momentum to the orbit as the stars approach the tidally locked state. This transfer increases the binary orbital period, expanding the region of dynamical instability around the binary, and destabilizing CBPs that tend to preferentially orbit just beyond the initial dynamical stability limit. After the stars tidally lock, we find that angular momentum loss due to magnetic braking can significantly shrink the binary orbit, and hence the region of dynamical stability, over time, impacting where surviving CBPs are observed relative to the boundary. We perform simulations over a wide range of parameter space and find that the expansion of the instability region occurs for most plausible initial conditions and that, in some cases, the stability semimajor axis doubles from its initial value. We examine the dynamical and observable consequences of a CBP falling within the dynamical instability limit by running N-body simulations of circumbinary planetary systems and find that, typically, at least one planet is ejected from the system. We apply our theory to the shortest-period Kepler binary that possesses a CBP, Kepler-47, and find that its existence is consistent with our model. Under conservative assumptions, we find that coupled stellar–tidal evolution of pre-main sequence binary stars removes at least one close-in CBP in 87% of multi-planet circumbinary systems.

mocca-SURVEY database I. Accreting white dwarf binary systems in globular clusters - III. Cataclysmic variables - implications of model assumptions

NASA Astrophysics Data System (ADS)

Belloni, Diogo; Zorotovic, Mónica; Schreiber, Matthias R.; Leigh, Nathan W. C.; Giersz, Mirek; Askar, Abbas

2017-06-01

In this third of a series of papers related to cataclysmic variables (CVs) and related objects, we analyse the population of CVs in a set of 12 globular cluster models evolved with the MOCCA Monte Carlo code, for two initial binary populations (IBPs), two choices of common-envelope phase (CEP) parameters, and three different models for the evolution of CVs and the treatment of angular momentum loss. When more realistic models and parameters are considered, we find that present-day cluster CV duty cycles are extremely low (≲0.1 per cent) that makes their detection during outbursts rather difficult. Additionally, the IBP plays a significant role in shaping the CV population properties, and models that follow the Kroupa IBP are less affected by enhanced angular momentum loss. We also predict from our simulations that CVs formed dynamically in the past few Gyr (massive CVs) correspond to bright CVs (as expected) and that faint CVs formed several Gyr ago (dynamically or not) represent the overwhelming majority. Regarding the CV formation rate, we rule out the notion that it is similar irrespective of the cluster properties. Finally, we discuss the differences in the present-day CV properties related to the IBPs, the initial cluster conditions, the CEP parameters, formation channels, the CV evolution models and the angular momentum loss treatments.

Detecting binary neutron star systems with spin in advanced gravitational-wave detectors

NASA Astrophysics Data System (ADS)

Brown, Duncan A.; Harry, Ian; Lundgren, Andrew; Nitz, Alexander H.

2012-10-01

The detection of gravitational waves from binary neutron stars is a major goal of the gravitational-wave observatories Advanced LIGO and Advanced Virgo. Previous searches for binary neutron stars with LIGO and Virgo neglected the component stars’ angular momentum (spin). We demonstrate that neglecting spin in matched-filter searches causes advanced detectors to lose more than 3% of the possible signal-to-noise ratio for 59% (6%) of sources, assuming that neutron star dimensionless spins, cJ/GM2, are uniformly distributed with magnitudes between 0 and 0.4 (0.05) and that the neutron stars have isotropically distributed spin orientations. We present a new method for constructing template banks for gravitational-wave searches for systems with spin. We present a new metric in a parameter space in which the template placement metric is globally flat. This new method can create template banks of signals with nonzero spins that are (anti-)aligned with the orbital angular momentum. We show that this search loses more than 3% of the maximum signal-to-noise for only 9% (0.2%) of binary neutron star sources with dimensionless spins between 0 and 0.4 (0.05) and isotropic spin orientations. Use of this template bank will prevent selection bias in gravitational-wave searches and allow a more accurate exploration of the distribution of spins in binary neutron stars.

Plan-B - Do All Planetary Nebulae Derive From Binaries?

NASA Astrophysics Data System (ADS)

De Marco, Orsola; PLAN-B working Group

2007-12-01

The planetary nebula (PN) field is facing a paradigm problem. For the last thirty years the role of binarity in the formation and shaping of PNe has been hotly debated. The majority of the active research community favored a scenario in which the majority of PNe are formed by single asymptotic giant stars that impart elliptical and bipolar shapes to their ejected envelopes by means of rotation and magnetic fields. However it has recently come to light that magnetic fields and rotation would not survive in a single star for long enough to be dynamically important. What is needed is an angular momentum source which can resupply the star of rotation at the right time. This angular momentum reservoir is most likely in the form of a binary companion. Today we know of only a handful of binary central stars of PN which are close enough to have interacted. Detecting binary central stars has therefore become paramount to provide an observational confirmation of the binary hypothesis. This task has however proven to be difficult, since most of the traditional techniques are difficult to apply to these bright, windy, and pulsating stars. In June 2007 an international working group has therefore been forged to aggressively tackle this observational challenge with a diverse range of observational approaches. This This work is funded in part by NSF grant AST-0607111 (PI: De Marco)

Precessional Instability in Binary Black Holes with Aligned Spins.

PubMed

Gerosa, Davide; Kesden, Michael; O'Shaughnessy, Richard; Klein, Antoine; Berti, Emanuele; Sperhake, Ulrich; Trifirò, Daniele

2015-10-02

Binary black holes on quasicircular orbits with spins aligned with their orbital angular momentum have been test beds for analytic and numerical relativity for decades, not least because symmetry ensures that such configurations are equilibrium solutions to the spin-precession equations. In this work, we show that these solutions can be unstable when the spin of the higher-mass black hole is aligned with the orbital angular momentum and the spin of the lower-mass black hole is antialigned. Spins in these configurations are unstable to precession to large misalignment when the binary separation r is between the values r(ud±)=(√(χ(1))±√(qχ(2)))(4)(1-q)(-2)M, where M is the total mass, q≡m(2)/m(1) is the mass ratio, and χ(1) (χ(2)) is the dimensionless spin of the more (less) massive black hole. This instability exists for a wide range of spin magnitudes and mass ratios and can occur in the strong-field regime near the merger. We describe the origin and nature of the instability using recently developed analytical techniques to characterize fully generic spin precession. This instability provides a channel to circumvent astrophysical spin alignment at large binary separations, allowing significant spin precession prior to merger affecting both gravitational-wave and electromagnetic signatures of stellar-mass and supermassive binary black holes.

Testing tidal theory for evolved stars by using red-giant binaries observed by Kepler

NASA Astrophysics Data System (ADS)

Beck, P. G.; Mathis, S.; Gallet, F.; Charbonnel, C.; Benbakoura, M.; García, R. A.; do Nascimento, J.-D.

2018-06-01

Tidal interaction governs the redistribution of angular momentum in close binary stars and planetary systems and determines the systems evolution towards the possible equilibrium state. Turbulent friction acting on the equilibrium tide in the convective envelope of low-mass stars is known to have a strong impact on this exchange of angular momentum in binaries. Moreover, theoretical modelling in recent literature as well as presented in this paper suggests that the dissipation of the dynamical tide, constituted of tidal inertial waves propagating in the convective envelope, is weak compared to the dissipation of the equilibrium tide during the red-giant phase. This prediction is confirmed when we apply the equilibrium-tide formalism developed by Zahn (1977), Verbunt & Phinney (1995), and Remus, Mathis & Zahn (2012) onto the sample of all known red-giant binaries observed by the NASA Kepler mission. Moreover, the observations are adequately explained by only invoking the equilibrium tide dissipation. Such ensemble analysis also benefits from the seismic characterisation of the oscillating components and surface rotation rates. Through asteroseismology, previous claims of the eccentricity as an evolutionary state diagnostic are discarded. This result is important for our understanding of the evolution of multiple star and planetary systems during advanced stages of stellar evolution.

Planet Formation in Disks with Inclined Binary Companions: Can Primordial Spin-Orbit Misalignment be Produced?

NASA Astrophysics Data System (ADS)

Zanazzi, J. J.; Lai, Dong

2018-04-01

Many hot Jupiter (HJ) systems have been observed to have their stellar spin axis misaligned with the planet's orbital angular momentum axis. The origin of this spin-orbit misalignment and the formation mechanism of HJs remain poorly understood. A number of recent works have suggested that gravitational interactions between host stars, protoplanetary disks, and inclined binary companions may tilt the stellar spin axis with respect to the disk's angular angular momentum axis, producing planetary systems with misaligned orbits. These previous works considered idealized disk evolution models and neglected the gravitational influence of newly formed planets. In this paper, we explore how disk photoevaporation and planet formation and migration affect the inclination evolution of planet-star-disk-binary systems. We take into account planet-disk interactions and the gravitational spin-orbit coupling between the host star and the planet. We find that the rapid depletion of the inner disk via photoevaporation reduces the excitation of stellar obliquities. Depending on the formation and migration history of HJs, the spin-orbit coupling between the star and the planet may reduces and even completely suppress the excitation of stellar obliquities. Our work constrains the formation/migration history of HJs. On the other hand, planetary systems with "cold" Jupiters or close-in super-earths may experience excitation of stellar obliquities in the presence of distant inclined companions.

Planet formation in discs with inclined binary companions: can primordial spin-orbit misalignment be produced?

NASA Astrophysics Data System (ADS)

Zanazzi, J. J.; Lai, Dong

2018-07-01

Many hot Jupiter (HJ) systems have been observed to have their stellar spin axis misaligned with the planet's orbital angular momentum axis. The origin of this spin-orbit misalignment and the formation mechanism of HJs remain poorly understood. A number of recent works have suggested that gravitational interactions between host stars, protoplanetary discs, and inclined binary companions may tilt the stellar spin axis with respect to the disc's angular angular momentum axis, producing planetary systems with misaligned orbits. These previous works considered idealized disc evolution models and neglected the gravitational influence of newly formed planets. In this paper, we explore how disc photoevaporation and planet formation and migration affect the inclination evolution of planet-star-disc-binary systems. We take into account planet-disc interactions and the gravitational spin-orbit coupling between the host star and the planet. We find that the rapid depletion of the inner disc via photoevaporation reduces the excitation of stellar obliquities. Depending on the formation and migration history of HJs, the spin-orbit coupling between the star and the planet may reduces and even completely suppress the excitation of stellar obliquities. Our work constrains the formation/migration history of HJs. On the other hand, planetary systems with `cold' Jupiters or close-in super-earths may experience excitation of stellar obliquities in the presence of distant inclined companions.

Irradiation and Enhanced Magnetic Braking in Cataclysmic Variables

NASA Astrophysics Data System (ADS)

McCormick, P. J.; Frank, J.

1998-12-01

In previous work we have shown that irradiation driven mass transfer cycles can occur in cataclysmic variables at all orbital periods if an additional angular momentum loss mechanism is assumed. Earlier models simply postulated that the enhanced angular momentum loss was proportional to the mass transfer rate without any specific physical model. In this paper we present a simple modification of magnetic braking which seems to have the right properties to sustain irradiation driven cycles at all orbital periods. We assume that the wind mass loss from the irradiated companion consists of two parts: an intrinsic stellar wind term plus an enhancement that is proportional to the irradiation. The increase in mass flow reduces the specific angular momentum carried away by the flow but nevertheless yields an enhanced rate of magnetic braking. The secular evolution of the binary is then computed numerically with a suitably modified double polytropic code (McCormick & Frank 1998). With the above model and under certain conditions, mass transfer oscillations occur at all orbital periods.

Research on the Orbital Period of Massive Binaries

NASA Astrophysics Data System (ADS)

Zhao, E.; Qain, S.

2011-12-01

Massive binary is the kind of binary, whose spectral type is earlier than B5. Research on massive binary plays an important role in the mass and angular momentum transfer or loss between the components, and the evolution of binary. Some massive binaries are observed and analyzed, including O-type binary LY Aur, B-type contact binary RZ Pyx and B-type semi-detached binary AI Cru. It is found that all of their periods have a long-term increasing, which indicates that the system is undergoing a Case A slow mass transfer stage on the nuclear time-scale of the secondary. Moreover, analysis show a cyclic change of orbital period, which can be explained by the light-travel effect time of the third body.

The puzzling orbital period evolution of the LMXB AX J1745.6-2901

NASA Astrophysics Data System (ADS)

Ponti, G.; De, K.; Munoz-Darias, T.; Stella, L.; Nandra, K.

2017-10-01

The discovery of gravitational waves through mergers of binary black holes raises the question of how such compact systems form, renewing issues related to the orbital evolution of binary systems. Eclipsing X-ray binaries are excellent tools to constrain the orbital period evolution and how the system loses angular momentum. I will present an X-ray eclipse timing analysis (spanning an interval of more than 20 yr) of one of such objects, AX J1745.6-2901. Its orbital period is decreasing at a rate Pdotorb=-4.03+-0.32 e-11 s s-1, at least one order of magnitude larger than expected from conservative mass transfer and angular momentum losses due to gravitational waves and magnetic braking, and it might result from either non-conservative mass transfer or magnetic activity changing the quadrupole moment of the companion star. I will also show that imprinted on the long-term evolution of the orbit, there are highly significant eclipse leads delays of 10-30 s, characterized by a clear state dependence in which, on average, eclipses occur earlier during the hard state. Finally, I will discuss whether accretion disc winds might have an impact onto the orbital evolution.

LDPC-coded orbital angular momentum (OAM) modulation for free-space optical communication.

PubMed

Djordjevic, Ivan B; Arabaci, Murat

2010-11-22

An orbital angular momentum (OAM) based LDPC-coded modulation scheme suitable for use in FSO communication is proposed. We demonstrate that the proposed scheme can operate under strong atmospheric turbulence regime and enable 100 Gb/s optical transmission while employing 10 Gb/s components. Both binary and nonbinary LDPC-coded OAM modulations are studied. In addition to providing better BER performance, the nonbinary LDPC-coded modulation reduces overall decoder complexity and latency. The nonbinary LDPC-coded OAM modulation provides a net coding gain of 9.3 dB at the BER of 10(-8). The maximum-ratio combining scheme outperforms the corresponding equal-gain combining scheme by almost 2.5 dB.

A new photometric study of the triple star system EF Draconis

NASA Astrophysics Data System (ADS)

Yang, Yuan-Gui

2012-04-01

We present new charge-coupled device (CCD) photometry for the triple star EF Draconis, obtained in 2009 and 2011. Using the updated Wilson-Devinney program, the photometric solutions were deduced from two sets of light curves. The results indicate that EF Dra is an A-type W UMa binary with a contact degree of f = 46.7%(±0.6%) and a third light of l3 ≃ 1.5%. Through analyzing the O — C curve, it is found that the orbital period shows a long-time increase with a light-time orbit. The period, semi-amplitude and eccentricity of the third body are Pmod = 17.20(±0.18) yr, A = 0.0039d(±0.0002d) and e = 0.49(±0.02) respectively. This kind of tertiary companion may extract angular momentum from the central system. The orbital period of EF Dra secularly increases at a rate of dP/dt = +3.72(±0.07) × 10-7 d yr-1, which may be interpreted by mass transfer from the less massive to the more massive component. As period increases, the separation between components may increase, which will cause the contact degree to decrease. With mass transferring, the spin angular momentum will increase, while the orbital angular momentum will decrease. Only if the contact configuration would merge at could this kind of deep-contact binary with period increasing, such as EF Dra, evolve into a rapidly-rotating single star.

Distinguishing black-hole spin-orbit resonances by their gravitational-wave signatures

NASA Astrophysics Data System (ADS)

Gerosa, Davide; O'Shaughnessy, Richard; Kesden, Michael; Berti, Emanuele; Sperhake, Ulrich

2014-06-01

If binary black holes form following the successive core collapses of sufficiently massive binary stars, precessional dynamics may align their spins, Smathvariant="bold">1 and Smathvariant="bold">2, and the orbital angular momentum L into a plane in which they jointly precess about the total angular momentum J. These spin orientations are known as spin-orbit resonances since S1, S2, and L all precess at the same frequency to maintain their planar configuration. Two families of such spin-orbit resonances exist, differentiated by whether the components of the two spins in the orbital plane are either aligned or antialigned. The fraction of binary black holes in each family is determined by the stellar evolution of their progenitors, so if gravitational-wave detectors could measure this fraction they could provide important insights into astrophysical formation scenarios for binary black holes. In this paper, we show that even under the conservative assumption that binary black holes are observed along the direction of J (where precession-induced modulations to the gravitational waveforms are minimized), the waveforms of many members of each resonant family can be distinguished from all members of the other family in events with signal-to-noise ratios ρ ≃10, typical of those expected for the first detections with Advanced LIGO and Virgo. We hope that our preliminary findings inspire a greater appreciation of the capability of gravitational-wave detectors to constrain stellar astrophysics and stimulate further studies of the distinguishability of spin-orbit resonant families in more expanded regions of binary black-hole parameter space.

Multiple color light curves and period changes investigation of the contact binary HV Aqr

NASA Astrophysics Data System (ADS)

Li, K.; Qian, S.-B.

2013-07-01

New V, R and I light curves of the short period binary system, HV Aqr, are presented. Photometric solutions were derived using the Wilson-Devinney code. Our new determined light curves do not show O'Connell effect. The nearly symmetry and complete eclipses of the light curves of HV Aqr enable us to determine high-precision photometric parameters of the binary system. The new solutions suggest that HV Aqr is a low mass ratio (q=0.1455) deep contact binary with a contact degree of f=55.9%. Based on all available times of light minimum, we analyzed the long-term period changes of HV Aqr. A secular decrease rate of dP/dt=8.84(±0.18)×10-8 days yr-1 was determined. The continuous period decrease can be explained by the mass transfer from the primary component to the secondary and angular momentum loss via magnetic stellar wind. A conservative mass transfer rate of dM1/dt=1.81×10-8M⊙ yr-1 and angular momentum loss rate at dJ/dt=5.96×1045 g cm2 s-1 yr-1 were derived. As the orbital period decreases, the contact degree of HV Aqr will become deeper and finally it will evolve into a single rapid-rotation star.

Demonstration of free space coherent optical communication using integrated silicon photonic orbital angular momentum devices.

PubMed

Su, Tiehui; Scott, Ryan P; Djordjevic, Stevan S; Fontaine, Nicolas K; Geisler, David J; Cai, Xinran; Yoo, S J B

2012-04-23

We propose and demonstrate silicon photonic integrated circuits (PICs) for free-space spatial-division-multiplexing (SDM) optical transmission with multiplexed orbital angular momentum (OAM) states over a topological charge range of -2 to +2. The silicon PIC fabricated using a CMOS-compatible process exploits tunable-phase arrayed waveguides with vertical grating couplers to achieve space division multiplexing and demultiplexing. The experimental results utilizing two silicon PICs achieve SDM mux/demux bit-error-rate performance for 1‑b/s/Hz, 10-Gb/s binary phase shifted keying (BPSK) data and 2-b/s/Hz, 20-Gb/s quadrature phase shifted keying (QPSK) data for individual and two simultaneous OAM states. © 2012 Optical Society of America

Superposition and detection of two helical beams for optical orbital angular momentum communication

NASA Astrophysics Data System (ADS)

Liu, Yi-Dong; Gao, Chunqing; Gao, Mingwei; Qi, Xiaoqing; Weber, Horst

2008-07-01

A loop-like system with a Dove prism is used to generate a collinear superposition of two helical beams with different azimuthal quantum numbers in this manuscript. After the generation of the helical beams distributed on the circle centered at the optical axis by using a binary amplitude grating, the diffractive field is separated into two polarized ones with the same distribution. Rotated by the Dove prism in the loop-like system in counter directions and combined together, the two fields will generate the collinear superposition of two helical beams in certain direction. The experiment shows consistency with the theoretical analysis. This method has potential applications in optical communication by using orbital angular momentum of laser beams (optical vortices).

On the Lack of Circumbinary Planets Orbiting Isolated Binary Stars

NASA Astrophysics Data System (ADS)

Fleming, David; Barnes, Rory; Graham, David E.; Luger, Rodrigo; Quinn, Thomas R.

2018-04-01

To date, no binary star system with an orbital period less than 7.5 days has been observed to host a circumbinary planet (CBP), a puzzling observation given the thousands of binary stars with orbital periods < 10 days discovered by the Kepler mission (Kirk et al., 2016) and the observational biases that favor their detection (Munoz & Lai, 2015). We outline a mechanism that explains the observed lack of CBPs via coupled stellar-tidal evolution of isolated binary stars. Tidal forces between low-mass, short-period binary stars on the pre-main sequence slow the stellar rotations, transferring rotational angular momentum to the orbit as the stars approach the tidally locked state. This transfer increases the binary orbital period, expanding the region of dynamical instability around the binary, and destabilizing CBPs that tend to preferentially orbit just beyond the initial dynamical stability limit. After the stars tidally lock, we find that angular momentum loss due to magnetic braking can significantly shrink the binary orbit, and hence the region of dynamical stability, over time impacting where surviving CBPs are observed relative to the boundary. We perform simulations over a wide range of parameter space and find that the expansion of the instability region occurs for most plausible initial conditions and that in some cases, the stability semi-major axis doubles from its initial value. We examine the dynamical and observable consequences of a CBP falling within the dynamical instability limit by running N-body simulations of circumbinary planetary systems and find that typically, at least one planet is ejected from the system. We apply our theory to the shortest period Kepler binary that possesses a CBP, Kepler-47, and find that its existence is consistent with our model. Under conservative assumptions, we find that coupled stellar-tidal evolution of pre-main sequence binary stars removes at least one close-in CBP in 87% of multi-planet circumbinary systems.

Element distributions after binary fission of /sup 44/Ti

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pl-dash-baraneta, R.; Belery, P.; Brzychczyk, J.

1986-08-01

Inclusive and coincidence measurements have been performed to study symmetric fragmentation of /sup 44/Ti binary decay from the /sup 32/S+/sup 12/C reaction at 280 MeV incident energy. Element distributions after binary decay were measured. Angular distributions and fragment correlations are presented. Total c.m. kinetic energy for the symmetric products is extracted from our data and from Monte-Carlo model calculations including Q-italic-value fluctuations. This result was compared to liquid drop model calculations and standard fission systematics. Comparison between the experimental value of the total kinetic energy and the rotating liquid-drop model predictions locates the angular momentum window for symmetric splitting ofmore » /sup 44/Ti between 33h-dash-bar and 38h-dash-bar. It also showed that 50% of the corresponding rotational energy contributes to the total kinetic energy values. The dominant reaction mechanism was found to be symmetric splitting followed by evaporation.« less

REVIEWS OF TOPICAL PROBLEMS: The nature of accretion disks of close binary stars: overreflection instability and developed turbulence

NASA Astrophysics Data System (ADS)

Fridman, A. M.; Bisikalo, D. V.

2008-06-01

The current status of the physics of accretion disks in close binary stars is reviewed, with an emphasis on the hydrodynamic overreflection instability, which is a factor leading to the accretion disk turbulence. The estimated turbulent viscosity coefficients are in good agreement with observations and explain the high angular momentum transfer rate and the measured accretion rate. Based on the observations, a power-law spectrum for the developed turbulence is obtained.

Comparing post-Newtonian and numerical relativity precession dynamics

NASA Astrophysics Data System (ADS)

Ossokine, Serguei; Boyle, Michael; Kidder, Lawrence E.; Pfeiffer, Harald P.; Scheel, Mark A.; Szilágyi, Béla

2015-11-01

Binary black-hole systems are expected to be important sources of gravitational waves for upcoming gravitational-wave detectors. If the spins are not colinear with each other or with the orbital angular momentum, these systems exhibit complicated precession dynamics that are imprinted on the gravitational waveform. We develop a new procedure to match the precession dynamics computed by post-Newtonian (PN) theory to those of numerical binary black-hole simulations in full general relativity. For numerical relativity (NR) simulations lasting approximately two precession cycles, we find that the PN and NR predictions for the directions of the orbital angular momentum and the spins agree to better than ˜1 ° with NR during the inspiral, increasing to 5° near merger. Nutation of the orbital plane on the orbital time scale agrees well between NR and PN, whereas nutation of the spin direction shows qualitatively different behavior in PN and NR. We also examine how the PN equations for precession and orbital-phase evolution converge with PN order, and we quantify the impact of various choices for handling partially known PN terms.

Comparing Post-Newtonian and Numerical-Relativity Precession Dynamics

NASA Astrophysics Data System (ADS)

Kidder, Lawrence; Ossokine, Sergei; Boyle, Michael; Pfeiffer, Harald; Scheel, Mark; Szilagyi, Bela

2015-04-01

Binary black-hole systems are expected to be important sources of gravitational waves for upcoming gravitational-wave detectors. If the spins are not colinear with each other or with the orbital angular momentum, these systems exhibit complicated precession dynamics that are imprinted on the gravitational waveform. We develop a new procedure to match the precession dynamics computed by post-Newtonian (PN) theory to those of numerical binary black-hole simulations in full general relativity. For numerical relativity (NR) simulations lasting approximately two precession cycles, we find that the PN and NR predictions for the directions of the orbital angular momentum and the spins agree to better than ~1° with NR during the inspiral, increasing to 5° near merger. Nutation of the orbital plane on the orbital time-scale agrees well between NR and PN, whereas nutation of the spin direction shows qualitatively different behavior in PN and NR. We also examine how the PN equations for precession and orbital-phase evolution converge with PN order, and we quantify the impact of various choices for handling partially known PN terms.

A Comparison of Grid-based and SPH Binary Mass-transfer and Merger Simulations

DOE PAGES

Motl, Patrick M.; Frank, Juhan; Staff, Jan; ...

2017-03-29

There is currently a great amount of interest in the outcomes and astrophysical implications of mergers of double degenerate binaries. In a commonly adopted approximation, the components of such binaries are represented by polytropes with an index of n = 3/2. We present detailed comparisons of stellar mass-transfer and merger simulations of polytropic binaries that have been carried out using two very different numerical algorithms—a finite-volume "grid" code and a smoothed-particle hydrodynamics (SPH) code. We find that there is agreement in both the ultimate outcomes of the evolutions and the intermediate stages if the initial conditions for each code aremore » chosen to match as closely as possible. We find that even with closely matching initial setups, the time it takes to reach a concordant evolution differs between the two codes because the initial depth of contact cannot be matched exactly. There is a general tendency for SPH to yield higher mass transfer rates and faster evolution to the final outcome. Here, we also present comparisons of simulations calculated from two different energy equations: in one series, we assume a polytropic equation of state and in the other series an ideal gas equation of state. In the latter series of simulations, an atmosphere forms around the accretor, which can exchange angular momentum and cause a more rapid loss of orbital angular momentum. In the simulations presented here, the effect of the ideal equation of state is to de-stabilize the binary in both SPH and grid simulations, but the effect is more pronounced in the grid code.« less

An Argument for Weakly Magnetized, Slowly Rotating Progenitors of Long Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Moreno Méndez, Enrique

2014-01-01

Using binary evolution with Case-C mass transfer, the spins of several black holes (BHs) in X-ray binaries (XBs) have been predicted and confirmed (three cases) by observations. The rotational energy of these BHs is sufficient to power up long gamma-ray bursts (GRBs) and hypernovae (HNe) and still leave a Kerr BH behind. However, strong magnetic fields and/or dynamo effects in the interior of such stars deplete their cores from angular momentum preventing the formation of collapsars. Thus, even though binaries can produce Kerr BHs, most of their rotation is acquired from the stellar mantle, with a long delay between BH formation and spin up. Such binaries would not form GRBs. We study whether the conditions required to produce GRBs can be met by the progenitors of such BHs. Tidal-synchronization and Alfvén timescales are compared for magnetic fields of different intensities threading He stars. A search is made for a magnetic field range that allows tidal spin up all the way in to the stellar core but prevents its slow down during differential rotation phases. The energetics for producing a strong magnetic field during core collapse, which may allow for a GRB central engine, are also estimated. An observationally reasonable choice of parameters is found (B <~ 102 G threading a slowly rotating He star) that allows Fe cores to retain substantial angular momentum. Thus, the Case-C mass-transfer binary channel is capable of explaining long GRBs. However, the progenitors must have low initial spin and low internal magnetic field throughout their H-burning and He-burning phases.

The Light-time Effect in the Eclipsing Binaries with Early-type Components U CrB and RW Tau

NASA Astrophysics Data System (ADS)

Khaliullina, A. I.

2018-04-01

A detailed study of the orbital-period variations of the Algol-type eclipsing binaries with earlyspectral- type primary components U CrB and RW Tau has been performed. The period variations in both systems can be described as a superposition of secular and cyclic variations of the period. A secular period increase at a rate of 2.58d × 10-7/year is observed for U CrB, which can be explained if there is a uniform flow of matter from the lower-mass to the higher-mass component, with the total angular momentum conserved. RW Tau features a secular period decrease at a rate of -8.6d × 10-7/year; this could be due to a loss of angular momentum by the binary due to magnetic braking. The cyclic orbital-period variations of U CrB and RWTau can be explained by the motion of the eclipsing binary systems along their long-period orbits. In U CrB, this implies that the eclipsing binary moves with a period of 91.3 years around a third body with mass M 3 > 1.13 M ⊙; in RW Tau, the period of the motion around the third body is 66.6 years, and the mass of the third body is M 3 > 1.24 M ⊙. It also cannot be ruled out that the variations are due to the magnetic cycles of the late-type secondaries. The residual period variations could be a superposition of variations due to non-stationary ejection of matter and effects due to magnetic cycles.

GW170817 and the Prospect of Forming Supramassive Remnants in Neutron Star Mergers

NASA Astrophysics Data System (ADS)

Ma, Peng-Xiong; Jiang, Jin-Liang; Wang, Hao; Jin, Zhi-Ping; Fan, Yi-Zhong; Wei, Da-Ming

2018-05-01

The gravitational wave data of GW170817 favor the equation of state (EoS) models that predict compact neutron stars (NSs), consistent with the radius constraints from X-ray observations. Motivated by such remarkable progress, we examine the fate of the remnants formed in NS mergers and focus on the roles of the angular momentum and the mass distribution of the binary NSs. In the mass-shedding limit (for which the dimensionless angular momentum equals the Keplerian value, i.e., j = j Kep), the adopted seven EoS models, except for H4 and ALF2, yield supramassive NSs in more than half of the mergers. However, for j ≲ 0.7 j Kep, the presence or absence of a non-negligible fraction of supramassive NSs formed in the mergers depends sensitively on both the EoS and the mass distribution of the binary systems. The NS mergers with a total gravitational mass ≤ 2.6 M ⊙ are found to be able to shed valuable light on both the EoS model and the angular momentum of the remnants if supramassive NSs are still absent. We have also discussed the uncertainty on estimating the maximum gravitational mass of nonrotating NSs (M max) due to the unknown j of the precollapse remnants. With the data of GW170817 and the assumption of the mass loss of 0.03 M ⊙, we have M max < (2.19, 2.32) M ⊙ (90% confidence level) for j = (1.0, 0.8) j Kep, respectively.

Formation and Evolution of X-ray Binaries

NASA Astrophysics Data System (ADS)

Shao, Y.

2017-07-01

X-ray binaries are a class of binary systems, in which the accretor is a compact star (i.e., black hole, neutron star, or white dwarf). They are one of the most important objects in the universe, which can be used to study not only binary evolution but also accretion disks and compact stars. Statistical investigations of these binaries help to understand the formation and evolution of galaxies, and sometimes provide useful constraints on the cosmological models. The goal of this thesis is to investigate the formation and evolution processes of X-ray binaries including Be/X-ray binaries, low-mass X-ray binaries (LMXBs), ultraluminous X-ray sources (ULXs), and cataclysmic variables. In Chapter 1 we give a brief review on the basic knowledge of the binary evolution. In Chapter 2 we discuss the formation of Be stars through binary interaction. In this chapter we investigate the formation of Be stars resulting from mass transfer in binaries in the Galaxy. Using binary evolution and population synthesis calculations, we find that in Be/neutron star binaries the Be stars have a lower limit of mass ˜ 8 M⊙ if they are formed by a stable (i.e., without the occurrence of common envelope evolution) and nonconservative mass transfer. We demonstrate that the isolated Be stars may originate from both mergers of two main-sequence stars and disrupted Be binaries during the supernova explosions of the primary stars, but mergers seem to play a much more important role. Finally the fraction of Be stars produced by binary interactions in all B type stars can be as high as ˜ 13%-30% , implying that most of Be stars may result from binary interaction. In Chapter 3 we show the evolution of intermediate- and low-mass X-ray binaries (I/LMXBs) and the formation of millisecond pulsars. Comparing the calculated results with the observations of binary radio pulsars, we report the following results: (1) The allowed parameter space for forming binary pulsars in the initial orbital period-donor mass plane increases with the increasing neutron star mass. This may help to explain why some millisecond pulsars with orbital periods longer than ˜ 60 d seem to have less massive white dwarfs than expected. Alternatively, some of these wide binary pulsars may be formed through mass transfer driven by planet/brown dwarf-involved common envelope evolution; (2) Some of the pulsars in compact binaries might have evolved from intermediate-mass X-ray binaries with an anomalous magnetic braking; (3) The equilibrium spin periods of neutron stars in low-mass X-ray binaries are in general shorter than the observed spin periods of binary pulsars by more than one order of magnitude, suggesting that either the simple equilibrium spin model does not apply, or there are other mechanisms/processes spinning down the neutron stars. In Chapter 4, angular momentum loss mechanisms in the cataclysmic variables below the period gap are presented. By considering several kinds of consequential angular momentum loss mechanisms, we find that neither isotropic wind from the white dwarf nor outflow from the L1 point can explain the extra angular momentum loss rate, while an ouflow from the L2 point or a circumbinary disk can effectively extract the angular momentum provided that ˜ 15%-45% of the transferred mass is lost from the binary. A more promising mechanism is a circumbinary disk exerting a gravitational torque on the binary. In this case the mass loss fraction can be as low as ≲ 10-3. In Chapter 5 we present a study on the population of ultraluminous X-ray sources with an accreting neutron star. Most ULXs are believed to be X-ray binary systems, but previous observational and theoretical studies tend to prefer a black hole rather than a neutron star accretor. The recent discovery of 1.37 s pulsations from the ULX M82 X-2 has established its nature as a magnetized neutron star. In this chapter we model the formation history of neutron star ULXs in an M82- or Milky Way-like galaxy, by use of both binary population synthesis and detailed binary evolution calculations. We find that the birthrate is around 10-4 yr-1 for the incipient X-ray binaries in both cases. We demonstrate the distribution of the ULX population in the donor mass - orbital period plane. Our results suggest that, compared with black hole X-ray binaries, neutron star X-ray binaries may significantly contribute to the ULX population, and high/intermediate-mass X-ray binaries dominate the neutron star ULX population in M82/Milky Way-like galaxies, respectively. In Chapter 6, the population of intermediate- and low-mass X-ray binaries in the Galaxy is explored. We investigate the formation and evolutionary sequences of Galactic intermediate- and low-mass X-ray binaries by combining binary population synthesis (BPS) and detailed stellar evolutionary calculations. Using an updated BPS code we compute the evolution of massive binaries that leads to the formation of incipient I/LMXBs, and present their distribution in the initial donor mass vs. initial orbital period diagram. We then follow the evolution of I/LMXBs until the formation of binary millisecond pulsars (BMSPs). We show that during the evolution of I/LMXBs they are likely to be observed as relatively compact binaries. The resultant BMSPs have orbital periods ranging from about 1 day to a few hundred days. These features are consistent with observations of LMXBs and BMSPs. We also confirm the discrepancies between theoretical predictions and observations mentioned in the literature, that is, the theoretical average mass transfer rates of LMXBs are considerably lower than observed, and the number of BMSPs with orbital periods ˜ 0.1-1 \\unit{d} is severely underestimated. Both imply that something is missing in the modeling of LMXBs, which is likely to be related to the mechanisms of the orbital angular momentum loss. Finally in Chapter 7 we summarize our results and give the prospects for the future work.

Polar alignment of a protoplanetary disc around an eccentric binary II: Effect of binary and disc parameters

NASA Astrophysics Data System (ADS)

Martin, Rebecca G.; Lubow, Stephen H.

2018-06-01

In a recent paper Martin & Lubow showed that a circumbinary disc around an eccentric binary can undergo damped nodal oscillations that lead to the polar (perpendicular) alignment of the disc relative to the binary orbit. The disc angular momentum vector aligns to the eccentricity vector of the binary. We explore the robustness of this mechanism for a low mass disc (0.001 of the binary mass) and its dependence on system parameters by means of hydrodynamic disc simulations. We describe how the evolution depends upon the disc viscosity, temperature, size, binary mass ratio, orbital eccentricity and inclination. We compare results with predictions of linear theory. We show that polar alignment of a low mass disc may occur over a wide range of binary-disc parameters. We discuss the application of our results to the formation of planetary systems around eccentric binary stars.

Plunge waveforms from inspiralling binary black holes.

PubMed

Baker, J; Brügmann, B; Campanelli, M; Lousto, C O; Takahashi, R

2001-09-17

We study the coalescence of nonspinning binary black holes from near the innermost stable circular orbit down to the final single rotating black hole. We use a technique that combines the full numerical approach to solve the Einstein equations, applied in the truly nonlinear regime, and linearized perturbation theory around the final distorted single black hole at later times. We compute the plunge waveforms, which present a non-negligible signal lasting for t approximately 100M showing early nonlinear ringing, and we obtain estimates for the total gravitational energy and angular momentum radiated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soker, Noam, E-mail: soker@physics.technion.ac.il

I suggest a spiral-in process in which a stellar companion grazes the envelope of a giant star while both the orbital separation and the giant radius shrink simultaneously, forming a close binary system. The binary system might be viewed as evolving in a constant state of 'just entering a common envelope (CE) phase.' In cases where this process takes place, it can be an alternative to CE evolution where the secondary star is immersed in the giant's envelope. Grazing envelope evolution (GEE) is made possible only if the companion manages to accrete mass at a high rate and launches jetsmore » that remove the outskirts of the giant envelope, hence preventing the formation of a CE. The high accretion rate is made possible by the accretion disk launching jets which efficiently carry the excess angular momentum and energy from the accreted mass. The orbital decay itself is caused by the gravitational interaction of the secondary star with the envelope inward of its orbit, i.e., dynamical friction (gravitational tide). Mass loss through the second Lagrangian point can carry additional angular momentum and envelope mass. The GEE lasts for tens to hundreds of years. The high accretion rate, with peaks lasting from months to years, might lead to a bright object referred to as the intermediate luminosity optical transient (Red Novae; Red Transients). A bipolar nebula and/or equatorial ring are formed around the binary remnant.« less

A Comparison of Grid-based and SPH Binary Mass-transfer and Merger Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Motl, Patrick M.; Frank, Juhan; Clayton, Geoffrey C.

2017-04-01

There is currently a great amount of interest in the outcomes and astrophysical implications of mergers of double degenerate binaries. In a commonly adopted approximation, the components of such binaries are represented by polytropes with an index of n  = 3/2. We present detailed comparisons of stellar mass-transfer and merger simulations of polytropic binaries that have been carried out using two very different numerical algorithms—a finite-volume “grid” code and a smoothed-particle hydrodynamics (SPH) code. We find that there is agreement in both the ultimate outcomes of the evolutions and the intermediate stages if the initial conditions for each code are chosen to matchmore » as closely as possible. We find that even with closely matching initial setups, the time it takes to reach a concordant evolution differs between the two codes because the initial depth of contact cannot be matched exactly. There is a general tendency for SPH to yield higher mass transfer rates and faster evolution to the final outcome. We also present comparisons of simulations calculated from two different energy equations: in one series, we assume a polytropic equation of state and in the other series an ideal gas equation of state. In the latter series of simulations, an atmosphere forms around the accretor, which can exchange angular momentum and cause a more rapid loss of orbital angular momentum. In the simulations presented here, the effect of the ideal equation of state is to de-stabilize the binary in both SPH and grid simulations, but the effect is more pronounced in the grid code.« less

Strong disk winds traced throughout outbursts in black-hole X-ray binaries

NASA Astrophysics Data System (ADS)

Tetarenko, B. E.; Lasota, J.-P.; Heinke, C. O.; Dubus, G.; Sivakoff, G. R.

2018-02-01

Recurring outbursts associated with matter flowing onto compact stellar remnants (such as black holes, neutron stars and white dwarfs) in close binary systems provide a way of constraining the poorly understood accretion process. The light curves of these outbursts are shaped by the efficiency of angular-momentum (and thus mass) transport in the accretion disks, which has traditionally been encoded in a viscosity parameter, α. Numerical simulations of the magneto-rotational instability that is believed to be the physical mechanism behind this transport yield values of α of roughly 0.1–0.2, consistent with values determined from observations of accreting white dwarfs. Equivalent viscosity parameters have hitherto not been estimated for disks around neutron stars or black holes. Here we report the results of an analysis of archival X-ray light curves of 21 outbursts in black-hole X-ray binaries. By applying a Bayesian approach to a model of accretion, we determine corresponding values of α of around 0.2–1.0. These high values may be interpreted as an indication either of a very high intrinsic rate of angular-momentum transport in the disk, which could be sustained by the magneto-rotational instability only if a large-scale magnetic field threads the disk, or that mass is being lost from the disk through substantial outflows, which strongly shape the outburst in the black-hole X-ray binary. The lack of correlation between our estimates of α and the accretion state of the binaries implies that such outflows can remove a substantial fraction of the disk mass in all accretion states and therefore suggests that the outflows correspond to magnetically driven disk winds rather than thermally driven ones, which require specific radiative conditions.

Strong disk winds traced throughout outbursts in black-hole X-ray binaries.

PubMed

Tetarenko, B E; Lasota, J-P; Heinke, C O; Dubus, G; Sivakoff, G R

2018-02-01

Recurring outbursts associated with matter flowing onto compact stellar remnants (such as black holes, neutron stars and white dwarfs) in close binary systems provide a way of constraining the poorly understood accretion process. The light curves of these outbursts are shaped by the efficiency of angular-momentum (and thus mass) transport in the accretion disks, which has traditionally been encoded in a viscosity parameter, α. Numerical simulations of the magneto-rotational instability that is believed to be the physical mechanism behind this transport yield values of α of roughly 0.1-0.2, consistent with values determined from observations of accreting white dwarfs. Equivalent viscosity parameters have hitherto not been estimated for disks around neutron stars or black holes. Here we report the results of an analysis of archival X-ray light curves of 21 outbursts in black-hole X-ray binaries. By applying a Bayesian approach to a model of accretion, we determine corresponding values of α of around 0.2-1.0. These high values may be interpreted as an indication either of a very high intrinsic rate of angular-momentum transport in the disk, which could be sustained by the magneto-rotational instability only if a large-scale magnetic field threads the disk, or that mass is being lost from the disk through substantial outflows, which strongly shape the outburst in the black-hole X-ray binary. The lack of correlation between our estimates of α and the accretion state of the binaries implies that such outflows can remove a substantial fraction of the disk mass in all accretion states and therefore suggests that the outflows correspond to magnetically driven disk winds rather than thermally driven ones, which require specific radiative conditions.

An argument for weakly magnetized, slowly rotating progenitors of long gamma-ray bursts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreno Méndez, Enrique, E-mail: enriquemm@astro.unam.mx

2014-01-20

Using binary evolution with Case-C mass transfer, the spins of several black holes (BHs) in X-ray binaries (XBs) have been predicted and confirmed (three cases) by observations. The rotational energy of these BHs is sufficient to power up long gamma-ray bursts (GRBs) and hypernovae (HNe) and still leave a Kerr BH behind. However, strong magnetic fields and/or dynamo effects in the interior of such stars deplete their cores from angular momentum preventing the formation of collapsars. Thus, even though binaries can produce Kerr BHs, most of their rotation is acquired from the stellar mantle, with a long delay between BHmore » formation and spin up. Such binaries would not form GRBs. We study whether the conditions required to produce GRBs can be met by the progenitors of such BHs. Tidal-synchronization and Alfvén timescales are compared for magnetic fields of different intensities threading He stars. A search is made for a magnetic field range that allows tidal spin up all the way in to the stellar core but prevents its slow down during differential rotation phases. The energetics for producing a strong magnetic field during core collapse, which may allow for a GRB central engine, are also estimated. An observationally reasonable choice of parameters is found (B ≲ 10{sup 2} G threading a slowly rotating He star) that allows Fe cores to retain substantial angular momentum. Thus, the Case-C mass-transfer binary channel is capable of explaining long GRBs. However, the progenitors must have low initial spin and low internal magnetic field throughout their H-burning and He-burning phases.« less

Neutron transfer in the C 13 + Au 197 reaction from gold isotope residuals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daub, B. H.; Bleuel, D. L.; Wiedeking, M.

Residual gold nuclei were produced in this paper via neutron transfer at multiple energies using a 130-MeV 13C beam incident on a stacked-foil target consisting of alternating layers of 197Au and 27Al. Production cross sections, over an energy range of 56 to 129 MeV, for seven gold isotopes and two gold isomers were determined through activation analysis. By using the Wilczynski binary transfer model with a modified version of the recoil formula and a standard evaporation model, we were able to reproduce the isotopic production cross sections at high beam energy, with some disagreement at lower beam energies. Finally, thismore » limiting angular momentum model does not predict the transfer of sufficient angular momentum to reproduce the observed isomeric populations.« less

Neutron transfer in the C 13 + Au 197 reaction from gold isotope residuals

DOE PAGES

Daub, B. H.; Bleuel, D. L.; Wiedeking, M.; ...

2017-08-01

Residual gold nuclei were produced in this paper via neutron transfer at multiple energies using a 130-MeV 13C beam incident on a stacked-foil target consisting of alternating layers of 197Au and 27Al. Production cross sections, over an energy range of 56 to 129 MeV, for seven gold isotopes and two gold isomers were determined through activation analysis. By using the Wilczynski binary transfer model with a modified version of the recoil formula and a standard evaporation model, we were able to reproduce the isotopic production cross sections at high beam energy, with some disagreement at lower beam energies. Finally, thismore » limiting angular momentum model does not predict the transfer of sufficient angular momentum to reproduce the observed isomeric populations.« less

Turbulence-induced channel crosstalk in an orbital angular momentum-multiplexed free-space optical link

NASA Astrophysics Data System (ADS)

Anguita, Jaime A.; Neifeld, Mark A.; Vasic, Bane V.

2008-05-01

A multichannel free-space optical (FSO) communication system based on orbital angular momentum (OAM)-carrying beams is studied. We numerically analyze the effects of atmospheric turbulence on the system and find that turbulence induces attenuation and crosstalk among channels. Based on a model in which the constituent channels are binary symmetric and crosstalk is a Gaussian noise source, we find optimal sets of OAM states at each turbulence condition studied and determine the aggregate capacity of the multichannel system at those conditions. OAM-multiplexed FSO systems that operate in the weak turbulence regime are found to offer good performance. We verify that the aggregate capacity decreases as the turbulence increases. A per-channel bit-error rate evaluation is presented to show the uneven effects of crosstalk on the constituent channels.

The topology of the regularized integral surfaces of the 3-body problem

NASA Technical Reports Server (NTRS)

Easton, R.

1971-01-01

Momentum, angular momentum, and energy of integral surfaces in the planar three-body problem are considered. The end points of orbits which cross an isolating block are identified. It is shown that this identification has a unique extension to an identification which pairs the end points of orbits entering the block and which end in a binary collision with the end points of orbits leaving the block and which come from a binary collision. The problem of regularization is that of showing that the identification of the end points of crossing orbits has a continuous, unique extension. The regularized phase space for the three-body problem was obtained, as were regularized integral surfaces for the problem on which the three-body equations of motion induce flows. Finally the topology of these surfaces is described.

Photometric study of the eclipsing blue straggler V205 in the globular cluster NGC 5139

NASA Astrophysics Data System (ADS)

Li, K.

2018-02-01

B and V light curves of an EA-type binary V205 in the globular cluster NGC 5139 are analyzed by the W-D program. We found that V205 is possibly a detached binary and the mass ratio is 0.1596. The secondary component is touching or nearly touching its inner Roche Lobe. By studying the O - C diagram of V205, we discovered that the orbital period is continuously decrease at a rate of dp / dt = - 1.89(± 0.01) ×10-7 d yr-1 and should be caused by angular momentum and mass loss. The angular momentum loss will drive it evolve into a contact binary. Since V205 is a proper motion member of NGC 5139, we estimated its absolute parameters based on the distance modulus of the cluster and determined that: a = 2.50R⊙ , M1 = 0.76M⊙ , R1 = 1.14R⊙ , L1 = 5.46L⊙ , M2 = 0.12M⊙ , R2 = 0.52R⊙ , and L2 = 0.70L⊙ . V205 occupied the blue straggler stars on the color-magnitude diagram of NGC 5139. It is an eclipsing blue straggler and is most possibly formed by mass transfer between the two components. Since original short-period systems similar to V205 should be evolved in such a long life time of the globular cluster, the short-period binary should undergo special evolutionary stages. High accuracy photometric and high resolution spectral observations are essential for this unusual system.

High-resolution observations of IRAS 08544-4431. Detection of a disk orbiting a post-AGB star and of a slow disk wind

NASA Astrophysics Data System (ADS)

Bujarrabal, V.; Castro-Carrizo, A.; Winckel, H. Van; Alcolea, J.; Contreras, C. Sánchez; Santander-García, M.; Hillen, M.

2018-06-01

Context. Aims: In order to study the effects of rotating disks in the post-asymptotic giant branch (post-AGB) evolution, we observe a class of binary post-AGB stars that seem to be systematically surrounded by equatorial disks and slow outflows. Although the rotating dynamics had only been well identified in three cases, the study of such structures is thought to be fundamental to the understanding of the formation of disks in various phases of the late evolution of binary stars and the ejection of planetary nebulae from evolved stars. Methods: We present ALMA maps of 12CO and 13CO J = 3-2 lines in the source IRAS 08544-4431, which belongs to the above mentioned class of objects. We analyzed the data by means of nebula models, which account for the expectedly composite source and can reproduce the data. From our modeling, we estimated the main nebula parameters, including the structure and dynamics and the density and temperature distributions. We discuss the uncertainties of the derived values and, in particular, their dependence on the distance. Results: Our observations reveal the presence of an equatorial disk in rotation; a low-velocity outflow is also found, probably formed of gas expelled from the disk. The main characteristics of our observations and modeling of IRAS 08544-4431 are similar to those of better studied objects, confirming our interpretation. The disk rotation indicates a total central mass of about 1.8 M⊙, for a distance of 1100 pc. The disk is found to be relatively extended and has a typical diameter of 4 × 1016 cm. The total nebular mass is 2 × 10-2 M⊙, of which 90% corresponds to the disk. Assuming that the outflow is due to mass loss from the disk, we derive a disk lifetime of 10 000 yr. The disk angular momentum is found to be comparable to that of the binary system at present. Assuming that the disk angular momentum was transferred from the binary system, as expected, the high values of the disk angular momentum in this and other similar disks suggest that the size of the stellar orbits has significantly decreased as a consequence of disk formation.

Inferences about Supernova Physics from Gravitational-Wave Measurements: GW151226 Spin Misalignment as an Indicator of Strong Black-Hole Natal Kicks

NASA Astrophysics Data System (ADS)

O'Shaughnessy, Richard; Gerosa, Davide; Wysocki, Daniel

2017-07-01

The inferred parameters of the binary black hole GW151226 are consistent with nonzero spin for the most massive black hole, misaligned from the binary's orbital angular momentum. If the black holes formed through isolated binary evolution from an initially aligned binary star, this misalignment would then arise from a natal kick imparted to the first-born black hole at its birth during stellar collapse. We use simple kinematic arguments to constrain the characteristic magnitude of this kick, and find that a natal kick vk≳50 km /s must be imparted to the black hole at birth to produce misalignments consistent with GW151226. Such large natal kicks exceed those adopted by default in most of the current supernova and binary evolution models.

Inferences about Supernova Physics from Gravitational-Wave Measurements: GW151226 Spin Misalignment as an Indicator of Strong Black-Hole Natal Kicks.

PubMed

O'Shaughnessy, Richard; Gerosa, Davide; Wysocki, Daniel

2017-07-07

The inferred parameters of the binary black hole GW151226 are consistent with nonzero spin for the most massive black hole, misaligned from the binary's orbital angular momentum. If the black holes formed through isolated binary evolution from an initially aligned binary star, this misalignment would then arise from a natal kick imparted to the first-born black hole at its birth during stellar collapse. We use simple kinematic arguments to constrain the characteristic magnitude of this kick, and find that a natal kick v_{k}≳50  km/s must be imparted to the black hole at birth to produce misalignments consistent with GW151226. Such large natal kicks exceed those adopted by default in most of the current supernova and binary evolution models.

Measuring Parameters of Massive Black Hole Binaries with Partially-Aligned Spins

NASA Technical Reports Server (NTRS)

Lang, Ryan N.; Hughes, Scott A.; Cornish, Neil J.

2010-01-01

It is important to understand how well the gravitational-wave observatory LISA can measure parameters of massive black hole binaries. It has been shown that including spin precession in the waveform breaks degeneracies and produces smaller expected parameter errors than a simpler, precession-free analysis. However, recent work has shown that gas in binaries can partially align the spins with the orbital angular momentum, thus reducing the precession effect. We show how this degrades the earlier results, producing more pessimistic errors in gaseous mergers. However, we then add higher harmonics to the signal model; these also break degeneracies, but they are not affected by the presence of gas. The harmonics often restore the errors in partially-aligned binaries to the same as, or better than/ those that are obtained for fully precessing binaries with no harmonics. Finally, we investigate what LISA measurements of spin alignment can tell us about the nature of gas around a binary,

Long term evolution of surface features on the unusual close binary V361 Lyr

NASA Astrophysics Data System (ADS)

Lister, T. A.

2009-02-01

V361 Lyr has been recognized as an unusual, possibly unique, pre-contact binary which is though to be evolving from a detached binary system into a W UMa contact binary system due to Angular Momentum Loss (AML) and mass transfer. The mass transfer and resulting hot spot on the secondary star allow the physics of accretion to be studied without the normal difficulties of disks and winds that are present in T Tauri stars. I present light curves obtained over a 10 year period as part of long term monitoring program obtained with a variety of telescopes, collect all available times of minima from the literature along with those determined from the light curves and determine the rate of period change.

Gravitational waves from neutron star excitations in a binary inspiral

NASA Astrophysics Data System (ADS)

Parisi, Alessandro; Sturani, Riccardo

2018-02-01

In the context of a binary inspiral of mixed neutron star-black hole systems, we investigate the excitation of the neutron star oscillation modes by the orbital motion. We study generic eccentric orbits and show that tidal interaction can excite the f -mode oscillations of the star by computing the amount of energy and angular momentum deposited into the star by the orbital motion tidal forces via closed form analytic expressions. We study the f -mode oscillations of cold neutron stars using recent microscopic nuclear equations of state, and we compute their imprint into the emitted gravitational waves.

The origin of ultra-compact binaries

NASA Technical Reports Server (NTRS)

Hachisu, Izumi; Miyaji, Shigeki; Saio, Hideyuki

1987-01-01

The origin of ultra-compact binaries composed of a neutron star and a low-mass (about 0.06 solar mass) white dwarf is considered. Taking account of the systemic losses of mass and angular momentum, it was found that a serious difficulty exists in the scenarios which involve tidal captures of a normal star (a main sequence star or a red giant) by a neutron star. This difficulty can be avoided if a red giant star is captured by a massive white dwarf (M is approx. greater than 1.2 solar masses), which becomes a neutron star through the accretion induced collapse.

Physical properties and catalog of EW-type eclipsing binaries observed by LAMOST

NASA Astrophysics Data System (ADS)

Qian, Sheng-Bang; He, Jia-Jia; Zhang, Jia; Zhu, Li-Ying; Shi, Xiang-Dong; Zhao, Er-Gang; Zhou, Xiao

2017-08-01

EW-type eclipsing binaries (hereafter called EWs) are strong interacting systems in which both component stars usually fill their critical Roche lobes and share a common envelope. Numerous EWs were discovered by several deep photometric surveys and there were about 40 785 EW-type binary systems listed in the international variable star index (VSX) by 2017 March 13. 7938 of them were observed with LAMOST by 2016 November 30 and their spectral types were identified. Stellar atmospheric parameters of 5363 EW-type binary stars were determined based on good spectroscopic observations. In the paper, those EWs are cataloged and their properties are analyzed. The distributions of orbital period (P), effective temperature (T), gravitational acceleration (log(g)), metallicity ([Fe/H]) and radial velocity (RV) are presented for these observed EW-type systems. It is shown that about 80.6% of sample stars have metallicity below zero, indicating that EW-type systems are old stellar populations. This is in agreement with the conclusion that EW binaries are formed from moderately close binaries through angular momentum loss via magnetic braking that takes a few hundred million to a few billion years. The unusually high metallicities of a few percent of EWs may be caused by contamination of material from the evolution of unseen neutron stars or black holes in the systems. The correlations between orbital period and effective temperature, gravitational acceleration and metallicity are presented and their scatters are mainly caused by (i) the presence of third bodies and (ii) sometimes wrongly determined periods. It is shown that some EWs contain evolved component stars and the physical properties of EWs mainly depend on their orbital periods. It is found that extremely short-period EWs may be older than their long-period cousins because they have lower metallicities. This reveals that they have a longer timescale of pre-contact evolution and their formation and evolution aremainly driven by angular momentum loss via magnetic braking.

The magnetic nature of disk accretion onto black holes.

PubMed

Miller, Jon M; Raymond, John; Fabian, Andy; Steeghs, Danny; Homan, Jeroen; Reynolds, Chris; van der Klis, Michiel; Wijnands, Rudy

2006-06-22

Although disk accretion onto compact objects-white dwarfs, neutron stars and black holes-is central to much of high-energy astrophysics, the mechanisms that enable this process have remained observationally difficult to determine. Accretion disks must transfer angular momentum in order for matter to travel radially inward onto the compact object. Internal viscosity from magnetic processes and disk winds can both in principle transfer angular momentum, but hitherto we lacked evidence that either occurs. Here we report that an X-ray-absorbing wind discovered in an observation of the stellar-mass black hole binary GRO J1655 - 40 (ref. 6) must be powered by a magnetic process that can also drive accretion through the disk. Detailed spectral analysis and modelling of the wind shows that it can only be powered by pressure generated by magnetic viscosity internal to the disk or magnetocentrifugal forces. This result demonstrates that disk accretion onto black holes is a fundamentally magnetic process.

Stern-Gerlach-like approach to electron orbital angular momentum measurement

DOE PAGES

Harvey, Tyler R.; Grillo, Vincenzo; McMorran, Benjamin J.

2017-02-28

Many methods now exist to prepare free electrons into orbital-angular-momentum states, and the predicted applications of these electron states as probes of materials and scattering processes are numerous. The development of electron orbital-angular-momentum measurement techniques has lagged behind. We show that coupling between electron orbital angular momentum and a spatially varying magnetic field produces an angular-momentum-dependent focusing effect. We propose a design for an orbital-angular-momentum measurement device built on this principle. As the method of measurement is noninterferometric, the device works equally well for mixed, superposed, and pure final orbital-angular-momentum states. The energy and orbital-angular-momentum distributions of inelastically scattered electronsmore » may be simultaneously measurable with this technique.« less

Stern-Gerlach-like approach to electron orbital angular momentum measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harvey, Tyler R.; Grillo, Vincenzo; McMorran, Benjamin J.

Many methods now exist to prepare free electrons into orbital-angular-momentum states, and the predicted applications of these electron states as probes of materials and scattering processes are numerous. The development of electron orbital-angular-momentum measurement techniques has lagged behind. We show that coupling between electron orbital angular momentum and a spatially varying magnetic field produces an angular-momentum-dependent focusing effect. We propose a design for an orbital-angular-momentum measurement device built on this principle. As the method of measurement is noninterferometric, the device works equally well for mixed, superposed, and pure final orbital-angular-momentum states. The energy and orbital-angular-momentum distributions of inelastically scattered electronsmore » may be simultaneously measurable with this technique.« less

A New Equilibrium State for Singly Synchronous Binary Asteroids

NASA Astrophysics Data System (ADS)

Golubov, Oleksiy; Unukovych, Vladyslav; Scheeres, Daniel J.

2018-04-01

The evolution of rotation states of small asteroids is governed by the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect, nonetheless some asteroids can stop their YORP evolution by attaining a stable equilibrium. The same is true for binary asteroids subjected to the binary YORP (BYORP) effect. Here we discuss a new type of equilibrium that combines these two, which is possible in a singly synchronous binary system. This equilibrium occurs when the normal YORP, the tangential YORP, and the BYORP compensate each other, and tidal torques distribute the angular momentum between the components of the system and dissipate energy. If unperturbed, such a system would remain singly synchronous in perpetuity with constant spin and orbit rates, as the tidal torques dissipate the incoming energy from impinging sunlight at the same rate. The probability of the existence of this kind of equilibrium in a binary system is found to be on the order of a few percent.

Induced Ellipticity for Inspiraling Binary Systems

NASA Astrophysics Data System (ADS)

Randall, Lisa; Xianyu, Zhong-Zhi

2018-01-01

Although gravitational waves tend to erase eccentricity of an inspiraling binary system, ellipticity can be generated in the presence of surrounding matter. We present a semianalytical method for understanding the eccentricity distribution of binary black holes (BHs) in the presence of a supermassive BH in a galactic center. Given a matter distribution, we show how to determine the resultant eccentricity analytically in the presence of both tidal forces and evaporation up to one cutoff and one matter-distribution-independent function, paving the way for understanding the environment of detected inspiraling BHs. We furthermore generalize Kozai–Lidov dynamics to situations where perturbation theory breaks down for short time intervals, allowing more general angular momentum exchange, such that eccentricity is generated even when all bodies orbit in the same plane.

Double-core evolution. 5: Three-dimensional effects in the merger of a red giant with a dwarf companion

NASA Technical Reports Server (NTRS)

Terman, James L.; Taam, Ronald E.; Hernquist, Lars

1994-01-01

The evolution of the common envelope phase of a binary system consisting of a 4.67 solar mass red giant and a 0.94 solar mass dwarf is studied using smoothed particle hydrodynamics. We demonstrate that the three-dimensional effects associated with the gravitational tidal torques lead to a rapid decay of the orbit on timescales approximately less than 1 yr. The relative orbit of the two cores in the common envelope is initally eccentric and tends to circularize as the orbital separation of the two cores decreases. The angular momentum lost from the orbital motion is distributed throughout the common envelope, and the double core does not evolve to a state of co-rotation for the evolutionary time followed. The energy dissipated from the relative orbit and deposited in the common envelope results in the ejection of approximately 13% of the mass of the envelope. The mass is ejected in all directions, but there is a preference for mass ejection in the orbital plane of the binary system. For example, approximately 80% of the ejected mass lies within 30 deg of the binary orbital plane. Because gravitational forces are long range, most of the energy and angular momentum is imparted to a small fraction of the common envelope resulting in an efficiency of the mass ejection process of approximately 15%. The core of the red giant executes significant displacement with respect to the center of mass of the system and contributes nearly equally to the total energy dissipation rate during the latter phases of the evolution. The degree of departure from synchronism of the initial binary system can be an important property of the system which can affect the outcome of the common envelope phase.

Whole-body angular momentum during stair ascent and descent.

PubMed

Silverman, Anne K; Neptune, Richard R; Sinitski, Emily H; Wilken, Jason M

2014-04-01

The generation of whole-body angular momentum is essential in many locomotor tasks and must be regulated in order to maintain dynamic balance. However, angular momentum has not been investigated during stair walking, which is an activity that presents a biomechanical challenge for balance-impaired populations. We investigated three-dimensional whole-body angular momentum during stair ascent and descent and compared it to level walking. Three-dimensional body-segment kinematic and ground reaction force (GRF) data were collected from 30 healthy subjects. Angular momentum was calculated using a 13-segment whole-body model. GRFs, external moment arms and net joint moments were used to interpret the angular momentum results. The range of frontal plane angular momentum was greater for stair ascent relative to level walking. In the transverse and sagittal planes, the range of angular momentum was smaller in stair ascent and descent relative to level walking. Significant differences were also found in the ground reaction forces, external moment arms and net joint moments. The sagittal plane angular momentum results suggest that individuals alter angular momentum to effectively counteract potential trips during stair ascent, and reduce the range of angular momentum to avoid falling forward during stair descent. Further, significant differences in joint moments suggest potential neuromuscular mechanisms that account for the differences in angular momentum between walking conditions. These results provide a baseline for comparison to impaired populations that have difficulty maintaining dynamic balance, particularly during stair ascent and descent. Copyright © 2014 Elsevier B.V. All rights reserved.

A proposed measurement of optical orbital and spin angular momentum and its implications for photon angular momentum

NASA Astrophysics Data System (ADS)

Leader, Elliot

2018-04-01

The expression for the total angular momentum carried by a laser optical vortex beam, splits, in the paraxial approximation, into two terms which seem to represent orbital and spin angular momentum respectively. There are, however, two very different competing versions of the formula for the spin angular momentum, one based on the use of the Poynting vector, as in classical electrodynamics, the other related to the canonical expression for the angular momentum which occurs in Quantum Electrodynamics. I analyze the possibility that a sufficiently sensitive optical measurement could decide which of these corresponds to the actual physical angular momentum carried by the beam.

Infalling clouds on to supermassive black hole binaries - II. Binary evolution and the final parsec problem

NASA Astrophysics Data System (ADS)

Goicovic, Felipe G.; Sesana, Alberto; Cuadra, Jorge; Stasyszyn, Federico

2017-11-01

The formation of massive black hole binaries (MBHBs) is an unavoidable outcome of galaxy evolution via successive mergers. However, the mechanism that drives their orbital evolution from parsec separations down to the gravitational wave dominated regime is poorly understood, and their final fate is still unclear. If such binaries are embedded in gas-rich and turbulent environments, as observed in remnants of galaxy mergers, the interaction with gas clumps (such as molecular clouds) may efficiently drive their orbital evolution. Using numerical simulations, we test this hypothesis by studying the dynamical evolution of an equal mass, circular MBHB accreting infalling molecular clouds. We investigate different orbital configurations, modelling a total of 13 systems to explore different possible impact parameters and relative inclinations of the cloud-binary encounter. We focus our study on the prompt, transient phase during the first few orbits when the dynamical evolution of the binary is fastest, finding that this evolution is dominated by the exchange of angular momentum through gas capture by the individual black holes and accretion. Building on these results, we construct a simple model for evolving an MBHB interacting with a sequence of clouds, which are randomly drawn from reasonable populations with different levels of anisotropy in their angular momenta distributions. We show that the binary efficiently evolves down to the gravitational wave emission regime within a few hundred million years, overcoming the 'final parsec' problem regardless of the stellar distribution.

Neutron-star–black-hole binaries produced by binary-driven hypernovae

DOE PAGES

Fryer, Chris L.; Oliveira, F. G.; Rueda, Jorge A.; ...

2015-12-04

Here, binary-driven hypernovae (BdHNe) within the induced gravitational collapse paradigm have been introduced to explain energetic (E iso ≳10 52 erg), long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe). The progenitor is a tight binary composed of a carbon-oxygen (CO) core and a neutron-star (NS) companion, a subclass of the newly proposed “ultrastripped” binaries. The CO-NS short-period orbit causes the NS to accrete appreciable matter from the SN ejecta when the CO core collapses, ultimately causing it to collapse to a black hole (BH) and producing a GRB. These tight binaries evolve through the SN explosion very differentlymore » than compact binaries studied in population synthesis calculations. First, the hypercritical accretion onto the NS companion alters both the mass and the momentum of the binary. Second, because the explosion time scale is on par with the orbital period, the mass ejection cannot be assumed to be instantaneous. This dramatically affects the post-SN fate of the binary. Finally, the bow shock created as the accreting NS plows through the SN ejecta transfers angular momentum, braking the orbit. These systems remain bound even if a large fraction of the binary mass is lost in the explosion (well above the canonical 50% limit), and even large kicks are unlikely to unbind the system. Indeed, BdHNe produce a new family of NS-BH binaries unaccounted for in current population synthesis analyses and, although they may be rare, the fact that nearly 100% remain bound implies that they may play an important role in the compact merger rate, important for gravitational waves that, in turn, can produce a new class of ultrashort GRBs.« less

Neutron-Star-Black-Hole Binaries Produced by Binary-Driven Hypernovae.

PubMed

Fryer, Chris L; Oliveira, F G; Rueda, J A; Ruffini, R

2015-12-04

Binary-driven hypernovae (BdHNe) within the induced gravitational collapse paradigm have been introduced to explain energetic (E_{iso}≳10^{52}  erg), long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe). The progenitor is a tight binary composed of a carbon-oxygen (CO) core and a neutron-star (NS) companion, a subclass of the newly proposed "ultrastripped" binaries. The CO-NS short-period orbit causes the NS to accrete appreciable matter from the SN ejecta when the CO core collapses, ultimately causing it to collapse to a black hole (BH) and producing a GRB. These tight binaries evolve through the SN explosion very differently than compact binaries studied in population synthesis calculations. First, the hypercritical accretion onto the NS companion alters both the mass and the momentum of the binary. Second, because the explosion time scale is on par with the orbital period, the mass ejection cannot be assumed to be instantaneous. This dramatically affects the post-SN fate of the binary. Finally, the bow shock created as the accreting NS plows through the SN ejecta transfers angular momentum, braking the orbit. These systems remain bound even if a large fraction of the binary mass is lost in the explosion (well above the canonical 50% limit), and even large kicks are unlikely to unbind the system. Indeed, BdHNe produce a new family of NS-BH binaries unaccounted for in current population synthesis analyses and, although they may be rare, the fact that nearly 100% remain bound implies that they may play an important role in the compact merger rate, important for gravitational waves that, in turn, can produce a new class of ultrashort GRBs.

Neutron-Star-Black-Hole Binaries Produced by Binary-Driven Hypernovae

NASA Astrophysics Data System (ADS)

Fryer, Chris L.; Oliveira, F. G.; Rueda, J. A.; Ruffini, R.

2015-12-01

Binary-driven hypernovae (BdHNe) within the induced gravitational collapse paradigm have been introduced to explain energetic (Eiso≳1052 erg ), long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe). The progenitor is a tight binary composed of a carbon-oxygen (CO) core and a neutron-star (NS) companion, a subclass of the newly proposed "ultrastripped" binaries. The CO-NS short-period orbit causes the NS to accrete appreciable matter from the SN ejecta when the CO core collapses, ultimately causing it to collapse to a black hole (BH) and producing a GRB. These tight binaries evolve through the SN explosion very differently than compact binaries studied in population synthesis calculations. First, the hypercritical accretion onto the NS companion alters both the mass and the momentum of the binary. Second, because the explosion time scale is on par with the orbital period, the mass ejection cannot be assumed to be instantaneous. This dramatically affects the post-SN fate of the binary. Finally, the bow shock created as the accreting NS plows through the SN ejecta transfers angular momentum, braking the orbit. These systems remain bound even if a large fraction of the binary mass is lost in the explosion (well above the canonical 50% limit), and even large kicks are unlikely to unbind the system. Indeed, BdHNe produce a new family of NS-BH binaries unaccounted for in current population synthesis analyses and, although they may be rare, the fact that nearly 100% remain bound implies that they may play an important role in the compact merger rate, important for gravitational waves that, in turn, can produce a new class of ultrashort GRBs.

CONNECTING ANGULAR MOMENTUM AND GALACTIC DYNAMICS: THE COMPLEX INTERPLAY BETWEEN SPIN, MASS, AND MORPHOLOGY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teklu, Adelheid F.; Remus, Rhea-Silvia; Dolag, Klaus

The evolution and distribution of the angular momentum of dark matter (DM) halos have been discussed in several studies over the past decades. In particular, the idea arose that angular momentum conservation should allow us to infer the total angular momentum of the entire DM halo from measuring the angular momentum of the baryonic component, which is populating the center of the halo, especially for disk galaxies. To test this idea and to understand the connection between the angular momentum of the DM halo and its galaxy, we use a state-of-the-art, hydrodynamical cosmological simulation taken from the set of Magneticummore » Pathfinder simulations. Thanks to the inclusion of the relevant physical processes, the improved underlying numerical methods, and high spatial resolution, we successfully produce populations of spheroidal and disk galaxies self-consistently. Thus, we are able to study the dependence of galactic properties on their morphology. We find that (1) the specific angular momentum of stars in disk and spheroidal galaxies as a function of their stellar mass compares well with observational results; (2) the specific angular momentum of the stars in disk galaxies is slightly smaller compared to the specific angular momentum of the cold gas, in good agreement with observations; (3) simulations including the baryonic component show a dichotomy in the specific stellar angular momentum distribution when splitting the galaxies according to their morphological type (this dichotomy can also be seen in the spin parameter, where disk galaxies populate halos with slightly larger spin compared to spheroidal galaxies); (4) disk galaxies preferentially populate halos in which the angular momentum vector of the DM component in the central part shows a better alignment to the angular momentum vector of the entire halo; and (5) the specific angular momentum of the cold gas in disk galaxies is approximately 40% smaller than the specific angular momentum of the total DM halo and shows a significant scatter.« less

Optical angular momentum and atoms

PubMed Central

2017-01-01

Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom’s angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light’s OAM, aiding our fundamental understanding of light–matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069766

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clausen, Drew; Wade, Richard A.; Kopparapu, Ravi Kumar

Binaries that contain a hot subdwarf (sdB) star and a main-sequence companion may have interacted in the past. This binary population has historically helped determine our understanding of binary stellar evolution. We have computed a grid of binary population synthesis models using different assumptions about the minimum core mass for helium ignition, the envelope binding energy, the common-envelope ejection efficiency, the amount of mass and angular momentum lost during stable mass transfer, and the criteria for stable mass transfer on the red giant branch and in the Hertzsprung gap. These parameters separately and together can significantly change the entire predictedmore » population of sdBs. Nonetheless, several different parameter sets can reproduce the observed subpopulation of sdB + white dwarf and sdB + M dwarf binaries, which has been used to constrain these parameters in previous studies. The period distribution of sdB + early F dwarf binaries offers a better test of different mass transfer scenarios for stars that fill their Roche lobes on the red giant branch.« less

Disk-Anchored Magnetic Propellers - A Cure for the SW Sex Syndrome

NASA Astrophysics Data System (ADS)

Horne, Keith

In AE Aqr, magnetic fields transfer energy and angular momentum from a rapidly-spinning white dwarf to material in the gas stream from the companion star, with the effect of spinning down the white dwarf while flinging the gas stream material out of the binary system. This magnetic propeller produces a host of observable signatures, chief among which are broad, single-peaked, flaring emission lines with phase-shifted orbital kinematics. SW Sex stars have accretion disks, but also broad, single-peaked, phase-shifted emission lines similar to those seen in AE Aqr. We propose that a magnetic propeller similar to that which operates in AE Aqr is also at work in SW Sex stars - and to some extent in all nova-like systems. The propeller is anchored in the inner accretion disk, rather than, or in addition to, the white dwarf. Energy and angular momentum are thereby extracted from the inner disk and transferred to gas-stream material flowing above the disk, which is consequently pitched out of the system. This provides a non-local, dissipationless angular-momentum-extraction mechanism, which should result in cool inner disks with temperature profiles flatter than T propto R^{-3/4}, as observed in eclipse mapping studies of nova-like variables. The disk-anchored magnetic propeller model appears to explain qualitatively most if not all of the peculiar features of the SW Sex syndrome.

Puncture initial data for black-hole binaries with high spins and high boosts

NASA Astrophysics Data System (ADS)

Ruchlin, Ian; Healy, James; Lousto, Carlos O.; Zlochower, Yosef

2017-01-01

We solve the Hamiltonian and momentum constraints of general relativity for two black holes with nearly extremal spins and relativistic boosts in the puncture formalism. We use a non-conformally-flat ansatz with an attenuated superposition of two Lorentz-boosted, conformally Kerr or conformally Schwarzschild 3-metrics and their corresponding extrinsic curvatures. We compare evolutions of these data with the standard Bowen-York conformally flat ansatz (technically limited to intrinsic spins χ =S /MADM2=0.928 and boosts P /MADM=0.897 ), finding, typically, an order of magnitude smaller burst of spurious radiation and agreement with inspiral and merger. As a first case study, we evolve two equal-mass black holes from rest with an initial separation of d =12 M and spins χi=Si/mi2=0.99 , compute the waveforms produced by the collision, the energy and angular momentum radiated, and the recoil of the final remnant black hole. We find that the black-hole trajectories curve at close separations, leading to the radiation of angular momentum. We also study orbiting nonspinning and moderate-spin black-hole binaries and compare these with standard Bowen-York data. We find a substantial reduction in the nonphysical initial burst of radiation which leads to cleaner waveforms. Finally, we study the case of orbiting binary black-hole systems with spin magnitude χi=0.95 in an aligned configuration and compare waveform and final remnant results with those of the SXS Collaboration [54 A. H. Mroue et al., Phys. Rev. Lett. 111, 241104 (2013)., 10.1103/PhysRevLett.111.241104], finding excellent agreement. This represents the first moving puncture evolution of orbiting and spinning black holes exceeding the Bowen-York limit. Finally, we study different choices of the initial lapse and lapse evolution equation in the moving puncture approach to improve the accuracy and efficiency of the simulations.

Prediction of Lunar Reconnaissance Orbiter Reaction Wheel Assembly Angular Momentum Using Regression Analysis

NASA Technical Reports Server (NTRS)

DeHart, Russell

2017-01-01

This study determines the feasibility of creating a tool that can accurately predict Lunar Reconnaissance Orbiter (LRO) reaction wheel assembly (RWA) angular momentum, weeks or even months into the future. LRO is a three-axis stabilized spacecraft that was launched on June 18, 2009. While typically nadir-pointing, LRO conducts many types of slews to enable novel science collection. Momentum unloads have historically been performed approximately once every two weeks with the goal of maintaining system total angular momentum below 70 Nms; however flight experience shows the models developed before launch are overly conservative, with many momentum unloads being performed before system angular momentum surpasses 50 Nms. A more accurate model of RWA angular momentum growth would improve momentum unload scheduling and decrease the frequency of these unloads. Since some LRO instruments must be deactivated during momentum unloads and in the case of one instrument, decontaminated for 24 hours there after a decrease in the frequency of unloads increases science collection. This study develops a new model to predict LRO RWA angular momentum. Regression analysis of data from October 2014 to October 2015 was used to develop relationships between solar beta angle, slew specifications, and RWA angular momentum growth. The resulting model predicts RWA angular momentum using input solar beta angle and mission schedule data. This model was used to predict RWA angular momentum from October 2013 to October 2014. Predictions agree well with telemetry; of the 23 momentum unloads performed from October 2013 to October 2014, the mean and median magnitude of the RWA total angular momentum prediction error at the time of the momentum unloads were 3.7 and 2.7 Nms, respectively. The magnitude of the largest RWA total angular momentum prediction error was 10.6 Nms. Development of a tool that uses the models presented herein is currently underway.

Multiplicity At Early Stages Of Star Formation, Small Clusters. Observations Overview

NASA Astrophysics Data System (ADS)

Saito, Masao

2017-07-01

The SOLA (Soul of Lupus with ALMA) project is conducting comprehensive studies of the Lupus Molecular Clouds and their star formation processes covering 10-10^4 AU scale. Our goal is to exploit ALMA and other facilities over a wide wavelength range to establish a prototypical low-mass star forming scenario based on the Lupus region. In the presentation, we will focus on angular momentum in dense cores in a filament, molecular outflows from young stars, and Class 0/I binary survey in Lupus as well as overview of our projects. Our binary survey was conducted in ALMA cycle 2 and achieved at 0.2-0.3 arcsec resolution discovering new binary systems in Lupus. At the same time, we obtained EX Lup, EXor type burst source, data in ALMA Cycle 3.

Multiplicity at Early Stages of Star Formation, Small Clusters. Observations Overview

NASA Astrophysics Data System (ADS)

Saito, Masao

2017-06-01

The SOLA (Soul of Lupus with ALMA) project is conducting comprehensive studies of the Lupus Molecular Clouds and their star formation processes covering 10-10^4 AU scale. Our goal is to exploit ALMA and other facilities over a wide wavelength range to establish a prototypical low-mass star forming scenario based on the Lupus region. In the presentation, we will focus on angular momentum in dense cores in a filament, molecular outflows from young stars, and Class 0/I binary survey in Lupus as well as overview of our projects. Our binary survey was conducted in ALMA cycle 2 and achieved at 0.2-0.3 arcsec resolution discovering new binary systems in Lupus. At the same time, we obtained EX Lup, EXor type burst source, data in ALMA Cycle 3.

IUE spectrophotometry of the DA4 primary in the short-period white dwarf-red dwarf spectroscopic binary Case 1

NASA Technical Reports Server (NTRS)

Sion, E. M.; Guinan, E. F.; Wesemael, F.

1984-01-01

Low-resolution ultraviolet International Ultraviolet Explorer spectra of the DA white dwarf Case 1 are presented. The spectra show the presence of the 1400 A feature, already discovered in several other DA stars, and of a shallower trough in the 1550-1700 A range. A model atmosphere analysis of the ultraviolet energy distribution of the Ly-alpha red wing yields T(e) = 13,000 + or - 500 K. Possible interpretations of the 1400 A feature are reviewed. Case 1 is the coolest white dwarf found in a short-period, detached white dwarf-red dwarf binary, and its cooling time is consistent with estimates of the efficiency of angular momentum removal mechanisms in the phases subsequent to common envelope binary evolution.

Open cluster evolutions in binary system: How they dissolved

NASA Astrophysics Data System (ADS)

Priyatikanto, R.; Arifyanto, M. I.; Wulandari, H. R. T.

2014-03-01

Binarity among stellar clusters in galaxy is such a reality which has been realized for a long time, but still hides several questions and problems to be solved. Some of binary star clusters are formed by close encounter, but the others are formed together from similar womb. Some of them undergo separation process, while the others are in the middle of merger toward common future. The products of merger binary star cluster have typical characteristics which differ from solo clusters, especially in their spatial distribution and their stellar members kinematics. On the other hand, these merger products still have to face dissolving processes triggered by both internal and external factors. In this study, we performed N-body simulations of merger binary clusters with different initial conditions. After merging, these clusters dissolve with greater mass-loss rate because of their angular momentum. These rotating clusters also experience more deceleration caused by external tidal field.

Identification of trunk and pelvis movement compensations in patients with transtibial amputation using angular momentum separation.

PubMed

Gaffney, Brecca M; Murray, Amanda M; Christiansen, Cory L; Davidson, Bradley S

2016-03-01

Patients with unilateral dysvascular transtibial amputation (TTA) have a higher risk of developing low back pain than their healthy counterparts, which may be related to movement compensations used in the absence of ankle function. Assessing components of segmental angular momentum provides a unique framework to identify and interpret these movement compensations alongside traditional observational analyses. Angular momentum separation indicates two components of total angular momentum: (1) transfer momentum and (2) rotational momentum. The objective of this investigation was to assess movement compensations in patients with dysvascular TTA, patients with diabetes mellitus (DM), and healthy controls (HC) by examining patterns of generating and arresting trunk and pelvis segmental angular momenta during gait. We hypothesized that all groups would demonstrate similar patterns of generating/arresting total momentum and transfer momentum in the trunk and pelvis in reference to the groups (patients with DM and HC). We also hypothesized that patients with amputation would demonstrate different (larger) patterns of generating/arresting rotational angular momentum in the trunk. Patients with amputation demonstrated differences in trunk and pelvis transfer angular momentum in the sagittal and transverse planes in comparison to the reference groups, which indicates postural compensations adopted during walking. However, patients with amputation demonstrated larger patterns of generating and arresting of trunk and pelvis rotational angular momentum in comparison to the reference groups. These segmental rotational angular momentum patterns correspond with high eccentric muscle demands needed to arrest the angular momentum, and may lead to consequential long-term effects such as low back pain. Copyright © 2016 Elsevier B.V. All rights reserved.

Spin-to-orbit conversion at acousto-optic diffraction of light: conservation of optical angular momentum.

PubMed

Skab, Ihor; Vlokh, Rostyslav

2012-04-01

Acousto-optic diffraction of light in optically active cubic crystals is analyzed from the viewpoint of conservation of optical angular momentum. It is shown that the availability of angular momentum in the diffracted optical beam can be necessarily inferred from the requirements of angular momentum conservation law. As follows from our analysis, a circularly polarized diffracted wave should bear an orbital angular momentum. The efficiency of the spin-to-orbit momentum conversion is governed by the efficiency of acousto-optic diffraction.

Generation of vertical angular momentum in single, double, and triple-turn pirouette en dehors in ballet.

PubMed

Kim, Jemin; Wilson, Margaret A; Singhal, Kunal; Gamblin, Sarah; Suh, Cha-Young; Kwon, Young-Hoo

2014-09-01

The purpose of this study was to investigate the vertical angular momentum generation strategies used by skilled ballet dancers in pirouette en dehors. Select kinematic parameters of the pirouette preparation (stance depth, vertical center-of-mass motion range, initial shoulder line position, shoulder line angular displacement, and maximum trunk twist angle) along with vertical angular momentum parameters during the turn (maximum momentums of the whole body and body parts, and duration and rate of generation) were obtained from nine skilled collegiate ballet dancers through a three-dimensional motion analysis and compared among three turn conditions (single, double, and triple). A one-way ('turn') multivariate analysis of variance of the kinematic parameters and angular momentum parameters of the whole body and a two-way analysis of variance ('turn' × 'body') of the maximum angular momentums of the body parts were conducted. Significant 'turn' effects were observed in the kinematic/angular momentum parameters (both the preparation and the turn) (p <  0.05). As the number of turns increased, skilled dancers generated larger vertical angular momentums by predominantly increasing the rate of momentum generation using rotation of the upper trunk and arms. The trail (closing) arm showed the largest contribution to whole-body angular momentum followed by the lead arm.

Universal relations for differentially rotating relativistic stars at the threshold to collapse

NASA Astrophysics Data System (ADS)

Bozzola, Gabriele; Stergioulas, Nikolaos; Bauswein, Andreas

2018-03-01

A binary neutron star merger produces a rapidly and differentially rotating compact remnant whose lifespan heavily affects the electromagnetic and gravitational emissions. Its stability depends on both the equation of state (EOS) and the rotation law and it is usually investigated through numerical simulations. Nevertheless, by means of a sufficient criterion for secular instability, equilibrium sequences can be used as a computational inexpensive way to estimate the onset of dynamical instability, which, in general, is close to the secular one. This method works well for uniform rotation and relies on the location of turning points: stellar models that are stationary points in a sequence of equilibrium solutions with constant rest mass or angular momentum. Here, we investigate differentially rotating models (using a large number of EOSs and different rotation laws) and find that several universal relations between properly scaled gravitational mass, rest mass and angular momentum of the turning-point models that are valid for uniform rotation are insensitive to the degree of differential rotation, to high accuracy.

Spectral and spatial imaging of the Be+sdO binary ϕ Persei

NASA Astrophysics Data System (ADS)

Mourard, D.; Monnier, J. D.; Meilland, A.; Gies, D.; Millour, F.; Benisty, M.; Che, X.; Grundstrom, E. D.; Ligi, R.; Schaefer, G.; Baron, F.; Kraus, S.; Zhao, M.; Pedretti, E.; Berio, P.; Clausse, J. M.; Nardetto, N.; Perraut, K.; Spang, A.; Stee, P.; Tallon-Bosc, I.; McAlister, H.; ten Brummelaar, T.; Ridgway, S. T.; Sturmann, J.; Sturmann, L.; Turner, N.; Farrington, C.

2015-05-01

Aims: The rapidly rotating Be star ϕ Persei was spun up by mass and angular momentum transfer from a now stripped-down, hot subdwarf companion. Here we present the first high angular resolution images of ϕ Persei made possible by new capabilities in long-baseline interferometry at near-IR and visible wavelengths. We analyzed these images to search for the companion, to determine the binary orbit, stellar masses, and fluxes, and to examine the geometrical and kinematical properties of the outflowing disk surrounding the Be star. Methods: We observed ϕ Persei with the MIRC and VEGA instruments of the CHARA Array. MIRC was operated in six-telescope mode, whereas VEGA was configured in four-telescope mode with a change of quadruplets of telescopes during two nights to improve the (u,v) plane coverage. Additional MIRC-only observations were performed to track the orbital motion of the companion, and these were fit together with new and existing radial velocity measurements of both stars to derive the complete orbital elements and distance. We also used the MIRC data to reconstruct an image of the Be disk in the near-IR H-band. VEGA visible broadband and spectro-interferometric Hα observations were fit with analytical models for the Be star and disk, and image reconstruction was performed on the spectrally resolved Hα emission line data. Results: The hot subdwarf companion is clearly detected in the near-IR data at each epoch of observation with a flux contribution of 1.5% in the H band, and restricted fits indicate that its flux contribution rises to 3.3% in the visible. A new binary orbital solution is determined by combining the astrometric and radial velocity measurements. The derived stellar masses are 9.6 ± 0.3 M⊙ and 1.2 ± 0.2 M⊙ for the Be primary and subdwarf secondary, respectively. The inferred distance (186 ± 3 pc), kinematical properties, and evolutionary state are consistent with membership of ϕ Persei in the α Per cluster. From the cluster age we deduce significant constraints on the initial masses and evolutionary mass transfer processes that transformed the ϕ Persei binary system. The interferometric data place strong constraints on the Be disk elongation, orientation, and kinematics, and the disk angular momentum vector is coaligned with and has the same sense of rotation as the orbital angular momentum vector. The VEGA visible continuum data indicate an elongated shape for the Be star itself, due to the combined effects of rapid rotation, partial obscuration of the photosphere by the circumstellar disk, and flux from the bright inner disk. Based on observations with MIRC-6T and VEGA-4T instruments on the CHARA Array.Table 2 and Appendix A are available in electronic form at http://www.aanda.org

CLOSE BINARIES WITH INFRARED EXCESS: DESTROYERS OF WORLDS?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matranga, M.; Drake, J. J.; Kashyap, V. L.

2010-09-10

We present the results of a Spitzer photometric investigation into the IR excesses of close binary systems. In a sample of 10 objects, excesses in Infrared Array Camera and MIPS24 bands implying the presence of warm dust are found for 3. For two objects, we do not find excesses reported in earlier IRAS studies. We discuss the results in the context of the scenario suggested by Rhee and co-workers, in which warm dust is continuously created by destructive collisions between planetary bodies. A simple numerical model for the steady-state distribution of dust in one IR excess system shows a centralmore » clearing of radius 0.22 AU caused by dynamical perturbations from the binary star. This is consistent with the size of the central clearing derived from the Spitzer spectral energy distribution. We conclude that close binaries could be efficient 'destroyers of worlds' and lead to destabilization of the orbits of their planetary progeny by magnetically driven angular momentum loss and secular shrinkage of the binary separation.« less

Estimating gravitational radiation from super-emitting compact binary systems

NASA Astrophysics Data System (ADS)

Hanna, Chad; Johnson, Matthew C.; Lehner, Luis

2017-06-01

Binary black hole mergers are among the most violent events in the Universe, leading to extreme warping of spacetime and copious emission of gravitational radiation. Even though black holes are the most compact objects they are not necessarily the most efficient emitters of gravitational radiation in binary systems. The final black hole resulting from a binary black hole merger retains a significant fraction of the premerger orbital energy and angular momentum. A nonvacuum system can in principle shed more of this energy than a black hole merger of equivalent mass. We study these super-emitters through a toy model that accounts for the possibility that the merger creates a compact object that retains a long-lived time-varying quadrupole moment. This toy model may capture the merger of (low mass) neutron stars, but it may also be used to consider more exotic compact binaries. We hope that this toy model can serve as a guide to more rigorous numerical investigations into these systems.

Flip-flopping binary black holes.

PubMed

Lousto, Carlos O; Healy, James

2015-04-10

We study binary spinning black holes to display the long term individual spin dynamics. We perform a full numerical simulation starting at an initial proper separation of d≈25M between equal mass holes and evolve them down to merger for nearly 48 orbits, 3 precession cycles, and half of a flip-flop cycle. The simulation lasts for t=20 000M and displays a total change in the orientation of the spin of one of the black holes from an initial alignment with the orbital angular momentum to a complete antialignment after half of a flip-flop cycle. We compare this evolution with an integration of the 3.5 post-Newtonian equations of motion and spin evolution to show that this process continuously flip flops the spin during the lifetime of the binary until merger. We also provide lower order analytic expressions for the maximum flip-flop angle and frequency. We discuss the effects this dynamics may have on spin growth in accreting binaries and on the observational consequences for galactic and supermassive binary black holes.

Twisted molecular excitons as mediators for changing the angular momentum of light

NASA Astrophysics Data System (ADS)

Zang, Xiaoning; Lusk, Mark T.

2017-07-01

Molecules with CN or CN h symmetry can absorb quanta of optical angular momentum to generate twisted excitons with well-defined quasiangular momenta of their own. Angular momentum is conserved in such interactions at the level of a paraxial approximation for the light beam. A sequence of absorption events can thus be used to create a range of excitonic angular momenta. Subsequent decay can produce radiation with a single angular momentum equal to that accumulated. Such molecules can thus be viewed as mediators for changing the angular momentum of light. This sidesteps the need to exploit nonlinear light-matter interactions based on higher-order susceptibilities. A tight-binding paradigm is used to verify angular momentum conservation and demonstrate how it can be exploited to change the angular momentum of light. The approach is then extended to a time-dependent density functional theory setting where the key results are shown to hold in a many-body, multilevel setting.

Efficiency of ETV diagrams as diagnostic tools for long-term period variations. II. Non-conservative mass transfer, and gravitational radiation

NASA Astrophysics Data System (ADS)

Nanouris, N.; Kalimeris, A.; Antonopoulou, E.; Rovithis-Livaniou, H.

2015-03-01

Context. The credibility of an eclipse timing variation (ETV) diagram analysis is investigated for various manifestations of the mass transfer and gravitational radiation processes in binary systems. The monotonicity of the period variations and the morphology of the respective ETV diagrams are thoroughly explored in both the direct impact and the accretion disk mode of mass transfer, accompanied by different types of mass and angular momentum losses (through a hot-spot emission from the gainer and via the L2/L3 points). Aims: Our primary objective concerns the traceability of each physical mechanism by means of an ETV diagram analysis. Also, possible critical mass ratio values are sought for those transfer modes that involve orbital angular momentum losses strong enough to dictate the secular period changes even when highly competitive mechanisms with the opposite direction act simultaneously. Methods: The dot{J-dot{P}} relation that governs the orbital evolution of a binary system is set to provide the exact solution for the period and the function expected to represent the subsequent eclipse timing variations. The angular momentum transport is parameterized through appropriate empirical relations, which are inferred from semi-analytical ballistic models. Then, we numerically determine the minimum temporal range over which a particular mechanism is rendered measurable, as well as the critical mass ratio values that signify monotonicity inversion in the period modulations. Results: Mass transfer rates comparable to or greater than 10-8 M⊙ yr-1 are measurable for typical noise levels of the ETV diagrams, regardless of whether the process is conservative. However, the presence of a transient disk around the more massive component defines a critical mass ratio (qcr ≈ 0.83) above which the period turns out to decrease when still in the conservative regime, rendering the measurability of the anticipated variations a much more complicated task. The effects of gravitational radiation proved to be rather undetectable, except for systems with physical characteristics that only refer to cataclysmic variables. Conclusions: The monotonicity of the period variations and the curvature of the respective ETV diagrams depend strongly on the accretion mode and the degree of conservatism of the transfer process. Unlike the hot-spot effects, the Lagrangian points L2 and L3 support very efficient routes of strong angular momentum loss. It is further shown that escape of mass via the L3 point - when the donor is the less massive component - safely provides critical mass ratios above which the period is expected to decrease, no matter how intense the process is.

Massive star formation by accretion. II. Rotation: how to circumvent the angular momentum barrier?

NASA Astrophysics Data System (ADS)

Haemmerlé, L.; Eggenberger, P.; Meynet, G.; Maeder, A.; Charbonnel, C.; Klessen, R. S.

2017-06-01

Context. Rotation plays a key role in the star-formation process, from pre-stellar cores to pre-main-sequence (PMS) objects. Understanding the formation of massive stars requires taking into account the accretion of angular momentum during their PMS phase. Aims: We study the PMS evolution of objects destined to become massive stars by accretion, focusing on the links between the physical conditions of the environment and the rotational properties of young stars. In particular, we look at the physical conditions that allow the production of massive stars by accretion. Methods: We present PMS models computed with a new version of the Geneva Stellar Evolution code self-consistently including accretion and rotation according to various accretion scenarios for mass and angular momentum. We describe the internal distribution of angular momentum in PMS stars accreting at high rates and we show how the various physical conditions impact their internal structures, evolutionary tracks, and rotation velocities during the PMS and the early main sequence. Results: We find that the smooth angular momentum accretion considered in previous studies leads to an angular momentum barrier and does not allow the formation of massive stars by accretion. A braking mechanism is needed in order to circumvent this angular momentum barrier. This mechanism has to be efficient enough to remove more than two thirds of the angular momentum from the inner accretion disc. Due to the weak efficiency of angular momentum transport by shear instability and meridional circulation during the accretion phase, the internal rotation profiles of accreting stars reflect essentially the angular momentum accretion history. As a consequence, careful choice of the angular momentum accretion history allows circumvention of any limitation in mass and velocity, and production of stars of any mass and velocity compatible with structure equations.

Evolutionary orbital period change in BH Virginis

NASA Astrophysics Data System (ADS)

Gebrehiwot, Y. M.; Tessema, S. B.; Berdnikov, L. N.

2017-04-01

The study of orbital period change of close binaries, such as BH Virginis (BH Vir), using very long time baseline is vital to understand evolutionary processes of the system. In this paper, we use photometric data to analyze the evolutionary orbital period change of the short period RS CVn-type binary system, BH Vir, with a time baseline spanning 123 years. We used the software version of the Hertzsprung method to describe the O-C curve of the system, and we found that the orbital period secularly decreases at a rate of dp/dt=-(0.0013000 ± 0.0000863) s yr^{-1}. Because BH Vir is a typical detached binary system and both components are late type (G0 V + G2 V) stars, the evolutionary period change could be caused by the angular momentum loss due to tides coupled with magnetic breaking.

Stellar Rotation on the Main Sequence

NASA Astrophysics Data System (ADS)

Soderblom, D.; Murdin, P.

2000-11-01

The conservation of ANGULAR MOMENTUM is the one effective counterbalance to the inexorable pull of gravity in the universe, and so everything rotates. Stars acquire their angular momentum when they form, and, indeed, the manner in which nearly all this initial angular momentum is dissipated remains poorly understood, but without substantial angular momentum loss an interstellar cloud could never ...

There are many ways to spin a photon: Half-quantization of a total optical angular momentum

PubMed Central

Ballantine, Kyle E.; Donegan, John F.; Eastham, Paul R.

2016-01-01

The angular momentum of light plays an important role in many areas, from optical trapping to quantum information. In the usual three-dimensional setting, the angular momentum quantum numbers of the photon are integers, in units of the Planck constant ħ. We show that, in reduced dimensions, photons can have a half-integer total angular momentum. We identify a new form of total angular momentum, carried by beams of light, comprising an unequal mixture of spin and orbital contributions. We demonstrate the half-integer quantization of this total angular momentum using noise measurements. We conclude that for light, as is known for electrons, reduced dimensionality allows new forms of quantization. PMID:28861467

Physical angular momentum separation for QED

NASA Astrophysics Data System (ADS)

Sun, Weimin

2017-04-01

We study the non-uniqueness problem of the gauge-invariant angular momentum separation for the case of QED, which stems from the recent controversy concerning the proper definitions of the orbital angular momentum and spin operator of the individual parts of a gauge field system. For the free quantum electrodynamics without matter, we show that the basic requirement of Euclidean symmetry selects a unique physical angular momentum separation scheme from the multitude of the possible angular momentum separation schemes constructed using the various gauge-invariant extensions (GIEs). Based on these results, we propose a set of natural angular momentum separation schemes for the case of interacting QED by invoking the formalism of asymptotic fields. Some perspectives on such a problem for the case of QCD are briefly discussed.

Angular momentum of dwarf galaxies

NASA Astrophysics Data System (ADS)

Kurapati, Sushma; Chengalur, Jayaram N.; Pustilnik, Simon; Kamphuis, Peter

2018-05-01

Mass and specific angular momentum are two fundamental physical parameters of galaxies. We present measurements of the baryonic mass and specific angular momentum of 11 void dwarf galaxies derived from neutral hydrogen (HI) synthesis data. Rotation curves were measured using 3D and 2D tilted ring fitting routines, and the derived curves generally overlap within the error bars, except in the central regions where, as expected, the 3D routines give steeper curves. The specific angular momentum of void dwarfs is found to be high compared to an extrapolation of the trends seen for higher mass bulge-less spirals, but comparable to that of other dwarf irregular galaxies that lie outside of voids. As such, our data show no evidence for a dependence of the specific angular momentum on the large scale environment. Combining our data with the data from the literature, we find a baryonic threshold of ˜109.1 M⊙ for this increase in specific angular momentum. Interestingly, this threshold is very similar to the mass threshold below which the galaxy discs start to become systematically thicker. This provides qualitative support to the suggestion that the thickening of the discs, as well as the increase in specific angular momentum, are both results of a common physical mechanism, such as feedback from star formation. Quantitatively, however, the amount of star formation observed in our dwarfs appears insufficient to produce the observed increase in specific angular momentum. It is hence likely that other processes, such as cold accretion of high angular momentum gas, also play a role in increasing the specific angular momentum.

Optical Flares and a Long-lived Dark Spot on a Cool Shallow Contact Binary

NASA Astrophysics Data System (ADS)

Qian, S.-B.; Wang, J.-J.; Zhu, L.-Y.; Snoonthornthum, B.; Wang, L.-Z.; Zhao, E. G.; Zhou, X.; Liao, W.-P.; Liu, N.-P.

2014-05-01

W UMa-type stars are contact systems where both cool components fill the critical Roche lobes and share a common convective envelope. Long and unbroken time-series photometry is expected to play an important role in their origin and activity. The newly discovered short-period W UMa-type star, CSTAR 038663, was monitored continuously by Chinese Small Telescope ARray (CSTAR) in Antarctica during the winters of 2008 and 2010. There were 15 optical flares recorded in the i band during the winter of 2010. This was the first time such flares were detected from a W UMa-type star. By analyzing the nearly unbroken photometric data from 2008, it is discovered that CSTAR 038663 is a W-type shallow contact binary system (f = 10.6(± 2.9)%) with a high mass ratio of q = 1.12(± 0.01), where the less massive component is slightly hotter than the more massive one. The asymmetric light curves are explained by the presence of a dark spot on the more massive component. Its temperature is about 800 K lower than the stellar photosphere and it covers 2.1% of the total photospheric surface. The lifetime of the dark spot is longer than 116 days. Using 725 eclipse times, we found that the observed-calculated (O-C) curve may show a cyclic variation that is explained by the presence of a close-in third body. Both the shallow contact configuration and the extremely high mass ratio suggest that CSTAR 038663 is presently evolving into a contact system with little mass transfer. The formation and evolution is driven by the loss of angular momentum via magnetic braking, and the close-in companion star is expected to play an important role, removing angular momentum from the central eclipsing binary.

The first mass and angular momentum loss measurements for a CV-like binary

NASA Astrophysics Data System (ADS)

Drake, Jeremy

2015-10-01

The period distribution of close binaries, cataclysmic variables, novae and single-degenerate SN1a progenitor candidates is largely controlled by magnetically-driven mass and angular momentum loss (AML) from the M dwarf secondary. The mass loss rates for these spun-up stars remain essentially unknown and impossible to observe directly, with likely values in the range 1e-12 to 1e-15 Msun/yr. AML presciptions for CVs differ by orders of magnitude. One way to measure the mass loss rate is to observe the dM wind accrete onto its WD companion in a pre-CV very close to Roche Lobe overflow but lacking the obscuring complications and emission from an accretion disk. The measurement can be combined with realistic MHD models to understand the accretion fraction, the mass that escapes, and the AML. The best-studied nearby pre-CV is QS Vir (48pc, P=3.6hr). However, its wind accretion rates measured from 1999 HST UV spectra of the WD metal absorption lines and 2006 XMM-Newton CCD spectroscopy differ by a factor of a thousand, pointing to either a dominant CME stochastic component, or a magnetic switch found in MHD simulations and driven by cyclic activity on the M dwarf. HST COS spectra combined with XMM-Newton monitoring on timescales from weeks to years will tease out CME vs cyclic accretion variations. UV and X-ray measurements will provide the first consistency check of both accretion rate measurement methods. MHD models tailored to the system will enable the first quasi-direct measurements of the mass loss and AML from a CV-like binary. Our project requires 6 HST/COS orbits in Cycles 22-24, and 60ksec on XMM in Cycle 22

The first mass and angular momentum loss measurements for a CV-like binary

NASA Astrophysics Data System (ADS)

Drake, Jeremy

2014-10-01

The period distribution of close binaries, cataclysmic variables, novae and single-degenerate SN1a progenitor candidates is largely controlled by magnetically-driven mass and angular momentum loss (AML) from the M dwarf secondary. The mass loss rates for these spun-up stars remain essentially unknown and impossible to observe directly, with likely values in the range 1e-12 to 1e-15 Msun/yr. AML presciptions for CVs differ by orders of magnitude. One way to measure the mass loss rate is to observe the dM wind accrete onto its WD companion in a pre-CV very close to Roche Lobe overflow but lacking the obscuring complications and emission from an accretion disk. The measurement can be combined with realistic MHD models to understand the accretion fraction, the mass that escapes, and the AML. The best-studied nearby pre-CV is QS Vir (48pc, P=3.6hr). However, its wind accretion rates measured from 1999 HST UV spectra of the WD metal absorption lines and 2006 XMM-Newton CCD spectroscopy differ by a factor of a thousand, pointing to either a dominant CME stochastic component, or a "magnetic switch" found in MHD simulations and driven by cyclic activity on the M dwarf. HST COS spectra combined with XMM-Newton monitoring on timescales from weeks to years will tease out CME vs cyclic accretion variations. UV and X-ray measurements will provide the first consistency check of both accretion rate measurement methods. MHD models tailored to the system will enable the first quasi-direct measurements of the mass loss and AML from a CV-like binary. Our project requires 6 HST/COS orbits in Cycles 22-24, and 60ksec on XMM in Cycle 22

The first mass and angular momentum loss measurements for a CV-like binary

NASA Astrophysics Data System (ADS)

Drake, Jeremy

2016-10-01

The period distribution of close binaries, cataclysmic variables, novae and single-degenerate SN1a progenitor candidates is largely controlled by magnetically-driven mass and angular momentum loss (AML) from the M dwarf secondary. The mass loss rates for these spun-up stars remain essentially unknown and impossible to observe directly, with likely values in the range 1e-12 to 1e-15 Msun/yr. AML presciptions for CVs differ by orders of magnitude. One way to measure the mass loss rate is to observe the dM wind accrete onto its WD companion in a pre-CV very close to Roche Lobe overflow but lacking the obscuring complications and emission from an accretion disk. The measurement can be combined with realistic MHD models to understand the accretion fraction, the mass that escapes, and the AML. The best-studied nearby pre-CV is QS Vir (48pc, P=3.6hr). However, its wind accretion rates measured from 1999 HST UV spectra of the WD metal absorption lines and 2006 XMM-Newton CCD spectroscopy differ by a factor of a thousand, pointing to either a dominant CME stochastic component, or a magnetic switch found in MHD simulations and driven by cyclic activity on the M dwarf. HST COS spectra combined with XMM-Newton monitoring on timescales from weeks to years will tease out CME vs cyclic accretion variations. UV and X-ray measurements will provide the first consistency check of both accretion rate measurement methods. MHD models tailored to the system will enable the first quasi-direct measurements of the mass loss and AML from a CV-like binary. Our project requires 6 HST/COS orbits in Cycles 22-24, and 60ksec on XMM in Cycle 22

Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.

Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that ismore » capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.« less

Analysis of the geodetic residuals as differences between geodetic and sum of the atmospheric and ocean excitation of polar motion

NASA Astrophysics Data System (ADS)

Kolaczek, B.; Pasnicka, M.; Nastula, J.

2012-12-01

Up to now studies of geophysical excitation of polar motion containing AAM (Atmospheric Angular Momentum), OAM (Oceanic Angular Momentum) and HAM (Hydrological Angular Momentum) excitation functions of polar motion have not achieved the total agreement between geophysical and determined geodetic excitation (GAM, Geodetic AngularMomentum) functions of polar motion...

A New Photometric Investigation of the W UMa-Type Binary BI CVn

NASA Astrophysics Data System (ADS)

Qian, S.-B.; He, J.-J.; Liu, L.; Zhu, L.-Y.; Liao, W. P.

2008-12-01

New photometric observations and their investigation of the W UMa-type binary, BI CVn, are presented. The variations of the orbital period were analyzed based on 12 new determined times of light minimum together with the others compiled from the literature. It is discovered that the period of BI CVn shows a long-term period decrease at a rate of \\dot{P}=-1.51(± 0.12)× {10^{-7}} days year-1 while it undergoes a cyclic variation with a period of 27.0 years and an amplitude of 0fd0151. Photometric solutions determined with the Wilson-Devinney method suggest that BI CVn is a contact binary with a degree of contact of 18.0(±1.7)%. The asymmetry of the light curves was interpreted by the presence of dark spots on both components, and absolute parameters were determined by combining the photometric elements with the spectroscopic solutions given by Lu. The observed period decrease can be plausibly explained by a combination of the mass transfer from the primary to the secondary and angular momentum loss via magnetic braking. The cyclic period oscillation suggests that BI CVn is a triple system containing a tertiary component with a mass no less than 0.58 M sun in a 27.0 year orbit. As in the cases of the other contact binaries (e.g., AH Cnc, AP Leo, AD Cnc, and UX Eri), it is possible that this tertiary companion played an important role for the formation and evolution of the contact system by removing angular momentum from the central system via Kozai oscillation or a combination of Kozai cycle and tidal friction, which causes the eclipsing pair to have a short initial orbital period (e.g., P < 5d). In that case, can the initially detached system evolve into the present contact configuration via a combination of magnetic torques from stellar winds and a case A mass transfer?

Yet Another Model for the Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Leonard, P. J. T.

2000-05-01

We consider whether a gamma-ray burst can result from a merger between a neutron star and a massive main-sequence star in a binary system following a supernova explosion. The scenario for how this can happen is outlined in Leonard, Hills & Dewey 1994, ApJ, 423, L19-L22. The initially more massive star in a massive binary system evolves and undergoes core collapse to produce a neutron star and supernova. Since the outer layers of the originally more massive star have been transferred to the other star, then the supernova may be hydrogen deficient. The newly-formed neutron star receives a random kick during the explosion. In a small fraction of the cases, the kick has the appropriate direction and amplitude to remove most of the orbital angular momentum of the post-supernova binary system. The result is an orbit with a pericenter smaller than the radius of the non-exploding star. The neutron star rather quickly becomes embedded in the other star, and sinks to its center, giving the envelope of the merged object a lot of rotational angular momentum in the process. Leonard, Hills & Dewey estimate the rate of this process in the Galaxy to be 0.06 per square kpc per Myr for secondaries more massive than 15 solar masses. The fate of the merged object has been the source of much speculation, and we shall assume that a collapsar-like scenario results. That is, the neutron star experiences runaway accretion, collapses into a black hole, which continues to accrete, and produces a pair of jets that bore their way out of the merged object. Observers who lie in the direction of either jet will see a gamma-ray burst. Roughly 1% of supernovae in massive binary systems result in neutron stars quickly becoming embedded in the secondaries, and of those which produce black holes, only 1% would be observable as gamma-ray bursts, if the jets are beamed into 1% of the sky.

Dynamo magnetic field-induced angular momentum transport in protostellar nebulae - The 'minimum mass' protosolar nebula

NASA Technical Reports Server (NTRS)

Stepinski, T. F.; Levy, E. H.

1990-01-01

Magnetic torques can produce angular momentum redistribution in protostellar nebulas. Dynamo magnetic fields can be generated in differentially rotating and turbulent nebulas and can be the source of magnetic torques that transfer angular momentum from a protostar to a disk, as well as redistribute angular momentum within a disk. A magnetic field strength of 100-1000 G is needed to transport the major part of a protostar's angular momentum into a surrounding disk in a time characteristic of star formation, thus allowing formation of a solar-system size protoplanetary nebula in the usual 'minimum-mass' model of the protosolar nebula. This paper examines the possibility that a dynamo magnetic field could have induced the needed angular momentum transport from the proto-Sun to the protoplanetary nebula.

Estimating energy-momentum and angular momentum near null infinity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Helfer, Adam D.

2010-04-15

The energy-momentum and angular momentum contained in a spacelike two-surface of spherical topology are estimated by joining the two-surface to null infinity via an approximate no-incoming-radiation condition. The result is a set of gauge-invariant formulas for energy-momentum and angular momentum which should be applicable to much numerical work; it also gives estimates of the finite-size effects.

SuperWASP J015100.23-100524.2: A SPOTTED SHALLOW-CONTACT BINARY BELOW THE PERIOD LIMIT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, S. B.; Zhang, B.; He, J. J.

2015-10-15

SuperWASP J015100.23-100524.2 (hereafter J015100) is an eclipsing binary with an orbital period of 0.d2145 that is below the short-period limit of contact binary stars. Complete light curves of J015100 in B, V, R, and I bands are presented and are analyzed with the Wilson–Devinney method. It has been discovered that J015100 is a shallow-contact binary (f = 14.6(±2.7)%) with a mass ratio of 3.128. It is a W-type contact binary where the less massive component is about 130 K hotter than the more massive one. The asymmetries of light curves are explained as one dark spot on the more massivemore » component. The detection of J015100 as a contact binary below the period limit suggests that contact binaries below this limit are not rapidly destroyed. This shallow-contact system may be formed from a detached short-period binary similar to DV Psc (Sp. = K4/K5; P = 0.d30855) via orbital shrinkage due to angular momentum loss through magnetic stellar wind.« less

Effects of Wall-Normal and Angular Momentum Injections in Airfoil Separation Control

NASA Astrophysics Data System (ADS)

Munday, Phillip M.; Taira, Kunihiko

2018-05-01

The objective of this computational study is to quantify the influence of wall-normal and angular momentum injections in suppressing laminar flow separation over a canonical airfoil. Open-loop control of fully separated, incompressible flow over a NACA 0012 airfoil at $\\alpha = 9^\\circ$ and $Re = 23,000$ is examined with large-eddy simulations. This study independently introduces wall-normal momentum and angular momentum into the separated flow using swirling jets through model boundary conditions. The response of the flow field and the surface vorticity fluxes to various combinations of actuation inputs are examined in detail. It is observed that the addition of angular momentum input to wall-normal momentum injection enhances the suppression of flow separation. Lift enhancement and suppression of separation with the wall-normal and angular momentum inputs are characterized by modifying the standard definition of the coefficient of momentum. The effect of angular momentum is incorporated into the modified coefficient of momentum by introducing a characteristic swirling jet velocity based on the non-dimensional swirl number. With this single modified coefficient of momentum, we are able to categorize each controlled flow into separated, transitional, and attached flows.

A Computational Technique to Determine the Angular Displacement, Velocity and Momentum of a Human Body.

ERIC Educational Resources Information Center

Hay, James G.; Wilson, Barry D.

The angular momentum of a human body derived from both the angular velocity and angular displacement, utilizing cinematographic records has not been adequately assessed, prior to this study. Miller (1970) obtained the angular momentum but only during the airborne phase of activity. The method used by Ramey (1973) involved a force platform, but…

GALACTIC ANGULAR MOMENTUM IN THE ILLUSTRIS SIMULATION: FEEDBACK AND THE HUBBLE SEQUENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genel, Shy; Fall, S. Michael; Snyder, Gregory F.

We study the stellar angular momentum of thousands of galaxies in the Illustris cosmological simulation, which captures gravitational and gas dynamics within galaxies, as well as feedback from stars and black holes. We find that the angular momentum of the simulated galaxies matches observations well, and in particular two distinct relations are found for late-type versus early-type galaxies. The relation for late-type galaxies corresponds to the value expected from full conservation of the specific angular momentum generated by cosmological tidal torques. The relation for early-type galaxies corresponds to retention of only ∼30% of that, but we find that those early-typemore » galaxies with low angular momentum at z = 0 nevertheless reside at high redshift on the late-type relation. Some of them abruptly lose angular momentum during major mergers. To gain further insight, we explore the scaling relations in simulations where the galaxy formation physics is modified with respect to the fiducial model. We find that galactic winds with high mass-loading factors are essential for obtaining the high angular momentum relation typical for late-type galaxies, while active galactic nucleus feedback largely operates in the opposite direction. Hence, feedback controls the stellar angular momentum of galaxies, and appears to be instrumental for establishing the Hubble sequence.« less

Analysis of angular momentum properties of photons emitted in fundamental atomic processes

NASA Astrophysics Data System (ADS)

Zaytsev, V. A.; Surzhykov, A. S.; Shabaev, V. M.; Stöhlker, Th.

2018-04-01

Many atomic processes result in the emission of photons. Analysis of the properties of emitted photons, such as energy and angular distribution as well as polarization, is regarded as a powerful tool for gaining more insight into the physics of corresponding processes. Another characteristic of light is the projection of its angular momentum upon propagation direction. This property has attracted a special attention over the past decades due to studies of twisted (or vortex) light beams. Measurements being sensitive to this projection may provide valuable information about the role of angular momentum in the fundamental atomic processes. Here we describe a simple theoretical method for determination of the angular momentum properties of the photons emitted in various atomic processes. This method is based on the evaluation of expectation value of the total angular momentum projection operator. To illustrate the method, we apply it to the textbook examples of plane-wave, spherical-wave, and Bessel light. Moreover, we investigate the projection of angular momentum for the photons emitted in the process of the radiative recombination with ionic targets. It is found that the recombination photons do carry a nonzero projection of the orbital angular momentum.

Period changes of the sample of eclipsing binaries with active chromospheres

NASA Astrophysics Data System (ADS)

Jableka, D.; Zola, S.; Zakrzewski, B.; Szymanski, T.; Kuzmicz, A.; de Villiers, S. N.; Zejda, M.; Koziel-Wierzbowska, D.

2012-11-01

In this work we present results derived from analysis of the O-C behaviour of ten eclipsing binary systems: AR Lac, CG Cyg, HP Aur, MM Her, RS CVn, RT And, SV Cam, V471 Tau, WW Dra and CF Tuc. It was proved on the basis of moments of minima compiled from the literature and new ones determined from recent observations, that these binaries show long term (19-91 years) modulations of their orbital periods, clearly visible in their O-C diagrams. Two possible explanations for this effect are considered: (1) the light-travel time effect due to the presence of a third body orbiting the eclipsing systems; (2) the Applegate mechanism predicting period modulation by changes in the distribution of angular momentum as a star goes through its activity cycles. It was found that in the case of four systems the existence of a third star, orbiting the binary, is a more plausible explanation of observations.

Professional tennis players' serve: correlation between segmental angular momentums and ball velocity.

PubMed

Martin, Caroline; Kulpa, Richard; Delamarche, Paul; Bideau, Benoit

2013-03-01

The purpose of the study was to identify the relationships between segmental angular momentum and ball velocity between the following events: ball toss, maximal elbow flexion (MEF), racket lowest point (RLP), maximal shoulder external rotation (MER), and ball impact (BI). Ten tennis players performed serves recorded with a real-time motion capture. Mean angular momentums of the trunk, upper arm, forearm, and the hand-racket were calculated. The anteroposterior axis angular momentum of the trunk was significantly related with ball velocity during the MEF-RLP, RLP-MER, and MER-BI phases. The strongest relationships between the transverse-axis angular momentums and ball velocity followed a proximal-to-distal timing sequence that allows the transfer of angular momentum from the trunk (MEF-RLP and RLP-MER phases) to the upper arm (RLP-MER phase), forearm (RLP-MER and MER-BI phases), and the hand-racket (MER-BI phase). Since sequence is crucial for ball velocity, players should increase angular momentums of the trunk during MEF-MER, upper arm during RLP-MER, forearm during RLP-BI, and the hand-racket during MER-BI.

Forming Disc Galaxies In Major Mergers: Radial Density Profiles And Angular Momentum

NASA Astrophysics Data System (ADS)

Peschken, Nicolas; Athanassoula, E.; Rodionov, S. A.; Lambert, J. C.

2017-06-01

In Athanassoula et al. (2016), we used high resolution N-body hydrodynamical simulations to model the major merger between two disc galaxies with a hot gaseous halo each, and showed that the remnant is a spiral galaxy. The two discs are destroyed by the collision, but after the merger, accretion from the surrounding gaseous halo allows the building of a new disc in the remnant galaxy. In Peschken et al. (2017), we used these simulations to study the radial surface density profiles of the remnant galaxies with downbending profiles (type II), i.e. composed of an inner and an outer exponential disc separated by a break. We analyzed the effect of angular momentum on these profiles, and found that the inner and outer disc scalelengths, as well as the break radius, all increase linearly with the total angular momentum of the initial merging system. Following the angular momentum redistribution in our simulations, we find that the disc angular momentum is acquired via accretion from the gaseous halo. Furthermore, high angular momentum systems give more angular momentum to their discs, which affects directly their radial density profile.

Evolution of Post-accretion-induced Collapse Binaries: The Effect of Evaporation

NASA Astrophysics Data System (ADS)

Liu, Wei-Min; Li, Xiang-Dong

2017-12-01

Accretion-induced collapse (AIC) is widely accepted to be one of the formation channels for millisecond pulsars (MSPs). Since the MSPs have high spin-down luminosities, they can immediately start to evaporate their companion stars after birth. In this paper, we present a detailed investigation on the evolution of the post-AIC binaries, taking into account the effect of evaporation both before and during the Roche-lobe overflow process. We discuss the possible influence of the input parameters including the evaporation efficiency, the initial spin period, and the initial surface magnetic field of the newborn neutron star. We compare the calculated results with the traditional low-mass X-ray binary evolution and suggest that they may reproduce at least part of the observed redbacks and black widows in the companion mass–orbital period plane depending on the mechanisms of angular momentum loss associated with evaporation.

Multi-band photometric study of the short-period eclipsing binary GR Boo

NASA Astrophysics Data System (ADS)

Wang, Daimei; Zhang, Liyun; Han, Xianming L.; Lu, Hongpeng

2017-05-01

We present BVRI light curves with complete phase coverage for the short-period (p = 0.377day) eclipsing binary star GR Boo. We carried out the observations using the SARA 90 cm telescope located at Kitt Peak National Observatory. We obtained six new light curve minimum times. By fitting all of the available O-C minimum times, we obtained an updated ephemeris that shows the orbital period of GR Boo is decreasing at a rate of P˙ = - 2.36 ×10-7 days/year. This decrease in its period can be explained by either mass transfer from the more massive component to the less massive one, or angular momentum exchange due to magnetic activities. We also obtained a set of revised orbital parameters using the Wilson & Devinney program. And finally, we concluded that GR Boo is a contact binary with a dark spot.

Bowen-York trumpet data and black-hole simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hannam, Mark; Murchadha, Niall O; Husa, Sascha

2009-12-15

The most popular method to construct initial data for black-hole-binary simulations is the puncture method, in which compactified wormholes are given linear and angular momentum via the Bowen-York extrinsic curvature. When these data are evolved, they quickly approach a trumpet topology, suggesting that it would be preferable to use data that are in trumpet form from the outset. To achieve this, we extend the puncture method to allow the construction of Bowen-York trumpets, including an outline of an existence and uniqueness proof of the solutions. We construct boosted, spinning and binary Bowen-York puncture trumpets using a single-domain pseudospectral elliptic solver,more » and evolve the binary data and compare with standard wormhole-data results. We also show that for boosted trumpets the black-hole mass can be prescribed a priori, without recourse to the iterative procedure that is necessary for wormhole data.« less

Investigations into the thermal non-equilibrium of W UMa-type contact binaries

NASA Astrophysics Data System (ADS)

Xiong, Xiao; Liu, Liang; Qian, Sheng-Bang

2018-05-01

Traditionally, some physical details (e.g., magnetic braking, energy transfer, angular momentum loss, etc.) have to be taken into consideration during investigations into the evolution of contact binaries. However, the real evolutionary processes which usually contain several of these physical mechanisms are very complicated as a result of strong interaction between components. To avoid dealing with these factors, a linear relationship is applied to the temperatures of components. It is found that the higher the mass ratio (M 2/M 1) of a contact system, the weaker the deviation from thermal equilibrium. On this basis, a variation trend of fill-out factor (f) changing with mass ratio can be inferred, which is consistent with observations. Moreover, if we stick to this point of view, it should be natural that the number of semi-detached binaries in the predicted broken-contact phase of relaxation oscillations is less than the number in the contact phase.

How do binary separations depend on cloud initial conditions?

NASA Astrophysics Data System (ADS)

Sterzik, M. F.; Durisen, R. H.; Zinnecker, H.

2003-11-01

We explore the consequences of a star formation scenario in which the isothermal collapse of a rotating, star-forming core is followed by prompt fragmentation into a cluster containing a small number (N <~ 10) of protostars and/or substellar objects. The subsequent evolution of the cluster is assumed to be dominated by dynamical interactions among cluster members, and this establishes the final properties of the binary and multiple systems. The characteristic scale of the fragmenting core is determined by the cloud initial conditions (such as temperature, angular momentum and mass), and we are able to relate the separation distributions of the final binary population to the properties of the star-forming core. Because the fragmentation scale immediately after the isothermal collapse is typically a factor of 3-10 too large, we conjecture that fragmentation into small clusters followed by dynamical evolution is required to account for the observed binary separation distributions. Differences in the environmental properties of the cores are expected to imprint differences on the characteristic dimensions of the binary systems they form. Recent observations of hierarchical systems, differences in binary characteristics among star forming regions and systematic variations in binary properties with primary mass can be interpreted in the context of this scenario.

Creating high-purity angular-momentum-state Rydberg atoms by a pair of unipolar laser pulses

NASA Astrophysics Data System (ADS)

Xin, PeiPei; Cheng, Hong; Zhang, ShanShan; Wang, HanMu; Xu, ZiShan; Liu, HongPing

2018-04-01

We propose a method of producing high-purity angular-momentum-state Rydberg atoms by a pair of unipolar laser pulses. The first positive-polarity optical half-cycle pulse is used to prepare an excited-state wave packet while the second one is less intense, but with opposite polarity and time delayed, and is employed to drag back the escaping free electron and clip the shape of the bound Rydberg wave packet, selectively increasing or decreasing a fraction of the angular-momentum components. An intelligent choice of laser parameters such as phase and amplitude helps us to control the orbital-angular-momentum composition of an electron wave packet with more facility; thus, a specified angular-momentum state with high purity can be achieved. This scheme of producing high-purity angular-momentum-state Rydberg atoms has significant application in quantum-information processing.

``Stable'' Quasi-periodic Oscillations and Black Hole Properties from Diskoseismology

NASA Astrophysics Data System (ADS)

Wagoner, Robert V.; Silbergleit, Alexander S.; Ortega-Rodríguez, Manuel

2001-09-01

We compare our calculations of the frequencies of the fundamental g-, c-, and p-modes of relativistic thin accretion disks with recent observations of high-frequency quasi-periodic oscillations (QPOs) in X-ray binaries with black hole candidates. These classes of modes encompass all adiabatic perturbations of such disks. The frequencies of these modes depend mainly on the mass and angular momentum of the black hole; their weak dependence on disk luminosity is also explicitly indicated. Identifying the recently discovered, relatively stable QPO pairs with the fundamental g- and c-modes provides a determination of the mass and angular momentum of the black hole. For GRO J1655-40, M=5.9+/-1.0 Msolar and J=(0.917+/-0.024)GM2/c, in agreement with spectroscopic mass determinations. For GRS 1915+105, M=42.4+/-7.0 Msolar and J=(0.926+/-0.020)GM2/c or (less favored) M=18.2+/-3.1 Msolar and J=(0.701+/-0.043)GM2/c. We briefly address the issues of the amplitude, frequency width, and energy dependence of these QPOs.

Whole-body angular momentum during stair walking using passive and powered lower-limb prostheses.

PubMed

Pickle, Nathaniel T; Wilken, Jason M; Aldridge, Jennifer M; Neptune, Richard R; Silverman, Anne K

2014-10-17

Individuals with a unilateral transtibial amputation have a greater risk of falling compared to able-bodied individuals, and falling on stairs can lead to serious injuries. Individuals with transtibial amputations have lost ankle plantarflexor muscle function, which is critical for regulating whole-body angular momentum to maintain dynamic balance. Recently, powered prostheses have been designed to provide active ankle power generation with the goal of restoring biological ankle function. However, the effects of using a powered prosthesis on the regulation of whole-body angular momentum are unknown. The purpose of this study was to use angular momentum to evaluate dynamic balance in individuals with a transtibial amputation using powered and passive prostheses relative to able-bodied individuals during stair ascent and descent. Ground reaction forces, external moment arms, and joint powers were also investigated to interpret the angular momentum results. A key result was that individuals with an amputation had a larger range of sagittal-plane angular momentum during prosthetic limb stance compared to able-bodied individuals during stair ascent. There were no significant differences in the frontal, transverse, or sagittal-plane ranges of angular momentum or maximum magnitude of the angular momentum vector between the passive and powered prostheses during stair ascent or descent. These results indicate that individuals with an amputation have altered angular momentum trajectories during stair walking compared to able-bodied individuals, which may contribute to an increased fall risk. The results also suggest that a powered prosthesis provides no distinct advantage over a passive prosthesis in maintaining dynamic balance during stair walking. Copyright © 2014 Elsevier Ltd. All rights reserved.

Forming disc galaxies in major mergers - III. The effect of angular momentum on the radial density profiles of disc galaxies

NASA Astrophysics Data System (ADS)

Peschken, N.; Athanassoula, E.; Rodionov, S. A.

2017-06-01

We study the effect of angular momentum on the surface density profiles of disc galaxies, using high-resolution simulations of major mergers whose remnants have downbending radial density profiles (type II). As described in the previous papers of this series, in this scenario, most of the disc mass is acquired after the collision via accretion from a hot gaseous halo. We find that the inner and outer disc scalelengths, as well as the break radius, correlate with the total angular momentum of the initial merging system, and are larger for high-angular momentum systems. We follow the angular momentum redistribution in our simulated galaxies, and find that like the mass, the disc angular momentum is acquired via accretion, I.e. to the detriment of the gaseous halo. Furthermore, high-angular momentum systems give more angular momentum to their discs, which directly affects their radial density profile. Adding simulations of isolated galaxies to our sample, we find that the correlations are valid also for disc galaxies evolved in isolation. We show that the outer part of the disc at the end of the simulation is populated mainly by inside-out stellar migration, and that in galaxies with higher angular momentum, stars travel radially further out. This, however, does not mean that outer disc stars (in type II discs) were mostly born in the inner disc. Indeed, generally the break radius increases over time, and not taking this into account leads to overestimating the number of stars born in the inner disc.

Georgia tech catalog of gravitational waveforms

NASA Astrophysics Data System (ADS)

Jani, Karan; Healy, James; Clark, James A.; London, Lionel; Laguna, Pablo; Shoemaker, Deirdre

2016-10-01

This paper introduces a catalog of gravitational waveforms from the bank of simulations by the numerical relativity effort at Georgia Tech. Currently, the catalog consists of 452 distinct waveforms from more than 600 binary black hole simulations: 128 of the waveforms are from binaries with black hole spins aligned with the orbital angular momentum, and 324 are from precessing binary black hole systems. The waveforms from binaries with non-spinning black holes have mass-ratios q = m 1/m 2 ≤ 15, and those with precessing, spinning black holes have q ≤ 8. The waveforms expand a moderate number of orbits in the late inspiral, the burst during coalescence, and the ring-down of the final black hole. Examples of waveforms in the catalog matched against the widely used approximate models are presented. In addition, predictions of the mass and spin of the final black hole by phenomenological fits are tested against the results from the simulation bank. The role of the catalog in interpreting the GW150914 event and future massive binary black-hole search in LIGO is discussed. The Georgia Tech catalog is publicly available at einstein.gatech.edu/catalog.

The Angular Momentum of Baryons and Dark Matter Halos Revisited

NASA Technical Reports Server (NTRS)

Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan

2011-01-01

Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive-mesh refinement (AMR), we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r = 0.1R(sub vir). In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/R(sub vir) > 0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its virialised dark matter halo host. This generic result holds for halos of all masses at all redshifts, as radiative cooling ensures that a significant fraction of baryons remain trapped at the centre of the halos. Despite this injection of angular momentum enriched gas, we predict an amount for stellar discs which is in fair agreement with observations at z=0. This arises because the total specific angular momentum of the baryons (gas and stars) remains close to that of dark matter halos. Indeed, our simulations indicate that any differential loss of angular momentum amplitude between the two components is minor even though dark matter halos continuously lose between half and two-thirds of their specific angular momentum modulus as they evolve. In light of our results, a substantial revision of the standard theory of disc formation seems to be required. We propose a new scenario where gas efficiently carries the angular momentum generated by large-scale structure motions deep inside dark matter halos, redistributing it only in the vicinity of the disc.

Dynamical Evolution and Momentum Transfer for Binary Asteroid Systems

NASA Astrophysics Data System (ADS)

Bellerose, Julie

Over the past decade, robotic missions have been sent to small bodies, providing a basic understanding of their environment. Some of these small systems are found to be in pairs, orbiting each other, which are thought to represent about 16% of the near-Earth asteroid population. It is fair to assume that a mission will target a binary asteroid system in the near future as they can enable scientific insight into both the geology and dynamics of asteroids. In previous work, the dynamical evolution of binary systems was investigated for an ellipsoidsphere model. From the dynamics of two celestial bodies, equilibrium configurations and their stability were analyzed. For a given value of angular momentum, it was shown that there are in general two relative equilibrium configurations which are opposite in stability. When perturbations are introduced, we found that the equilibrium states are the minimum energy points of nearby periodic families. General dynamics from unstable to stable configurations were investigated for binaries in close proximity. Accounting for the dynamics of binaries, the dynamics of particles in this gravitational field were also studied. The location of the analogue Lagrangian points and energy associated with them were characterized. The L1 region is a key element for transfers between the bodies. It was shown that L1 can be situated between or inside the bodies depending on the free parameters of the system modifying the transfer possibilities since L1 has a hyperbolic manifold associated with it. In the current work, we look at the L1 region for binary system where the bodies are in relative equilibrium, close to each other. We find that L1 transits from outside to inside the ellipsoid when the mass ratio is larger than 0.6. For binary systems in close proximity with L1 being inside the ellipsoidal body, simulations show that particles on the surface tend to move away from the ellipsoid, toward the spherical primary. We can relate this to the Roche limit of binaries which affect the distribution of mass between the bodies. Other parameters such as the spin rate of a larger spherical primary may also influence particle distribution. Hence, we can map and characterize the mass distribution and momentum exchange that may occur within a closely formed binary systems.

CONSTRAINING MODELS OF TWIN-PEAK QUASI-PERIODIC OSCILLATIONS WITH REALISTIC NEUTRON STAR EQUATIONS OF STATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Török, Gabriel; Goluchová, Katerina; Urbanec, Martin, E-mail: gabriel.torok@gmail.com, E-mail: katka.g@seznam.cz, E-mail: martin.urbanec@physics.cz

2016-12-20

Twin-peak quasi-periodic oscillations (QPOs) are observed in the X-ray power-density spectra of several accreting low-mass neutron star (NS) binaries. In our previous work we have considered several QPO models. We have identified and explored mass–angular-momentum relations implied by individual QPO models for the atoll source 4U 1636-53. In this paper we extend our study and confront QPO models with various NS equations of state (EoS). We start with simplified calculations assuming Kerr background geometry and then present results of detailed calculations considering the influence of NS quadrupole moment (related to rotationally induced NS oblateness) assuming Hartle–Thorne spacetimes. We show that themore » application of concrete EoS together with a particular QPO model yields a specific mass–angular-momentum relation. However, we demonstrate that the degeneracy in mass and angular momentum can be removed when the NS spin frequency inferred from the X-ray burst observations is considered. We inspect a large set of EoS and discuss their compatibility with the considered QPO models. We conclude that when the NS spin frequency in 4U 1636-53 is close to 580 Hz, we can exclude 51 of the 90 considered combinations of EoS and QPO models. We also discuss additional restrictions that may exclude even more combinations. Namely, 13 EOS are compatible with the observed twin-peak QPOs and the relativistic precession model. However, when considering the low-frequency QPOs and Lense–Thirring precession, only 5 EOS are compatible with the model.« less

Low-dimensional organization of angular momentum during walking on a narrow beam.

PubMed

Chiovetto, Enrico; Huber, Meghan E; Sternad, Dagmar; Giese, Martin A

2018-01-08

Walking on a beam is a challenging motor skill that requires the regulation of upright balance and stability. The difficulty in beam walking results from the reduced base of support compared to that afforded by flat ground. One strategy to maintain stability and hence avoid falling off the beam is to rotate the limb segments to control the body's angular momentum. The aim of this study was to examine the coordination of the angular momentum variations during beam walking. We recorded movement kinematics of participants walking on a narrow beam and computed the angular momentum contributions of the body segments with respect to three different axes. Results showed that, despite considerable variability in the movement kinematics, the angular momentum was characterized by a low-dimensional organization based on a small number of segmental coordination patterns. When the angular momentum was computed with respect to the beam axis, the largest fraction of its variation was accounted for by the trunk segment. This simple organization was robust and invariant across all participants. These findings support the hypothesis that control strategies for complex balancing tasks might be easier to understand by investigating angular momentum instead of the segmental kinematics.

A systematic construction of microstate geometries with low angular momentum

NASA Astrophysics Data System (ADS)

Bena, Iosif; Heidmann, Pierre; Ramírez, Pedro F.

2017-10-01

We outline a systematic procedure to obtain horizonless microstate geometries that have the same charges as three-charge five-dimensional black holes with a macroscopically-large horizon area and an arbitrarily-small angular momentum. There are two routes through which such solutions can be constructed: using multi-center Gibbons-Hawking (GH) spaces or using superstratum technology. So far the only solutions corre-sponding to microstate geometries for black holes with no angular momentum have been obtained via superstrata [1], and multi-center Gibbons-Hawking spaces have been believed to give rise only to microstate geometries of BMPV black holes with a large angular mo-mentum [2]. We perform a thorough search throughout the parameter space of smooth horizonless solutions with four GH centers and find that these have an angular momentum that is generally larger than 80% of the cosmic censorship bound. However, we find that solutions with three GH centers and one supertube (which are smooth in six-dimensional supergravity) can have an arbitrarily-low angular momentum. Our construction thus gives a recipe to build large classes of microstate geometries for zero-angular-momentum black holes without resorting to superstratum technology.

Transverse angular momentum in topological photonic crystals

NASA Astrophysics Data System (ADS)

Deng, Wei-Min; Chen, Xiao-Dong; Zhao, Fu-Li; Dong, Jian-Wen

2018-01-01

Engineering local angular momentum of structured light fields in real space enables applications in many fields, in particular, the realization of unidirectional robust transport in topological photonic crystals with a non-trivial Berry vortex in momentum space. Here, we show transverse angular momentum modes in silicon topological photonic crystals when considering transverse electric polarization. Excited by a chiral external source with either transverse spin angular momentum or transverse phase vortex, robust light flow propagating along opposite directions is observed in several kinds of sharp-turn interfaces between two topologically-distinct silicon photonic crystals. A transverse orbital angular momentum mode with alternating phase vortex exists at the boundary of two such photonic crystals. In addition, unidirectional transport is robust to the working frequency even when the ring size or location of the pseudo-spin source varies in a certain range, leading to the superiority of the broadband photonic device. These findings enable one to make use of transverse angular momentum, a kind of degree of freedom, to achieve unidirectional robust transport in the telecom region and other potential applications in integrated photonic circuits, such as on-chip robust delay lines.

Angular momentum transfer in low velocity oblique impacts - Implications for asteroids

NASA Technical Reports Server (NTRS)

Yanagisawa, Masahisa; Eluszkiewicz, Janusz; Ahrens, Thomas J.

1991-01-01

An experimental study has been conducted for the low-velocity oblique impact efficiency of angular momentum transfer, which is defined as that fraction of incident angular momentum that is transferred to the rotation of a target. The results obtained suggest that more energetic impacts are able to transfer angular momentum more efficiently. In the cases of ricochetted projectiles, the fraction of angular momentum carried off by the ejecta was noted to be less than 30 percent. It is suggested that, if asteroid spin rates are due to mutual noncatastrophic collisions and the taxonomic classes are indicative of bulk properties, the differences between corresponding spin rates will be smaller than expected from a consideration of relative strength and density alone.

Intrinsic Angular Momentum of Light.

ERIC Educational Resources Information Center

Santarelli, Vincent

1979-01-01

Derives a familiar torque-angular momentum theorem for the electromagnetic field, and includes the intrinsic torques exerted by the fields on the polarized medium. This inclusion leads to the expressions for the intrinsic angular momentum carried by the radiation traveling through a charge-free medium. (Author/MA)

The Earth-Moon system as a typical binary in the Solar System

NASA Astrophysics Data System (ADS)

Ipatov, S.

2014-07-01

In recent years new arguments in favor of the formation of solid planetesimals by contraction of rarefied preplanetesimals (RPPs) have been found. It is often considered that masses of some RPPs can correspond to masses of solid bodies of diameter about 1000 km. [1] showed that in the vortices launched by the Rossby wave instability in the borders of the dead zone, the solids quickly achieve critical densities and undergo gravitational collapse into protoplanetary embryos in the mass range 0.1-0.6M_E (where M_E is the mass of the Earth). [2] and [3] supposed that transneptunian binaries were formed from RPPs. It was shown in [2] that the angular momenta acquired at collisions of RPPs moving in circular heliocentric orbits could have the same values as the angular momenta of discovered transneptunian and asteroid binaries. [4] obtained that the angular momenta used in [3] as initial data in calculations of the contraction of RPPs leading to formation of transneptunian binaries could be acquired at collisions of two RPPs moving in circular heliocentric orbits. I supposed that the fraction of RPPs collided with other RPPs during their contraction can be about the fraction of small bodies of diameter d>100 km with satellites (among all such small bodies), i.e., it can be about 0.3 for objects formed in the transneptunian belt. The model of collisions of RPPs explains negative angular momenta of some observed binaries, as about 20 percent of collisions of RPPs moving in circular heliocentric orbits lead to retrograde rotation. Note that if all RPPs got their angular momenta at their formation without mutual collisions, then the angular momenta of small bodies without satellites and those with satellites could be similar (but actually they differ considerably). Most of rarefied preasteroids could turn into solid asteroids before they collided with other preasteroids. Some present asteroids can be debris of larger solid bodies, and the formation of many binaries with primaries with d<100 km can be explained by other models (not by contraction of RPPs). [5] noted that the giant impact concept, which is a popular model of the Moon formation, has several weaknesses. In particular, they calculated formation of the Earth-Moon system from a rarefied protoplanet which mass equaled to the mass of the Earth-Moon system. Using the formulas presented in [2], we obtained that the ratio r_K=K_{EM}/K_{s2} of the angular momentum K_{EM} of the Earth-Moon system to the angular momentum K_{s2} at a typical collision of two identical RPPs - Hill spheres, which masses m_2 are equal to 0.5\\cdot1.0123M_E and heliocentric orbits are circular, is about 0.0335. As K_{s2} ∝ (m_2)^{3/5} [2], then K_{s2}=K_{EM} at 2 m_2=0.0335^{3/5}\\cdot 1.0123M_E=0.13M_E. For circular heliocentric orbits, the maximum value of K_{s2} is greater by a factor of 0.6^{-1} than the above typical value. In this case, r_K=0.02 and 0.02^{3/5}=0.096. Therefore, the angular momentum of the Earth-Moon system can be acquired at a collision of two RPPs with a total mass not smaller than the mass of Mars. We suppose that solid proto-Earth and proto-Moon (with masses m_{Eo} and m_{Mo}) could be formed from a RPP (e.g., according to the models of contraction of a RPP [3,5]). Let us consider the model of the growth of proto-Earth and proto-Moon to the present masses of the Earth and the Moon (M_E and 0.0123M_E, respectively) by accumulation of smaller planetesimals for the case when the effective radii of proto-Earth and proto-Moon are proportional to r (where r is a radius of a considered object). Such proportionality can be considered for large enough eccentricities of planetesimals. In this case, r_{Mo}=m_{Mo}/M_E = [ (0.0123)^{-2/3} - k + k \\cdot (m_{Eo}/M_E)^{-2/3})]^{-3/2}, where k=(k_d)^{-2/3}, and k_d is the ratio of the density of the growing Moon to that of the growing Earth (k_d=0.6 for the present Earth and Moon). For r_{Eo}=m_{Eo}/M_E=0.1, we have r_{Mo}=0.0094 at k=1 and r_{Mo}=0.0086 at k=0.6^{-2/3}. At these values of r_{Mo}, the ratio f_M=(0.0123-r_{Mo})/0.0123 of the mass of planetesimals that were accreted by the Moon at the stage of the solid body accumulation to the present mass of the Moon is 0.24 and 0.30, respectively. If we consider that effective radii of the objects are proportional to r^2 (the case of relatively small relative velocities of planetesimals), then at r_{Eo}=0.1 for k_d equal 1 and 0.6, we obtain f_M equal to 0.04 and 0.05, respectively. In the above model, the Moon could acquire up to 1/3 of its mass at the stage of accumulation of solid bodies, while the mass of the growing Earth increased by a factor of ten, but probably the initial mass of a solid proto-Earth exceeded 0.1M_E. Probably, the RPPs that contracted and formed the embryos of other terrestrial planets did not collide with massive RPPs, and therefore they did not get large enough angular momentum needed to form massive satellites.

High energy radiation precursors to the collapse of black holes binaries based on resonating plasma modes

NASA Astrophysics Data System (ADS)

Coppi, B.

2018-05-01

The presence of well organized plasma structures around binary systems of collapsed objects [1,2] (black holes and neutron stars) is proposed in which processes can develop [3] leading to high energy electromagnetic radiation emission immediately before the binary collapse. The formulated theoretical model supporting this argument shows that resonating plasma collective modes can be excited in the relevant magnetized plasma structure. Accordingly, the collapse of the binary approaches, with the loss of angular momentum by emission of gravitational waves [2], the resonance conditions with vertically standing plasma density and magnetic field oscillations are met. Then, secondary plasma modes propagating along the magnetic field are envisioned to be sustained with mode-particle interactions producing the particle populations responsible for the observable electromagnetic radiation emission. Weak evidence for a precursor to the binary collapse reported in Ref. [2], has been offered by the Agile X-γ-ray observatory [4] while the August 17 (2017) event, identified first by the LIGO-Virgo detection of gravitational waves and featuring the inferred collapse of a neutron star binary, improves the evidence of such a precursor. A new set of experimental observations is needed to reassess the presented theory.

Using Photometric Variability to Detect Binarity in the Central Stars of Four Planetary Nebulae, A 43, A 74, NGC 6720, and NGC 6853

NASA Astrophysics Data System (ADS)

Smith, Alexander; De Marco, O.

2007-12-01

Recent observational evidence and theoretical models are challenging the classical paradigm of single star planetary nebula (PN) evolution, suggesting instead that binary stars play a significant role in the process of PN formation. In order to shape the 90% of PN that are non-spherical, the central star must be rotating and have a magnetic field; the most-likely source of the angular momentum needed to sustain magnetic fields is a binary companion. More observational evidence is needed to confirm that the fraction of PN with close binary central stars is indeed higher than the currently known value of 10-15%. As part of an international effort to detect binary central stars (PLAN-B - Panetary Nebula Binaries), we are carrying out a new photometric survey to look for close binary central stars of PN. Here we present the findings for 4 objects: A 43, A 74, NGC 6720, and NGC 6853. NGC 6720 and NGC 6853 show evidence of periodic variability, the former of which might even show one eclipse. Once completed, the survey will assess the binarity of about 100 central stars of PN.

Smoothed dissipative particle dynamics with angular momentum conservation

NASA Astrophysics Data System (ADS)

Müller, Kathrin; Fedosov, Dmitry A.; Gompper, Gerhard

2015-01-01

Smoothed dissipative particle dynamics (SDPD) combines two popular mesoscopic techniques, the smoothed particle hydrodynamics and dissipative particle dynamics (DPD) methods, and can be considered as an improved dissipative particle dynamics approach. Despite several advantages of the SDPD method over the conventional DPD model, the original formulation of SDPD by Español and Revenga (2003) [9], lacks angular momentum conservation, leading to unphysical results for problems where the conservation of angular momentum is essential. To overcome this limitation, we extend the SDPD method by introducing a particle spin variable such that local and global angular momentum conservation is restored. The new SDPD formulation (SDPD+a) is directly derived from the Navier-Stokes equation for fluids with spin, while thermal fluctuations are incorporated similarly to the DPD method. We test the new SDPD method and demonstrate that it properly reproduces fluid transport coefficients. Also, SDPD with angular momentum conservation is validated using two problems: (i) the Taylor-Couette flow with two immiscible fluids and (ii) a tank-treading vesicle in shear flow with a viscosity contrast between inner and outer fluids. For both problems, the new SDPD method leads to simulation predictions in agreement with the corresponding analytical theories, while the original SDPD method fails to capture properly physical characteristics of the systems due to violation of angular momentum conservation. In conclusion, the extended SDPD method with angular momentum conservation provides a new approach to tackle fluid problems such as multiphase flows and vesicle/cell suspensions, where the conservation of angular momentum is essential.

Mass and angular-momentum inequalities for axi-symmetric initial data sets. II. Angular momentum

NASA Astrophysics Data System (ADS)

Chruściel, Piotr T.; Li, Yanyan; Weinstein, Gilbert

2008-10-01

We extend the validity of Dain's angular-momentum inequality to maximal, asymptotically flat, initial data sets on a simply connected manifold with several asymptotically flat ends which are invariant under a U(1) action and which admit a twist potential.

Energy, momentum, and angular momentum of sound pulses.

PubMed

Lekner, John

2017-12-01

Pulse solutions of the wave equation can be expressed as superpositions of scalar monochromatic beam wavefunctions (solutions of the Helmholtz equation). This formulation leads to causal (unidirectional) propagation, in contrast to all currently known closed-form solutions of the wave equation. Application is made to the evaluation of the energy, momentum, and angular momentum of acoustic pulses, as integrals over the beam and pulse weight functions. Equivalence is established between integration over space of the energy, momentum, and angular momentum densities, and integration over the wavevector weight function. The inequality linking the total energy and the total momentum is made explicit in terms of the weight function formulation. It is shown that a general pulse can be viewed as a superposition of phonons, each with energy ℏck, z component of momentum ℏq, and z component of angular momentum ℏm. A closed-form solution of the wave equation is found, which is localized and causal, and its energy and momentum are evaluated explicitly.

Searching for Low-mass Companions of Cepheids, Part II

NASA Astrophysics Data System (ADS)

Remage Evans, Nancy; Tingle, E.; Bond, H. E.; Schaefer, G. H.; Mason, B.; Karovska, M.; Wolk, S.; Pillitteri, I.; DePasquale, J.; Guinan, E.; Engle, S.

2012-01-01

The formation of a binary/multiple system is an effective way to manipulate angular momentum during the star-formation process. The properties of binary systems (separations and mass ratios) are thus the ``fingerprints" of the process. Low mass companions are the most difficult to identify particularly for massive stars. We are conducting a snapshot survey of the nearest Cepheids (5 Msun stars) using the Hubble Space Telescope Wide Field Camera 3 (WFC3) to discover possible resolved low mass companions. The color-magnitude combination is the first approach to identifying probable physical companions. The distributions of mass and separation for these stars will be discussed. Financial suppoet was provided by Hubble grant GO-12215.01-A and the Chandra X-ray Center NASA contract NAS8-03060.

Interpreting angular momentum transfer between electromagnetic multipoles using vector spherical harmonics.

PubMed

Grinter, Roger; Jones, Garth A

2018-02-01

The transfer of angular momentum between a quadrupole emitter and a dipole acceptor is investigated theoretically. Vector spherical harmonics are used to describe the angular part of the field of the mediating photon. Analytical results are presented for predicting angular momentum transfer between the emitter and absorber within a quantum electrodynamical framework. We interpret the allowability of such a process, which appears to violate conservation of angular momentum, in terms of the breakdown of the isotropy of space at the point of photon absorption (detection). That is, collapse of the wavefunction results in loss of all angular momentum information. This is consistent with Noether's Theorem and demystifies some common misconceptions about the nature of the photon. The results have implications for interpreting the detection of photons from multipole sources and offers insight into limits on information that can be extracted from quantum measurements in photonic systems.

Angular momentum conservation law in light-front quantum field theory

DOE PAGES

Chiu, Kelly Yu-Ju; Brodsky, Stanley J.

2017-03-31

We prove the Lorentz invariance of the angular momentum conservation law and the helicity sum rule for relativistic composite systems in the light-front formulation. We explicitly show that j 3, the z -component of the angular momentum remains unchanged under Lorentz transformations generated by the light-front kinematical boost operators. The invariance of j 3 under Lorentz transformations is a feature unique to the front form. Applying the Lorentz invariance of the angular quantum number in the front form, we obtain a selection rule for the orbital angular momentum which can be used to eliminate certain interaction vertices in QED andmore » QCD. We also generalize the selection rule to any renormalizable theory and show that there exists an upper bound on the change of orbital angular momentum in scattering processes at any fixed order in perturbation theory.« less

Angular momentum conservation law in light-front quantum field theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiu, Kelly Yu-Ju; Brodsky, Stanley J.

We prove the Lorentz invariance of the angular momentum conservation law and the helicity sum rule for relativistic composite systems in the light-front formulation. We explicitly show that j 3, the z -component of the angular momentum remains unchanged under Lorentz transformations generated by the light-front kinematical boost operators. The invariance of j 3 under Lorentz transformations is a feature unique to the front form. Applying the Lorentz invariance of the angular quantum number in the front form, we obtain a selection rule for the orbital angular momentum which can be used to eliminate certain interaction vertices in QED andmore » QCD. We also generalize the selection rule to any renormalizable theory and show that there exists an upper bound on the change of orbital angular momentum in scattering processes at any fixed order in perturbation theory.« less

Angular momentum conservation law in light-front quantum field theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiu, Kelly Yu-Ju; Brodsky, Stanley J.

We prove the Lorentz invariance of the angular momentum conservation law and the helicity sum rule for relativistic composite systems in the light-front formulation. We explicitly show that j 3 , the z -component of the angular momentum remains unchanged under Lorentz transformations generated by the light-front kinematical boost operators. The invariance of j 3 under Lorentz transformations is a feature unique to the front form. Applying the Lorentz invariance of the angular quantum number in the front form, we obtain a selection rule for the orbital angular momentum which can be used to eliminate certain interaction vertices in QEDmore » and QCD. We also generalize the selection rule to any renormalizable theory and show that there exists an upper bound on the change of orbital angular momentum in scattering processes at any fixed order in perturbation theory.« less

ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belyaev, Mikhail A.; Rafikov, Roman R.; Stone, James M., E-mail: rrr@astro.princeton.edu

The nature of angular momentum transport in the boundary layers of accretion disks has been one of the central and long-standing issues of accretion disk theory. In this work we demonstrate that acoustic waves excited by supersonic shear in the boundary layer serve as an efficient mechanism of mass, momentum, and energy transport at the interface between the disk and the accreting object. We develop the theory of angular momentum transport by acoustic modes in the boundary layer, and support our findings with three-dimensional hydrodynamical simulations, using an isothermal equation of state. Our first major result is the identification ofmore » three types of global modes in the boundary layer. We derive dispersion relations for each of these modes that accurately capture the pattern speeds observed in simulations to within a few percent. Second, we show that angular momentum transport in the boundary layer is intrinsically nonlocal, and is driven by radiation of angular momentum away from the boundary layer into both the star and the disk. The picture of angular momentum transport in the boundary layer by waves that can travel large distances before dissipating and redistributing angular momentum and energy to the disk and star is incompatible with the conventional notion of local transport by turbulent stresses. Our results have important implications for semianalytical models that describe the spectral emission from boundary layers.« less

Quark orbital dynamics in the proton from lattice QCD: From Ji to Jaffe-Manohar orbital angular momentum

NASA Astrophysics Data System (ADS)

Engelhardt, M.

2017-05-01

Given a Wigner distribution simultaneously characterizing quark transverse positions and momenta in a proton, one can directly evaluate their cross product, i.e., quark orbital angular momentum. The aforementioned distribution can be obtained by generalizing the proton matrix elements of quark bilocal operators which define transverse momentum-dependent parton distributions (TMDs); the transverse momentum information is supplemented with transverse position information by introducing an additional nonzero momentum transfer. A gauge connection between the quarks must be specified in the quark bilocal operators; the staple-shaped gauge link path used in TMD calculations yields the Jaffe-Manohar definition of orbital angular momentum, whereas a straight path yields the Ji definition. An exploratory lattice calculation, performed at the pion mass mπ=518 MeV , is presented which quasicontinuously interpolates between the two definitions and demonstrates that their difference can be clearly resolved. The resulting Ji orbital angular momentum is confronted with traditional evaluations based on Ji's sum rule. Jaffe-Manohar orbital angular momentum is enhanced in magnitude compared to its Ji counterpart.

Electro-optic analyzer of angular momentum hyperentanglement

PubMed Central

Wu, Ziwen; Chen, Lixiang

2016-01-01

Characterizing a high-dimensional entanglement is fundamental in quantum information applications. Here, we propose a theoretical scheme to analyze and characterize the angular momentum hyperentanglement that two photons are entangled simultaneously in spin and orbital angular momentum. Based on the electro-optic sampling with a proposed hyper-entanglement analyzer and the simple matrix operation using Cramer rule, our simulations show that it is possible to retrieve effectively both the information about the degree of polarization entanglement and the spiral spectrum of high-dimensional orbital angular momentum entanglement. PMID:26911530

Models of angular momentum input to a circumterrestrial swarm from encounters with heliocentric planetesimals

NASA Technical Reports Server (NTRS)

Herbert, F.; Davis, D. R.

1984-01-01

Preliminary experiments show that heliocentric planetesimals passing through the Earth environment possess significant angular momentum. However it also appears that these same planetesimals impacting a circularized circumterrestrial planetesimal swarm would likely remove angular momentum (though possibly increasing mean kinetic energy), presumably promoting both swarm infall upon the Earth and escape to heliocentric space. Only a distribution of highly eccentric satellite orbits with mean tangential velocities of a few tens of percent of local circular velocity would be immune against angular momentum loss to passing heliocentric planetesimals.

The mass and angular momentum of reconstructed metric perturbations

NASA Astrophysics Data System (ADS)

van de Meent, Maarten

2017-06-01

We prove a key result regarding the mass and angular momentum content of linear vacuum perturbations of the Kerr metric obtained through the formalism developed by Chrzarnowski, Cohen, and Kegeles (CCK). More precisely, we prove that the Abbott-Deser mass and angular momentum integrals of any such perturbation vanish when that perturbation was obtained from a regular Fourier mode of the Hertz potential. As a corollary we obtain a generalization of previous results on the completion of the ‘no string’ radiation gauge metric perturbation generated by a point particle. We find that for any bound orbit around a Kerr black hole, the mass and angular momentum perturbations completing the CCK metric are simply the energy and angular momentum of the particle ‘outside’ the orbit and vanish ‘inside’ the orbit.

Stunted accretion growth of black holes by combined effect of the flow angular momentum and radiation feedback

NASA Astrophysics Data System (ADS)

Sugimura, Kazuyuki; Hosokawa, Takashi; Yajima, Hidenobu; Inayoshi, Kohei; Omukai, Kazuyuki

2018-05-01

Accretion on to seed black holes (BHs) is believed to play a crucial role in formation of supermassive BHs observed at high-redshift (z > 6). Here, we investigate the combined effect of gas angular momentum and radiation feedback on the accretion flow, by performing 2D axially symmetric radiation hydrodynamics simulations that solve the flow structure across the Bondi radius and the outer part of the accretion disc simultaneously. The accreting gas with finite angular momentum forms a rotationally-supported disc inside the Bondi radius, where the accretion proceeds by the angular momentum transport due to assumed α-type viscosity. We find that the interplay of radiation and angular momentum significantly suppresses accretion even if the radiative feedback is weakened in an equatorial shadowing region. The accretion rate is O(α) ˜ O(0.01 - 0.1) times the Bondi value, where α is the viscosity parameter. By developing an analytical model, we show that such a great reduction of the accretion rate persists unless the angular momentum is so small that the corresponding centrifugal radius is ≲ 0.04 times the Bondi radius. We argue that BHs are hard to grow quickly via rapid mass accretion considering the angular momentum barrier presented in this paper.

Gender difference in older adult's utilization of gravitational and ground reaction force in regulation of angular momentum during stair descent.

PubMed

Singhal, Kunal; Kim, Jemin; Casebolt, Jeffrey; Lee, Sangwoo; Han, Ki-Hoon; Kwon, Young-Hoo

2015-06-01

Angular momentum of the body is a highly controlled quantity signifying stability, therefore, it is essential to understand its regulation during stair descent. The purpose of this study was to investigate how older adults use gravity and ground reaction force to regulate the angular momentum of the body during stair descent. A total of 28 participants (12 male and 16 female; 68.5 years and 69.0 years of mean age respectively) performed stair descent from a level walk in a step-over-step manner at a self-selected speed over a custom made three-step staircase with embedded force plates. Kinematic and force data were used to calculate angular momentum, gravitational moment, and ground reaction force moment about the stance foot center of pressure. Women show a significantly greater change in normalized angular momentum (0.92Nms/Kgm; p=.004) as compared to men (0.45Nms/Kgm). Women produce higher normalized GRF (p=.031) during the double support phase. The angular momentum changes show largest backward regulation for Step 0 and forward regulation for Step 2. This greater difference in overall change in the angular momentum in women may explain their increased risk of fall over the stairs. Copyright © 2015 Elsevier B.V. All rights reserved.

How do accretion discs break?

NASA Astrophysics Data System (ADS)

Dogan, Suzan

2016-07-01

Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. In this study, we first calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. We compare the disc precession torque with the disc viscous torque to determine whether the disc should warp or break. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. To check our analytical findings, we perform 3D hydrodynamical numerical simulations using the PHANTOM smoothed particle hydrodynamics code, and confirm that disc breaking is widespread and enhances accretion on to the central object. For some inclinations, the disc goes through strong Kozai cycles. Disc breaking promotes markedly enhanced and variable accretion and potentially produces high-energy particles or radiation through shocks. This would have significant implications for all binary systems: e.g. accretion outbursts in X-ray binaries and fuelling supermassive black hole (SMBH) binaries. The behaviour we have discussed in this work is relevant to a variety of astrophysical systems, for example X-ray binaries, where the disc plane may be tilted by radiation warping, SMBH binaries, where accretion of misaligned gas can create effectively random inclinations and protostellar binaries, where a disc may be misaligned by a variety of effects such as binary capture/exchange, accretion after binary formation.

Optomechanical measurement of photon spin angular momentum and optical torque in integrated photonic devices.

PubMed

He, Li; Li, Huan; Li, Mo

2016-09-01

Photons carry linear momentum and spin angular momentum when circularly or elliptically polarized. During light-matter interaction, transfer of linear momentum leads to optical forces, whereas transfer of angular momentum induces optical torque. Optical forces including radiation pressure and gradient forces have long been used in optical tweezers and laser cooling. In nanophotonic devices, optical forces can be significantly enhanced, leading to unprecedented optomechanical effects in both classical and quantum regimes. In contrast, to date, the angular momentum of light and the optical torque effect have only been used in optical tweezers but remain unexplored in integrated photonics. We demonstrate the measurement of the spin angular momentum of photons propagating in a birefringent waveguide and the use of optical torque to actuate rotational motion of an optomechanical device. We show that the sign and magnitude of the optical torque are determined by the photon polarization states that are synthesized on the chip. Our study reveals the mechanical effect of photon's polarization degree of freedom and demonstrates its control in integrated photonic devices. Exploiting optical torque and optomechanical interaction with photon angular momentum can lead to torsional cavity optomechanics and optomechanical photon spin-orbit coupling, as well as applications such as optomechanical gyroscopes and torsional magnetometry.

Optomechanical measurement of photon spin angular momentum and optical torque in integrated photonic devices

PubMed Central

He, Li; Li, Huan; Li, Mo

2016-01-01

Photons carry linear momentum and spin angular momentum when circularly or elliptically polarized. During light-matter interaction, transfer of linear momentum leads to optical forces, whereas transfer of angular momentum induces optical torque. Optical forces including radiation pressure and gradient forces have long been used in optical tweezers and laser cooling. In nanophotonic devices, optical forces can be significantly enhanced, leading to unprecedented optomechanical effects in both classical and quantum regimes. In contrast, to date, the angular momentum of light and the optical torque effect have only been used in optical tweezers but remain unexplored in integrated photonics. We demonstrate the measurement of the spin angular momentum of photons propagating in a birefringent waveguide and the use of optical torque to actuate rotational motion of an optomechanical device. We show that the sign and magnitude of the optical torque are determined by the photon polarization states that are synthesized on the chip. Our study reveals the mechanical effect of photon’s polarization degree of freedom and demonstrates its control in integrated photonic devices. Exploiting optical torque and optomechanical interaction with photon angular momentum can lead to torsional cavity optomechanics and optomechanical photon spin-orbit coupling, as well as applications such as optomechanical gyroscopes and torsional magnetometry. PMID:27626072

On Angular Momentum

DOE R&D Accomplishments Database

Schwinger, J.

1952-01-26

The commutation relations of an arbitrary angular momentum vector can be reduced to those of the harmonic oscillator. This provides a powerful method for constructing and developing the properties of angular momentum eigenvectors. In this paper many known theorems are derived in this way, and some new results obtained. Among the topics treated are the properties of the rotation matrices; the addition of two, three, and four angular momenta; and the theory of tensor operators.

A January angular momentum balance in the OSU two-level atmospheric general circulation model

NASA Technical Reports Server (NTRS)

Kim, J.-W.; Grady, W.

1982-01-01

The present investigation is concerned with an analysis of the atmospheric angular momentum balance, based on the simulation data of the Oregon State University two-level atmospheric general circulation model (AGCM). An attempt is also made to gain an understanding of the involved processes. Preliminary results on the angular momentum and mass balance in the AGCM are shown. The basic equations are examined, and questions of turbulent momentum transfer are investigated. The methods of analysis are discussed, taking into account time-averaged balance equations, time and longitude-averaged balance equations, mean meridional circulation, the mean meridional balance of relative angular momentum, and standing and transient components of motion.

Book Review:

NASA Astrophysics Data System (ADS)

Arimondo, Ennio

2004-07-01

For many years the Institute of Physics has published books on hot topics based on a collection of reprints from different journals, including some remarks by the editors of each volume. The book on Optical Angular Momentum, edited by L Allen, S M Barnett and M J Padgett, is a recent addition to the series. It reproduces forty four papers originally published in different journals and in a few cases it provides direct access to works not easily accessible to a web navigator. The collection covers nearly a hundred years of progress in physics, starting from an historic 1909 paper by Poynting, and ending with a 2002 paper by Padgett, Barnett and coworkers on the measurement of the orbital angular momentum of a single photon. The field of optical angular momentum has expanded greatly, creating an interdisciplinary attraction for researchers operating in quantum optics, atomic physics, solid state physics, biophysics and quantum information theory. The development of laser optics, especially the control of single mode sources, has made possible the specific design of optical radiation modes with a high degree of control on the light angular momentum. The editors of this book are important figures in the field of angular momentum, having contributed to key progress in the area. L Allen published an historical paper in 1999, he and M J Padgett (together with M Babiker) produced few years ago a long review article which is today still the most complete basic introduction to the angular momentum of light, while S M Barnett has contributed several high quality papers to the progress of this area of physics. The editors' choice provides an excellent overview to all readers, with papers classified into eight different topics, covering the basic principles of the light and spin and orbital angular momentum, the laboratory tools for creating laser beams carrying orbital angular momentum, the optical forces and torques created by laser beams carrying angular momentum on particles and atoms, the rotational frequency shift, the angular momentum in nonlinear optics, and the entanglement of angular momentum. An introductory part contains the historic paper by Poynting mentioned above, and another one by Beth in 1936 where the angular momentum of light was measured through a mechanical detection. It also includes a paper by Allen written in 2002 as a long foreword to a Special Issue of Journal of Optics B: Quantum and Semiclassical Optics where more recent major developments within this field were illustrated. Both experimental and theoretical aspects of orbital angular momentum are covered, the editors themselves having, in fact, contributed to developments in both aspects. A newcomer to the field will immediately realize the most important issues connected to the generation, propagation and application of laser beams with orbital angular momentum. A reader already acquainted with the main features of the topic may skip the first papers of all the sections listed above, and focus his or her attention to those papers devoted to the more recent developments. This is therefore a book to be considered with great attention by a large community. My only, minor, remark on the choice of the papers reproduced within this book is that applications to solid state physics, such as liquid crystals, are not mentioned. The field keeps expanding. For instance, very recently optical beams bearing optical angular momentum have been recognized as potential systems for doing quantum computation. Optical tweezers have defined a revolution in optical manipulation for research in the fields of biology, physical chemistry and soft condensed matter physics. The angular momentum of light also has applications in atom optics. Good textbooks are essential in establishing and expanding any field; they help broaden the interest in the field and ensure that the next generation of physicists can learn it. The present book satisfies those requirements because it provides to graduate students, to newcomers to the field, and also to experienced researchers an easy access to the basic contributions.

Radar Imaging and Characterization of the Binary Near-Earth Asteroid (185851) 2000 DP107

NASA Astrophysics Data System (ADS)

Naidu, S. P.; Margot, J. L.; Taylor, P. A.; Nolan, M. C.; Busch, M. W.; Benner, L. A. M.; Brozovic, M.; Giorgini, J. D.; Jao, J. S.; Magri, C.

2015-08-01

The potentially hazardous asteroid (185851) 2000 DP107 was the first binary near-Earth asteroid to be imaged. Radar observations in 2000 provided images at 75 m resolution that revealed the shape, orbit, and spin-up formation mechanism of the binary. The asteroid made a more favorable flyby of the Earth in 2008, yielding images at 30 m resolution. We used these data to obtain shape models for the two components and to improve the estimates of the mutual orbit, component masses, and spin periods. The primary has a sidereal spin period of 2.7745 ± 0.0007 hr and is roughly spheroidal with an equivalent diameter of 863 m +/- 5%. It has a mass of 4.656+/- 0.43× {10}11 kg and a density of 1381 ± 244 kg m-3. It exhibits an equatorial ridge similar to the (66391) 1999 KW4 primary; however, the equatorial ridge in this case is not as regular and has a ˜300 m diameter concavity on one side. The secondary has a sidereal spin period of 1.77 ± 0.02 days commensurate with the orbital period. The secondary is slightly elongated and has overall dimensions of 377× 314× 268 m (6% uncertainties). Its mass is 0.178+/- 0.021× {10}11 kg and its density is 1047 ± 230 kg m-3. The mutual orbit has a semimajor axis of 2.659 ± 0.08 km, an eccentricity of 0.019 ± 0.01, and a period of 1.7556 ± 0.0015 days. The normalized total angular momentum of this system exceeds the amount required for the expected spin-up formation mechanism. An increase of angular momentum from non-gravitational forces after binary formation is a possible explanation. The two components have similar radar reflectivity, suggesting a similar composition consistent with formation by spin-up. The secondary appears to exhibit a larger circular polarization ratio than the primary, suggesting a rougher surface or subsurface at radar wavelength scales.

Dual-wavelength laser with topological charge

NASA Astrophysics Data System (ADS)

Yu, Haohai; Xu, Miaomiao; Zhao, Yongguang; Wang, Yicheng; Han, Shuo; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang

2013-09-01

We demonstrate the simultaneous oscillation of different photons with equal orbital angular momentum in solid-state lasers for the first time to our knowledge. Single tunable Hermite-Gaussian (HG0,n) (0 ≤ n ≤ 7) laser modes with dual wavelength were generated using an isotropic cavity. With a mode-converter, the corresponding Laguerre-Gaussian (LG0,n) laser modes were obtained. The oscillating laser modes have two types of photons at the wavelengths of 1077 and 1081 nm and equal orbital angular momentum of nħ per photon. These results identify the possibility of simultaneous oscillation of different photons with equal and controllable orbital angular momentum. It can be proposed that this laser should have promising applications in many fields based on its compact structure, tunable orbital angular momentum, and simultaneous oscillation of different photons with equal orbital angular momentum.

Nearly extremal apparent horizons in simulations of merging black holes

NASA Astrophysics Data System (ADS)

Lovelace, Geoffrey; Scheel, Mark A.; Owen, Robert; Giesler, Matthew; Katebi, Reza; Szilágyi, Béla; Chu, Tony; Demos, Nicholas; Hemberger, Daniel A.; Kidder, Lawrence E.; Pfeiffer, Harald P.; Afshari, Nousha

2015-03-01

The spin angular momentum S of an isolated Kerr black hole is bounded by the surface area A of its apparent horizon: 8π S≤slant A, with equality for extremal black holes. In this paper, we explore the extremality of individual and common apparent horizons for merging, rapidly spinning binary black holes. We consider simulations of merging black holes with equal masses M and initial spin angular momenta aligned with the orbital angular momentum, including new simulations with spin magnitudes up to S/{{M}2}=0.994. We measure the area and (using approximate Killing vectors) the spin on the individual and common apparent horizons, finding that the inequality 8π S\\lt A is satisfied in all cases but is very close to equality on the common apparent horizon at the instant it first appears. We also evaluate the Booth-Fairhurst extremality, whose value for a given apparent horizon depends on the scaling of the horizon’s null normal vectors. In particular, we introduce a gauge-invariant lower bound on the extremality by computing the smallest value that Booth and Fairhurst’s extremality parameter can take for any scaling. Using this lower bound, we conclude that the common horizons are at least moderately close to extremal just after they appear. Finally, following Lovelace et al (2008 Phys. Rev. D 78 084017), we construct quasiequilibrium binary-black hole initial data with ‘overspun’ marginally trapped surfaces with 8π S\\gt A. We show that the overspun surfaces are indeed superextremal: our lower bound on their Booth-Fairhurst extremality exceeds unity. However, we confirm that these superextremal surfaces are always surrounded by marginally outer trapped surfaces (i.e., by apparent horizons) with 8π S\\lt A. The extremality lower bound on the enclosing apparent horizon is always less than unity but can exceed the value for an extremal Kerr black hole.

Faint AGN in z ≳ 6 Lyman-break galaxies powered by cold accretion and rapid angular momentum transport

NASA Astrophysics Data System (ADS)

Muñoz, Joseph A.; Furlanetto, Steven

2012-11-01

We develop a radiation pressure-balanced model for the interstellar medium of high-redshift galaxies that describes many facets of galaxy formation at z ≳ 6, including star formation rates and distributions and gas accretion on to central black holes. We first show that the vertical gravitational force in the disc of such a model is dominated by the disc self-gravity supported by the radiation pressure of ionizing starlight on gas. Constraining our model to reproduce the UV luminosity function of Lyman-break galaxies (LBGs), we limit the available parameter space to wind mass-loading factors one to four times the canonical value for momentum-driven winds. We then focus our study by exploring the effects of different angular momentum transport mechanisms in the galactic disc and find that accretion driven by gravitational torques, such as from linear spiral waves or non-linear orbit crossings, can build up black hole masses by z = 6 consistent with the canonical M-σ relation with a duty cycle of unity, while accretion mediated by a local viscosity such as in an α-disc results in negligible black hole (BH) accretion. Both gravitational torque models produce X-ray emission from active galactic nuclei (AGN) in high-redshift LBGs in excess of the estimated contribution from high-mass X-ray binaries. Using a recent analysis of deep Chandra observations by Cowie et al., we can already begin to rule out the most extreme regions of our parameter space: the inflow velocity of gas through the disc must either be less than one per cent of the disc circular velocity or the X-ray luminosity of the AGN must be substantially obscured. Moderately deeper future observations or larger sample sizes will be able to probe the more reasonable range of angular momentum transport models and obscuring geometries.

Gas kinematics, morphology and angular momentum in the FIRE simulations

NASA Astrophysics Data System (ADS)

El-Badry, Kareem; Quataert, Eliot; Wetzel, Andrew; Hopkins, Philip F.; Weisz, Daniel R.; Chan, T. K.; Fitts, Alex; Boylan-Kolchin, Michael; Kereš, Dušan; Faucher-Giguère, Claude-André; Garrison-Kimmel, Shea

2018-01-01

We study the z = 0 gas kinematics, morphology and angular momentum content of isolated galaxies in a suite of cosmological zoom-in simulations from the FIRE project spanning Mstar = 106-11 M⊙. Gas becomes increasingly rotationally supported with increasing galaxy mass. In the lowest mass galaxies (Mstar < 108 M⊙), gas fails to form a morphological disc and is primarily dispersion and pressure supported. At intermediate masses (Mstar = 108-10 M⊙), galaxies display a wide range of gas kinematics and morphologies, from thin, rotating discs to irregular spheroids with negligible net rotation. All the high-mass (Mstar = 1010-11 M⊙) galaxies form rotationally supported gas discs. Many of the haloes whose galaxies fail to form discs harbour high angular momentum gas in their circumgalactic medium. The ratio of the specific angular momentum of gas in the central galaxy to that of the dark matter halo increases significantly with galaxy mass, from 〈jgas〉/〈jDM〉 ∼ 0.1 at M_star=10^{6-7} M_{⊙} to 〈jgas〉/〈jDM〉 ∼ 2 at Mstar = 1010-11 M⊙. The reduced rotational support in the lowest mass galaxies owes to (a) stellar feedback and the UV background suppressing the accretion of high angular momentum gas at late times, and (b) stellar feedback driving large non-circular gas motions. We broadly reproduce the observed scaling relations between galaxy mass, gas rotation velocity, size and angular momentum, but may somewhat underpredict the incidence of disky, high angular momentum galaxies at the lowest observed masses (Mstar = (106-2 × 107) M⊙). Stars form preferentially from low angular momentum gas near the galactic centre and are less rotationally supported than gas. The common assumption that stars follow the same rotation curve as gas thus substantially overestimates the simulated galaxies' stellar angular momentum, particularly at low masses.

The Role of Binarity in the Angular Momentum Evolution of M Dwarfs

NASA Astrophysics Data System (ADS)

Stauffer, John; Rebull, Luisa; K2 clusters team

2018-01-01

We have analysed K2 light curves for of order a thousand low mass stars in each of the 8 Myr old Upper Sco association, the 125 Myr age Pleiades open cluster and the ~700 Myr old Praesepe cluster. A very large fraction of these stars show well-determined rotation periods with K2, and where the star is a binary, we usually are able to determine periods for both stars. In Upper Sco, where there are ~150 M dwarf binaries with K2 light curves, the binary stars have periods that are much shorter on average and much closer to each other than would be true if drawn at random from the Upper Sco M dwarf single stars. The same is true in the Pleiades,though the size of the differences from the single M dwarf population is smaller. By Praesepe age, the M dwarf binaries are still somewhat rapidly rotating but their period differences are not significantly different from what would be true if drawn by chance from the singles.

Dynamic mass exchange in doubly degenerate binaries. I - 0.9 and 1.2 solar mass stars

NASA Technical Reports Server (NTRS)

Benz, W.; Cameron, A. G. W.; Press, W. H.; Bowers, R. L.

1990-01-01

The dynamic mass exchange process in doubly degenerate binaries was investigated using a three-dimensional numerical simulation of the evolution of a doubly degenerate binary system in which the primary is a 1.2-solar-mass white dwarf and the Roche lobe filling secondary is a 0.9-solar-mass dwarf. The results show that, in a little more than two orbital periods, the secondary is completely destroyed and transformed into a thick disk orbiting about the primary. Since only a very small fraction of the mass (0.0063 solar mass) escapes the system, the evolution of the binary results in the formation of a massive object. This object is composed of three parts, the initial white dwarf primary, a very hot pressure-supported spherical envelope, and a rotationally supported outer disk. The evolution of the system can be understood in terms of a simple analytical model where it is shown that the angular momentum carried by the mass during the transfer and stored in the disk determines the evolution of the system.

Dynamical Asteroseismology: towards improving the theories of stellar structure and (tidal) evolution

NASA Astrophysics Data System (ADS)

Tkachenko, Andrew

2017-10-01

The potential of the dynamical asteroseismology, the research area that builds upon the synergies between the asteroseismology and binary stars research fields, is discussed in this manuscript. We touch upon the following topics: i) the mass discrepancy observed in intermediate-to high-mass main-sequence and evolved binaries as well as in the low mass systems that are still in the pre-main sequence phase of their evolution; ii) the rotationally induced mixing in high-mass stars, in particular how the most recent theoretical predictions and spectroscopic findings compare to the results of asteroseismic investigations; iii) internal gravity waves and their potential role in the evolution of binary star systems and surface nitrogen enrichment in high-mass stars; iv) the tidal evolution theory, in particular how its predictions of spin-orbit synchronisation and orbital circularisation compare to the present-day high-quality observations; v) the tidally-induced pulsations and their role in the angular momentum transport within binary star systems; vi) the scaling relations between fundamental and seismic properties of stars across the entire HR-diagram.

Irradiation-driven Mass Transfer Cycles in Compact Binaries

NASA Astrophysics Data System (ADS)

Büning, A.; Ritter, H.

2005-08-01

We elaborate on the analytical model of Ritter, Zhang, & Kolb (2000) which describes the basic physics of irradiation-driven mass transfer cycles in semi-detached compact binary systems. In particular, we take into account a contribution to the thermal relaxation of the donor star which is unrelated to irradiation and which was neglected in previous studies. We present results of simulations of the evolution of compact binaries undergoing mass transfer cycles, in particular also of systems with a nuclear evolved donor star. These computations have been carried out with a stellar evolution code which computes mass transfer implicitly and models irradiation of the donor star in a point source approximation, thereby allowing for much more realistic simulations than were hitherto possible. We find that low-mass X-ray binaries (LMXBs) and cataclysmic variables (CVs) with orbital periods ⪉ 6hr can undergo mass transfer cycles only for low angular momentum loss rates. CVs containing a giant donor or one near the terminal age main sequence are more stable than previously thought, but can possibly also undergo mass transfer cycles.

Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO

NASA Astrophysics Data System (ADS)

Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Allen, B.; Allen, G.; Allocca, A.; Almoubayyed, H.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; AultONeal, K.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bawaj, M.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chatterjee, D.; Cheeseboro, B. D.; Chen, H. Y.; Chen, Y.; Cheng, H.-P.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davies, G. S.; Davis, D.; Daw, E. J.; Day, B.; De, S.; DeBra, D.; Deelman, E.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Devenson, J.; Devine, R. C.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Duncan, J.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fong, H.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gabel, M.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garufi, F.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Henry, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Ingram, D. R.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J.-M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, W.; Kim, W. S.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Liu, J.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macfoy, S.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña Hernandez, I.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mayani, R.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, A.; Miller, B. B.; Miller, J.; Millhouse, M.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muniz, E. A. M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Nelemans, G.; Nelson, T. J. N.; Neri, M.; Nery, M.; Neunzert, A.; Newport, J. M.; Newton, G.; Ng, K. K. Y.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Noack, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ormiston, R.; Ortega, L. F.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Qiu, S.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rakhmanov, M.; Ramirez, K. E.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Rynge, M.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheuer, J.; Schmidt, E.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stone, R.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Taylor, J. A.; Taylor, R.; Theeg, T.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahi, K.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, M.; Wang, Y.-F.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Whittle, C.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, K. W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wu, G.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, Hang; Yu, Haocun; Yvert, M.; ZadroŻny, A.; Zanolin, M.; Zelenova, T.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.-H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration

2017-07-01

During their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100 M⊙ , with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93 Gpc-3 yr-1 in comoving units at the 90% confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, L.; Qian, S.-B.; Liao, W.-P.

This paper analyzes the first obtained four-color light curves of V396 Mon using the 2003 version of the W-D code. It is confirmed that V396 Mon is a shallow W-type contact binary system with a mass ratio q = 2.554({+-}0.004) and a degree of contact factor f = 18.9%({+-}1.2%). A period investigation based on all available data shows that the period of the system includes a long-term decrease (dP/dt = -8.57 x 10{sup -8} days yr{sup -1}) and an oscillation (A{sub 3} = 0.0160 day, T{sub 3} = 42.4 yr). They are caused by angular momentum loss and light-time effect,more » respectively. The suspect third body is possibly a small M-type star (about 0.31 solar mass). Though some observations indicate that this system has strong magnetic activity, by our analysis we found that the Applegate mechanism cannot explain the periodic changes. This binary is an especially important system according to Qian's statistics of contact binaries as its mass ratio lies near the proposed pivot point about which the physical structure of contact binaries supposedly oscillates.« less

Observation of orbital angular momentum transfer between acoustic and optical vortices in optical fiber.

PubMed

Dashti, Pedram Z; Alhassen, Fares; Lee, Henry P

2006-02-03

Acousto-optic interaction in optical fiber is examined from the perspective of copropagating optical and acoustic vortex modes. Calculation of the acousto-optic coupling coefficient between different optical modes leads to independent conservation of spin and orbital angular momentum of the interacting photons and phonons. We show that the orbital angular momentum of the acoustic vortex can be transferred to a circularly polarized fundamental optical mode to form a stable optical vortex in the fiber carrying orbital angular momentum. The technique provides a useful way of generating stable optical vortices in the fiber medium.

Merger of a white dwarf-neutron star binary to 1029 carat diamonds: origin of the pulsar planets

NASA Astrophysics Data System (ADS)

Margalit, Ben; Metzger, Brian D.

2017-03-01

We show that the merger and tidal disruption of a carbon/oxygen (C/O) white dwarf (WD) by a neutron star (NS) binary companion provides a natural formation scenario for the PSR B1257+12 planetary system. Starting with initial conditions for the debris disc produced of the disrupted WD, we model its long-term viscous evolution, including for the first time the effects of mass and angular momentum loss during the early radiatively inefficient accretion flow (RIAF) phase and accounting for the unusual C/O composition on the disc opacity. For plausible values of the disc viscosity α ∼ 10-3-10-2 and the RIAF mass-loss efficiency, we find that the disc mass remaining near the planet formation radius at the time of solid condensation is sufficient to explain the pulsar planets. Rapid rocky planet formation via gravitational instability of the solid carbon dominated disc is facilitated by the suppression of vertical shear instabilities due to the high solid-to-gas ratio. Additional evidence supporting a WD-NS merger scenario includes (1) the low observed occurrence rate of pulsar planets (≲1 per cent of NS birth), comparable to the expected WD-NS merger rate; (2) accretion by the NS during the RIAF phase is sufficient to spin PSR B1257+12 up to its observed 6 ms period; (3) similar models of 'low angular momentum' discs, such as those produced from supernova fallback, find insufficient mass reaching the planet formation radius. The unusually high space velocity of PSR B1257+12 of ≳326 km s-1 suggests a possible connection to the calcium-rich transients, dim supernovae which occur in the outskirts of their host galaxies and were proposed to result from mergers of WD-NS binaries receiving supernova kicks. The C/O disc composition implied by our model likely results in carbon-rich planets with diamond interiors.

A swing driven by liquid crystals

NASA Astrophysics Data System (ADS)

Cheng, Cheng

Angular momentum in liquid crystals exists as flow, director reorientation, etc. However, it is hard to observe and measure angular momentum in liquid crystals by a direct mechanical approach. Torsion pendulum is a general tool to measure angular momentum by torque balance. Our torsion pendulum can harvest the angular momentum in liquid crystals to make it observable. The oscillation of the pendulum keeps increasing by constructively adding a small angular momentum of liquid crystals each period at the resonant frequency of the pendulum. Its similar to a swing driven by a force at its resonant frequency. For the torsion pendulum, a cage made of two aluminum discs, in which a liquid crystal cell is placed, is suspended between two thin tungsten wires. A gold mirror, which is a part of the optical lever system, is attached on one tungsten wire. As first demonstration, we fabricate a circular hybrid liquid crystal cell, which can induce concentric backflows to generate angular momentum. The alignment on the planar substrate is concentric and tangential. Due to the coupling between director rotation and flow, the induced backflow goes around the cell when we add electrical pulses between top and bottom substrates. The oscillation is observed by a position sensitive detector and analyzed on the basis of Eriksen-Leslie theory. With vacuum condition and synchronous driving system, the oscillation signal is improved. We demonstrate that this torsion pendulum can sensitively detect the angular momentum in liquid crystals.

Demonstrating the conservation of angular momentum using spherical magnets

NASA Astrophysics Data System (ADS)

Lindén, Johan; Slotte, Joakim; Källman, Kjell-Mikael

2018-01-01

An experimental setup for demonstrating the conservation of angular momentum of rotating spherical magnets is described. Two spherical Nd-Fe-B magnets are placed on a double inclined plane and projected towards each other with pre-selected impact parameters ranging from zero to a few tens of millimeters. After impact, the two magnets either revolve vigorously around the common center of mass or stop immediately, depending on the value of the impact parameter. Using a pick-up coil connected to an oscilloscope, the angular frequency for the rotating magnets was measured, and an estimate for the angular momentum was obtained. A high-speed video camera captured the impact and was used for measuring linear and angular velocities of the magnets. A very good agreement between the initial angular momentum before the impact and the final angular momentum of the revolving dumbbell is observed. The two rotating magnets, and the rotating electromagnetic field emanating from them, can also be viewed as a toy model for the newly discovered gravitational waves, where two black holes collide after revolving around each other. (Enhanced online)

Momentum and Energy Assessments with NASA and Other Model and Data Assimilation Systems

NASA Technical Reports Server (NTRS)

Salstein, David; Nelson, Peter; Hu, Wen-Jie; Sud, Yogesh (Technical Monitor)

2001-01-01

Aspects of the angular momentum cycle, energetics, and related diagnostics from a number of models, including some from the Goddard Laboratory for Atmospheres, and from the Atmospheric Model Intercomparison Project (AMIP) are examined. Torques that dynamically excite changes in angular momentum, including strong torques at mountains were studied. The measure of how atmospheric mass from a strong weather signal can notably change the angular momentum is studied. For AMIP, there is a spread in the angular momentum amongst models, while the GLA model does reasonably well compared to the other models in the diagnostics examined, namely angular momentum and water vapor. Trends and interannual variability in water vapor over a lengthy period was examined. The role of the diabatic heating components, especially latent heating, in the energy cycle and the terms converting available potential energy to kinetic energy, among other parts of the energy cycle, are studied. Modes of climate of the atmosphere, especially the Arctic and North Atlantic Oscillations, are analyzed as well.

Binary star formation: gravitational fragmentation followed by capture

NASA Astrophysics Data System (ADS)

Turner, J. A.; Chapman, S. J.; Bhattal, A. S.; Disney, M. J.; Pongracic, H.; Whitworth, A. P.

1995-11-01

We describe in detail one of a sequence of numerical simulations which realize the mechanism of binary star formation proposed by Pringle. In these simulations, collisions between stable molecular cloud clumps produce dense shocked layers, which cool radiatively and fragment gravitationally. The resulting fragments then condense to form protostellar discs, which at the same time fall together and, as a result of tidal and viscous interactions, capture one another to form binary systems. We refer to this mechanism as shock-induced gravitational fragmentation followed by capture, or SGF+C. When the initial clumps are sufficiently massive and/or the Mach number of the collision is sufficiently high, a large number (>~10) of protostellar discs is produced; under these circumstances, the layer fragments first into filaments, and then into beads along the filaments. The marriage of two protostellar discs in this way is `arranged' in the sense that the protostellar discs involved do not form independently. First, they both condense out of the same layer, and probably also out of the same filament within this layer; this significantly increases the likelihood of them interacting dynamically. Secondly, there tends to be alignment between the orbital and spin angular momenta of the interacting protostellar discs, reflecting the fact that these angular momenta derive mainly from the systematic global angular momentum of the off-axis collision which produced the layer; this alignment of the various angular momenta pre-disposes the discs to very dissipative interactions, thereby increasing the probability of producing a strongly bound, long-lasting union. It is a marriage because the binary orbit stabilizes itself rather quickly. Any subsequent orbit evolution, as the protostellar discs `mop up' the surrounding residual gas and interact tidally, tends to harden the orbit. Therefore, as long as a third body does not intervene, the union is binding. Even if a third body does intervene, provided the binary components are well matched (i.e. of comparable mass) and the third body is not too massive, such interventions will - more often than not - harden the orbit further. In two appendices we describe the code used in the simulations presented in this and the companion paper, and the tests performed to demonstrate the code's ability to handle the physical processes involved.

MODELING FLOWS AROUND MERGING BLACK HOLE BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Meter, James R.; Centrella, Joan; Baker, John G.

2010-03-10

Coalescing massive black hole binaries are produced by the mergers of galaxies. The final stages of the black hole coalescence produce strong gravitational radiation that can be detected by the space-borne Laser Interferometer Space Antenna. In cases where the black hole merger takes place in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts of the final merger requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We have taken a step toward solving this problem by mapping the flow ofmore » pressureless matter in the dynamic, three-dimensional general relativistic spacetime around the merging black holes. We find qualitative differences in collision and outflow speeds, including a signature of the merger when the net angular momentum of the matter is low, between the results from single and binary black holes, and between nonrotating and rotating holes in binaries. If future magnetohydrodynamic results confirm these differences, it may allow assessment of the properties of the binaries as well as yielding an identifiable electromagnetic counterpart to the attendant gravitational wave signal.« less

Black Hole Foraging: Feedback Drives Feeding

NASA Astrophysics Data System (ADS)

Dehnen, Walter; King, Andrew

2013-11-01

We suggest a new picture of supermassive black hole (SMBH) growth in galaxy centers. Momentum-driven feedback from an accreting hole gives significant orbital energy, but little angular momentum to the surrounding gas. Once central accretion drops, the feedback weakens and swept-up gas falls back toward the SMBH on near-parabolic orbits. These intersect near the black hole with partially opposed specific angular momenta, causing further infall and ultimately the formation of a small-scale accretion disk. The feeding rates into the disk typically exceed Eddington by factors of a few, growing the hole on the Salpeter timescale and stimulating further feedback. Natural consequences of this picture include (1) the formation and maintenance of a roughly toroidal distribution of obscuring matter near the hole; (2) random orientations of successive accretion disk episodes; (3) the possibility of rapid SMBH growth; (4) tidal disruption of stars and close binaries formed from infalling gas, resulting in visible flares and ejection of hypervelocity stars; (5) super-solar abundances of the matter accreting on to the SMBH; and (6) a lower central dark-matter density, and hence annihilation signal, than adiabatic SMBH growth implies. We also suggest a simple subgrid recipe for implementing this process in numerical simulations.

Revolution evolution: tracing angular momentum during star and planetary system formation

NASA Astrophysics Data System (ADS)

Davies, Claire Louise

2015-04-01

Stars form via the gravitational collapse of molecular clouds during which time the protostellar object contracts by over seven orders of magnitude. If all the angular momentum present in the natal cloud was conserved during collapse, stars would approach rotational velocities rapid enough to tear themselves apart within just a few Myr. In contrast to this, observations of pre-main sequence rotation rates are relatively slow (∼ 1 - 15 days) indicating that significant quantities of angular momentum must be removed from the star. I use observations of fully convective pre-main sequence stars in two well-studied, nearby regions of star formation (namely the Orion Nebula Cluster and Taurus-Auriga) to determine the removal rate of stellar angular momentum. I find the accretion disc-hosting stars to be rotating at a slower rate and contain less specific angular momentum than the disc-less stars. I interpret this as indicating a period of accretion disc-regulated angular momentum evolution followed by near-constant rotational evolution following disc dispersal. Furthermore, assuming that the age spread inferred from the Hertzsprung-Russell diagram constructed for the star forming region is real, I find that the removal rate of angular momentum during the accretion-disc hosting phase to be more rapid than that expected from simple disc-locking theory whereby contraction occurs at a fixed rotation period. This indicates a more efficient process of angular momentum removal must operate, most likely in the form of an accretion-driven stellar wind or outflow emanating from the star-disc interaction. The initial circumstellar envelope that surrounds a protostellar object during the earliest stages of star formation is rotationally flattened into a disc as the star contracts. An effective viscosity, present within the disc, enables the disc to evolve: mass accretes inwards through the disc and onto the star while momentum migrates outwards, forcing the outer regions of the disc to expand. I used spatially resolved submillimetre detections of the dust and gas components of protoplanetary discs, gathered from the literature, to measure the radial extent of discs around low-mass pre-main sequence stars of ∼ 1-10 Myr and probe their viscous evolution. I find no clear observational evidence for the radial expansion of the dust component. However, I find tentative evidence for the expansion ofthe gas component. This suggests that the evolution of the gas and dust components of protoplanetary discs are likely governed by different astrophysical processes. Observations of jets and outflows emanating from protostars and pre-main sequence stars highlight that it may also be possible to remove angular momentum from the circumstellar material. Using the sample of spatially resolved protoplanetary discs, I find no evidence for angular momentum removal during disc evolution. I also use the spatially resolved debris discs from the Submillimetre Common-User Bolometer Array-2 Observations of Nearby Stars survey to constrain the amount of angular momentum retained within planetary systems. This sample is compared to the protoplanetary disc angular momenta and to the angular momentum contained within pre-stellar cores. I find that significant quantities of angular momentum must be removed during disc formation and disc dispersal. This likely occurs via magnetic braking during the formation of the disc, via the launching of a disc or photo-evaporative wind, and/or via ejection of planetary material following dynamical interactions.

Periastron advance in spinning black hole binaries: Gravitational self-force from numerical relativity

NASA Astrophysics Data System (ADS)

Le Tiec, Alexandre; Buonanno, Alessandra; Mroué, Abdul H.; Pfeiffer, Harald P.; Hemberger, Daniel A.; Lovelace, Geoffrey; Kidder, Lawrence E.; Scheel, Mark A.; Szilágyi, Bela; Taylor, Nicholas W.; Teukolsky, Saul A.

2013-12-01

We study the general relativistic periastron advance in spinning black hole binaries on quasicircular orbits, with spins aligned or antialigned with the orbital angular momentum, using numerical-relativity simulations, the post-Newtonian approximation, and black hole perturbation theory. By imposing a symmetry by exchange of the bodies’ labels, we devise an improved version of the perturbative result and use it as the leading term of a new type of expansion in powers of the symmetric mass ratio. This allows us to measure, for the first time, the gravitational self-force effect on the periastron advance of a nonspinning particle orbiting a Kerr black hole of mass M and spin S=-0.5M2, down to separations of order 9M. Comparing the predictions of our improved perturbative expansion with the exact results from numerical simulations of equal-mass and equal-spin binaries, we find a remarkable agreement over a wide range of spins and orbital separations.

Tidal Interaction among Red Giants Close Binary Systems in APOGEE Database

NASA Astrophysics Data System (ADS)

Sun, Meng; Arras, Phil; Majewski, Steven R.; Troup, Nicholas William; Weinberg, Nevin N.

2017-01-01

Motivated by the newly discovered close binary systems in the Apache Point Observatory Galactic Evolution Experiment (APOGEE-1), the tidal evolution of binaries containing a red giant branch (RGB) star with a stellar or substellar companion was investigated. The tide raised by the companion in the RGB star leads to exchange of angular momentum between the orbit and the stellar spin, causing the orbit to contract. The tidal dissipation rate is computed using turbulent viscosity acting on the equilibrium tidal flow, where careful attention is paid to the effects of reduced viscosity for close-in companions. Evolutionary models for the RGB stars, from the zero-age main sequence to the present, were acquired from the MESA code. "Standard" turbulent viscosity gives rise to such a large orbital decay that many observed systems have decay times much shorter than the RGB evolution time. Several theories for "reduced" turbulent viscosity are investigated, and reduce the number of systems with uncomfortably short decay times.

No cataclysmic variables missing: higher merger rate brings into agreement observed and predicted space densities

NASA Astrophysics Data System (ADS)

Belloni, Diogo; Schreiber, Matthias R.; Zorotovic, Mónica; Iłkiewicz, Krystian; Hurley, Jarrod R.; Giersz, Mirek; Lagos, Felipe

2018-06-01

The predicted and observed space density of cataclysmic variables (CVs) have been for a long time discrepant by at least an order of magnitude. The standard model of CV evolution predicts that the vast majority of CVs should be period bouncers, whose space density has been recently measured to be ρ ≲ 2 × 10-5 pc-3. We performed population synthesis of CVs using an updated version of the Binary Stellar Evolution (BSE) code for single and binary star evolution. We find that the recently suggested empirical prescription of consequential angular momentum loss (CAML) brings into agreement predicted and observed space densities of CVs and period bouncers. To progress with our understanding of CV evolution it is crucial to understand the physical mechanism behind empirical CAML. Our changes to the BSE code are also provided in details, which will allow the community to accurately model mass transfer in interacting binaries in which degenerate objects accrete from low-mass main-sequence donor stars.

Phenomenological study of exclusive binary light particle production from antiproton-proton annihilation at FAIR/PANDA

NASA Astrophysics Data System (ADS)

Ying, Wang

2016-08-01

Exclusive binary annihilation reactions induced by antiprotons of momentum from 1.5 to 15 GeV/c can be extensively investigated at FAIR/PANDA [1]. We are especially interested in the channel of charged pion pairs. Whereas this very probable channel constitutes the major background for other processes of interest in the PANDA experiment, it carries unique physical information on the quark content of proton, allowing to test different models (quark counting rules, statistical models,..). To study the binary reactions of light meson formation, we are developing an effective Lagrangian model based on Feynman diagrams which takes into account the virtuality of the exchanged particles. Regge factors [2] and form factors are introduced with parameters which may be adjusted on the existing data. We present preliminary results of our formalism for different reactions of light meson production leading to reliable predictions of cross sections, energy and angular dependencies in the PANDA kinematical range.

Constructive spin-orbital angular momentum coupling can twist materials to create spiral structures in optical vortex illumination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barada, Daisuke; Center for Optical Research and Education; Juman, Guzhaliayi

It was discovered that optical vortices twist isotropic and homogenous materials, e.g., azo-polymer films to form spiral structures on a nano- or micro-scale. However, the formation mechanism has not yet been established theoretically. To understand the mechanism of the spiral surface relief formation in the azo-polymer film, we theoretically investigate the optical radiation force induced in an isotropic and homogeneous material under irradiation using a continuous-wave optical vortex with arbitrary topological charge and polarization. It is revealed that the spiral surface relief formation in azo-polymer films requires the irradiation of optical vortices with a positive (negative) spin angular momentum andmore » a positive (negative) orbital angular momentum (constructive spin-orbital angular momentum coupling), i.e., the degeneracy among the optical vortices with the same total angular momentum is resolved.« less

Extreme Ultraviolet Fractional Orbital Angular Momentum Beams from High Harmonic Generation

PubMed Central

Turpin, Alex; Rego, Laura; Picón, Antonio; San Román, Julio; Hernández-García, Carlos

2017-01-01

We investigate theoretically the generation of extreme-ultraviolet (EUV) beams carrying fractional orbital angular momentum. To this end, we drive high-order harmonic generation with infrared conical refraction (CR) beams. We show that the high-order harmonic beams emitted in the EUV/soft x-ray regime preserve the characteristic signatures of the driving beam, namely ringlike transverse intensity profile and CR-like polarization distribution. As a result, through orbital and spin angular momentum conservation, harmonic beams are emitted with fractional orbital angular momentum, and they can be synthesized into structured attosecond helical beams –or “structured attosecond light springs”– with rotating linear polarization along the azimuth. Our proposal overcomes the state of the art limitations for the generation of light beams far from the visible domain carrying non-integer orbital angular momentum and could be applied in fields such as diffraction imaging, EUV lithography, particle trapping, and super-resolution imaging. PMID:28281655

Kinetic energy and angular momentum of free particles in the gyratonic pp-waves space-times

NASA Astrophysics Data System (ADS)

Maluf, J. W.; da Rocha-Neto, J. F.; Ulhoa, S. C.; Carneiro, F. L.

2018-06-01

Gyratonic pp-waves are exact solutions of Einstein’s equations that represent non-linear gravitational waves endowed with angular momentum. We consider gyratonic pp-waves that travel in the z direction and whose time dependence on the variable is given by Gaussians, so that the waves represent short bursts of gravitational radiation propagating in the z direction. We evaluate numerically the geodesics and velocities of free particles in the space-time of these waves, and find that after the passage of the waves both the kinetic energy and the angular momentum per unit mass of the particles are changed. Therefore there is a transfer of energy and angular momentum between the gravitational field and the free particles, so that the final values of the energy and angular momentum of the free particles may be smaller or larger in magnitude than the initial values.

The Impact of Galactic Winds on the Angular Momentum of Disk Galaxies in the Illustris Simulation

NASA Astrophysics Data System (ADS)

DeFelippis, Daniel; Genel, Shy; Bryan, Greg L.; Fall, S. Michael

2017-05-01

Observed galactic disks have specific angular momenta similar to expectations for typical dark matter halos in ΛCDM. Cosmological hydrodynamical simulations have recently reproduced this similarity in large galaxy samples by including strong galactic winds, but the exact mechanism that achieves this is not yet clear. Here we present an analysis of key aspects contributing to this relation: angular momentum selection and evolution of Lagrangian mass elements as they accrete onto dark matter halos, condense into Milky-Way-scale galaxies, and join the z = 0 stellar phase. We contrast this evolution in the Illustris simulation with that in a simulation without galactic winds, where the z = 0 angular momentum is ≈ 0.6 {dex} lower. We find that winds induce differences between these simulations in several ways: increasing angular momentum, preventing angular momentum loss, and causing z = 0 stars to sample the accretion-time angular momentum distribution of baryons in a biased way. In both simulations, gas loses on average ≈ 0.4 {dex} between accreting onto halos and first accreting onto central galaxies. In Illustris, this is followed by ≈ 0.2 {dex} gains in the “galactic wind fountain” and no further net evolution past the final accretion onto the galaxy. Without feedback, further losses of ≈ 0.2 {dex} occur in the gas phase inside the galaxies. An additional ≈ 0.15 {dex} difference arises from feedback preferentially selecting higher angular momentum gas at accretion by expelling gas that is poorly aligned. These and additional effects of similar magnitude are discussed, suggesting a complex origin of the similarity between the specific angular momenta of galactic disks and typical halos.

Gamma rays as probe of fission and quasi-fission dynamics in the reaction 32S + 197Au near the Coulomb barrier

NASA Astrophysics Data System (ADS)

Pulcini, A.; Vardaci, E.; Kozulin, E.; Ashaduzzaman, M.; Borcea, C.; Bracco, A.; Brambilla, S.; Calinescu, S.; Camera, F.; Ciemala, M.; de Canditiis, B.; Dorvaux, O.; Harca, I. M.; Itkis, I.; Kirakosyan, V. V.; Knyazheva, G.; Kozulina, N.; Kolesov, I. V.; La Rana, G.; Maj, A.; Matea, I.; Novikov, K.; Petrone, C.; Quero, D.; Rath, P.; Saveleva, E.; Schmitt, C.; Sposito, G.; Stezowski, O.; Trzaska, W. H.; Wilson, J.

2018-05-01

Compound nucleus fission and quasi-fission are both binary decay channels whose common properties make the experimental separation between them difficult. A way to achieve this separation could be to probe the angular momentum of the binary fragments. This can be done detecting gamma rays in coincidence with the two fragments. As a case study, the reaction 32S + 197Au near the Coulomb barrier has been performed at the Tandem ALTO facility at IPN ORSAY. ORGAM and PARIS, two different gamma detectors arrays, are coupled with the CORSET detector, a two-arm time-of-flight spectrometer. TOF-TOF data were analyzed to reconstruct the mass-energy distribution of the primary fragments coupled with gamma multiplicity and spectroscopic analysis. Preliminary results of will be shown.

Could SXP 1062 be an Accreting Magnetar?

NASA Astrophysics Data System (ADS)

Fu, Lei; Li, Xiang-Dong

2012-10-01

In this work we explore the possible evolutionary track of the neutron star in the newly discovered Be/X-ray binary SXP 1062, which is believed to be the first X-ray pulsar associated with a supernova remnant. Although no cyclotron feature has been detected to indicate the strength of the neutron star's magnetic field, we show that it may be >~ 1014 G. If so, SXP 1062 may belong to the accreting magnetars in binary systems. We attempt to reconcile the short age and long spin period of the pulsar taking account of different initial parameters and spin-down mechanisms of the neutron star. Our calculated results show that to spin down to a period ~1000 s within 10-40 kyr requires efficient propeller mechanisms. In particular, the model for angular momentum loss under energy conservation seems to be ruled out.

Finding high-order analytic post-Newtonian parameters from a high-precision numerical self-force calculation

NASA Astrophysics Data System (ADS)

Shah, Abhay G.; Friedman, John L.; Whiting, Bernard F.

2014-03-01

We present a novel analytic extraction of high-order post-Newtonian (pN) parameters that govern quasicircular binary systems. Coefficients in the pN expansion of the energy of a binary system can be found from corresponding coefficients in an extreme-mass-ratio inspiral computation of the change ΔU in the redshift factor of a circular orbit at fixed angular velocity. Remarkably, by computing this essentially gauge-invariant quantity to accuracy greater than one part in 10225, and by assuming that a subset of pN coefficients are rational numbers or products of π and a rational, we obtain the exact analytic coefficients. We find the previously unexpected result that the post-Newtonian expansion of ΔU (and of the change ΔΩ in the angular velocity at fixed redshift factor) have conservative terms at half-integral pN order beginning with a 5.5 pN term. This implies the existence of a corresponding 5.5 pN term in the expansion of the energy of a binary system. Coefficients in the pN series that do not belong to the subset just described are obtained to accuracy better than 1 part in 10265-23n at nth pN order. We work in a radiation gauge, finding the radiative part of the metric perturbation from the gauge-invariant Weyl scalar ψ0 via a Hertz potential. We use mode-sum renormalization, and find high-order renormalization coefficients by matching a series in L=ℓ+1/2 to the large-L behavior of the expression for ΔU. The nonradiative parts of the perturbed metric associated with changes in mass and angular momentum are calculated in the Schwarzschild gauge.

Binary-disk interaction. II. Gap-opening criteria for unequal-mass binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Del Valle, Luciano; Escala, Andrés, E-mail: ldelvalleb@gmail.com

We study the interaction of an unequal-mass binary with an isothermal circumbinary disk, motivated by the theoretical and observational evidence that after a major merger of gas-rich galaxies, a massive gaseous disk with a supermassive black hole binary will be formed in the nuclear region. We focus on the gravitational torques that the binary exerts on the disk and how these torques can drive the formation of a gap in the disk. This exchange of angular momentum between the binary and the disk is mainly driven by the gravitational interaction between the binary and a strong nonaxisymmetric density perturbation thatmore » is produced in the disk, in response to the presence of the binary. Using smoothed particle hydrodynamics numerical simulations, we test two gap-opening criteria, one that assumes the geometry of the density perturbation is an ellipsoid/thick spiral and another that assumes a flat spiral geometry for the density perturbation. We find that the flat spiral gap-opening criterion successfully predicts which simulations will have a gap in the disk and which will not. We also study the limiting cases predicted by the gap-opening criteria. Since the viscosity in our simulations is considerably smaller than the expected value in the nuclear regions of gas-rich merging galaxies, we conclude that in such environments the formation of a circumbinary gap is unlikely.« less

SHAPING THE BROWN DWARF DESERT: PREDICTING THE PRIMORDIAL BROWN DWARF BINARY DISTRIBUTIONS FROM TURBULENT FRAGMENTATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jumper, Peter H.; Fisher, Robert T., E-mail: robert.fisher@umassd.edu

2013-05-20

The formation of brown dwarfs (BDs) poses a key challenge to star formation theory. The observed dearth of nearby ({<=}5 AU) BD companions to solar mass stars, known as the BD desert, as well as the tendency for low-mass binary systems to be more tightly bound than stellar binaries, has been cited as evidence for distinct formation mechanisms for BDs and stars. In this paper, we explore the implications of the minimal hypothesis that BDs in binary systems originate via the same fundamental fragmentation mechanism as stars, within isolated, turbulent giant molecular cloud cores. We demonstrate analytically that the scalingmore » of specific angular momentum with turbulent core mass naturally gives rise to the BD desert, as well as wide BD binary systems. Further, we show that the turbulent core fragmentation model also naturally predicts that very low mass binary and BD/BD systems are more tightly bound than stellar systems. In addition, in order to capture the stochastic variation intrinsic to turbulence, we generate 10{sup 4} model turbulent cores with synthetic turbulent velocity fields to show that the turbulent fragmentation model accommodates a small fraction of binary BDs with wide separations, similar to observations. Indeed, the picture which emerges from the turbulent fragmentation model is that a single fragmentation mechanism may largely shape both stellar and BD binary distributions during formation.« less

Equilibrium, stability, and orbital evolution of close binary systems

NASA Technical Reports Server (NTRS)

Lai, Dong; Rasio, Frederic A.; Shapiro, Stuart L.

1994-01-01

We present a new analytic study of the equilibrium and stability properties of close binary systems containing polytropic components. Our method is based on the use of ellipsoidal trial functions in an energy variational principle. We consider both synchronized and nonsynchronized systems, constructing the compressible generalizations of the classical Darwin and Darwin-Riemann configurations. Our method can be applied to a wide variety of binary models where the stellar masses, radii, spins, entropies, and polytropic indices are all allowed to vary over wide ranges and independently for each component. We find that both secular and dynamical instabilities can develop before a Roche limit or contact is reached along a sequence of models with decreasing binary separation. High incompressibility always makes a given binary system more susceptible to these instabilities, but the dependence on the mass ratio is more complicated. As simple applications, we construct models of double degenerate systems and of low-mass main-sequence star binaries. We also discuss the orbital evoltuion of close binary systems under the combined influence of fluid viscosity and secular angular momentum losses from processes like gravitational radiation. We show that the existence of global fluid instabilities can have a profound effect on the terminal evolution of coalescing binaries. The validity of our analytic solutions is examined by means of detailed comparisons with the results of recent numerical fluid calculations in three dimensions.

Arbitrary optical wavefront shaping via spin-to-orbit coupling

NASA Astrophysics Data System (ADS)

Larocque, Hugo; Gagnon-Bischoff, Jérémie; Bouchard, Frédéric; Fickler, Robert; Upham, Jeremy; Boyd, Robert W.; Karimi, Ebrahim

2016-12-01

Converting spin angular momentum to orbital angular momentum has been shown to be a practical and efficient method for generating optical beams carrying orbital angular momentum and possessing a space-varying polarized field. Here, we present novel liquid crystal devices for tailoring the wavefront of optical beams through the Pancharatnam-Berry phase concept. We demonstrate the versatility of these devices by generating an extensive range of optical beams such as beams carrying ±200 units of orbital angular momentum along with Bessel, Airy and Ince-Gauss beams. We characterize both the phase and the polarization properties of the generated beams, confirming our devices’ performance.

Relativistic neutron star merger simulations with non-zero temperature equations of state. I. Variation of binary parameters and equation of state

NASA Astrophysics Data System (ADS)

Oechslin, R.; Janka, H.-T.; Marek, A.

2007-05-01

An extended set of binary neutron star (NS) merger simulations is performed with an approximative treatment of general relativity to systematically investigate the influence of the nuclear equation of state (EoS), the NS masses, and the NS spin states prior to merging. The general relativistic hydrodynamics simulations are based on a conformally flat approximation to the Einstein equations and a Smoothed Particle Hydrodynamics code for the gas treatment. We employ the two non-zero temperature EoSs of Shen et al. (1998a, Nucl. Phys. A, 637, 435; 1998b, Prog. Theor. Phys., 100, 1013) and Lattimer & Swesty (1991, Nucl. Phys. A, 535, 331), which represent a "harder" and a "softer" behavior, respectively, with characteristic differences in the incompressibility at supernuclear densities and in the maximum mass of nonrotating, cold neutron stars. In addition, we use the cold EoS of Akmal et al. (1998, Phys. Rev. C, 58, 1804) with a simple ideal-gas-like extension according to Shibata & Taniguchi (2006, Phys. Rev. D, 73, 064027), in order to compare with their results, and an ideal-gas EoS with parameters fitted to the supernuclear part of the Shen-EoS. We estimate the mass sitting in a dilute "torus" around the future black hole (BH) by requiring the specific angular momentum of the torus matter to be larger than the angular momentum of the ISCO around a Kerr BH with the mass and spin parameter of the compact central remnant. The dynamics and outcome of the models is found to depend strongly on the EoS and on the binary parameters. Larger torus masses are found for asymmetric systems (up to 0.3 M_⊙ for a mass ratio of 0.55), for large initial NSs, and for a NS spin state which corresponds to a larger total angular momentum. We find that the postmerger remnant collapses either immediately or after a short time when employing the soft EoS of Lattimer& Swesty, whereas no sign of post-merging collapse is found within tens of dynamical timescales for all other EoSs used. The typical temperatures in the torus are found to be about 3{-}10 MeV depending on the strength of the shear motion at the collision interface between the NSs and thus depending on the initial NS spins. About 10-3{-}10-2 M_⊙ of NS matter become gravitationally unbound during or right after the merging process. This matter consists of a hot/high-entropy component from the collision interface and (only in case of asymmetric systems) of a cool/low-entropy component from the spiral arm tips. Appendices are only available in electronic form at http://www.aanda.org

D = 5 Einstein-Maxwell-Chern-Simons black holes.

PubMed

Kunz, Jutta; Navarro-Lérida, Francisco

2006-03-03

Five-dimensional Einstein-Maxwell-Chern-Simons theory with a Chern-Simons coefficient lambda = 1 has supersymmetric black holes with a vanishing horizon angular velocity but finite angular momentum. Here supersymmetry is associated with a borderline between stability and instability, since for lambda > 1 a rotational instability arises, where counterrotating black holes appear, whose horizon rotates in the opposite sense to the angular momentum. For lambda > 2 black holes are no longer uniquely characterized by their global charges, and rotating black holes with vanishing angular momentum appear.

Chirality and the angular momentum of light

PubMed Central

Götte, Jörg B.; Barnett, Stephen M.; Yao, Alison M.

2017-01-01

Chirality is exhibited by objects that cannot be rotated into their mirror images. It is far from obvious that this has anything to do with the angular momentum of light, which owes its existence to rotational symmetries. There is nevertheless a subtle connection between chirality and the angular momentum of light. We demonstrate this connection and, in particular, its significance in the context of chiral light–matter interactions. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069764

Planetary nebula progenitors that swallow binary systems

NASA Astrophysics Data System (ADS)

Soker, Noam

2016-01-01

I propose that some irregular messy planetary nebulae (PNe) owe their morphologies to triple-stellar evolution where tight binary systems evolve inside and/or on the outskirts of the envelope of asymptotic giant branch (AGB) stars. In some cases, the tight binary system can survive, in others, it is destroyed. The tight binary system might break up with one star leaving the system. In an alternative evolution, one of the stars of the broken-up tight binary system falls towards the AGB envelope with low specific angular momentum, and drowns in the envelope. In a different type of destruction process, the drag inside the AGB envelope causes the tight binary system to merge. This releases gravitational energy within the AGB envelope, leading to a very asymmetrical envelope ejection, with an irregular and messy PN as a descendant. The evolution of the triple-stellar system can be in a full common envelope evolution or in a grazing envelope evolution. Both before and after destruction (if destruction takes place), the system might launch pairs of opposite jets. One pronounced signature of triple-stellar evolution might be a large departure from axisymmetrical morphology of the descendant PN. I estimate that about one in eight non-spherical PNe is shaped by one of these triple-stellar evolutionary routes.

Classification of Stellar Orbits in Axisymmetric Galaxies

NASA Astrophysics Data System (ADS)

Li, Baile; Holley-Bockelmann, Kelly; Khan, Fazeel Mahmood

2015-09-01

It is known that two supermassive black holes (SMBHs) cannot merge in a spherical galaxy within a Hubble time; an emerging picture is that galaxy geometry, rotation, and large potential perturbations may usher the SMBH binary through the critical three-body scattering phase and ultimately drive the SMBH to coalesce. We explore the orbital content within an N-body model of a mildly flattened, non-rotating, SMBH-embedded elliptical galaxy. When used as the foundation for a study on the SMBH binary coalescence, the black holes bypassed the binary stalling often seen within spherical galaxies and merged on gigayear timescales. Using both frequency-mapping and angular momentum criteria, we identify a wealth of resonant orbits in the axisymmetric model, including saucers, that are absent from an otherwise identical spherical system and that can potentially interact with the binary. We quantified the set of orbits that could be scattered by the SMBH binary, and found that the axisymmetric model contained nearly six times the number of these potential loss cone orbits compared to our equivalent spherical model. In this flattened model, the mass of these orbits is more than three times that of the SMBH, which is consistent with what the SMBH binary needs to scatter to transition into the gravitational wave regime.

Gravitational wave searches for aligned-spin binary neutron stars using nonspinning templates

NASA Astrophysics Data System (ADS)

Cho, Hee-Suk; Lee, Chang-Hwan

2018-01-01

We study gravitational wave searches for merging binary neutron stars (NSs). We use nonspinning template waveforms towards the signals emitted from aligned-spin NS-NS binaries, in which the spins of the NSs are aligned with the orbital angular momentum. We use the TaylorF2 waveform model, which can generate inspiral waveforms emitted from aligned-spin compact binaries. We employ the single effective spin parameter χeff to represent the effect of two component spins (χ1, χ2) on the wave function. For a target system, we choose a binary consisting of the same component masses of 1.4 M ⊙ and consider the spins up to χ i = 0.4. We investigate fitting factors of the nonspinning templates to evaluate their efficiency in gravitational wave searches for the aligned-spin NS-NS binaries. We find that the templates can achieve the fitting factors exceeding 0.97 only for the signals in the range of -0.2 ≲ χeff ≲ 0. Therefore, we demonstrate the necessity of using aligned-spin templates not to lose the signals outside that range. We also show how much the recovered total mass can be biased from the true value depending on the spin of the signal.

CLASSIFICATION OF STELLAR ORBITS IN AXISYMMETRIC GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Baile; Holley-Bockelmann, Kelly; Khan, Fazeel Mahmood, E-mail: baile.li@vanderbilt.edu, E-mail: k.holley@vanderbilt.edu, E-mail: khanfazeel.ist@gmail.com

2015-09-20

It is known that two supermassive black holes (SMBHs) cannot merge in a spherical galaxy within a Hubble time; an emerging picture is that galaxy geometry, rotation, and large potential perturbations may usher the SMBH binary through the critical three-body scattering phase and ultimately drive the SMBH to coalesce. We explore the orbital content within an N-body model of a mildly flattened, non-rotating, SMBH-embedded elliptical galaxy. When used as the foundation for a study on the SMBH binary coalescence, the black holes bypassed the binary stalling often seen within spherical galaxies and merged on gigayear timescales. Using both frequency-mapping andmore » angular momentum criteria, we identify a wealth of resonant orbits in the axisymmetric model, including saucers, that are absent from an otherwise identical spherical system and that can potentially interact with the binary. We quantified the set of orbits that could be scattered by the SMBH binary, and found that the axisymmetric model contained nearly six times the number of these potential loss cone orbits compared to our equivalent spherical model. In this flattened model, the mass of these orbits is more than three times that of the SMBH, which is consistent with what the SMBH binary needs to scatter to transition into the gravitational wave regime.« less

Searching for gravitational waves from compact binaries with precessing spins

NASA Astrophysics Data System (ADS)

Harry, Ian; Privitera, Stephen; Bohé, Alejandro; Buonanno, Alessandra

2016-07-01

Current searches for gravitational waves from compact-object binaries with the LIGO and Virgo observatories employ waveform models with spins aligned (or antialigned) with the orbital angular momentum. Here, we derive a new statistic to search for compact objects carrying generic (precessing) spins. Applying this statistic, we construct banks of both aligned- and generic-spin templates for binary black holes and neutron star-black hole binaries, and compare the effectualness of these banks towards simulated populations of generic-spin systems. We then use these banks in a pipeline analysis of Gaussian noise to measure the increase in background incurred by using generic- instead of aligned-spin banks. Although the generic-spin banks have roughly a factor of ten more templates than the aligned-spin banks, we find an overall improvement in signal recovery at a fixed false-alarm rate for systems with high-mass ratio and highly precessing spins. This gain in sensitivity comes at a small loss of sensitivity (≲4 %) for systems that are already well covered by aligned-spin templates. Since the observation of even a single binary merger with misaligned spins could provide unique astrophysical insights into the formation of these sources, we recommend that the method described here be developed further to mount a viable search for generic-spin binary mergers in LIGO/Virgo data.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Müller, Kathrin, E-mail: k.mueller@fz-juelich.de; Fedosov, Dmitry A., E-mail: d.fedosov@fz-juelich.de; Gompper, Gerhard, E-mail: g.gompper@fz-juelich.de

Smoothed dissipative particle dynamics (SDPD) combines two popular mesoscopic techniques, the smoothed particle hydrodynamics and dissipative particle dynamics (DPD) methods, and can be considered as an improved dissipative particle dynamics approach. Despite several advantages of the SDPD method over the conventional DPD model, the original formulation of SDPD by Español and Revenga (2003) [9], lacks angular momentum conservation, leading to unphysical results for problems where the conservation of angular momentum is essential. To overcome this limitation, we extend the SDPD method by introducing a particle spin variable such that local and global angular momentum conservation is restored. The new SDPDmore » formulation (SDPD+a) is directly derived from the Navier–Stokes equation for fluids with spin, while thermal fluctuations are incorporated similarly to the DPD method. We test the new SDPD method and demonstrate that it properly reproduces fluid transport coefficients. Also, SDPD with angular momentum conservation is validated using two problems: (i) the Taylor–Couette flow with two immiscible fluids and (ii) a tank-treading vesicle in shear flow with a viscosity contrast between inner and outer fluids. For both problems, the new SDPD method leads to simulation predictions in agreement with the corresponding analytical theories, while the original SDPD method fails to capture properly physical characteristics of the systems due to violation of angular momentum conservation. In conclusion, the extended SDPD method with angular momentum conservation provides a new approach to tackle fluid problems such as multiphase flows and vesicle/cell suspensions, where the conservation of angular momentum is essential.« less

Light's Darkness

ScienceCinema

Padgett, Miles [University of Glasgow, Glasgow, Scotland

2017-12-09

Optical vortices and orbital angular momentum are currently topical subjects in the optics literature. Although seemingly esoteric, they are, in fact, the generic state of light and arise whenever three or more plane waves interfere. To be observed by eye the light must be monochromatic. Laser speckle is one such example, where the optical energy circulates around each black spot, giving a local orbital angular momentum. This talk with report three on-going studies. First, when considering a volume of interfering waves, the laser specs map out threads of complete darkness embedded in the light. Do these threads form loops? Links? Or even knots? Second, when looking through a rapidly spinning window, the image of the world on the other side is rotated: true or false? Finally, the entanglement of orbital angular momentum states means measuring how the angular position of one photons sets the angular momentum of another: is this an angular version of the EPR (Einstein, Podolsky, and Rosen) paradox?

Self-organization and symmetry-breaking in two-dimensional plasma turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bos, Wouter J. T.; Neffaa, Salah; Schneider, Kai

The spontaneous self-organization of two-dimensional magnetized plasma is investigated within the framework of magnetohydrodynamics with a particular emphasis on the symmetry-breaking induced by the shape of the confining boundaries. This symmetry-breaking is quantified by the angular momentum, which is shown to be generated rapidly and spontaneously from initial conditions free from angular momentum as soon as the geometry lacks axisymmetry. This effect is illustrated by considering circular, square, and elliptical boundaries. It is shown that the generation of angular momentum in nonaxisymmetric geometries can be enhanced by increasing the magnetic pressure. The effect becomes stronger at higher Reynolds numbers. Themore » generation of magnetic angular momentum (or angular field), previously observed at low Reynolds numbers, becomes weaker at larger Reynolds numbers.« less

Large Quantum Probability Backflow and the Azimuthal Angle-Angular Momentum Uncertainty Relation for an Electron in a Constant Magnetic Field

ERIC Educational Resources Information Center

Strange, P.

2012-01-01

In this paper we demonstrate a surprising aspect of quantum mechanics that is accessible to an undergraduate student. We discuss probability backflow for an electron in a constant magnetic field. It is shown that even for a wavepacket composed entirely of states with negative angular momentum the effective angular momentum can take on positive…

Mechanical evidence of the orbital angular momentum to energy ratio of vortex beams.

PubMed

Demore, Christine E M; Yang, Zhengyi; Volovick, Alexander; Cochran, Sandy; MacDonald, Michael P; Spalding, Gabriel C

2012-05-11

We measure, in a single experiment, both the radiation pressure and the torque due to a wide variety of propagating acoustic vortex beams. The results validate, for the first time directly, the theoretically predicted ratio of the orbital angular momentum to linear momentum in a propagating beam. We experimentally determine this ratio using simultaneous measurements of both the levitation force and the torque on an acoustic absorber exerted by a broad range of helical ultrasonic beams produced by a 1000-element matrix transducer array. In general, beams with helical phase fronts have been shown to contain orbital angular momentum as the result of the azimuthal component of the Poynting vector around the propagation axis. Theory predicts that for both optical and acoustic helical beams the ratio of the angular momentum current of the beam to the power should be given by the ratio of the beam's topological charge to its angular frequency. This direct experimental observation that the ratio of the torque to power does convincingly match the expected value (given by the topological charge to angular frequency ratio of the beam) is a fundamental result.

Orbital Angular Momentum Multiplexing over Visible Light Communication Systems

NASA Astrophysics Data System (ADS)

Tripathi, Hardik Rameshchandra

This thesis proposes and explores the possibility of using Orbital Angular Momentum multiplexing in Visible Light Communication system. Orbital Angular Momentum is mainly applied for laser and optical fiber transmissions, while Visible Light Communication is a technology using the light as a carrier for wireless communication. In this research, the study of the state of art and experiments showing some results on multiplexing based on Orbital Angular Momentum over Visible Light Communication system were done. After completion of the initial stage; research work and simulations were performed on spatial multiplexing over Li-Fi channel modeling. Simulation scenarios which allowed to evaluate the Signal-to-Noise Ratio, Received Power Distribution, Intensity and Illuminance were defined and developed.

Variations in atmospheric angular momentum

NASA Technical Reports Server (NTRS)

Rosen, R. D.; Salstein, D. A.

1981-01-01

Twice-daily values of the atmosphere's angular momentum about the polar axis during the five years from 1976 through 1980 are presented in graphs and a table. The compilation is based on a global data set, incorporating 90 percent of the mass of the atmosphere. The relationship between changes in the angular momentum of the atmosphere and changes in the length of day is described, as are the main sources of error in the data. The variability in angular momentum is revealed in a preliminary fashion by means of a spectral decomposition. The data presented should stimulate comparisons with other measures of the length of day and so provide a basis for greater understanding of Earth-atmosphere interactions.

The evolution of rotating stars. III - Predicted surface rotation velocities for stars which conserve total angular momentum

NASA Technical Reports Server (NTRS)

Endal, A. S.; Sofia, S.

1979-01-01

Predicted surface rotation velocities for Population I stars at 10, 7, 5, 3, and 1.5 solar masses are presented. The surface velocities were computed for angular momentum with no radial redistribution, complete redistribution, and partial redistribution as predicted by consideration of circulation currents in rotating stars. Near the main sequence, rotational effects can reduce the moment of inertia of a star, so nonrotating models underestimate the expected velocities for evolving stars. On the red giant branch, angular momentum redistribution reduces the surface velocity by a factor of 2 or more, relative to the velocity expected for no radial redistribution. This removes the discrepancy between predicted and observed rotation rates for the K giants and makes it unlikely that these stars lose significant amounts of angular momentum by stellar winds. Calculations indicate that improved observations of the red giants in the Hyades cluster can be used to determine how angular momentum is redistributed by convection

Models of Angular Momentum Input to a Circumterrestrial Swarm from Encounters with Heliocentric Planetesimals

NASA Technical Reports Server (NTRS)

Davis, D. R.; Greenberg, R.; Hebert, F.

1985-01-01

Models of lunar origin in which the Moon accretes in orbit about the Earth from material approaching the Earth from heliocentric orbits must overcome a fundamental problem: the approach orbits of such material would be, in the simplest approximation, equally likely to be prograde or retrograde about the Earth, with the result that accretion of such material adds mass but not angular momentum to circumterrestrial satellites. Satellite orbits would then decay due to the resulting drag, ultimately impacting onto the Earth. One possibility for adding both material and angular momentum to Earth orbit is investigated: imbalance in the delivered angular momentum between pro and retrograde Earth passing orbits which arises from the three body dynamics of planetesimals approaching the Earth from heliocentric space. In order to study angular momentum delivery to circumterrestrial satellites, the near Earth velocities were numerically computed as a function of distance from the Earth for a large array of orbits systematically spanning heliocentric phase space.

Spin-up of a rapidly rotating star by angular momentum loss - Effects of general relativity

NASA Technical Reports Server (NTRS)

Cook, Gregory B.; Shapiro, Stuart L.; Teukolsky, Saul A.

1992-01-01

It has recently been shown that a rapidly rotating Newtonian star can spin up by radiating angular momentum. Extremely fast pulsars losing energy and angular momentum by magnetic dipole radiation or gravitational radiation may exhibit this behavior. Here, we show that this phenomenon is more widespread for rapidly rotating stars in general relativity. We construct and tabulate polytropic sequences of fully relativistic rotating stars of constant rest mass and entropy. We find that the range of adiabatic indices allowing spin-up extends somewhat above 4/3 because of the nonlinear effects of relativistic gravity. In addition, there is a new class of 'supramassive' stars which will inevitably spin up by losing angular momentum regardless of their equation of state. A supramassive star, spinning up via angular momentum loss, will ultimately evolve until it becomes unstable to catastrophic collapse to a black hole. Spin-up in a rapidly rotating star may thus be an observational precursor to such collapse.

Orbital-angular-momentum transfer to optically levitated microparticles in vacuum

NASA Astrophysics Data System (ADS)

Mazilu, Michael; Arita, Yoshihiko; Vettenburg, Tom; Auñón, Juan M.; Wright, Ewan M.; Dholakia, Kishan

2016-11-01

We demonstrate the transfer of orbital angular momentum to an optically levitated microparticle in vacuum. The microparticle is placed within a Laguerre-Gaussian beam and orbits the annular beam profile with increasing angular velocity as the air drag coefficient is reduced. We explore the particle dynamics as a function of the topological charge of the levitating beam. Our results reveal that there is a fundamental limit to the orbital angular momentum that may be transferred to a trapped particle, dependent upon the beam parameters and inertial forces present.

On Whether Angular Momentum in Electric and Magnetic Fields Radiates to Infinity

NASA Technical Reports Server (NTRS)

Canning, Francis X.; Knudsen, Steven

2006-01-01

The Feynman Disk experiment and a related thought experiment with a static magnetic field and capacitor are studied. The mechanical torque integrated over time (angular impulse) is related to the angular momentum in the electric/magnetic field. This is not called an electromagnetic field since quasi-static as well as electromagnetic effects are included. The angular momentum in the electric/magnetic field is examined to determine its static and radiative components. This comparison was then examined to see if it clarified the Abraham-Minkowski paradox.

High Fill-out, Extreme Mass Ratio Overcontact Binary Systems. X. The Newly Discovered Binary XY Leonis Minoris

NASA Astrophysics Data System (ADS)

Qian, S.-B.; Liu, L.; Zhu, L.-Y.; He, J.-J.; Yang, Y.-G.; Bernasconi, L.

2011-05-01

The newly discovered short-period close binary star, XY LMi, has been monitored photometrically since 2006. Its light curves are typical EW-type light curves and show complete eclipses with durations of about 80 minutes. Photometric solutions were determined through an analysis of the complete B, V, R, and I light curves using the 2003 version of the Wilson-Devinney code. XY LMi is a high fill-out, extreme mass ratio overcontact binary system with a mass ratio of q = 0.148 and a fill-out factor of f = 74.1%, suggesting that it is in the late evolutionary stage of late-type tidal-locked binary stars. As observed in other overcontact binary stars, evidence for the presence of two dark spots on both components is given. Based on our 19 epochs of eclipse times, we found that the orbital period of the overcontact binary is decreasing continuously at a rate of dP/dt = -1.67 × 10-7 days yr-1, which may be caused by mass transfer from the primary to the secondary and/or angular momentum loss via magnetic stellar wind. The decrease of the orbital period may result in the increase of the fill-out, and finally, it will evolve into a single rapid-rotation star when the fluid surface reaches the outer critical Roche lobe.

Zero-point angular momentum of supersymmetric Penning trap

NASA Astrophysics Data System (ADS)

Zhang, Jian-zu; Xu, Qiang

2000-10-01

The quantum behavior of supersymmetric Penning trap, specially the superpartner of its angular momentum, is investigated in the formulation of multi-dimensional semiunitary transformation of supersymmetric quantum mechanics. In the limit case of vanishing kinetic energy it is found that its lowest angular momentum is 3ℏ/2, which provides a possibility of directly checking the idea of supersymmetric quantum mechanics and thus suggests a possible experimental verification about this prediction.

Nonlinear management of the angular momentum of soliton clusters: Theory and experiment

NASA Astrophysics Data System (ADS)

Fratalocchi, Andrea; Piccardi, Armando; Peccianti, Marco; Assanto, Gaetano

2007-06-01

We demonstrate, both theoretically and experimentally, how to acquire nonlinear control over the angular momentum of a cluster of solitary waves. Our results, stemming from a universal theoretical model, show that the angular momentum can be adjusted by acting on the global energy input in the system. The phenomenon is experimentally ascertained in nematic liquid crystals by observing a power-dependent rotation of a two-soliton ensemble.

Latitudinal Transport of Angular Momentum by Cellular Flows Observed with MDI

NASA Technical Reports Server (NTRS)

Hathaway, David H.; Gilman, Peter A.; Beck, John G.; Rose, M. Franklin (Technical Monitor)

2001-01-01

We have analyzed Doppler velocity images from the MDI instrument on SOHO to determine the latitudinal transport of angular momentum by the cellular photospheric flows. Doppler velocity images from 60-days in May to July of 1996 were processed to remove the p-mode oscillations, the convective blue shift, the axisymmetric flows, and any instrumental artifacts. The remaining cellular flows were examined for evidence of latitudinal angular momentum transport. Small cells show no evidence of any such transport. Cells the size of supergranules (30,000 km in diameter) show strong evidence for a poleward transport of angular momentum. This would be expected if supergranules are influenced by the Coriolis force, and if the cells are elongated in an east-west direction. We find good evidence for just such an east-west elongation of the supergranules. This elongation may be the result of differential rotation shearing the cellular structures. Data simulations of this effect support the conclusion that elongated supergranules transport angular momentum from the equator toward the poles, Cells somewhat larger than supergranules do not show evidence for this poleward transport. Further analysis of the data is planned to determine if the direction of angular momentum transport reverses for even larger cellular structures. The Sun's rapidly rotating equator must be maintained by such transport somewhere within the convection zone.

Staggering of angular momentum distribution in fission

NASA Astrophysics Data System (ADS)

Tamagno, Pierre; Litaize, Olivier

2018-03-01

We review here the role of angular momentum distributions in the fission process. To do so the algorithm implemented in the FIFRELIN code [?] is detailed with special emphasis on the place of fission fragment angular momenta. The usual Rayleigh distribution used for angular momentum distribution is presented and the related model derivation is recalled. Arguments are given to justify why this distribution should not hold for low excitation energy of the fission fragments. An alternative ad hoc expression taking into account low-lying collectiveness is presented as has been implemented in the FIFRELIN code. Yet on observables currently provided by the code, no dramatic impact has been found. To quantify the magnitude of the impact of the low-lying staggering in the angular momentum distribution, a textbook case is considered for the decay of the 144Ba nucleus with low excitation energy.

Searches for continuous gravitational waves from Scorpius X-1 and XTE J1751-305 in LIGO's sixth science run

NASA Astrophysics Data System (ADS)

Meadors, G. D.; Goetz, E.; Riles, K.; Creighton, T.; Robinet, F.

2017-02-01

Scorpius X-1 (Sco X-1) and x-ray transient XTE J1751-305 are low-mass x-ray binaries (LMXBs) that may emit continuous gravitational waves detectable in the band of ground-based interferometric observatories. Neutron stars in LMXBs could reach a torque-balance steady-state equilibrium in which angular momentum addition from infalling matter from the binary companion is balanced by angular momentum loss, conceivably due to gravitational-wave emission. Torque balance predicts a scale for detectable gravitational-wave strain based on observed x-ray flux. This paper describes a search for Sco X-1 and XTE J1751-305 in LIGO science run 6 data using the TwoSpect algorithm, based on searching for orbital modulations in the frequency domain. While no detections are claimed, upper limits on continuous gravitational-wave emission from Sco X-1 are obtained, spanning gravitational-wave frequencies from 40 to 2040 Hz and projected semimajor axes from 0.90 to 1.98 light-seconds. These upper limits are injection validated, equal any previous set in initial LIGO data, and extend over a broader parameter range. At optimal strain sensitivity, achieved at 165 Hz, the 95% confidence level random-polarization upper limit on dimensionless strain h0 is approximately 1.8 ×10-24. The closest approach to the torque-balance limit, within a factor of 27, is also at 165 Hz. Upper limits are set in particular narrow frequency bands of interest for J1751-305. These are the first upper limits known to date on r -mode emission from this XTE source. The TwoSpect method will be used in upcoming searches of Advanced LIGO and Virgo data.

Angular Momentum Evolution of Young Stars in the nearby Scorpius-Centaurus OB Association

NASA Astrophysics Data System (ADS)

Mellon, Samuel N.; Mamajek, Eric E.; Oberst, Thomas E.; Pecaut, Mark J.

2017-07-01

We report the results of a study of archival SuperWASP light curves for stars in Scorpius-Centaurus (Sco-Cen), the nearest OB association. We use SuperWASP time-series photometry to extract rotation periods for 189 candidate members of the Sco-Cen complex and verify that 162 of those are members of the classic Sco-Cen subgroups of Upper Scorpius (US), Upper Centaurus-Lupus (UCL), and Lower Centaurus-Crux (LCC). This study provides the first measurements of rotation periods explicitly for large samples of pre-main-sequence (pre-MS) stars spanning the UCL and LCC subgroups. Our final sample of 157 well-characterized pre-MS stars spans ages of ˜10-20 Myr, spectral types of ˜F3-M0, and masses of M ≃ 0.3-1.5 {{ M }}⊙ {{N}}. For this sample, we find a distribution of stellar rotation periods with a median of P rot ≃ 2.4 days, an overall range of 0.2 < P rot < 8 days, and a fairly well-defined mass-dependent upper envelope of rotation periods. This distribution of periods is consistent with recently developed stellar angular momentum evolution models. These data are significant because they represent an undersampled age range and the number of measurable rotation periods is large compared to recent studies of other regions. We also search for new examples of eclipsing disk or ring systems analogous to 1SWASP J140747.93-394542.6 (J1407), but find none. Our survey yielded five eclipsing binaries, but only one appears to be physically associated with the Sco-Cen complex. V2394 Oph is a heavily reddened (A V ≃ 5 mag) massive contact binary in the LDN 1689 cloud whose Gaia astrometry is clearly consistent with kinematic membership with the Ophiuchus star-forming region.

Orbital period studies of the two contact binaries TZ Bootis and Y Sextantis

NASA Astrophysics Data System (ADS)

Qian, S.; Liu, Q.

2000-03-01

The physical properties of the two A-type contact binaries TZ Boo and Y Sex are nearly the same. In the present paper, many of their published times of light minima are collected and the changes in their orbital periods are analyzed. It is indicated that the orbital period of TZ Boo shows several alternating jumps while it undergoes a secular decrease of -11.8x10-8 days/year. Several random jumps superposed on a secular decrease (-5.5x10-8 days/year) are also found in the period of Y Sex. The secular decrease is usually interpreted as mass transfer from the more to the less massive components, or mass and angular momentum loss (AML) from the systems. According to the AML theory, on the contact stage, the orbital AML is mainly caused by the mass transfer from the less to the more massive component and the mass ratio decreasing and orbital period gradually increasing are the corresponding results. The extremely low mass ratio and orbital angular momentum of the two systems show that they are evolved via AML and the present secular decrease in the periods may suggest that the magnetic activity in the two systems are very strong. The relation between the changes of the orbital periods and the magnetic activity in the two systems are discussed. We think that the interplay between the variable AML and variable magnetic coupling can explain both the jumps and secular decrease in the orbital periods of the two systems. Table~2 and Table~4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strabg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

The evolution of angular momentum among zero-age main-sequence solar-type stars

NASA Technical Reports Server (NTRS)

Soderblom, David R.; Stauffer, John R.; Macgregor, Keith B.; Jones, Burton F.

1993-01-01

We consider a survey of rotation among F, G, and K dwarfs of the Pleiades in the context of other young clusters (Alpha Persei and the Hyades) and pre-main-sequence (PMS) stars (in Taurus-Auriga and Orion) in order to examine how the angular momentum of a star like the sun evolves during its early life on the main sequence. The rotation of PMS stars can be evolved into distributions like those seen in the young clusters if there is only modest, rotation-independent angular momentum loss prior to the ZAMS. Even then, the ultrafast rotators (UFRs, or ZAMS G and K dwarfs with v sin i equal to or greater than 30 km/s) must owe their extra angular momentum to their conditions of formation and to different angular momentum loss rates above a threshold velocity, for it is unlikely that these stars had angular momentum added as they neared the ZAMS, nor can a spread in ages within a cluster account for the range of rotation seen. Only a fraction of solar-type stars are thus capable of becoming UFRs, and it is not a phase that all stars experience. Simple scaling relations (like the Skumanich relation) applied to the observed surface rotation rates of young solar-type stars cannot reproduce the way in which the Pleiades evolve into the Hyades. We argue that invoking internal differential rotation in these ZAMS stars can explain several aspects of the observations and thus can provide a consistent picture of ZAMS angular momentum evolution.

Initial angular momentum and flow in high energy nuclear collisions

NASA Astrophysics Data System (ADS)

Fries, Rainer J.; Chen, Guangyao; Somanathan, Sidharth

2018-03-01

We study the transfer of angular momentum in high energy nuclear collisions from the colliding nuclei to the region around midrapidity, using the classical approximation of the color glass condensate (CGC) picture. We find that the angular momentum shortly after the collision (up to times ˜1 /Qs , where Qs is the saturation scale) is carried by the "β -type" flow of the initial classical gluon field, introduced by some of us earlier. βi˜μ1∇iμ2-μ2∇iμ1 (i =1 ,2 ) describes the rapidity-odd transverse energy flow and emerges from Gauss's law for gluon fields. Here μ1 and μ2 are the averaged color charge fluctuation densities in the two nuclei, respectively. Interestingly, strong coupling calculations using anti-de Sitter/conformal field theory (AdS/CFT) techniques also find an energy flow term featuring this particular combination of nuclear densities. In classical CGC the order of magnitude of the initial angular momentum per rapidity in the reaction plane, at a time 1 /Qs , is |d L2/d η |≈ RAQs-3ɛ¯0/2 at midrapidity, where RA is the nuclear radius, and ɛ¯0 is the average initial energy density. This result emerges as a cancellation between a vortex of energy flow in the reaction plane aligned with the total angular momentum, and energy shear flow opposed to it. We discuss in detail the process of matching classical Yang-Mills results to fluid dynamics. We will argue that dissipative corrections should not be discarded to ensure that macroscopic conservation laws, e.g., for angular momentum, hold. Viscous fluid dynamics tends to dissipate the shear flow contribution that carries angular momentum in boost-invariant fluid systems. This leads to small residual angular momentum around midrapidity at late times for collisions at high energies.

Theoretical issues on the spontaneous rotation of axisymmetric plasmas

NASA Astrophysics Data System (ADS)

Coppi, B.; Zhou, T.

2014-09-01

An extensive series of experiments have confirmed that the observed ‘spontaneous rotation’ phenomenon in axisymmetric plasmas is related to the confinement properties of these plasmas and connected to the excitation of collective modes associated with these properties (Coppi 2000 18th IAEA Fusion Energy Conf. (Sorrento, Italy, 2000) THP 1/17, www-pub.iaea.org/MTCD/publications/PDF/csp_008c/html/node343.htm and Coppi 2002 Nucl. Fusion 42 1). In particular, radially localized modes can extract angular momentum from the plasma column from which they grow while the background plasma has to recoil in the direction opposite to that of the mode phase velocity. In the case of the excitation of the plasma modes at the edge, the loss of their angular momentum can be connected to the directed particle ejection to the surrounding medium. The recoil angular momentum is then redistributed inside the plasma column mainly by the combination of an effective viscous diffusion and an inward angular momentum transport velocity that is connected, for instance, to ion temperature gradient (ITG) driven modes. The linear and quasi-linear theories of the collisionless trapped electron modes and of the toroidal ITG driven modes are re-examined in the context of their influence on angular momentum transport. Internal modes that produce magnetic reconnection and are electromagnetic in nature, acquire characteristic phase velocity directions in high temperature regimes and become relevant to the ‘generation’ of angular momentum. The drift-tearing mode, the ‘complex’ reconnecting mode and the m0 = 1 internal mode belong to this category, the last mode acquiring different features depending on the strength of its driving factor. Toroidal velocity profiles that reproduce the experimental observations are obtained considering a global angular momentum balance equation that includes the localized sources associated with the excited internal electrostatic and electromagnetic modes besides the appropriate diffusive and the inward angular momentum transparent terms.

Non-Colinearity of Angular Velocity and Angular Momentum

ERIC Educational Resources Information Center

Burr, A. F.

1974-01-01

Discusses the principles, construction, and operation of an apparatus which serves to demonstrate the non-colinearity of the angular velocity and momentum vectors as well as the inertial tensors. Applications of the apparatus to teaching of advanced undergraduate mechanics courses are recommended. (CC)

Importance of Including Topography in Numerical Simulations of Venus' Atmospheric Circulation

NASA Astrophysics Data System (ADS)

Parish, H. F.; Schubert, G.; Lebonnois, S.; Covey, C. C.; Walterscheid, R. L.; Grossman, A.

2012-12-01

Venus' atmosphere is characterized by strong superrotation, in which the wind velocities at cloud heights are around 60 times faster than the surface rotation rate. The reasons for this strong superrotation are still not well understood. Since the surface of the planet is both a source and sink of atmospheric angular momentum it is important to understand and properly account for the interactions at the surface-atmosphere boundary. A key aspect of the surface-atmosphere interaction is the topography. Topography has been introduced into different general circulation models (GCMs) of Venus' atmosphere, producing significant, but widely varying effects on the atmospheric circulation. The reasons for the inconsistencies among model results are not well known, but our studies suggest they might be related to the influences of different dynamical cores. In our recent study, we have analyzed the angular momentum budget for two Venus GCMs, the Venus Community Atmosphere model (Venus CAM) and the Laboratoire de Meteorologie Dynamique (LMD) Venus GCM. Because of Venus' low magnitude surface winds, surface friction alone supplies only a relatively weak angular momentum forcing to the atmosphere. We find that if surface friction is introduced without including surface topography, the angular momentum balance of the atmosphere may be dominated by effects such as numerical diffusion, a sponge layer, or other numerical residuals that are generally included in all GCMs, and can themselves be sources of angular momentum. However, we find the mountain torque associated with realistic Venus surface topography supplies a much larger source of angular momentum than the surface friction, and dominates nonphysical numerical terms. (A similar effect occurs for rapidly rotating planets like Earth, but in this case numerical errors in the angular momentum budget are relatively small even in the absence of mountain torque). Even if surface friction dominates numerical terms in the angular momentum budgets of simulations without realistic topography, it must be remembered that there are no observational constraints on model parameterizations of the real surface friction on Venus. It is essential for a planet such as Venus, for which surface friction alone supplies only weak angular momentum forcing, to include surface topography to generate realistic forcing of angular momentum and avoid the influences of numerical artifacts, which can be significant. Venus' topography, as mapped using measurements from the Magellan mission, shows significant hemispheric asymmetry. In this work we examine the impact of this asymmetry using simulations of Venus' circulation with and without topography, within the latest version of the Venus CAM GCM.

Search for gravitational waves from binary black hole inspiral, merger, and ringdown in LIGO-Virgo data from 2009-2010

NASA Astrophysics Data System (ADS)

Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Ast, S.; Aston, S. M.; Astone, P.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballardin, G.; Ballmer, S.; Bao, Y.; Barayoga, J. C. B.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Beck, D.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Benacquista, M.; Berliner, J. M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bhadbade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biswas, R.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Blom, M.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bond, C.; Bondarescu, R.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bouhou, B.; Braccini, S.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burguet-Castell, J.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chalermsongsak, T.; Charlton, P.; Chassande-Mottin, E.; Chen, W.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chua, S. S. Y.; Chung, C. T. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Clayton, J. H.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colacino, C. N.; Colla, A.; Colombini, M.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M.; Coulon, J.-P.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, R. M.; Dahl, K.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Dent, T.; Dergachev, V.; DeRosa, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Paolo Emilio, M.; Di Virgilio, A.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorsher, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Endrőczi, G.; Engel, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Farr, B. F.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franc, J.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M. A.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P. J.; Fyffe, M.; Gair, J.; Galimberti, M.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gáspár, M. E.; Gelencser, G.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Hayau, J.-F.; Heefner, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Hough, J.; Howell, E. J.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Izumi, K.; Jacobson, M.; James, E.; Jang, Y. J.; Jaranowski, P.; Jesse, E.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Keitel, D.; Kelley, D.; Kells, W.; Keppel, D. G.; Keresztes, Z.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, H.; Kim, K.; Kim, N.; Kim, Y. M.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Lam, P. K.; Landry, M.; Langley, A.; Lantz, B.; Lastzka, N.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Leong, J. R.; Leonor, I.; Leroy, N.; Letendre, N.; Lhuillier, V.; Li, J.; Li, T. G. F.; Lindquist, P. E.; Litvine, V.; Liu, Y.; Liu, Z.; Lockerbie, N. A.; Lodhia, D.; Logue, J.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Lubinski, M.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Masserot, A.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meadors, G. D.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Menéndez, D. F.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Moraru, D.; Moreno, G.; Morgado, N.; Morgia, A.; Mori, T.; Morriss, S. R.; Mosca, S.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Müller-Ebhardt, H.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nash, T.; Naticchioni, L.; Necula, V.; Nelson, J.; Neri, I.; Newton, G.; Nguyen, T.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Oldenberg, R. G.; O'Reilly, B.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Palladino, L.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Parisi, M.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Penn, S.; Perreca, A.; Persichetti, G.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pihlaja, M.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Poggiani, R.; Pöld, J.; Postiglione, F.; Poux, C.; Prato, M.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Ramet, C.; Rankins, B.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Roberts, M.; Robertson, N. A.; Robinet, F.; Robinson, C.; Robinson, E. L.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Rolland, L.; Rollins, J. G.; Romano, R.; Romie, J. H.; Rosińska, D.; Röver, C.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sankar, S.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R. L.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sentenac, D.; Sergeev, A.; Shaddock, D. A.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Somiya, K.; Sorazu, B.; Speirits, F. C.; Sperandio, L.; Stefszky, M.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S. E.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Taffarello, L.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Titsler, C.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Tournefier, E.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Vahlbruch, H.; Vajente, G.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van Veggel, A. A.; Vass, S.; Vasuth, M.; Vaulin, R.; Vavoulidis, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Villar, A. E.; Vinet, J.-Y.; Vitale, S.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Wallace, L.; Wan, Y.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wiesner, K.; Wilkinson, C.; Willems, P. A.; Williams, L.; Williams, R.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Wittel, H.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yamamoto, K.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.

2013-01-01

We report a search for gravitational waves from the inspiral, merger and ringdown of binary black holes (BBH) with total mass between 25 and 100 solar masses, in data taken at the LIGO and Virgo observatories between July 7, 2009 and October 20, 2010. The maximum sensitive distance of the detectors over this period for a (20,20)M⊙ coalescence was 300 Mpc. No gravitational wave signals were found. We thus report upper limits on the astrophysical coalescence rates of BBH as a function of the component masses for nonspinning components, and also evaluate the dependence of the search sensitivity on component spins aligned with the orbital angular momentum. We find an upper limit at 90% confidence on the coalescence rate of BBH with nonspinning components of mass between 19 and 28M⊙ of 3.3×10-7 mergers Mpc-3yr-1.

Wigner functions for nonclassical states of a collection of two-level atoms

NASA Technical Reports Server (NTRS)

Agarwal, G. S.; Dowling, Jonathan P.; Schleich, Wolfgang P.

1993-01-01

The general theory of atomic angular momentum states is used to derive the Wigner distribution function for atomic angular momentum number states, coherent states, and squeezed states. These Wigner functions W(theta,phi) are represented as a pseudo-probability distribution in spherical coordinates theta and phi on the surface of a sphere of radius the square root of j(j +1) where j is the total angular momentum.

Consideration of Gravity Gradient Stabilization for Orion

DTIC Science & Technology

1989-03-01

AND ERIC ANDionl STABILIZATION TION. MAY NEED SECOND CONTROL SYSTEM TO CONTROL OVERALL ANGULAR MOMENTUM I MOMENTUM DUMPING I IN RESPONSE TO...FURTHER EXPERIENCE IS GAINED RPEFERS TO ANY DEVICE THAT MAY BEl USED Ift A PRIOCESS TOE ECHANGE ANGULAR MOMENTUM WITH THME SPACIECRAFTI BODY Figure 5...rotating with angular velocity w relative to XYZ. If unit vectors along the X, Y, and Z axes are ij, and k, respectively, the vector r can be written

Hanbury Brown and Twiss interferometry with twisted light.

PubMed

Magaña-Loaiza, Omar S; Mirhosseini, Mohammad; Cross, Robert M; Rafsanjani, Seyed Mohammad Hashemi; Boyd, Robert W

2016-04-01

The rich physics exhibited by random optical wave fields permitted Hanbury Brown and Twiss to unveil fundamental aspects of light. Furthermore, it has been recognized that optical vortices are ubiquitous in random light and that the phase distribution around these optical singularities imprints a spectrum of orbital angular momentum onto a light field. We demonstrate that random fluctuations of intensity give rise to the formation of correlations in the orbital angular momentum components and angular positions of pseudothermal light. The presence of these correlations is manifested through distinct interference structures in the orbital angular momentum-mode distribution of random light. These novel forms of interference correspond to the azimuthal analog of the Hanbury Brown and Twiss effect. This family of effects can be of fundamental importance in applications where entanglement is not required and where correlations in angular position and orbital angular momentum suffice. We also suggest that the azimuthal Hanbury Brown and Twiss effect can be useful in the exploration of novel phenomena in other branches of physics and astrophysics.

Orbital angular momentum of photons, plasmons and neutrinos in a plasma

NASA Astrophysics Data System (ADS)

Mendonca, J. T.; Thidé, Bo; Then, H.; Ali, S.

2009-11-01

We study the exchange of angular momentum between electromagnetic and electrostatic waves in a plasma, due to the stimulated Raman and Brillouin backscatering processes [1]. Angular momentum states for plasmon and phonon fields are introduced for the first time. We demonstrate that these states can be excited by nonlinear wave mixing, associated with the scattering processes. This could be relevant for plasma diagnostics, both in laboratory and in space. Nonlinearly coupled paraxial equations and instability growth rates are derived. The characteristic features of the plasmon modes with finite angular momentum are also discussed. The potential problem is solved and the angular momentum is explicitly calculated [2]. Finally, it is shown that an electron-neutrino beam, propagating in a background plasma, can be decomposed into orbital momentum states, similar to that of photon states. Coupling between different neutrino states, in the presence of a plasma vortex, is considered. We show that plasma vorticity can be transfered to the neutrino beam, which is relevant to the understanding of the neutrino sources in astrophysics. [1] J.T. Mendonca et al., PRL 102, 185005 (2009). [2] S. Ali and J.T. Mendonca, PoP (2009) submitted. [3] J.T. Mendonca and B. Thide, Europhys. Lett. 84, 41001 (2008).

Transfer of Orbital and Spin angular momentum from non-paraxial optical vortex to atomic BEC

NASA Astrophysics Data System (ADS)

Bhowmik, Anal; Mondal, Pradip Kumar; Majumder, Sonjoy; Deb, Bimalendu

2017-04-01

Allen and co-workers first brought up the realization that optical vortex can carry well defined orbital angular momentum (OAM) associated with its spatial mode. Spin angular momentum (SAM) of the light, associated with the polarization, interacts with the internal electronic motion of the atom. The exchange of orbital angular momentum (OAM) between optical vortex and the center-of-mass (CM) motion of an atom or molecule is well known in paraxial approximation. We show that, how the total angular momentum (TAM) of non-paraxial optical vortex is shared with atom, in terms of OAM and SAM. Both the angular momenta are now possible to be transferred to the internal electronic and external CM motion of atom. Here we have studied how the Rabi frequencies of the excitations of two-photon Raman transitions with respect to focusing angles. Also, we investigate the properties of the vortex superposed state for a Bose-Einstein condensate condensate by a single non-paraxial vortex beam. The density distribution of the vortex-antivortex superposed state has a petal structure which is determined by the quantum circulations and proportion of the vortex and antivortex.

Spin angular momentum induced by optical quasi-phonons activated in birefringent uniaxial crystals

NASA Astrophysics Data System (ADS)

Mohamadou, B.; Maïmounatou, B.; Erasmus, R. M.

2017-09-01

The present report formally establishes the expression of the angular momentum of the quasi-phonons induced by linearly polarized light. The transferred mechanical torque due to phonons is then determined from the spin angular momentum and is shown to be measurable from Raman scattering experiments. To investigate this, the electric field due the excited dipoles and the associated macroscopic dielectric polarization vectors were first calculated using a lattice dynamical model in order to derive in a second step the analytical expression of the angular momentum density arising from the inelastic light scattering by quasi-phonons. The numerical results of the calculated angle dependent mode electric fields and the induced spin angular moments as well as the transferred torques were analyzed with regard to some typical behaviors of the interacting modes and it is shown that the fluctuations of the effective charges is their main origin.

Sorting photons of different rotational Doppler shifts (RDS) by orbital angular momentum of single-photon with spin-orbit-RDS entanglement.

PubMed

Chen, Lixiang; She, Weilong

2008-09-15

We demonstrate that single photons from a rotating q-plate exhibit an entanglement in three degrees of freedom of spin, orbital angular momentum, and the rotational Doppler shift (RDS) due to the nonconservation of total spin and orbital angular momenta. We find that the rotational Doppler shift deltaomega = Omega((delta)s + deltal) , where s, l and Omega are quantum numbers of spin, orbital angular momentum, and rotating velocity of the q-plate, respectively. Of interest is that the rotational Doppler shift directly reflects the rotational symmetry of q-plates and can be also expressed as deltaomega = (Omega)n , where n = 2(q-1) denotes the fold number of rotational symmetry. Besides, based on this single-photon spin-orbit-RDS entanglement, we propose an experimental scheme to sort photons of different frequency shifts according to individual orbital angular momentum.

Quantum orbital angular momentum of elliptically symmetric light

NASA Astrophysics Data System (ADS)

Plick, William N.; Krenn, Mario; Fickler, Robert; Ramelow, Sven; Zeilinger, Anton

2013-03-01

We present a quantum-mechanical analysis of the orbital angular momentum of a class of recently discovered elliptically symmetric stable light fields—the so-called Ince-Gauss modes. We study, in a fully quantum formalism, how the orbital angular momentum of these beams varies with their ellipticity, and we discover several compelling features, including nonmonotonic behavior, stable beams with real continuous (noninteger) orbital angular momenta, and orthogonal modes with the same orbital angular momenta. We explore, and explain in detail, the reasons for this behavior. These features may have applications in quantum key distribution, atom trapping, and quantum informatics in general—as the ellipticity opens up an alternative way of navigating the spatial photonic Hilbert space.

First photometric study of ultrashort-period contact binary 1SWASP J140533.33+114639.1

NASA Astrophysics Data System (ADS)

Zhang, Bin; Qian, Sheng-Bang; Michel, Ri; Soonthornthum, Boonrucksar; Zhu, Li-Ying

2018-03-01

In this paper, CCD photometric light curves for the short-period eclipsing binary 1SWASP J140533.33+114639.1 (hereafter J1405) in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney (W-D) code. It is discovered that J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9 ± 0.5% and a mass ratio of q = 1.55 ± 0.02. In order to explain the asymmetric light curves of the system, a cool starspot on the more massive component is employed. This shallow contact eclipsing binary may have been formed from a short-period detached system through orbital shrinkage due to angular momentum loss. Based on the (O – C) method, the variation of orbital period is studied using all the available times of minimum light. The (O – C) diagram reveals that the period is increasing continuously at a rate of dP/dt = +2.09 × 10‑7, d yr‑1, which can be explained by mass transfer from the less massive component to the more massive one.

The Growth of Stellar Mass Black Hole Binaries Trapped in the Accretion Disks of Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Yi, Shu-Xu; Cheng, K. S.; Taam, Ronald E.

2018-06-01

Among the four black hole (BH) binary merger events detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO), six progenitor BHs have masses greater than 20 M ⊙. The existence of such massive BHs suggests that extreme metal-poor stars are the progenitors. An alternative possibility, that a pair of stellar mass BHs each with mass ∼7 M ⊙ increases to >20 M ⊙ via accretion from a disk surrounding a supermassive BH (SMBH) in an active galactic nucleus (AGN), is considered. The growth of mass of the binary and the transfer of orbital angular momentum to the disk accelerates the merger. Based on the recent numerical work of Tang et al., it is found that, in the disk of a low-mass AGN with mass ∼106 M ⊙ and Eddington ratio >0.01, the mass of an individual BH in the binary can grow to >20 M ⊙ before coalescence, provided that accretion takes place at a rate more than 10 times the Eddington value. This mechanism predicts a new class of gravitational wave (GW) sources involving the merger of two extreme Kerr black holes associated with AGNs and a possible electromagnetic wave counterpart.

THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albrecht, Simon; Winn, Joshua N.; Setiawan, Johny

With observations of the EP Cru system, we continue our series of measurements of spin-orbit angles in eclipsing binary star systems, the BANANA project (Binaries Are Not Always Neatly Aligned). We find a close alignment between the sky projections of the rotational and orbital angular momentum vectors for both stars ({beta}{sub p} = -1. Degree-Sign 8 {+-} 1. Degree-Sign 6 and |{beta}{sub s}| < 17 Degree-Sign ). We also derive precise absolute dimensions and stellar ages for this system. The EP Cru and DI Her systems provide an interesting comparison: they have similar stellar types and orbital properties, but DImore » Her is younger and has major spin-orbit misalignments, raising the question of whether EP Cru also had a large misalignment at an earlier phase of evolution. We show that tidal dissipation is an unlikely explanation for the good alignment observed today, because realignment happens on the same timescale as spin-orbit synchronization, and the stars in EP Cru are far from synchronization (they are spinning nine times too quickly). Therefore it seems that some binaries form with aligned axes, while other superficially similar binaries are formed with misaligned axes.« less

THE FINAL SPIN FROM BINARY BLACK HOLES IN QUASI-CIRCULAR ORBITS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hofmann, Fabian; Rezzolla, Luciano; Barausse, Enrico

2016-07-10

We revisit the problem of predicting the spin magnitude and direction of the black hole (BH) resulting from the merger of two BHs with arbitrary masses and spins inspiraling in quasi-circular orbits. We do this by analyzing a catalog of 619 recent numerical-relativity simulations collected from the literature and spanning a large variety of initial conditions. By combining information from the post-Newtonian approximation, the extreme mass-ratio limit, and perturbative calculations, we improve our previously proposed phenomenological formulae for the final remnant spin. In contrast with alternative suggestions in the literature, and in analogy with our previous expressions, the new formulamore » is a simple algebraic function of the initial system parameters and is not restricted to binaries with spins aligned/anti-aligned with the orbital angular momentum but can be employed for fully generic binaries. The accuracy of the new expression is significantly improved, especially for almost extremal progenitor spins and for small mass ratios, yielding an rms error σ ≈ 0.002 for aligned/anti-aligned binaries and σ ≈ 0.006 for generic binaries. Our new formula is suitable for cosmological applications and can be employed robustly in the analysis of the gravitational waveforms from advanced interferometric detectors.« less

EXPLORING A 'FLOW' OF HIGHLY ECCENTRIC BINARIES WITH KEPLER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong Subo; Katz, Boaz; Socrates, Aristotle

2013-01-20

With 16-month of Kepler data, 15 long-period (40-265 days) eclipsing binaries on highly eccentric orbits (minimum e between 0.5 and 0.85) are identified from their closely separated primary and secondary eclipses ({Delta}t{sub I,II} = 3-10 days). These systems confirm the existence of a previously hinted binary population situated near a constant angular momentum track at P(1 - e {sup 2}){sup 3/2} {approx} 15 days, close to the tidal circularization period P{sub circ}. They may be presently migrating due to tidal dissipation and form a steady-state 'flow' ({approx}1% of stars) feeding the close-binary population (few % of stars). If so, futuremore » Kepler data releases will reveal a growing number (dozens) of systems at longer periods, following dN/dlgP {proportional_to} P {sup 1/3} with increasing eccentricities reaching e {yields} 0.98 for P {yields} 1000 days. Radial-velocity follow-up of long-period eclipsing binaries with no secondary eclipses could offer a significantly larger sample. Orders of magnitude more (hundreds) may reveal their presence from periodic 'eccentricity pulses', such as tidal ellipsoidal variations near pericenter passages. Several new few-day-long eccentricity-pulse candidates with long periods (P = 25-80 days) are reported.« less

THE DEPENDENCE OF STELLAR MASS AND ANGULAR MOMENTUM LOSSES ON LATITUDE AND THE INTERACTION OF ACTIVE REGION AND DIPOLAR MAGNETIC FIELDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garraffo, Cecilia; Drake, Jeremy J.; Cohen, Ofer

Rotation evolution of late-type stars is dominated by magnetic braking and the underlying factors that control this angular momentum loss are important for the study of stellar spin-down. In this work, we study angular momentum loss as a function of two different aspects of magnetic activity using a calibrated Alfvén wave-driven magnetohydrodynamic wind model: the strengths of magnetic spots and their distribution in latitude. By driving the model using solar and modified solar surface magnetograms, we show that the topology of the field arising from the net interaction of both small-scale and large-scale field is important for spin-down rates andmore » that angular momentum loss is not a simple function of large scale magnetic field strength. We find that changing the latitude of magnetic spots can modify mass and angular momentum loss rates by a factor of two. The general effect that causes these differences is the closing down of large-scale open field at mid- and high-latitudes by the addition of the small-scale field. These effects might give rise to modulation of mass and angular momentum loss through stellar cycles, and present a problem for ab initio attempts to predict stellar spin-down based on wind models. For all the magnetogram cases considered here, from dipoles to various spotted distributions, we find that angular momentum loss is dominated by the mass loss at mid-latitudes. The spin-down torque applied by magnetized winds therefore acts at specific latitudes and is not evenly distributed over the stellar surface, though this aspect is unlikely to be important for understanding spin-down and surface flows on stars.« less

Unveiling Angular Momentum

NASA Astrophysics Data System (ADS)

Robinson, Stephen

2015-03-01

Angular momentum is a notoriously difficult concept to grasp. Visualization often requires three-dimensional pictures of vectors pointing in seemingly arbitrary directions. A simple student-run laboratory experiment coupled with intuitive explanations by an instructor can clear up some of the inherent ambiguity of rotational motion. Specifically, the precessional period of a suspended spinning bicycle wheel can be related to the spinning frequency through a simple algebraic expression. An explanation of this precession apart from the concept of angular momentum will be given.

Inefficient Angular Momentum Transport in Accretion Disk Boundary Layers: Angular Momentum Belt in the Boundary Layer

NASA Astrophysics Data System (ADS)

Belyaev, Mikhail A.; Quataert, Eliot

2018-04-01

We present unstratified 3D MHD simulations of an accretion disk with a boundary layer (BL) that have a duration ˜1000 orbital periods at the inner radius of the accretion disk. We find the surprising result that angular momentum piles up in the boundary layer, which results in a rapidly rotating belt of accreted material at the surface of the star. The angular momentum stored in this belt increases monotonically in time, which implies that angular momentum transport mechanisms in the BL are inefficient and do not couple the accretion disk to the star. This is in spite of the fact that magnetic fields are advected into the BL from the disk and supersonic shear instabilities in the BL excite acoustic waves. In our simulations, these waves only carry a small fraction (˜10%) of the angular momentum required for steady state accretion. Using analytical theory and 2D viscous simulations in the R - ϕ plane, we derive an analytical criterion for belt formation to occur in the BL in terms of the ratio of the viscosity in the accretion disk to the viscosity in the BL. Our MHD simulations have a dimensionless viscosity (α) in the BL that is at least a factor of ˜100 smaller than that in the disk. We discuss the implications of these results for BL dynamics and emission.

Polar motion interpretation using gravimetric observations

NASA Astrophysics Data System (ADS)

Seoane, L.; Bizouard, C.; Gambis, D.

2008-04-01

Polar motion is interpreted as the effect of i) the Earth’s inertia moment changes asso- ciated with the so-called mass term of the Earth’s angular momentum ii) the Earth’s relative angular momentum in the terrestrial frame. Thanks to the GRACE mission and in a lesser extent to LAGEOS missions, the mass term is determined since 2002, independently from any geophysical model. Besides the modeled excitations of the polar motion, i.e the atmospheric angular momentum (AAM), the Oceanic Angular Momentum (OAM), the Hydrological Angular Momentum (HAM), this gravimetric mass term is a new kind of information which can be matched to the observed excitation of the polar motion after removal of the effect of the relative angular momentum, mostly caused by the wind and the oceanic cur- rents. Such comparison, already performed by various authors, is updated for the last releases (RL04) of the gravity field changes i.e. those of the GFZ, CSR, JPL and explored for the mixed LAGEOS-GRACE solution of the GRGS. We confirm that a fair general agreement, especially for the y-component of the equatorial excitation. After removing the modeled oceanic and atmospheric excitations from the signals, we obtain the non-modeled excitation, mostly of hydrological nature; this allows us to compare them to the existing hydrological models, differences might comes from others Earth’s phenomena, for example, earthquakes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Kun; Li, Xiang-Dong, E-mail: lixd@nju.edu.cn

Millisecond pulsars (MSPs) are thought to originate from low-mass X-ray binaries (LMXBs). The discovery of eclipsing radio MSPs, including redbacks and black widows, indicates that evaporation of the donor star by the MSP’s irradiation takes place during the LMXB evolution. In this work, we investigate the effect of donor evaporation on the secular evolution of LMXBs, considering different evaporation efficiencies and related angular momentum loss. We find that for widening LMXBs, the donor star leaves a less massive white dwarf than without evaporation; for contracting systems, evaporation can speed up the evolution, resulting in dynamically unstable mass transfer and possiblymore » the formation of isolated MSPs.« less

How do external companions affect spin-orbit misalignment of hot Jupiters?

NASA Astrophysics Data System (ADS)

Lai, Dong; Anderson, Kassandra R.; Pu, Bonan

2018-04-01

Consider a planet with its orbital angular momentum axis aligned with the spin axis of its host star. To what extent does an inclined distant companion (giant planet or binary star) affect this alignment? We provide an analytic, quantitative answer and apply it to hot Jupiter systems, for which misalignments between the orbital axis and the stellar spin axis have been detected. We also show how similar consideration can be applied to multiplanet systems with distant companions (such as Kepler-56). The result of this paper provides a simple method to assess the dynamical role played by external companions on spin-orbit misalignments in exoplanetary systems.

Gas Accretion and Angular Momentum

NASA Astrophysics Data System (ADS)

Stewart, Kyle R.

In this chapter, we review the role of gas accretion to the acquisition of angular momentum, both in galaxies and in their gaseous halos. We begin by discussing angular momentum in dark matter halos, with a brief review of tidal torque theory and the importance of mergers, followed by a discussion of the canonical picture of galaxy formation within this framework, where halo gas is presumed to shock-eat to the virial temperature of the halo, following the same spin distribution as the dark matter halo before cooling to the center of the halo to form a galaxy there. In the context of recent observational evidence demonstrating the presence of high angular momentum gas in galaxy halos, we review recent cosmological hydrodynamic simulations that have begun to emphasize the role of "cold flow" accretion—anisotropic gas accretion along cosmic filaments that does not shock-heat before sinking to the central galaxy. We discuss the implications of these simulations, reviewing a number of recent developments in the literature, and suggest a revision to the canonical model as it relates to the expected angular momentum content of gaseous halos around galaxies.

Orbit-induced localized spin angular momentum in strong focusing of optical vectorial vortex beams

NASA Astrophysics Data System (ADS)

Li, Manman; Cai, Yanan; Yan, Shaohui; Liang, Yansheng; Zhang, Peng; Yao, Baoli

2018-05-01

Light beams may carry optical spin or orbital angular momentum, or both. The spin and orbital parts manifest themselves by the ellipticity of the state of polarization and the vortex structure of phase of light beams, separately. Optical spin and orbit interaction, arising from the interaction between the polarization and the spatial structure of light beams, has attracted enormous interest recently. The optical spin-to-orbital angular momentum conversion under strong focusing is well known, while the converse process, orbital-to-spin conversion, has not been reported so far. In this paper, we predict in theory that the orbital angular momentum can induce a localized spin angular momentum in strong focusing of a spin-free azimuthal polarization vortex beam. This localized longitudinal spin of the focused field can drive the trapped particle to spin around its own axis. This investigation provides a new degree of freedom for spinning particles by using a vortex phase, which may have considerable potentials in optical spin and orbit interaction, light-beam shaping, or optical manipulation.

Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexeyev, C. N.; Volyar, A. V.; Yavorsky, M. A.

We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over themore » array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.« less

H and H2 NMR properties in amorphous hydrogenated silicon (a-Si:H)

NASA Astrophysics Data System (ADS)

Lee, Sook

1986-07-01

It is shown that the basic NMR properties of ortho-H2 molecules with a rotational angular momentum J and a spin angular momentum I under the influence of a completely asymmetric crystalline field in an amorphous matrix can be described by an effective nuclear spin Hamiltonian which contains only the nuclear spin angular momentum operators (Ii), but is independent of the molecular rotational angular momentum operators (Ji). By directly applying the existing magnetic-resonance theories to this effective nuclear spin Hamiltonian, a simple description is presented for various static and dynamic NMR properties of the ortho-H2 NMR centers in amorphous hydrogenated silicon (a-Si:H), thereby resolving many difficulties and uncertainties encountered in understanding and explaining the H and H2 NMR observations in a-Si:H.

Arbitrary spin-to-orbital angular momentum conversion of light

NASA Astrophysics Data System (ADS)

Devlin, Robert C.; Ambrosio, Antonio; Rubin, Noah A.; Mueller, J. P. Balthasar; Capasso, Federico

2017-11-01

Optical elements that convert the spin angular momentum (SAM) of light into vortex beams have found applications in classical and quantum optics. These elements—SAM-to-orbital angular momentum (OAM) converters—are based on the geometric phase and only permit the conversion of left- and right-circular polarizations (spin states) into states with opposite OAM. We present a method for converting arbitrary SAM states into total angular momentum states characterized by a superposition of independent OAM. We designed a metasurface that converts left- and right-circular polarizations into states with independent values of OAM and designed another device that performs this operation for elliptically polarized states. These results illustrate a general material-mediated connection between SAM and OAM of light and may find applications in producing complex structured light and in optical communication.

LUT Reveals a New Mass-transferring Semi-detached Binary

NASA Astrophysics Data System (ADS)

Qian, S.-B.; Zhou, X.; Zhu, L.-Y.; Zejda, M.; Soonthornthum, B.; Zhao, E.-G.; Zhang, J.; Zhang, B.; Liao, W.-P.

2015-12-01

GQ Dra is a short-period eclipsing binary in a double stellar system that was discovered by Hipparcos. Complete light curves in the UV band were obtained with the Lunar-based Ultraviolet Telescope in 2014 November and December. Photometric solutions are determined using the W-D (Wilson and Devinney) method. It is discovered that GQ Dra is a classical Algol-type semi-detached binary where the secondary component is filling the critical Roche lobe. An analysis of all available times of minimum light suggests that the orbital period is increasing continuously at a rate of \\dot{P}=+3.48(+/- 0.23)× {10}-7 days yr-1. This could be explained by mass transfer from the secondary to the primary, which is in agreement with the semi-detached configuration with a lobe-filling secondary. By assuming a conservation of mass and angular momentum, the mass transfer rate is estimated as \\dot{m}=9.57(+/- 0.63)× {10}-8 {M}⊙ {{yr}}-1. All of these results reveal that GQ Dra is a mass-transferring semi-detached binary in a double system that was formed from an initially detached binary star. After the massive primary evolves to fill the critical Roche lobe, the mass transfer will be reversed and the binary will evolve into a contact configuration with two sub-giant or giant component stars.

Impact of Bayesian Priors on the Characterization of Binary Black Hole Coalescences

NASA Astrophysics Data System (ADS)

Vitale, Salvatore; Gerosa, Davide; Haster, Carl-Johan; Chatziioannou, Katerina; Zimmerman, Aaron

2017-12-01

In a regime where data are only mildly informative, prior choices can play a significant role in Bayesian statistical inference, potentially affecting the inferred physics. We show this is indeed the case for some of the parameters inferred from current gravitational-wave measurements of binary black hole coalescences. We reanalyze the first detections performed by the twin LIGO interferometers using alternative (and astrophysically motivated) prior assumptions. We find different prior distributions can introduce deviations in the resulting posteriors that impact the physical interpretation of these systems. For instance, (i) limits on the 90% credible interval on the effective black hole spin χeff are subject to variations of ˜10 % if a prior with black hole spins mostly aligned to the binary's angular momentum is considered instead of the standard choice of isotropic spin directions, and (ii) under priors motivated by the initial stellar mass function, we infer tighter constraints on the black hole masses, and in particular, we find no support for any of the inferred masses within the putative mass gap M ≲5 M⊙.

Impact of Bayesian Priors on the Characterization of Binary Black Hole Coalescences.

PubMed

Vitale, Salvatore; Gerosa, Davide; Haster, Carl-Johan; Chatziioannou, Katerina; Zimmerman, Aaron

2017-12-22

In a regime where data are only mildly informative, prior choices can play a significant role in Bayesian statistical inference, potentially affecting the inferred physics. We show this is indeed the case for some of the parameters inferred from current gravitational-wave measurements of binary black hole coalescences. We reanalyze the first detections performed by the twin LIGO interferometers using alternative (and astrophysically motivated) prior assumptions. We find different prior distributions can introduce deviations in the resulting posteriors that impact the physical interpretation of these systems. For instance, (i) limits on the 90% credible interval on the effective black hole spin χ_{eff} are subject to variations of ∼10% if a prior with black hole spins mostly aligned to the binary's angular momentum is considered instead of the standard choice of isotropic spin directions, and (ii) under priors motivated by the initial stellar mass function, we infer tighter constraints on the black hole masses, and in particular, we find no support for any of the inferred masses within the putative mass gap M≲5  M_{⊙}.

A Universal Angular Momentum Profile for Dark Matter Halos

NASA Astrophysics Data System (ADS)

Liao, Shihong; Chen, Jianxiong; Chu, M.-C.

2017-07-01

The angular momentum distribution in dark matter halos and galaxies is a key ingredient in understanding their formation. Specifically, the internal distribution of angular momenta is closely related to the formation of disk galaxies. In this article, we use halos identified from a high-resolution simulation, the Bolshoi simulation, to study the spatial distribution of specific angular momenta, j(r,θ ). We show that by stacking halos with similar masses to increase the signal-to-noise ratio, the profile can be fitted as a simple function, j{(r,θ )={j}s{\\sin }2{(θ /{θ }s)(r/{r}s)}2/(1+r/{r}s)}4, with three free parameters, {j}s,{r}s, and {θ }s. Specifically, j s correlates with the halo mass M vir as {j}s\\propto {M}{vir}2/3, r s has a weak dependence on the halo mass as {r}s\\propto {M}{vir}0.040, and {θ }s is independent of M vir. This profile agrees with that from a rigid shell model, though its origin is unclear. Our universal specific angular momentum profile j(r,θ ) is useful in modeling the angular momenta of halos. Furthermore, by using an empirical stellar mass-halo mass relation, we can infer the average angular momentum distribution of a dark matter halo. The specific angular momentum-stellar mass relation within a halo computed from our profile is shown to share a similar shape as that from the observed disk galaxies.

Helicons in uniform fields. II. Poynting vector and angular momenta

NASA Astrophysics Data System (ADS)

Stenzel, R. L.; Urrutia, J. M.

2018-03-01

The orbital and spin angular momenta of helicon modes have been determined quantitatively from laboratory experiments. The current density is obtained unambiguously from three dimensional magnetic field measurements. The only approximation made is to obtain the electric field from Hall Ohm's law which is usually the case for low frequency whistler modes. This allows the evaluation of the Poynting vector from which the angular momentum is obtained. Comparing two helicon modes (m = 0 and m = 1), one can separate the contribution of angular momentum of a rotating and non-rotating wave field. The orbital angular momentum is important to assess the wave-particle interaction by the transverse Doppler shift of rotating waves which has not been considered so far.

Penrose-like inequality with angular momentum for minimal surfaces

NASA Astrophysics Data System (ADS)

Anglada, Pablo

2018-02-01

In axially symmetric spacetimes the Penrose inequality can be strengthened to include angular momentum. We prove a version of this inequality for minimal surfaces, more precisely, a lower bound for the ADM mass in terms of the area of a minimal surface, the angular momentum and a particular measure of the surface size. We consider axially symmetric and asymptotically flat initial data, and use the monotonicity of the Geroch quasi-local energy on 2-surfaces along the inverse mean curvature flow.

A Very Fast and Angular Momentum Conserving Tree Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marcello, Dominic C., E-mail: dmarce504@gmail.com

There are many methods used to compute the classical gravitational field in astrophysical simulation codes. With the exception of the typically impractical method of direct computation, none ensure conservation of angular momentum to machine precision. Under uniform time-stepping, the Cartesian fast multipole method of Dehnen (also known as the very fast tree code) conserves linear momentum to machine precision. We show that it is possible to modify this method in a way that conserves both angular and linear momenta.

Crustal entrainment and pulsar glitches.

PubMed

Chamel, N

2013-01-04

Large pulsar frequency glitches are generally interpreted as sudden transfers of angular momentum between the neutron superfluid permeating the inner crust and the rest of the star. Despite the absence of viscous drag, the neutron superfluid is strongly coupled to the crust due to nondissipative entrainment effects. These effects are shown to severely limit the maximum amount of angular momentum that can possibly be transferred during glitches. In particular, it is found that the glitches observed in the Vela pulsar require an additional reservoir of angular momentum.

Bell’s measure and implementing quantum Fourier transform with orbital angular momentum of classical light

PubMed Central

Song, Xinbing; Sun, Yifan; Li, Pengyun; Qin, Hongwei; Zhang, Xiangdong

2015-01-01

We perform Bell’s measurement for the non-separable correlation between polarization and orbital angular momentum from the same classical vortex beam. The violation of Bell’s inequality for such a non-separable classical correlation has been demonstrated experimentally. Based on the classical vortex beam and non-quantum entanglement between the polarization and the orbital angular momentum, the Hadamard gates and conditional phase gates have been designed. Furthermore, a quantum Fourier transform has been implemented experimentally. PMID:26369424

On the small-x behavior of the orbital angular momentum distributions in QCD

NASA Astrophysics Data System (ADS)

Hatta, Yoshitaka; Yang, Dong-Jing

2018-06-01

We present the numerical solution of the leading order QCD evolution equation for the orbital angular momentum distributions of quarks and gluons and discuss its implications for the nucleon spin sum rule. We observe that at small-x, the gluon helicity and orbital angular momentum distributions are roughly of the same magnitude but with opposite signs, indicating a significant cancellation between them. A similar cancellation occurs also in the quark sector. We explain analytically the reason for this cancellation.

Diagnostic Studies with GLA Fields

NASA Technical Reports Server (NTRS)

Salstein, David A.

1997-01-01

Assessments of the NASA Goddard Earth Observing System-1 Data Assimilation System(GEOS-1 DAS), regarding heating rates, energetics, and angular momentum quantities were made. These diagnostics can be viewed as measures of climate variability. Comparisons with the NOAA/NCEP reanalysis system of momentum and energetics diagnostics are included. Water vapor and angular momentum are diagnosed in many models, including those of NASA, as part of the Atmospheric Model Intercomparison Project. 'Me GEOS-I and NOAA/NCEP global atmospheric angular momentum values are coherent on time scales down to about three days. Furthermore, they agree with the series of Earth angular momentum, as measured by tiny fluctuations in the rotation rate of the Earth, as variations in the length of day. The torques that effect such changes in atmospheric and Earth momentum are dominated by the influence of particular mountain systems, including the Rockies, Himalayas, and Andes, upon mountain torques on time scales shorter than about two weeks. Other project areas included collaboration with Goddard Space Flight Center to examine the impact of mountainous areas and the treatments of parameterizations on diagnoses of the atmosphere. Relevant preprints are included herein.

Binary black hole coalescence in the large-mass-ratio limit: The hyperboloidal layer method and waveforms at null infinity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernuzzi, Sebastiano; Nagar, Alessandro; Zenginoglu, Anil

2011-10-15

We compute and analyze the gravitational waveform emitted to future null infinity by a system of two black holes in the large-mass-ratio limit. We consider the transition from the quasiadiabatic inspiral to plunge, merger, and ringdown. The relative dynamics is driven by a leading order in the mass ratio, 5PN-resummed, effective-one-body (EOB), analytic-radiation reaction. To compute the waveforms, we solve the Regge-Wheeler-Zerilli equations in the time-domain on a spacelike foliation, which coincides with the standard Schwarzschild foliation in the region including the motion of the small black hole, and is globally hyperboloidal, allowing us to include future null infinity inmore » the computational domain by compactification. This method is called the hyperboloidal layer method, and is discussed here for the first time in a study of the gravitational radiation emitted by black hole binaries. We consider binaries characterized by five mass ratios, {nu}=10{sup -2,-3,-4,-5,-6}, that are primary targets of space-based or third-generation gravitational wave detectors. We show significative phase differences between finite-radius and null-infinity waveforms. We test, in our context, the reliability of the extrapolation procedure routinely applied to numerical relativity waveforms. We present an updated calculation of the final and maximum gravitational recoil imparted to the merger remnant by the gravitational wave emission, v{sub kick}{sup end}/(c{nu}{sup 2})=0.04474{+-}0.00007 and v{sub kick}{sup max}/(c{nu}{sup 2})=0.05248{+-}0.00008. As a self-consistency test of the method, we show an excellent fractional agreement (even during the plunge) between the 5PN EOB-resummed mechanical angular momentum loss and the gravitational wave angular momentum flux computed at null infinity. New results concerning the radiation emitted from unstable circular orbits are also presented. The high accuracy waveforms computed here could be considered for the construction of template banks or for calibrating analytic models such as the effective-one-body model.« less

Gravitational interactions of stars with supermassive black hole binaries. I. Tidal disruption events

NASA Astrophysics Data System (ADS)

Darbha, Siva; Coughlin, Eric R.; Kasen, Daniel; Quataert, Eliot

2018-04-01

Stars approaching supermassive black holes (SMBHs) in the centers of galaxies can be torn apart by strong tidal forces. We study the physics of tidal disruption by a circular, binary SMBH as a function of the binary mass ratio q = M2/M1 and separation a, exploring a large set of points in the parameter range q ∈ [0.01, 1] and a/rt1 ∈ [10, 1000]. We simulate encounters in which field stars approach the binary from the loss cone on parabolic, low angular momentum orbits. We present the rate of disruption and the orbital properties of the disrupted stars, and examine the fallback dynamics of the post-disruption debris in the "frozen-in" approximation. We conclude by calculating the time-dependent disruption rate over the lifetime of the binary. Throughout, we use a primary mass M1 = 106M⊙ as our central example. We find that the tidal disruption rate is a factor of ˜2 - 7 times larger than the rate for an isolated BH, and is independent of q for q ≳ 0.2. In the "frozen-in" model, disruptions from close, nearly equal mass binaries can produce intense tidal fallbacks: for binaries with q ≳ 0.2 and a/rt1 ˜ 100, roughly ˜18 - 40% of disruptions will have short rise times (trise ˜ 1 - 10 d) and highly super-Eddington peak return rates (\\dot{M}_{peak} / \\dot{M}_{Edd} ˜ 2 × 10^2 - 3 × 10^3).

The Spot Variability and Related Brightness variations of the Solar Type PreContact W UMa Binary System V1001 Cas

NASA Astrophysics Data System (ADS)

Samec, Ronald George; Koenke, Sam S.; Faulkner, Danny R.

2015-08-01

A new classification of eclipsing binary has emerged, Pre Contact WUMa Binaries (PCWB’s, Samec et al. 2012). These solar-type systems are usually detached or semidetached with one or both components under filling their critical Roche lobes. They usually have EA or EB-type light curves (unequal eclipse depths, indicating components with substantially different temperatures). The accepted scenario for these W UMa binaries is that they are undergoing steady but slow angular momentum losses due to magnetic braking as stellar winds blow radially away on stiff bipolar field lines. These binaries are believed to come into stable contact and eventually coalesce into blue straggler type, single, fast rotating A-type stars (Guinan and Bradstreet,1988). High precision 2012 and 2009 light curves are compared for the very short period (~0.43d) Precontact W UMa Binary (PCWB), V1001 Cassiopeia. This is the shortest period PCWB found so far. Its short period, similar to the majority of W UMa’s, in contrast to its distinct Algol-type light curve, make it a very rare and interesting system. Our solutions of light curves separated by some three years give approximately the same physical parameters. However the spots radically change, in temperature, area and position causing a distinctive variation in the shape of the light curves. We conclude that spots are very active on this solar type dwarf system and that it may mimic its larger cousins, the RS CVn binaries.

Gravitational interactions of stars with supermassive black hole binaries - I. Tidal disruption events

NASA Astrophysics Data System (ADS)

Darbha, Siva; Coughlin, Eric R.; Kasen, Daniel; Quataert, Eliot

2018-07-01

Stars approaching supermassive black holes (SMBHs) in the centres of galaxies can be torn apart by strong tidal forces. We study the physics of tidal disruption by a circular, binary SMBH as a function of the binary mass ratio q = M2/M1 and separation a, exploring a large set of points in the parameter range q ∈ [0.01, 1] and a/rt1 ∈ [10, 1000]. We simulate encounters in which field stars approach the binary from the loss cone on parabolic, low angular momentum orbits. We present the rate of disruption and the orbital properties of the disrupted stars, and examine the fallback dynamics of the post-disruption debris in the `frozen-in' approximation. We conclude by calculating the time-dependent disruption rate over the lifetime of the binary. Throughout, we use a primary mass M1 = 106 M⊙ as our central example. We find that the tidal disruption rate is a factor of ˜2-7 times larger than the rate for an isolated BH, and is independent of q for q ≳ 0.2. In the `frozen-in' model, disruptions from close, nearly equal mass binaries can produce intense tidal fallbacks: for binaries with q ≳ 0.2 and a/rt1 ˜ 100, roughly {˜ } 18-40 per cent of disruptions will have short rise times (trise ˜ 1-10 d) and highly super-Eddington peak return rates (\\dot{M}_peak / \\dot{M}_Edd ˜ 2 × 10^2-3 × 10^3).

Nonequilibrium life-cycles in Ocean Heat Content

NASA Astrophysics Data System (ADS)

Weiss, Jeffrey B.; Fox-Kemper, Baylor; Mandal, Dibyendu; Zia, Royce K. P.

2014-03-01

Natural climate variability can be considered as fluctuations in a nonequilibrium steady state. A fundamental property of nonequilibrium steady states is the phase space current which provides a preferred direction for fluctuations, and is manifested as preferred life-cycles for climate fluctuations. We propose a new quantity, the phase space angular momentum, to quantify the phase space rotation. In analogy with traditional angular momentum, which quantifies the rotation of mass in physical space, the phase space angular momentum quantifies the rotation of probability in phase space. It has the additional advantage that it is straightforward to calculate from a time series. We investigate the phase space angular momentum for fluctuations in ocean heat content in both observations and ocean general circulation models. We gratefully acknowledge financial support from the National Science Foundation (USA) under grant OCE 1245944.

Chiral resolution of spin angular momentum in linearly polarized and unpolarized light

PubMed Central

Hernández, R. J.; Mazzulla, A.; Provenzano, C.; Pagliusi, P.; Cipparrone, G.

2015-01-01

Linearly polarized (LP) and unpolarized (UP) light are racemic entities since they can be described as superposition of opposite circularly polarized (CP) components of equal amplitude. As a consequence they do not carry spin angular momentum. Chiral resolution of a racemate, i.e. separation of their chiral components, is usually performed via asymmetric interaction with a chiral entity. In this paper we provide an experimental evidence of the chiral resolution of linearly polarized and unpolarized Gaussian beams through the transfer of spin angular momentum to chiral microparticles. Due to the interplay between linear and angular momentum exchange, basic manipulation tasks, as trapping, spinning or orbiting of micro-objects, can be performed by light with zero helicity. The results might broaden the perspectives for development of miniaturized and cost-effective devices. PMID:26585284

Galaxy spin as a formation probe: the stellar-to-halo specific angular momentum relation

NASA Astrophysics Data System (ADS)

Posti, Lorenzo; Pezzulli, Gabriele; Fraternali, Filippo; Di Teodoro, Enrico M.

2018-03-01

We derive the stellar-to-halo specific angular momentum relation (SHSAMR) of galaxies at z = 0 by combining (i) the standard Λcold dark matter tidal torque theory, (ii) the observed relation between stellar mass and specific angular momentum (the Fall relation), and (iii) various determinations of the stellar-to-halo mass relation (SHMR). We find that the ratio fj = j*/jh of the specific angular momentum of stars to that of the dark matter (i) varies with mass as a double power law, (ii) always has a peak in the mass range explored and iii) is three to five times larger for spirals than for ellipticals. The results have some dependence on the adopted SHMR and we provide fitting formulae in each case. For any choice of the SHMR, the peak of fj occurs at the same mass where the stellar-to-halo mass ratio f* = M*/Mh has a maximum. This is mostly driven by the straightness and tightness of the Fall relation, which requires fj and f* to be correlated with each other roughly as f_j∝ f_\\ast ^{2/3}, as expected if the outer and more angular momentum rich parts of a halo failed to accrete on to the central galaxy and form stars (biased collapse). We also confirm that the difference in the angular momentum of spirals and ellipticals at a given mass is too large to be ascribed only to different spins of the parent dark-matter haloes (spin bias).

Cosmic Vorticity and the Origin Halo Spins

NASA Astrophysics Data System (ADS)

Libeskind, Noam I.; Hoffman, Yehuda; Steinmetz, Matthias; Gottlöber, Stefan; Knebe, Alexander; Hess, Steffen

2013-04-01

In the standard model of cosmology, structure emerges out of a non-rotational flow and the angular momentum of collapsing halos is induced by tidal torques. The growth of angular momentum in the linear and quasi-linear phases is associated with a shear, curl-free, flow and it is well described within the linear framework of tidal torque theory (TTT). However, TTT ceases to be applicable as halos approach turnaround when their ambient flow field becomes rotational. Subsequently, halos become embedded in a vortical flow field and the growth of their angular momentum is affected by the vorticity of their ambient velocity field. Using a cosmological simulation, we have examined the importance of the curl of the velocity field in determining halo spin, finding a significant alignment between the two: the vorticity tends to be perpendicular to the axis of the fastest collapse of the velocity shear tensor (e 1). This is independent of halo masses and cosmic web environment. Our results agree with previous findings on the tendency of halo spin to be perpendicular to e 1, and of the spin of (simulated) halos and (observed) galaxies to be aligned with the large-scale structure. It follows that angular momentum growth proceeds in two distinct phases. First, the angular momentum emerges out of a shear, curl-free, potential flow, as described by TTT. In the second phase, in which halos approach virialization, the angular momentum emerges out of a vortical flow and halo spin becomes partially aligned with the vorticity of the ambient flow field.

Effects of anisotropic electron-ion interactions in atomic photoelectron angular distributions

NASA Technical Reports Server (NTRS)

Dill, D.; Starace, A. F.; Manson, S. T.

1974-01-01

The photoelectron asymmetry parameter beta in LS-coupling is obtained as an expansion into contributions from alternative angular momentum transfers j sub t. The physical significance of this expansion of beta is shown to be that: (1) the electric dipole interaction transfers to the atom a charcteristic single angular momentum j sub t = sub o, where sub o is the photoelectron's initial orbital momentum; and (2) angular momentum transfers indicate the presence of anisotropic interaction of the outgoing photoelectron with the residual ion. For open shell atoms the photoelectron-ion interaction is generally anisotropic; photoelectron phase shifts and electric dipole matrix elements depend on both the multiplet term of the residual ion and the total orbital momentum of the ion-photoelectron final state channel. Consequently beta depends on the term levels of the residual ion and contains contributions from all allowed values of j sub t. Numerical calculations of the asymmetry parameters and partial cross sections for photoionization of atomic sulfur are presented.

The azimuthal component of Poynting's vector and the angular momentum of light

NASA Astrophysics Data System (ADS)

Cameron, Robert P.; Speirits, Fiona C.; Gilson, Claire R.; Allen, L.; Barnett, Stephen M.

2015-12-01

The usual description in basic electromagnetic theory of the linear and angular momenta of light is centred upon the identification of Poynting's vector as the linear momentum density and its cross product with position, or azimuthal component, as the angular momentum density. This seemingly reasonable approach brings with it peculiarities, however, in particular with regards to the separation of angular momentum into orbital and spin contributions, which has sometimes been regarded as contrived. In the present paper, we observe that densities are not unique, which leads us to ask whether the usual description is, in fact, the most natural choice. To answer this, we adopt a fundamental rather than heuristic approach by first identifying appropriate symmetries of Maxwell's equations and subsequently applying Noether's theorem to obtain associated conservation laws. We do not arrive at the usual description. Rather, an equally acceptable one in which the relationship between linear and angular momenta is nevertheless more subtle and in which orbital and spin contributions emerge separately and with transparent forms.

Angular momentum transport with twisted exciton wave packets

NASA Astrophysics Data System (ADS)

Zang, Xiaoning; Lusk, Mark T.

2017-10-01

A chain of cofacial molecules with CN or CN h symmetry supports excitonic states with a screwlike structure. These can be quantified with the combination of an axial wave number and an azimuthal winding number. Combinations of these states can be used to construct excitonic wave packets that spiral down the chain with well-determined linear and angular momenta. These twisted exciton wave packets can be created and annihilated using laser pulses, and their angular momentum can be optically modified during transit. This allows for the creation of optoexcitonic circuits in which information, encoded in the angular momentum of light, is converted into excitonic wave packets that can be manipulated, transported, and then reemitted. A tight-binding paradigm is used to demonstrate the key ideas. The approach is then extended to quantify the evolution of twisted exciton wave packets in a many-body, multilevel time-domain density functional theory setting. In both settings, numerical methods are developed that allow the site-to-site transfer of angular momentum to be quantified.

Rapid Jet Precession During the 2015 Outburst of the Black Hole X-ray Binary V404 Cygni

NASA Astrophysics Data System (ADS)

Sivakoff, Gregory R.; Miller-Jones, James; Tetarenko, Alex J.

2017-08-01

In stellar-mass black holes that are orbited by lower-mass companions (black hole low-mass X-ray binaries), the accretion process can undergo dramatic outbursts that can be accompanied by the launching of powerful relativistic jets. We still do not know the exact mechanism responsible for launching these jets, despite decades of research and the importance of determining this mechanism given the clear analogue of accreting super-massive black holes and their jets. The two main models for launching jets involve the extraction of the rotational energy of a spinning black hole (Blandford-Znajek) and the centrifugal acceleration of particles by open magnetic field lines rotating with the accretion flow (Blandford-Payne). Since some relativistic jets are not fully aligned with the angular momentum of the binary's orbit, the inner accretion flow of some black hole X-ray binaries may precess due to frame-dragging by a spinning black hole (Lense-Thirring precession). This precession has been previously observed close to the black hole as second-timescale quasi-periodic (X-ray) variability. In this talk we will present radio-through-sub-mm timing and high-angular resolution radio imaging (including a high-timing resolution movie) of the black hole X-ray binary V404 Cygni during its 2015 outburst. These data show that at the peak of the outburst the relativistic jets in this system were precessing on timescales of hours. We will discuss how rapid precession can be explained by Lense-Thirring precession of a vertically-extended slim disc that is maintained out to a radius of 6 X 1010 cm by a highly super-Eddington accretion rate. This would imply that the jet axis of V404 Cyg is not aligned with the black hole spin. More importantly, this places a key requirement on any model for launching jets, and may favour launching the jet from the rotating magnetic fields threading the disc.

Angular momentum of phonons and its application to single-spin relaxation

NASA Astrophysics Data System (ADS)

Nakane, Jotaro J.; Kohno, Hiroshi

2018-05-01

We reexamine the relaxation process of a single spin embedded in an elastic medium, a problem studied recently by Garanin and Chudnovsky (GC) [Phys. Rev. B 92, 024421 (2015), 10.1103/PhysRevB.92.024421] from the viewpoint of angular-momentum transfer. Using Noether's theorem, we identify two distinct angular momenta of the medium, one Newtonian discussed by GC and the other field-theoretical, both of which consist of an orbital part and a spin part. For both angular momenta, we found that the orbital part is as essential as the spin part in the relaxation process. In particular, the angular-momentum transfer from the (real) spin to the Newtonian orbital part may be considered as an incipient rotation that leads to the Einstein-de Haas effect.

Rotation of Giant Stars

NASA Astrophysics Data System (ADS)

Kissin, Yevgeni; Thompson, Christopher

2015-07-01

The internal rotation of post-main sequence stars is investigated, in response to the convective pumping of angular momentum toward the stellar core, combined with a tight magnetic coupling between core and envelope. The spin evolution is calculated using model stars of initial mass 1, 1.5, and 5 {M}⊙ , taking into account mass loss on the giant branches. We also include the deposition of orbital angular momentum from a sub-stellar companion, as influenced by tidal drag along with the excitation of orbital eccentricity by a fluctuating gravitational quadrupole moment. A range of angular velocity profiles {{Ω }}(r) is considered in the envelope, extending from solid rotation to constant specific angular momentum. We focus on the backreaction of the Coriolis force, and the threshold for dynamo action in the inner envelope. Quantitative agreement with measurements of core rotation in subgiants and post-He core flash stars by Kepler is obtained with a two-layer angular velocity profile: uniform specific angular momentum where the Coriolis parameter {Co}\\equiv {{Ω }}{τ }{con}≲ 1 (here {τ }{con} is the convective time), and {{Ω }}(r)\\propto {r}-1 where {Co}≳ 1. The inner profile is interpreted in terms of a balance between the Coriolis force and angular pressure gradients driven by radially extended convective plumes. Inward angular momentum pumping reduces the surface rotation of subgiants, and the need for a rejuvenated magnetic wind torque. The co-evolution of internal magnetic fields and rotation is considered in Kissin & Thompson, along with the breaking of the rotational coupling between core and envelope due to heavy mass loss.

Seismic evidence for the loss of stellar angular momentum before the white-dwarf stage.

PubMed

Charpinet, S; Fontaine, G; Brassard, P

2009-09-24

White-dwarf stars represent the final products of the evolution of some 95% of all stars. If stars were to keep their angular momentum throughout their evolution, their white-dwarf descendants, owing to their compact nature, should all rotate relatively rapidly, with typical periods of the order of a few seconds. Observations of their photospheres show, in contrast, that they rotate much more slowly, with periods ranging from hours to tens of years. It is not known, however, whether a white dwarf could 'hide' some of its original angular momentum below the superficial layers, perhaps spinning much more rapidly inside than at its surface. Here we report a determination of the internal rotation profile of a white dwarf using a method based on asteroseismology. We show that the pulsating white dwarf PG 1159-035 rotates as a solid body (encompassing more than 97.5% of its mass) with the relatively long period of 33.61 +/- 0.59 h. This implies that it has lost essentially all of its angular momentum, thus favouring theories which suggest important angular momentum transfer and loss in evolutionary phases before the white-dwarf stage.

Relativistic properties of a molecule: energy, linear momentum, angular momentum and boost momentum to order 1/c 2

NASA Astrophysics Data System (ADS)

Cameron, Robert P.; Cotter, J. P.

2018-05-01

We give an explicit and general description of the energy, linear momentum, angular momentum and boost momentum of a molecule to order 1/c 2, where it necessary to take account of kinetic contributions made by the electrons and nuclei as well as electromagnetic contributions made by the intramolecular field. A wealth of interesting subtleties are encountered that are not seen at order 1/c 0, including relativistic Hall shifts, anomalous velocities and hidden momenta. Some of these have well known analogues in solid state physics.

Time-resolved orbital angular momentum spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noyan, Mehmet A.; Kikkawa, James M.

We introduce pump-probe magneto-orbital spectroscopy, wherein Laguerre-Gauss optical pump pulses impart orbital angular momentum to the electronic states of a material and subsequent dynamics are studied with 100 fs time resolution. The excitation uses vortex modes that distribute angular momentum over a macroscopic area determined by the spot size, and the optical probe studies the chiral imbalance of vortex modes reflected off the sample. First observations in bulk GaAs yield transients that evolve on time scales distinctly different from population and spin relaxation, as expected, but with surprisingly large lifetimes.

The Mass and Angular Momentum Balance of the Zonally-Averaged Global Circulation.

DTIC Science & Technology

1981-01-01

2 2SFSf F SO~ ABSTRACT (0m-l n oerse~e side Ht moeoeei md fdeutly’ by Week now"*ee Li ATTACHED hO u 47 EDI TIo OP 1 NOV6 Ies OBSOLETE UNCLASS 82 09 28...eddies, and transient circulat.@ns, respec tively. rigeree 12 and 13 displa the vertical sad meridional distribution of relat’.ve angular momentum trass...the transient component is the dominant mode of angular momentum transport in January. It is poleward at virtually all latitudes in each hemisphere

Spatial distribution of angular momentum inside the nucleon

NASA Astrophysics Data System (ADS)

Lorcé, Cédric; Mantovani, Luca; Pasquini, Barbara

2018-01-01

We discuss in detail the spatial distribution of angular momentum inside the nucleon. We show that the discrepancies between different definitions originate from terms that integrate to zero. Even though these terms can safely be dropped at the integrated level, they have to be taken into account when discussing distributions. Using the scalar diquark model, we illustrate our results and, for the first time, check explicitly that the equivalence between kinetic and canonical orbital angular momentum persists at the level of distributions, as expected in a system without gauge degrees of freedom.

High accuracy fuel flowmeter

NASA Technical Reports Server (NTRS)

1986-01-01

All three flowmeter concepts (vortex, dual turbine, and angular momentum) were subjected to experimental and analytical investigation to determine the potential portotype performance. The three concepts were subjected to a comprehensive rating. Eight parameters of performance were evaluated on a zero-to-ten scale, weighted, and summed. The relative ratings of the vortex, dual turbine, and angular momentum flowmeters are 0.71, 1.00, and 0.95, respectively. The dual turbine flowmeter concept was selected as the primary candidate and the angular momentum flowmeter as the secondary candidate for prototype development and evaluation.

Bekenstein bounds, Penrose inequalities, and black hole formation

NASA Astrophysics Data System (ADS)

Jaracz, Jaroslaw S.; Khuri, Marcus A.

2018-06-01

A universal geometric inequality for bodies relating energy, size, angular momentum, and charge is naturally implied by Bekenstein's entropy bounds. We establish versions of this inequality for axisymmetric bodies satisfying appropriate energy conditions, thus lending credence to the most general form of Bekenstein's bound. Similar techniques are then used to prove a Penrose-like inequality in which the ADM energy is bounded from below in terms of horizon area, angular momentum, and charge. Lastly, new criteria for the formation of black holes is presented involving concentration of angular momentum, charge, and nonelectromagnetic matter energy.

Hunting the Gluon Orbital Angular Momentum at the Electron-Ion Collider.

PubMed

Ji, Xiangdong; Yuan, Feng; Zhao, Yong

2017-05-12

Applying the connection between the parton Wigner distribution and orbital angular momentum (OAM), we investigate the probe of the gluon OAM in hard scattering processes at the planned electron-ion collider. We show that the single longitudinal target-spin asymmetry in the hard diffractive dijet production is very sensitive to the gluon OAM distribution. The associated spin asymmetry leads to a characteristic azimuthal angular correlation of sin(ϕ_{q}-ϕ_{Δ}), where ϕ_{Δ} and ϕ_{q} are the azimuthal angles of the proton momentum transfer and the relative transverse momentum between the quark-antiquark pair. This study may motivate a first measurement of the gluon OAM in the proton spin sum rule.

Symmetry and conservation laws in semiclassical wave packet dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohsawa, Tomoki, E-mail: tomoki@utdallas.edu

2015-03-15

We formulate symmetries in semiclassical Gaussian wave packet dynamics and find the corresponding conserved quantities, particularly the semiclassical angular momentum, via Noether’s theorem. We consider two slightly different formulations of Gaussian wave packet dynamics; one is based on earlier works of Heller and Hagedorn and the other based on the symplectic-geometric approach by Lubich and others. In either case, we reveal the symplectic and Hamiltonian nature of the dynamics and formulate natural symmetry group actions in the setting to derive the corresponding conserved quantities (momentum maps). The semiclassical angular momentum inherits the essential properties of the classical angular momentum asmore » well as naturally corresponds to the quantum picture.« less

Anisotropic kinetic energy release and gyroscopic behavior of CO2 super rotors from an optical centrifuge.

PubMed

Murray, Matthew J; Ogden, Hannah M; Mullin, Amy S

2017-10-21

An optical centrifuge is used to generate an ensemble of CO 2 super rotors with oriented angular momentum. The collision dynamics and energy transfer behavior of the super rotor molecules are investigated using high-resolution transient IR absorption spectroscopy. New multipass IR detection provides improved sensitivity to perform polarization-dependent transient studies for rotational states with 76 ≤ J ≤ 100. Polarization-dependent measurements show that the collision-induced kinetic energy release is spatially anisotropic and results from both near-resonant energy transfer between super rotor molecules and non-resonant energy transfer between super rotors and thermal molecules. J-dependent studies show that the extent and duration of the orientational anisotropy increase with rotational angular momentum. The super rotors exhibit behavior akin to molecular gyroscopes, wherein molecules with larger amounts of angular momentum are less likely to change their angular momentum orientation through collisions.

Anisotropic kinetic energy release and gyroscopic behavior of CO2 super rotors from an optical centrifuge

NASA Astrophysics Data System (ADS)

Murray, Matthew J.; Ogden, Hannah M.; Mullin, Amy S.

2017-10-01

An optical centrifuge is used to generate an ensemble of CO2 super rotors with oriented angular momentum. The collision dynamics and energy transfer behavior of the super rotor molecules are investigated using high-resolution transient IR absorption spectroscopy. New multipass IR detection provides improved sensitivity to perform polarization-dependent transient studies for rotational states with 76 ≤ J ≤ 100. Polarization-dependent measurements show that the collision-induced kinetic energy release is spatially anisotropic and results from both near-resonant energy transfer between super rotor molecules and non-resonant energy transfer between super rotors and thermal molecules. J-dependent studies show that the extent and duration of the orientational anisotropy increase with rotational angular momentum. The super rotors exhibit behavior akin to molecular gyroscopes, wherein molecules with larger amounts of angular momentum are less likely to change their angular momentum orientation through collisions.

Physical experience enhances science learning.

PubMed

Kontra, Carly; Lyons, Daniel J; Fischer, Susan M; Beilock, Sian L

2015-06-01

Three laboratory experiments involving students' behavior and brain imaging and one randomized field experiment in a college physics class explored the importance of physical experience in science learning. We reasoned that students' understanding of science concepts such as torque and angular momentum is aided by activation of sensorimotor brain systems that add kinetic detail and meaning to students' thinking. We tested whether physical experience with angular momentum increases involvement of sensorimotor brain systems during students' subsequent reasoning and whether this involvement aids their understanding. The physical experience, a brief exposure to forces associated with angular momentum, significantly improved quiz scores. Moreover, improved performance was explained by activation of sensorimotor brain regions when students later reasoned about angular momentum. This finding specifies a mechanism underlying the value of physical experience in science education and leads the way for classroom practices in which experience with the physical world is an integral part of learning. © The Author(s) 2015.

Fractional Fourier transform of Lorentz-Gauss vortex beams

NASA Astrophysics Data System (ADS)

Zhou, GuoQuan; Wang, XiaoGang; Chu, XiuXiang

2013-08-01

An analytical expression for a Lorentz-Gauss vortex beam passing through a fractional Fourier transform (FRFT) system is derived. The influences of the order of the FRFT and the topological charge on the normalized intensity distribution, the phase distribution, and the orbital angular momentum density of a Lorentz-Gauss vortex beam in the FRFT plane are examined. The order of the FRFT controls the beam spot size, the orientation of the beam spot, the spiral direction of the phase distribution, the spatial orientation of the two peaks in the orbital angular momentum density distribution, and the magnitude of the orbital angular momentum density. The increase of the topological charge not only results in the dark-hollow region becoming large, but also brings about detail changes in the beam profile. The spatial orientation of the two peaks in the orbital angular momentum density distribution and the phase distribution also depend on the topological charge.

Quantum simulation of 2D topological physics in a 1D array of optical cavities

PubMed Central

Luo, Xi-Wang; Zhou, Xingxiang; Li, Chuan-Feng; Xu, Jin-Shi; Guo, Guang-Can; Zhou, Zheng-Wei

2015-01-01

Orbital angular momentum of light is a fundamental optical degree of freedom characterized by unlimited number of available angular momentum states. Although this unique property has proved invaluable in diverse recent studies ranging from optical communication to quantum information, it has not been considered useful or even relevant for simulating nontrivial physics problems such as topological phenomena. Contrary to this misconception, we demonstrate the incredible value of orbital angular momentum of light for quantum simulation by showing theoretically how it allows to study a variety of important 2D topological physics in a 1D array of optical cavities. This application for orbital angular momentum of light not only reduces required physical resources but also increases feasible scale of simulation, and thus makes it possible to investigate important topics such as edge-state transport and topological phase transition in a small simulator ready for immediate experimental exploration. PMID:26145177

Geometrical optics of beams with vortices: Berry phase and orbital angular momentum Hall effect.

PubMed

Bliokh, Konstantin Yu

2006-07-28

We consider propagation of a paraxial beam carrying the spin angular momentum (polarization) and intrinsic orbital angular momentum (IOAM) in a smoothly inhomogeneous isotropic medium. It is shown that the presence of IOAM can dramatically enhance and rearrange the topological phenomena that previously were considered solely in connection to the polarization of transverse waves. In particular, the appearance of a new type of Berry phase that describes the parallel transport of the beam structure along a curved ray is predicted. We derive the ray equations demonstrating the splitting of beams with different values of IOAM. This is the orbital angular momentum Hall effect, which resembles the Magnus effect for optical vortices. Unlike the spin Hall effect of photons, it can be much larger in magnitude and is inherent to waves of any nature. Experimental means to detect the phenomena are discussed.

Tilted-axis wobbling in odd-mass nuclei

NASA Astrophysics Data System (ADS)

Budaca, R.

2018-02-01

A triaxial rotor Hamiltonian with a rigidly aligned high-j quasiparticle is treated by a time-dependent variational principle, using angular momentum coherent states. The resulting classical energy function has three unique critical points in a space of generalized conjugate coordinates, which can minimize the energy for specific ordering of the inertial parameters and a fixed angular momentum state. Because of the symmetry of the problem, there are only two unique solutions, corresponding to wobbling motion around a principal axis and, respectively, a tilted axis. The wobbling frequencies are obtained after a quantization procedure and then used to calculate E 2 and M 1 transition probabilities. The analytical results are employed in the study of the wobbling excitations of 135Pr nucleus, which is found to undergo a transition from low angular momentum transverse wobbling around a principal axis toward a tilted-axis wobbling at higher angular momentum.

Steering Law Controlling the Constant Speeds of Control Moment Gyros

NASA Astrophysics Data System (ADS)

KOYASAKO, Y.; TAKAHASHI, M.

2016-09-01

To enable the agile control of satellites, using control moment gyros (CMGs) has become increasingly necessary because of their ability to generate large amounts of torque. However, CMGs have a singularity problem whereby the torque by the CMGs degenerates from three dimensions to two dimensions, affecting spacecraft attitude control performance. This study proposes a new steering control law for CMGs by controlling the constant speed of a CMG. The proposed method enables agile attitude changes, according to the required task, by managing the total angular momentum of the CMGs by considering the distance to external singularities. In the proposed method, the total angular momentum is biased in a specific direction and the angular momentum envelope is extended. The design method can increase the net angular momentum of CMGs which can be exchanged with the satellite. The effectiveness of the proposed method is demonstrated by numerical simulations.

New dynamic variables for rotating spacecraft

NASA Technical Reports Server (NTRS)

Markley, F. Landis

1993-01-01

This paper introduces two new seven-parameter representations for spacecraft attitude dynamics modeling. The seven parameters are the three components of the total system angular momentum in the spacecraft body frame; the three components of the angular momentum in the inertial reference frame; and an angle variable. These obey a single constraint as do parameterizations that include a quaternion; in this case the constraint is the equality of the sum of the squares of the angular momentum components in the two frames. The two representations are nonsingular if the system angular momentum is non-zero and obeys certain orientation constraints. The new parameterizations of the attitude matrix, the equations of motion, and the relation of the solution of these equations to Euler angles for torque-free motion are developed and analyzed. The superiority of the new parameterizations for numerical integration is shown in a specific example.

Creating fractional quantum Hall states with atomic clusters using light-assisted insertion of angular momentum

NASA Astrophysics Data System (ADS)

Zhang, Junyi; Beugnon, Jerome; Nascimbene, Sylvain

We describe a protocol to prepare clusters of ultracold bosonic atoms in strongly interacting states reminiscent of fractional quantum Hall states. Our scheme consists in injecting a controlled amount of angular momentum to an atomic gas using Raman transitions carrying orbital angular momentum. By injecting one unit of angular momentum per atom, one realizes a single-vortex state, which is well described by mean-field theory for large enough particle numbers. We also present schemes to realize fractional quantum Hall states, namely, the bosonic Laughlin and Moore-Read states. We investigate the requirements for adiabatic nucleation of such topological states, in particular comparing linear Landau-Zener ramps and arbitrary ramps obtained from optimized control methods. We also show that this protocol requires excellent control over the isotropic character of the trapping potential. ERC-Synergy Grant UQUAM, ANR-10-IDEX-0001-02, DIM NanoK Atocirc project.

A parametric study of the behavior of the angular momentum vector during spin rate changes of rigid body spacecraft

NASA Technical Reports Server (NTRS)

Longuski, J. M.

1982-01-01

During a spin-up or spin-down maneuver of a spinning spacecraft, it is usual to have not only a constant body-fixed torque about the desired spin axis, but also small undesired constant torques about the transverse axes. This causes the orientation of the angular momentum vector to change in inertial space. Since an analytic solution is available for the angular momentum vector as a function of time, this behavior can be studied for large variations of the dynamic parameters, such as the initial spin rate, the inertial properties and the torques. As an example, the spin-up and spin-down maneuvers of the Galileo spacecraft was studied and as a result, very simple heuristic solutions were discovered which provide very good approximations to the parametric behavior of the angular momentum vector orientation.

Tunable orbital angular momentum in high-harmonic generation

PubMed Central

Gauthier, D.; Ribič, P. Rebernik; Adhikary, G.; Camper, A.; Chappuis, C.; Cucini, R.; DiMauro, L. F.; Dovillaire, G.; Frassetto, F.; Géneaux, R.; Miotti, P.; Poletto, L.; Ressel, B.; Spezzani, C.; Stupar, M.; Ruchon, T.; De Ninno, G.

2017-01-01

Optical vortices are currently one of the most intensively studied topics in optics. These light beams, which carry orbital angular momentum (OAM), have been successfully utilized in the visible and infrared in a wide variety of applications. Moving to shorter wavelengths may open up completely new research directions in the areas of optical physics and material characterization. Here, we report on the generation of extreme-ultraviolet optical vortices with femtosecond duration carrying a controllable amount of OAM. From a basic physics viewpoint, our results help to resolve key questions such as the conservation of angular momentum in highly nonlinear light–matter interactions, and the disentanglement and independent control of the intrinsic and extrinsic components of the photon's angular momentum at short-wavelengths. The methods developed here will allow testing some of the recently proposed concepts such as OAM-induced dichroism, magnetic switching in organic molecules and violation of dipolar selection rules in atoms. PMID:28378741

Quantum simulation of 2D topological physics in a 1D array of optical cavities.

PubMed

Luo, Xi-Wang; Zhou, Xingxiang; Li, Chuan-Feng; Xu, Jin-Shi; Guo, Guang-Can; Zhou, Zheng-Wei

2015-07-06

Orbital angular momentum of light is a fundamental optical degree of freedom characterized by unlimited number of available angular momentum states. Although this unique property has proved invaluable in diverse recent studies ranging from optical communication to quantum information, it has not been considered useful or even relevant for simulating nontrivial physics problems such as topological phenomena. Contrary to this misconception, we demonstrate the incredible value of orbital angular momentum of light for quantum simulation by showing theoretically how it allows to study a variety of important 2D topological physics in a 1D array of optical cavities. This application for orbital angular momentum of light not only reduces required physical resources but also increases feasible scale of simulation, and thus makes it possible to investigate important topics such as edge-state transport and topological phase transition in a small simulator ready for immediate experimental exploration.

Angular momentum projection for a Nilsson mean-field plus pairing model

NASA Astrophysics Data System (ADS)

Wang, Yin; Pan, Feng; Launey, Kristina D.; Luo, Yan-An; Draayer, J. P.

2016-06-01

The angular momentum projection for the axially deformed Nilsson mean-field plus a modified standard pairing (MSP) or the nearest-level pairing (NLP) model is proposed. Both the exact projection, in which all intrinsic states are taken into consideration, and the approximate projection, in which only intrinsic states with K = 0 are taken in the projection, are considered. The analysis shows that the approximate projection with only K = 0 intrinsic states seems reasonable, of which the configuration subspace considered is greatly reduced. As simple examples for the model application, low-lying spectra and electromagnetic properties of 18O and 18Ne are described by using both the exact and approximate angular momentum projection of the MSP or the NLP, while those of 20Ne and 24Mg are described by using the approximate angular momentum projection of the MSP or NLP.

Arbitrary spin-to-orbital angular momentum conversion of light.

PubMed

Devlin, Robert C; Ambrosio, Antonio; Rubin, Noah A; Mueller, J P Balthasar; Capasso, Federico

2017-11-17

Optical elements that convert the spin angular momentum (SAM) of light into vortex beams have found applications in classical and quantum optics. These elements-SAM-to-orbital angular momentum (OAM) converters-are based on the geometric phase and only permit the conversion of left- and right-circular polarizations (spin states) into states with opposite OAM. We present a method for converting arbitrary SAM states into total angular momentum states characterized by a superposition of independent OAM. We designed a metasurface that converts left- and right-circular polarizations into states with independent values of OAM and designed another device that performs this operation for elliptically polarized states. These results illustrate a general material-mediated connection between SAM and OAM of light and may find applications in producing complex structured light and in optical communication. Copyright © 2017, American Association for the Advancement of Science.

Extreme throat initial data set and horizon area-angular momentum inequality for axisymmetric black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dain, Sergio; Max Planck Institute for Gravitational Physics

2010-11-15

We present a formula that relates the variations of the area of extreme throat initial data with the variation of an appropriate defined mass functional. From this expression we deduce that the first variation, with fixed angular momentum, of the area is zero and the second variation is positive definite evaluated at the extreme Kerr throat initial data. This indicates that the area of the extreme Kerr throat initial data is a minimum among this class of data. And hence the area of generic throat initial data is bounded from below by the angular momentum. Also, this result strongly suggestsmore » that the inequality between area and angular momentum holds for generic asymptotically flat axially symmetric black holes. As an application, we prove this inequality in the nontrivial family of spinning Bowen-York initial data.« less

Extrasolar binary planets. I. Formation by tidal capture during planet-planet scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ochiai, H.; Nagasawa, M.; Ida, S., E-mail: nagasawa.m.ad@m.titech.ac.jp

2014-08-01

We have investigated (1) the formation of gravitationally bounded pairs of gas-giant planets (which we call 'binary planets') from capturing each other through planet-planet dynamical tide during their close encounters and (2) the subsequent long-term orbital evolution due to planet-planet and planet-star quasi-static tides. For the initial evolution in phase 1, we carried out N-body simulations of the systems consisting of three Jupiter-mass planets taking into account the dynamical tide. The formation rate of the binary planets is as much as 10% of the systems that undergo orbital crossing, and this fraction is almost independent of the initial stellarcentric semimajormore » axes of the planets, while ejection and merging rates sensitively depend on the semimajor axes. As a result of circularization by the planet-planet dynamical tide, typical binary separations are a few times the sum of the physical radii of the planets. After the orbital circularization, the evolution of the binary system is governed by long-term quasi-static tide. We analytically calculated the quasi-static tidal evolution in phase 2. The binary planets first enter the spin-orbit synchronous state by the planet-planet tide. The planet-star tide removes angular momentum of the binary motion, eventually resulting in a collision between the planets. However, we found that the binary planets survive the tidal decay for the main-sequence lifetime of solar-type stars (∼10 Gyr), if the binary planets are beyond ∼0.3 AU from the central stars. These results suggest that the binary planets can be detected by transit observations at ≳ 0.3 AU.« less

Functional phases and angular momentum characteristics of Tkatchev and Kovacs.

PubMed

Irwin, Gareth; Exell, Timothy A; Manning, Michelle L; Kerwin, David G

2017-03-01

Understanding the technical requirements and underlying biomechanics of complex release and re-grasp skills on high bar allows coaches and scientists to develop safe and effective training programmes. The aim of this study was to examine the differences in the functional phases between the Tkatchev and Kovacs skills and to explain how the angular momentum demands are addressed. Images of 18 gymnasts performing 10 Tkatchevs and 8 Kovacs at the Olympic Games were recorded (50 Hz), digitised and reconstructed (3D Direct Linear Transformation). Orientation of the functional phase action, defined by the rapid flexion to extension of the shoulders and extension to flexion of the hips as the performer passed through the lower vertical, along with shoulder and hip angular kinematics, angular momentum and key release parameters (body angle, mass centre velocity and angular momentum about the mass centre and bar) were compared between skills. Expected differences in the release parameters of angle, angular momentum and velocity were observed and the specific mechanical requirement of each skill were highlighted. Whilst there were no differences in joint kinematics, hip and shoulder functional phase were significantly earlier in the circle for the Tkatchev. These findings highlight the importance of the orientation of the functional phase in the preceding giant swing and provide coaches with further understanding of the critical timing in this key phase.

Demonstrating the Conservation of Angular Momentum Using Model Cars Moving along a Rotating Rod

ERIC Educational Resources Information Center

Abdul-Razzaq, Wathiq; Golubovic, Leonardo

2013-01-01

We have developed an exciting non-traditional experiment for our introductory physics laboratories to help students to understand the principle of conservation of angular momentum. We used electric toy cars moving along a long rotating rod. As the cars move towards the centre of the rod, the angular velocity of this system increases.…

Simplified Generation of High-Angular-Momentum Light Beams

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Maleki, Lute; Matsko, Andrey; Strekalov, Dmitry; Grudinin, Ivan

2007-01-01

A simplified method of generating a beam of light having a relatively high value of angular momentum (see figure) involves the use of a compact apparatus consisting mainly of a laser, a whispering- gallery-mode (WGM) resonator, and optical fibers. The method also can be used to generate a Bessel beam. ( Bessel beam denotes a member of a class of non-diffracting beams, so named because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have high values of angular momentum.) High-angular-momentum light beams are used in some applications in biology and nanotechnology, wherein they are known for their ability to apply torque to make microscopic objects rotate. High-angular-momentum light beams could also be used to increase bandwidths of fiber-optic communication systems. The present simplified method of generating a high-angular-momentum light beam was conceived as an alternative to prior such methods, which are complicated and require optical setups that include, variously, holograms, modulating Fabry-Perot cavities, or special microstructures. The present simplified method exploits a combination of the complex structure of the electromagnetic field inside a WGM resonator, total internal reflection in the WGM resonator, and the electromagnetic modes supported by an optical fiber. The optical fiber used to extract light from the WGM resonator is made of fused quartz. The output end of this fiber is polished flat and perpendicular to the fiber axis. The input end of this fiber is cut on a slant and placed very close to the WGM resonator at an appropriate position and orientation. To excite the resonant whispering- gallery modes, light is introduced into the WGM resonator via another optical fiber that is part of a pigtailed fiber-optic coupler. Light extracted from the WGM resonator is transformed into a high-angular- momentum beam inside the extraction optical fiber and this beam is emitted from the polished flat output end. By adjusting the geometry of this apparatus, it is possible to generate a variety of optical beams characterized by a wide range of parameters. These beams generally have high angular momenta and can be of either Bessel or Bessel-related types.

COSMIC VORTICITY AND THE ORIGIN HALO SPINS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Libeskind, Noam I.; Steinmetz, Matthias; Gottloeber, Stefan

2013-04-01

In the standard model of cosmology, structure emerges out of a non-rotational flow and the angular momentum of collapsing halos is induced by tidal torques. The growth of angular momentum in the linear and quasi-linear phases is associated with a shear, curl-free, flow and it is well described within the linear framework of tidal torque theory (TTT). However, TTT ceases to be applicable as halos approach turnaround when their ambient flow field becomes rotational. Subsequently, halos become embedded in a vortical flow field and the growth of their angular momentum is affected by the vorticity of their ambient velocity field.more » Using a cosmological simulation, we have examined the importance of the curl of the velocity field in determining halo spin, finding a significant alignment between the two: the vorticity tends to be perpendicular to the axis of the fastest collapse of the velocity shear tensor (e{sub 1}). This is independent of halo masses and cosmic web environment. Our results agree with previous findings on the tendency of halo spin to be perpendicular to e{sub 1}, and of the spin of (simulated) halos and (observed) galaxies to be aligned with the large-scale structure. It follows that angular momentum growth proceeds in two distinct phases. First, the angular momentum emerges out of a shear, curl-free, potential flow, as described by TTT. In the second phase, in which halos approach virialization, the angular momentum emerges out of a vortical flow and halo spin becomes partially aligned with the vorticity of the ambient flow field.« less

On the energy dissipation rate at the inner edge of circumbinary discs

NASA Astrophysics Data System (ADS)

Terquem, Caroline; Papaloizou, John C. B.

2017-01-01

We study, by means of numerical simulations and analysis, the details of the accretion process from a disc on to a binary system. We show that energy is dissipated at the edge of a circumbinary disc and this is associated with the tidal torque that maintains the cavity: angular momentum is transferred from the binary to the disc through the action of compressional shocks and viscous friction. These shocks can be viewed as being produced by fluid elements that drift into the cavity and, before being accreted, are accelerated on to trajectories that send them back to impact the disc. The rate of energy dissipation is approximately equal to the product of potential energy per unit mass at the disc's inner edge and the accretion rate, estimated from the disc parameters just beyond the cavity edge, that would occur without the binary. For very thin discs, the actual accretion rate on to the binary may be significantly less. We calculate the energy emitted by a circumbinary disc taking into account energy dissipation at the inner edge and also irradiation arising there from reprocessing of light from the stars. We find that, for tight PMS binaries, the SED is dominated by emission from the inner edge at wavelengths between 1-4 and 10 μm. This may apply to systems like CoRoT 223992193 and V1481 Ori.

Black Hole Accretion Discs on a Moving Mesh

NASA Astrophysics Data System (ADS)

Ryan, Geoffrey

2017-01-01

We present multi-dimensional numerical simulations of black hole accretion disks relevant for the production of electromagnetic counterparts to gravitational wave sources. We perform these simulations with a new general relativistic version of the moving-mesh magnetohydrodynamics code DISCO which we will present. This open-source code, GR-DISCO uses an orbiting and shearing mesh which moves with the dominant flow velocity, greatly improving the numerical accuracy of the thermodynamic variables in supersonic flows while also reducing numerical viscosity and greatly increasing computational efficiency by allowing for a larger time step. We have used GR-DISCO to study black hole accretion discs subject to gravitational torques from a binary companion, relevant for both current and future supermassive binary black hole searches and also as a possible electromagnetic precursor mechanism for LIGO events. Binary torques in these discs excite spiral shockwaves which effectively transport angular momentum in the disc and propagate through the innermost stable orbit, leading to stress corresponding to an alpha-viscosity of 10-2. We also present three-dimensional GRMHD simulations of neutrino dominated accretion flows (NDAFs) occurring after a binary neutron star merger in order to elucidate the conditions for electromagnetic transient production accompanying these gravitational waves sources expected to be detected by LIGO in the near future.

Swings between rotation and accretion power in a binary millisecond pulsar.

PubMed

Papitto, A; Ferrigno, C; Bozzo, E; Rea, N; Pavan, L; Burderi, L; Burgay, M; Campana, S; Di Salvo, T; Falanga, M; Filipović, M D; Freire, P C C; Hessels, J W T; Possenti, A; Ransom, S M; Riggio, A; Romano, P; Sarkissian, J M; Stairs, I H; Stella, L; Torres, D F; Wieringa, M H; Wong, G F

2013-09-26

It is thought that neutron stars in low-mass binary systems can accrete matter and angular momentum from the companion star and be spun-up to millisecond rotational periods. During the accretion stage, the system is called a low-mass X-ray binary, and bright X-ray emission is observed. When the rate of mass transfer decreases in the later evolutionary stages, these binaries host a radio millisecond pulsar whose emission is powered by the neutron star's rotating magnetic field. This evolutionary model is supported by the detection of millisecond X-ray pulsations from several accreting neutron stars and also by the evidence for a past accretion disc in a rotation-powered millisecond pulsar. It has been proposed that a rotation-powered pulsar may temporarily switch on during periods of low mass inflow in some such systems. Only indirect evidence for this transition has hitherto been observed. Here we report observations of accretion-powered, millisecond X-ray pulsations from a neutron star previously seen as a rotation-powered radio pulsar. Within a few days after a month-long X-ray outburst, radio pulses were again detected. This not only shows the evolutionary link between accretion and rotation-powered millisecond pulsars, but also that some systems can swing between the two states on very short timescales.

Measurements and calculations of high-angular-momentum satellite transitions in Li 1s photoionization

NASA Astrophysics Data System (ADS)

Cheng, W. T.; Kukk, E.; Cubaynes, D.; Chang, J.-C.; Snell, G.; Bozek, J. D.; Wuilleumier, F. J.; Berrah, N.

2000-12-01

Lithium 1s photoelectron spectra are reported in high electron and photon energy resolution, with resolved LS term structure of the Li+ 1snl satellite transitions up to n=6. Branching ratios and anisotropy parameters of individual lines, determined over the 85-130 eV photon energy range, are compared with R-matrix calculations and with previous works. The high-angular-momentum satellite lines (L>=2) are found to contribute significantly to the 1snl satellite cross sections for n=3 and 4, and to become the dominant terms for n>=5. The high-angular-momentum lines exhibit the same photon-energy-dependence as the P-lines, providing experimental evidence that the continuum-continuum state coupling (equivalent to virtual electron collision processes) is responsible for the L>=1 terms in the satellite spectrum, in contrast to the electron relaxation (shake-up) mechanism responsible for the S-terms. The angular distribution of the lines in the Li+ 1snl, n=2-6 groups, determined at 110 eV photon energy, is in good agreement with calculations, showing more isotropic distributions for high-angular-momentum lines.

Feeding supermassive black holes by collisional cascades

NASA Astrophysics Data System (ADS)

Faber, Christian; Dehnen, Walter

2018-05-01

The processes driving gas accretion on to supermassive black holes (SMBHs) are still poorly understood. Angular momentum conservation prevents gas within ˜10 pc of the black hole from reaching radii ˜10-3 pc where viscous accretion becomes efficient. Here we present simulations of the collapse of a clumpy shell of swept-up isothermal gas, which is assumed to have formed as a result of feedback from a previous episode of AGN activity. The gas falls towards the SMBH forming clumps and streams, which intersect, collide, and often form a disc. These collisions promote partial cancellations of angular momenta, resulting in further infall and more collisions. This continued collisional cascade generates a tail of gas with sufficiently small angular momenta and provides a viable route for gas inflow to sub-parsec scales. The efficiency of this process hardly depends on details, such as gas temperature, initial virial ratio and power spectrum of the gas distribution, as long as it is not strongly rotating. Adding star formation to this picture might explain the near-simultaneous formation of the S-stars (from tidally disrupted binaries formed in plunging gas streams) and the sub-parsec young stellar disc around Sgr A⋆.

Feeding supermassive black holes by collisional cascades

NASA Astrophysics Data System (ADS)

Faber, Christian; Dehnen, Walter

2018-07-01

The processes driving gas accretion on to supermassive black holes (SMBHs) are still poorly understood. Angular momentum conservation prevents gas within ˜10 pc of the black hole from reaching radii ˜10-3pc where viscous accretion becomes efficient. Here we present simulations of the collapse of a clumpy shell of swept-up isothermal gas, which is assumed to have formed as a result of feedback from a previous episode of AGN activity. The gas falls towards the SMBH forming clumps and streams, which intersect, collide and often form a disc. These collisions promote partial cancellations of angular momenta, resulting in further infall and more collisions. This continued collisional cascade generates a tail of gas with sufficiently small angular momenta and provides a viable route for gas inflow to sub-parsec scales. The efficiency of this process hardly depends on details, such as gas temperature, initial virial ratio and power spectrum of the gas distribution, as long as it is not strongly rotating. Adding star formation to this picture might explain the near-simultaneous formation of the S-stars (from tidally disrupted binaries formed in plunging gas streams) and the sub-parsec young stellar disc around Sgr A⋆.

Emergence of transverse spin in optical modes of semiconductor nanowires

DOE PAGES

Alizadeh, M. H.; Reinhard, Bjorn M.

2016-04-11

The transverse spin angular momentum of light has recently received tremendous attention as it adds a new degree of freedom for controlling light-matter interactions. In this work we demonstrate the generation of transverse spin angular momentum by the weakly-guided mode of semiconductor nanowires. The evanescent field of these modes in combination with the transversality condition rigorously accounts for the occurrence of transverse spin angular momentum. Furthermore, the intriguing and nontrivial spin properties of optical modes in semiconductor nanowires are of high interest for a broad range of new applications including chiral optical trapping, quantum information processing, and nanophotonic circuitry.

High Angular Momentum Halo Gas: A Feedback and Code-independent Prediction of LCDM

NASA Astrophysics Data System (ADS)

Stewart, Kyle R.; Maller, Ariyeh H.; Oñorbe, Jose; Bullock, James S.; Joung, M. Ryan; Devriendt, Julien; Ceverino, Daniel; Kereš, Dušan; Hopkins, Philip F.; Faucher-Giguère, Claude-André

2017-07-01

We investigate angular momentum acquisition in Milky Way-sized galaxies by comparing five high resolution zoom-in simulations, each implementing identical cosmological initial conditions but utilizing different hydrodynamic codes: Enzo, Art, Ramses, Arepo, and Gizmo-PSPH. Each code implements a distinct set of feedback and star formation prescriptions. We find that while many galaxy and halo properties vary between the different codes (and feedback prescriptions), there is qualitative agreement on the process of angular momentum acquisition in the galaxy’s halo. In all simulations, cold filamentary gas accretion to the halo results in ˜4 times more specific angular momentum in cold halo gas (λ cold ≳ 0.1) than in the dark matter halo. At z > 1, this inflow takes the form of inspiraling cold streams that are co-directional in the halo of the galaxy and are fueled, aligned, and kinematically connected to filamentary gas infall along the cosmic web. Due to the qualitative agreement among disparate simulations, we conclude that the buildup of high angular momentum halo gas and the presence of these inspiraling cold streams are robust predictions of Lambda Cold Dark Matter galaxy formation, though the detailed morphology of these streams is significantly less certain. A growing body of observational evidence suggests that this process is borne out in the real universe.

The Formation and Fragmentation of Primordial Protostellar Discs

NASA Astrophysics Data System (ADS)

Clark, Paul C.; Glover, Simon C. O.; Smith, Rowan J.; Greif, Thomas H.; Klessen, Ralf S.; Bromm, Volker

2010-11-01

We study the formation and evolution of the protostellar discs that form around the first stars in the Universe. Using sink particles, we replace the gravitationally bound gas at densities higher than 1015 cm-3 and radii greater than 3 AU from the central protostellar core, with an accreting point mass that is able to gravitationally interact with the surrounding gas. We find the disc is gravitationally (or `Toomre') unstable, and is dominated by a strong m = 2 spiral mode. Although the angular momentum transport is dominated by a combination of gravitational torques and Reynolds stresses, which are extremely efficient mechanisms, the disc is unable to process the infalling material and grows increasingly gravitationally unstable. During the build-up of the disc, the temperature in the gas is regulated by a combination of H2 line cooling, collision-induced emission and H2 dissociation, which together help to offset heating from the gravitational collapse and feedback from the protostar. Once the disc starts to fragment, H2 dissociation keeps the gas almost isothermal as the collapse of the fragment progresses. The fragmentation occurs when the protostar/disc system is only 230 yr old and at a distance of ~20 AU from its sibling, by which point the central protostar has a mass of ~1 Msolar. Given the angular momentum of the new protostellar system, it is likely that the protostars will grow to become a massive binary system.

A primordial origin for misalignments between stellar spin axes and planetary orbits.

PubMed

Batygin, Konstantin

2012-11-15

The existence of gaseous giant planets whose orbits lie close to their host stars ('hot Jupiters') can largely be accounted for by planetary migration associated with viscous evolution of proto-planetary nebulae. Recently, observations of the Rossiter-McLaughlin effect during planetary transits have revealed that a considerable fraction of hot Jupiters are on orbits that are misaligned with respect to the spin axes of their host stars. This observation has cast doubt on the importance of disk-driven migration as a mechanism for producing hot Jupiters. Here I show that misaligned orbits can be a natural consequence of disk migration in binary systems whose orbital plane is uncorrelated with the spin axes of the individual stars. The gravitational torques arising from the dynamical evolution of idealized proto-planetary disks under perturbations from massive distant bodies act to misalign the orbital planes of the disks relative to the spin poles of their host stars. As a result, I suggest that in the absence of strong coupling between the angular momentum of the disk and that of the host star, or of sufficient dissipation that acts to realign the stellar spin axis and the planetary orbits, the fraction of planetary systems (including systems of 'hot Neptunes' and 'super-Earths') whose angular momentum vectors are misaligned with respect to their host stars will be commensurate with the rate of primordial stellar multiplicity.

High-mass X-ray binary populations. 1: Galactic modeling

NASA Technical Reports Server (NTRS)

Dalton, William W.; Sarazin, Craig L.

1995-01-01

Modern stellar evolutionary tracks are used to calculate the evolution of a very large number of massive binary star systems (M(sub tot) greater than or = 15 solar mass) which cover a wide range of total masses, mass ratios, and starting separations. Each binary is evolved accounting for mass and angular momentum loss through the supernova of the primary to the X-ray binary phase. Using the observed rate of star formation in our Galaxy and the properties of massive binaries, we calculate the expected high-mass X-ray binary (HMXRB) population in the Galaxy. We test various massive binary evolutionary scenarios by comparing the resulting HMXRB predictions with the X-ray observations. A major goal of this study is the determination of the fraction of matter lost from the system during the Roche lobe overflow phase. Curiously, we find that the total numbers of observable HMXRBs are nearly independent of this assumed mass-loss fraction, with any of the values tested here giving acceptable agreement between predicted and observed numbers. However, comparison of the period distribution of our HMXRB models with the observed period distribution does reveal a distinction among the various models. As a result of this comparison, we conclude that approximately 70% of the overflow matter is lost from a massive binary system during mass transfer in the Roche lobe overflow phase. We compare models constructed assuming that all X-ray emission is due to accretion onto the compact object from the donor star's wind with models that incorporate a simplified disk accretion scheme. By comparing the results of these models with observations, we conclude that the formation of disks in HMXRBs must be relatively common. We also calculate the rate of formation of double degenerate binaries, high velocity detached compact objects, and Thorne-Zytkow objects.

Cool stars, stellar systems, and the sun; Proceedings of the 7th Cambridge Workshop, Tucson, AZ, Oct. 9-12, 1991

NASA Technical Reports Server (NTRS)

Giampapa, Mark S. (Editor); Bookbinder, Jay A. (Editor)

1992-01-01

Consideration is given to HST observations of late-type stars, molecular absorption in the UV spectrum of Alpha Ori, EUV emission from late-type stars, Rosat observations of the Pleiades cluster, a deep ROSAT observation of the Hyades cluster, optical spectroscopy detected by EXOSAT, stellar photospheric convection, a structure of the solar X-ray corona, magnetic surface images of the BY Dra Star HD 82558, a Zebra interpretatin of BY Dra stars, optical flares on II Peg, a low-resolution spectroscopic survey of post-T tauri candidates, millimeter and sub-millimeter emission from flare stars, and activity in tidally interacting binaries. Attention is also given to modeling stellar angular momentum evolution, extended 60-micron emission from nearby Mira variables, the PANDORA atmosphere program, the global properties of active regions, oscillations in a stratified atmosphere, lithium abundances in northern RS CVn binaries, a new catalog of cool dwarf stars, the Far UV Spectrograph Explorer, and development of reflecting coronagraphs.

Dynamics of oscillating relativistic tori around Kerr black holes

NASA Astrophysics Data System (ADS)

Zanotti, Olindo; Font, José A.; Rezzolla, Luciano; Montero, Pedro J.

2005-02-01

We present a comprehensive numerical study of the dynamics of relativistic axisymmetric accretion tori with a power-law distribution of specific angular momentum orbiting in the background space-time of a Kerr black hole. By combining general relativistic hydrodynamics simulations with a linear perturbative approach we investigate the main dynamical properties of these objects over a large parameter space. The astrophysical implications of our results extend and improve two interesting results that have been recently reported in the literature. First, the induced quasi-periodic variation of the mass quadrupole moment makes relativistic tori of nuclear matter densities, as those formed during the last stages of binary neutron star mergers, promising sources of gravitational radiation, potentially detectable by interferometric instruments. Secondly, p-mode oscillations in relativistic tori of low rest-mass densities could be used to explain high-frequency quasi-periodic oscillations observed in X-ray binaries containing a black hole candidate under conditions more generic than those considered so far.

The HD molecule in small and medium cages of clathrate hydrates: Quantum dynamics studied by neutron scattering measurements and computation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colognesi, Daniele; Celli, Milva; Ulivi, Lorenzo, E-mail: lorenzo.ulivi@isc.cnr.it

2014-10-07

We report inelastic neutron scattering (INS) measurements on molecular hydrogen deuteride (HD) trapped in binary cubic (sII) and hexagonal (sH) clathrate hydrates, performed at low temperature using two different neutron spectrometers in order to probe both energy and momentum transfer. The INS spectra of binary clathrate samples exhibit a rich structure containing sharp bands arising from both the rotational transitions and the rattling modes of the guest molecule. For the clathrates with sII structure, there is a very good agreement with the rigorous fully quantum simulations which account for the subtle effects of the anisotropy, angular and radial, of themore » host cage on the HD microscopic dynamics. The sH clathrate sample presents a much greater challenge, due to the uncertainties regarding the crystal structure, which is known only for similar crystals with different promoter, but nor for HD (or H{sub 2}) plus methyl tert-butyl ether (MTBE-d12)« less

RUNAWAY DWARF CARBON STARS AS CANDIDATE SUPERNOVA EJECTA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plant, Kathryn A.; Margon, Bruce; Guhathakurta, Puragra

2016-12-20

The dwarf carbon (dC) star SDSS J112801.67+004034.6 has an unusually high radial velocity, 531 ± 4 km s{sup −1}. We present proper motion and new spectroscopic observations which imply a large Galactic rest frame velocity, 425 ± 9 km s{sup −1}. Several other SDSS dC stars are also inferred to have very high galactocentric velocities, again each based on both high heliocentric radial velocity and also confidently detected proper motions. Extreme velocities and the presence of C {sub 2} bands in the spectra of dwarf stars are both rare. Passage near the Galactic center can accelerate stars to such extreme velocities, but the largemore » orbital angular momentum of SDSS J1128 precludes this explanation. Ejection from a supernova in a binary system or disruption of a binary by other stars are possibilities, particularly as dC stars are thought to obtain their photospheric C {sub 2} via mass transfer from an evolved companion.« less

A Neutron Star-White Dwarf Binary Model for Repeating Fast Radio Burst 121102

NASA Astrophysics Data System (ADS)

Gu, Wei-Min; Dong, Yi-Ze; Liu, Tong; Ma, Renyi; Wang, Junfeng

2016-06-01

We propose a compact binary model for the fast radio burst (FRB) repeaters, where the system consists of a magnetic white dwarf (WD) and a neutron star (NS) with strong bipolar magnetic fields. When the WD fills its Roche lobe, mass transfer will occur from the WD to the NS through the inner Lagrange point. The accreted magnetized materials may trigger magnetic reconnection when they approach the NS surface, and therefore the electrons can be accelerated to an ultra-relativistic speed. In this scenario, the curvature radiation of the electrons moving along the NS magnetic field lines can account for the characteristic frequency and the timescale of an FRB. Owing to the conservation of angular momentum, the WD may be kicked away after a burst, and the next burst may appear when the system becomes semi-detached again through the gravitational radiation. By comparing our analyses with the observations, we show that such an intermittent Roche-lobe overflow mechanism can be responsible for the observed repeating behavior of FRB 121102.

Quasi-spherical accretion in High Mass X-ray Binaries

NASA Astrophysics Data System (ADS)

Postnov, Konstantin

2016-07-01

Quasi-spherical accreion onto magnetized neutron stars from stellar winds in high-mass X-ray binaries is discussed. Depending on the X-ray luminosity of the neutron star, the accretion can proceed in two regimes (modes): at L_x ≳ 4× 10^{36} erg/s, Compton cooling of accreting matter near magnetosphere leads to a supersonic (Bondi) accretion, while at smaller X-ray luminosity the Compton cooling is ineffective, and subsonic settling accretion regime sets in. In this regime, a hot convective shell is formed around the magnetosphere, and the plasma entry rate into magnetosphere is controlled by less effective radiative plasma cooling. The shell mediates the angular momentum transfer from/to the neutron star magnetosphere. Observational evidences for the different accretion regimes in slowly rotating X-ray pulsars with moderate and low X-ray luminosity, as well as possible manifestations of non-stationary quasi-spherical settling accretion due to the magnetospheric shell instability in Supergiant Fast X-ray Transients will be presented.

Separation of spin and orbital angular coherence momenta in the second-order coherence theory of vector electromagnetic fields.

PubMed

Wang, Wei; Takeda, Mitsuo

2007-09-15

In analogy with the separation of the total optical angular momentum into a spin and an orbital part in electrodynamics, we introduce a new concept of spin and orbital angular coherence momenta into the general coherence theory of vector electromagnetic fields. The properties of the newly introduced spin and orbital angular coherence momenta are investigated through the decomposition of the total coherence angular momentum into the sum of these two components, and their separate conservations have been derived for what is believed to be the first time.

Hanbury Brown and Twiss interferometry with twisted light

PubMed Central

Magaña-Loaiza, Omar S.; Mirhosseini, Mohammad; Cross, Robert M.; Rafsanjani, Seyed Mohammad Hashemi; Boyd, Robert W.

2016-01-01

The rich physics exhibited by random optical wave fields permitted Hanbury Brown and Twiss to unveil fundamental aspects of light. Furthermore, it has been recognized that optical vortices are ubiquitous in random light and that the phase distribution around these optical singularities imprints a spectrum of orbital angular momentum onto a light field. We demonstrate that random fluctuations of intensity give rise to the formation of correlations in the orbital angular momentum components and angular positions of pseudothermal light. The presence of these correlations is manifested through distinct interference structures in the orbital angular momentum–mode distribution of random light. These novel forms of interference correspond to the azimuthal analog of the Hanbury Brown and Twiss effect. This family of effects can be of fundamental importance in applications where entanglement is not required and where correlations in angular position and orbital angular momentum suffice. We also suggest that the azimuthal Hanbury Brown and Twiss effect can be useful in the exploration of novel phenomena in other branches of physics and astrophysics. PMID:27152334

Rigidly rotating zero-angular-momentum observer surfaces in the Kerr spacetime

NASA Astrophysics Data System (ADS)

Frolov, Andrei V.; Frolov, Valeri P.

2014-12-01

A stationary observer in the Kerr spacetime has zero angular momentum if their angular velocity ω has a particular value, which depends on the position of the observer. Worldlines of such zero-angular-momentum observers (ZAMOs) with the same value of the angular velocity ω form a three-dimensional surface, which has the property that the Killing vectors generating time translation and rotation are tangent to it. We call such a surface a rigidly rotating ZAMO surface. This definition allows for a natural generalization to the surfaces inside the black hole, where ZAMO trajectories formally become spacelike. A general property of such a surface is that there exist linear combinations of the Killing vectors with constant coefficients which make them orthogonal on it. In this paper we discuss properties of the rigidly rotating ZAMO surfaces both outside and inside the black hole and the relevance of these objects to a couple of interesting physical problems.

Induced Angular Momentum

ERIC Educational Resources Information Center

Parker, G. W.

1978-01-01

Discusses, classically and quantum mechanically, the angular momentum induced in the bound motion of an electron by an external magnetic field. Calculates the current density and its magnetic moment, and then uses two methods to solve the first-order perturbation theory equation for the required eigenfunction. (Author/GA)

Hydrodynamical simulations of the tidal stripping of binary stars by massive black holes

NASA Astrophysics Data System (ADS)

Mainetti, Deborah; Lupi, Alessandro; Campana, Sergio; Colpi, Monica

2016-04-01

In a galactic nucleus, a star on a low angular momentum orbit around the central massive black hole can be fully or partially disrupted by the black hole tidal field, lighting up the compact object via gas accretion. This phenomenon can repeat if the star, not fully disrupted, is on a closed orbit. Because of the multiplicity of stars in binary systems, also binary stars may experience in pairs such a fate, immediately after being tidally separated. The consumption of both the binary components by the black hole is expected to power a double-peaked flare. In this paper, we perform for the first time, with GADGET2, a suite of smoothed particle hydrodynamics simulations of binary stars around a galactic central black hole in the Newtonian regime. We show that accretion luminosity light curves from double tidal disruptions reveal a more prominent knee, rather than a double peak, when decreasing the impact parameter of the encounter and when elevating the difference between the mass of the star which leaves the system after binary separation and the mass of the companion. The detection of a knee can anticipate the onset of periodic accretion luminosity flares if one of the stars, only partially disrupted, remains bound to the black hole after binary separation. Thus knees could be precursors of periodic flares, which can then be predicted, followed up and better modelled. Analytical estimates in the black hole mass range 105-108 M⊙ show that the knee signature is enhanced in the case of black holes of mass 106-107 M⊙.

The angular momentum of disc galaxies: implications for gas accretion, outflows, and dynamical friction

NASA Astrophysics Data System (ADS)

Dutton, Aaron A.; van den Bosch, Frank C.

2012-03-01

We combine constraints on the galaxy-dark matter connection with structural and dynamical scaling relations to investigate the angular momentum content of disc galaxies. For haloes with masses in the interval 1011.3 M⊙≲Mvir≲ 1012.7 M⊙ we find that the galaxy spin parameters are basically independent of halo mass with ?. This is significantly lower than for relaxed Λcold dark matter (ΛCDM) haloes, which have an average spin parameter ?. The average ratio between the specific angular momentum of disc galaxies and their host dark matter haloes is therefore ?. This calls into question a standard assumption made in the majority of all (semi-analytical) models for (disc) galaxy formation, namely that ?. Using simple disc formation models we show that it is particularly challenging to understand why ? is independent of halo mass, while the galaxy formation efficiency (ɛGF; proportional to the ratio of galaxy mass to halo mass) reveals a strong halo mass dependence. We argue that the empirical scaling relations between ɛGF, ? and halo mass require both feedback (i.e. galactic outflows) and angular momentum transfer from the baryons to the dark matter (i.e. dynamical friction). Most importantly, the efficiency of angular momentum loss needs to decrease with increasing halo mass. Such a mass dependence may reflect a bias against forming stable discs in high-mass, low-spin haloes or a transition from cold-mode accretion in low-mass haloes to hot-mode accretion at the massive end. However, current hydrodynamical simulations of galaxy formation, which should include these processes, seem unable to reproduce the empirical relation between ɛGF and ?. We conclude that the angular momentum build-up of galactic discs remains poorly understood.

Overlapping inflow events as catalysts for supermassive black hole growth

NASA Astrophysics Data System (ADS)

Carmona-Loaiza, Juan M.; Colpi, Monica; Dotti, Massimo; Valdarnini, Riccardo

2014-02-01

One of the greatest issues in modelling black hole fuelling is our lack of understanding of the processes by which gas loses angular momentum and falls from galactic scales down to the nuclear region where an accretion disc forms, subsequently guiding the inflow of gas down to the black hole horizon. It is feared that gas at larger scales might still retain enough angular momentum and settle into a larger scale disc with very low or no inflow to form or replenish the inner accretion disc (on ˜0.01 pc scales). In this paper we report on hydrodynamical simulations of rotating infalling gas shells impacting at different angles on to a pre-existing, primitive large-scale (˜10 pc) disc around a supermassive black hole. The aim is to explore how the interaction between the shell and the disc redistributes the angular momentum on scales close to the black hole's sphere of influence. Angular momentum redistribution via hydrodynamical shocks leads to inflows of gas across the inner boundary, enhancing the inflow rate by more than 2-3 orders of magnitude. In all cases, the gas inflow rate across the inner parsec is higher than in the absence of the interaction, and the orientation of the angular momentum of the flow in the region changes with time due to gas mixing. Warped discs or nested misaligned rings form depending on the angular momentum content of the infalling shell relative to the disc. In the cases in which the shell falls in near counter-rotation, part of the resulting flows settle into an inner dense disc which becomes more susceptible to mass transfer.

Effective-one-body model for black-hole binaries with generic mass ratios and spins

NASA Astrophysics Data System (ADS)

Taracchini, Andrea; Buonanno, Alessandra; Pan, Yi; Hinderer, Tanja; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Lovelace, Geoffrey; Mroué, Abdul H.; Pfeiffer, Harald P.; Scheel, Mark A.; Szilágyi, Béla; Taylor, Nicholas W.; Zenginoglu, Anil

2014-03-01

Gravitational waves emitted by black-hole binary systems have the highest signal-to-noise ratio in LIGO and Virgo detectors when black-hole spins are aligned with the orbital angular momentum and extremal. For such systems, we extend the effective-one-body inspiral-merger-ringdown waveforms to generic mass ratios and spins calibrating them to 38 numerical-relativity nonprecessing waveforms produced by the SXS Collaboration. The numerical-relativity simulations span mass ratios from 1 to 8, spin magnitudes up to 98% of extremality, and last for 40 to 60 gravitational-wave cycles. When the total mass of the binary is between 20 and 200M⊙, the effective-one-body nonprecessing (dominant mode) waveforms have overlap above 99% (using the advanced-LIGO design noise spectral density) with all of the 38 nonprecessing numerical waveforms, when maximizing only on initial phase and time. This implies a negligible loss in event rate due to modeling. We also show that—without further calibration— the precessing effective-one-body (dominant mode) waveforms have overlap above 97% with two very long, strongly precessing numerical-relativity waveforms, when maximizing only on the initial phase and time.

3D Modeling of Forbidden Line Emission in the Binary Wind Interaction Region of Eta Carinae

NASA Technical Reports Server (NTRS)

Madura, Thomas; Gull, T. R.; Owocki, S.; Okazaki, A. T.; Russell, C. M. P.

2010-01-01

We present recent work using three-dimensional (3D) Smoothed Particle Hydrodynamics (SPH) simulations to model the high ([Fe III], [Ar III], [Ne III] and [S III]) and low ([Fe II], [Ni II]) ionization forbidden emission lines observed in Eta Carinae using the HST/STIS. These structures are interpreted as the time-averaged, outer extensions of the primary wind and the wind-wind interaction region directly excited by the FUV of the hot companion star of this massive binary system. We discuss how analyzing the results of the 3D SPH simulations and synthetic slit spectra and comparing them to the spectra obtained with the HST/STIS helps us determine the absolute orientation of the binary orbit and helps remove the degeneracy inherent to models based solely on the observed RXTE X-ray light curve. A key point of this work is that spatially resolved observations like those with HST/STIS and comparison to 3D models are necessary to determine the alignment or misalignment of the orbital angular momentum axis with the Homunculus, or correspondingly, the alignment of the orbital plane with the Homunculus skirt.

Orbital period variability in the eclipsing pulsar binary PSR B1957+20: Evidence for a tidally powered star

NASA Technical Reports Server (NTRS)

Applegate, James H.; Shaham, Jacob

1994-01-01

Recent observations indicate that the eclipsing pulsar binary PSR B1957+20 undergoes alternating epochs of orbital period increase and decrease. We apply a model developed to explain orbital period changes of alternating sign in other binaries to the PSR B1957+20 system and find that it fits the pulsars observations well. The novel feature of the PSR B1957+20 system is that the energy flow in the companion needed to power the orbital period change mechanism can be supplied by tidal dissipation, making the companion the first identified tidally powered star. The flow of energy in the companion drives magnetic activity, which underlies the observed orbital period variations. The magnetic activity and the wind driven by the pulsar irradiation results in a torque on the spin of the companion. This torque holds the companion out of synchronous rotation, causing tidal dissipation of energy. We propose that the progenitor had a approximately 2 hr orbital period and a companion mass of 0.1-0.2 solar mass, and the system is evolving to longer orbital periods by mass and angular momentum loss on a timescale of 10(exp 8) yr.

The BANANA project. V. Misaligned and precessing stellar rotation axes in CV Velorum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albrecht, Simon; Winn, Joshua N.; Triaud, Amaury

As part of the Binaries Are Not Always Neatly Aligned project (BANANA), we have found that the eclipsing binary CV Velorum has misaligned rotation axes. Based on our analysis of the Rossiter-McLaughlin effect, we find sky-projected spin-orbit angles of β{sub p} = –52° ± 6° and β{sub s} = 3° ± 7° for the primary and secondary stars (B2.5V + B2.5V, P = 6.9 days). We combine this information with several measurements of changing projected stellar rotation speeds (vsin i {sub *}) over the last 30 yr, leading to a model in which the primary star's obliquity is ≈65°, andmore » its spin axis precesses around the total angular momentum vector with a period of about 140 yr. The geometry of the secondary star is less clear, although a significant obliquity is also implicated by the observed time variations in the vsin i {sub *}. By integrating the secular tidal evolution equations backward in time, we find that the system could have evolved from a state of even stronger misalignment similar to DI Herculis, a younger but otherwise comparable binary.« less

Be/X-Ray Pulsar Binary Science with LOFT

NASA Technical Reports Server (NTRS)

Wilson-Hodge, Colleen A.

2011-01-01

Accretion disks are ubiquitous in astronomical sources. Accretion powered pulsars are a good test bed for accretion disk physics, because unlike for other objects, the spin of the neutron star is directly observable allowing us to see the effects of angular momentum transfer onto the pulsar. The combination of a sensitive wide-field monitor and the large area detector on LOFT will enable new detailed studies of accretion powered pulsars which I will review. RXTE observations have shown an unusually high number of Be/X-ray pulsar binaries in the SMC. Unlike binaries in the Milky Way, these systems are all at the same distance, allowing detailed population studies using the sensitive LOFT WFM, potentially providing connections to star formation episodes. For Galactic accreting pulsar systems, LOFT will allow measurement of spectral variations within individual pulses, mapping the accretion column in detail for the first time. LOFT will also provide better constraints on magnetic fields in accreting pulsars, allowing measurements of cyclotron features, observations of transitions into the centrifugal inhibition regime, and monitoring of spin-up rate vs flux correlations. Coordinated multi-wavelength observations are crucial to extracting the best science from LOFT from these and numerous other objects.

The Formation of Rapidly Rotating Black Holes in High-mass X-Ray Binaries

NASA Astrophysics Data System (ADS)

Batta, Aldo; Ramirez-Ruiz, Enrico; Fryer, Chris

2017-09-01

High-mass X-ray binaries (HMXRBs), such as Cygnus X-1, host some of the most rapidly spinning black holes (BHs) known to date, reaching spin parameters a≳ 0.84. However, there are several effects that can severely limit the maximum BH spin parameter that could be obtained from direct collapse, such as tidal synchronization, magnetic core-envelope coupling, and mass loss. Here, we propose an alternative scenario where the BH is produced by a failed supernova (SN) explosion that is unable to unbind the stellar progenitor. A large amount of fallback material ensues, whose interaction with the secondary naturally increases its overall angular momentum content, and therefore the spin of the BH when accreted. Through SPH hydrodynamic simulations, we studied the unsuccessful explosion of an 8 {M}⊙ pre-SN star in a close binary with a 12 {M}⊙ companion with an orbital period of ≈1.2 days, finding that it is possible to obtain a BH with a high spin parameter a≳ 0.8 even when the expected spin parameter from direct collapse is a≲ 0.3. This scenario also naturally explains the atmospheric metal pollution observed in HMXRB stellar companions.

A homogeneous sample of binary galaxies: Basic observational properties

NASA Technical Reports Server (NTRS)

Karachentsev, I. D.

1990-01-01

A survey of optical characteristics for 585 binary systems, satisfying a condition of apparent isolation on the sky, is presented. Influences of various selection effects distorting the average parameters of the sample are noted. The pair components display mutual similarity over all the global properties: luminosity, diameter, morphological type, mass-to-luminosity ratio, angular momentum etc., which is not due only to selection effects. The observed correlations must be caused by common origin of pair members. Some features (nuclear activity, color index) could acquire similarity during synchronous evolution of double galaxies. Despite the observed isolation, the sample of double systems is seriously contaminated by accidental pairs, and also by members of groups and clusters. After removing false pairs estimates of orbital mass-to-luminosity ratio range from 0 to 30 f(solar), with the mean value (7.8 plus or minus 0.7) f(solar). Binary galaxies possess nearly circular orbits with a typical eccentrity e = 0.25, probably resulting from evolutionary selection driven by component mergers under dynamical friction. The double-galaxy population with space abundance 0.12 plus or minus 0.02 and characteristic merger timescale 0.2 H(exp -1) may significantly influence the rate of dynamical evolution of galaxies.

Mid-IR Lasers: Challenges Imposed by the Population Dynamics of the Gain System

DTIC Science & Technology

2010-09-01

MicroSystems (IOMS) Central-Field Approximation: Perturbations 1. a) Non-centrosymmetric splitting (Coulomb interaction) ⇒ total orbital angular momentum b...Accordingly: ⇒ total electron-spin momentum 2. Spin-orbit coupling (“LS” coupling) ⇒ total angular momentum lanthanides: intermediate coupling (LS / jj) 3...MicroSystems (IOMS) Luminescence Decay Curves Rate-equation for decay: Solution ( Bernoulli -Eq.): Linearized solution: T. Jensen, Ph.D. Thesis, Univ. Hamburg

Analytical scheme calculations of angular momentum coupling and recoupling coefficients

NASA Astrophysics Data System (ADS)

Deveikis, A.; Kuznecovas, A.

2007-03-01

We investigate the Scheme programming language opportunities to analytically calculate the Clebsch-Gordan coefficients, Wigner 6j and 9j symbols, and general recoupling coefficients that are used in the quantum theory of angular momentum. The considered coefficients are calculated by a direct evaluation of the sum formulas. The calculation results for large values of quantum angular momenta were compared with analogous calculations with FORTRAN and Java programming languages.

Rotating Wavepackets

ERIC Educational Resources Information Center

Lekner, John

2008-01-01

Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…

The rigid shell component for superrotation in planetary atmospheres: Angular momentum budget, mechanical analog and simulation of the spin up process

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Harris, I.

1981-01-01

An analysis of superrotation in the atmosphere of planets, with rotation axis perpendicular to the orbital plane is presented. As the atmosphere expands, Hadley cells develop producing a redistribution of mass and angular momentum. A three dimensional thermally driven zonally symmetric spectral model and Laplace transformation simulate the time evolution of a fluid leading from corotation under globally uniform heating to superrotation under globally nonuniform heating. For high viscosities the rigid shell component of atmospheric superrotation can be understood in analogy with a pirouette. During spin up angular momentum is transferred to the planet. For low iscosities, the process is reversed. A tendency toward geostrophy, combined with increase of surface pressure toward the poles (due to meridional mass transport), induces the atmosphere to subrotate temporarily at lower altitudes. Resultant viscous shear near the surface permits angular momentum to flow from the planet into the atmosphere propagating upwards to produce high altitude superrotation rates.

Tunable orbital angular momentum in high-harmonic generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gauthier, David; Ribič, P. Rebernik; Adhikary, G.

Optical vortices are currently one of the most intensively studied topics in optics. These light beams, which carry orbital angular momentum (OAM), have been successfully utilized in the visible and infrared in a wide variety of applications. Moving to shorter wavelengths may open up completely new research directions in the areas of optical physics and material characterization. Here, we report on the generation of extreme-ultraviolet optical vortices with femtosecond duration carrying a controllable amount of OAM. From a basic physics viewpoint, our results help to resolve key questions such as the conservation of angular momentum in highly nonlinear light–matter interactions,more » and the disentanglement and independent control of the intrinsic and extrinsic components of the photon’s angular momentum at short-wavelengths. Finally, the methods developed here will allow testing some of the recently proposed concepts such as OAM-induced dichroism, magnetic switching in organic molecules and violation of dipolar selection rules in atoms.« less

Orbital and spin angular momentum in conical diffraction

NASA Astrophysics Data System (ADS)

Berry, M. V.; Jeffrey, M. R.; Mansuripur, M.

2005-11-01

The angular momentum Jinc of a light beam can be changed by passage through a slab of crystal. When the beam is incident along the optic axis of a biaxial crystal, which may also possess optical activity (chirality), the final angular momentum J can have both orbital (Jorb) and spin (Jsp) contributions, which we calculate paraxially exactly for arbitrary biaxiality and chirality and initially uniformly polarized beams with circular symmetry. For the familiar special case of a non-chiral crystal with fully developed conical-refraction rings, J is purely orbital and equal to Jinc/2, reflecting an interesting singularity structure in the beam. Explicit formulas and numerical computations are presented for a Gaussian incident beam. The change in angular momentum results in a torque on the crystal, along the axis of the incident beam. An additional, much larger, torque, about an axis lying in the slab, arises from the offset of the cone of conical refraction relative to the incident beam.

Catalystlike effect of orbital angular momentum on the conversion of transverse to three-dimensional spin states within tightly focused radially polarized beams

NASA Astrophysics Data System (ADS)

Han, Lei; Liu, Sheng; Li, Peng; Zhang, Yi; Cheng, Huachao; Zhao, Jianlin

2018-05-01

We report on the catalystlike effect of orbital angular momentum (OAM) on local spin-state conversion within the tightly focused radially polarized beams associated with optical spin-orbit interaction. It is theoretically demonstrated that the incident OAM can lead to a conversion of purely transverse spin state to a three-dimensional spin state on the focal plane. This conversion can be conveniently manipulated by altering the sign and value of the OAM. By comparing the total OAM and spin angular momentum (SAM) on the incident plane to those on the focal plane, it is indicated that the incident OAM have no participation in the angular momentum intertransfer, and just play a role as a catalyst of local SAM conversion. Such an effect of OAM sheds new light on the optical spin-orbit interaction in tight-focusing processes. The resultant three-dimensional spin states may provide more degrees of freedom in optical manipulation and spin-dependent directive coupling.

Shocks in the relativistic transonic accretion with low angular momentum

NASA Astrophysics Data System (ADS)

Suková, P.; Charzyński, S.; Janiuk, A.

2017-12-01

We perform 1D/2D/3D relativistic hydrodynamical simulations of accretion flows with low angular momentum, filling the gap between spherically symmetric Bondi accretion and disc-like accretion flows. Scenarios with different directional distributions of angular momentum of falling matter and varying values of key parameters such as spin of central black hole, energy and angular momentum of matter are considered. In some of the scenarios the shock front is formed. We identify ranges of parameters for which the shock after formation moves towards or outwards the central black hole or the long-lasting oscillating shock is observed. The frequencies of oscillations of shock positions which can cause flaring in mass accretion rate are extracted. The results are scalable with mass of central black hole and can be compared to the quasi-periodic oscillations of selected microquasars (such as GRS 1915+105, XTE J1550-564 or IGR J17091-3624), as well as to the supermassive black holes in the centres of weakly active galaxies, such as Sgr A*.

Tunable orbital angular momentum in high-harmonic generation

DOE PAGES

Gauthier, David; Ribič, P. Rebernik; Adhikary, G.; ...

2017-04-05

Optical vortices are currently one of the most intensively studied topics in optics. These light beams, which carry orbital angular momentum (OAM), have been successfully utilized in the visible and infrared in a wide variety of applications. Moving to shorter wavelengths may open up completely new research directions in the areas of optical physics and material characterization. Here, we report on the generation of extreme-ultraviolet optical vortices with femtosecond duration carrying a controllable amount of OAM. From a basic physics viewpoint, our results help to resolve key questions such as the conservation of angular momentum in highly nonlinear light–matter interactions,more » and the disentanglement and independent control of the intrinsic and extrinsic components of the photon’s angular momentum at short-wavelengths. Finally, the methods developed here will allow testing some of the recently proposed concepts such as OAM-induced dichroism, magnetic switching in organic molecules and violation of dipolar selection rules in atoms.« less

Lunar-forming impacts: processes and alternatives

PubMed Central

Canup, R. M.

2014-01-01

The formation of a protolunar disc by a giant impact with the early Earth is discussed, focusing on two classes of impacts: (i) canonical impacts, in which a Mars-sized impactor produces a planet–disc system whose angular momentum is comparable to that in the current Earth and Moon, and (ii) high-angular-momentum impacts, which produce a system whose angular momentum is approximately a factor of 2 larger than that in the current Earth and Moon. In (i), the disc originates primarily from impactor-derived material and thus is expected to have an initial composition distinct from that of the Earth's mantle. In (ii), a hotter, more compact initial disc is produced with a silicate composition that can be nearly identical to that of the silicate Earth. Both scenarios require subsequent processes for consistency with the current Earth and Moon: disc–planet compositional equilibration in the case of (i), or large-scale angular momentum loss during capture of the newly formed Moon into the evection resonance with the Sun in the case of (ii). PMID:25114302

Controlled enhancement of spin-current emission by three-magnon splitting.

PubMed

Kurebayashi, Hidekazu; Dzyapko, Oleksandr; Demidov, Vladislav E; Fang, Dong; Ferguson, A J; Demokritov, Sergej O

2011-07-03

Spin currents--the flow of angular momentum without the simultaneous transfer of electrical charge--play an enabling role in the field of spintronics. Unlike the charge current, the spin current is not a conservative quantity within the conduction carrier system. This is due to the presence of the spin-orbit interaction that couples the spin of the carriers to angular momentum in the lattice. This spin-lattice coupling acts also as the source of damping in magnetic materials, where the precessing magnetic moment experiences a torque towards its equilibrium orientation; the excess angular momentum in the magnetic subsystem flows into the lattice. Here we show that this flow can be reversed by the three-magnon splitting process and experimentally achieve the enhancement of the spin current emitted by the interacting spin waves. This mechanism triggers angular momentum transfer from the lattice to the magnetic subsystem and modifies the spin-current emission. The finding illustrates the importance of magnon-magnon interactions for developing spin-current based electronics.

n l -> n' l' transition rates in electron and proton - Rydberg atom collision

NASA Astrophysics Data System (ADS)

Vrinceanu, Daniel

2017-04-01

Electrons and protons drive the recombination dynamics of highly excited Rydberg atoms in cold rarefied plasmas found in astrophysical conditions such as primordial recombination or star formation in H-II clouds. It has been recognized that collisions induce both energy and angular momentum transitions in Rydberg atoms, although in different proportions, depending on the initial state, temperature and the given species considered in the collision (electron or proton). Most studies focused on one collision type at a time, under the assumption that collision types are independent or their effects are not competing. The classical Monte-Carlo trajectory simulations presented in this work calculate the rates for both energy and angular momentum transfers and show their interdependence. For example, energy transfer with small angular momentum change are more efficient for target states with initial large angular momentum. The author acknowledges support received from the National Science Foundation through a Grant for the Center for Research on Complex Networks (HRD-1137732).

Controlling the spins angular momentum in ferromagnets with sequences of picosecond acoustic pulses.

PubMed

Kim, Ji-Wan; Vomir, Mircea; Bigot, Jean-Yves

2015-02-17

Controlling the angular momentum of spins with very short external perturbations is a key issue in modern magnetism. For example it allows manipulating the magnetization for recording purposes or for inducing high frequency spin torque oscillations. Towards that purpose it is essential to modify and control the angular momentum of the magnetization which precesses around the resultant effective magnetic field. That can be achieved with very short external magnetic field pulses or using intrinsically coupled magnetic structures, resulting in a transfer of spin torque. Here we show that using picosecond acoustic pulses is a versatile and efficient way of controlling the spin angular momentum in ferromagnets. Two or three acoustic pulses, generated by femtosecond laser pulses, allow suppressing or enhancing the magnetic precession at any arbitrary time by precisely controlling the delays and amplitudes of the optical pulses. A formal analogy with a two dimensional pendulum allows us explaining the complex trajectory of the magnetic vector perturbed by the acoustic pulses.

Contributions of high-altitude winds and atmospheric moment of inertia to the atmospheric angular momentum-earth rotation relationship

NASA Technical Reports Server (NTRS)

Taylor, H. A., Jr.; Mayr, H. G.; Kramer, L.

1985-01-01

For many years it has been recognized that recurrent modulations occur in the time series of the earth's rotation rate or, alternatively, the change in the length of the day (Delta-LOD). Studies relating Delta-LOD to global patterns of zonal winds have confirmed that the variability of atmospheric angular momentum (M) is of sufficient magnitude to account for a large portion of the gross periodicities observed in the earth rotation. The present investigation is concerned with the importance of the contributions of the moment of inertia and high-altitude winds to the angular momentum budget. On the basis of an analysis of the various factors, it is found that within the available data, contributions of high-altitude winds and atmospheric moment of inertia reach levels detectable in the atmospheric angular momentum budget. Nevertheless, for the period December 1978 to December 1979 these contributions are not sufficient to resolve the apparent short-term discrepancies which are evident between Delta-LOD and M.

Effects of the circularly polarized beam of linearized gravitational waves

NASA Astrophysics Data System (ADS)

Barker, W.

2017-08-01

Solutions of the linearized Einstein equations are found that describe a transversely confined beam of circularly polarized gravitational waves on a Minkowski backdrop. By evaluating the cycle-averaged stress-energy-momentum pseudotensor of Landau & Lifshitz it is found that the angular momentum density is concentrated in the ‘skin’ at the edge of the beam where the intensity falls, and that the ratio of angular momentum to energy per unit length of the beam is 2/ω , where ω is the wave frequency, as expected for a beam of spin-2 gravitons. For sharply-defined, uniform, axisymmetric beams, the induced background metric is shown to produce the gravitomagnetic field and frame-dragging effects of a gravitational solenoid, whilst the angular momentum current helically twists the space at infinite radius along the beam axis.

Creating optical near-field orbital angular momentum in a gold metasurface.

PubMed

Chen, Ching-Fu; Ku, Chen-Ta; Tai, Yi-Hsin; Wei, Pei-Kuen; Lin, Heh-Nan; Huang, Chen-Bin

2015-04-08

Nanocavities inscribed in a gold thin film are optimized and designed to form a metasurface. We demonstrate both numerically and experimentally the creation of surface plasmon (SP) vortex carrying orbital angular momentum in the metasurface under linearly polarized optical excitation that carries no optical angular momentum. Moreover, depending on the orientation of the exciting linearly polarized light, we show that the metasurface is capable of providing dynamic switching between SP vortex formation or SP subwavelength focusing. The resulting SP intensities are experimentally measured using a near-field scanning optical microscope and are found in excellent quantitative agreements as compared to the numerical results.

Orbital angular momentum (OAM) spectrum correction in free space optical communication.

PubMed

Liu, Yi-Dong; Gao, Chunqing; Qi, Xiaoqing; Weber, Horst

2008-05-12

Orbital angular momentum (OAM) of laser beams has potential application in free space optical communication, but it is sensitive against pointing instabilities of the beam, i.e. shift (lateral displacement) and tilt (deflection of the beam). This work proposes a method to correct the distorted OAM spectrum by using the mean square value of the orbital angular momentum as an indicator. Qualitative analysis is given, and the numerical simulation is carried out for demonstration. The results show that the mean square value can be used to determine the beam axis of the superimposed helical beams. The initial OAM spectrum can be recovered.

Evidence for the Absence of Gluon Orbital Angular Momentum in the Nucleon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brodsky, S.J.; Gardner, S.

2006-08-23

The Sivers mechanism for the single-spin asymmetry in unpolarized lepton scattering from a transversely polarized nucleon is driven by the orbital angular momentum carried by its quark and gluon constituents, combined with QCD final-state interactions. Both quark and gluon mechanisms can generate such a single-spin asymmetry, though only the quark mechanism can explain the small single-spin asymmetry measured by the COMPASS collaboration on the deuteron, suggesting the gluon mechanism is small relative to the quark mechanism. We detail empirical studies through which the gluon and quark orbital angular momentum contributions, quark-flavor by quark-flavor, can be elucidated.

Addition and subtraction operation of optical orbital angular momentum with dielectric metasurfaces

NASA Astrophysics Data System (ADS)

Yi, Xunong; Li, Ying; Ling, Xiaohui; Liu, Yachao; Ke, Yougang; Fan, Dianyuan

2015-12-01

In this work, we propose a simple approach to realize addition and subtraction operation of optical orbital angular momentum (OAM) based on dielectric metasurfaces. The spin-orbit interaction of light in spatially inhomogeneous and anisotropic metasurfaces results in the spin-to-orbital angular momentum conversion. The subtraction system of OAM consists of two cascaded metasurfaces, while the addition system of OAM is constituted by inserting a half waveplate (HWP) between the two metasurfaces. Our experimental results are in good agreement with the theoretical calculation. These results could be useful for OAM-carrying beams applied in optical communication, information processing, etc.

ROTATING STARS AND THE FORMATION OF BIPOLAR PLANETARY NEBULAE. II. TIDAL SPIN-UP

DOE Office of Scientific and Technical Information (OSTI.GOV)

García-Segura, G.; Villaver, E.; Manchado, A.

We present new binary stellar evolution models that include the effects of tidal forces, rotation, and magnetic torques with the goal of testing planetary nebulae (PNs) shaping via binary interaction. We explore whether tidal interaction with a companion can spin-up the asymptotic giant brach (AGB) envelope. To do so, we have selected binary systems with main-sequence masses of 2.5 M {sub ⊙} and 0.8 M {sub ⊙} and evolve them allowing initial separations of 5, 6, 7, and 8 au. The binary stellar evolution models have been computed all the way to the PNs formation phase or until Roche lobemore » overflow (RLOF) is reached, whatever happens first. We show that with initial separations of 7 and 8 au, the binary avoids entering into RLOF, and the AGB star reaches moderate rotational velocities at the surface (∼3.5 and ∼2 km s{sup −1}, respectively) during the inter-pulse phases, but after the thermal pulses it drops to a final rotational velocity of only ∼0.03 km s{sup −1}. For the closest binary separations explored, 5 and 6 au, the AGB star reaches rotational velocities of ∼6 and ∼4 km s{sup −1}, respectively, when the RLOF is initiated. We conclude that the detached binary models that avoid entering the RLOF phase during the AGB will not shape bipolar PNs, since the acquired angular momentum is lost via the wind during the last two thermal pulses. This study rules out tidal spin-up in non-contact binaries as a sufficient condition to form bipolar PNs.« less

Coherent π-electron dynamics of (P)-2,2'-biphenol induced by ultrashort linearly polarized UV pulses: Angular momentum and ring current

NASA Astrophysics Data System (ADS)

Mineo, H.; Lin, S. H.; Fujimura, Y.

2013-02-01

The results of a theoretical investigation of coherent π-electron dynamics for nonplanar (P)-2,2'-biphenol induced by ultrashort linearly polarized UV pulses are presented. Expressions for the time-dependent coherent angular momentum and ring current are derived by using the density matrix method. The time dependence of these coherences is determined by the off-diagonal density matrix element, which can be obtained by solving the coupled equations of motion of the electronic-state density matrix. Dephasing effects on coherent angular momentum and ring current are taken into account within the Markov approximation. The magnitudes of the electronic angular momentum and current are expressed as the sum of expectation values of the corresponding operators in the two phenol rings (L and R rings). Here, L (R) denotes the phenol ring in the left (right)-hand side of (P)-2,2'-biphenol. We define the bond current between the nearest neighbor carbon atoms Ci and Cj as an electric current through a half plane perpendicular to the Ci-Cj bond. The bond current can be expressed in terms of the inter-atomic bond current. The inter-atomic bond current (bond current) depends on the position of the half plane on the bond and has the maximum value at the center. The coherent ring current in each ring is defined by averaging over the bond currents. Since (P)-2,2'-biphenol is nonplanar, the resultant angular momentum is not one-dimensional. Simulations of the time-dependent coherent angular momentum and ring current of (P)-2,2'-biphenol excited by ultrashort linearly polarized UV pulses are carried out using the molecular parameters obtained by the time-dependent density functional theory (TD-DFT) method. Oscillatory behaviors in the time-dependent angular momentum (ring current), which can be called angular momentum (ring current) quantum beats, are classified by the symmetry of the coherent state, symmetric or antisymmetric. The bond current of the bridge bond linking the L and R rings is zero for the symmetric coherent state, while it is nonzero for the antisymmetric coherent state. The magnitudes of ring current and ring current-induced magnetic field are also evaluated, and their possibility as a control parameter in ultrafast switching devices is discussed. The present results give a detailed description of the theoretical treatment reported in our previous paper [H. Mineo, M. Yamaki, Y. Teranish, M. Hayashi, S. H. Lin, and Y. Fujimura, J. Am. Chem. Soc. 134, 14279 (2012), 10.1021/ja3047848].

Kinetic theory of twisted waves: Application to space plasmas having superthermal population of species

NASA Astrophysics Data System (ADS)

Arshad, Kashif; Poedts, Stefaan; Lazar, Marian

2017-04-01

Nowadays electromagnetic (EM) fields have various applications in fundamental research, communication, and home appliances. Even though, there are still some subtle features of electromagnetic field known to us a century ago, yet to be utilized. It is because of the technical complexities to sense three dimensional electromagnetic field. An important characteristic of electromagnetic field is its orbital angular momentum (OAM). The angular momentum consists of two distinct parts; intrinsic part associated with the wave polarization or spin, and the extrinsic part associated with the orbital angular momentum (OAM). The orbital angular momentum (OAM) is inherited by helically phased light or helical (twisted) electric field. The investigations of Allen on lasers carrying orbital angular momentum (OAM), has initiated a new scientific and technological advancement in various growing fields, such as microscopy and imaging, atomic and nano-particle manipulation, ultra-fast optical communications, quantum computing, ionospheric radar facility to observe 3D plasma dynamics in ionosphere, photonic crystal fibre, OAM entanglement of two photons, twisted gravitational waves, ultra-intense twisted laser pulses and astrophysics. Recently, the plasma modes are also investigated with orbital angular momentum. The production of electron vortex beams and its applications are indicated by Verbeeck et al. The magnetic tornadoes (rotating magnetic field structures) exhibit three types of morphology i.e., spiral, ring and split. Leyser pumped helical radio beam carrying OAM into the Ionospheric plasma under High Frequency Active Auroral Research Program (HAARP) and characteristic ring shaped morphology is obtained by the optical emission spectrum of pumped plasma turbulence. The scattering phenomenon like (stimulated Raman and Brillouin backscattering) is observed to be responsible for the interaction between electrostatic and electromagnetic waves through orbital angular momentum. The ring shape morphology of a beam with orbital angular momentum (OAM) is ideal for the observation of solar corona around the sun where the intensity of the beam is minimum at the center, in solar experiments, and Earth's ionosphere. The twisted plasma modes carrying OAM are mostly studied either by the fluid theory or Maxwellian distributed Kinetic Theory. But most of the space plasmas and some laboratory plasmas have non-thermal distributions due to super-thermal population of the plasma particles. Therefore the Kinetic Theory of twisted plasma modes carrying OAM are recently studied using non-thermal (kappa) distribution of the super-thermal particles in the presence of the helical electric field and significant change in the damping rates are observed by tuning appropriate parameters.

Coherent π-electron dynamics of (P)-2,2'-biphenol induced by ultrashort linearly polarized UV pulses: angular momentum and ring current.

PubMed

Mineo, H; Lin, S H; Fujimura, Y

2013-02-21

The results of a theoretical investigation of coherent π-electron dynamics for nonplanar (P)-2,2'-biphenol induced by ultrashort linearly polarized UV pulses are presented. Expressions for the time-dependent coherent angular momentum and ring current are derived by using the density matrix method. The time dependence of these coherences is determined by the off-diagonal density matrix element, which can be obtained by solving the coupled equations of motion of the electronic-state density matrix. Dephasing effects on coherent angular momentum and ring current are taken into account within the Markov approximation. The magnitudes of the electronic angular momentum and current are expressed as the sum of expectation values of the corresponding operators in the two phenol rings (L and R rings). Here, L (R) denotes the phenol ring in the left (right)-hand side of (P)-2,2'-biphenol. We define the bond current between the nearest neighbor carbon atoms Ci and Cj as an electric current through a half plane perpendicular to the Ci-Cj bond. The bond current can be expressed in terms of the inter-atomic bond current. The inter-atomic bond current (bond current) depends on the position of the half plane on the bond and has the maximum value at the center. The coherent ring current in each ring is defined by averaging over the bond currents. Since (P)-2,2'-biphenol is nonplanar, the resultant angular momentum is not one-dimensional. Simulations of the time-dependent coherent angular momentum and ring current of (P)-2,2'-biphenol excited by ultrashort linearly polarized UV pulses are carried out using the molecular parameters obtained by the time-dependent density functional theory (TD-DFT) method. Oscillatory behaviors in the time-dependent angular momentum (ring current), which can be called angular momentum (ring current) quantum beats, are classified by the symmetry of the coherent state, symmetric or antisymmetric. The bond current of the bridge bond linking the L and R rings is zero for the symmetric coherent state, while it is nonzero for the antisymmetric coherent state. The magnitudes of ring current and ring current-induced magnetic field are also evaluated, and their possibility as a control parameter in ultrafast switching devices is discussed. The present results give a detailed description of the theoretical treatment reported in our previous paper [H. Mineo, M. Yamaki, Y. Teranish, M. Hayashi, S. H. Lin, and Y. Fujimura, J. Am. Chem. Soc. 134, 14279 (2012)].

Lunar and Solar Torques on the Oceanic Tides

NASA Technical Reports Server (NTRS)

Ray, Richard D.; Bills, Bruce G.; Chao, Benjamin F.

1998-01-01

Brosche and Seiler recently suggested that direct lunar and solar tidal torques on the oceanic tides play a significant role in the earth's short-period angular momentum balance ("short-period" here meaning daily and sub-daily). We reexamine that suggestion here, concentrating on axial torques and hence on variations in rotation rate. Only those spherical harmonic components of the ocean tide having the same degree and order as the tidal potential induce nonzero torques. Prograde components (those moving in the same direction as the tide-generating body) produce the familiar secular braking of the earth's rotation. Retrograde components, however, produce rapid variations in UTI at twice the tidal frequency. There also exist interaction torques between tidal constituents, e.g. solar torques on lunar tides. They generate UTI variations at frequencies equal to the sums and differences of the original tidal frequencies. We give estimates of the torques and angular momentum variations for each of the important regimes, secular to quarter-diurnal. For the M(sub 2) potential acting on the M(sub 2) ocean tide, we find an associated angular momentum variation of amplitude 3 x 10(exp 19) N m. This is 5 to 6 orders of magnitude smaller than the angular momentum variations associated with tidal currents. We conclude that these torques do not play a significant role in the short-period angular momentum balance.

High Angular Momentum Halo Gas: A Feedback and Code-independent Prediction of LCDM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stewart, Kyle R.; Maller, Ariyeh H.; Oñorbe, Jose

We investigate angular momentum acquisition in Milky Way-sized galaxies by comparing five high resolution zoom-in simulations, each implementing identical cosmological initial conditions but utilizing different hydrodynamic codes: Enzo, Art, Ramses, Arepo, and Gizmo-PSPH. Each code implements a distinct set of feedback and star formation prescriptions. We find that while many galaxy and halo properties vary between the different codes (and feedback prescriptions), there is qualitative agreement on the process of angular momentum acquisition in the galaxy’s halo. In all simulations, cold filamentary gas accretion to the halo results in ∼4 times more specific angular momentum in cold halo gas (more » λ {sub cold} ≳ 0.1) than in the dark matter halo. At z > 1, this inflow takes the form of inspiraling cold streams that are co-directional in the halo of the galaxy and are fueled, aligned, and kinematically connected to filamentary gas infall along the cosmic web. Due to the qualitative agreement among disparate simulations, we conclude that the buildup of high angular momentum halo gas and the presence of these inspiraling cold streams are robust predictions of Lambda Cold Dark Matter galaxy formation, though the detailed morphology of these streams is significantly less certain. A growing body of observational evidence suggests that this process is borne out in the real universe.« less

Spin force and torque in non-relativistic Dirac oscillator on a sphere

NASA Astrophysics Data System (ADS)

Shikakhwa, M. S.

2018-03-01

The spin force operator on a non-relativistic Dirac oscillator (in the non-relativistic limit the Dirac oscillator is a spin one-half 3D harmonic oscillator with strong spin-orbit interaction) is derived using the Heisenberg equations of motion and is seen to be formally similar to the force by the electromagnetic field on a moving charged particle. When confined to a sphere of radius R, it is shown that the Hamiltonian of this non-relativistic oscillator can be expressed as a mere kinetic energy operator with an anomalous part. As a result, the power by the spin force and torque operators in this case are seen to vanish. The spin force operator on the sphere is calculated explicitly and its torque is shown to be equal to the rate of change of the kinetic orbital angular momentum operator, again with an anomalous part. This, along with the conservation of the total angular momentum, suggests that the spin force exerts a spin-dependent torque on the kinetic orbital angular momentum operator in order to conserve total angular momentum. The presence of an anomalous spin part in the kinetic orbital angular momentum operator gives rise to an oscillatory behavior similar to the Zitterbewegung. It is suggested that the underlying physics that gives rise to the spin force and the Zitterbewegung is one and the same in NRDO and in systems that manifest spin Hall effect.

A Collapsar Model with Disk Wind: Implications for Supernovae Associated with Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Hayakawa, Tomoyasu; Maeda, Keiichi

2018-02-01

We construct a simple but self-consistent collapsar model for gamma-ray bursts (GRBs) and SNe associated with GRBs (GRB-SNe). Our model includes a black hole, an accretion disk, and the envelope surrounding the central system. The evolutions of the different components are connected by the transfer of the mass and angular momentum. To address properties of the jet and the wind-driven SNe, we consider competition of the ram pressure from the infalling envelope and those from the jet and wind. The expected properties of the GRB jet and the wind-driven SN are investigated as a function of the progenitor mass and angular momentum. We find two conditions that should be satisfied if the wind-driven explosion is to explain the properties of the observed GRB-SNe: (1) the wind should be collimated at its base, and (2) it should not prevent further accretion even after the launch of the SN explosion. Under these conditions, some relations seen in the properties of the GRB-SNe could be reproduced by a sequence of different angular momentum in the progenitors. Only the model with the largest angular momentum could explain the observed (energetic) GRB-SNe, and we expect that the collapsar model can result in a wide variety of observational counterparts, mainly depending on the angular momentum of the progenitor star.

Muscle Contributions to Frontal Plane Angular Momentum during Walking

PubMed Central

Neptune, Richard R.; McGowan, Craig P.

2016-01-01

The regulation of whole-body angular momentum is important for maintaining dynamic balance during human walking, which is particularly challenging in the frontal plane. Whole-body angular momentum is actively regulated by individual muscle forces. Thus, understanding which muscles contribute to frontal plane angular momentum will further our understanding of mediolateral balance control and has the potential to help diagnose and treat balance disorders. The purpose of this study was to identify how individual muscles and gravity contribute to whole-body angular momentum in the frontal plane using a muscle-actuated forward dynamics simulation analysis. A three-dimensional simulation was developed that emulated the average walking mechanics of a group of young healthy adults (n=10). The results showed that a finite set of muscles are the primary contributors to frontal plane balance and that these contributions vary throughout the gait cycle. In early stance, the vasti, adductor magnus and gravity acted to rotate the body towards the contralateral leg while the gluteus medius acted to rotate the body towards the ipsilateral leg. In late stance, the gluteus medius continued to rotate the body towards the ipsilateral leg while the soleus and gastrocnemius acted to rotate the body towards the contralateral leg. These results highlight those muscles that are critical to maintaining dynamic balance in the frontal plane during walking and may provide targets for locomotor therapies aimed at treating balance disorders. PMID:27522538

Control of the Spin Angular Momentum and Orbital Angular Momentum of a Reflected Wave by Multifunctional Graphene Metasurfaces.

PubMed

Zhang, Chen; Deng, Li; Zhu, Jianfeng; Hong, Weijun; Wang, Ling; Yang, Wenjie; Li, Shufang

2018-06-21

Three kinds of multifunctional graphene metasurfaces based on Pancharatnam⁻Berry (PB) phase cells are proposed and numerically demonstrated to control a reflected wave’s spin angular momentum (SAM) and orbital angular momentum (OAM) in the terahertz (THz) regime. Each proposed metasurface structure is composed of an array of graphene strips with different deviation angles and a back-grounded quartz substrate. In order to further help readers have a deeper insight into the graphene-based metasurfaces, a detailed design strategy is also provided. With the aid of the designed graphene elements, the proposed metasurfaces can achieve the full 360° range of phase coverage and provide manipulation of SAM and OAM of a circularly polarized (CP) wave at will. More importantly, simultaneous control of these two momentums can also be realized, and in order to demonstrate this function, a THz spin-controlled OAM beam generator with diverse topological charges is created, which can provide one more degree of freedom to improve the channel capability without increasing the bandwidth compared to a linearly polarized (LP) OAM beam. Numerical results verify the proposed graphene metasurfaces, which pave the way for generating spin OAM vortex waves for THz communication systems.

Scale dependencies of proton spin constituents with a nonperturbative αs

NASA Astrophysics Data System (ADS)

Jia, Shaoyang; Huang, Feng

2012-11-01

By introducing the contribution from dynamically generated gluon mass, we present a brand new parametrized form of QCD beta function to get an inferred limited running behavior of QCD coupling constant αs. This parametrized form is regarded as an essential factor to determine the scale dependencies of the proton spin constituents at the very low scale. In order to compare with experimental results directly, we work within the gauge-invariant framework to decompose the proton spin. Utilizing the updated next-to-next-leading-order evolution equations for angular momentum observables within a modified minimal subtraction scheme, we indicate that gluon contribution to proton spin cannot be ignored. Specifically, by assuming asymptotic limits of the total quark/gluon angular momentum valid, respectively, the scale dependencies of quark angular momentum Jq and gluon angular momentum Jg down to Q2˜1GeV2 are presented, which are comparable with the preliminary analysis of deeply virtual Compton scattering experiments by HERMES and JLab. After solving scale dependencies of quark spin ΔΣq, orbital angular momenta of quarks Lq are given by subtraction, presenting a holistic picture of proton spin partition within up and down quarks at a low scale.

Probing transverse momentum broadening via jet-related angular correlations in relativistic nuclear collisions

NASA Astrophysics Data System (ADS)

Chen, Lin; Qin, Guang-You; Wei, Shu-Yi; Xiao, Bo-Wen; Zhang, Han-Zhong

2017-11-01

Jet-related correlations have been regarded as important tools for studying jet-medium interaction and jet quenching in relativistic heavy-ion collisions at RHIC and the LHC. Here we present our recent work [L. Chen, G.-Y. Qin, S.-Y. Wei, B.-W. Xiao, H.-Z. Zhang, Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions, arxiv:arXiv:1607.01932] and show that the back-to-back angular correlations in dijet, dihadron and hadron-jet measurements can be utilized as a quantitative tool to probe the medium-induced transverse momentum broadening and to extract jet quenching parameter q̂. By comparing with the dihadron and hadron-jet angular correlation data at RHIC, we obtain the medium-induced transverse momentum broadening, averaged over different jet paths, 〈 p⊥2 〉 ∼ 13 GeV2 for a quark jet in most central Au-Au collisions at 200A GeV. Future experiments with statistically improved data on jet-related (angular) correlations will allow us to obtain more precise knowledge of jet quenching parameter and parton-medium interaction in high-energy nuclear collisions.

Hot subdwarf stars in close-up view. II. Rotational properties of single and wide binary subdwarf B stars

NASA Astrophysics Data System (ADS)

Geier, S.; Heber, U.

2012-07-01

Subluminous B stars (sdBs) form the extremely hot end of the horizontal branch and are therefore related to the blue horizontal branch (BHB) stars. While the rotational properties of BHB stars have been investigated extensively, studies of sdB stars have concentrated on close binaries that are influenced by tidal interactions between their components. Here we present a study of 105 sdB stars, which are either single stars or in wide binaries where tidal effects become negligible. The projected rotational velocities have been determined by measuring the broadening of metal lines using high-resolution optical spectra. All stars in our sample are slow rotators (vrotsini < 10 km s-1). Furthermore, the vrotsini-distributions of single sdBs are similar to those of hot subdwarfs in wide binaries with main-sequence companions as well as close binary systems with unseen companions and periods exceeding ≃1.2 d. We show that blue horizontal and extreme horizontal branch stars are also related in terms of surface rotation and angular momentum. Hot BHB stars (Teff > 11 500 K) with diffusion-dominated atmospheres are slow rotators like the hot subdwarf stars located on the extreme horizontal branch, which lost more envelope and therefore angular momentum in the red-giant phase. The uniform rotation distributions of single and wide binary sdBs pose a challenge to our understanding of hot subdwarf formation. Especially the high fraction of helium white dwarf mergers predicted by theory seems to be inconsistent with the results presented here. Based on observations at the Paranal Observatory of the European Southern Observatory for programmes number 165.H-0588(A), 167.D-0407(A), 071.D-0380(A) and 072.D-0487(A). Based on observations at the La Silla Observatory of the European Southern Observatory for programmes number 073.D-0495(A), 074.B-0455(A), 076.D-0355(A), 077.D-0515(A) and 078.D-0098(A). Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). Some of the data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Based on data obtained with the Hobby-Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

Diagnostic Studies With GLA Fields

NASA Technical Reports Server (NTRS)

Salstein, David A.

1997-01-01

Assessments of the NASA Goddard Earth Observing System-1 Data Assimilation System (GEOS-1 DAS) regarding heating rates, energetics and angular momentum quantities were made. These diagnostics can be viewed as measures of climate variability. Comparisons with the NOAA/NCEP reanalysis system of momentum and energetics diagnostics are included. Water vapor and angular momentum are diagnosed in many models, including those of NASA, as part of the Atmospheric Model Intercomparison Project. Relevant preprints are included herein.

The light-front gauge-invariant energy-momentum tensor

DOE PAGES

Lorce, Cedric

2015-08-11

In this study, we provide for the first time a complete parametrization for the matrix elements of the generic asymmetric, non-local and gauge-invariant canonical energy-momentum tensor, generalizing therefore former works on the symmetric, local and gauge-invariant kinetic energy-momentum tensor also known as the Belinfante-Rosenfeld energy-momentum tensor. We discuss in detail the various constraints imposed by non-locality, linear and angular momentum conservation. We also derive the relations with two-parton generalized and transverse-momentum dependent distributions, clarifying what can be learned from the latter. In particular, we show explicitly that two-parton transverse-momentum dependent distributions cannot provide any model-independent information about the parton orbitalmore » angular momentum. On the way, we recover the Burkardt sum rule and obtain similar new sum rules for higher-twist distributions.« less

Novel Detection of Optical Orbital Angular Momentum

DTIC Science & Technology

2014-11-16

spin-orbit coupling at single- photon entanglement and quantum transfer as well as their combinations. Some studies exist on hybrid entanglement . 3.1... Entanglement of the orbital angular momentum states of photons ,” Nature, 412, 313-316 (2001). [9]. D. J. Sanchez and D. W. Oesch, “Orbital angular... photon with no change in its OAM states among traveling inside the atmosphere. Both studies assume only a phase distortion causes by the atmospheric

An Anzatz about Gravity, Cosmology, and the Pioneer Anomaly

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murad, Paul

2010-01-28

The Pulsar 1913+16 binary system may represent a 'young' binary system where previously it is claimed that the dynamics are due to either a third body or a gravitational vortex. Usually a binary system's trajectory could reside in a single ellipse or circular orbit; the double ellipse implies that the 1913+16 system may be starting to degenerate into a single elliptical trajectory. This could be validated only after a considerably long time period. In a majority of binary star systems, the weights of both stars are claimed by analysis to be the same. It may be feasible that the trajectorymore » of the primary spinning star could demonstrate repulsive gravitational effects where the neutron star's high spin rate induces a repulsive gravitational source term that compensates for inertia. If true, then it provides evidence that angular momentum may be translated into linear momentum as a repulsive source that has propulsion implications. This also suggests mass differences may dictate the neutron star's spin rate as an artifact of a natural gravitational process. Moreover, the reduced matter required by the 'dark' mass hypothesis may not exist but these effects could be due to repulsive gravity residing in rotating celestial bodies.The Pioneer anomaly observed on five different deep-space spacecraft, is the appearance of a constant gravitational force directed toward the sun. Pioneer spacecraft data reveals that a vortex-like magnetic field exists emanating from the sun. The spiral arms of the Sun's magnetic vortex field may be causal to this constant acceleration. This may profoundly provide a possible experimental verification on a cosmic scale of Gertsenshtein's principle relating gravity to electromagnetism. Furthermore, the anomalous acceleration may disappear once the spacecraft passes out into a magnetic spiral furrow, which is something that needs to be observed in the future. Other effects offer an explanation from space-time geometry to the Yarkovsky thermal effects are discussed.« less

Improving Student Understanding of Addition of Angular Momentum in Quantum Mechanics

ERIC Educational Resources Information Center

Zhu, Guangtian; Singh, Chandralekha

2013-01-01

We describe the difficulties advanced undergraduate and graduate students have with concepts related to addition of angular momentum in quantum mechanics. We also describe the development and implementation of a research-based learning tool, Quantum Interactive Learning Tutorial (QuILT), to reduce these difficulties. The preliminary evaluation…

Angular Momentum

ERIC Educational Resources Information Center

Shakur, Asif; Sinatra, Taylor

2013-01-01

The gyroscope in a smartphone was employed in a physics laboratory setting to verify the conservation of angular momentum and the nonconservation of rotational kinetic energy. As is well-known, smartphones are ubiquitous on college campuses. These devices have a panoply of built-in sensors. This creates a unique opportunity for a new paradigm in…

On the origin of the angular momentum of galaxies: cosmological tidal torques supplemented by the Coriolis force

NASA Astrophysics Data System (ADS)

Casuso, E.; Beckman, J. E.

2015-05-01

We present here a theoretical model which can at least contribute to the observed relation between the specific angular momenta of galaxies and their masses. This study offers prima facie evidence that the origin of an angular momentum of galaxies could be somewhat more complex than previously proposed. The most recent observations point to a scenario in which, after recombination, matter was organized around bubbles (commonly termed voids), which acquired rotation by tidal torque interaction. Subsequently, a combination of the effects of the gravitational collapse of gas in protogalaxies and the Coriolis force due to the rotation of the voids could produce the rotation of spiral galaxies. Thereafter, the tidal interaction between the objects populating the quasi-spherical voids, in which the galaxies far away from the rotation axes (populating the sheet forming the surface of a void) interact with higher probability with others similarly situated in a neighbouring void, offers a mechanism for transforming some of the galaxies into ellipticals, breaking their spin and yielding galaxies with low net angular momentum, as observed. This model gives an explanation for those observations which suggest a tendency of galactic spins to align along the radius vectors pointing towards the centres of the voids for ellipticals/SO and parallel to filaments and sheets for the spirals. Furthermore, while in simple tidal torque theory the angular momentum supplied to galaxies diminishes drastically with the cosmic expansion, in our approximation for which the Coriolis force acts in addition to tidal torques, the Coriolis force due to void rotation ensures almost continuous angular momentum supply.

The SW Sex Phenomenon as an Evolutionary Stage of Cataclysmic Variables

NASA Astrophysics Data System (ADS)

Schmidtobreick, L.

From recent large observing campaigns, one finds that nearly all non- or weakly magnetic cataclysmic variables in the orbital period range between 2.8 and 4 hours are of SW Sex type and as such experience very high mass transfer rates. The evolution of cataclysmic variables as for any interacting binary is driven by angular momentum loss which results in a decrease of the orbital period on evolutionary time scales. In particular, all long-period systems need to cross the SW Sex regime of the orbital period distribution before entering the period gap. This makes the SW Sex phenomenon an evolutionary stage in the life of a cataclysmic variable. Here, I present a short overview of the current state of research on these systems.

Collapse of magnetized hypermassive neutron stars in general relativity.

PubMed

Duez, Matthew D; Liu, Yuk Tung; Shapiro, Stuart L; Shibata, Masaru; Stephens, Branson C

2006-01-27

Hypermassive neutron stars (HMNSs)--equilibrium configurations supported against collapse by rapid differential rotation--are possible transient remnants of binary neutron-star mergers. Using newly developed codes for magnetohydrodynamic simulations in dynamical spacetimes, we are able to track the evolution of a magnetized HMNS in full general relativity for the first time. We find that secular angular momentum transport due to magnetic braking and the magnetorotational instability results in the collapse of an HMNS to a rotating black hole, accompanied by a gravitational wave burst. The nascent black hole is surrounded by a hot, massive torus undergoing quasistationary accretion and a collimated magnetic field. This scenario suggests that HMNS collapse is a possible candidate for the central engine of short gamma-ray bursts.

Uncertainty relations for angular momentum eigenstates in two and three spatial dimensions

NASA Astrophysics Data System (ADS)

Bracher, Christian

2011-03-01

I reexamine Heisenberg's uncertainty relation for two- and three-dimensional wave packets with fixed angular momentum quantum numbers m or ℓ. A simple proof shows that the product of the average extent Δr and Δp of a two-dimensional wave packet in position and momentum space is bounded from below by ΔrΔp ≥ℏ(|m|+1). The minimum uncertainty is attained by modified Gaussian wave packets that are special eigenstates of the two-dimensional isotropic harmonic oscillator, which include the ground states of electrons in a uniform magnetic field. Similarly, the inequality ΔrΔp ≥ℏ(ℓ +3/2) holds for three-dimensional wave packets with fixed total angular momentum ℓ and the equality holds for a Gaussian radial profile. I also discuss some applications of these uncertainty relations.

Measurement of W boson angular distributions in events with high transverse momentum jets at √{ s} = 8 TeV using the ATLAS detector

NASA Astrophysics Data System (ADS)

Aaboud, M.; Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; Aben, R.; Abouzeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; Åkesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Ali, B.; Aliev, M.; Alimonti, G.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allen, B. W.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Alshehri, A. A.; Alstaty, M.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antel, C.; Antonelli, M.; Antonov, A.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Armitage, L. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baak, M. A.; Baas, A. E.; Baca, M. J.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Baines, J. T.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balestri, T.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisits, M.-S.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska-Blenessy, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barranco Navarro, L.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bedognetti, M.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, J. K.; Belanger-Champagne, C.; Bell, A. S.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Belyaev, N. L.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez, J.; Benjamin, D. P.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Beringer, J.; Berlendis, S.; Bernard, N. R.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertram, I. A.; Bertsche, C.; Bertsche, D.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethani, A.; Bethke, S.; Bevan, A. J.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Biedermann, D.; Bielski, R.; Biesuz, N. V.; Biglietti, M.; Bilbao de Mendizabal, J.; Billoud, T. R. V.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biondi, S.; Bisanz, T.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J.-B.; Blazek, T.; Bloch, I.; Blocker, C.; Blue, A.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Boerner, D.; Bogaerts, J. A.; Bogavac, D.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bokan, P.; Bold, T.; Boldyrev, A. S.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Bortfeldt, J.; Bortoletto, D.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Bossio Sola, J. D.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Boutle, S. K.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Broughton, J. H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Bruni, A.; Bruni, G.; Bruni, L. S.; Brunt, Bh; Bruschi, M.; Bruscino, N.; Bryant, P.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Buehrer, F.; Bugge, M. K.; Bulekov, O.; Bullock, D.; Burckhart, H.; Burdin, S.; Burgard, C. D.; Burghgrave, B.; Burka, K.; Burke, S.; Burmeister, I.; Burr, J. T. P.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Cabrera Urbán, S.; Caforio, D.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Callea, G.; Caloba, L. P.; Calvente Lopez, S.; Calvet, D.; Calvet, S.; Calvet, T. P.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Camincher, C.; Campana, S.; Campanelli, M.; Camplani, A.; Campoverde, A.; Canale, V.; Canepa, A.; Cano Bret, M.; Cantero, J.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, I.; Carli, T.; Carlino, G.; Carminati, L.; Carney, R. M. D.; Caron, S.; Carquin, E.; Carrillo-Montoya, G. D.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Casper, D. W.; Castaneda-Miranda, E.; Castelijn, R.; Castelli, A.; Castillo Gimenez, V.; Castro, N. F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavallaro, E.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Ceradini, F.; Cerda Alberich, L.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cerv, M.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chan, S. K.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chatterjee, A.; Chau, C. C.; Chavez Barajas, C. A.; Che, S.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, K.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, H. J.; Cheng, Y.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Chevalier, L.; Chiarella, V.; Chiarelli, G.; Chiodini, G.; Chisholm, A. S.; Chitan, A.; Chizhov, M. V.; Choi, K.; Chomont, A. R.; Chouridou, S.; Chow, B. K. B.; Christodoulou, V.; Chromek-Burckhart, D.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciapetti, G.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Cioara, I. A.; Ciocca, C.; Ciocio, A.; Cirotto, F.; Citron, Z. H.; Citterio, M.; Ciubancan, M.; Clark, A.; Clark, B. L.; Clark, M. R.; Clark, P. J.; Clarke, R. N.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Colasurdo, L.; Cole, B.; Colijn, A. P.; Collot, J.; Colombo, T.; Compostella, G.; Conde Muiño, P.; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Consorti, V.; Constantinescu, S.; Conti, G.; Conventi, F.; Cooke, M.; Cooper, B. D.; Cooper-Sarkar, A. M.; Cormier, K. J. R.; Cornelissen, T.; Corradi, M.; Corriveau, F.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Cottin, G.; Cowan, G.; Cox, B. E.; Cranmer, K.; Crawley, S. J.; Cree, G.; Crépé-Renaudin, S.; Crescioli, F.; Cribbs, W. A.; Crispin Ortuzar, M.; Cristinziani, M.; Croft, V.; Crosetti, G.; Cueto, A.; Cuhadar Donszelmann, T.; Cummings, J.; Curatolo, M.; Cúth, J.; Czirr, H.; Czodrowski, P.; D'Amen, G.; D'Auria, S.; D'Onofrio, M.; da Cunha Sargedas de Sousa, M. J.; da Via, C.; Dabrowski, W.; Dado, T.; Dai, T.; Dale, O.; Dallaire, F.; Dallapiccola, C.; Dam, M.; Dandoy, J. R.; Dang, N. P.; Daniells, A. C.; Dann, N. S.; Danninger, M.; Dano Hoffmann, M.; Dao, V.; Darbo, G.; Darmora, S.; Dassoulas, J.; Dattagupta, A.; Davey, W.; David, C.; Davidek, T.; Davies, M.; Davison, P.; Dawe, E.; Dawson, I.; de, K.; de Asmundis, R.; de Benedetti, A.; de Castro, S.; de Cecco, S.; de Groot, N.; de Jong, P.; de la Torre, H.; de Lorenzi, F.; de Maria, A.; de Pedis, D.; de Salvo, A.; de Sanctis, U.; de Santo, A.; de Vivie de Regie, J. B.; Dearnaley, W. J.; Debbe, R.; Debenedetti, C.; Dedovich, D. V.; Dehghanian, N.; Deigaard, I.; Del Gaudio, M.; Del Peso, J.; Del Prete, T.; Delgove, D.; Deliot, F.; Delitzsch, C. M.; Dell'Acqua, A.; Dell'Asta, L.; Dell'Orso, M.; Della Pietra, M.; Della Volpe, D.; Delmastro, M.; Delsart, P. A.; Demarco, D. A.; Demers, S.; Demichev, M.; Demilly, A.; Denisov, S. P.; Denysiuk, D.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Deterre, C.; Dette, K.; Deviveiros, P. O.; Dewhurst, A.; Dhaliwal, S.; di Ciaccio, A.; di Ciaccio, L.; di Clemente, W. K.; di Donato, C.; di Girolamo, A.; di Girolamo, B.; di Micco, B.; di Nardo, R.; di Simone, A.; di Sipio, R.; di Valentino, D.; Diaconu, C.; Diamond, M.; Dias, F. A.; Diaz, M. A.; Diehl, E. B.; Dietrich, J.; Díez Cornell, S.; Dimitrievska, A.; Dingfelder, J.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djobava, T.; Djuvsland, J. I.; Do Vale, M. A. B.; Dobos, D.; Dobre, M.; Doglioni, C.; Dolejsi, J.; Dolezal, Z.; Donadelli, M.; Donati, S.; Dondero, P.; Donini, J.; Dopke, J.; Doria, A.; Dova, M. T.; Doyle, A. T.; Drechsler, E.; Dris, M.; Du, Y.; Duarte-Campderros, J.; Duchovni, E.; Duckeck, G.; Ducu, O. A.; Duda, D.; Dudarev, A.; Chr. Dudder, A.; Duffield, E. M.; Duflot, L.; Dührssen, M.; Dumancic, M.; Dunford, M.; Duran Yildiz, H.; Düren, M.; Durglishvili, A.; Duschinger, D.; Dutta, B.; Dyndal, M.; Eckardt, C.; Ecker, K. M.; Edgar, R. C.; Edwards, N. C.; Eifert, T.; Eigen, G.; Einsweiler, K.; Ekelof, T.; El Kacimi, M.; Ellajosyula, V.; Ellert, M.; Elles, S.; Ellinghaus, F.; Elliot, A. A.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Emeliyanov, D.; Enari, Y.; Endner, O. C.; Ennis, J. S.; Erdmann, J.; Ereditato, A.; Ernis, G.; Ernst, J.; Ernst, M.; Errede, S.; Ertel, E.; Escalier, M.; Esch, H.; Escobar, C.; Esposito, B.; Etienvre, A. I.; Etzion, E.; Evans, H.; Ezhilov, A.; Ezzi, M.; Fabbri, F.; Fabbri, L.; Facini, G.; Fakhrutdinov, R. M.; Falciano, S.; Falla, R. J.; Faltova, J.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farina, C.; Farina, E. M.; Farooque, T.; Farrell, S.; Farrington, S. M.; Farthouat, P.; Fassi, F.; Fassnacht, P.; Fassouliotis, D.; Faucci Giannelli, M.; Favareto, A.; Fawcett, W. J.; Fayard, L.; Fedin, O. L.; Fedorko, W.; Feigl, S.; Feligioni, L.; Feng, C.; Feng, E. J.; Feng, H.; Fenyuk, A. B.; Feremenga, L.; Fernandez Martinez, P.; Fernandez Perez, S.; Ferrando, J.; Ferrari, A.; Ferrari, P.; Ferrari, R.; Ferreira de Lima, D. E.; Ferrer, A.; Ferrere, D.; Ferretti, C.; Ferretto Parodi, A.; Fiedler, F.; Filipčič, A.; Filipuzzi, M.; Filthaut, F.; Fincke-Keeler, M.; Finelli, K. D.; Fiolhais, M. C. N.; Fiorini, L.; Firan, A.; Fischer, A.; Fischer, C.; Fischer, J.; Fisher, W. C.; Flaschel, N.; Fleck, I.; Fleischmann, P.; Fletcher, G. T.; Fletcher, R. R. M.; Flick, T.; Flores Castillo, L. R.; Flowerdew, M. J.; Forcolin, G. T.; Formica, A.; Forti, A.; Foster, A. G.; Fournier, D.; Fox, H.; Fracchia, S.; Francavilla, P.; Franchini, M.; Francis, D.; Franconi, L.; Franklin, M.; Frate, M.; Fraternali, M.; Freeborn, D.; Fressard-Batraneanu, S. M.; Friedrich, F.; Froidevaux, D.; Frost, J. A.; Fukunaga, C.; Fullana Torregrosa, E.; Fusayasu, T.; Fuster, J.; Gabaldon, C.; Gabizon, O.; Gabrielli, A.; Gabrielli, A.; Gach, G. P.; Gadatsch, S.; Gadomski, S.; Gagliardi, G.; Gagnon, L. G.; Gagnon, P.; Galea, C.; Galhardo, B.; Gallas, E. J.; Gallop, B. J.; Gallus, P.; Galster, G.; Gan, K. K.; Ganguly, S.; Gao, J.; Gao, Y.; Gao, Y. S.; Garay Walls, F. M.; García, C.; García Navarro, J. E.; Garcia-Sciveres, M.; Gardner, R. W.; Garelli, N.; Garonne, V.; Gascon Bravo, A.; Gasnikova, K.; Gatti, C.; Gaudiello, A.; Gaudio, G.; Gauthier, L.; Gavrilenko, I. L.; Gay, C.; Gaycken, G.; Gazis, E. N.; Gecse, Z.; Gee, C. N. P.; Geich-Gimbel, Ch.; Geisen, M.; Geisler, M. P.; Gellerstedt, K.; Gemme, C.; Genest, M. H.; Geng, C.; Gentile, S.; Gentsos, C.; George, S.; Gerbaudo, D.; Gershon, A.; Ghasemi, S.; Ghneimat, M.; Giacobbe, B.; Giagu, S.; Giannetti, P.; Gibbard, B.; Gibson, S. M.; Gignac, M.; Gilchriese, M.; Gillam, T. P. S.; Gillberg, D.; Gilles, G.; Gingrich, D. M.; Giokaris, N.; Giordani, M. P.; Giorgi, F. M.; Giorgi, F. M.; Giraud, P. F.; Giromini, P.; Giugni, D.; Giuli, F.; Giuliani, C.; Giulini, M.; Gjelsten, B. K.; Gkaitatzis, S.; Gkialas, I.; Gkougkousis, E. L.; Gladilin, L. K.; Glasman, C.; Glatzer, J.; Glaysher, P. C. F.; Glazov, A.; Goblirsch-Kolb, M.; Godlewski, J.; Goldfarb, S.; Golling, T.; Golubkov, D.; Gomes, A.; Gonçalo, R.; Goncalves Pinto Firmino da Costa, J.; Gonella, G.; Gonella, L.; Gongadze, A.; González de La Hoz, S.; Gonzalez-Sevilla, S.; Goossens, L.; Gorbounov, P. A.; Gordon, H. A.; Gorelov, I.; Gorini, B.; Gorini, E.; Gorišek, A.; Gornicki, E.; Goshaw, A. T.; Gössling, C.; Gostkin, M. I.; Goudet, C. R.; Goujdami, D.; Goussiou, A. G.; Govender, N.; Gozani, E.; Graber, L.; Grabowska-Bold, I.; Gradin, P. O. J.; Grafström, P.; Gramling, J.; Gramstad, E.; Grancagnolo, S.; Gratchev, V.; Gravila, P. M.; Gray, H. M.; Graziani, E.; Greenwood, Z. D.; Grefe, C.; Gregersen, K.; Gregor, I. M.; Grenier, P.; Grevtsov, K.; Griffiths, J.; Grillo, A. A.; Grimm, K.; Grinstein, S.; Gris, Ph.; Grivaz, J.-F.; Groh, S.; Gross, E.; Grosse-Knetter, J.; Grossi, G. C.; Grout, Z. J.; Guan, L.; Guan, W.; Guenther, J.; Guescini, F.; Guest, D.; Gueta, O.; Gui, B.; Guido, E.; Guillemin, T.; Guindon, S.; Gul, U.; Gumpert, C.; Guo, J.; Guo, Y.; Gupta, R.; Gupta, S.; Gustavino, G.; Gutierrez, P.; Gutierrez Ortiz, N. G.; Gutschow, C.; Guyot, C.; Gwenlan, C.; Gwilliam, C. B.; Haas, A.; Haber, C.; Hadavand, H. K.; Haddad, N.; Hadef, A.; Hageböck, S.; Hagihara, M.; Hajduk, Z.; Hakobyan, H.; Haleem, M.; Haley, J.; Halladjian, G.; Hallewell, G. D.; Hamacher, K.; Hamal, P.; Hamano, K.; Hamilton, A.; Hamity, G. N.; Hamnett, P. G.; Han, L.; Hanagaki, K.; Hanawa, K.; Hance, M.; Haney, B.; Hanke, P.; Hanna, R.; Hansen, J. B.; Hansen, J. D.; Hansen, M. C.; Hansen, P. H.; Hara, K.; Hard, A. S.; Harenberg, T.; Hariri, F.; Harkusha, S.; Harrington, R. D.; Harrison, P. F.; Hartjes, F.; Hartmann, N. M.; Hasegawa, M.; Hasegawa, Y.; Hasib, A.; Hassani, S.; Haug, S.; Hauser, R.; Hauswald, L.; Havranek, M.; Hawkes, C. M.; Hawkings, R. J.; Hayakawa, D.; Hayden, D.; Hays, C. P.; Hays, J. M.; Hayward, H. S.; Haywood, S. J.; Head, S. J.; Heck, T.; Hedberg, V.; Heelan, L.; Heim, S.; Heim, T.; Heinemann, B.; Heinrich, J. J.; Heinrich, L.; Heinz, C.; Hejbal, J.; Helary, L.; Hellman, S.; Helsens, C.; Henderson, J.; Henderson, R. C. W.; Heng, Y.; Henkelmann, S.; Henriques Correia, A. M.; Henrot-Versille, S.; Herbert, G. H.; Herde, H.; Herget, V.; Hernández Jiménez, Y.; Herten, G.; Hertenberger, R.; Hervas, L.; Hesketh, G. G.; Hessey, N. P.; Hetherly, J. W.; Hickling, R.; Higón-Rodriguez, E.; Hill, E.; Hill, J. C.; Hiller, K. H.; Hillier, S. J.; Hinchliffe, I.; Hines, E.; Hinman, R. R.; Hirose, M.; Hirschbuehl, D.; Hobbs, J.; Hod, N.; Hodgkinson, M. C.; Hodgson, P.; Hoecker, A.; Hoeferkamp, M. R.; Hoenig, F.; Hohn, D.; Holmes, T. R.; Homann, M.; Honda, T.; Hong, T. M.; Hooberman, B. H.; Hopkins, W. H.; Horii, Y.; Horton, A. J.; Hostachy, J.-Y.; Hou, S.; Hoummada, A.; Howarth, J.; Hoya, J.; Hrabovsky, M.; Hristova, I.; Hrivnac, J.; Hryn'ova, T.; Hrynevich, A.; Hsu, C.; Hsu, P. J.; Hsu, S.-C.; Hu, Q.; Hu, S.; Huang, Y.; Hubacek, Z.; Hubaut, F.; Huegging, F.; Huffman, T. B.; Hughes, E. W.; Hughes, G.; Huhtinen, M.; Huo, P.; Huseynov, N.; Huston, J.; Huth, J.; Iacobucci, G.; Iakovidis, G.; Ibragimov, I.; Iconomidou-Fayard, L.; Ideal, E.; Idrissi, Z.; Iengo, P.; Igonkina, O.; Iizawa, T.; Ikegami, Y.; Ikeno, M.; Ilchenko, Y.; Iliadis, D.; Ilic, N.; Ince, T.; Introzzi, G.; Ioannou, P.; Iodice, M.; Iordanidou, K.; Ippolito, V.; Ishijima, N.; Ishino, M.; Ishitsuka, M.; Ishmukhametov, R.; Issever, C.; Istin, S.; Ito, F.; Iturbe Ponce, J. M.; Iuppa, R.; Iwanski, W.; Iwasaki, H.; Izen, J. M.; Izzo, V.; Jabbar, S.; Jackson, B.; Jackson, P.; Jain, V.; Jakobi, K. B.; Jakobs, K.; Jakobsen, S.; Jakoubek, T.; Jamin, D. O.; Jana, D. K.; Jansky, R.; Janssen, J.; Janus, M.; Jarlskog, G.; Javadov, N.; Javůrek, T.; Jeanneau, F.; Jeanty, L.; Jeng, G.-Y.; Jennens, D.; Jenni, P.; Jeske, C.; Jézéquel, S.; Ji, H.; Jia, J.; Jiang, H.; Jiang, Y.; Jiang, Z.; Jiggins, S.; Jimenez Pena, J.; Jin, S.; Jinaru, A.; Jinnouchi, O.; Jivan, H.; Johansson, P.; Johns, K. A.; Johnson, W. J.; Jon-And, K.; Jones, G.; Jones, R. W. L.; Jones, S.; Jones, T. J.; Jongmanns, J.; Jorge, P. M.; Jovicevic, J.; Ju, X.; Juste Rozas, A.; Köhler, M. K.; Kaczmarska, A.; Kado, M.; Kagan, H.; Kagan, M.; Kahn, S. J.; Kaji, T.; Kajomovitz, E.; Kalderon, C. W.; Kaluza, A.; Kama, S.; Kamenshchikov, A.; Kanaya, N.; Kaneti, S.; Kanjir, L.; Kantserov, V. A.; Kanzaki, J.; Kaplan, B.; Kaplan, L. S.; Kapliy, A.; Kar, D.; Karakostas, K.; Karamaoun, A.; Karastathis, N.; Kareem, M. J.; Karentzos, E.; Karnevskiy, M.; Karpov, S. N.; Karpova, Z. M.; Karthik, K.; Kartvelishvili, V.; Karyukhin, A. N.; Kasahara, K.; Kashif, L.; Kass, R. D.; Kastanas, A.; Kataoka, Y.; Kato, C.; Katre, A.; Katzy, J.; Kawade, K.; Kawagoe, K.; Kawamoto, T.; Kawamura, G.; Kazanin, V. F.; Keeler, R.; Kehoe, R.; Keller, J. S.; Kempster, J. J.; Keoshkerian, H.; Kepka, O.; Kerševan, B. P.; Kersten, S.; Keyes, R. A.; Khader, M.; Khalil-Zada, F.; Khanov, A.; Kharlamov, A. G.; Kharlamova, T.; Khoo, T. J.; Khovanskiy, V.; Khramov, E.; Khubua, J.; Kido, S.; Kilby, C. R.; Kim, H. Y.; Kim, S. H.; Kim, Y. K.; Kimura, N.; Kind, O. M.; King, B. T.; King, M.; Kirk, J.; Kiryunin, A. E.; Kishimoto, T.; Kisielewska, D.; Kiss, F.; Kiuchi, K.; Kivernyk, O.; Kladiva, E.; Klein, M. H.; Klein, M.; Klein, U.; Kleinknecht, K.; Klimek, P.; Klimentov, A.; Klingenberg, R.; Klinger, J. A.; Klioutchnikova, T.; Kluge, E.-E.; Kluit, P.; Kluth, S.; Knapik, J.; Kneringer, E.; Knoops, E. B. F. G.; Knue, A.; Kobayashi, A.; Kobayashi, D.; Kobayashi, T.; Kobel, M.; Kocian, M.; Kodys, P.; Koehler, N. M.; Koffas, T.; Koffeman, E.; Koi, T.; Kolanoski, H.; Kolb, M.; Koletsou, I.; Komar, A. A.; Komori, Y.; Kondo, T.; Kondrashova, N.; Köneke, K.; König, A. C.; Kono, T.; Konoplich, R.; Konstantinidis, N.; Kopeliansky, R.; Koperny, S.; Köpke, L.; Kopp, A. K.; Korcyl, K.; Kordas, K.; Korn, A.; Korol, A. A.; Korolkov, I.; Korolkova, E. V.; Kortner, O.; Kortner, S.; Kosek, T.; Kostyukhin, V. V.; Kotwal, A.; Koulouris, A.; Kourkoumeli-Charalampidi, A.; Kourkoumelis, C.; Kouskoura, V.; Kowalewska, A. B.; Kowalewski, R.; Kowalski, T. Z.; Kozakai, C.; Kozanecki, W.; Kozhin, A. S.; Kramarenko, V. A.; Kramberger, G.; Krasnopevtsev, D.; Krasny, M. W.; Krasznahorkay, A.; Kravchenko, A.; Kretz, M.; Kretzschmar, J.; Kreutzfeldt, K.; Krieger, P.; Krizka, K.; Kroeninger, K.; Kroha, H.; Kroll, J.; Kroseberg, J.; Krstic, J.; Kruchonak, U.; Krüger, H.; Krumnack, N.; Kruse, M. C.; Kruskal, M.; Kubota, T.; Kucuk, H.; Kuday, S.; Kuechler, J. T.; Kuehn, S.; Kugel, A.; Kuger, F.; Kuhl, A.; Kuhl, T.; Kukhtin, V.; Kukla, R.; Kulchitsky, Y.; Kuleshov, S.; Kuna, M.; Kunigo, T.; Kupco, A.; Kurashige, H.; Kurochkin, Y. A.; Kus, V.; Kuwertz, E. S.; Kuze, M.; Kvita, J.; Kwan, T.; Kyriazopoulos, D.; La Rosa, A.; La Rosa Navarro, J. L.; La Rotonda, L.; Lacasta, C.; Lacava, F.; Lacey, J.; Lacker, H.; Lacour, D.; Lacuesta, V. R.; Ladygin, E.; Lafaye, R.; Laforge, B.; Lagouri, T.; Lai, S.; Lammers, S.; Lampl, W.; Lançon, E.; Landgraf, U.; Landon, M. P. J.; Lanfermann, M. C.; Lang, V. S.; Lange, J. C.; Lankford, A. J.; Lanni, F.; Lantzsch, K.; Lanza, A.; Laplace, S.; Lapoire, C.; Laporte, J. F.; Lari, T.; Lasagni Manghi, F.; Lassnig, M.; Laurelli, P.; Lavrijsen, W.; Law, A. T.; Laycock, P.; Lazovich, T.; Lazzaroni, M.; Le, B.; Le Dortz, O.; Le Guirriec, E.; Le Quilleuc, E. P.; Leblanc, M.; Lecompte, T.; Ledroit-Guillon, F.; Lee, C. A.; Lee, S. C.; Lee, L.; Lefebvre, B.; Lefebvre, G.; Lefebvre, M.; Legger, F.; Leggett, C.; Lehan, A.; Lehmann Miotto, G.; Lei, X.; Leight, W. A.; Leister, A. G.; Leite, M. A. L.; Leitner, R.; Lellouch, D.; Lemmer, B.; Leney, K. J. C.; Lenz, T.; Lenzi, B.; Leone, R.; Leone, S.; Leonidopoulos, C.; Leontsinis, S.; Lerner, G.; Leroy, C.; Lesage, A. A. J.; Lester, C. G.; Levchenko, M.; Levêque, J.; Levin, D.; Levinson, L. J.; Levy, M.; Lewis, D.; Leyko, A. M.; Leyton, M.; Li, B.; Li, C.; Li, H.; Li, H. L.; Li, L.; Li, L.; Li, Q.; Li, S.; Li, X.; Li, Y.; Liang, Z.; Liberti, B.; Liblong, A.; Lichard, P.; Lie, K.; Liebal, J.; Liebig, W.; Limosani, A.; Lin, S. C.; Lin, T. H.; Lindquist, B. E.; Lionti, A. E.; Lipeles, E.; Lipniacka, A.; Lisovyi, M.; Liss, T. M.; Lister, A.; Litke, A. M.; Liu, B.; Liu, D.; Liu, H.; Liu, H.; Liu, J.; Liu, J. B.; Liu, K.; Liu, L.; Liu, M.; Liu, M.; Liu, Y. L.; Liu, Y.; Livan, M.; Lleres, A.; Llorente Merino, J.; Lloyd, S. L.; Lo Sterzo, F.; Lobodzinska, E. M.; Loch, P.; Loebinger, F. K.; Loew, K. M.; Loginov, A.; Lohse, T.; Lohwasser, K.; Lokajicek, M.; Long, B. A.; Long, J. D.; Long, R. E.; Longo, L.; Looper, K. A.; López, J. A.; Lopez Mateos, D.; Lopez Paredes, B.; Lopez Paz, I.; Lopez Solis, A.; Lorenz, J.; Lorenzo Martinez, N.; Losada, M.; Lösel, P. J.; Lou, X.; Lounis, A.; Love, J.; Love, P. A.; Lu, H.; Lu, N.; Lubatti, H. J.; Luci, C.; Lucotte, A.; Luedtke, C.; Luehring, F.; Lukas, W.; Luminari, L.; Lundberg, O.; Lund-Jensen, B.; Luzi, P. M.; Lynn, D.; Lysak, R.; Lytken, E.; Lyubushkin, V.; Ma, H.; Ma, L. L.; Ma, Y.; Maccarrone, G.; Macchiolo, A.; MacDonald, C. M.; Maček, B.; Machado Miguens, J.; Madaffari, D.; Madar, R.; Maddocks, H. J.; Mader, W. F.; Madsen, A.; Maeda, J.; Maeland, S.; Maeno, T.; Maevskiy, A.; Magradze, E.; Mahlstedt, J.; Maiani, C.; Maidantchik, C.; Maier, A. A.; Maier, T.; Maio, A.; Majewski, S.; Makida, Y.; Makovec, N.; Malaescu, B.; Malecki, Pa.; Maleev, V. P.; Malek, F.; Mallik, U.; Malon, D.; Malone, C.; Malone, C.; Maltezos, S.; Malyukov, S.; Mamuzic, J.; Mancini, G.; Mandelli, L.; Mandić, I.; Maneira, J.; Manhaes de Andrade Filho, L.; Manjarres Ramos, J.; Mann, A.; Manousos, A.; Mansoulie, B.; Mansour, J. D.; Mantifel, R.; Mantoani, M.; Manzoni, S.; Mapelli, L.; Marceca, G.; March, L.; Marchiori, G.; Marcisovsky, M.; Marjanovic, M.; Marley, D. E.; Marroquim, F.; Marsden, S. P.; Marshall, Z.; Marti-Garcia, S.; Martin, B.; Martin, T. A.; Martin, V. J.; Martin Dit Latour, B.; Martinez, M.; Martinez Outschoorn, V. I.; Martin-Haugh, S.; Martoiu, V. S.; Martyniuk, A. C.; Marzin, A.; Masetti, L.; Mashimo, T.; Mashinistov, R.; Masik, J.; Maslennikov, A. L.; Massa, I.; Massa, L.; Mastrandrea, P.; Mastroberardino, A.; Masubuchi, T.; Mättig, P.; Mattmann, J.; Maurer, J.; Maxfield, S. J.; Maximov, D. A.; Mazini, R.; Maznas, I.; Mazza, S. M.; Mc Fadden, N. C.; Mc Goldrick, G.; Mc Kee, S. P.; McCarn, A.; McCarthy, R. L.; McCarthy, T. G.; McClymont, L. I.; McDonald, E. F.; McFayden, J. A.; McHedlidze, G.; McMahon, S. J.; McPherson, R. A.; Medinnis, M.; Meehan, S.; Mehlhase, S.; Mehta, A.; Meier, K.; Meineck, C.; Meirose, B.; Melini, D.; Mellado Garcia, B. R.; Melo, M.; Meloni, F.; Meng, X.; Mengarelli, A.; Menke, S.; Meoni, E.; Mergelmeyer, S.; Mermod, P.; Merola, L.; Meroni, C.; Merritt, F. S.; Messina, A.; Metcalfe, J.; Mete, A. S.; Meyer, C.; Meyer, C.; Meyer, J.-P.; Meyer, J.; Meyer Zu Theenhausen, H.; Miano, F.; Middleton, R. P.; Miglioranzi, S.; Mijović, L.; Mikenberg, G.; Mikestikova, M.; Mikuž, M.; Milesi, M.; Milic, A.; Miller, D. W.; Mills, C.; Milov, A.; Milstead, D. A.; Minaenko, A. A.; Minami, Y.; Minashvili, I. A.; Mincer, A. I.; Mindur, B.; Mineev, M.; Minegishi, Y.; Ming, Y.; Mir, L. M.; Mistry, K. P.; Mitani, T.; Mitrevski, J.; Mitsou, V. A.; Miucci, A.; Miyagawa, P. S.; Mjörnmark, J. U.; Mlynarikova, M.; Moa, T.; Mochizuki, K.; Mohapatra, S.; Molander, S.; Moles-Valls, R.; Monden, R.; Mondragon, M. C.; Mönig, K.; Monk, J.; Monnier, E.; Montalbano, A.; Montejo Berlingen, J.; Monticelli, F.; Monzani, S.; Moore, R. W.; Morange, N.; Moreno, D.; Moreno Llácer, M.; Morettini, P.; Morgenstern, S.; Mori, D.; Mori, T.; Morii, M.; Morinaga, M.; Morisbak, V.; Moritz, S.; Morley, A. K.; Mornacchi, G.; Morris, J. D.; Mortensen, S. S.; Morvaj, L.; Mosidze, M.; Moss, J.; Motohashi, K.; Mount, R.; Mountricha, E.; Moyse, E. J. W.; Muanza, S.; Mudd, R. D.; Mueller, F.; Mueller, J.; Mueller, R. S. P.; Mueller, T.; Muenstermann, D.; Mullen, P.; Mullier, G. A.; Munoz Sanchez, F. J.; Murillo Quijada, J. A.; Murray, W. J.; Musheghyan, H.; Muškinja, M.; Myagkov, A. G.; Myska, M.; Nachman, B. P.; Nackenhorst, O.; Nagai, K.; Nagai, R.; Nagano, K.; Nagasaka, Y.; Nagata, K.; Nagel, M.; Nagy, E.; Nairz, A. M.; Nakahama, Y.; Nakamura, K.; Nakamura, T.; Nakano, I.; Naranjo Garcia, R. F.; Narayan, R.; Narrias Villar, D. I.; Naryshkin, I.; Naumann, T.; Navarro, G.; Nayyar, R.; Neal, H. A.; Nechaeva, P. Yu.; Neep, T. J.; Negri, A.; Negrini, M.; Nektarijevic, S.; Nellist, C.; Nelson, A.; Nemecek, S.; Nemethy, P.; Nepomuceno, A. A.; Nessi, M.; Neubauer, M. S.; Neumann, M.; Neves, R. M.; Nevski, P.; Newman, P. R.; Nguyen, D. H.; Nguyen Manh, T.; Nickerson, R. B.; Nicolaidou, R.; Nielsen, J.; Nikiforov, A.; Nikolaenko, V.; Nikolic-Audit, I.; Nikolopoulos, K.; Nilsen, J. K.; Nilsson, P.; Ninomiya, Y.; Nisati, A.; Nisius, R.; Nobe, T.; Nomachi, M.; Nomidis, I.; Nooney, T.; Norberg, S.; Nordberg, M.; Norjoharuddeen, N.; Novgorodova, O.; Nowak, S.; Nozaki, M.; Nozka, L.; Ntekas, K.; Nurse, E.; Nuti, F.; O'Grady, F.; O'Neil, D. C.; O'Rourke, A. A.; O'Shea, V.; Oakham, F. G.; Oberlack, H.; Obermann, T.; Ocariz, J.; Ochi, A.; Ochoa, I.; Ochoa-Ricoux, J. P.; Oda, S.; Odaka, S.; Ogren, H.; Oh, A.; Oh, S. H.; Ohm, C. C.; Ohman, H.; Oide, H.; Okawa, H.; Okumura, Y.; Okuyama, T.; Olariu, A.; Oleiro Seabra, L. F.; Olivares Pino, S. A.; Oliveira Damazio, D.; Olszewski, A.; Olszowska, J.; Onofre, A.; Onogi, K.; Onyisi, P. U. E.; Oreglia, M. J.; Oren, Y.; Orestano, D.; Orlando, N.; Orr, R. S.; Osculati, B.; Ospanov, R.; Otero Y Garzon, G.; Otono, H.; Ouchrif, M.; Ould-Saada, F.; Ouraou, A.; Oussoren, K. P.; Ouyang, Q.; Owen, M.; Owen, R. E.; Ozcan, V. E.; Ozturk, N.; Pachal, K.; Pacheco Pages, A.; Pacheco Rodriguez, L.; Padilla Aranda, C.; Pagáčová, M.; Pagan Griso, S.; Paganini, M.; Paige, F.; Pais, P.; Pajchel, K.; Palacino, G.; Palazzo, S.; Palestini, S.; Palka, M.; Pallin, D.; St. Panagiotopoulou, E.; Pandini, C. E.; Panduro Vazquez, J. G.; Pani, P.; Panitkin, S.; Pantea, D.; Paolozzi, L.; Papadopoulou, Th. D.; Papageorgiou, K.; Paramonov, A.; Paredes Hernandez, D.; Parker, A. J.; Parker, M. A.; Parker, K. A.; Parodi, F.; Parsons, J. A.; Parzefall, U.; Pascuzzi, V. R.; Pasqualucci, E.; Passaggio, S.; Pastore, Fr.; Pásztor, G.; Pataraia, S.; Pater, J. R.; Pauly, T.; Pearce, J.; Pearson, B.; Pedersen, L. E.; Pedersen, M.; Pedraza Lopez, S.; Pedro, R.; Peleganchuk, S. V.; Penc, O.; Peng, C.; Peng, H.; Penwell, J.; Peralva, B. S.; Perego, M. M.; Perepelitsa, D. V.; Perez Codina, E.; Perini, L.; Pernegger, H.; Perrella, S.; Peschke, R.; Peshekhonov, V. D.; Peters, K.; Peters, R. F. Y.; Petersen, B. A.; Petersen, T. C.; Petit, E.; Petridis, A.; Petridou, C.; Petroff, P.; Petrolo, E.; Petrov, M.; Petrucci, F.; Pettersson, N. E.; Peyaud, A.; Pezoa, R.; Phillips, P. W.; Piacquadio, G.; Pianori, E.; Picazio, A.; Piccaro, E.; Piccinini, M.; Pickering, M. A.; Piegaia, R.; Pilcher, J. E.; Pilkington, A. D.; Pin, A. W. J.; Pinamonti, M.; Pinfold, J. L.; Pingel, A.; Pires, S.; Pirumov, H.; Pitt, M.; Plazak, L.; Pleier, M.-A.; Pleskot, V.; Plotnikova, E.; Plucinski, P.; Pluth, D.; Poettgen, R.; Poggioli, L.; Pohl, D.; Polesello, G.; Poley, A.; Policicchio, A.; Polifka, R.; Polini, A.; Pollard, C. S.; Polychronakos, V.; Pommès, K.; Pontecorvo, L.; Pope, B. G.; Popeneciu, G. A.; Poppleton, A.; Pospisil, S.; Potamianos, K.; Potrap, I. N.; Potter, C. J.; Potter, C. T.; Poulard, G.; Poveda, J.; Pozdnyakov, V.; Pozo Astigarraga, M. E.; Pralavorio, P.; Pranko, A.; Prell, S.; Price, D.; Price, L. E.; Primavera, M.; Prince, S.; Prokofiev, K.; Prokoshin, F.; Protopopescu, S.; Proudfoot, J.; Przybycien, M.; Puddu, D.; Purohit, M.; Puzo, P.; Qian, J.; Qin, G.; Qin, Y.; Quadt, A.; Quayle, W. B.; Queitsch-Maitland, M.; Quilty, D.; Raddum, S.; Radeka, V.; Radescu, V.; Radhakrishnan, S. K.; Radloff, P.; Rados, P.; Ragusa, F.; Rahal, G.; Raine, J. A.; Rajagopalan, S.; Rammensee, M.; Rangel-Smith, C.; Ratti, M. G.; Rauch, D. M.; Rauscher, F.; Rave, S.; Ravenscroft, T.; Ravinovich, I.; Raymond, M.; Read, A. L.; Readioff, N. P.; Reale, M.; Rebuzzi, D. M.; Redelbach, A.; Redlinger, G.; Reece, R.; Reed, R. G.; Reeves, K.; Rehnisch, L.; Reichert, J.; Reiss, A.; Rembser, C.; Ren, H.; Rescigno, M.; Resconi, S.; Rezanova, O. L.; Reznicek, P.; Rezvani, R.; Richter, R.; Richter, S.; Richter-Was, E.; Ricken, O.; Ridel, M.; Rieck, P.; Riegel, C. J.; Rieger, J.; Rifki, O.; Rijssenbeek, M.; Rimoldi, A.; Rimoldi, M.; Rinaldi, L.; Ristić, B.; Ritsch, E.; Riu, I.; Rizatdinova, F.; Rizvi, E.; Rizzi, C.; Robertson, S. H.; Robichaud-Veronneau, A.; Robinson, D.; Robinson, J. E. M.; Robson, A.; Roda, C.; Rodina, Y.; Rodriguez Perez, A.; Rodriguez Rodriguez, D.; Roe, S.; Rogan, C. S.; Røhne, O.; Roloff, J.; Romaniouk, A.; Romano, M.; Romano Saez, S. M.; Romero Adam, E.; Rompotis, N.; Ronzani, M.; Roos, L.; Ros, E.; Rosati, S.; Rosbach, K.; Rose, P.; Rosien, N.-A.; Rossetti, V.; Rossi, E.; Rossi, L. P.; Rosten, J. H. N.; Rosten, R.; Rotaru, M.; Roth, I.; Rothberg, J.; Rousseau, D.; Rozanov, A.; Rozen, Y.; Ruan, X.; Rubbo, F.; Rudolph, M. S.; Rühr, F.; Ruiz-Martinez, A.; Rurikova, Z.; Rusakovich, N. A.; Ruschke, A.; Russell, H. L.; Rutherfoord, J. P.; Ruthmann, N.; Ryabov, Y. F.; Rybar, M.; Rybkin, G.; Ryu, S.; Ryzhov, A.; Rzehorz, G. F.; Saavedra, A. F.; Sabato, G.; Sacerdoti, S.; Sadrozinski, H. F.-W.; Sadykov, R.; Safai Tehrani, F.; Saha, P.; Sahinsoy, M.; Saimpert, M.; Saito, T.; Sakamoto, H.; Sakurai, Y.; Salamanna, G.; Salamon, A.; Salazar Loyola, J. E.; Salek, D.; Sales de Bruin, P. H.; Salihagic, D.; Salnikov, A.; Salt, J.; Salvatore, D.; Salvatore, F.; Salvucci, A.; Salzburger, A.; Sammel, D.; Sampsonidis, D.; Sánchez, J.; Sanchez Martinez, V.; Sanchez Pineda, A.; Sandaker, H.; Sandbach, R. L.; Sandhoff, M.; Sandoval, C.; Sankey, D. P. C.; Sannino, M.; Sansoni, A.; Santoni, C.; Santonico, R.; Santos, H.; Santoyo Castillo, I.; Sapp, K.; Sapronov, A.; Saraiva, J. G.; Sarrazin, B.; Sasaki, O.; Sato, K.; Sauvan, E.; Savage, G.; Savard, P.; Savic, N.; Sawyer, C.; Sawyer, L.; Saxon, J.; Sbarra, C.; Sbrizzi, A.; Scanlon, T.; Scannicchio, D. A.; Scarcella, M.; Scarfone, V.; Schaarschmidt, J.; Schacht, P.; Schachtner, B. M.; Schaefer, D.; Schaefer, L.; Schaefer, R.; Schaeffer, J.; Schaepe, S.; Schaetzel, S.; Schäfer, U.; Schaffer, A. C.; Schaile, D.; Schamberger, R. D.; Scharf, V.; Schegelsky, V. A.; Scheirich, D.; Schernau, M.; Schiavi, C.; Schier, S.; Schillo, C.; Schioppa, M.; Schlenker, S.; Schmidt-Sommerfeld, K. R.; Schmieden, K.; Schmitt, C.; Schmitt, S.; Schmitz, S.; Schneider, B.; Schnoor, U.; Schoeffel, L.; Schoening, A.; Schoenrock, B. D.; Schopf, E.; Schott, M.; Schouwenberg, J. F. P.; Schovancova, J.; Schramm, S.; Schreyer, M.; Schuh, N.; Schulte, A.; Schultens, M. J.; Schultz-Coulon, H.-C.; Schulz, H.; Schumacher, M.; Schumm, B. A.; Schune, Ph.; Schwartzman, A.; Schwarz, T. A.; Schweiger, H.; Schwemling, Ph.; Schwienhorst, R.; Schwindling, J.; Schwindt, T.; Sciolla, G.; Scuri, F.; Scutti, F.; Searcy, J.; Seema, P.; Seidel, S. C.; Seiden, A.; Seifert, F.; Seixas, J. M.; Sekhniaidze, G.; Sekhon, K.; Sekula, S. J.; Seliverstov, D. M.; Semprini-Cesari, N.; Serfon, C.; Serin, L.; Serkin, L.; Sessa, M.; Seuster, R.; Severini, H.; Sfiligoj, T.; Sforza, F.; Sfyrla, A.; Shabalina, E.; Shaikh, N. W.; Shan, L. Y.; Shang, R.; Shank, J. T.; Shapiro, M.; Shatalov, P. B.; Shaw, K.; Shaw, S. M.; Shcherbakova, A.; Shehu, C. Y.; Sherwood, P.; Shi, L.; Shimizu, S.; Shimmin, C. O.; Shimojima, M.; Shirabe, S.; Shiyakova, M.; Shmeleva, A.; Shoaleh Saadi, D.; Shochet, M. J.; Shojaii, S.; Shope, D. R.; Shrestha, S.; Shulga, E.; Shupe, M. A.; Sicho, P.; Sickles, A. M.; Sidebo, P. E.; Sideras Haddad, E.; Sidiropoulou, O.; Sidorov, D.; Sidoti, A.; Siegert, F.; Sijacki, Dj.; Silva, J.; Silverstein, S. B.; Simak, V.; Simic, Lj.; Simion, S.; Simioni, E.; Simmons, B.; Simon, D.; Simon, M.; Sinervo, P.; Sinev, N. B.; Sioli, M.; Siragusa, G.; Sivoklokov, S. Yu.; Sjölin, J.; Skinner, M. B.; Skottowe, H. P.; Skubic, P.; Slater, M.; Slavicek, T.; Slawinska, M.; Sliwa, K.; Slovak, R.; Smakhtin, V.; Smart, B. H.; Smestad, L.; Smiesko, J.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, M. N. K.; Smith, R. W.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snyder, I. M.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Soh, D. A.; Sokhrannyi, G.; Solans Sanchez, C. A.; Solar, M.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Son, H.; Song, H. Y.; Sood, A.; Sopczak, A.; Sopko, V.; Sorin, V.; Sosa, D.; Sotiropoulou, C. L.; Soualah, R.; Soukharev, A. M.; South, D.; Sowden, B. C.; Spagnolo, S.; Spalla, M.; Spangenberg, M.; Spannowsky, M.; Spanò, F.; Sperlich, D.; Spettel, F.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; St. Denis, R. D.; Stabile, A.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanek, R. W.; Stanescu, C.; Stanescu-Bellu, M.; Stanitzki, M. M.; Stapnes, S.; Starchenko, E. A.; Stark, G. H.; Stark, J.; Staroba, P.; Starovoitov, P.; Stärz, S.; Staszewski, R.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stewart, G. A.; Stillings, J. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strandlie, A.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Suchek, S.; Sugaya, Y.; Suk, M.; Sulin, V. V.; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Sundermann, J. E.; Suruliz, K.; Susinno, G.; Sutton, M. R.; Suzuki, S.; Svatos, M.; Swiatlowski, M.; Sykora, I.; Sykora, T.; Ta, D.; Taccini, C.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Taiblum, N.; Takai, H.; Takashima, R.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tan, K. G.; Tanaka, J.; Tanaka, M.; Tanaka, R.; Tanaka, S.; Tanioka, R.; Tannenwald, B. B.; Tapia Araya, S.; Tapprogge, S.; Tarem, S.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, A. C.; Taylor, G. N.; Taylor, P. T. E.; Taylor, W.; Teischinger, F. A.; Teixeira-Dias, P.; Temming, K. K.; Temple, D.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Theveneaux-Pelzer, T.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, P. D.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tipton, P.; Tisserant, S.; Todome, K.; Todorov, T.; Todorova-Nova, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, B.; Tornambe, P.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Trefzger, T.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Trofymov, A.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tseng, J. C.-L.; Tsiareshka, P. V.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsui, K. M.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tu, Y.; Tudorache, A.; Tudorache, V.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turecek, D.; Turgeman, D.; Turra, R.; Tuts, P. M.; Tyndel, M.; Ucchielli, G.; Ueda, I.; Ughetto, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usui, J.; Vacavant, L.; Vacek, V.; Vachon, B.; Valderanis, C.; Valdes Santurio, E.; Valencic, N.; Valentinetti, S.; Valero, A.; Valery, L.; Valkar, S.; Valls Ferrer, J. A.; van den Wollenberg, W.; van der Deijl, P. C.; van der Graaf, H.; van Eldik, N.; van Gemmeren, P.; van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vanguri, R.; Vaniachine, A.; Vankov, P.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vasquez, J. G.; Vasquez, G. A.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veeraraghavan, V.; Veloce, L. M.; Veloso, F.; Veneziano, S.; Ventura, A.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. A.; Viel, S.; Vigani, L.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Vykydal, Z.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, K.; Wang, R.; Wang, S. M.; Wang, T.; Wang, T.; Wang, W.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, S.; Weber, M. S.; Weber, S. W.; Weber, S. A.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, M. D.; Werner, P.; Wessels, M.; Wetter, J.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A.; White, M. J.; White, R.; Whiteson, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wittkowski, J.; Wolf, T. M. H.; Wolter, M. W.; Wolters, H.; Worm, S. D.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yildirim, E.; Yorita, K.; Yoshida, R.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J. M.; Yu, J.; Yuan, L.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanello, L.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, M.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, L.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; Zur Nedden, M.; Zwalinski, L.; Atlas Collaboration

2017-02-01

The W boson angular distribution in events with high transverse momentum jets is measured using data collected by the ATLAS experiment from proton-proton collisions at a centre-of-mass energy √{ s} = 8 TeV at the Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb-1. The focus is on the contributions to W +jets processes from real W emission, which is achieved by studying events where a muon is observed close to a high transverse momentum jet. At small angular separations, these contributions are expected to be large. Various theoretical models of this process are compared to the data in terms of the absolute cross-section and the angular distributions of the muon from the leptonic W decay.

Nonreciprocal Transverse Photonic Spin and Magnetization-Induced Electromagnetic Spin-Orbit Coupling

PubMed Central

Levy, Miguel; Karki, Dolendra

2017-01-01

We present a formulation of electromagnetic spin-orbit coupling in magneto-optic media, and propose an alternative source of spin-orbit coupling to non-paraxial optics vortices. Our treatment puts forth a formulation of nonreciprocal transverse-spin angular-momentum-density shifts for evanescent waves in magneto-optic waveguide media. It shows that magnetization-induced electromagnetic spin-orbit coupling is possible, and that it leads to unequal spin to orbital angular momentum conversion in magneto-optic media evanescent waves in opposite propagation-directions. Generation of free-space helicoidal beams based on this conversion is shown to be spin-helicity- and magnetization-dependent. We show that transverse-spin to orbital angular momentum coupling into magneto-optic waveguide media engenders spin-helicity-dependent unidirectional propagation. This unidirectional effect produces different orbital angular momenta in opposite directions upon excitation-spin-helicity reversals. PMID:28059120

Post-Newtonian templates for binary black-hole inspirals: the effect of the horizon fluxes and the secular change in the black-hole masses and spins

NASA Astrophysics Data System (ADS)

Isoyama, Soichiro; Nakano, Hiroyuki

2018-01-01

Black holes (BHs) in an inspiraling compact binary system absorb the gravitational-wave (GW) energy and angular-momentum fluxes across their event horizons and this leads to the secular change in their masses and spins during the inspiral phase. The goal of this paper is to present ready-to-use, 3.5 post-Newtonian (PN) template families for spinning, non-precessing, binary BH inspirals in quasicircular orbits, including the 2.5 PN and 3.5 PN horizon-flux contributions as well as the correction due to the secular change in the BH masses and spins through 3.5 PN order, respectively, in phase. We show that, for binary BHs observable by Advanced LIGO with high mass ratios (larger than  ∼10) and large aligned-spins (larger than  ∼ 0.7 ), the mismatch between the frequency-domain template with and without the horizon-flux contribution is typically above the 3% mark. For (supermassive) binary BHs observed by LISA, even a moderate mass-ratios and spins can produce a similar level of the mismatch. Meanwhile, the mismatch due to the secular time variations of the BH masses and spins is well below the 1% mark in both cases, hence this is truly negligible. We also point out that neglecting the cubic-in-spin, point-particle phase term at 3.5 PN order would deteriorate the effect of BH absorption in the template.

DEEP, LOW-MASS RATIO OVERCONTACT BINARY SYSTEMS. XII. CK BOOTIS WITH POSSIBLE CYCLIC MAGNETIC ACTIVITY AND ADDITIONAL COMPANION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Y.-G.; Qian, S.-B.; Soonthornthum, B., E-mail: yygcn@163.com, E-mail: qsb@ynao.ac.cn

2012-05-15

We present precision CCD photometry, a period study, and a two-color simultaneous Wilson code solution of the short-period contact binary CK Bootis. The asymmetric light curves were modeled by a dark spot on the primary component. The result identifies that CK Boo is an A-type W UMa binary with a high fillout of f = 71.7({+-} 4.4)%. From the O - C curve, it is found that the orbital period changes in a complicated mode, i.e., a long-term increase with two sinusoidal variations. One cyclic oscillation with a period of 10.67({+-} 0.20) yr may result from magnetic activity cycles, whichmore » are identified by the variability of Max. I - Max. II. Another sinusoidal variation (i.e., A = 0.0131 days({+-} 0.0009 days) and P{sub 3} = 24.16({+-} 0.64) yr) may be attributed to the light-time effect due to a third body. This kind of additional companion can extract angular momentum from the central binary system. The orbital period secularly increases at a rate of dP/dt = +9.79 ({+-}0.80) Multiplication-Sign 10{sup -8} days yr{sup -1}, which may be interpreted by conservative mass transfer from the secondary to the primary. This kind of deep, low-mass ratio overcontact binaries may evolve into a rapid-rotating single star, only if the contact configuration do not break down at J{sub spin} > (1/3)J{sub orb}.« less

Magnetic braking in Solar-type close binaries

NASA Astrophysics Data System (ADS)

Maceroni, C.; Rucinski, S. M.

In tidally locked binaries the angular momentum loss by magnetic braking affects the orbital period. While this effect is too small to be detected in individual systems, its signature can be seen in shape of the orbital period distribution of suitable samples. As a consequence information on the braking mechanisms can be obtained - at least in principle - from the analysis of the distributions, the main problems being the selection of a large and homogeneous sample of binaries and the appropriate treatment of the observational biases. New large databases of variable stars are becoming available as by-products of microlensing projects, which have the advantage of joining, for the first time, sample richness and homogeneity. We report the main results of the analysis of the eclipsing binaries in OGLE-I catalog, that contains several thousands variables detected in a pencil-beam search volume towards the Baade's Window. By means of an automatic filtering algorithm we extracted a sample of 74 detached, equal-mass, main-sequence binary stars with short orbital periods (i.e., in the range 0.19 < P < 8 days) and derived from the presently observed period distribution, after correction for selection effects, the expected slope of the braking law. The results suggest an AML braking law very close to the "saturated" one, with a very weak dependence on the period. However we are still far from constraining the precise value of the slope, because of the important role played by the observational bias.

Relaxation near Supermassive Black Holes Driven by Nuclear Spiral Arms: Anisotropic Hypervelocity Stars, S-stars, and Tidal Disruption Events

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamers, Adrian S.; Perets, Hagai B., E-mail: hamers@ias.edu

Nuclear spiral arms are small-scale transient spiral structures found in the centers of galaxies. Similarly to their galactic-scale counterparts, nuclear spiral arms can perturb the orbits of stars. In the case of the Galactic center (GC), these perturbations can affect the orbits of stars and binaries in a region extending to several hundred parsecs around the supermassive black hole (SMBH), causing diffusion in orbital energy and angular momentum. This diffusion process can drive stars and binaries to close approaches with the SMBH, disrupting single stars in tidal disruption events (TDEs), or disrupting binaries, leaving a star tightly bound to themore » SMBH and an unbound star escaping the galaxy, i.e., a hypervelocity star (HVS). Here, we consider diffusion by nuclear spiral arms in galactic nuclei, specifically the Milky Way GC. We determine nuclear-spiral-arm-driven diffusion rates using test-particle integrations and compute disruption rates. Our TDE rates are up to 20% higher compared to relaxation by single stars. For binaries, the enhancement is up to a factor of ∼100, and our rates are comparable to the observed numbers of HVSs and S-stars. Our scenario is complementary to relaxation driven by massive perturbers. In addition, our rates depend on the inclination of the binary with respect to the Galactic plane. Therefore, our scenario provides a novel potential source for the observed anisotropic distribution of HVSs. Nuclear spiral arms may also be important for accelerating the coalescence of binary SMBHs and for supplying nuclear star clusters with stars and gas.« less

CENTRIFUGE END CAP

DOEpatents

Beams, J.W.; Snoddy, L.B.

1960-08-01

An end cap for ultra-gas centrifuges is designed to impart or remove angular momentum to or from the gas and to bring the entering gas to the temperature of the gas inside the centrifuge. The end cap is provided with slots or fins for adjusting the temperature and the angular momentum of the entering gas to the temperature and momentum of the gas in the centrifuge and is constructed to introduce both the inner and the peripheral stream into the centrifuge.

Observation of plasma toroidal-momentum dissipation by neoclassical toroidal viscosity.

PubMed

Zhu, W; Sabbagh, S A; Bell, R E; Bialek, J M; Bell, M G; LeBlanc, B P; Kaye, S M; Levinton, F M; Menard, J E; Shaing, K C; Sontag, A C; Yuh, H

2006-06-09

Dissipation of plasma toroidal angular momentum is observed in the National Spherical Torus Experiment due to applied nonaxisymmetric magnetic fields and their plasma-induced increase by resonant field amplification and resistive wall mode destabilization. The measured decrease of the plasma toroidal angular momentum profile is compared to calculations of nonresonant drag torque based on the theory of neoclassical toroidal viscosity. Quantitative agreement between experiment and theory is found when the effect of toroidally trapped particles is included.

Effect of a magnetic field on molecule-solvent angular momentum transfer

NASA Astrophysics Data System (ADS)

Rzadkowski, Wojciech; Lemeshko, Mikhail

2018-03-01

Recently it was shown that a molecule rotating in a quantum solvent can be described in terms of the "angulon" quasiparticle [M. Lemeshko, Phys. Rev. Lett. 118, 095301 (2017)]. Here we extend the angulon theory to the case of molecules possessing an additional spin-1/2 degree of freedom and study the behavior of the system in the presence of a static magnetic field. We show that exchange of angular momentum between the molecule and the solvent can be altered by the field, even though the solvent itself is non-magnetic. In particular, we demonstrate a possibility to control resonant emission of phonons with a given angular momentum using a magnetic field.

Influence of the photon orbital angular momentum on electric dipole transitions: negative experimental evidence.

PubMed

Giammanco, F; Perona, A; Marsili, P; Conti, F; Fidecaro, F; Gozzini, S; Lucchesini, A

2017-01-15

We describe an experiment of atomic spectroscopy devoted to ascertaining whether the orbital angular momentum (OAM) of photons has the same property of interacting with atoms or molecules as occurs for the spin angular momentum (SAM). In our experiment, rubidium vapors are excited by means of laser radiation with different combinations of OAM and SAM, particularly selected to inhibit or enhance the fluorescence according to the selection rules for the electric dipole transitions between the fundamental state and the first excited doublet. Our results clearly show that an electric-dipole-type transition is insensitive to the OAM value, and provide an original validation of a problem long debated in theoretical works.

Canonical angular momentum compression near the Brillouin limit

NASA Astrophysics Data System (ADS)

Jeong, E.; Gilson, E.; Fajans, J.

2000-10-01

Near the Brillouin limit, the angular momentum of a trapped, T=0, pure-electron plasma approaches zero. If the plasma expands axially, its density would appear to drop. However, the plasma's canonical angular momentum is not changed by an axial expansion, so the plasma must stay near the Brillouin limit; thus the plasma's density cannot change when it is expanded. The only way for the plasma density to remain constant as the plasma length increases is for the plasma radius to decrease. Dynamically, this decrease is caused by the polarization drift induced by a small decrease in the density. In this poster we present preliminary experimental evidence demonstrating this radial compression. This work was supported by the ONR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, J.

Relative and absolute populations of 19 levels in beam-foil--excited neutral helium at 0.275 MeV have been measured. The singlet angular-momentum sequences show dependences on principal quantum number consistent with n$sup -3$, but the triplet sequences do not. Singlet and triplet angular-momentum sequences show similar dependences on level excitation energy. Excitation functions for six representative levels were measured in the range 0.160 to 0.500 MeV. The absolute level populations increase with energy, whereas the neutral fraction of the beam decreases with energy. Further, the P angular-momentum levels are found to be overpopulated with respect to the S and D levels. Themore » overpopulation decreases with increasing principal quantum number.« less

Attitude motion of a non-attitude-controlled cylindrical satellite

NASA Technical Reports Server (NTRS)

Wilkinson, C. K.

1988-01-01

In 1985, two non-attitude-controlled satellites were each placed in a low earth orbit by the Scout Launch Vehicle. The satellites were cylindrical in shape and contained reservoirs of hydrazine fuel. Three-axis magnetometer measurements, telemetered in real time, were used to derive the attitude motion of each satellite. Algorithms are generated to deduce possible orientations (and magnitudes) of each vehicle's angular momentum for each telemetry contact. To resolve ambiguities at each contact, a force model was derived to simulate the significant long-term effects of magnetic, gravity gradient, and aerodynamic torques on the angular momentum of the vehicles. The histories of the orientation and magnitude of the angular momentum are illustrated.

Gimbal-Angle Vectors of the Nonredundant CMG Cluster

NASA Astrophysics Data System (ADS)

Lee, Donghun; Bang, Hyochoong

2018-05-01

This paper deals with the method using the preferred gimbal angles of a control moment gyro (CMG) cluster for controlling spacecraft attitude. To apply the method to the nonredundant CMG cluster, analytical gimbal-angle solutions for the zero angular momentum state are derived, and the gimbal-angle vectors for the nonzero angular momentum states are studied by a numerical method. It will be shown that the number of the gimbal-angle vectors is determined from the given skew angle and the angular momentum state of the CMG cluster. Through numerical examples, it is shown that the method using the preferred gimbal-angle is an efficient approach to avoid internal singularities for the nonredundant CMG cluster.

The photon gas formulation of thermal radiation

NASA Technical Reports Server (NTRS)

Ried, R. C., Jr.

1975-01-01

A statistical consideration of the energy, the linear momentum, and the angular momentum of the photons that make up a thermal radiation field was presented. A general nonequilibrium statistical thermodynamics approach toward a macroscopic description of thermal radiation transport was developed and then applied to the restricted equilibrium statistical thermostatics derivation of the energy, linear momentum, and intrinsic angular momentum equations for an isotropic photon gas. A brief treatment of a nonisotropic photon gas, as an example of the results produced by the nonequilibrium statistical thermodynamics approach, was given. The relativistic variation of temperature and the invariance of entropy were illustrated.

Variations in atmospheric angular momentum and the length of day

NASA Technical Reports Server (NTRS)

Rosen, R. D.; Salstein, D. A.

1982-01-01

Six years of twice daily global analyses were used to create and study a lengthy time series of high temporal resolution angular momentum values. Changes in these atmospheric values were compared to independently determined charges in the rotation rate of the solid Earth. Finally, the atmospheric data was examined in more detail to determine the time and space scales on which variations in momentum occur within the atmosphere and which regions are contributing most to the changes found in the global integral. The data and techniques used to derive the time series of momentum values are described.

A Spectroscopic and Mineralogical Study of Multiple Asteroid Systems

NASA Astrophysics Data System (ADS)

Lindsay, Sean S.; Emery, J. P.; Marchis, F.; Enriquez, J.; Assafin, M.

2013-10-01

There are currently ~200 identified multiple asteroid systems (MASs). These systems display a large diversity in heliocentric distance, size/mass ratio, system angular momentum, mutual orbital parameters, and taxonomic class. These characteristics are simplified under the nomenclature of Descamps and Marchis (2008), which divides MASs into four types: Type-1 - large asteroids with small satellites; Type-2 - similar size double asteroids; Type-3 - small asynchronous systems; and Type-4 - contact-binary asteroids. The large MAS diversity suggests multiple formation mechanisms are required to understand their origins. There are currently three broad formation scenarios: 1) ejecta from impacts; 2) catastrophic disruption followed by rotational fission; and 3) tidal disruption. The taxonomic class and mineralogy of the MASs coupled with the average density and system angular momentum provide a potential means to discriminate between proposed formation mechanisms. We present visible and near-infrared (NIR) spectra spanning 0.45 - 2.45 μm for 23 Main Belt MASs. The data were primarily obtained using the Southern Astrophysical Research Telescope (SOAR) Goodman High Throughput Spectrograph (August 2011 - July 2012) for the visible data and the InfraRed Telescope Facility (IRTF) SpeX Spectrograph (August 2008 - May 2013) for the IR data. Our data were supplemented using previously published data when necessary. The asteroids' Bus-DeMeo taxonomic classes are determined using the MIT SMASS online classification routines. Our sample includes 3 C-types, 1 X-type, 1 K-type, 1 L-type, 4 V-types, 10 S-types, 2 Sq- or Q-types, and 1 ambiguous classification. We calculate the 1- and 2-μm band centers, depths, and areas to determine the pyroxene mineralogy (molar Fs and Wo) of the surfaces using empirically derived equations. The NIR band analysis allows us to determine the S-type subclasses, S(I) - S(VII), which roughly tracks olivine-pyroxene chemistry. A comparison of the orbital parameters, physical parameters (size, density, and angular momentum), collisional family membership, and taxonomy is presented in an effort to find correlations, which may give insights to how these MASs formation mechanisms.

Spin-Orbit Coupling and the Conservation of Angular Momentum

ERIC Educational Resources Information Center

Hnizdo, V.

2012-01-01

In nonrelativistic quantum mechanics, the total (i.e. orbital plus spin) angular momentum of a charged particle with spin that moves in a Coulomb plus spin-orbit-coupling potential is conserved. In a classical nonrelativistic treatment of this problem, in which the Lagrange equations determine the orbital motion and the Thomas equation yields the…

Inclusion of angular momentum in FREYA

DOE PAGES

Randrup, Jørgen; Vogt, Ramona

2015-05-18

The event-by-event fission model FREYA generates large samples of complete fission events from which any observable can extracted, including fluctuations of the observables and the correlations between them. We describe here how FREYA was recently refined to include angular momentum throughout. Subsequently we present some recent results for both neutron and photon observables.

Obtaining the Electron Angular Momentum Coupling Spectroscopic Terms, jj

ERIC Educational Resources Information Center

Orofino, Hugo; Faria, Roberto B.

2010-01-01

A systematic procedure is developed to obtain the electron angular momentum coupling (jj) spectroscopic terms, which is based on building microstates in which each individual electron is placed in a different m[subscript j] "orbital". This approach is similar to that used to obtain the spectroscopic terms under the Russell-Saunders (LS) coupling…

Singularities in Dromo formulation. Analysis of deep flybys

NASA Astrophysics Data System (ADS)

Roa, Javier; Sanjurjo-Rivo, Manuel; Peláez, Jesús

2015-08-01

The singularities in Dromo are characterized in this paper, both from an analytical and a numerical perspective. When the angular momentum vanishes, Dromo may encounter a singularity in the evolution equations. The cancellation of the angular momentum occurs in very specific situations and may be caused by the action of strong perturbations. The gravitational attraction of a perturbing planet may lead to rapid changes in the angular momentum of the particle. In practice, this situation may be encountered during deep planetocentric flybys. The performance of Dromo is evaluated in different scenarios. First, Dromo is validated for integrating the orbit of Near Earth Asteroids. Resulting errors are of the order of the diameter of the asteroid. Second, a set of theoretical flybys are designed for analyzing the performance of the formulation in the vicinity of the singularity. New sets of Dromo variables are proposed in order to minimize the dependency of Dromo on the angular momentum. A slower time scale is introduced, leading to a more stable description of the flyby phase. Improvements in the overall performance of the algorithm are observed when integrating orbits close to the singularity.

Gravity-Assist Mechanical Simulator for Outreach

NASA Technical Reports Server (NTRS)

Doody, David F.; White, Victor E.; Schaff, Mitch D.

2012-01-01

There is no convenient way to demonstrate mechanically, as an outreach (or inreach) topic, the angular momentum trade-offs and the conservation of angular momentum associated with gravityassist interplanetary trajectories. The mechanical concepts that underlie gravity assist are often misunderstood or confused, possibly because there is no mechanical analog to it in everyday experience. The Gravity Assist Mech - anical Simulator is a hands-on solution to this longstanding technical communications challenge. Users intuitively grasp the concepts, meeting specific educational objectives. A manually spun wheel with high angular mass and low-friction bearings supplies momentum to an attached spherical neodymium magnet that represents a planet orbiting the Sun. A steel bearing ball following a trajectory across a glass plate above the wheel and magnet undergoes an elastic collision with the revolving magnet, illustrating the gravitational elastic collision between spacecraft and planet on a gravity-assist interplanetary trajectory. Manually supplying the angular momentum for the elastic collision, rather than observing an animation, intuitively conveys the concepts, meeting nine specific educational objectives. Many NASA and JPL interplanetary missions are enabled by the gravity-assist technique.

Particle dynamics around time conformal regular black holes via Noether symmetries

NASA Astrophysics Data System (ADS)

Jawad, Abdul; Umair Shahzad, M.

The time conformal regular black hole (RBH) solutions which are admitting the time conformal factor e𝜖g(t), where g(t) is an arbitrary function of time and 𝜖 is the perturbation parameter are being considered. The approximate Noether symmetries technique is being used for finding the function g(t) which leads to t α. The dynamics of particles around RBHs are also being discussed through symmetry generators which provide approximate energy as well as angular momentum of the particles. In addition, we analyze the motion of neutral and charged particles around two well known RBHs such as charged RBH using Fermi-Dirac distribution and Kehagias-Sftesos asymptotically flat RBH. We obtain the innermost stable circular orbit and corresponding approximate energy and angular momentum. The behavior of effective potential, effective force and escape velocity of the particles in the presence/absence of magnetic field for different values of angular momentum near horizons are also being analyzed. The stable and unstable regions of particle near horizons due to the effect of angular momentum and magnetic field are also explained.

Encoding photonic angular momentum information onto surface plasmon polaritons with plasmonic lens.

PubMed

Liu, Aiping; Rui, Guanghao; Ren, Xifeng; Zhan, Qiwen; Guo, Guangcan; Guo, Guoping

2012-10-22

Both spin angular momentum (SAM) and orbital angular momentum (OAM) can be used to carry information in classical optics and quantum optics. In this paper, the encoding of angular momentum (AM) information of photons onto surface plasmon polaritons (SPPs) is demonstrated using a nano-ring plasmonic lens. Near-field energy distribution on the metal surface is measured using a near-field scanning optical microscope (NSOM) when the plasmonic lens is excited by photons with different combinations of SAM and OAM. It is found that both the SAM and OAM can influence the near field energy distribution of SPPs. More interestingly, numerical and experimental studies reveal that the energy distribution on the plasmonic lens surface is determined by the absolute value of the total AM. This gives direct evidences that SPPs can be encoded with the photonic SAM and OAM information simultaneously and the spin degeneracy of the photons can be removed using the interactions between photonic OAM and plasmonic lens. The findings are useful not only for the fundamental understanding of the photonic AM but also for the future design of plasmonic quantum optics devices and systems.

Effect of angular momentum alignment and strong magnetic fields on the formation of protostellar discs

NASA Astrophysics Data System (ADS)

Gray, William J.; McKee, Christopher F.; Klein, Richard I.

2018-01-01

Star-forming molecular clouds are observed to be both highly magnetized and turbulent. Consequently, the formation of protostellar discs is largely dependent on the complex interaction between gravity, magnetic fields, and turbulence. Studies of non-turbulent protostellar disc formation with realistic magnetic fields have shown that these fields are efficient in removing angular momentum from the forming discs, preventing their formation. However, once turbulence is included, discs can form in even highly magnetized clouds, although the precise mechanism remains uncertain. Here, we present several high-resolution simulations of turbulent, realistically magnetized, high-mass molecular clouds with both aligned and random turbulence to study the role that turbulence, misalignment, and magnetic fields have on the formation of protostellar discs. We find that when the turbulence is artificially aligned so that the angular momentum is parallel to the initial uniform field, no rotationally supported discs are formed, regardless of the initial turbulent energy. We conclude that turbulence and the associated misalignment between the angular momentum and the magnetic field are crucial in the formation of protostellar discs in the presence of realistic magnetic fields.

Three close binaries in different evolutionary stages in the old open cluster NGC 188

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, L. Y.; Qian, S. B.; Liu, L.

2014-02-01

NGC 188 is a good laboratory for studying the formation and evolution of W UMa type contact binaries due to its rich populations of them. We present a detailed photometric study of three short-period close binaries, EP Cep, ES Cep, and V369 Cep, in the old open cluster NGC 188 based on our two-set photometric observations. We discovered that both EP Cep and ES Cep are shallow-contact binaries with continuously decreasing periods. The difference is in their mass ratios. EP Cep has an extremely low-mass ratio, q = 0.15, while ES Cep has a relatively high-mass ratio, q = 0.69,more » indicating that they lie in different evolutionary stages. ES Cep is likely a newly formed contact binary via a Case A mass transfer, while EP Cep is an evolved system and may be on the oscillations caused by the combined effect of the thermal relaxation oscillation and the variable angular momentum loss. For another system, V369 Cep, we found that it is a primary-filling near-contact binary. Both the semidetached configuration and the continuous decrease in the orbital period indicate that it is undergoing a mass transfer from the primary component to the secondary one. This conclusion is in agreement with the excess luminosity seen in the light curves on the ingress of the secondary minimum produced by the impact of the mass transfer. All of the results suggest that V369 Cep is evolving into contact, and a shallow-contact high-mass ratio system similar to ES Cep will be formed. Then, it will evolve into a low-mass ratio contact binary just like EP Cep, and finally merge into a rapidly rotating single star.« less

Angular structure of jet quenching within a hybrid strong/weak coupling model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casalderrey-Solana, Jorge; Gulhan, Doga Can; Milhano, José Guilherme

Within the context of a hybrid strong/weak coupling model of jet quenching, we study the modification of the angular distribution of the energy within jets in heavy ion collisions, as partons within jet showers lose energy and get kicked as they traverse the strongly coupled plasma produced in the collision. To describe the dynamics transverse to the jet axis, we add the effects of transverse momentum broadening into our hybrid construction, introducing a parameter K≡qˆ/T3K≡q^/T3 that governs its magnitude. We show that, because of the quenching of the energy of partons within a jet, even when K ≠ 0 themore » jets that survive with some specified energy in the final state are narrower than jets with that energy in proton-proton collisions. For this reason, many standard observables are rather insensitive to K. We also propose a new differential jet shape ratio observable in which the effects of transverse momentum broadening are apparent. We also analyze the response of the medium to the passage of the jet through it, noting that the momentum lost by the jet appears as the momentum of a wake in the medium. After freezeout this wake becomes soft particles with a broad angular distribution but with net momentum in the jet direction, meaning that the wake contributes to what is reconstructed as a jet. Thus, this effect must be included in any description of the angular structure of the soft component of a jet. We show that the particles coming from the response of the medium to the momentum and energy deposited in it leads to a correlation between the momentum of soft particles well separated from the jet in angle with the direction of the jet momentum, and find qualitative but not quantitative agreement with experimental data on observables designed to extract such a correlation. Generally, by confronting the results that we obtain upon introducing transverse momentum broadening and the response of the medium to the jet with available jet data, we highlight the importance of these processes for understanding the internal, soft, angular structure of high energy jets.« less

Angular structure of jet quenching within a hybrid strong/weak coupling model

DOE PAGES

Casalderrey-Solana, Jorge; Gulhan, Doga Can; Milhano, José Guilherme; ...

2017-03-27

Within the context of a hybrid strong/weak coupling model of jet quenching, we study the modification of the angular distribution of the energy within jets in heavy ion collisions, as partons within jet showers lose energy and get kicked as they traverse the strongly coupled plasma produced in the collision. To describe the dynamics transverse to the jet axis, we add the effects of transverse momentum broadening into our hybrid construction, introducing a parameter K≡qˆ/T3K≡q^/T3 that governs its magnitude. We show that, because of the quenching of the energy of partons within a jet, even when K ≠ 0 themore » jets that survive with some specified energy in the final state are narrower than jets with that energy in proton-proton collisions. For this reason, many standard observables are rather insensitive to K. We also propose a new differential jet shape ratio observable in which the effects of transverse momentum broadening are apparent. We also analyze the response of the medium to the passage of the jet through it, noting that the momentum lost by the jet appears as the momentum of a wake in the medium. After freezeout this wake becomes soft particles with a broad angular distribution but with net momentum in the jet direction, meaning that the wake contributes to what is reconstructed as a jet. Thus, this effect must be included in any description of the angular structure of the soft component of a jet. We show that the particles coming from the response of the medium to the momentum and energy deposited in it leads to a correlation between the momentum of soft particles well separated from the jet in angle with the direction of the jet momentum, and find qualitative but not quantitative agreement with experimental data on observables designed to extract such a correlation. Generally, by confronting the results that we obtain upon introducing transverse momentum broadening and the response of the medium to the jet with available jet data, we highlight the importance of these processes for understanding the internal, soft, angular structure of high energy jets.« less

The angular momentum of cosmological coronae and the inside-out growth of spiral galaxies

NASA Astrophysics Data System (ADS)

Pezzulli, Gabriele; Fraternali, Filippo; Binney, James

2017-05-01

Massive and diffuse haloes of hot gas (coronae) are important intermediaries between cosmology and galaxy evolution, storing mass and angular momentum acquired from the cosmic web until eventual accretion on to star-forming discs. We introduce a method to reconstruct the rotation of a galactic corona, based on its angular momentum distribution (AMD). This allows us to investigate in what conditions the angular momentum acquired from tidal torques can be transferred to star-forming discs and explain observed galaxy-scale processes, such as inside-out growth and the build-up of abundance gradients. We find that a simple model of an isothermal corona with a temperature slightly smaller than virial and a cosmologically motivated AMD is in good agreement with galaxy evolution requirements, supporting hot-mode accretion as a viable driver for the evolution of spiral galaxies in a cosmological context. We predict moderately sub-centrifugal rotation close to the disc and slow rotation close to the virial radius. Motivated by the observation that the Milky Way has a relatively hot corona (T ≃ 2 × 106 K), we also explore models with a temperature larger than virial. To be able to drive inside-out growth, these models must be significantly affected by feedback, either mechanical (ejection of low angular momentum material) or thermal (heating of the central regions). However, the agreement with galaxy evolution constraints becomes, in these cases, only marginal, suggesting that our first and simpler model may apply to a larger fraction of galaxy evolution history.

Protoplanetary disc response to distant tidal encounters in stellar clusters

NASA Astrophysics Data System (ADS)

Winter, A. J.; Clarke, C. J.; Rosotti, G.; Booth, R. A.

2018-04-01

The majority of stars form in a clustered environment. This has an impact on the evolution of surrounding protoplanetary discs (PPDs) due to either photoevaporation or tidal truncation. Consequently, the development of planets depends on formation environment. Here, we present the first thorough investigation of tidally induced angular momentum loss in PPDs in the distant regime, partly motivated by claims in the literature for the importance of distant encounters in disc evolution. We employ both theoretical predictions and dynamical/hydrodynamical simulations in 2D and 3D. Our theoretical analysis is based on that of Ostriker (1994) and leads us to conclude that in the limit that the closest approach distance xmin ≫ r, the radius of a particle ring, the fractional change in angular momentum scales as (xmin/r)-5. This asymptotic limit ensures that the cumulative effect of distant encounters is minor in terms of its influence on disc evolution. The angular momentum transfer is dominated by the m = 2 Lindblad resonance for closer encounters and by the m = 1, ω = 0 Lindblad resonance at large xmin/r. We contextualize these results by comparing expected angular momentum loss for the outer edge of a PPD due to distant and close encounters. Contrary to the suggestions of previous works, we do not find that distant encounters contribute significantly to angular momentum loss in PPDs. We define an upper limit for closest approach distance where interactions are significant as a function of arbitrary host to perturber mass ratio M2/M1.

Angular momentum transport by heat-driven g-modes in slowly pulsating B stars

NASA Astrophysics Data System (ADS)

Townsend, R. H. D.; Goldstein, J.; Zweibel, E. G.

2018-03-01

Motivated by recent interest in the phenomenon of waves transport in massive stars, we examine whether the heat-driven gravity (g) modes excited in slowly pulsating B (SPB) stars can significantly modify the stars' internal rotation. We develop a formalism for the differential torque exerted by g modes, and implement this formalism using the GYRE oscillation code and the MESASTAR stellar evolution code. Focusing first on a 4.21M⊙ model, we simulate 1 000 yr of stellar evolution under the combined effects of the torque due to a single unstable prograde g mode (with an amplitude chosen on the basis of observational constraints), and diffusive angular momentum transport due to convection, overshooting, and rotational instabilities. We find that the g mode rapidly extracts angular momentum from the surface layers, depositing it deeper in the stellar interior. The angular momentum transport is so efficient that by the end of the simulation, the initially non-rotating surface layers are spun in the retrograde direction to ≈ 30 per cent of the critical rate. However, the additional inclusion of magnetic stresses in our simulations almost completely inhibits this spin-up. Expanding our simulations to cover the whole instability strip, we show that the same general behaviour is seen in all SPB stars. After providing some caveats to contextualize our results, we hypothesize that the observed slower surface rotation of SPB stars (as compared to other B-type stars) may be the direct consequence of the angular momentum transport that our simulations demonstrate.

Hydrodynamical processes in coalescing binary stars

NASA Astrophysics Data System (ADS)

Lai, Dong

1994-01-01

Coalescing neutron star binaries are considered to be the most promising sources of gravitational waves that could be detected by the planned laser-interferometer LIGO/VIRGO detectors. Extracting gravity wave signals from noisy data requires accurate theoretical waveforms in the frequency range 10-1000 Hz end detailed understanding of the dynamics of the binary orbits. We investigate the quasi-equilibrium and dynamical tidal interactions in coalescing binary stars, with particular focus on binary neutron stars. We develop a new formalism to study the equilibrium and dynamics of fluid stars in binary systems. The stars are modeled as compressible ellipsoids, and satisfy polytropic equation of state. The hydrodynamic equations are reduced to a set of ordinary differential equations for the evolution of the principal axes and other global quantities. The equilibrium binary structure is determined by a set of algebraic equations. We consider both synchronized and nonsynchronized systems, obtaining the generalizations to compressible fluid of the classical results for the ellipsoidal binary configurations. Our method can be applied to a wide variety of astrophysical binary systems containing neutron stars, white dwarfs, main-sequence stars and planets. We find that both secular and dynamical instabilities can develop in close binaries. The quasi-static (secular) orbital evolution, as well as the dynamical evolution of binaries driven by viscous dissipation and gravitational radiation reaction are studied. The development of the dynamical instability accelerates the binary coalescence at small separation, leading to appreciable radial infall velocity near contact. We also study resonant excitations of g-mode oscillations in coalescing binary neutron stars. A resonance occurs when the frequency of the tidal driving force equals one of the intrinsic g-mode frequencies. Using realistic microscopic nuclear equations of state, we determine the g-modes in a cold neutron atar. Resonant excitations of these g-modes during the last few minutes of the binary coalescence result in energy transfer and angular momentum transfer from the binary orbit to the neutron star. Because of the weak coupling between the g-modes and the tidal potential, the induced orbital phase errors due to resonances are small. However, resonant excitations of the g-modes play an important role in the tidal heating of binary neutron stars.

Magnetorotational instability in decretion disks of critically rotating stars and the outer structure of Be and Be/X-ray disks

NASA Astrophysics Data System (ADS)

Krtička, J.; Kurfürst, P.; Krtičková, I.

2015-01-01

Context. Evolutionary models of fast-rotating stars show that the stellar rotational velocity may approach the critical speed. Critically rotating stars cannot spin up more, therefore they lose their excess angular momentum through an equatorial outflowing disk. The radial extension of such disks is unknown, partly because we lack information about the radial variations of the viscosity. Aims: We study the magnetorotational instability, which is considered to be the origin of anomalous viscosity in outflowing disks. Methods: We used analytic calculations to study the stability of outflowing disks submerged in the magnetic field. Results: The magnetorotational instability develops close to the star if the plasma parameter is large enough. At large radii the instability disappears in the region where the disk orbital velocity is roughly equal to the sound speed. Conclusions: The magnetorotational instability is a plausible source of anomalous viscosity in outflowing disks. This is also true in the region where the disk radial velocity approaches the sound speed. The disk sonic radius can therefore be roughly considered as an effective outer disk radius, although disk material may escape from the star to the insterstellar medium. The radial profile of the angular momentum-loss rate already flattens there, consequently, the disk mass-loss rate can be calculated with the sonic radius as the effective disk outer radius. We discuss a possible observation determination of the outer disk radius by using Be and Be/X-ray binaries.

Magnetic braking in young late-type stars. The effect of polar spots

NASA Astrophysics Data System (ADS)

Aibéo, A.; Ferreira, J. M.; Lima, J. J. G.

2007-10-01

Context: The existence of rapidly rotating cool stars in young clusters implies a reduction of angular momentum loss rate for a certain period of the star's early life. Recently, the concentration of magnetic flux near the poles of these stars has been proposed as an alternative mechanism to dynamo saturation in order to explain the saturation of angular momentum loss. Aims: In this work we study the effect of magnetic surface flux distribution on the coronal field topology and angular momentum loss rate. We investigate if magnetic flux concentration towards the pole is a reasonable alternative to dynamo saturation. Methods: We construct a 1D wind model and also apply a 2-D self-similar analytical model, to evaluate how the surface field distribution affects the angular momentum loss of the rotating star. Results: From the 1D model we find that, in a magnetically dominated low corona, the concentrated polar surface field rapidly expands to regions of low magnetic pressure resulting in a coronal field with small latitudinal variation. We also find that the angular momentum loss rate due to a uniform field or a concentrated field with equal total magnetic flux is very similar. From the 2D wind model we show that there are several relevant factors to take into account when studying the angular momentum loss from a star. In particular, we show that the inclusion of force balance across the field in a wind model is fundamental if realistic conclusions are to be drawn from the effect of non-uniform surface field distribution on magnetic braking. This model predicts that a magnetic field concentrated at high latitudes leads to larger Alfvén radii and larger braking rates than a smoother field distribution. Conclusions: From the results obtained, we argue that the magnetic surface field distribution towards the pole does not directly limit the braking efficiency of the wind.

Origins and demonstrations of electrons with orbital angular momentum

PubMed Central

Agrawal, Amit; Ercius, Peter A.; Grillo, Vincenzo; Herzing, Andrew A.; Harvey, Tyler R.; Linck, Martin; Pierce, Jordan S.

2017-01-01

The surprising message of Allen et al. (Allen et al. 1992 Phys. Rev. A 45, 8185 (doi:10.1103/PhysRevA.45.8185)) was that photons could possess orbital angular momentum in free space, which subsequently launched advancements in optical manipulation, microscopy, quantum optics, communications, many more fields. It has recently been shown that this result also applies to quantum mechanical wave functions describing massive particles (matter waves). This article discusses how electron wave functions can be imprinted with quantized phase vortices in analogous ways to twisted light, demonstrating that charged particles with non-zero rest mass can possess orbital angular momentum in free space. With Allen et al. as a bridge, connections are made between this recent work in electron vortex wave functions and much earlier works, extending a 175 year old tradition in matter wave vortices. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069765

Measurement of W boson angular distributions in events with high transverse momentum jets at s = 8   TeV using the ATLAS detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aaboud, M.; Aad, G.; Abbott, B.

The W boson angular distribution in events with high transverse momentum jets is measured using data collected by the ATLAS experiment from proton–proton collisions at a centre-of-mass energy √s=8 TeV at the Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb -1 . The focus is on the contributions to W+jets processes from real W emission, which is achieved by studying events where a muon is observed close to a high transverse momentum jet. At small angular separations, these contributions are expected to be large. Various theoretical models of this process are compared to the data inmore » terms of the absolute cross-section and the angular distributions of the muon from the leptonic W decay.« less

Angular Momentum Transport in Turbulent Flow between Independently Rotating Cylinders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paoletti, M. S.; Lathrop, D. P.; Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742

2011-01-14

We present measurements of the angular momentum flux (torque) in Taylor-Couette flow of water between independently rotating cylinders for all regions of the ({Omega}{sub 1}, {Omega}{sub 2}) parameter space at high Reynolds numbers, where {Omega}{sub 1} ({Omega}{sub 2}) is the inner (outer) cylinder angular velocity. We find that the Rossby number Ro=({Omega}{sub 1}-{Omega}{sub 2})/{Omega}{sub 2} fully determines the state and torque G as compared to G(Ro={infinity}){identical_to}G{sub {infinity}.} The ratio G/G{sub {infinity}} is a linear function of Ro{sup -1} in four sections of the parameter space. For flows with radially increasing angular momentum, our measured torques greatly exceed those of previousmore » experiments [Ji et al., Nature (London), 444, 343 (2006)], but agree with the analysis of Richard and Zahn [Astron. Astrophys. 347, 734 (1999)].« less

Measurement of W boson angular distributions in events with high transverse momentum jets at s = 8   TeV using the ATLAS detector

DOE PAGES

Aaboud, M.; Aad, G.; Abbott, B.; ...

2016-12-06

The W boson angular distribution in events with high transverse momentum jets is measured using data collected by the ATLAS experiment from proton–proton collisions at a centre-of-mass energy √s=8 TeV at the Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb -1 . The focus is on the contributions to W+jets processes from real W emission, which is achieved by studying events where a muon is observed close to a high transverse momentum jet. At small angular separations, these contributions are expected to be large. Various theoretical models of this process are compared to the data inmore » terms of the absolute cross-section and the angular distributions of the muon from the leptonic W decay.« less

Energy-dependent angular shifts in the photoelectron momentum distribution for atoms in elliptically polarized laser pulses

NASA Astrophysics Data System (ADS)

Xie, Hui; Li, Min; Luo, Siqiang; Li, Yang; Zhou, Yueming; Cao, Wei; Lu, Peixiang

2017-12-01

We measure the photoelectron momentum distributions from atoms ionized by strong elliptically polarized laser fields at the wavelengths of 400 and 800 nm, respectively. The momentum distributions show distinct angular shifts, which sensitively depend on the electron energy. We find that the deflection angle with respect to the major axis of the laser ellipse decreases with the increase of the electron energy for large ellipticities. This energy-dependent angular shift is well reproduced by both numerical solutions of the time-dependent Schrödinger equation and the classical-trajectory Monte Carlo model. We show that the ionization time delays among the electrons with different energies are responsible for the energy-dependent angular shifts. On the other hand, for small ellipticities, we find the deflection angle increases with increasing the electron energy, which might be caused by electron rescattering in the elliptically polarized fields.

Tidal evolution in close binary systems.

NASA Technical Reports Server (NTRS)

Kopal, Z.

1972-01-01

Mathematical outline of the theory of tidal evolution in close binary systems of secularly constant total momentum. Following a general outline of the problem the basic expressions for the energy and momenta of close binaries consisting of components of arbitrary internal structure are established, and the maximum and minimum values of the energy (kinetic and potential) which such systems can attain for a given amount of total momentum are investigated. These results are compared with the actual facts encountered in binaries with components whose internal structure (and, therefore, rotational momenta) are known from evidence furnished by the observed rates of apsidal advance. The results show that all such systems whether of detached or semidetached type - disclose that more than 99% of their total momenta are stored in the orbital momentum. The sum of the rotational momenta of the constituent components amounts to less than 1% of the total -a situation characteristic of a state close to the minimum energy for given total momentum.

Amplification of Angular Rotations Using Weak Measurements

NASA Astrophysics Data System (ADS)

Magaña-Loaiza, Omar S.; Mirhosseini, Mohammad; Rodenburg, Brandon; Boyd, Robert W.

2014-05-01

We present a weak measurement protocol that permits a sensitive estimation of angular rotations based on the concept of weak-value amplification. The shift in the state of a pointer, in both angular position and the conjugate orbital angular momentum bases, is used to estimate angular rotations. This is done by an amplification of both the real and imaginary parts of the weak-value of a polarization operator that has been coupled to the pointer, which is a spatial mode, via a spin-orbit coupling. Our experiment demonstrates the first realization of weak-value amplification in the azimuthal degree of freedom. We have achieved effective amplification factors as large as 100, providing a sensitivity that is on par with more complicated methods that employ quantum states of light or extremely large values of orbital angular momentum.

Motion of the angular momentum vector in body coordinates for torque-free dual-spin spacecraft

NASA Technical Reports Server (NTRS)

Fedor, J. V.

1981-01-01

The motion of the angular momentum vector in body coordinates for torque free, asymmetric dual spin spacecraft without and, for a special case, with energy dissipation on the main spacecraft is investigated. Without energy dissipation, two integrals can be obtained from the Euler equations of motion. Using the classical method of elimination of variable, the motion about the equilibrium points (six for the general case) are derived with these integrals. For small nutation angle, theta, the trajectories about the theta = 0 deg and theta = 180 deg points readily show the requirements for stable motion about these points. Also the conditions needed to eliminate stable motion about the theta = 180 deg point as well as the other undesireable equilibrium points follow directly from these equations. For the special case where the angular momentum vector moves about the principal axis which contains the momentum wheel, the notion of 'free variable' azimuth angle is used. Physically this angle must vary from 0 to 2 pi in a circular periodic fashion. Expressions are thus obtained for the nutation angle in terms of the free variable and other spacecraft parameters. Results show that in general there are two separate trajectory expressions that govern the motion of the angular momentum vector in body coordinates.

Conserved Quantities in General Relativity: From the Quasi-Local Level to Spatial Infinity

NASA Astrophysics Data System (ADS)

Chen, Po-Ning; Wang, Mu-Tao; Yau, Shing-Tung

2015-08-01

We define quasi-local conserved quantities in general relativity by using the optimal isometric embedding in Wang and Yau (Commun Math Phys 288(3):919-942, 2009) to transplant Killing fields in the Minkowski spacetime back to the 2-surface of interest in a physical spacetime. To each optimal isometric embedding, a dual element of the Lie algebra of the Lorentz group is assigned. Quasi-local angular momentum and quasi-local center of mass correspond to pairing this element with rotation Killing fields and boost Killing fields, respectively. They obey classical transformation laws under the action of the Poincaré group. We further justify these definitions by considering their limits as the total angular momentum and the total center of mass of an isolated system. These expressions were derived from the Hamilton-Jacobi analysis of the gravitational action and thus satisfy conservation laws. As a result, we obtained an invariant total angular momentum theorem in the Kerr spacetime. For a vacuum asymptotically flat initial data set of order 1, it is shown that the limits are always finite without any extra assumptions. We also study these total conserved quantities on a family of asymptotically flat initial data sets evolving by the vacuum Einstein evolution equation. It is shown that the total angular momentum is conserved under the evolution. For the total center of mass, the classical dynamical formula relating the center of mass, energy, and linear momentum is recovered, in the nonlinear context of initial data sets evolving by the vacuum Einstein evolution equation. The definition of quasi-local angular momentum provides an answer to the second problem in classical general relativity on Penrose's list (Proc R Soc Lond Ser A 381(1780):53-63, 1982).

Critical gravitational collapse with angular momentum. II. Soft equations of state

NASA Astrophysics Data System (ADS)

Gundlach, Carsten; Baumgarte, Thomas W.

2018-03-01

We study critical phenomena in the collapse of rotating ultrarelativistic perfect fluids, in which the pressure P is related to the total energy density ρ by P =κ ρ , where κ is a constant. We generalize earlier results for radiation fluids with κ =1 /3 to other values of κ , focusing on κ <1 /9 . For 1 /9 <κ ≲0.49 , the critical solution has only one unstable, growing mode, which is spherically symmetric. For supercritical data it controls the black-hole mass, while for subcritical data it controls the maximum density. For κ <1 /9 , an additional axial l =1 mode becomes unstable. This controls either the black-hole angular momentum, or the maximum angular velocity. In theory, the additional unstable l =1 mode changes the nature of the black-hole threshold completely: at sufficiently large initial rotation rates Ω and sufficient fine-tuning of the initial data to the black-hole threshold we expect to observe nontrivial universal scaling functions (familiar from critical phase transitions in thermodynamics) governing the black-hole mass and angular momentum, and, with further fine-tuning, eventually a finite black-hole mass almost everywhere on the threshold. In practice, however, the second unstable mode grows so slowly that we do not observe this breakdown of scaling at the level of fine-tuning we can achieve, nor systematic deviations from the leading-order power-law scalings of the black-hole mass. We do see systematic effects in the black-hole angular momentum, but it is not clear yet if these are due to the predicted nontrivial scaling functions, or to nonlinear effects at sufficiently large initial angular momentum (which we do not account for in our theoretical model).

Photonic Interrogation and Control of Nano Processes

NASA Technical Reports Server (NTRS)

Jassemnejad, Baha

2003-01-01

My research activities for the summer of 2003 consisted of two projects: One project was concerned with determining a method for predicting the static and dynamic assembly properties of nano-structures using laser tweezers. The other project was to investigate the generation of Laguerre-Gaussian modes using a spatial light modulator incorporated into an optical tweezers system. Concerning the first project, I initially pursued the approach suggested by my NASA colleague Dr. Art Decker. This approach involved mimicking the model of the structure of atomic nucleus for the assembly of 1 to 100 atoms using allowed quadruple transitions induced by orbital angular momentums of a Laguerre- Gaussian (Doughnut) laser mode. After realizing the inaptness of the nuclear model with the nanostructure model as far as the binding forces and transitions were concerned, I focused on using quantum dot modei. This model was not attuned also for the host lattice influences the electronic structure of the quantum dot. Thus one other option that I decided to pursue was the approach of molecular quantum mechanics. In this approach the nanostructure is treated as a large (10-100 nm) molecule constructed from single element or multi-elements. Subsequent to consultation with Dr. Fred Morales, a chemical engineer at NASA GRC, and Dr. David Ball, a computational chemist at Cleveland State University, I acquired a molecular-quantum computation software, Hyperchem 7.0. This software allows simulation of different molecular structures as far as their static and dynamic behaviors are concerned. The time that I spent on this project was about eight weeks. Once this suitable approach was identified, I realized the need to collaborate with a computational quantum chemist to pursue searching for stable nanostructures in the range of 10-100 nm that we can be assembled using laser tweezers. The second project was about generating laser tweezers that possess orbital angular momentum. As shown, we were able to generate laser tweezers modes of different orbital angular momentum using a spatial light modulator incorporated into a laser tweezers system. The motivation for investigating these types of modes stems from being able to spin particles at high speeds and also to orient two particles in separate traps and then join them together. Also, there has been recent intense interest on fundamental physics research on orbital angular momentum of light. The fact that circularly polarized light may have associated with it angular momentum that relates to the spin of individual photons (spin 0 for the plane polarized light, spin +1 for the right-circularly polarized light and spin -1 for the left-circularly polarized light) was first demonstrated by Beth in 1936. Orbital angular momentum is, however, distinct from spin in that the spin angular momentum of light is intrinsically linked to the behavior of the electric field in the light whereas orbital angular momentum is a consequence of inclined wavefronts. In 1992 L. Allen, et al showed that the Laguerre-Gaussian (LG) modes could possess well-defined orbital angular momentum that can exceed 1 planck's constant, i.e. l plancks constant per photon, where l is the azimuthal index of the mode.

Toward higher order tests of the gravitational interaction

NASA Technical Reports Server (NTRS)

Nordtvedt, Ken

1989-01-01

Analyses and interpretations of experiments which test post-Newtonian gravity are usually done under the assumption that gravity is a metric field phenomenon - a manifestation of space-time geometry. This, however, is unnecessary and one can start at a more primitive level - that there simply exists a phenomenological, gravitational, many-body equation of motion which must be determined by a package of observations. In fact, over the last couple decades, a diverse collection of solar system interbody tracking observations, supplemented by data from the binary pulsar system PSR 1913 + 16, has completely mapped out the first post-Newtonian order. After the fact, using empirically determined equations of motion, along with some observed properties of nongravitational clocks and rulers and conservation laws for energy, momentum and angular momentum, a post-Newtonian Lagrangian can be constructed, a geometrical space-time metric field conceptual interpretation can be developed, Lorentz invariance of the equations of motion can be shown, and the equations of motion are found to agree with the predictions of Einstein's gravitational theory, General Relativity, within experimental accuracy.

Three-body Coulomb systems using generalized angular-momentum S states

NASA Technical Reports Server (NTRS)

Whitten, R. C.; Sims, J. S.

1974-01-01

An expansion of the three-body Coulomb potential in generalized angular-momentum eigenfunctions developed earlier by one of the authors is used to compute energy eigenvalues and eigenfunctions of bound S states of three-body Coulomb systems. The results for He, H(-), e(-)e(+)e(-), and pmu(-)p are compared with the results of other computational approaches.

Investigating Students' Mental Models about the Quantization of Light, Energy, and Angular Momentum

ERIC Educational Resources Information Center

Didis, Nilüfer; Eryilmaz, Ali; Erkoç, Sakir

2014-01-01

This paper is the first part of a multiphase study examining students' mental models about the quantization of physical observables--light, energy, and angular momentum. Thirty-one second-year physics and physics education college students who were taking a modern physics course participated in the study. The qualitative analysis of data revealed…

Counting relative equilibrium configurations of the full two-body problem

NASA Astrophysics Data System (ADS)

Moeckel, Richard

2018-02-01

Consider a system of two rigid, massive bodies interacting according to their mutual gravitational attraction. In a relative equilibrium motion, the bodies rotate rigidly and uniformly about a fixed axis in R^3. This is possible only for special positions and orientations of the bodies. After fixing the angular momentum, these relative equilibrium configurations can be characterized as critical points of a smooth function on configuration space. The goal of this paper is to use Morse theory and Lusternik-Schnirelmann category theory to give lower bounds for the number of critical points when the angular momentum is sufficiently large. In addition, the exact number of critical points and their Morse indices are found in the limit as the angular momentum tends to infinity.

Probing the degenerate states of V-point singularities.

PubMed

Ram, B S Bhargava; Sharma, Anurag; Senthilkumaran, Paramasivam

2017-09-15

V-points are polarization singularities in spatially varying linearly polarized optical fields and are characterized by the Poincare-Hopf index η. Each V-point singularity is a superposition of two oppositely signed orbital angular momentum states in two orthogonal spin angular momentum states. Hence, a V-point singularity has zero net angular momentum. V-points with given |η| have the same (amplitude) intensity distribution but have four degenerate polarization distributions. Each of these four degenerate states also produce identical diffraction patterns. Hence to distinguish these degenerate states experimentally, we present in this Letter a method involving a combination of polarization transformation and diffraction. This method also shows the possibility of using polarization singularities in place of phase singularities in optical communication and quantum information processing.

Compensation for the orbital angular momentum of a vortex beam in turbulent atmosphere by adaptive optics

NASA Astrophysics Data System (ADS)

Li, Nan; Chu, Xiuxiang; Zhang, Pengfei; Feng, Xiaoxing; Fan, ChengYu; Qiao, Chunhong

2018-01-01

A method which can be used to compensate for a distorted orbital angular momentum and wavefront of a beam in atmospheric turbulence, simultaneously, has been proposed. To confirm the validity of the method, an experimental setup for up-link propagation of a vortex beam in a turbulent atmosphere has been simulated. Simulation results show that both of the distorted orbital angular momentum and the distorted wavefront of a beam due to turbulence can be compensated by an adaptive optics system with the help of a cooperative beacon at satellite. However, when the number of the lenslet of wavefront sensor (WFS) and the actuators of the deform mirror (DM) is small, satisfactory results cannot be obtained.

Relative and absolute level populations in beam-foil-excited neutral helium

NASA Technical Reports Server (NTRS)

Davidson, J.

1975-01-01

Relative and absolute populations of 19 levels in beam-foil-excited neutral helium at 0.275 MeV have been measured. The singlet angular-momentum sequences show dependences on principal quantum number consistent with n to the -3rd power, but the triplet sequences do not. Singlet and triplet angular-momentum sequences show similar dependences on level excitation energy. Excitation functions for six representative levels were measured in the range from 0.160 to 0.500 MeV. The absolute level populations increase with energy, whereas the neutral fraction of the beam decreases with energy. Further, the P angular-momentum levels are found to be overpopulated with respect to the S and D levels. The overpopulation decreases with increasing principal quantum number.

Resilience of hybrid optical angular momentum qubits to turbulence

PubMed Central

Farías, Osvaldo Jiménez; D'Ambrosio, Vincenzo; Taballione, Caterina; Bisesto, Fabrizio; Slussarenko, Sergei; Aolita, Leandro; Marrucci, Lorenzo; Walborn, Stephen P.; Sciarrino, Fabio

2015-01-01

Recent schemes to encode quantum information into the total angular momentum of light, defining rotation-invariant hybrid qubits composed of the polarization and orbital angular momentum degrees of freedom, present interesting applications for quantum information technology. However, there remains the question as to how detrimental effects such as random spatial perturbations affect these encodings. Here, we demonstrate that alignment-free quantum communication through a turbulent channel based on hybrid qubits can be achieved with unit transmission fidelity. In our experiment, alignment-free qubits are produced with q-plates and sent through a homemade turbulence chamber. The decoding procedure, also realized with q-plates, relies on both degrees of freedom and renders an intrinsic error-filtering mechanism that maps errors into losses. PMID:25672667

Role of photonic angular momentum states in nonreciprocal diffraction from magneto-optical cylinder arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Tian-Jing; Wu, Li-Ting; Yang, Mu

2014-07-15

Optical eigenstates in a concentrically symmetric resonator are photonic angular momentum states (PAMSs) with quantized optical orbital angular momentums (OAMs). Nonreciprocal optical phenomena can be obtained if we lift the degeneracy of PAMSs. In this article, we provide a comprehensive study of nonreciprocal optical diffraction of various orders from a magneto-optical cylinder array. We show that nonreciprocal diffraction can be obtained only for these nonzero orders. Role of PAMSs, the excitation of which is sensitive to the directions of incidence, applied magnetic field, and arrangement of the cylinders, are studied. Some interesting phenomena such as a dispersionless quasi-omnidirectional nonreciprocal diffractionmore » and spikes associated with high-OAM PAMSs are present and discussed.« less

A tidal theory for the origin of the solar nebula

NASA Technical Reports Server (NTRS)

Kobrick, M.; Kaula, W. M.

1979-01-01

A model for the origin of the solar nebula is developed with attention to the significance of angular momentum considerations. Evidence that stars are born in groups rather than singly is examined. It is shown that protostars which are members of typical galactic clusters have some probability of undergoing a gravitational encounter with another star while they are collapsing. According to the model, these encounters impart disproportionate amounts of angular momentum to the later material to fall in toward already centrally condensed fragments. The amount of central condensation of a fragment is the overriding factor in determining its stability against destruction by tidal forces. The encounter also imparts angular momentum to matter that is still accreting onto the protosun.

Dark halos formed via dissipationless collapse. I - Shapes and alignment of angular momentum

NASA Astrophysics Data System (ADS)

Warren, Michael S.; Quinn, Peter J.; Salmon, John K.; Zurek, Wojciech H.

1992-11-01

We use N-body simulations on highly parallel supercomputers to study the structure of Galactic dark matter halos. The systems form by gravitational collapse from scale-free and more general Gaussian initial density perturbations in an expanding 400 Mpc-cubed spherical slice of an Einstein-deSitter universe. We analyze the structure and kinematics of about 100 of the largest relaxed halos in each of 10 separate simulations. A typical halo is a triaxial spheroid which tends to be more often prolate than oblate. These shapes are maintained by anisotropic velocity dispersion rather than by angular momentum. Nevertheless, there is a significant tendency for the total angular momentum vector to be aligned with the minor axis of the density distribution.

Energy and Momentum Transport in String Waves

ERIC Educational Resources Information Center

Juenker, D. W.

1976-01-01

Formulas are derived for the energy, momentum, and angular momentum transmitted by waves of arbitrary shape in an inextensible string by pure transverse waves in a string using Tait's procedure. (Author/CP)

THE IMPACT OF STELLAR FEEDBACK ON THE STRUCTURE, SIZE, AND MORPHOLOGY OF GALAXIES IN MILKY-WAY-SIZED DARK MATTER HALOS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agertz, Oscar; Kravtsov, Andrey V., E-mail: o.agertz@surrey.ac.uk

We use cosmological zoom-in simulations of galaxy formation in a Milky-Way-sized halo started from identical initial conditions to investigate the evolution of galaxy sizes, baryon fractions, morphologies, and angular momenta in runs with different parameters of the star formation–feedback cycle. Our fiducial model with a high local star formation efficiency, which results in efficient feedback, produces a realistic late-type galaxy that matches the evolution of basic properties of late-type galaxies: stellar mass, disk size, morphology dominated by a kinematically cold disk, stellar and gas surface density profiles, and specific angular momentum. We argue that feedback’s role in this success ismore » twofold: (1) removal of low angular momentum gas, and (2) maintaining a low disk-to-halo mass fraction, which suppresses disk instabilities that lead to angular momentum redistribution and a central concentration of baryons. However, our model with a low local star formation efficiency, but large energy input per supernova, chosen to produce a galaxy with a similar star formation history as our fiducial model, leads to a highly irregular galaxy with no kinematically cold component, overly extended stellar distribution, and low angular momentum. This indicates that only when feedback is allowed to become vigorous via locally efficient star formation in dense cold gas do resulting galaxy sizes, gas/stellar surface density profiles, and stellar disk angular momenta agree with observed z = 0 galaxies.« less

The Formation of Rapidly Rotating Black Holes in High-mass X-Ray Binaries

DOE PAGES

Batta, Aldo; Ramirez-Ruiz, Enrico; Fryer, Chris Lee

2017-09-01

In this paper, high-mass X-ray binaries (HMXRBs), such as Cygnus X-1, host some of the most rapidly spinning black holes (BHs) known to date, reaching spin parametersmore » $$a\\gtrsim 0.84$$. However, there are several effects that can severely limit the maximum BH spin parameter that could be obtained from direct collapse, such as tidal synchronization, magnetic core-envelope coupling, and mass loss. Here, we propose an alternative scenario where the BH is produced by a failed supernova (SN) explosion that is unable to unbind the stellar progenitor. A large amount of fallback material ensues, whose interaction with the secondary naturally increases its overall angular momentum content, and therefore the spin of the BH when accreted. Through SPH hydrodynamic simulations, we studied the unsuccessful explosion of an $$8\\,{M}_{\\odot }$$ pre-SN star in a close binary with a $$12\\,{M}_{\\odot }$$ companion with an orbital period of ≈1.2 days, finding that it is possible to obtain a BH with a high spin parameter $$a\\gtrsim 0.8$$ even when the expected spin parameter from direct collapse is $$a\\lesssim 0.3$$. This scenario also naturally explains the atmospheric metal pollution observed in HMXRB stellar companions.« less

General Relativistic Effects and QPOs in X-Ray Binaries

NASA Astrophysics Data System (ADS)

Markovic, D.; Lamb, F. K.

We have investigated whether general relativistic effects may be responsible for some of the quasi-periodic X-ray brightness oscillations (QPOs) observed in low-mass binary systems containing accreting neutron stars and black hole candidates. In particular, we have computed the motions of accreting gas in the strong gravitational fields near such objects and have explored possible mechanisms for producing X-ray flux oscillations. We have discovered a family of weakly damped global gravitomagnetic (Lense-Thirring) warping modes of the inner (viscous) accretion disk that have precession frequencies ranging up to the single-particle gravitomagnetic precession frequency at the inner edge of the disk, which is about 30 Hz if the disk extends inward to the innermost stable circular orbit around a compact object of solar mass with dimensionless angular momentum cJ/GM2 ~ 0.2. Precession of regions of enhanced viscous dissipation or modulation of the accretion flow by the precession may produce observable periodic variation of the X-ray flux. Detectable effects might also be produced if the gas in the inner disk breaks up into a collection of distinct clumps. We have analyzed the dynamics of such clumps as well as the conditions required for their formation and survival on time scales long enough to produce QPOs with the coherence observed in low-mass X-ray binaries.

The Formation of Rapidly Rotating Black Holes in High-mass X-Ray Binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batta, Aldo; Ramirez-Ruiz, Enrico; Fryer, Chris Lee

In this paper, high-mass X-ray binaries (HMXRBs), such as Cygnus X-1, host some of the most rapidly spinning black holes (BHs) known to date, reaching spin parametersmore » $$a\\gtrsim 0.84$$. However, there are several effects that can severely limit the maximum BH spin parameter that could be obtained from direct collapse, such as tidal synchronization, magnetic core-envelope coupling, and mass loss. Here, we propose an alternative scenario where the BH is produced by a failed supernova (SN) explosion that is unable to unbind the stellar progenitor. A large amount of fallback material ensues, whose interaction with the secondary naturally increases its overall angular momentum content, and therefore the spin of the BH when accreted. Through SPH hydrodynamic simulations, we studied the unsuccessful explosion of an $$8\\,{M}_{\\odot }$$ pre-SN star in a close binary with a $$12\\,{M}_{\\odot }$$ companion with an orbital period of ≈1.2 days, finding that it is possible to obtain a BH with a high spin parameter $$a\\gtrsim 0.8$$ even when the expected spin parameter from direct collapse is $$a\\lesssim 0.3$$. This scenario also naturally explains the atmospheric metal pollution observed in HMXRB stellar companions.« less

A magnetic accretion switch in pre-cataclysmic binaries

NASA Astrophysics Data System (ADS)

Drake, Jeremy J.; Garraffo, Cecilia; Takei, Dai; Gaensicke, Boris

2014-02-01

We have investigated the mass accretion rate implied by published surface abundances of Si and C in the white dwarf component of the 3.62 h period pre-cataclysmic binary and planet host candidate QS Vir (DA+M2-4). Diffusion time-scales for gravitational settling imply dot{M} ˜ 10^{-16} M_{odot } yr-1 for the 1999 epoch of the observations, which is three orders of magnitude lower than measured from a 2006 XMM-Newton observation. This is the first time that large accretion rate variations have been seen in a detached pre-cataclysmic variable (pre-CV). A third body in a 14 yr eccentric orbit suggested in a recent eclipse timing study is too distant to perturb the central binary sufficiently to influence accretion. A hypothetical coronal mass ejection just prior to the XMM-Newton observation might explain the higher accretion rate, but the implied size and frequency of such events appear too great. We suggest accretion is most likely modulated by a magnetic cycle on the secondary acting as a wind `accretion switch', a mechanism that can be tested by X-ray and ultraviolet monitoring. If so, QS Vir and similar pre-CVs could provide powerful insights into hitherto inscrutable CV and M dwarf magnetospheres, and mass- and angular-momentum-loss rates.

FORMATION OF STABLE MAGNETARS FROM BINARY NEUTRON STAR MERGERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giacomazzo, Bruno; Perna, Rosalba

2013-07-10

By performing fully general relativistic magnetohydrodynamic simulations of binary neutron star mergers, we investigate the possibility that the end result of the merger is a stable magnetar. In particular, we show that, for a binary composed of two equal-mass neutron stars (NSs) of gravitational mass M {approx} 1.2 M{sub Sun} and equation of state similar to Shen et al. at high densities, the merger product is a stable NS. Such NS is found to be differentially rotating and ultraspinning with spin parameter J/M{sup 2} {approx} 0.86, where J is its total angular momentum, and it is surrounded by a diskmore » of Almost-Equal-To 0.1 M{sub Sun }. While in our global simulations the magnetic field is amplified by about two orders of magnitude, local simulations have shown that hydrodynamic instabilities and the onset of the magnetorotational instability could further increase the magnetic field strength up to magnetar levels. This leads to the interesting possibility that, for some NS mergers, a stable and magnetized NS surrounded by an accretion disk could be formed. We discuss the impact of these new results for the emission of electromagnetic counterparts of gravitational wave signals and for the central engine of short gamma-ray bursts.« less

General relativistic viscous hydrodynamics of differentially rotating neutron stars

NASA Astrophysics Data System (ADS)

Shibata, Masaru; Kiuchi, Kenta; Sekiguchi, Yu-ichiro

2017-04-01

Employing a simplified version of the Israel-Stewart formalism for general-relativistic shear-viscous hydrodynamics, we perform axisymmetric general-relativistic simulations for a rotating neutron star surrounded by a massive torus, which can be formed from differentially rotating stars. We show that with our choice of a shear-viscous hydrodynamics formalism, the simulations can be stably performed for a long time scale. We also demonstrate that with a possibly high shear-viscous coefficient, not only viscous angular momentum transport works but also an outflow could be driven from a hot envelope around the neutron star for a time scale ≳100 ms with the ejecta mass ≳10-2 M⊙ , which is comparable to the typical mass for dynamical ejecta of binary neutron-star mergers. This suggests that massive neutron stars surrounded by a massive torus, which are typical outcomes formed after the merger of binary neutron stars, could be the dominant source for providing neutron-rich ejecta, if the effective shear viscosity is sufficiently high, i.e., if the viscous α parameter is ≳10-2. The present numerical result indicates the importance of a future high-resolution magnetohydrodynamics simulation that is the unique approach to clarify the viscous effect in the merger remnants of binary neutron stars by the first-principle manner.

Radius of the neutron star magnetosphere during disk accretion

NASA Astrophysics Data System (ADS)

Filippova, E. V.; Mereminskiy, I. A.; Lutovinov, A. A.; Molkov, S. V.; Tsygankov, S. S.

2017-11-01

The dependence of the spin frequency derivative \\dot ν of accreting neutron stars with a strongmagnetic field (X-ray pulsars) on the mass accretion rate (bolometric luminosity, L bol) has been investigated for eight transient pulsars in binary systems with Be stars. Using data from the Fermi/GBM and Swift/BAT telescopes, we have shown that for seven of the eight systems the dependence \\dot ν ( L bol) can be fitted by the model of angular momentum transfer through an accretion disk, which predicts the relation \\dot ν ˜ L 6/7 bol. Hysteresis in the dependence \\dot ν ( L bol) has been confirmed in the system V 0332+53 and has been detected for the first time in the systems KS 1947+300, GRO J1008-57, and 1A 0535+26. Estimates for the radius of the neutron star magnetosphere in all of the investigated systems have been obtained. We show that this quantity varies from pulsar to pulsar and depends strongly on the analytical model and the estimates for the neutron star and binary system parameters.

Stochastic Template Bank for Gravitational Wave Searches for Precessing Neutron Star-Black Hole Coalescence Events

NASA Technical Reports Server (NTRS)

Indik, Nathaniel; Haris, K.; Dal Canton, Tito; Fehrmann, Henning; Krishnan, Badri; Lundgren, Andrew; Nielsen, Alex B.; Pai, Archana

2017-01-01

Gravitational wave searches to date have largely focused on non-precessing systems. Including precession effects greatly increases the number of templates to be searched over. This leads to a corresponding increase in the computational cost and can increase the false alarm rate of a realistic search. On the other hand, there might be astrophysical systems that are entirely missed by non-precessing searches. In this paper we consider the problem of constructing a template bank using stochastic methods for neutron star-black hole binaries allowing for precession, but with the restrictions that the total angular momentum of the binary is pointing toward the detector and that the neutron star spin is negligible relative to that of the black hole. We quantify the number of templates required for the search, and we explicitly construct the template bank. We show that despite the large number of templates, stochastic methods can be adapted to solve the problem. We quantify the parameter space region over which the non-precessing search might miss signals.

Not an Oxymoron: Some X-ray Binary Pulsars with Enormous Spinup Rates Reveal Weak Magnetic Fields

NASA Astrophysics Data System (ADS)

Christodoulou, D. M.; Laycock, S. G. T.; Kazanas, D.

2018-05-01

Three high-mass X-ray binaries have been discovered recently exhibiting enormous spinup rates. Conventional accretion theory predicts extremely high surface dipolar magnetic fields that we believe are unphysical. Instead, we propose quite the opposite scenario: some of these pulsars exhibit weak magnetic fields, so much so that their magnetospheres are crushed by the weight of inflowing matter. The enormous spinup rate is achieved before inflowing matter reaches the pulsar's surface as the penetrating inner disk transfers its excess angular momentum to the receding magnetosphere which, in turn, applies a powerful spinup torque to the pulsar. This mechanism also works in reverse: it spins a pulsar down when the magnetosphere expands beyond corotation and finds itself rotating faster than the accretion disk which then exerts a powerful retarding torque to the magnetic field and to the pulsar itself. The above scenaria cannot be accommodated within the context of neutron-star accretion processes occurring near spin equilibrium, thus they constitute a step toward a new theory of extreme (far from equilibrium) accretion phenomena.

Hovering Dual-Spin Vehicle Groundwork for Bias Momentum Sizing Validation Experiment

NASA Technical Reports Server (NTRS)

Rothhaar, Paul M.; Moerder, Daniel D.; Lim, Kyong B.

2008-01-01

Angular bias momentum offers significant stability augmentation for hovering flight vehicles. The reliance of the vehicle on thrust vectoring for agility and disturbance rejection is greatly reduced with significant levels of stored angular momentum in the system. A methodical procedure for bias momentum sizing has been developed in previous studies. This current study provides groundwork for experimental validation of that method using an experimental vehicle called the Dual-Spin Test Device, a thrust-levitated platform. Using measured data the vehicle's thrust vectoring units are modeled and a gust environment is designed and characterized. Control design is discussed. Preliminary experimental results of the vehicle constrained to three rotational degrees of freedom are compared to simulation for a case containing no bias momentum to validate the simulation. A simulation of a bias momentum dominant case is presented.

IMPLICATIONS OF RAPID CORE ROTATION IN RED GIANTS FOR INTERNAL ANGULAR MOMENTUM TRANSPORT IN STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tayar, Jamie; Pinsonneault, Marc H., E-mail: tayar.1@osu.edu

2013-09-20

Core rotation rates have been measured for red giant stars using asteroseismology. These data, along with helioseismic measurements and open cluster spin-down studies, provide powerful clues about the nature and timescale for internal angular momentum transport in stars. We focus on two cases: the metal-poor red giant KIC 7341231 ({sup O}tto{sup )} and intermediate-mass core helium burning stars. For both, we examine limiting case studies for angular momentum coupling between cores and envelopes under the assumption of rigid rotation on the main sequence. We discuss the expected pattern of core rotation as a function of mass and radius. In themore » case of Otto, strong post-main-sequence coupling is ruled out and the measured core rotation rate is in the range of 23-33 times the surface value expected from standard spin-down models. The minimum coupling timescale (0.17-0.45 Gyr) is significantly longer than that inferred for young open cluster stars. This implies ineffective internal angular momentum transport in early first ascent giants. By contrast, the core rotation rates of evolved secondary clump stars are found to be consistent with strong coupling given their rapid main-sequence rotation. An extrapolation to the white dwarf regime predicts rotation periods between 330 and 0.0052 days, depending on mass and decoupling time. We identify two key ingredients that explain these features: the presence of a convective core and inefficient angular momentum transport in the presence of larger mean molecular weight gradients. Observational tests that can disentangle these effects are discussed.« less

Evidence for Cluster to Cluster Variations in Low-mass Stellar Rotational Evolution

NASA Astrophysics Data System (ADS)

Coker, Carl T.; Pinsonneault, Marc; Terndrup, Donald M.

2016-12-01

The concordance model for angular momentum evolution postulates that star-forming regions and clusters are an evolutionary sequence that can be modeled with assumptions about protostar-disk coupling, angular momentum loss from magnetized winds that saturates in a mass-dependent fashion at high rotation rates, and core-envelope decoupling for solar analogs. We test this approach by combining established data with the large h Per data set from the MONITOR project and new low-mass Pleiades data. We confirm prior results that young low-mass stars can be used to test star-disk coupling and angular momentum loss independent of the treatment of internal angular momentum transport. For slow rotators, we confirm the need for star-disk interactions to evolve the ONC to older systems, using h Per (age 13 Myr) as our natural post-disk case. There is no evidence for extremely long-lived disks as an alternative to core-envelope decoupling. However, our wind models cannot evolve rapid rotators from h Per to older systems consistently, and we find that this result is robust with respect to the choice of angular momentum loss prescription. We outline two possible solutions: either there is cosmic variance in the distribution of stellar rotation rates in different clusters or there are substantially enhanced torques in low-mass rapid rotators. We favor the former explanation and discuss observational tests that could be used to distinguish them. If the distribution of initial conditions depends on environment, models that test parameters by assuming a universal underlying distribution of initial conditions will need to be re-evaluated.

Elliptical optical solitary waves in a finite nematic liquid crystal cell

NASA Astrophysics Data System (ADS)

Minzoni, Antonmaria A.; Sciberras, Luke W.; Smyth, Noel F.; Worthy, Annette L.

2015-05-01

The addition of orbital angular momentum has been previously shown to stabilise beams of elliptic cross-section. In this article the evolution of such elliptical beams is explored through the use of an approximate methodology based on modulation theory. An approximate method is used as the equations that govern the optical system have no known exact solitary wave solution. This study brings to light two distinct phases in the evolution of a beam carrying orbital angular momentum. The two phases are determined by the shedding of radiation in the form of mass loss and angular momentum loss. The first phase is dominated by the shedding of angular momentum loss through spiral waves. The second phase is dominated by diffractive radiation loss which drives the elliptical solitary wave to a steady state. In addition to modulation theory, the "chirp" variational method is also used to study this evolution. Due to the significant role radiation loss plays in the evolution of an elliptical solitary wave, an attempt is made to couple radiation loss to the chirp variational method. This attempt furthers understanding as to why radiation loss cannot be coupled to the chirp method. The basic reason for this is that there is no consistent manner to match the chirp trial function to the generated radiating waves which is uniformly valid in time. Finally, full numerical solutions of the governing equations are compared with solutions obtained using the various variational approximations, with the best agreement achieved with modulation theory due to its ability to include both mass and angular momentum losses to shed diffractive radiation.

Fueling the AGN

NASA Astrophysics Data System (ADS)

Combes, F.

Active Galactic Nuclei are fueled from material (gas or stars) that are in general far away from the gravitational influence of the central black hole, the engine thought to be responsible for their activity. The required material has a lot of angular momentum that, a priori, is quite difficult to evacuate. The various dynamical mechanisms that may play a role in this game are reviewed, including m = 2 perturbations (bars and spirals), m = 1 perturbations (spirals, warps, lopsidedness), and tidal interactions between galaxies and mergers. In the latest stages of the merger, a binary black hole could be formed, and its influence on the dynamics and fueling is discussed. Starbursts are often associated with AGN, and the nature of their particular connection, and their role in the nuclear fueling is described. Evolution of the fueling efficiency with redshift is addressed.

Inheritance of magma ocean differentiation during lunar origin by giant impact

NASA Technical Reports Server (NTRS)

Warren, Paul H.

1992-01-01

The giant impact model for the Moon has won widespread support. It seems to satisfactorily explain the high angular momentum of the Earth-Moon system, and the strong depletion of FeNi in the Moon. This model is usually assumed to entail no significant fractionation of nonvolatile lithophile elements relative to a simple binary mixture of impactor silicates plus protoearth silicates. Although the Earth may have been hot enough before the impact to be completely molten, analysis of the likely number and timing of major impacts in the prehistory of the impactor indicates that a fully molten, undifferentiated condition for that relatively small body is unlikely. Given selective sampling by the giant impact, any significant vertical differentiation within the noncore portion of the impactor would have been largely inherited by the Moon.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, L.; Qian, S.-B.; Zhu, L.-Y.

The secured four-color light curves of VW Boo were analyzed with the 2003 version of the Wilson-Devinney code. It is confirmed that VW Boo is a shallow W-type contact binary system with a degree of contact factor f = 10.8%({+-} 0.5%). Two dark spots were found on the massive cool component this time. They cause an unequal depth of the two maxima. A period investigation based on all available visual, photographic, CCD, and photoelectric data shows that the period of the system includes a long-term decrease (dP/dt = -1.454 x 10{sup -7} days yr{sup -1}) and an oscillation (A{sub 3}more » = 0.0059 days; T{sub 3} = 25.96 years). These may be caused by mass transfer, angular momentum loss, and cyclic magnetic activity.« less

A compact magnetic bearing for gimballed momentum wheel

NASA Technical Reports Server (NTRS)

Yabu-Uchi, K.; Inoue, M.; Akishita, S.; Murakami, C.; Okamoto, O.

1983-01-01

A three axis controlled magnetic bearing and its application to a momentum wheel are described. The four divided stators provide a momentum wheel with high reliability, low weight, large angular momentum storage capacity, and gimbal control. Those characteristics are desirable for spacecraft attitude control.

Equilibrium properties of the Skylab CMG rotation law

NASA Technical Reports Server (NTRS)

Elrod, B. D.; Anderson, G. M.

1972-01-01

The equilibrium properties of the control moment gyroscopes of the Skylab are discussed. A rotation law is developed to produce gimbal rates which distribute the angular momentum contributions among the control moment gyroscopes to avoid gimbal stop encounters. The implications for gimbal angle management under various angular momentum situations are described. Conditions were obtained for the existence of equilibria and corresponding stability properties.

Effect of Meaning Making Approach on Students' Conceptual Understanding: An Examination of Angular Momentum Conservation

ERIC Educational Resources Information Center

Bostan Sarioglan, Ayberk; Kucukozer, Huseyin

2017-01-01

The aim of this study is to analyze the effect of meaning making based instruction regarding angular momentum conservation on the change of two 11th grade students' alternative ideas they have before instruction. Case study model is used in the research. Conceptual test (implemented before the instruction, right after the instruction and fifteen…

Spectral representation of the three-body Coulomb problem. I. Nonautoionizing doubly excited states of high angular momentum in helium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eiglsperger, Johannes; Piraux, Bernard; Madronero, Javier

2010-04-15

We investigate high-lying doubly excited nonautoionizing states of helium with total angular momentum L=1,2,...,9 with the help of a configuration interaction approach. We provide highly precise nonrelativistic energies of these states and discuss the properties of the wave functions with respect to the particle exchange operator.

Carter constant and angular momentum

NASA Astrophysics Data System (ADS)

Mukherjee, Sajal; Nayak, K. Rajesh

We investigate the Carter-like constant in the case of a particle moving in a nonrelativistic dipolar potential. This special case is a missing link between the Carter constant in stationary and axially symmetric spacetimes (SASS) such as Kerr solution and its possible Newtonian counterpart. We use this system to carry over the definition of angular momentum from the Newtonian mechanics to the relativistic SASS.

Control of Angular Momentum during Walking in Children with Cerebral Palsy

ERIC Educational Resources Information Center

Bruijn, Sjoerd M.; Meyns, Pieter; Jonkers, Ilse; Kaat, Desloovere; Duysens, Jacques

2011-01-01

Children with hemiparetic Cerebral Palsy (CP) walk with marked asymmetries. For instance, we have recently shown that they have less arm swing on the affected side, and more arm swing at the unaffected side. Such an increase in arm swing at the unaffected side may be aimed at controlling total body angular momentum about the vertical axis,…

Inequality between size and angular momentum for bodies.

PubMed

Dain, Sergio

2014-01-31

A universal inequality that bounds the angular momentum of a body by the square of its size is presented and heuristic physical arguments are given to support it. We prove a version of this inequality, as consequence of the Einstein equations, for the case of rotating axially symmetric, constant density, bodies. Finally, the physical relevance of this result is discussed.

Mass, angular momentum, and charge inequalities for black holes in Einstein-Maxwell-axion-dilaton gravity

NASA Astrophysics Data System (ADS)

Rogatko, Marek

2014-02-01

Mass, angular momentum, and charge inequalities for axisymmetric maximal time-symmetric initial data invariant under an action of U(1) group, in Einstein-Maxwell-axion-dilaton gravity being the low-energy limit of the heterotic string theory, is established. We assume that a data set with two asymptotically flat regions is given on a smooth simply connected manifold. We also pay attention to the area momentum charge inequalities for a closed orientable two-dimensional spacelike surface embedded in the spacetime of the considered theory.

A Potential Proxy of the Second Integral of Motion (I2) in a Rotating Barred Potential

NASA Astrophysics Data System (ADS)

Shen, Juntai; Qin, Yujing

2017-06-01

The only analytically known integral of motion in a 2-D rotating barred potential is the Jacobi constant (EJ). In addition to EJ, regular orbits also obey a second integral of motion (I2) whose analytical form is unknown. We show that the time-averaged characteristics of angular momentum in a rotating bar potential resemble the behavior of the analytically-unknown I2. For a given EJ, regular orbits of various families follow a continuous sequence in the space of net angular momentum and its dispersion ("angular momentum space"). In the limiting case where regular orbits of the well-known x1/x4 orbital families dominate the phase space, the orbital sequence can be monotonically traced by a single parameter, namely the ratio of mean angular momentum to its dispersion. This ratio behaves well even in the 3-D case, and thus may be used as a proxy of I2. The potential proxy of I2 may be used as an efficient way to probe the phase space structure, and a convenient new scheme of orbit classification in addition to the frequency mapping technique.

Mode-Division-Multiplexing of Multiple Bessel-Gaussian Beams Carrying Orbital-Angular-Momentum for Obstruction-Tolerant Free-Space Optical and Millimetre-Wave Communication Links.

PubMed

Ahmed, Nisar; Zhao, Zhe; Li, Long; Huang, Hao; Lavery, Martin P J; Liao, Peicheng; Yan, Yan; Wang, Zhe; Xie, Guodong; Ren, Yongxiong; Almaiman, Ahmed; Willner, Asher J; Ashrafi, Solyman; Molisch, Andreas F; Tur, Moshe; Willner, Alan E

2016-03-01

We experimentally investigate the potential of using 'self-healing' Bessel-Gaussian beams carrying orbital-angular-momentum to overcome limitations in obstructed free-space optical and 28-GHz millimetre-wave communication links. We multiplex and transmit two beams (l = +1 and +3) over 1.4 metres in both the optical and millimetre-wave domains. Each optical beam carried 50-Gbaud quadrature-phase-shift-keyed data, and each millimetre-wave beam carried 1-Gbaud 16-quadrature-amplitude-modulated data. In both types of links, opaque disks of different sizes are used to obstruct the beams at different transverse positions. We observe self-healing after the obstructions, and assess crosstalk and power penalty when data is transmitted. Moreover, we show that Bessel-Gaussian orbital-angular-momentum beams are more tolerant to obstructions than non-Bessel orbital-angular-momentum beams. For example, when obstructions that are 1 and 0.44 the size of the l = +1 beam, are placed at beam centre, optical and millimetre-wave Bessel-Gaussian beams show ~6 dB and ~8 dB reduction in crosstalk, respectively.

Mode-Division-Multiplexing of Multiple Bessel-Gaussian Beams Carrying Orbital-Angular-Momentum for Obstruction-Tolerant Free-Space Optical and Millimetre-Wave Communication Links

PubMed Central

Ahmed, Nisar; Zhao, Zhe; Li, Long; Huang, Hao; Lavery, Martin P. J.; Liao, Peicheng; Yan, Yan; Wang, Zhe; Xie, Guodong; Ren, Yongxiong; Almaiman, Ahmed; Willner, Asher J.; Ashrafi, Solyman; Molisch, Andreas F.; Tur, Moshe; Willner, Alan E.

2016-01-01

We experimentally investigate the potential of using ‘self-healing’ Bessel-Gaussian beams carrying orbital-angular-momentum to overcome limitations in obstructed free-space optical and 28-GHz millimetre-wave communication links. We multiplex and transmit two beams (l = +1 and +3) over 1.4 metres in both the optical and millimetre-wave domains. Each optical beam carried 50-Gbaud quadrature-phase-shift-keyed data, and each millimetre-wave beam carried 1-Gbaud 16-quadrature-amplitude-modulated data. In both types of links, opaque disks of different sizes are used to obstruct the beams at different transverse positions. We observe self-healing after the obstructions, and assess crosstalk and power penalty when data is transmitted. Moreover, we show that Bessel-Gaussian orbital-angular-momentum beams are more tolerant to obstructions than non-Bessel orbital-angular-momentum beams. For example, when obstructions that are 1 and 0.44 the size of the l = +1 beam, are placed at beam centre, optical and millimetre-wave Bessel-Gaussian beams show ~6 dB and ~8 dB reduction in crosstalk, respectively. PMID:26926068

Integral momenta of vortex Bessel-Gaussian beams in turbulent atmosphere.

PubMed

Lukin, Igor P

2016-04-20

The orbital angular momentum of vortex Bessel-Gaussian beams propagating in turbulent atmosphere is studied theoretically. The field of an optical beam is determined through the solution of the paraxial wave equation for a randomly inhomogeneous medium with fluctuations of the refraction index of the turbulent atmosphere. Peculiarities in the behavior of the total power of the vortex Bessel-Gaussian beam at the receiver (or transmitter) are examined. The dependence of the total power of the vortex Bessel-Gaussian beam on optical beam parameters, namely, the transverse wave number of optical radiation, amplitude factor radius, and, especially, topological charge of the optical beam, is analyzed in detail. It turns out that the mean value of the orbital angular momentum of the vortex Bessel-Gaussian beam remains constant during propagation in the turbulent atmosphere. It is shown that the variance of fluctuations of the orbital angular momentum of the vortex Bessel-Gaussian beam propagating in turbulent atmosphere calculated with the "mean-intensity" approximation is equal to zero identically. Thus, it is possible to declare confidently that the variance of fluctuations of the orbital angular momentum of the vortex Bessel-Gaussian beam in turbulent atmosphere is not very large.

On the role of surface friction in tropical cyclone intensification

NASA Astrophysics Data System (ADS)

Wang, Yuqing

2017-04-01

Recent studies have debated on whether surface friction is positive or negative to tropical cyclone intensification in the view on angular momentum budget. That means whether the frictionally induced inward angular momentum transport can overcome the loss of angular momentum to the surface due to surface friction itself. Although this issue is still under debate, this study investigates another implicit dynamical effect, which modifies the radial location and strength of eyewall convection. We found that moderate surface friction is necessary for rapid intensity of tropical cyclones. This is demonstrated first by a simple coupled dynamical system that couples a multi-level boundary layer model and a shallow water equation model above with mass source parameterized by mass flux from the boundary layer model below, and then by a full physics model. The results show that surface friction leads to the inward penetration of inflow under the eyewall, shift the boundary layer mass convergence slightly inside the radius of maximum wind, and enhance the upward mass flux, and thus diabatic heating in the eyewall and intensification rate of a TC. This intensification process is different from the direct angular momentum budget previously used to explain the role of surface friction in tropical cyclone intensification.

Role of angular momentum and cosmic censorship in (2+1)-dimensional rotating shell collapse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mann, Robert B.; Oh, John J.; Park, Mu-In

2009-03-15

We study the gravitational collapse problem of rotating shells in three-dimensional Einstein gravity with and without a cosmological constant. Taking the exterior and interior metrics to be those of stationary metrics with asymptotically constant curvature, we solve the equations of motion for the shells from the Darmois-Israel junction conditions in the corotating frame. We study various collapse scenarios with arbitrary angular momentum for a variety of geometric configurations, including anti-de Sitter, de Sitter, and flat spaces. We find that the collapsing shells can form a BTZ black hole, a three-dimensional Kerr-dS spacetime, and an horizonless geometry of point masses undermore » certain initial conditions. For pressureless dust shells, the curvature singularity is not formed due to the angular momentum barrier near the origin. However when the shell pressure is nonvanishing, we find that for all types of shells with polytropic-type equations of state (including the perfect fluid and the generalized Chaplygin gas), collapse to a naked singularity is possible under generic initial conditions. We conclude that in three dimensions angular momentum does not in general guard against violation of cosmic censorship.« less

Zero potential vorticity envelopes for the zonal-mean velocity of the Venus/Titan atmospheres

NASA Technical Reports Server (NTRS)

Allison, Michael; Del Genio, Anthony D.; Zhou, Wei

1994-01-01

The diagnostic analysis of numerical simulations of the Venus/Titan wind regime reveals an overlooked constraint upon the latitudinal structure of their zonal-mean angular momentum. The numerical experiments, as well as the limited planetary observations, are approximately consistent with the hypothesis that within the latitudes bounded by the wind maxima the total Ertel potential vorticity associated with the zonal-mean motion is approximately well mixed with respect to the neutral equatorial value for a stable circulation. The implied latitudinal profile of angular momentum is of the form M equal to or less than M(sub e)(cos lambda)(exp 2/Ri), where lambda is the latitude and Ri the local Richardson number, generally intermediate between the two extremes of uniform angular momentum (Ri approaches infinity) and uniform angular velocity (Ri = 1). The full range of angular momentum profile variation appears to be realized within the observed meridional - vertical structure of the Venus atmosphere, at least crudely approaching the implied relationship between stratification and zonal velocity there. While not itself indicative of a particular eddy mechanism or specific to atmospheric superrotation, the zero potential vorticity (ZPV) constraint represents a limiting bound for the eddy - mean flow adjustment of a neutrally stable baroclinic circulation and may be usefully applied to the diagnostic analysis of future remote sounding and in situ measurements from planetary spacecraft.

A rough end for smooth microstate geometries

DOE PAGES

Marolf, Donald; Michel, Ben; Puhm, Andrea

2017-05-03

Supersymmetric microstate geometries with five non-compact dimensions have recently been shown by Eperon, Reall, and Santos (ERS) to exhibit a non-linear instability featuring the growth of excitations at an “evanescent ergosurface” of infinite redshift. We argue that this growth may be treated as adiabatic evolution along a family of exactly supersymmetric solutions in the limit where the excitations are Aichelburg-Sexl-like shockwaves. In the 2-charge system such solutions may be constructed explicitly, incorpo-rating full backreaction, and are in fact special cases of known microstate geometries. In a near-horizon limit, they reduce to Aichelburg-Sexl shockwaves in AdS 3 × S 3 propagatingmore » along one of the angular directions of the sphere. Noting that the ERS analysis is valid in the limit of large microstate angular momentum j, we use the above identification to interpret their instability as a transition from rare smooth microstates with large angular momentum to more typical microstates with smaller angular momentum. This entropic driving terminates when the angular momentum decreases to j~√n 1n 5 where the density of microstates is maximal. Finally, we argue that, at this point, the large stringy corrections to such microstates will render them non-linearly stable. We identify a possible mechanism for this stabilization and detail an illustrative toy model.« less

Photometric Properties for Selected Algol-type Binaries. VIII. The Triple Systems DI Peg and AF Gem Revisited

NASA Astrophysics Data System (ADS)

Yang, Yuan-Gui; Yang, Ying; Li, Shu-Zheng

2014-06-01

New extensive photometry for two triple binary stars, DI Peg and AF Gem, was performed from 2012 October to 2013 January, with two small telescopes at Xinglong station (XLs) of NAOC. From new multi-color observations and previously published ones in literature, the photometric models were (re)deduced using the updated Wilson-Devinney code. The results indicated that the low third lights exist in two classic Algol-type binaries, whose fill-out factors for the more massive components are fp = 78.2(± 0.4)% for DI Peg, and fp = 69.0(± 0.3)% for AF Gem, respectively. Through analyzing the O-C curves, the orbital periods for two binaries change in the complicated mode. The period of DI Peg possibly appears to show two light-time orbits, whose modulated periods are P 3 = 54.6(± 0.5) yr and P 4 = 23.0(± 0.6) yr, respectively. The inferred minimum masses for the inner and outer sub-stellar companions are M in = 0.095 M ⊙ and M out = 0.170 M ⊙, respectively. Therefore, DI Peg may be a quadruple star. The orbital period of AF Gem appears to show a continuous period decrease or a cyclic variation; the latter may be preferable. The cyclic oscillation, with a period of 120.3(± 2.5) yr, may be attributed to the light-time effect due to the third body. This kind of additional companion may extract angular momentum from the central system, which may play a key role in the evolution of the binary.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Y.-G.; Dai, H.-F.; Zhang, X.-B.

We present new photometry for the eclipsing binary V1241 Tau, which was obtained on six nights between 2011 December and 2012 January using the 85 cm telescope at the Xinglong station of the National Astronomical Observatories of China. By using the updated Wilson-Devinney code, photometric models with third lights were deduced from two sets of light curves. The result implies that V1241 Tau is an Algol-type near-contact binary (NCB), whose mass ratio and filling-out of the primary are q = 0.545 ({+-} 0.003) and f{sub 1} = 82.4% ({+-} 0.2%), respectively. Based on all available times of minimum light spanningmore » over 80 yr, the O - C curve of V1241 Tau appears to show a quasi-sinusoidal oscillation, i.e., a light-time orbit. The modulated period and amplitude are P{sub mod} = 47.4 ({+-} 1.7) yr and A = 0.0087 ({+-} 0.0005) days, respectively. This kind of period variation may be more likely attributed to the light-time effect via a presence of an unseen third body. From an analysis of 23 Algol-type NCBs with EB-type light curves, we determine that the fill-out for the primary f{sub 1} will increase as the orbital period P decreases. With angular momentum loss, the orbit of the binary will shrink, which causes f{sub 1} to increase. The primary component finally fills its Roche lobe, and the binary evolves into contact configuration. Therefore, this kind of Algol-type NCB with EB-type light curves, such as V1241 Tau, may be a progenitor of the A-type W UMa binary.« less

Measuring the spin of black holes in binary systems using gravitational waves.

PubMed

Vitale, Salvatore; Lynch, Ryan; Veitch, John; Raymond, Vivien; Sturani, Riccardo

2014-06-27

Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground-based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions and the opportunity of measuring spins directly through GW observations. In this Letter, we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientations, and signal-to-noise ratios, as detected by an advanced LIGO-Virgo network. We find that for moderate or high signal-to-noise ratio the spin magnitudes can be estimated with errors of a few percent (5%-30%) for neutron star-black hole (black hole-black hole) systems. Spins' tilt angle can be estimated with errors of 0.04 rad in the best cases, but typical values will be above 0.1 rad. Errors will be larger for signals barely above the threshold for detection. The difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum and that a sudden change of behavior occurs when a system is observed from angles such that the plane of the orbit can be seen both from above and below during the time the signal is in band. This study suggests that direct measurement of black hole spin by means of GWs can be as precise as what can be obtained from x-ray binaries.

Spin memory effect for compact binaries in the post-Newtonian approximation

NASA Astrophysics Data System (ADS)

Nichols, David A.

2017-04-01

The spin memory effect is a recently predicted relativistic phenomenon in asymptotically flat spacetimes that become nonradiative infinitely far in the past and future. Between these early and late times, the magnetic-parity part of the time integral of the gravitational-wave strain can undergo a nonzero change; this difference is the spin memory effect. Families of freely falling observers around an isolated source can measure this effect, in principle, and fluxes of angular momentum per unit solid angle (or changes in superspin charges) generate the effect. The spin memory effect had not been computed explicitly for astrophysical sources of gravitational waves, such as compact binaries. In this paper, we compute the spin memory in terms of a set of radiative multipole moments of the gravitational-wave strain. The result of this calculation allows us to establish the following results about the spin memory: (i) We find that the accumulation of the spin memory behaves in a qualitatively different way from that of the displacement memory effect for nonspinning, quasicircular compact binaries in the post-Newtonian approximation: the spin memory undergoes a large secular growth over the duration of the inspiral, whereas for the displacement effect this increase is small. (ii) The rate at which the spin memory grows is equivalent to a nonlinear, but nonoscillatory and nonhereditary effect in the gravitational waveform that had been previously calculated for nonspinning, quasicircular compact binaries. (iii) This rate of buildup of the spin memory could potentially be detected by future gravitational-wave detectors by carefully combining the measured waveforms from hundreds of gravitational-wave detections of compact binaries.

FORMATION AND EVOLUTION OF GALACTIC INTERMEDIATE/LOW-MASS X-RAY BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shao, Yong; Li, Xiang-Dong, E-mail: lixd@nju.edu.cn

2015-08-10

We investigate the formation and evolutionary sequences of Galactic intermediate- and low-mass X-ray binaries (I/LMXBs) by combining binary population synthesis (BPS) and detailed stellar evolutionary calculations. Using an updated BPS code we compute the evolution of massive binaries that leads to the formation of incipient I/LMXBs and present their distribution in the initial donor mass versus initial orbital period diagram. We then follow the evolution of the I/LMXBs until the formation of binary millisecond pulsars (BMSPs). We find that the birthrate of the I/LMXB population is in the range of 9 × 10{sup −6}–3.4 × 10{sup −5} yr{sup −1}, compatiblemore » with that of BMSPs that are thought to descend from I/LMXBs. We show that during the evolution of I/LMXBs they are likely to be observed as relatively compact binaries with orbital periods ≲1 day and donor masses ≲0.3M{sub ⊙}. The resultant BMSPs have orbital periods ranging from less than 1 day to a few hundred days. These features are consistent with observations of LMXBs and BMSPs. We also confirm the discrepancies between theoretical predictions and observations mentioned in the literature, that is, the theoretical average mass transfer rates (∼10{sup −10} M{sub ⊙} yr{sup −1}) of LMXBs are considerably lower than observed, and the number of BMSPs with orbital periods ∼0.1–10 days is severely underestimated. These discrepancies imply that something is missing in the modeling of LMXBs, which is likely to be related to the mechanisms of the orbital angular momentum loss.« less

POET: Planetary Orbital Evolution due to Tides

NASA Astrophysics Data System (ADS)

Penev, Kaloyan

2014-08-01

POET (Planetary Orbital Evolution due to Tides) calculates the orbital evolution of a system consisting of a single star with a single planet in orbit under the influence of tides. The following effects are The evolutions of the semimajor axis of the orbit due to the tidal dissipation in the star and the angular momentum of the stellar convective envelope by the tidal coupling are taken into account. In addition, the evolution includes the transfer of angular momentum between the stellar convective and radiative zones, effect of the stellar evolution on the tidal dissipation efficiency, and stellar core and envelope spins and loss of stellar convective zone angular momentum to a magnetically launched wind. POET can be used out of the box, and can also be extended and modified.

The Sub-bureau for Atmospheric Angular Momentum of the International Earth Rotation Service - A meteorological data center with geodetic applications

NASA Technical Reports Server (NTRS)

Salstein, David A.; Kann, Deirdre M.; Miller, Alvin J.; Rosen, Richard D.

1993-01-01

By exchanging angular momentum with the solid portion of the earth, the atmosphere plays a vital role in exciting small but measurable changes in the rotation of our planet. Recognizing this relationship, the International Earth Rotation Service invited the U.S. National Meteorological Center to organize a Sub-bureau for Atmospheric Angular Momentum (SBAAM) for the purpose of collecting, distributing, archiving, and analyzing atmospheric parameters relevant to earth rotation/polar motion. These functions of wind and surface pressure are being computed with data from several of the world's weather services, and they are being widely applied to the research and operations of the geodetic community. The SBAAM began operating formally in October 1989, and this article highlights its development, operations, and significance.

Null Angular Momentum and Weak KAM Solutions of the Newtonian N-Body Problem

NASA Astrophysics Data System (ADS)

Percino-Figueroa, Boris A.

2017-08-01

In [Arch. Ration. Mech. Anal. 213 (2014), 981-991] it has been proved that in the Newtonian N-body problem, given a minimal central configuration a and an arbitrary configuration x, there exists a completely parabolic orbit starting on x and asymptotic to the homothetic parabolic motion of a, furthermore such an orbit is a free time minimizer of the action functional. In this article we extend this result in abundance of completely parabolic motions by proving that under the same hypothesis it is possible to get that the completely parabolic motion starting at x has zero angular momentum. We achieve this by characterizing the rotation invariant weak KAM solutions as those defining a lamination on the configuration space by free time minimizers with zero angular momentum.

Energy and angular momentum balance in wall-bounded quantum turbulence at very low temperatures.

PubMed

Hosio, J J; Eltsov, V B; Heikkinen, P J; Hänninen, R; Krusius, M; L'vov, V S

2013-01-01

A superfluid in the absence of a viscous normal component should be the best realization of an ideal inviscid Euler fluid. As expressed by d'Alembert's famous paradox, an ideal fluid does not drag on bodies past which it flows, or in other words it does not exchange momentum with them. In addition, the flow of an ideal fluid does not dissipate kinetic energy. Here we study experimentally whether these properties apply to the flow of superfluid (3)He-B in a rotating cylinder at low temperatures. It is found that ideal behaviour is broken by quantum turbulence, which leads to substantial energy dissipation, as was also observed earlier. Remarkably, the angular momentum exchange between the superfluid and its container approaches nearly ideal behaviour, as the drag almost disappears in the zero-temperature limit. Here the mismatch between energy and angular momentum transfer results in a new physical situation, with severe implications on the flow dynamics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murguia-Berthier, Ariadna; Ramirez-Ruiz, Enrico; Antoni, Andrea

During a common envelope (CE) episode in a binary system, the engulfed companion spirals to tighter orbital separations under the influence of drag from the surrounding envelope material. As this object sweeps through material with a steep radial gradient of density, net angular momentum is introduced into the flow, potentially leading to the formation of an accretion disk. The presence of a disk would have dramatic consequences for the outcome of the interaction because accretion might be accompanied by strong, polar outflows with enough energy to unbind the entire envelope. Without a detailed understanding of the necessary conditions for diskmore » formation during CE, therefore, it is difficult to accurately predict the population of merging compact binaries. This paper examines the conditions for disk formation around objects embedded within CEs using the “wind tunnel” formalism developed by MacLeod et al. We find that the formation of disks is highly dependent on the compressibility of the envelope material. Disks form only in the most compressible of stellar envelope gas, found in envelopes’ outer layers in zones of partial ionization. These zones are largest in low-mass stellar envelopes, but comprise small portions of the envelope mass and radius in all cases. We conclude that disk formation and associated accretion feedback in CE is rare, and if it occurs, transitory. The implication for LIGO black hole binary assembly is that by avoiding strong accretion feedback, CE interactions should still result in the substantial orbital tightening needed to produce merging binaries.« less

The Near-contact Binary RZ Draconis with Two Possible Light-time Orbits

NASA Astrophysics Data System (ADS)

Yang, Y.-G.; Li, H.-L.; Dai, H.-F.; Zhang, L.-Y.

2010-12-01

We present new multicolor photometry for RZ Draconis, observed in 2009 at the Xinglong Station of the National Astronomical Observatories of China. By using the updated version of the Wilson-Devinney Code, the photometric-spectroscopic elements were deduced from new photometric observations and published radial velocity data. The mass ratio and orbital inclination are q = 0.375(±0.002) and i = 84fdg60(±0fdg13), respectively. The fill-out factor of the primary is f = 98.3%, implying that RZ Dra is an Algol-like near-contact binary. Based on 683 light minimum times from 1907 to 2009, the orbital period change was investigated in detail. From the O - C curve, it is discovered that two quasi-sinusoidal variations may exist (i.e., P 3 = 75.62(±2.20) yr and P 4 = 27.59(±0.10) yr), which likely result from light-time effects via the presence of two additional bodies. In a coplanar orbit with the binary system, the third and fourth bodies may be low-mass drafts (i.e., M 3 = 0.175 M sun and M 4 = 0.074 M sun). If this is true, RZ Dra may be a quadruple star. The additional body could extract angular momentum from the binary system, which may cause the orbit to shrink. With the orbit shrinking, the primary may fill its Roche lobe and RZ Dra evolves into a contact configuration.