IBEX Ribbon Separation Using Spherical Harmonic Decomposition of the Globally Distributed Flux

Remote imaging of plasmas in the heliosphere and very local interstellar medium is possible with energetic neutral atoms (ENAs), created through the charge exchange of protons with interstellar neutral atoms. ENA observations collected by the Interstellar Boundary Explorer (IBEX) revealed two distinctive sources. One source is the globally distributed flux (GDF), which extends over the entire sky and varies over large spatial scales. The other source encompasses only a narrow circular band in the sky and is called the IBEX ribbon. Here, we utilize the observed difference in spatial scales of these two ENA sources to separate them. We find that linear combinations of spherical harmonics up to degree ℓ max = 3 can reproduce most of the ENA fluxes observed outside the ribbon region. We use these combinations to model the GDF and the difference between the observed fluxes and the GDF yields estimation of the ribbon emission. The separated ribbon responds with a longer time delay to the solar wind changes than the GDF, suggesting a more distant source of the ribbon ENAs. Moreover, we locate the direction of the maximum plasma pressure based on the GDF. This direction is 17°.2 ± 0°.5 away from the upwind direction within the plane containing the interstellar flow and interstellar magnetic field vectors. This deflection is consistent with the expected position of the maximum external pressure at the heliopause. The maps with separated ribbon and GDF are posted concurrently with this paper and can be used to further study these two sources.

New insights on the massive interacting binary UU Cassiopeiae

We present the results of our study of the close binary UU Cassiopeiae based on previously published multiwavelength photometric and spectroscopic data. Based on eclipse timings from the last 117 years, we find an improved orbital period of Po = 8.d519296(8). In addition, we find a long cycle of length T ∼ 270 d in the Ic-band data. There is no evidence for orbital period change over the last century, suggesting that the rate of mass loss from the system or mass exchange between the stars is small. Sporadic and rapid brightness drops of up to ΔV = 0.3 mag are detected throughout the orbital cycle, and infrared photometry clearly suggests the presence of circumstellar matter. We model the orbital light curve of 11 published datasets, fixing the mass ratio and cooler star temperature from previous spectroscopic work: q = 0.52 and Tc = 22 700 K. We find a system seen at an angle of 74° with a stellar separation of 52 R⊙, a temperature for the hotter star of Th = 30 200 K and, for the hotter and cooler stars, respectively, stellar masses of 17.4 and 9 M⊙, radii of 7.0 and 16.9 R⊙, and surface gravities log g = 3.98 and 2.94. We find an accretion disk surrounding the more massive star that has a radius of 21 R⊙ and a vertical thickness at its outer edge of 6.5 R⊙; the disk nearly occults the hotter star. Two active regions hotter than the surrounding disk are found, one located roughly in the expected position where the stream impacts the disk and the other on the opposite side of the disk. Changes are observed in parameters of the disk and spots in different datasets.

Asymptotic generalized extended uncertainty principle

We present a formalism which allows for the perturbative derivation of the Extended Uncertainty Principle (EUP) for arbitrary spatial curvature models and observers. Entering the realm of small position uncertainties, we derive a general asymptotic EUP. The leading 2nd order curvature induced correction is proportional to the Ricci scalar, while the 4th order correction features the 0th order Cartan invariant $$\Psi _2$$Ψ2 (a scalar quadratic in curvature tensors) and the curved space Laplacian of the Ricci scalar all of which are evaluated at the expectation value of the position operator i.e. the expected position when performing a measurement. This result is first verified for previously derived homogeneous space models and then applied to other non-trivial curvature related effects such as inhomogeneities, rotation and an anisotropic stress fluid leading to black hole “hair”. Our main achievement combines the method we introduce with the Generalized Uncertainty Principle (GUP) by virtue of deformed commutators to formulate a generic form of what we call the Asymptotic Generalized Extended Uncertainty Principle (AGEUP).

Asymmetric distributions of H2O and SiO masers towards V627 Cas

ABSTRACT We performed simultaneous observations of the $\rm H_2O$ 61,6 − 52,3 (22.235080 GHz) and SiO v = 1, 2, J = 1 → 0, SiO v = 1, J = 2 → 1, 3 → 2 (43.122080, 42.820587, 86.243442, and 129.363359 GHz) masers towards the suspected D-type symbiotic star, V627 Cas, using the Korean VLBI Network. Here, we present astrometrically registered maps of the $\rm H_2O$ and SiO v = 1, 2, J = 1 → 0, SiO v = 1, J = 2 → 1 masers for five epochs from January 2016 to June 2018. Distributions of the SiO maser spots do not show clear ring-like structures, and those of the $\rm H_2O$ maser are biased towards the north–north-west to west with respect to the SiO maser features according to observational epochs. These asymmetric distributions of $\rm H_2O$ and SiO masers are discussed based on two scenarios of a bipolar outflow and the presence of the hot companion, a white dwarf, in V627 Cas. We carried out ring fitting of SiO v = 1, and v = 2 masers and estimated the expected position of the cool red giant. The ring radii of the SiO v = 1 maser are slightly larger than those of the SiO v = 2 maser, as previously known. Our assumption for the physical size of the SiO maser ring of V627 Cas to be the typical size of a SiO maser ring radius (∼4 au) of red giants yields the distance of V627 Cas to be ∼1 kpc.

The Brightest Point in Accretion Disk and Black Hole Spin: Implication to the Image of Black Hole M87*

We propose the simple new method for extracting the value of the black hole spin from the direct high-resolution image of black hole by using a thin accretion disk model. In this model, the observed dark region on the first image of the supermassive black hole in the galaxy M87, obtained by the Event Horizon Telescope, is a silhouette of the black hole event horizon. The outline of this silhouette is the equator of the event horizon sphere. The dark silhouette of the black hole event horizon is placed within the expected position of the black hole shadow, which is not revealed on the first image. We calculated numerically the relation between the observed position of the black hole silhouette and the brightest point in the thin accretion disk, depending on the black hole spin. From this relation, we derive the spin of the supermassive black hole M87*, a = 0.75 ± 0.15 .

A large rotating structure around AB Doradus A at VLBI scale

We report the results of three VLBI observations of the pre-main-sequence star AB Doradus A at 8.4 GHz. With almost three years between consecutive observations, we found a complex structure at the expected position of this star for all epochs. Maps at epochs 2007 and 2010 show a double core-halo morphology while the 2013 map reveals three emission peaks with separations between 5 and 18 stellar radii. Furthermore, all maps show a clear variation of the source structure within the observing time. We consider a number of hypothesis in order to explain such observations, mainly: magnetic reconnection in loops on the polar cap, a more general loop scenario and a close companion to AB Dor A.

The Death Throes of Sacrificed Chicken

In Kabye society, the commonest sacrificial rites include a device that may prompt celebrants to question their own ritual practice. As in other West African societies, the acceptance or refusal of an offering by a divinity is read in the death throes of the first chicken to be sacrificed. If the fowl does not die in the expected position, the ceremony is interrupted. Celebrants scrutinize the execution of the rite to identify the mistake that led to the sacrifice’s refusal, and they submit their hypothesis to the divinity. However, the resumption of the rite is not conditioned by the correction of the mistake. It is often sufficient that officiants recognize and reassert the rule that they should have followed. The case of a bull sacrifice demonstrates how the celebrants’ self-critical practice may promote a ritual effectiveness in connection with the dialogical and pragmatic nature of the rite.

Rethinking Mass and Elite: Decision-Making in the Athenian Law-Courts

This chapter puts pressure on the ‘mass and elite model’ of Athenian litigation introduced by Ober. According to this framework, litigation is a game played by elite litigants and mass audiences; the ‘masses’ constitute a monolithic body with identical preferences; the ‘elites’ are thoroughly aware of, and willingly play by, the rules set by the masses. Moving from a different interpretation of Athenian political sociology, this chapter builds a new model of Athenian litigation that modifies Ober’s in three important respects: first, the jurors’ preferences are not the product of a monolithic and static ‘mass’ ideology; second, litigants (not only elites) can reasonably predict the location of the median juror; and third, litigants’ arguments are the product of a cost‐benefit analysis that depends a) on the relative expected position of their opponent; b) on the expected position of the median juror; and c) on the policy/legal agenda they are pursuing. The model proposed here suggests that repeated interactions in the law‐courts allowed diverse interests to be advanced and negotiated, which helped the Athenians collectively define the boundaries of their social relations while responding to the new challenges that a post‐imperial, highly fragmented Greek ecology posed to Athens’ stability and prosperity.

Cooperative Virtual Sensor for Fault Detection and Identification in Multi-UAV Applications

This paper considers the problem of fault detection and identification (FDI) in applications carried out by a group of unmanned aerial vehicles (UAVs) with visual cameras. In many cases, the UAVs have cameras mounted onboard for other applications, and these cameras can be used as bearing-only sensors to estimate the relative orientation of another UAV. The idea is to exploit the redundant information provided by these sensors onboard each of the UAVs to increase safety and reliability, detecting faults on UAV internal sensors that cannot be detected by the UAVs themselves. Fault detection is based on the generation of residuals which compare the expected position of a UAV, considered as target, with the measurements taken by one or more UAVs acting as observers that are tracking the target UAV with their cameras. Depending on the available number of observers and the way they are used, a set of strategies and policies for fault detection are defined. When the target UAV is being visually tracked by two or more observers, it is possible to obtain an estimation of its 3D position that could replace damaged sensors. Accuracy and reliability of this vision-based cooperative virtual sensor (CVS) have been evaluated experimentally in a multivehicle indoor testbed with quadrotors, injecting faults on data to validate the proposed fault detection methods.

Effects of Auditory Patterns on Judged Displacements of an Occluded Moving Object

Using displays in which a moving disk disappeared behind an occluder, we examined whether an accompanying auditory rhythm influenced the perceived displacement of the disk during occlusion. We manipulated a baseline rhythm, comprising a relatively fast alternation of equal sound and pause durations. We had two different manipulations to create auditory sequences with a slower rhythm: either the pause durations or the sound durations were increased. In the trial, a disk moved at a constant speed, and at a certain point moved behind an occluder during which an auditory rhythm was played. Participants were instructed to track the occluded disk, and judge the expected position of the disk at the moment that the auditory rhythm ended by touching the judged position on a touch screen. We investigated the influence of the auditory rhythm, i.e., ratio of sound to pause duration, and the influence of auditory density, i.e., the number of sound onsets per time unit, on the judged distance. The results showed that the temporal characteristics affected the spatial judgments. Overall, we found that in the current paradigm relatively slow rhythms led to shorter judged distance as compared to relatively fast rhythms for both pause and sound variations. There was no main effect of auditory density on the judged distance of an expected visual event. That is, whereas the speed of the auditory rhythm appears crucial, the number of sound onsets per time unit as such, i.e., the auditory density, appears a much weaker factor.