Search For Holes Research Articles

Evaporating primordial black holes in gamma ray and neutrino telescopes

A primordial black hole in the last stages of evaporation and located in the local neighborhood can produce a detectable signal in gamma ray and neutrino telescopes. We re-evaluate the expected gamma ray and neutrino fluxes from these transient point events and discuss the consequences for existing constraints. For gamma rays we improve the current bounds by a factor of few, while for neutrinos we obtain significantly different results than the existing literature. The capability and advantages of neutrino telescopes in the search for primordial black holes is discussed thoroughly. The correlations of gamma ray and neutrino energy and time profiles will be promoted as a powerful tool in identifying the primordial black holes, in case of detection.

Classification of imagined geometric shapes using EEG signals and convolutional neural networks

Brain-Computer interface systems allow the recognition of neuronal activity to create a direct communication channel between the brain and the outside world without using the peripheral nervous system. Many of the paradigms used are based on the detection of motor imagery and evoked potentials. In this work we study the use of visual imagery of geometric shapes to build a non-invasive BCI using convolutional neural networks and the black hole search algorithm. Our algorithm computes, for seven people, an average of 35% correctly when classifying 7 geometric shapes, and 70% when classifying the best two ones (line and parallelogram). The same technique has been tested on a set of data collected on eleven subjects when classifying 2 geometric shapes, and a maximum accuracy of 82% was obtained.

Kinesthetic Sensing for Peg-In-Hole Assembly Based on In-Hand Manipulation

This study proposes a new way of estimating the hole direction to reduce the search time deviation in peg-in-hole assembly. To perform a peg-in-hole assembly, the hole position has to be found. In our previous studies, we found the hole using a blind search method. The blind search method moves the peg in a predefined path until it finds the hole. However, using blind search, it is difficult to predict the peg-in-hole assembly completion time because hole position search time is different each time. This is because the peg moves along the same predefined path without considering the hole direction. Furthermore, if the direction of the hole is known, the hole search time deviation can be reduced compared to when the direction of the hole is not known at all. Therefore, we propose a new way of finding the hole direction using in-hand manipulation based on ‘kinesthetic sensing’. Additionally, we introduce the concept of ‘Free-Finger’ for in-hand manipulation. The proposed method uses fingers to find the hole direction and perform the peg-in-hole assembly. Hence, we can implement peg-in-hole assembly regardless of the performance of the manipulator. The feasibility of the proposed method was verified through experiments using a three-fingered gripper.

Quantum Legacies: Dispatches from an Uncertain World

Quantum Legacies: Dispatches from an Uncertain World

Local Active Galactic Nuclei with Large Broad-Hα Variability Reside in Red Galaxies

Abstract Inspired by our serendipitous discovery of six active galactic nuclei (AGNs) with varying broad-Hα fluxes over years from our search for intermediate-mass black holes (IMBHs), we conduct a systematic investigation of changing-look (CL) and large-variability AGNs. We collect all the CL AGNs at z < 0.15 and the reverberation-mapped AGNs with strongly variable broad Hα and perform careful decomposition fittings to both their images and spectra. We find two observational facts: (1) The host galaxies of local CL and large-variability AGNs, mainly being Seyferts, are in the red (gas-poor) tail of the general Seyfert galaxy population. (2) In contrast, there is a significant trend that their more luminous counterparts, namely CL and extremely variable quasars (CLQs and EVQs), are different: CLQs are generally in blue galaxies; in terms of the diagram of star formation rate and M *, local CL Seyfert galaxies are located in the green valley, whereas CLQ hosts are in the star-forming main sequence. We propose explanations for those strongly variable Seyferts and quasars, respectively, under the assumption that accretion disks broadly depend on nuclear fueling modes. Local large-variability and CL Seyferts are in nuclear famine mode, where cold-gas clumps can be formed stochastically in the fueling flow, and their episodic infall produces sharp peaks in the accretion-rate curve. CLQs and EVQs are in feast fueling mode, which may account for both their preference for blue galaxies and their variability pattern (high-amplitude tail of the continuous distribution). Lastly, we propose a new thinking: to search for IMBHs by optical variability in red galaxies.

Astrophysics and cosmology with a decihertz gravitational-wave detector: TianGO

We present the astrophysical science case for a space-based, decihertz gravitational-wave (GW) detector. We particularly highlight an ability to infer a source's sky location, both when combined with a network of ground-based detectors to form a long triangulation baseline, and by itself for the early warning of merger events. Such an accurate location measurement is the key for using GW signals as standard sirens for constraining the Hubble constant. This kind of detector also opens up the possibility to test type Ia supernovae progenitor hypotheses by constraining the merger rates of white dwarf binaries with both super- and sub-Chandrasekhar masses separately. We will discuss other scientific outcomes that can be delivered, including the constraint of structure formation in the early Universe, the search for intermediate-mass black holes, the precise determination of black hole spins, the probe of binary systems' orbital eccentricity evolution, and the detection of tertiary masses around merging binaries.

Learning, Improving, and Generalizing Motor Skills for the Peg-in-Hole Tasks Based on Imitation Learning and Self-Learning

We propose a framework based on imitation learning and self-learning to enable robots to learn, improve, and generalize motor skills. The peg-in-hole task is important in manufacturing assembly work. Two motor skills for the peg-in-hole task are targeted: “hole search” and “peg insertion”. The robots learn initial motor skills from human demonstrations and then improve and/or generalize them through reinforcement learning (RL). An initial motor skill is represented as a concatenation of the parameters of a hidden Markov model (HMM) and a dynamic movement primitive (DMP) to classify input signals and generate motion trajectories. Reactions are classified as familiar or unfamiliar (i.e., modeled or not modeled), and initial motor skills are improved to solve familiar reactions and generalized to solve unfamiliar reactions. The proposed framework includes processes, algorithms, and reward functions that can be used for various motor skill types. To evaluate our framework, the motor skills were performed using an actual robotic arm and two reward functions for RL. To verify the learning and improving/generalizing processes, we successfully applied our framework to different shapes of pegs and holes. Moreover, the execution time steps and path optimization of RL were evaluated experimentally.

Introducing the Search for Intermediate-mass Black Holes in Nearby Galaxies (SIBLING) Survey

Abstract Intermediate-mass black holes (IMBHs) have masses between 102 and 106 M ⊙ and are key to our understanding of the formation of massive black holes. The known population of IMBHs remains small, with a few hundred candidates and only a handful of them confirmed as bona fide IMBHs. Until now, the most widely used selection method is based on spectral analysis. Here we present a methodology to select IMBH candidates via optical variability analysis of the nuclear region of local galaxies ( ). Active IMBHs accreting at low rates show small amplitude variability with timescales of hours, as is seen in one of the known IMBHs, NGC 4395. We found a sample of ∼500 galaxies demonstrating fast and small amplitude variation in their week-based light curves. We estimate an average occupancy fraction of 4% and a surface density of ∼3 deg−2, which represent an increase by a factor of ∼40 compared to previous searches. A large fraction (78%) of the candidates are in spiral galaxies. We preliminarily confirm the active galactic nucleus nature of 22 sources via Baldwin, Phillips, and Terlevich diagrams using Sloan Digital Sky Survey legacy spectra. Further confirmation of these candidates will require multiwavelength observations, especially in X-ray and radio bands.

Search for binary black holes in 10 years of Fermi LAT data with information field theory

AbstractBlazars are powered by super-massive black holes at their centers and are known for extreme variability on timescales from minutes to years. In case of a binary black hole system, this duality is traceable as periodic modulation of their MeV to GeV emission. So far, no high-significance periodicity has been found with standard approaches. We developed a method to search for periodic patterns in Fermi/LAT light curves, using information field theory (IFT). IFT is a formulation of Bayesian statistics in terms of fields. Bayesian statistics is ideal for the problem at hand since the data is incomplete, irregularly sampled and obeys non-Gaussian statistics such that common least-squares methods do not apply. We present a proof of principle of this method, analyzing a sample of promising binary black hole candidates like PG 1553 + 113 and Mrk 501.

Search for black holes and sphalerons in high-multiplicity final states in proton-proton collisions at sqrt{s}=13 TeV

A search in energetic, high-multiplicity final states for evidence of physics beyond the standard model, such as black holes, string balls, and electroweak sphalerons, is presented. The data sample corresponds to an integrated luminosity of 35.9 fb−1 collected with the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV in 2016. Standard model backgrounds, dominated by multijet production, are determined from control regions in data without any reliance on simulation. No evidence for excesses above the predicted background is observed. Model-independent 95% confidence level upper limits on the cross section of beyond the standard model signals in these final states are set and further interpreted in terms of limits on semiclassical black hole, string ball, and sphaleron production. In the context of models with large extra dimensions, semiclassical black holes with minimum masses as high as 10.1 TeV and string balls with masses as high as 9.5 TeV are excluded by this search. Results of the first dedicated search for electroweak sphalerons are presented. An upper limit of 0.021 is set at 95% confidence level on the fraction of all quark-quark interactions above the nominal threshold energy of 9 TeV resulting in the sphaleron transition.

Decoding imagined upper limb movements using spectral features from high-density EEG

Brain-Computer interface systems allow the recognition of neuronal activity to create a direct communication channel between the brain and the outside world without using the peripheral nervous system. Many of the paradigms used are based on the detection of motor imagery and evoked potentials. In this work we study the use of visual imagery of geometric shapes to build a non-invasive BCI using convolutional neural networks and the black hole search algorithm. Our algorithm computes, for seven people, an average of 35% correctly when classifying 7 geometric shapes, and 70% when classifying the best two ones (line and parallelogram). The same technique has been tested on a set of data collected on eleven subjects when classifying 2 geometric shapes, and a maximum accuracy of 82% was obtained.

Method for Constructing Optimal Dark Coverings

The problem of constructing metric e-nets and corresponding coverings by balls for compact sets with a probability measure is considered. In the case of sets having metrically significant parts with a small measure (dark sets), methods for constructing e-nets are combined with the deep holes method in a unified approach. According to this approach, a constructed metric net is supplemented with its deep hole (the most distant element of the set) until the required accuracy is achieved. An existing implementation of the method for a metric set with a given probability measure is based on a pure global search for deep holes. To construct dark coverings, the method is implemented on the basis of a random multistart. For the resulting nets, the logarithm of the number of their elements is shown to be close to e-entropy, which means that they are optimal. Techniques for estimating the reliability and completeness of constructed (e, δ)-coverings in the sense of C.E. Shannon are described. The methods under consideration can be used to construct coverings of implicitly given sets with a measure defined on the preimage and to recover compact supports of multidimensional random variables with an unknown distribution law.

The effect of stellar-mass black holes on the central kinematics of ω Cen: a cautionary tale for IMBH interpretations

The search for intermediate-mass black holes (IMBHs) in the centre of globular clusters is often based on the observation of a central cusp in the surface brightness profile and a rise towards the centre in the velocity dispersion profiles. Similar signatures, however, could result from other effects, that need to be taken into account in order to determine the presence (or the absence) of an IMBH in these stellar systems. Following our previous exploration of the role of radial anisotropy in shaping these observational signatures, we analyse here the effects produced by the presence of a population of centrally concentrated stellar-mass black holes. We fit dynamical models to omega Cen data, and we show that models with ~5% of their mass in black holes (consistent with ~100% retention fraction after natal kicks) can reproduce the data. When simultaneously considering both radial anisotropy and mass segregation, the best-fit model includes a smaller population of remnants, and a less extreme degree of anisotropy with respect to the models that include only one of these features. These results underline that before conclusions about putative IMBHs can be made, the effects of stellar-mass black holes and radial anisotropy need to be properly accounted for.

Noncommutative Black Holes at the LHC

Based on the latest public results, 13 TeV data from the Large Hadron Collider at CERN has not indicated any evidence of hitherto tested models of quantum black holes, semiclassical black holes, or string balls. Such models have predicted signatures of particles with high transverse momenta. Noncommutative black holes remain an untested model of TeV-scale gravity that offers the starkly different signature of particles with relatively low transverse momenta. Considerations for a search for charged noncommutative black holes using the ATLAS detector will be discussed.

Search for black holes and other new phenomena in high-multiplicity final states in proton–proton collisions at [formula omitted

A search for new physics in energetic, high-multiplicity final states has been performed using proton–proton collision data collected with the CMS detector at a center-of-mass energy of 13TeV and corresponding to an integrated luminosity of 2.3fb−1. The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassical black holes and string balls with masses as high as 9.5TeV, and quantum black holes with masses as high as 9.0TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8TeV with the LHC Run 1 data.

AUTOMATED DETECTION AND CLOSING OF HOLES IN AERIAL POINT CLOUDS USING AN UAS

Abstract. 3D terrain models are an important instrument in areas like geology, agriculture and reconnaissance. Using an automated UAS with a line-based LiDAR can create terrain models fast and easily even from large areas. But the resulting point cloud may contain holes and therefore be incomplete. This might happen due to occlusions, a missed flight route due to wind or simply as a result of changes in the ground height which would alter the swath of the LiDAR system. This paper proposes a method to detect holes in 3D point clouds generated during the flight and adjust the course in order to close them. First, a grid-based search for holes in the horizontal ground plane is performed. Then a check for vertical holes mainly created by buildings walls is done. Due to occlusions and steep LiDAR angles, closing the vertical gaps may be difficult or even impossible. Therefore, the current approach deals with holes in the ground plane and only marks the vertical holes in such a way that the operator can decide on further actions regarding them. The aim is to efficiently create point clouds which can be used for the generation of complete 3D terrain models.

Peg-In-Hole search using convex optimization techniques

PurposeThis paper aims to provide a solution to the first phase of a force-controlled circular Peg-In-Hole assembly using an industrial robot. The paper suggests motion planning of the robot’s end-effector so as to perform Peg-In-Hole search with minimum a priori information of the working environment.Design/methodology/approachThe paper models Peg-In-Hole search problem as a problem of finding the minima in depth profile for a particular assembly. Thereafter, various optimization techniques are used to guide the robot to locate minima and complete the hole search. This approach is inspired by a human’s approach of searching a hole by moving peg in various directions so as to search a point of maximum insertion which is same as the minima in depth profile.FindingsThe usage of optimization techniques for hole search allows the robot to work with minimum a priori information of the working environment. Also, the iterative nature of the techniques adapts to any disturbance during assembly.Practical implicationsThe techniques discussed here are quite useful if a force-controlled assembly needs to be performed in a highly unknown environment and also when the assembly setup can get disturbed in between.Originality/valueThe concept is original and provides a non-conventional use of optimization techniques, not for optimization of some process directly but for an industrial robot’s motion planning.

Detectability of gravitational waves from binary black holes: Impact of precession and higher modes

Gravitational wave templates used in current searches for binary black holes omit the effects of precession of the orbital plane and higher order modes. While this omission seems not to impact the detection of sources having mass ratios and spins similar to those of GW150914, even for total masses $M > 200M_{\odot}$; we show that it can cause large fractional losses of sensitive volume for binaries with mass ratio $q \geq 4$ and $M>100M_{\odot}$, measured the detector frame. For the highest precessing cases, this is true even when the source is face-on to the detector. Quantitatively, we show that the aforementioned omission can lead to fractional losses of sensitive volume of $\sim15\%$, reaching $>25\%$ for the worst cases studied. Loss estimates are obtained by evaluating the effectualness of the SEOBNRv2-ROM double spin model, currently used in binary black hole searches, towards gravitational wave signals from precessing binaries computed by means of numerical relativity. We conclude that, for sources with $q \geq 4$, a reliable search for binary black holes heavier than $M>100M_\odot$ needs to consider the effects of higher order modes and precession. The latter seems specially necessary when Advanced LIGO reaches its design sensitivity.

A NEARLY NAKED SUPERMASSIVE BLACK HOLE

ABSTRACT During a systematic search for supermassive black holes (SMBHs) not in galactic nuclei, we identified the compact, symmetric radio source B3 1715+425 with an emission-line galaxy offset ≈ 8.5 kpc from the nucleus of the brightest cluster galaxy (BCG) in the redshift z = 0.1754 cluster ZwCl 8193. B3 1715+425 is too bright (brightness temperature T b ∼ 3 × 10 10 K at observing frequency ν = 7.6 GHz ) and too luminous (1.4 GHz luminosity L 1.4 GHz ∼ 10 25 W Hz − 1 ) to be powered by anything but an SMBH, but its host galaxy is much smaller ( ∼ 0.9 kpc × 0.6 kpc full width between half-maximum points) and optically fainter (R-band absolute magnitude M r ≈ − 18.2 ) than any other radio galaxy. Its high radial velocity v r ≈ 1860 km s − 1 relative to the BCG, continuous ionized wake extending back to the BCG nucleus, and surrounding debris indicate that the radio galaxy was tidally shredded passing through the BCG core, leaving a nearly naked SMBH fleeing from the BCG with space velocity v ≳ 2000 km s − 1 . The radio galaxy has mass M ≲ 6 × 10 9 M ⊙ and infrared luminosity L IR ∼ 3 × 10 11 L ⊙ close to its dust Eddington limit, so it is vulnerable to further mass loss from radiative feedback.

Physics‐based search and optimization: Inspirations from nature

AbstractThis paper presents a review of recently developed physics‐based search and optimization algorithms that have been inspired by natural phenomena. They include Big Bang–Big Crunch, black hole search, galaxy‐based search, artificial physics optimization, electromagnetism optimization, charged system search, colliding bodies optimization, and particle collision algorithm.