Object Mergers Research Articles

Electromagnetic counterpart to gravitational waves from coalescence of binary black hole with magnetic monopole charge

A Satellite Fermi GBM detected recent putative short Gamma Ray Bursts (GRBs) in coincident with the gravitational wave signal GW 150914 produced by the merger of binary black hole (BH). If at least one BH possess magnetic monopole charge in the binary BH system then the short-duration GRBs may produce during the final phase of a binary BH merger. The detection of gravitational waves GW 150914, GW 151226 and LVT 151012 by LIGO gave the evidence that merging of the compact object like binary BH often happens in our universe. In this paper, we report the qualitative model to discuss the generation of electromagnetic radiation from the merging of two BHs with equal masses and at least one BH carrying the magnetic monopole charge in the binary system. In this model, BH possess a magnetic monopole charge that may not be neutralized before the coalescence. During the inspiralling process, the magnetic monopole charge on the BH would produced the electric dipole moment. Short duration GRB would produce by the rapidly evolution of the electric dipole moment which may detectable on Earth. We predict that this model would be beneficial in the future to explain the generation of gravitational wave (GW) plus a electromagnetic signal of multi-wavelength from mergers of magnetically charged BHs.

Discriminating between Neutron Stars and Black Holes with Imperfect Knowledge of the Maximum Neutron Star Mass

Abstract Although gravitational-wave signals from exceptional low-mass compact binary coalescences, like GW170817, may carry matter signatures that differentiate the source from a binary black hole system, only one out of every eight events detected by the current Advanced LIGO and Virgo observatories are likely to have signal-to-noise ratios large enough to measure matter effects, even if they are present. Nonetheless, the systems’ component masses will generally be constrained precisely. Constructing an explicit mixture model for the total rate density of merging compact objects, we develop a hierarchical Bayesian analysis to classify gravitational-wave sources according to the posterior odds that their component masses are drawn from different subpopulations. Accounting for current uncertainty in the maximum neutron star mass and adopting a power-law mass distribution with or without a mass gap and either random or mass-ratio-dependent pairing, we examine two recent events from the LIGO–Virgo Collaboration’s third observing run, GW190425 and GW190814. For population models with no overlap between the neutron star and black hole mass distributions, we typically find that there is a chance, depending on the exact population model, that GW190425 was a binary neutron star merger rather than a neutron-star–black-hole merger. On the other hand, we find that there is a chance that GW190814 involved a slowly spinning neutron star, regardless of our assumed population model.

Morphometric analysis of brightest cluster galaxies

ABSTRACT We study the build-up of the stellar mass of brightest cluster galaxies (BCGs) at z < 0.1 as a function of their morphological type. Morphometric parameters for 1216 BCGs were obtained from the SDSS DR12 r-band images with the code morfometryka. We show that the morphometric parameters are efficient to separate BCGs into cD galaxies, conventional ellipticals, disc-dominated BCGs, and merging objects. We propose a simple classification scheme using two concentration indices, C1 and C2, and the spirality σψ. We then investigate how the stellar masses of BCGs and the velocity dispersions of their parent haloes relate to their morphological properties. We find that BCGs with larger envelope contributions are more massive than BCGs in other classes and more common in massive clusters. The stellar mass and the halo velocity dispersion correlate for all classes, suggesting that environmental effects are important for BCGs of any morphology. At fixed parent halo mass, we detect a continuous mass excess up to $\sim 60{{\ \rm per\ cent}}$ from pure E galaxies to extreme cD galaxies, while the inner regions of such cDs present only $\sim 40{{\ \rm per\ cent}}$ of the mass of an E galaxy. We interpret our findings in a scenario where different BCGs have developed their mass through an asymmetric combination of distinct processes, so that present-time cD galaxies have grown in mass mainly through minor merging and tidal stripping from satellite galaxies, while elliptical BCGs evolve mainly through processes like major merging.

Maximum force and naked singularities in higher dimensions

We discuss the existence of maximum forces in ([Formula: see text])-dimensional spacetimes and show that the existence of a mass-independent maximum force does not occur in general relativity in spaces of more than three dimensions. Instead, the maximum force increases with the masses of merging objects as [Formula: see text] and allows unbounded gravitational forces to occur. This suggests that naked singularities can arise in more than three dimensions because they are unprotected by a maximum force at the horizon surface. This creates a new perspective on the expectation of naked singularities in higher dimensions.

On the distinction between uptake and perlocutionary object: the case of issuing and obeying orders

ABSTRACTThis essay investigates and criticizes Austin’s distinction between uptake and perlocutionary object, focusing on the speech act of ordering someone to do something. Pace Austin’s analysis, it is argued that in central and typical cases of ordering, uptake and perlocutionary object merge. In such cases, understanding and obeying an order amount to the same thing. By contrast, in cases where the order is subject to critical scrutiny or disobeyed, uptake and perlocutionary object are distinct. The reasons for and nature of such a disjunctivist conception of uptake are spelt out by reference to Wittgenstein’s discussion of rule-following in the Philosophical Investigations. It is suggested that such a disjunctivist conception calls for substantive revisions of Austin’s conception of illocution.

Dependence of gravitational wave transient rates on cosmic star formation and metallicity evolution history

ABSTRACT We compare the impacts of uncertainties in both binary population synthesis models and the cosmic star formation history on the predicted rates of gravitational wave (GW) compact binary merger events. These uncertainties cause the predicted rates of GW events to vary by up to an order of magnitude. Varying the volume-averaged star formation rate density history of the Universe causes the weakest change to our predictions, while varying the metallicity evolution has the strongest effect. Double neutron star merger rates are more sensitive to assumed neutron star kick velocity than the cosmic star formation history. Varying certain parameters affects merger rates in different ways depending on the mass of the merging compact objects; thus some of the degeneracy may be broken by looking at all the event rates rather than restricting ourselves to one class of mergers.

Filling the Mass Gap: How Kilonova Observations Can Unveil the Nature of the Compact Object Merging with the Neutron Star

Abstract In this Letter we focus on the peculiar case of a coalescing compact-object binary whose chirp mass is compatible both with a neutron star–neutron star and black hole–neutron star system, with the black hole in the ∼3–5 M ⊙ range defined as the “mass gap.” Some models of core-collapse supernovae predict the formation of such low-mass black holes and a recent observation seems to confirm their existence. Here we show that the nature of the companion to the neutron star can be inferred from the properties of the kilonova emission once we know the chirp mass, which is the best constrained parameter inferred from the gravitational signal in low-latency searches. In particular, we find that the kilonova in the black hole–neutron star case is far more luminous than in the neutron star–neutron star case, even when the black hole is nonspinning. The difference in the kilonovae brightness arises primarily from the mass ejected during the merger. Indeed, in the considered interval of chirp masses, the mass ejection in double neutron star mergers is at its worst as the system promptly forms a black hole. Instead mass ejection for the black hole–neutron star case is at its best as the neutron stars have low mass/large deformability. The kilonovae from black hole–neutron star systems can differ by two to three magnitudes. The outcome is only marginally dependent on the equation of state. The difference is above the systematics in the modeling.

The connection between merging double compact objects and the Ultraluminous X-ray Sources

Abstract We explore the different formation channels of merging double compact objects (DCOs: BH-BH/BH-NS/NS-NS) that went through a ultraluminous X-ray phase (ULX: X-ray sources with apparent luminosity exceeding $10^{39}\rm {\ erg\ s^{-1}}$). There are many evolutionary scenarios which can naturally explain the formation of merging DCO systems: isolated binary evolution, dynamical evolution inside dense clusters and chemically homogeneous evolution of field binaries. It is not clear which scenario is responsible for the majority of LIGO/Virgo sources. Finding connections between ULXs and DCOs can potentially point to the origin of merging DCOs as more and more ULXs are discovered. We use the StarTrack population synthesis code to show how many ULXs will form merging DCOs in the framework of isolated binary evolution. Our merger rate calculation shows that in the local Universe typically $50\%$ of merging BH-BH progenitor binaries have evolved through a ULX phase. This indicates that ULXs can be used to study the origin of LIGO/Virgo sources. We have also estimated that the fraction of observed ULXs that will form merging DCOs in future varies between $5\%$ to $40\%$ depending on common envelope model and metallicity.

Topology Based Object Tracking

A model for tracking objects whose topological properties change over time is proposed. Such changes include the splitting of an object into multiple objects or the merging of multiple objects into a single object. The proposed model employs a novel formulation of the tracking problem in terms of homology theory whereby 0-dimensional homology classes, which correspond to connected components, are tracked. A generalisation of this model for tracking spatially close objects lying in an ambient metric space is also proposed. This generalisation is particularly suitable for tracking spatial-temporal phenomena such as rain clouds. The utility of the proposed model is demonstrated with respect to tracking communities in a social network and tracking rain clouds in radar imagery.

Dark Matter Objects: Possible New Source of Gravitational Waves

Gravitational waves from mergers of black holes and neutron stars are now being detected by LIGO. Here we look at a new source of gravitational waves, i.e., a class of dark matter objects whose properties were earlier elaborated. We show that the frequency of gravitational waves and strains on the detectors from such objects (including their mergers) could be within the sensitivity range of LIGO. The gravitational waves from the possible mergers of these dark matter objects will be different from those produced by neutron star mergers in the sense that they will not be accompanied by electromagnetic radiation since dark matter does not couple with radiation.

A Process-Oriented Method for Tracking Rainstorms with a Time-Series of Raster Datasets

Extreme rainstorms have important socioeconomic consequences, but understanding their fine spatial structures and temporal evolution still remains challenging. In order to achieve this, in view of an evolutionary property of rainstorms, this paper designs a process-oriented algorithm for identifying and tracking rainstorms, named PoAIR. PoAIR uses time-series of raster datasets and consists of three steps. The first step combines an accumulated rainfall time-series and spatial connectivity to identify rainstorm objects at each time snapshot. Secondly, PoAIR adopts the geometrical features of eccentricity, rectangularity, roundness, and shape index, as well as the thematic feature of the mean rainstorm intensity, to match the same rainstorm objects in successive snapshots, and then tracks the same rainstorm objects during a rainstorm evolution sequence. In the third step, an evolutionary property of a rainstorm sequence is used to extrapolate its spatial location and geometrical features at the next time snapshot and reconstructs a rainstorm process by linking rainstorm sequences with an area-overlapping threshold. Experiments on simulated datasets demonstrate that PoAIR performs better than the Thunderstorm Identification, Tracking, Analysis and Nowcasting algorithm (TITAN) in both rainfall tracking and identifying the splitting, merging, and merging-splitting of rainstorm objects. Additionally, applications of PoAIR to Integrated Multi-satellitE Retrievals for Global Precipitation Mission (GPM/IMERG) final products covering mainland China show that PoAIR can effectively track rainstorm objects.

Orbits through polytropes

We describe how orbital tunnels could be used to transport payloads through the Earth. If you use a brachistochrone for the tunnel, the body forces in the tunnel become overwhelmingly large for small angular distances traveled. Projectiles move along an orbital tunnel faster than they would along a brachistochrone connecting the same points but the body force components cancel. We describe how parabolic Keplerian orbits outside the object merge onto quasi-Keplerian orbits inside the object. We use models of the interior of the Earth with three values of the polytropic index (n) to calculate interior orbits that travel between surface points. The n = 3 results are also scaled to the Sun. Numerical integrations of the equations describing polytropes were used to generate the initial models. Numerical integration of the equations of motion are then used to calculate the angular distance you can travel along the surface and the traversal time as a function of the parabolic periapsis distance for each model. Trajectories through objects of low central condensation show a focussing effect that decreases as the central condensation increases. Analytic solutions for the trajectories in a homogeneous sphere are derived and compared to the numeric results. The results can be scaled to other planets, stars, or even globular clusters.

Host galaxies of merging compact objects: mass, star formation rate, metallicity, and colours

Characterizing the properties of the host galaxies of merging compact objects provides essential clues to interpret current and future gravitational-wave detections. Here, we investigate the stellar mass, star formation rate (SFR), metallicity and colours of the host galaxies of merging compact objects in the local Universe, by combining the results of MOBSE population-synthesis models together with galaxy catalogs from the EAGLE simulation. We predict that the stellar mass of the host galaxy is an excellent tracer of the merger rate per galaxy ${\rm n}_{\rm GW}$ of double neutron stars (DNSs), double black holes (DBHs) and black hole-neutron star binaries (BHNSs). We find a significant correlation also between ${\rm n}_{\rm GW}$ and SFR. As a consequence, ${\rm n}_{\rm GW}$ correlates also with the $r-$band luminosity and with the $g-r$ colour of the host galaxies. Interestingly, $\gtrsim{}60$ %, $\gtrsim{}64$ % and $\gtrsim{}73$ % of all the DNSs, BHNSs and DBHs merging in the local Universe lie in early-type galaxies, such as NGC 4993. We predict a local DNS merger rate density of $\sim{}238~{\rm Gpc}^{-3}~{\rm yr}~^{-1}$ and a DNS merger rate $\sim{}16-121$ Myr$^{-1}$ for Milky Way-like galaxies. Thus, our results are consistent with both the DNS merger rate inferred from GW170817 and the one inferred from Galactic DNSs.

The properties of merging black holes and neutron stars across cosmic time

The next generation ground-based gravitational wave interferometers will possibly observe mergers of binary black holes (BBHs) and binary neutron stars (BNSs) to redshift $z\gtrsim{}10$ and $z\gtrsim{}2$, respectively. Here, we characterize the properties of merging BBHs, BNSs and neutron star-black hole binaries across cosmic time, by means of population-synthesis simulations combined with the Illustris cosmological simulation. We find that the mass of merging compact objects does not depend (or depends very mildly) on the merger redshift. Even the mass distribution of black holes depends only mildly on redshift, because BBHs originating from metal-poor progenitors ($Z\leq{}4\times{}10^{-3}$) dominate the entire population of merging BBHs across cosmic time. For a common-envelope efficiency $\alpha{}\ge{}3$, the main difference between the mass distribution of BBHs merging in the last Gyr and that of BBHs merging more than 11 Gyr ago is that there is an excess of heavy merging black holes ($20-35$ M$_\odot$) in the last Gyr. This excess is explained by the longer delay time of massive BBHs.

Gravitational waveforms from spectral Einstein code simulations: Neutron star-neutron star and low-mass black hole-neutron star binaries

Gravitational waveforms from numerical simulations are a critical tool to test and analytically calibrate the waveform models used to study the properties of merging compact objects. In this paper, we present a series of high-accuracy waveforms produced with the SpEC code for systems involving at least one neutron star. We provide for the first time waveforms with sub-radian accuracy over more than twenty cycles for low-mass black hole-neutron star binaries, including binaries with non-spinning objects, and binaries with rapidly spinning neutron stars that maximize the impact on the gravitational wave signal of the near-resonant growth of the fundamental excitation mode of the neutron star (f-mode). We also provide for the first time with SpEC a high-accuracy neutron star-neutron star waveform. These waveforms are made publicly available as part of the SxS catalogue. We compare our results to analytical waveform models currently implemented in data analysis pipelines. For most simulations, the models lie outside of the predicted numerical errors in the last few orbits before merger, but do not show systematic deviations from the numerical results: comparing different models appears to provide reasonable estimates of the modeling errors. The sole exception is the equal-mass simulation using a rapidly counter-rotating neutron star to maximize the impact of the excitation of the f-mode, for which all models perform poorly. This is however expected, as even the single model that takes f-mode excitation into account ignores the significant impact of the neutron star spin on the f-mode excitation frequency.

Development of Spatio-Temporal Database Prototype For Management of 4-Dimensional Cadastre Object In Indonesia

The dynamics of the Indonesian population has increased causing the need for cadastral objects to increase. 2D and 3D cadastral objects change over time. Cadastral objects have spatial and juridical data changes every day. These changes can be caused by the transfer of rights, changes of rights, split and merging cadastral objects. Changes are recorded and stored as a history of cadastral objects (4-dimensional cadastre). Historical data on cadastral objects can be categorized as one of the big data in the cadastre sector, based on the frequency of recording data. The data can be used to track changes in cadastral objects so that they can avoid disputes. Spatial data in this case is very vulnerable data to cause disputes if the shape, position and size do not match the conditions in the field, and need special attention in integrating with the juridical data. This paper aims to identify methods for storing spatial data of 4D cadastral objects that are suitable for Indonesia. The importance of storing cadastral objects and their history causes researchers and cadastre experts in the world to formulate international standards in managing spatial and juridical data along with a history of cadastral objects (4D cadastre). LADM is an international standard conceptual model (ISO 19152) which can show the legacy of a cadastral object expressed in RRR (Rights, Restriction and Responsibility). In LADM, there is a VersionedObject class that represents various versions or a history of spatial units, object registration, owner and administration. Several studies conducted by researchers in the world were compared in this paper to find methods for applying LADM and VersionedObject classes. That methods were implemented in this paper to design a database of spatio-temporal 4D cadastre. Finally a prototype of spatial-temporal database will be produced to manage 4D cadastral objects.

Detailed polarization measurements of the prompt emission of five gamma-ray bursts

Gamma-ray bursts are the strongest explosions in the Universe since the Big Bang, believed to be produced either in forming black holes at the end of massive star evolution or merging of compact objects. Spectral and timing properties of gamma-ray bursts suggest that the observed bright gamma-rays are produced in the most relativistic jets in the Universe; however, the physical properties, especially the structure and magnetic topologies in the jets are still not well known, despite several decades of studies. It is widely believed that precise measurements of the polarization properties of gamma-ray bursts should provide crucial information on the highly relativistic jets. As a result there have been many reports of gamma-ray burst polarization measurements with diverse results, see, however many such measurements suffered from substantial uncertainties, mostly systematic. After the first successful measurements by the GAP and COSI instruments, here we report a statistically meaningful sample of precise polarization measurements, obtained with the dedicated gamma-ray burst polarimeter, POLAR onboard China's Tiangong-2 spacelab. Our results suggest that the gamma-ray emission is at most polarized at a level lower than some popular models have predicted; although our results also show intrapulse evolution of the polarization angle. This indicates that the low polarization degrees could be due to an evolving polarization angle during a gamma-ray burst.

Binary neutron stars and production of heavy elements

We show how merging neutron stars can be responsible for the production of heavy elements in the solar vicinity, in particular we study the evolution of the abundance of europium (Eu) relative to iron (Fe), as derived by stellar abundances measured in the Milky Way halo and disk stars. To do that, we adopt a detailed galactic chemical evolution model able to follow the evolution of the abundances of several chemical elements in the gas in our Galaxy. Merging of neutron stars after emission of gravitational waves has been observed for the first time in the event GW170817, which has represented the very first kilonova ever observed in the local universe. The production of heavy elements such as Eu (a typical r-process element) is discussed critically, pointing out that supernovae core collapse can produce some r-process elements but not enough to explain the solar abundance of Eu. On the other hand, the merging of compact objects can provide an amount of Eu much higher per single event than a single supernova. We discuss the various parameters involved, such as the merging timescales, the fraction of neutron star binaries and the present time rate of kilonova explosions. We compare model results with stellar data and conclude that merging of compact objects can be responsible for the bulk of Eu production in the Galaxy under some assumptions: (i) the merging binaries should have progenitors in the mass range 9–50$$M_{\odot }$$, (ii) the merging timescales should be as short as 1 Myr and iii) each event should produce $$\sim 2 \times 10^{-6}M_{\odot }$$. We also conclude that the Ligo/Virgo merging neutron star rate is consistent with our chemical evolution model and that if GW170817 is a representative event, then the merging neutron stars can be considered as the main r-process production sites.

Study of Lithium Rich Giants with the GALAH Spectroscopic Survey

In this article, we speculate on the possible mechanisms for Li enhancement origin in RGB stars based on a large data set of around 340,299 stars collected from the GALAH survey combined with the Gaia astrometry. Data has 51,982 low mass (M$\leq$ 2M$_{\odot}$) RGB stars with reliable atmospheric parameters. The data set shows a well populated RGB with well-defined luminosity bump and red clump with significant number of stars at each of these two key phases. We found 335 new Li-rich RGB stars with Li abundance, A(Li) $\geq$ 1.80 $\pm$ 0.14 dex, of which 20 are super Li-rich with A(Li) $\geq$ 3.20~dex. Most of them appear to be in the red clump region which, when combined with stellar evolutionary timescales on RGB, indicates that the Li enhancement origin may lie at RGB tip during He-flash rather than by external source of merging of sub-stellar objects or during luminosity bump evolution. Kinematic properties of sample stars suggest that Li-rich giants are relatively more prevalent among giants of thin disk compared to thick disk and halo.

Wonder Cards Storytelling: Imagination, Storytelling, and Role-playing in the Creation of Objects, Spaces, and Experiences

This article explores storytelling and role-playing as resources to create objects, spaces, and experiences in the field of design. To this end, we present Wonder Cards. The game is an “imagination instrument” that, through distant analogies (de Cruz and de Smedt 2010), assist in the development of narratives. A tale needs to arouse feelings – empathy, love, fear, nostalgia, and many others. The materiality of this abstraction helps the individual generate notions of belonging and temporality for himself and for others (Pallasma 2012). Human beings express themselves through objects and spaces: what we call our material culture. They are an indispensable part of the materialization of sensations and affect. Accordingly, magnificent tales create memories that express the objects and spaces invented. Objects and spaces within an intrinsic narrative create memory. Memory helps construct and preserve cultural and personal identity, since living itself is a constant movement toward recollection (Cardoso 2011). Therefore, the merging of objects with subjectivity is exceedingly important to culture construction. Nonetheless, how does one create these tales? Structures can facilitate this creative process. This article presents the constitutive elements of our creative tool, the implemented experiments, discussions, and debriefings (Atwater 2016) derived from the use of the card game on workshops and design classes at Pontifical Catholic University of Rio de Janeiro. These activities with participants, objects, spaces, and experiences are explored by the creation of narrative scenes and storytelling resources through fantasy (Barthes 2013) and role-playing (Bienia 2016) and by using the Wonder Cards. This union enables the participants to live situations removed from the creative environment where they usually work, thus stimulating creation in new situations and imaginary narrative environments. The Wonder Cards assist in the construction of tales, which inspire the development of objects, spaces, and experiences by the participants.