scholarly journals Black Hole Gravitational Potential Enhanced Fallback Accretion onto the Nascent Lighter Compact Object: Tentative Evidence in the O3 Run Data of LIGO/Virgo

2021 ◽  
Vol 922 (1) ◽  
pp. 3
Author(s):  
Shao-Peng Tang ◽  
Yin-Jie Li ◽  
Yuan-Zhu Wang ◽  
Yi-Zhong Fan ◽  
Da-Ming Wei
Keyword(s):  
Black Hole ◽  
Mass Distribution ◽  
Gravitational Potential ◽  
Compact Object ◽  
Supernova Explosion ◽  
Small Mass ◽  
Compact Objects ◽  
Mass Ratio ◽  
Tentative Evidence ◽  
Low Mass

Abstract In a binary system, the gravitational potential of the primary black hole may play an important role in enhancing the fallback accretion onto the lighter compact object newly formed in the second supernova explosion. As a result, the final masses of the binary compact objects would be correlated, as suggested recently by Safarzadeh & Wysocki. In this work, we analyze the mass distribution of four gravitational-wave events, which are characterized by both a small mass ratio and a low mass (≤5M ⊙) of the light component, and find tentative evidence for a mass correlation among the objects. To evaluate the feasibility of testing such a hypothesis with upcoming observations, we carry out simulations with a mock population and perform Bayesian hierarchical inference for the mass distribution. We find that with dozens of low mass ratio events, whether there exists correlation in the component mass distributions or not can be robustly tested and the correlation, if it exists, can be well determined.

scholarly journals Measuring the Masses of Compact Objects in Low-Mass X-Ray Binaries

2004 ◽  
Vol 194 ◽  
pp. 214-214
Author(s):  
Dawn M. Gelino
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Compact Object ◽  
Compact Objects ◽  
Orbital Inclination ◽  
X Ray ◽  
Secondary Star ◽  
Low Mass ◽  
The Masses ◽  
X Ray Binaries

Low-mass X-ray binaries (LMXBs) contain compact, black hole (BH) or neutron star (NS) primaries, and cool, low-mass secondary stars. We measure the orbital inclination of the system in quiescence by modeling infrared (IR) ellipsoidal variations from the secondary star in order to determine the compact object mass. I present our results for a few LMXBs, including the first BH that appears to conclusively fall in the 3-5 M⊙ range.

scholarly journals A Machine Learning Approach For Classifying Low-mass X-ray Binaries Based On Their Compact Object Nature

2020 ◽  
Author(s):  
R Pattnaik ◽  
K Sharma ◽  
K Alabarta ◽  
D Altamirano ◽  
M Chakraborty ◽  
...  
Keyword(s):  
Machine Learning ◽  
Black Hole ◽  
Neutron Star ◽  
Binary Systems ◽  
Compact Object ◽  
X Ray ◽  
Average Accuracy ◽  
Machine Learning Approach ◽  
Low Mass ◽  
X Ray Binaries

Abstract Low Mass X-ray binaries (LMXBs) are binary systems where one of the components is either a black hole or a neutron star and the other is a less massive star. It is challenging to unambiguously determine whether a LMXB hosts a black hole or a neutron star. In the last few decades, multiple observational works have tried, with different levels of success, to address this problem. In this paper, we explore the use of machine learning to tackle this observational challenge. We train a random forest classifier to identify the type of compact object using the energy spectrum in the energy range 5-25 keV obtained from the Rossi X-ray Timing Explorer archive. We report an average accuracy of 87±13% in classifying the spectra of LMXB sources. We further use the trained model for predicting the classes for LMXB systems with unknown or ambiguous classification. With the ever-increasing volume of astronomical data in the X-ray domain from present and upcoming missions (e.g., SWIFT, XMM-Newton, XARM, ATHENA, NICER), such methods can be extremely useful for faster and robust classification of X-ray sources and can also be deployed as part of the data reduction pipeline.

scholarly journals Cosmological black holes are not described by the Thakurta metric: LIGO-Virgo bounds on PBHs remain unchanged

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Gert Hütsi ◽  
Tomi Koivisto ◽  
Martti Raidal ◽  
Ville Vaskonen ◽  
Hardi Veermäe
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Compact Object ◽  
Compact Objects ◽  
Primordial Black Hole ◽  
Mass Growth ◽  
Black Hole Binaries ◽  
Physical Conditions ◽  
Accretion Physics

AbstractWe show that the physical conditions which induce the Thakurta metric, recently studied by Bœhm et al. in the context of time-dependent black hole masses, correspond to a single accreting compact object in the entire Universe filled with isotropic non-interacting dust. In such a case, accretion physics is not local but tied to the properties of the whole Universe. We show that radiation, primordial black holes or particle dark matter cannot produce the specific energy flux required for supporting the mass growth of the compact objects described by the Thakurta metric. In particular, this solution does not apply to black hole binaries. We conclude that compact dark matter candidates and their mass growth cannot be described by the Thakurta metric, and thus existing constraints on the primordial black hole abundance from the LIGO-Virgo and the CMB measurements remain valid.

On the nonlinear performance of a tuned sloshing damper under small amplitude excitation

2019 ◽  
Vol 25 (21-22) ◽  
pp. 2695-2705 ◽  
Author(s):  
Anuja Roy ◽  
Zili Zhang ◽  
Aparna (Dey) Ghosh ◽  
Biswajit Basu
Keyword(s):  
Small Amplitude ◽  
Numerical Study ◽  
Nonlinear Behavior ◽  
Wave Theory ◽  
Small Mass ◽  
Mass Ratio ◽  
Hybrid Testing ◽  
Low Mass ◽  
Low Mass Ratio ◽  
Nonlinear Performance

This paper explores the potential of a tuned sloshing damper (TSD) in the control of small amplitude vibrations, which is often important from serviceability considerations, through the use of a relatively small mass ratio of the damper liquid. To investigate the nonlinear behavior of the TSD, real-time hybrid testing is conducted in which a single rectangular tank containing water constitutes the prototype TSD. The structure is modeled as a multi-degree-of-freedom system. Two different base input motions, namely harmonic and synthetically generated broad-banded input, are considered. The sensitivity of the TSD performance to tuning ratio vis-à-vis low mass ratio is studied. The experimental results are compared with those obtained from a numerical study carried out using the shallow water wave theory-based nonlinear, semi-empirical model, for the simulation of the sloshing motion of the TSD liquid (water). Results indicate that in the tuned condition, even with a low mass ratio, the TSD is highly effective in the suppression of the small amplitude vibrations, which is underestimated by the simulation model.

scholarly journals Further evidence for the non-existence of a unified hoop conjecture

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
Shahar Hod
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Critical Mass ◽  
Compact Object ◽  
Compact Objects ◽  
Necessary Condition ◽  
Adm Mass ◽  
Black Hole Spacetimes ◽  
Opposite Inequality ◽  
Hoop Conjecture

AbstractThe hoop conjecture, introduced by Thorne almost five decades ago, asserts that black holes are characterized by the mass-to-circumference relation $$4\pi {\mathcal {M}}/{\mathcal {C}}\ge 1$$ 4 π M / C ≥ 1 , whereas horizonless compact objects are characterized by the opposite inequality $$4\pi {\mathcal {M}}/{\mathcal {C}}<1$$ 4 π M / C < 1 (here $${\mathcal {C}}$$ C is the circumference of the smallest ring that can engulf the self-gravitating compact object in all azimuthal directions). It has recently been proved that a necessary condition for the validity of this conjecture in horizonless spacetimes of spatially regular charged compact objects is that the mass $${\mathcal {M}}$$ M be interpreted as the mass contained within the engulfing sphere (and not as the asymptotically measured total ADM mass). In the present paper we raise the following physically intriguing question: is it possible to formulate a unified version of the hoop conjecture which is valid for both black holes and horizonless compact objects? In order to address this important question, we analyze the behavior of the mass-to-circumference ratio of Kerr–Newman black holes. We explicitly prove that if the mass $${\mathcal {M}}$$ M in the hoop relation is interpreted as the quasilocal Einstein–Landau–Lifshitz–Papapetrou and Weinberg mass contained within the black-hole horizon, then these charged and spinning black holes are characterized by the sub-critical mass-to-circumference ratio $$4\pi {\mathcal {M}}/{\mathcal {C}}<1$$ 4 π M / C < 1 . Our results provide evidence for the non-existence of a unified version of the hoop conjecture which is valid for both black-hole spacetimes and spatially regular horizonless compact objects.

scholarly journals Constraint on Hybrid Stars with Gravitational Wave Events

Universe ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. 231
Author(s):  
Kilar Zhang ◽  
Feng-Li Lin
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Compact Object ◽  
Compact Objects ◽  
Compact Stars ◽  
Hybrid Star ◽  
Hybrid Stars

Motivated by the recent discoveries of compact objects from LIGO/Virgo observations, we study the possibility of identifying some of these objects as compact stars made of dark matter called dark stars, or the mix of dark and nuclear matters called hybrid stars. In particular, in GW190814, a new compact object with 2.6 M⊙ is reported. This could be the lightest black hole, the heaviest neutron star, and a dark or hybrid star. In this work, we extend the discussion on the interpretations of the recent LIGO/Virgo events as hybrid stars made of various self-interacting dark matter (SIDM) in the isotropic limit. We pay particular attention to the saddle instability of the hybrid stars which will constrain the possible SIDM models.

scholarly journals Chemical abundances of secondary stars in low mass X-ray binaries

2006 ◽  
Vol 2 (S238) ◽  
pp. 43-48
Author(s):  
Jonay I. González Hernández ◽  
Rafael Rebolo ◽  
Garik Israelian
Keyword(s):  
Galactic Plane ◽  
Supernova Explosion ◽  
Compact Objects ◽  
Chemical Abundances ◽  
Mixing Processes ◽  
X Ray ◽  
Element Abundances ◽  
Supernova Explosions ◽  
Low Mass ◽  
X Ray Binaries

AbstractLow mass X-ray binaries (LMXBs) offer us an unique opportunity to study the formation processes of compact objects. Secondary stars orbiting around either a black hole or a neutron star could have captured a significant amount of the ejected matter in the supernova explosions that most likely originated the compact objects. The detailed chemical analysis of these companions can provide valuable information on the parameters involved in the supernova explosion such us the mass cut, the amount of fall-back matter, possible mixing processes, and the energy and the symmetry of the explosion. In addition, this analysis can help us to find out the birth place of the binary system. We have measured element abundances of secondary stars in the LMXBs A0620–00, Cen X-4, XTE J1118+480 and Nova Sco 94. We find solar or above solar metalicity for all these systems, what appears to be independent on their locations with respect to the Galactic plane. A comparison of the observed abundances with yields from different supernova explosion together with the kinematic properties of these systems suggest a supernova origin for the compact objects in all of them except for A0620–00, for which a direct collapse cannot be discarded.

scholarly journals Testing Gravity Theory With Extreme Mass-Ratio Inspirals: Recent Progress

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 11
Author(s):  
Shucheng Yang ◽  
Shuo Xin ◽  
Chen Zhang ◽  
Wenbiao Han
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Recent Progress ◽  
Central Body ◽  
Low Frequency ◽  
Kerr Black Hole ◽  
Compact Object ◽  
Wave Dispersion ◽  
Gravity Theory ◽  
Mass Ratio

A compact object captured by a supermassive black hole, named as extreme-mass-ratio inspiral (EMRI), is one of the most important gravitational wave sources for low-frequency interferometers such as LISA, Taiji, and TianQin. EMRIs can be used to accurately map the space-time of the central massive body. In the present paper, we introduce our recent progress on testing gravity theory with EMRIs. We demonstrate how to constrain gravitational wave dispersion and measure the deviation of the central body from the Kerr black hole. By using binary-EMRIs, the gravitational recoil and mass loss due to merger will be measured in a higher accuracy compared with the current LIGO observations. All these potential constrains and measurements will be useful for test of the gravity theory.

scholarly journals Analysis of Neutrino Burst from the Supernova in the Large Magellanic Cloud

1988 ◽  
Vol 108 ◽  
pp. 424-425
Author(s):  
Hideyuki Suzuki ◽  
Katsuhiko Sato
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Binding Energy ◽  
Massive Star ◽  
Compact Object ◽  
Supernova Explosion ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud

A massive star has been believed to end his life with the collapsed driven supernova explosion and the formation of the compact object such as a neutron star or a black hole. When the compact object is formed, a large amount of energy corresponding to the binding energy of the object must be released. It has been considered that most of the energy is emitted by neutrinos because of their adequate coupling with the matter. The observation of the neutrino burst from SN1987A by Kamiokande and IMB offered us the first chance to test these scenarios of the collapse driven supernova explosion directly. We began to analyze the data just after their publication and got many important results which are presented below. In our analysis the distance of SN1987A is assumed to be 50kpc.

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