Strong Gravitational Field Diagnostics in Binary Systems Containing a Compact Object

Author(s):  
L. Stella
Author(s):  
R Pattnaik ◽  
K Sharma ◽  
K Alabarta ◽  
D Altamirano ◽  
M Chakraborty ◽  
...  

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.


2009 ◽  
Vol 289-292 ◽  
pp. 319-322 ◽  
Author(s):  
Yusuke Iguchi ◽  
Masao Ono ◽  
Satoru Okayasu ◽  
Tsutomu Mashimo

An atomic-scale graded structure has been formed by sedimentation of substitutional atoms under an ultra-strong gravitational field of 1 million G level in alloys and compounds. In this study, we investigate the sedimentation of impurity atoms in semiconductor materials under a strong gravitational field. High-temperature ultracentrifuge experiments (0.59×106 G, 400°C, 60 hours) have been performed on an InSb single crystal wafer which surface was coated with Ge by means of Physical Vapor Deposition (PVD). It was observed that the penetration depth of diffused Ge atoms under the gravitational field was several times larger than under terrestrial field at the same temperatures.


Author(s):  
Y. Iguchi ◽  
H. Shibata ◽  
Y. Uchida ◽  
Xin Sheng Huang ◽  
Masao Ono ◽  
...  

1974 ◽  
Vol 64 ◽  
pp. 194-212
Author(s):  
M. J. Rees

The physics of spherically symmetrical accretion onto a compact object is briefly reviewed. Neither neutron stars nor stellar-mass black holes are likely to be readily detectable if they are isolated and accreting from the interstellar medium. Supermassive black holes in intergalactic space may however be detectable. The effects of accretion onto compact objects in binary systems are then discussed, with reference to the phenomena observed in variable X-ray sources.


2017 ◽  
Vol 120 ◽  
pp. 379-383 ◽  
Author(s):  
Nasrin Jewena ◽  
Ryota Miyanomae ◽  
Mitsuru Sasaki ◽  
Tsutomu Mashimo

2009 ◽  
Vol 289-292 ◽  
pp. 357-360 ◽  
Author(s):  
Tsutomu Mashimo ◽  
Yusuke Iguchi ◽  
Rabaya Bagum ◽  
Tomokazu Sano ◽  
S. Takeda ◽  
...  

A visible four-layers structure with anomalous nano-sturucture was formed from a homogeneous -phase Bi3Pb7 intermetallic compound under a strong gravitational field (1.02x106 G, 130°C, 100 hours). In the 4th layer (lowest-gravity region), pure Bi particles precipitate. In the 2nd 3rd layers, composition graded structures, where Pb content increased along the gravity direction, were formed. It was found that the very broad XRD peak appeared in the 2nd layer, which indicated that an amorphous structure was contained.


2005 ◽  
Vol 237-240 ◽  
pp. 1101-1106 ◽  
Author(s):  
Masao Ono ◽  
Xin Sheng Huang ◽  
Takahiro Kinoshita ◽  
Hideto Ueno ◽  
Toyotaka Osakabe ◽  
...  

Ultra-strong gravitational field can induce sedimentation of even atoms in condensed matter. We had realized sedimentation of substitutional solute atoms in some miscible alloys. In this study, the ultra-centrifuge experiments were performed on an intermetallic compound of Bi-Pb system (Bi3Pb7) by changing time duration of experiment time (experimental conditions; maximum centrifugal force: 1.0x106g level, temperature: 130-150 °C, duration: 30-150h, state: solid). Composition changes were observed in the centrifuged samples. And, it was found that the Bi phase appeared from starting state of Bi3Pb7 around the weak gravitational field region of the sample. These results showed that sedimentation of substitutional solute atoms occurred, and induced the structure change in intermetallic compounds.


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