The physical nature of ultraluminous x-ray sources is uncertain. Stellar-mass black holes with beamed radiation and intermediate black holes with isotropic radiation are two plausible explanations. We discovered radio emission from an ultraluminous x-ray source in the dwarf irregular galaxy NGC 5408. The x-ray, radio, and optical fluxes as well as the x-ray spectral shape are consistent with beamed relativistic jet emission from an accreting stellar black hole. If confirmed, this would suggest that the ultraluminous x-ray sources may be stellar-mass rather than intermediate-mass black holes. However, interpretation of the source as a jet-producing intermediate-mass black hole cannot be ruled out at this time.
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Sci Rep
October 2024
Astronomy and Meteorology Department, Faculty of Science, Al-Azhar University, PO Box 11884, Nasr City, Cairo, Egypt.
We characterize luminosity components of Ultra/Luminous Infrared Galaxies (U/LIRGs) in multi-wavelength from the X-ray to far-infrared. A set of 63 AGN U/LIRGs was selected where these galaxies are powered by a central active galactic nucleus (AGN). Utilizing the X-CIGALE code, SEDs for these galaxies are carried out where their SEDs are fitted with observations.
View Article and Find Full Text PDFSci Rep
January 2021
Faculty of Physics, University of Białystok, Ciołkowskiego 1L, 15-245, Białystok, Poland.
We study the final stages of the evolution of a binary system consisted of a black hole and a white dwarf star. We implement the quantum hydrodynamic equations and carry out numerical simulations. As a model of a white dwarf star we consider a zero temperature droplet of attractively interacting degenerate atomic bosons and spin-polarized atomic fermions.
View Article and Find Full Text PDFRes Astron Astrophys
October 2018
NASA Goddard Space Flight Center, Laboratory for High-Energy Astrophysics, Code 663, Greenbelt, MD 20771, USA.
We analyse the most powerful X-ray outbursts from neutron stars in ten Magellanic high-mass X-ray binaries and three pulsating ultraluminous X-ray sources. Most of the outbursts rise to which is about the level of the Eddington luminosity, while the rest and more powerful outbursts also appear to recognize that limit when their emissions are assumed to be anisotropic and beamed toward our direction. We use the measurements of pulsar spin periods and their derivatives to calculate the X-ray luminosities in their faintest accreting ("propeller") states.
View Article and Find Full Text PDFNature
October 2018
Anton Pannekoek Institute for Astronomy, University of Amsterdam, Amsterdam, The Netherlands.
Relativistic jets are observed throughout the Universe and strongly affect their surrounding environments on a range of physical scales, from Galactic binary systems to galaxies and clusters of galaxies. All types of accreting black hole and neutron star have been observed to launch jets, with the exception of neutron stars with strong magnetic fields (higher than 10 gauss), leading to the conclusion that their magnetic field strength inhibits jet formation. However, radio emission recently detected from two such objects could have a jet origin, among other possible explanations, indicating that this long-standing idea might need to be reconsidered.
View Article and Find Full Text PDFAstrophys J
August 2018
Praxis Inc., Arlington, VA 22202, USA.
Swift J0243.6+6124 is a newly discovered Galactic Be/X-ray binary, revealed in late September 2017 in a giant outburst with a peak luminosity of 2 × 10(/7 kpc) erg s (0.1-10 keV), with no formerly reported activity.
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