scholarly journals Black hole, neutron star and white dwarf candidates from microlensing with OGLE-III

2016 ◽  
Vol 458 (3) ◽  
pp. 3012-3026 ◽  
Author(s):  
Ł. Wyrzykowski ◽  
Z. Kostrzewa-Rutkowska ◽  
J. Skowron ◽  
K. A. Rybicki ◽  
P. Mróz ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
White Dwarf

Galactic X- ray observations - Observations of compact X-ray sources

1979 ◽  
Vol 366 (1726) ◽  
pp. 281-293 ◽  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
White Dwarf ◽  
Compact Object ◽  
Bright Star ◽  
High Luminosity ◽  
Multiple Star ◽  
X Ray ◽  
Normal Star ◽  
Radio Outburst

The high luminosity galactic X-ray sources, apart from the supernovae remnants, probably all exist in multiple star systems in which matter from a normal star is being transferred to a compact object such as a white dwarf, neutron star or black hole. Recent results, obtained with the Ariel 5 and Copernicus satellites, are presented. A number of sources have been studied over extended periods in order to measure the regular periodicities in their X-ray emission. Observations also included are of the Cygnus X-1 source, which is probably the first black hole discovered in our galaxy. X-ray emission, coincident with a radio outburst, from a nearby bright star HR1099 is also reported.

scholarly journals FIRST RESULTS FROM THE SWARMS SURVEY. SDSS 1257+5428: A NEARBY, MASSIVE WHITE DWARF BINARY WITH A LIKELY NEUTRON STAR OR BLACK HOLE COMPANION

2009 ◽  
Vol 707 (2) ◽  
pp. 971-978 ◽  
Author(s):  
Carles Badenes ◽  
Fergal Mullally ◽  
Susan E. Thompson ◽  
Robert H. Lupton
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
White Dwarf ◽  
First Results

scholarly journals AT2018kzr: the merger of an oxygen–neon white dwarf and a neutron star or black hole

2020 ◽  
Vol 497 (1) ◽  
pp. 246-262 ◽  
Author(s):  
J H Gillanders ◽  
S A Sim ◽  
S J Smartt
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
White Dwarf ◽  
Near Infrared ◽  
Theoretical Work ◽  
Rapid Decline ◽  
Compact Binary ◽  
Fe Content ◽  
Short Time ◽  
Infrared Triplet

ABSTRACT We present detailed spectroscopic analysis of the extraordinarily fast-evolving transient AT2018kzr. The transient’s observed light curve showed a rapid decline rate, comparable to the kilonova AT2017gfo. We calculate a self-consistent sequence of radiative transfer models (using tardis) and determine that the ejecta material is dominated by intermediate-mass elements (O, Mg, and Si), with a photospheric velocity of ∼12 000–14 500 $\rm {km}\, s^{-1}$. The early spectra have the unusual combination of being blue but dominated by strong Fe ii and Fe iii absorption features. We show that this combination is only possible with a high Fe content (3.5 per cent). This implies a high Fe/(Ni+Co) ratio. Given the short time from the transient’s proposed explosion epoch, the Fe cannot be 56Fe resulting from the decay of radioactive 56Ni synthesized in the explosion. Instead, we propose that this is stable 54Fe, and that the transient is unusually rich in this isotope. We further identify an additional, high-velocity component of ejecta material at ∼20 000–26 000 $\rm {km}\, s^{-1}$, which is mildly asymmetric and detectable through the Ca ii near-infrared triplet. We discuss our findings with reference to a range of plausible progenitor systems and compare with published theoretical work. We conclude that AT2018kzr is most likely the result of a merger between an ONe white dwarf and a neutron star or black hole. As such, it would be the second plausible candidate with a good spectral sequence for the electromagnetic counterpart of a compact binary merger, after AT2017gfo.

scholarly journals The effect of the environment-dependent IMF on the formation and metallicities of stars over the cosmic history

2020 ◽  
Vol 636 ◽  
pp. A10 ◽  
Author(s):  
M. Chruślińska ◽  
T. Jeřábková ◽  
G. Nelemans ◽  
Z. Yan
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
White Dwarf ◽  
Formation Rate ◽  
Mass Function ◽  
Initial Mass Function ◽  
Stellar Initial Mass Function ◽  
Cosmic History ◽  
Exact Dependence ◽  
The Imf

Recent observational and theoretical studies indicate that the stellar initial mass function (IMF) varies systematically with the environment (star formation rate – SFR, metallicity). Although the exact dependence of the IMF on those properties is likely to change with improving observational constraints, the reported trend in the shape of the IMF appears robust. We present the first study aiming to evaluate the effect of the IMF variations on the measured cosmic SFR density (SFRD) as a function of metallicity and redshift, fSFR(Z, z). We also study the expected number and metallicity of white dwarf, neutron star, and black hole progenitors under different IMF assumptions. Applying the empirically driven IMF variations described by the integrated galactic IMF (IGIMF) theory, we revise fSFR(Z, z) obtained in our previous study that assumed a universal IMF. We find a lower SFRD at high redshifts and a higher fraction of metal-poor stars being formed than previously determined. In the local Universe, our calculation applying the IGIMF theory suggests more white dwarf and neutron star progenitors in comparison with the universal IMF scenario, while the number of black hole progenitors remains unaffected.

scholarly journals Investigating accretion disk – radio jet coupling across the stellar mass scale

2010 ◽  
Vol 6 (S275) ◽  
pp. 224-232
Author(s):  
James C. A. Miller-Jones ◽  
Gregory R. Sivakoff ◽  
Diego Altamirano ◽  
Elmar G. Körding ◽  
Hans A. Krimm ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
White Dwarf ◽  
Angular Resolution ◽  
Stellar Mass ◽  
Mass Scale ◽  
High Angular Resolution ◽  
Jet Formation ◽  
X Ray ◽  
X Ray Binaries

AbstractRelationships between the X-ray and radio behavior of black hole X-ray binaries during outbursts have established a fundamental coupling between the accretion disks and radio jets in these systems. I begin by reviewing the prevailing paradigm for this disk-jet coupling, also highlighting what we know about similarities and differences with neutron star and white dwarf binaries. Until recently, this paradigm had not been directly tested with dedicated high-angular resolution radio imaging over entire outbursts. Moreover, such high-resolution monitoring campaigns had not previously targetted outbursts in which the compact object was either a neutron star or a white dwarf. To address this issue, we have embarked on the Jet Acceleration and Collimation Probe Of Transient X-Ray Binaries (JACPOT XRB) project, which aims to use high angular resolution observations to compare disk-jet coupling across the stellar mass scale, with the goal of probing the importance of the depth of the gravitational potential well, the stellar surface and the stellar magnetic field, on jet formation. Our team has recently concluded its first monitoring series, including (E)VLA, VLBA, X-ray, optical, and near-infrared observations of entire outbursts of the black hole candidate H 1743-322, the neutron star system Aquila X-1, and the white dwarf system SS Cyg. Here I present preliminary results from this work, largely confirming the current paradigm, but highlighting some intriguing new behavior, and suggesting a possible difference in the jet formation process between neutron star and black hole systems.

scholarly journals What can we learn from GRBs?

2018 ◽  
Vol 168 ◽  
pp. 01015
Author(s):  
Marco Muccino ◽  
Remo Ruffini ◽  
Yerlan Aimuratov ◽  
Laura M. Becerra ◽  
Carlo L. Bianco ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Binary System ◽  
Gravitational Collapse ◽  
White Dwarf ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Binary Nature ◽  
Accretion Process

We review our recent results on the classification of long and short gamma-ray bursts (GRBs) in different subclasses. We provide observational evidences for the binary nature of GRB progenitors. For long bursts the induced gravitational collapse (IGC) paradigm proposes as progenitor a tight binary system composed of a carbon-oxygen core (COcore) and a neutron star (NS) companion; the supernova (SN) explosion of the COcore triggers a hypercritical accretion process onto the companion NS. For short bursts a NS–NS merger is traditionally adopted as the progenitor. We also indicate additional sub-classes originating from different progenitors: (COcore)–black hole (BH), BH–NS, and white dwarf–NS binaries. We also show how the outcomes of the further evolution of some of these sub-classes may become the progenitor systems of other sub-classes.

The Development of a Black Hole—The Oppenheimer-Snyder Dust Cloud

1972 ◽  
Vol 2 (2) ◽  
pp. 110-111
Author(s):  
P. Szekeres
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Neutron Star ◽  
Gravitational Collapse ◽  
White Dwarf ◽  
Physical Mechanism ◽  
Critical Radius ◽  
Dust Cloud ◽  
Schwarzschild Solution

When a star of mass ≳ 2M⊙ collapses there does not appear to exist any physical mechanism to prevent total gravitational collapse, unless in some miraculous way the star always manages to blow off enough mass for it to settle down into a stable neutron star or white dwarf configuration. General relativity is needed in order to handle the ultimate situation, and the theory predicts a critical radius ρ = 2m (in units such that G = c = 1) at which the coordinates in the Schwarzschild solutionbecome invalid.

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