scholarly journals Plasma environment effects on K lines of astrophysical interest

2020 ◽  
Vol 643 ◽  
pp. A57
Author(s):  
J. Deprince ◽  
M. A. Bautista ◽  
S. Fritzsche ◽  
J. A. García ◽  
T. R. Kallman ◽  
...  
Keyword(s):  
Accretion Disks ◽  
Compact Object ◽  
Plasma Electron ◽  
Compact Objects ◽  
Emission Rates ◽  
Plasma Environment ◽  
Environment Effects ◽  
Decay Parameters ◽  
Threshold Energies ◽  
Fe Ions

Aims. Within the framework of compact-object accretion disks, we calculate plasma environment effects on the atomic structure and decay parameters used in the modeling of K lines in lowly charged iron ions, namely Fe II–Fe VIII. Methods. For this study, we used the fully relativistic multiconfiguration Dirac–Fock method approximating the plasma electron–nucleus and electron-electron screenings with a time-averaged Debye-Hückel potential. Results. We report modified ionization potentials, K-threshold energies, wavelengths, radiative emission rates, and Auger widths for plasmas characterized by electron temperatures and densities in the ranges 105 − 107 K and 1018 − 1022 cm−3. In addition, we propose two universal fitting formulae to predict the IP and K-threshold lowerings in any elemental ion. Conclusions. We conclude that the high-resolution X-ray spectrometers onboard the future XRISM and ATHENA space missions will be able to detect the lowering of the K edges of these Fe ions due to the extreme plasma conditions occurring in the accretion disks around compact objects.

scholarly journals Plasma-environment effects on K lines of astrophysical interest

2020 ◽  
Vol 635 ◽  
pp. A70
Author(s):  
J. Deprince ◽  
M. A. Bautista ◽  
S. Fritzsche ◽  
J. A. García ◽  
T. R. Kallman ◽  
...  
Keyword(s):  
Accretion Disks ◽  
Plasma Electron ◽  
Compact Objects ◽  
Emission Rates ◽  
Plasma Environment ◽  
Black Hole Accretion ◽  
Environment Effects ◽  
Threshold Energies ◽  
Hole Accretion ◽  
Atomic Parameters

Aims. In the context of black-hole accretion disks, we aim to compute the plasma-environment effects on the atomic parameters used to model the decay of K-vacancy states in moderately charged iron ions, namely Fe IX – Fe XVI. Methods. We used the fully relativistic multiconfiguration Dirac–Fock method approximating the plasma electron–nucleus and electron–electron screenings with a time-averaged Debye–Hückel potential. Results. We report modified ionization potentials, K-threshold energies, wavelengths, radiative emission rates, and Auger widths for plasmas characterized by electron temperatures and densities in the ranges 105−107 K and 1018−1022 cm−3. Conclusions. This study confirms that the high-resolution X-ray spectrometers onboard the future XRISM and Athena space missions will be capable of detecting the lowering of the K edges of these ions due to the extreme plasma conditions occurring in accretion disks around compact objects.

scholarly journals Plasma environment effects on K lines of astrophysical interest

2019 ◽  
Vol 626 ◽  
pp. A83 ◽  
Author(s):  
J. Deprince ◽  
M. A. Bautista ◽  
S. Fritzsche ◽  
J. A. García ◽  
T. Kallman ◽  
...  
Keyword(s):  
Accretion Disks ◽  
Electron Plasma ◽  
Compact Objects ◽  
Emission Rates ◽  
Astrophysical Plasmas ◽  
X Ray ◽  
Radiative Emission ◽  
Plasma Environment ◽  
Environment Effects ◽  
Atomic Parameters

Aims. In the context of accretion disks around black holes, we estimate plasma-environment effects on the atomic parameters associated with the decay of K-vacancy states in highly charged iron ions, namely Fe XVII – Fe XXV. Methods. Within the relativistic multiconfiguration Dirac–Fock (MCDF) framework, the electron–nucleus and electron–electron plasma screenings were approximated with a time-averaged Debye–Hückel potential. Results. Modified ionization potentials, K thresholds, wavelengths, radiative emission rates, and Auger widths are reported for astrophysical plasmas characterized by electron temperatures and densities in the ranges 105 − 107 K and 1018 − 1022 cm−3, respectively. Conclusions. We conclude that the high-resolution microcalorimeters on board future X-ray missions such as XRISM and ATHENA are expected to be sensitive to the lowering of the iron K edge due to the extreme plasma conditions occurring in accretion disks around compact objects.

scholarly journals Plasma environment effects on K lines of astrophysical interest

2019 ◽  
Vol 624 ◽  
pp. A74 ◽  
Author(s):  
J. Deprince ◽  
M. A. Bautista ◽  
S. Fritzsche ◽  
J. A. García ◽  
T. R. Kallman ◽  
...  
Keyword(s):  
Black Hole ◽  
Electron Temperature ◽  
Accretion Disks ◽  
Atomic Structure ◽  
Radiative Transition ◽  
Ionization Potentials ◽  
Plasma Environment ◽  
Black Hole Accretion ◽  
Environment Effects ◽  
Hole Accretion

Aims. In the context of black-hole accretion disks, the main goal of the present study is to estimate the plasma environment effects on the atomic structure and radiative parameters associated with the K-vacancy states in ions of the oxygen isonuclear sequence. Methods. We used a time-averaged Debye–Hückel potential for both the electron–nucleus and the electron–electron interactions implemented in the fully relativistic multiconfiguration Dirac–Fock (MCDF) method. Results. Modified ionization potentials, K thresholds, Auger widths, and radiative transition wavelengths and rates are reported for O I–O VII in plasma environments with electron temperature and density ranges 105−107 K and 1018−1022 cm−3.

scholarly journals Pulsational Instability of Accretion Disks around Compact Objects

1993 ◽  
Vol 134 ◽  
pp. 361-364
Author(s):  
T. Okuda ◽  
S. Mineshige
Keyword(s):  
Accretion Disks ◽  
Cataclysmic Variables ◽  
Compact Object ◽  
Linear Analysis ◽  
Compact Objects ◽  
Periodic Oscillations ◽  
X Ray ◽  
Axisymmetric Perturbation ◽  
Low Mass ◽  
X Ray Binaries

AbstractLinear analysis shows that radial oscillations in accretion disks around compact object are overstable to axisymmetric perturbation under a variety of conditions. Furthermore, numerical simulations confirm that the radial oscillations induce quasi-periodic modulations of the disk luminosity. The disk oscillation model may be responsible for quasi-periodic oscillations (QPOs) observed in low mass X-ray binaries (LMXBs), cataclysmic variables (CVs), and other compact objects.

scholarly journals Luminosity of accretion disks in compact objects with a quadrupole

2021 ◽  
Vol 104 (8) ◽  
Author(s):  
Kuantay Boshkayev ◽  
Talgar Konysbayev ◽  
Ergali Kurmanov ◽  
Orlando Luongo ◽  
Daniele Malafarina ◽  
...  
Keyword(s):  
Accretion Disks ◽  
Compact Objects

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.

scholarly journals Accretion onto Relativistic Objects

1974 ◽  
Vol 64 ◽  
pp. 194-212
Author(s):  
M. J. Rees
Keyword(s):  
Black Holes ◽  
Interstellar Medium ◽  
Neutron Stars ◽  
Binary Systems ◽  
Compact Object ◽  
Stellar Mass ◽  
Supermassive Black Holes ◽  
Compact Objects ◽  
X Ray ◽  
Intergalactic Space

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.

scholarly journals Effect of Compact Objects Near Be Stars

1987 ◽  
Vol 92 ◽  
pp. 516-518
Author(s):  
Krishna M.V. Apparao ◽  
S.P. Tarafdar
Keyword(s):  
Black Holes ◽  
Neutron Star ◽  
Rotation Period ◽  
Compact Object ◽  
Compact Objects ◽  
X Rays ◽  
Be Stars ◽  
Eccentric Orbit ◽  
X Ray ◽  
Be Star

Several Be stars are identified with bright X-ray sources. (Rappaport and Van den Heuvel, 1982). The bright X-ray emission and observed periodicities indicate the existence of compact objects (white dwarfs, neutron stars or black holes) near the Be stars. A prime example is the brightest X-ray source A0538-66 in LMC, which contains a neutron star with a rotation period of 59 ms. Apparao (1985) explained the X-ray emission, which occurs in periodic flares, by considering an inclined eccentric orbit for the neutron star around the assumed Be-star. The neutron star when it enters a gas ring (around the Be-star) accreting matter giving out X-rays.The X-ray emission from the compact objects, when the gas ring from the Be-star envelopes the objects, has interesting consequences. The X-ray emission produces an ionized region (compact object Stromgren sphere or COSS) in the gas surrounding the compact object (CO).

scholarly journals Wind Accretion by Compact Objects: The “Flip-Flop” Instability

1992 ◽  
Vol 151 ◽  
pp. 185-194
Author(s):  
Mario Livio
Keyword(s):  
Random Walk ◽  
Accretion Rate ◽  
Compact Object ◽  
Two Dimensions ◽  
Compact Objects ◽  
Numerical Calculations ◽  
Three Dimensions ◽  
Flip Flop ◽  
Accretion Flows ◽  
The Stability

The problem of the stability of wind accretion onto compact objects is examined. Recent analytical and numerical calculations show that in two dimensions, Bondi-Hoyle accretion flows are unstable to a “flip-flop” instability. The instability can manifest itself as bursts in the accretion rate and as a random walk-type spin-up, spin-down behaviour of the accreting compact object. The nature of the flow in three dimensions needs further clarification. Possible observational implications are reviewed.

scholarly journals Two-Dimensional Accretion Disk Models of a Neutron Star

1998 ◽  
Vol 188 ◽  
pp. 374-375
Author(s):  
M. Fujita ◽  
T. Okuda
Keyword(s):  
Neutron Star ◽  
Electron Scattering ◽  
Radiation Transport ◽  
Compact Object ◽  
Compact Objects ◽  
High Mass ◽  
Two Dimensional ◽  
Accretion Rates ◽  
The Difference ◽  
Characteristic Features

We investigate the accretion disks around compact objects with high mass accretion rates near the Eddington's critical value ME, where radiation pressure and electron scattering are dominant. This raises next problems: (a) whether stable disks could exist in relation to the theory of thermal instabilities of the disk and (b) what characteristic features the disks have if the stable disks exist. A non-rotating neutron star with the mass M = 1.4M⊙, radius R* = 107cm and the accretion rate Mac = 2.0 and 0.5Mac (models 1 and 2) is considered as the compact object. We assume the α-model for the viscosity and solve the set of two-dimensional time-dependent hydrodynamic equations coupled with radiation transport. The numerical method used is basically the same as one described by Kley and Hensler (1987) and Kley (1989) but we include some improvements in solving the difference equations (Okuda et al. 1997). The initial configuration consists of a cold, dense, and optically thick disk which is given by the standard α-model (Shakura and Sunyaev 1973) and a rarefied optically thin atmosphere around the disk.

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