Spectral properties of shocked accretion flows— a self-consistent study

2007 ◽  
pp. 163-166
Author(s):  
Sandip K. Chakrabarti ◽  
Samir Mandal
Keyword(s):  
Spectral Properties ◽  
Accretion Flows ◽  
Self Consistent

Spectral properties of shocked accretion flows— a self-consistent study

2007 ◽  
Vol 309 (1-4) ◽  
pp. 163-166 ◽  
Author(s):  
Sandip K. Chakrabarti ◽  
Samir Mandal
Keyword(s):  
Spectral Properties ◽  
Accretion Flows ◽  
Self Consistent

scholarly journals Many-impurity scattering on the surface of a topological insulator

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
José Luis Hernando ◽  
Yuriko Baba ◽  
Elena Díaz ◽  
Francisco Domínguez-Adame
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Topological Insulator ◽  
Disordered Systems ◽  
Spectral Properties ◽  
Random Distribution ◽  
Surface States ◽  
Impurity Scattering ◽  
Self Consistent ◽  
The Impact

AbstractWe theoretically address the impact of a random distribution of non-magnetic impurities on the electron states formed at the surface of a topological insulator. The interaction of electrons with the impurities is accounted for by a separable pseudo-potential method that allows us to obtain closed expressions for the density of states. Spectral properties of surface states are assessed by means of the Green’s function averaged over disorder realisations. For comparison purposes, the configurationally averaged Green’s function is calculated by means of two different self-consistent methods, namely the self-consistent Born approximation (SCBA) and the coherent potential approximation (CPA). The latter is often regarded as the best single-site theory for the study of the spectral properties of disordered systems. However, although a large number of works employ the SCBA for the analysis of many-impurity scattering on the surface of a topological insulator, CPA studies of the same problem are scarce in the literature. In this work, we find that the SCBA overestimates the impact of the random distribution of impurities on the spectral properties of surface states compared to the CPA predictions. The difference is more pronounced when increasing the magnitude of the disorder.

scholarly journals Magnetar X-ray emission mechanisms

2012 ◽  
Vol 8 (S291) ◽  
pp. 160-160
Author(s):  
Silvia Zane
Keyword(s):  
Spectral Analysis ◽  
Physical Interpretation ◽  
Spectral Properties ◽  
Gamma Ray ◽  
X Ray ◽  
Spectral Components ◽  
Self Consistent ◽  
Photon Index ◽  
Index 2 ◽  
Surface Fields

AbstractSoft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are peculiar X-ray sources which are believed to be magnetars: ultra-magnetized neutron stars which emission is dominated by surface fields (often in excess of 1E14 G, i.e. well above the QED threshold).Spectral analysis is an important tool in magnetar astrophysics since it can provide key information on the emission mechanisms. The first attempts at modelling the persistent (i.e. outside bursts) soft X-ray (¡10 keV) spectra of AXPs proved that a model consisting of a blackbody (kT 0.3-0.6 keV) plus a power-law (photon index 2-4) could successfully reproduce the observed emission. Moreover, INTEGRAL observations have shown that, while in quiescence, magnetars emit substantial persistent radiation also at higher energies, up to a few hundreds of keV. However, a convincing physical interpretation of the various spectral components is still missing.In this talk I will focus on the interpretation of magnetar spectral properties during quiescence. I will summarise the present status of the art and the currents attempts to model the broadband persistent emission of magnetars (from IR to hard Xrays) within a self consistent, physical scenario.

scholarly journals A charge self-consistent LDA+DMFT study of the spectral properties of hexagonal NiS

2014 ◽  
Vol 16 (9) ◽  
pp. 093049 ◽  
Author(s):  
S K Panda ◽  
P Thunström ◽  
I Di Marco ◽  
J Schött ◽  
A Delin ◽  
...  
Keyword(s):  
Spectral Properties ◽  
Self Consistent ◽  
A Charge

scholarly journals Self-consistent approach for spectral properties of single alkali adatoms on Cu(111)

2012 ◽  
Vol 85 (4) ◽  
Author(s):  
S. Achilli ◽  
M. I. Trioni ◽  
E. V. Chulkov
Keyword(s):  
Spectral Properties ◽  
Self Consistent ◽  
Consistent Approach

Clumpy accretion flows in active galactic nuclei: X-ray variability and spectral properties

2010 ◽  
Author(s):  
W. Ishibashi ◽  
T. J.-L. Courvoisier ◽  
A. Comastri ◽  
L. Angelini ◽  
M. Cappi
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
X Ray ◽  
Accretion Flows

scholarly journals Unified Accretion Disk Models Around Black Holes and Neutron Stars and Their Spectral Properties

1997 ◽  
Vol 163 ◽  
pp. 427-438
Author(s):  
S. K. Chakrabarti
Keyword(s):  
Spectral Properties ◽  
Ad Hoc ◽  
Compact Objects ◽  
Density Region ◽  
Periodic Oscillations ◽  
X Ray ◽  
Accretion Flows ◽  
Supermassive Black Hole ◽  
Low Mass ◽  
High Density Region

AbstractWe review the current understanding of accretion flows around compact objects with a special emphasis on advective disks. We discuss the influence of the centrifugal pressure supported high density region around compact objects (where shocks may also form) on the emitted spectra. We show that the stationary and non-stationary spectral properties (such as, low and high states, transition of states, quasi-periodic oscillations, quiescent and rising phases of X-ray novae, etc.) of both low mass and supermassive black hole candidates could be satisfactorily explained within the framework of the analytical solution of the advective disks without invoking any ad hoc components such as Compton clouds or magnetic corona.

scholarly journals Radiation from Advection-Dominated Flows

1998 ◽  
Vol 188 ◽  
pp. 417-418
Author(s):  
T. Manmoto
Keyword(s):  
Black Holes ◽  
Compact Objects ◽  
Radiation Process ◽  
Massive Black Hole ◽  
Accretion Flow ◽  
Accretion Flows ◽  
Accretion Process ◽  
Self Consistent ◽  
Consistent Solution ◽  
Sgr A

Advection-dominated accretion flow (hereafter ADAF) is the only self-consistent solution to describe the optically thin accretion flows around compact objects. The main feature of ADAF is that the dynamics of the flow is dominated by accretion process rather than radiation process. As a result of advection domination, the luminosity of ADAFs is very low. Coupled with the existence of the event horizon, ADAF has been successfully applied to the dim accretion black holes such as central core of our Galaxy: Sgr A*. In this issue, we calculate the spectrum radiated from the optically thin ADAFs and show that the observed spectrum of Sgr A* is explained with the accretion massive black hole.

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