Soft X-ray emission lines from low-mass X-ray binaries. I - Collision-dominated models

1989 ◽  
Vol 345 ◽  
pp. 498 ◽  
Author(s):  
T. R. Kallman ◽  
S. D. Vrtilek ◽  
S. M. Kahn
Keyword(s):  
X Ray ◽  
Low Mass ◽  
2000 ◽  
Vol 131 (2) ◽  
pp. 571-591 ◽  
Author(s):  
K. Asai ◽  
T. Dotani ◽  
F. Nagase ◽  
K. Mitsuda

2008 ◽  
Vol 674 (1) ◽  
pp. 415-420 ◽  
Author(s):  
Edward M. Cackett ◽  
Jon M. Miller ◽  
Sudip Bhattacharyya ◽  
Jonathan E. Grindlay ◽  
Jeroen Homan ◽  
...  

1994 ◽  
Vol 431 ◽  
pp. 273 ◽  
Author(s):  
Yuan-Kuen Ko ◽  
Timothy R. Kallman

1995 ◽  
Vol 163 ◽  
pp. 245-247
Author(s):  
V.S. Niemela ◽  
R.H. Barbá ◽  
M.M. Shara

Spectral observations of the WN3p star WR46 (HD 104994) obtained during June 1993 and January/February 1994 display large amplitude radial velocity variations of the strong emission lines Nv 4603-19Å and HeII 4686A, on a time scale of a fraction of a day. The most probable period found is 0.311 d, similar to the photometric period found by previous authors. The amplitude of the radial velocity variations of Nv emission is almost twice that of HeII. Noting the similarity of WR46 with low mass X-ray binaries, we suggest that the emission line spectrum corresponds to that of a luminous accretion disk in an evolved binary system.


2008 ◽  
Vol 690 (2) ◽  
pp. 1847-1855 ◽  
Author(s):  
E. M. Cackett ◽  
J. M. Miller ◽  
J. Homan ◽  
M. van der Klis ◽  
W. H. G. Lewin ◽  
...  

2018 ◽  
Vol 620 ◽  
pp. A129 ◽  
Author(s):  
I. Psaradaki ◽  
E. Costantini ◽  
M. Mehdipour ◽  
M. Díaz Trigo

Low mass X-ray binaries exhibit ionized emission from an extended disc atmosphere that surrounds the accretion disc. However, the atmosphere’s nature and geometry is still unclear. In this work we present a spectral analysis of the extended atmosphere of EXO 0748-676 using high-resolution spectra from archival XMM-Newton observations. We model the spectrum that is obtained during the eclipses. This enables us to model the emission lines that come only from the extended atmosphere of the source, and study its physical structure and properties. The RGS spectrum reveals a series of emission lines consistent with transitions of OVIII, OVII, NeIX and NVII. We perform both Gaussian line fitting and photoionization modelling. Our results suggest that there are two photoionization gas components that are out of pressure equilibrium with respect to each other. One has an ionization parameter of log ξ ∼ 2.5 and a large opening angle, and one has log ξ ∼ 1.3. The second component possibly covers a smaller fraction of the source. From the density diagnostics of the OVII triplet using photoionization modelling, we detect a rather high density plasma of > 1013 cm−3 for the lower ionization component. This latter component also displays an inflow velocity. We propose a scenario where the high ionization component constitutes an extended upper atmosphere of the accretion disc. The lower ionization component may instead be a clumpy gas created from the impact of the accretion stream with the disc.


2012 ◽  
Vol 755 (1) ◽  
pp. 27 ◽  
Author(s):  
Edward M. Cackett ◽  
Jon M. Miller ◽  
Rubens C. Reis ◽  
Andrew C. Fabian ◽  
Didier Barret

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.


Author(s):  
Nicolas Scepi ◽  
Mitchell C Begelman ◽  
Jason Dexter

Abstract Dwarf novæ (DNe) and low mass X-ray binaries (LMXBs) are compact binaries showing variability on time scales from years to less than seconds. Here, we focus on explaining part of the rapid fluctuations in DNe, following the framework of recent studies on the monthly eruptions of DNe that use a hybrid disk composed of an outer standard disk and an inner magnetized disk. We show that the ionization instability, that is responsible for the monthly eruptions of DNe, is also able to operate in the inner magnetized disk. Given the low density and the fast accretion time scale of the inner magnetized disk, the ionization instability generates small, rapid heating and cooling fronts propagating back and forth in the inner disk. This leads to quasi-periodic oscillations (QPOs) with a period of the order of 1000 s. A strong prediction of our model is that these QPOs can only develop in quiescence or at the beginning/end of an outburst. We propose that these rapid fluctuations might explain a subclass of already observed QPOs in DNe as well as a, still to observe, subclass of QPOs in LMXBs. We also extrapolate to the possibility that the radiation pressure instability might be related to Type B QPOs in LMXBs.


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