scholarly journals Short term aperiodic variability of X-ray binaries: its origin and implications

2008 ◽  
Author(s):  
Mikhail Revnivtsev ◽  
Magnus Axelsson
Keyword(s):  
Short Term ◽  
X Ray ◽  
X Ray Binaries

scholarly journals Generation of X-Ray Fluctuations in X-Ray Binaries

1996 ◽  
Vol 158 ◽  
pp. 359-362
Author(s):  
S. Mineshige ◽  
M. Takeuchi ◽  
H. Negoro
Keyword(s):  
Accretion Disks ◽  
Mass Density ◽  
Temporal Distribution ◽  
Critical Value ◽  
Short Term ◽  
X Ray ◽  
Self Organized ◽  
Power Spectral ◽  
Self Organized Criticality ◽  
X Ray Binaries

AbstractShort-term aperiodic fluctuations with 1/f-like power spectral density (PSD), where f is the frequency, are characteristics of X-ray radiation from X-ray binaries. To investigate a mechanism creating fluctuations, we construct a cellular-automaton model for accretion disks based on the concept of self organized criticality (SOC). In this model, mass accretion takes place either by an avalanche triggered when the local mass density exceeds some critical value, or by a gradual diffusion occurring regardless of the critical condition. With this model, we can reproduce the observational PSD, the distributions of peak intensities of X-ray shots, and non-random temporal distribution of the shots. Possible accretion disk models producing l/f-like X-ray fluctuations are discussed. We conclude that such disks are likely to be advection dominated.

scholarly journals Non-radial pulsations in the Be/X binaries 4U 0115+63 and SAX J2103.5+4545

2010 ◽  
Vol 6 (S272) ◽  
pp. 505-506
Author(s):  
Juan Gutiérrez-Soto ◽  
Pablo Reig ◽  
Juan Fabregat ◽  
Lester Fox-Machado
Keyword(s):  
Complex Systems ◽  
Magellanic Clouds ◽  
Short Term ◽  
New Approach ◽  
X Ray ◽  
Preliminary Results ◽  
Stellar Pulsations ◽  
X Ray Binaries ◽  
Radial Pulsations ◽  
Short Term Variability

AbstractThe discovery of non-radial pulsations (NRP) in the Be/X binaries of the Magellanic Clouds (MC, eg. Fabrycky 2005, Coe et al. 2005, Schmidtke & Cowley 2005) provided a new approach to understand these complex systems, and, at the same time, favoured the synergy between two different fields: stellar pulsations and X-ray binaries. This breakthrough was possible thanks to the MACHO and OGLE surveys. However, in our Galaxy, only two Be/X have been reported to show NRP: GRO J2058+42 (Kiziloglu et al. 2007) and LSI+61 235 (Sarty et al. 2009). Our objective is to study the short-term variability of Galactic Be/X binaries, compare them to the Be/X of the MC and to the isolated Galactic Be observed with corot and kepler. We present preliminary results of two Be/X stars, namely 4U 0115+63 and SAX J2103.5+4545 showing multiperiodicity and periodicity respectively, most probable produced by NRP.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

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.

X-ray binaries

1990 ◽  
Vol 15 (1) ◽  
pp. 29-61
Author(s):  
J.-P. Lasota
Keyword(s):  
X Ray ◽  
X Ray Binaries

Polarization Variability of Active Galactic Nuclei and X‐Ray Binaries

1997 ◽  
Vol 487 (1) ◽  
pp. 142-152 ◽  
Author(s):  
Gang Bao ◽  
Petr Hadrava ◽  
Paul J. Wiita ◽  
Ying Xiong
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
X Ray Binaries

Lense‐Thirring Precession and Quasi‐periodic Oscillations in X‐Ray Binaries

1998 ◽  
Vol 507 (1) ◽  
pp. 316-326 ◽  
Author(s):  
Dragoljub Marković ◽  
Frederick K. Lamb
Keyword(s):  
Periodic Oscillations ◽  
X Ray ◽  
X Ray Binaries

scholarly journals X-Ray Determination of the Black-Hole Mass in Cygnus X-1

1998 ◽  
Vol 188 ◽  
pp. 388-389
Author(s):  
A. Kubota ◽  
K. Makishima ◽  
T. Dotani ◽  
H. Inoue ◽  
K. Mitsuda ◽  
...  
Keyword(s):  
Black Hole ◽  
Compact Object ◽  
Optical Observations ◽  
Black Hole Mass ◽  
X Ray ◽  
Upper Limit ◽  
Supergiant Star ◽  
X Ray Binaries ◽  
Two Bodies

About 10 X-ray binaries in our Galaxy and LMC/SMC are considered to contain black hole candidates (BHCs). Among these objects, Cyg X-1 was identified as the first BHC, and it has led BHCs for more than 25 years(Oda 1977, Liang and Nolan 1984). It is a binary system composed of normal blue supergiant star and the X-ray emitting compact object. The orbital kinematics derived from optical observations indicates that the compact object is heavier than ~ 4.8 M⊙ (Herrero 1995), which well exceeds the upper limit mass for a neutron star(Kalogora 1996), where we assume the system consists of only two bodies. This has been the basis for BHC of Cyg X-1.

scholarly journals GCT-08. PROTON BEAM RADIOTHERAPY FOR PEDIATRIC AND YOUNG-ADULT PATIENTS WITH INTRACRANIAL GERM CELL TUMOR

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii329-iii329
Author(s):  
Minako Sugiyama ◽  
Takayuki Hashimoto ◽  
Takashi Mori ◽  
Kazuya Hara ◽  
Yukayo Terashita ◽  
...  
Keyword(s):  
Young Adult ◽  
Adverse Events ◽  
Germ Cell ◽  
Cell Count ◽  
Proton Beam ◽  
Adult Patients ◽  
Short Term ◽  
Intracranial Germ Cell Tumor ◽  
X Ray ◽  
Proton Beam Radiotherapy

Abstract BACKGROUND To reduce treatment-related adverse events in pediatric and young-adult patients with brain tumors, proton beam radiotherapy (PBT) has recently been performed instead of conventional X-ray radiotherapy. However, whether PBT is as effective as X-ray radiotherapy has not been sufficiently investigated, especially in patients receiving whole-ventricular irradiation. METHODS We report a retrospective observation of 15 patients with intracranial germ cell tumors (GCT), who received PBT at our institution from April 2014 to September 2019. We evaluated their clinical course, short-term adverse events, and prognosis. RESULTS/ CONCLUSION Fifteen patients (9 males and 6 females; median age 13 years) who received PBT following induction chemotherapy were analyzed. Nine patients received 23.4–27.0 GyE of whole-ventricular irradiation due to GCT in the pituitary gland, pineal body, or hypothalamic area. Three patients received 23.4 GyE of whole-brain irradiation: one of them had boost irradiation for basal ganglia. Three patients received 30.6 GyE of craniospinal irradiation (CSI). Six of the 15 patients experienced nausea (grade 2, according to the CTCAE version 4.0). Four patients, including two who received CSI, showed myelosuppression: decrease in white blood cell count, lymphocyte cell count, and neutrophil count (grade 3). No other severe short-term adverse events of >grade 2 was observed in any of the patients. At a median follow-up of 21 months (2-62 months) after irradiation. all patients are alive without recurrence. Our results may be encouraging and further investigations with a larger scale is warranted.

scholarly journals QPOs in compact binaries from small scale eruptions in an inner magnetized disk

2020 ◽  
Author(s):  
Nicolas Scepi ◽  
Mitchell C Begelman ◽  
Jason Dexter
Keyword(s):  
Rapid Heating ◽  
Small Scale ◽  
Type B ◽  
Periodic Oscillations ◽  
X Ray ◽  
Compact Binaries ◽  
Heating And Cooling ◽  
Low Mass ◽  
X Ray Binaries ◽  
Standard Disk

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.

Sign in / Sign up

Export Citation Format

Share Document