GINGA OBSERVATIONS OF X0512–401 IN THE GLOBULAR CLUSTER NGC1851

1993 ◽  
Vol 02 (04) ◽  
pp. 497-507
Author(s):  
E.N. ERCAN ◽  
A.M. CRUISE ◽  
B.J. KELLETT
Keyword(s):  
Neutron Star ◽  
Emission Line ◽  
Accretion Disk ◽  
Power Law ◽  
Globular Cluster ◽  
Third Body ◽  
X Ray ◽  
Two Component ◽  
Low Mass ◽  
Best Fit

We present here the first detailed spectral observations of the low-mass X-ray binary source X0512–401 located in the globular cluster NGC1851 obtained by Ginga. We have found that the Ginga LAC data of X0512–401 are best fitted by a “two-component” spectral model: power-law with exponential cut-off and a blackbody. The inclusion of a 6.7 KeV Fe emission line did not improve our best fit. In the light of the present observations and the previous studies concerning the importance of Comptonization, our model requires a scattering cloud surrounding the neutron star, with a Thomson optical depth of ~5. The detection of ~30–40 hr periodicity is hard to interpret in terms of the possible binary period of the system, since most of these systems have binary periods of a few hours or even less. It may either suggest that the accretion disk around the neutron star is precessing or there is a third body in the system.

scholarly journals Hardness Ratio in Evolving Low-Mass X-ray Binary Systems

1987 ◽  
Vol 125 ◽  
pp. 199-199
Author(s):  
J. Shaham ◽  
M. Tavani
Keyword(s):  
Neutron Star ◽  
Accretion Disk ◽  
Binary Systems ◽  
Spectral Component ◽  
Soft Component ◽  
Hard Component ◽  
X Ray ◽  
Low Mass ◽  
Additional Support ◽  
X Ray Binaries

Spectral observations of low-mass X-ray binaries (LMXBs) show that the soft component usually dominates over the hard one. These results provide additional support to an interpretation based on models of LMXBs in which the neutron star while, on the average, spinning up, is also experiencing a spinning down torque. Under these conditions, a fraction of the luminosity associated with the gravitational release of energy on the surface of the accreting neutron star may manifest itself as luminosity originating in the inner part of the accretion disk. It is probably possible to separate the two contributions; the stellar luminosity can be associated with the hard component of the spectrum and the disk luminosity, related to the exchange of energy due to the torque between the rapidly spinning neutron star and the accretion disk, can be associated with the soft spectral component.

scholarly journals Neutron star atmosphere composition: the quiescent, low-mass X-ray binary in the globular cluster M28

2012 ◽  
Vol 423 (2) ◽  
pp. 1556-1561 ◽  
Author(s):  
M. Servillat ◽  
C. O. Heinke ◽  
W. C. G. Ho ◽  
J. E. Grindlay ◽  
J. Hong ◽  
...  
Keyword(s):  
Neutron Star ◽  
Globular Cluster ◽  
X Ray ◽  
Atmosphere Composition ◽  
Low Mass

scholarly journals A relativistic iron emission line from the neutron star low-mass X-ray binary GX 3+1

2012 ◽  
Vol 542 ◽  
pp. L27 ◽  
Author(s):  
S. Piraino ◽  
A. Santangelo ◽  
P. Kaaret ◽  
B. Mück ◽  
A. D’Aì ◽  
...  
Keyword(s):  
Neutron Star ◽  
Emission Line ◽  
X Ray ◽  
Low Mass

scholarly journals Detection of millihertz quasi-periodic oscillations in the X-Ray binary 1RXS J180408.9−342058

2020 ◽  
Vol 500 (1) ◽  
pp. 34-39
Author(s):  
Kaho Tse ◽  
Duncan K Galloway ◽  
Yi Chou ◽  
Alexander Heger ◽  
Hung-En Hsieh
Keyword(s):  
Neutron Star ◽  
Power Law ◽  
Numerical Models ◽  
Periodic Oscillations ◽  
X Ray ◽  
Thermonuclear Burning ◽  
Low Mass ◽  
Power Law Noise ◽  
Star Surface ◽  
X Ray Binaries

ABSTRACT Millihertz quasi-periodic oscillations (mHz QPOs) observed in neutron-star low-mass X-ray binaries (NS LMXBs) are generally explained as marginally stable thermonuclear burning on the neutron star surface. We report the discovery of mHz QPOs in an XMM–Newton observation of the transient 1RXS J180408.9−342058, during a regular bursting phase of its 2015 outburst. We found significant periodic signals in the March observation, with frequencies in the range 5–8 $\, \mathrm{mHz}$, superimposed on a strong ∼1/f power-law noise continuum. Neither the QPO signals nor the power-law noise were present during the April observation, which exhibited a 2.5 × higher luminosity and had correspondingly more frequent bursts. When present, the QPO signal power decreases during bursts and disappears afterwards, similar to the behaviour in other sources. 1RXS J180408.9−342058 is the eighth source known to date that exhibits such QPOs driven by thermonuclear burning. We examine the range of properties of the QPO signals in different sources. Whereas the observed oscillation profile is similar to that predicted by numerical models, the amplitudes are significantly higher, challenging their explanation as originating from marginally stable burning.

scholarly journals NEUTRON STAR MASS–RADIUS CONSTRAINTS OF THE QUIESCENT LOW-MASS X-RAY BINARIES X7 AND X5 IN THE GLOBULAR CLUSTER 47 TUC

2016 ◽  
Vol 831 (2) ◽  
pp. 184 ◽  
Author(s):  
Slavko Bogdanov ◽  
Craig O. Heinke ◽  
Feryal Özel ◽  
Tolga Güver
Keyword(s):  
Neutron Star ◽  
Globular Cluster ◽  
X Ray ◽  
Star Mass ◽  
Neutron Star Mass ◽  
Low Mass ◽  
X Ray Binaries

scholarly journals Truncation of the Accretion Disk at One-third of the Eddington Limit in the Neutron Star Low-mass X-Ray Binary Aquila X-1

2017 ◽  
Vol 847 (2) ◽  
pp. 135 ◽  
Author(s):  
R. M. Ludlam ◽  
J. M. Miller ◽  
N. Degenaar ◽  
A. Sanna ◽  
E. M. Cackett ◽  
...  
Keyword(s):  
Neutron Star ◽  
Accretion Disk ◽  
X Ray ◽  
Low Mass ◽  
Eddington Limit

scholarly journals X-ray spectroscopy of newly identified ULXs associated with M87’s globular cluster population

2020 ◽  
Vol 497 (1) ◽  
pp. 596-608 ◽  
Author(s):  
Kristen C Dage ◽  
Stephen E Zepf ◽  
Erica Thygesen ◽  
Arash Bahramian ◽  
Arunav Kundu ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Component Model ◽  
X Ray ◽  
Two Component ◽  
Long Time ◽  
Order Of Magnitude ◽  
Best Fitting ◽  
Component Models ◽  
Best Fit

ABSTRACT We have identified seven ultraluminous X-ray sources (ULXs) that are coincident with globular cluster candidates (GC) associated with M87. ULXs in the old GC environment represent a new population of ULXs, and ones likely to be black holes. In this study, we perform detailed X-ray spectroscopic follow-up to seven GC ULXs across a wealth of archival Chandra observations and long time baseline of 16 yr. This study brings the total known sample of GC ULXs to 17. Two of these sources show variability in their X-ray luminosity of an order of magnitude over many years, and one of these sources shows intra-observational variability on the scale of hours. While the X-ray spectra of the majority of GC ULXs are best fit by single-component models, one of the sources studied in this paper is the second GC ULX to be best fit by a two-component model. We compare this new sample of GC ULXs to the previously studied sample, and compare the X-ray and optical properties counterparts across the samples. We find that the clusters that host ULXs in M87 have metallicities from g − z = 1.01 to g − z = 1.70. The best-fitting power-law indices of the X-ray spectra range from Γ = 1.37 to 2.21, and the best-fitting inner blackbody disc temperatures range from kT = 0.56 to 1.90 keV.

scholarly journals DISC ATMOSPHERES AND WINDS IN X-RAY BINARIES

2013 ◽  
Vol 53 (A) ◽  
pp. 659-664 ◽  
Author(s):  
Maria Díaz Trigo ◽  
Laurence Boirin
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Emission Line ◽  
Current Status ◽  
X Ray ◽  
Black Hole Binaries ◽  
Low Mass ◽  
X Ray Binaries ◽  
Radiative Pressure

We review the current status of studies of disc atmospheres and winds in low mass X-ray binaries. We discuss the possible wind launching mechanisms and compare the predictions of the models with the existent observations. We conclude that a combination of thermal and radiative pressure (the latter being relevant at high luminosities) can explain the current observations of atmospheres and winds in both neutron star and black hole binaries. Moreover, these winds and atmospheres could contribute significantly to the broad iron emission line observed in these systems.

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.

4U 1608–52 as a quasi-persistent X-ray source

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Vojtěch Šimon
Keyword(s):  
Accretion Disk ◽  
Time Segment ◽  
X Ray ◽  
Band Emission ◽  
Heating And Cooling ◽  
Soft State ◽  
Cyclic Variations ◽  
Low Mass ◽  
X Ray Binaries ◽  
Disk Region

Abstract 4U 1608–52 is a soft X-ray transient. The analysis presented here of a particular part of its X-ray activity uses observations of RXTE/ASM and Swift/BAT. We show a time segment (MJD 54262–MJD 55090) (828 d) in which 4U 1608–52 behaved as a quasi-persistent X-ray source with a series of bumps, with a complicated relation between the evolution of fluxes in the soft (1.5–12 keV) and the hard (15–50 keV) X-ray regions. We ascribe these bumps to a series of propagations of heating and cooling fronts over the inner disk region without any transitions to the true quiescence. 4U 1608–52 oscillated around the boundary between the dominance of the Comptonized component and the dominance of the multicolor accretion disk in its luminosity. Only some of the bumps in this series were accompanied by a transition from the hard to the soft state; if it occurred, it displayed a strong hysteresis effect. The hard-band emission with the dominant Comptonized component was present for most of this active state and showed a cycle of about 40 d. We argue that the cyclic variations of flux come from the inner disk region, not, e.g., from a jet. We also discuss the observed behavior of 4U 1608–52 in the context of other quasi-persistent low-mass X-ray binaries.

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