scholarly journals Low-mass X-ray binaries: the effects of the magnetic braking prescription

2018 ◽  
Vol 483 (4) ◽  
pp. 5595-5613 ◽  
Author(s):  
K X Van ◽  
N Ivanova ◽  
C O Heinke
Keyword(s):  
X Ray ◽  
Low Mass ◽  
Magnetic Braking ◽  
X Ray Binaries

Constraining Progenitors of Observed Low-mass X-ray Binaries Using Convection and Rotation-Boosted Magnetic Braking

2021 ◽  
Vol 922 (2) ◽  
pp. 174
Author(s):  
Kenny X. Van ◽  
Natalia Ivanova
Keyword(s):  
Mass Transfer ◽  
Binary Systems ◽  
Formation Rate ◽  
Mass Transfer Rate ◽  
Population Synthesis ◽  
X Ray ◽  
Synthesis Technique ◽  
Low Mass ◽  
Magnetic Braking ◽  
X Ray Binaries

Abstract We present a new method for constraining the mass transfer evolution of low-mass X-ray binaries (LMXBs)—a reverse population synthesis technique. This is done using the detailed 1D stellar evolution code MESA (Modules for Experiments in Stellar Astrophysics) to evolve a high-resolution grid of binary systems spanning a comprehensive range of initial donor masses and orbital periods. We use the recently developed convection and rotation-boosted (CARB) magnetic braking scheme. The CARB magnetic braking scheme is the only magnetic braking prescription capable of reproducing an entire sample of well-studied persistent LMXBs—those with mass ratios, periods, and mass transfer rates that have been observationally determined. Using the reverse population synthesis technique, where we follow any simulated system that successfully reproduces an observed LMXB backward, we have constrained possible progenitors for each observed well-studied persistent LMXB. We also determined that the minimum number of LMXB formations in the Milky Way is 1500 per Gyr if we exclude Cyg X-2. For Cyg X-2, the most likely formation rate is 9000 LMXB Gyr−1. The technique we describe can be applied to any observed LMXB with well-constrained mass ratio, period, and mass transfer rate. With the upcoming GAIA DR3 containing information on binary systems, this technique can be applied to the data release to search for progenitors of observed persistent LMXBs.

scholarly journals Formation of millisecond pulsars with helium white dwarfs, ultra-compact X-ray binaries, and gravitational wave sources

2021 ◽  
Vol 503 (3) ◽  
pp. 3540-3551 ◽  
Author(s):  
Hai-Liang Chen ◽  
Thomas M Tauris ◽  
Zhanwen Han ◽  
Xuefei Chen
Keyword(s):  
Gravitational Wave ◽  
White Dwarfs ◽  
Fine Tuning ◽  
Period Range ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Close Orbit ◽  
Low Mass ◽  
Magnetic Braking ◽  
X Ray Binaries

ABSTRACT Close-orbit low-mass X-ray binaries (LMXBs), radio binary millisecond pulsars (BMSPs) with extremely low-mass helium white dwarfs (ELM He WDs) and ultra-compact X-ray binaries (UCXBs) are all part of the same evolutionary sequence. It is therefore of uttermost importance to understand how these populations evolve from one specie to another. Moreover, UCXBs are important gravitational wave (GW) sources and can be detected by future space-borne GW observatories. However, the formation and evolutionary link between these three different populations of neutron star (NS) binaries are not fully understood. In particular, a peculiar fine-tuning problem has previously been demonstrated for the formation of these systems. In this investigation, we test a newly suggested magnetic braking prescription and model the formation and evolution of LMXBs. We compute a grid of binary evolution models and present the initial parameter space of the progenitor binaries which successfully evolve all the way to produce UCXBs. We find that the initial orbital period range of LMXBs, which evolve into detached NS + ELM He WD binaries and later UCXBs, becomes significantly wider compared to evolution with a standard magnetic braking prescription, and thus helps to relieve the fine-tuning problem. However, we also find that formation of wide-orbit BMSPs is prohibited for strong versions of this new magnetic braking prescription, which therefore calls for a revision of the prescription. Finally, we present examples of the properties of UCXBs as Galactic GW sources and discuss their detection by the LISA, TianQin, and Taiji observatories.

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.

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.

scholarly journals Drifts of the marginally stable burning frequency in the X-ray binaries 4U 1608–52 and Aql X–1

2021 ◽  
Vol 502 (2) ◽  
pp. 1856-1863
Author(s):  
G C Mancuso ◽  
D Altamirano ◽  
M Méndez ◽  
M Lyu ◽  
J A Combi
Keyword(s):  
Frequency Drift ◽  
Soft Or ◽  
Significance Level ◽  
X Ray ◽  
Intermediate States ◽  
Source State ◽  
Nuclear Burning ◽  
Low Mass ◽  
X Ray Binaries ◽  
Stable Burning

ABSTRACT We detect millihertz quasi-periodic oscillations (mHz QPOs) using the Rossi X-ray Time Explorer (RXTE) from the atoll neutron-star (NS) low-mass X-ray binaries 4U 1608–52 and Aql X–1. From the analysis of all RXTE observations of 4U 1608–52 and Aql X–1, we find mHz QPOs with a significance level >3σ in 49 and 47 observations, respectively. The QPO frequency is constrained between ∼4.2 and 13.4 mHz. These types of mHz QPOs have been interpreted as being the result of marginally stable nuclear burning of He on the NS surface. We also report the discovery of a downward frequency drift in three observations of 4U 1608–52, making it the third source that shows this behaviour. We only find strong evidence of frequency drift in one occasion in Aql X–1, probably because the observations were too short to measure a significant drift. Finally, the mHz QPOs are mainly detected when both sources are in the soft or intermediate states; the cases that show frequency drift only occur when the sources are in intermediate states. Our results are consistent with the phenomenology observed for the NS systems 4U 1636–53 and EXO 0748–676, suggesting that all four sources can reach the conditions for marginally stable burning of He on the NS surface. These conditions depend on the source state in the same manner in all four systems.

scholarly journals Search for intermittent X-ray pulsations from neutron stars in low-mass X-ray binaries

2021 ◽  
Vol 38 ◽  
Author(s):  
Yunus Emre Bahar ◽  
Manoneeta Chakraborty ◽  
Ersin Göğüş
Keyword(s):  
Neutron Stars ◽  
Orbital Period ◽  
Oscillation Frequency ◽  
Orbital Motion ◽  
X Rays ◽  
X Ray ◽  
Second Stage ◽  
Corrected Data ◽  
Low Mass ◽  
X Ray Binaries

Abstract We present the results of our extensive binary orbital motion corrected pulsation search for 13 low-mass X-ray binaries. These selected sources exhibit burst oscillations in X-rays with frequencies ranging from 45 to 1 122 Hz and have a binary orbital period varying from 2.1 to 18.9 h. We first determined episodes that contain weak pulsations around the burst oscillation frequency by searching all archival Rossi X-ray Timing Explorer data of these sources. Then, we applied Doppler corrections to these pulsation episodes to discard the smearing effect of the binary orbital motion and searched for recovered pulsations at the second stage. Here we report 75 pulsation episodes that contain weak but coherent pulsations around the burst oscillation frequency. Furthermore, we report eight new episodes that show relatively strong pulsations in the binary orbital motion corrected data.

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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