A catalogue of low-mass X-ray binaries in the Galaxy, LMC, and SMC (Fourth edition)

In this study we compare the global populations of stellar X-ray sources in the LMC, SMC, and the Galaxy. After removing foreground stars and background AGN from the samples, the relative numbers of the various types of X-ray point sources within the LMC and SMC are similar, but differ markedly from those in the Galaxy. The Magellanic Clouds are rich in high-mass X-ray binaries (HMXB), especially those containing rapidly rotating Be stars. However, the LMC and SMC both lack the large number of low-mass X-ray binaries (LMXB) found in the Milky Way, which are known to represent a very old stellar population based on their kinematics, chemical composition, and spatial distribution.

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A strange star scenario for the formation of isolated millisecond pulsars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935132 ◽

2020 ◽

Vol 633 ◽

pp. A45 ◽

Cited By ~ 1

Author(s):

Long Jiang ◽

Na Wang ◽

Wen-Cong Chen ◽

Xiang-Dong Li ◽

Wei-Min Liu ◽

...

Keyword(s):

Neutron Star ◽

Galactic Plane ◽

Critical Mass ◽

Strange Star ◽

Millisecond Pulsars ◽

X Ray ◽

Mass Distributions ◽

The Galaxy ◽

Low Mass ◽

X Ray Binaries

According to the recycling model, neutron stars in low-mass X-ray binaries were spun up to millisecond pulsars (MSPs), which indicates that all MSPs in the Galactic plane ought to be harbored in binaries. However, about 20% Galactic field MSPs are found to be solitary. To interpret this problem, we assume that the accreting neutron star in binaries may collapse and become a strange star when it reaches some critical mass limit. Mass loss and a weak kick induced by asymmetric collapse during the phase transition (PT) from neutron star to strange star can result in isolated MSPs. In this work, we use a population-synthesis code to examine the PT model. The simulated results show that a kick velocity of ∼60 km s−1 can produce ∼6 × 103 isolated MSPs and birth rate of ∼6.6 × 10−7 yr−1 in the Galaxy, which is approximately in agreement with predictions from observations. For the purpose of comparisons with future observation, we also give the mass distributions of radio and X-ray binary MSPs, along with the delay time distribution.

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GAMA/XXL: X-ray point sources in low-luminosity galaxies in the GAMA G02/XXL-N field

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab242 ◽

2021 ◽

Vol 502 (2) ◽

pp. 3101-3112

Author(s):

E Nwaokoro ◽

S Phillipps ◽

A J Young ◽

I Baldry ◽

A Bongiorno ◽

...

Keyword(s):

Positional Information ◽

Point Sources ◽

High Mass ◽

X Ray ◽

Star Forming ◽

Flux Limit ◽

The Galaxy ◽

Low Mass ◽

Mass Assembly ◽

X Ray Binaries

ABSTRACT Relatively few X-ray sources are known that have low-mass galaxies as hosts. This is an important restriction on studies of active galactic nuclei (AGNs), hence black holes, and of X-ray binaries (XRBs) in low-mass galaxies; addressing it requires very large samples of both galaxies and X-ray sources. Here, we have matched the X-ray point sources found in the XXL-N field of the XXL survey (with an X-ray flux limit of ∼6 × 10−15 erg s−1 cm−2 in the [0.5–2] keV band) to galaxies with redshifts from the Galaxy And Mass Assembly (GAMA) G02 survey field (down to a magnitude limit r = 19.8) in order to search for AGNs and XRBs in GAMA galaxies, particularly those of low optical luminosity or stellar mass (fainter than Mr = −19 or $M_* \lesssim 10^{9.5}\, \mathrm{M}_{\odot }$). Out of a total of 1200 low-mass galaxies in the overlap region, we find a total of 28 potential X-ray source hosts, though this includes possible background contaminants. From a combination of photometry (optical and infrared colours), positional information, and optical spectra, we deduce that most of the ≃20 X-ray sources genuinely in low-mass galaxies are high-mass X-ray binaries in star-forming galaxies. None of the matched sources in a low-mass galaxy has a BPT classification as an AGN, and even ignoring this requirement, none passes both criteria of close match between the X-ray source position and optical galaxy centre (separation ≤3 arcsec) and high [O iii] line luminosity (above 1040.3 erg s−1).

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Globular Cluster X-Ray Sources

Highlights of Astronomy ◽

10.1017/s1539299600002458 ◽

1977 ◽

Vol 4 (1) ◽

pp. 111-122 ◽

Cited By ~ 4

Author(s):

Jonathan E. Grindlay

Keyword(s):

Black Hole ◽

Globular Clusters ◽

High Energy ◽

High Energy Astrophysics ◽

X Ray ◽

High Incidence ◽

The Galaxy ◽

Low Mass ◽

Future Work ◽

X Ray Binaries

The discoveries of both steady and bursting X-ray sources in globular clusters have made them as interesting for high energy astrophysics and X-ray astronomy as they were for unlocking galactic structure in Shapley’ s day. Globular clusters are massive (˜ 105M⊙) spherical clusters of primarily low mass (⋞0.8 M⊙) evolved stars and may be the oldest systems in the Galaxy. Thus when several globular clusters were tentatively identified as containing X-ray sources (Giacconiet al. 1974), it was apparent that either dynamical or evolutionary processes must be occurring among the ancient stars in globular clusters to produce the relatively short-lived X-ray sources. The existence of these X-ray sources has prompted considerable discussion as to their origin, since they exist with ˜100 times the probability per unit mass in globular clusters as in the Galaxy as a whole (Katz 1975; Clark 1975). They may be yet another example of X-ray binaries (e. g., Clark 1975; Fabianet al. 1975) or be due to accretion onto a single collapsed object (black hole) at the center of the cluster (Bahcall and Ostrlker 1975; Silk and Arons 1975). At present both of these classes of models are possible and generally consistent with the data, though each has its particular difficulties. We shall review the observational data and then the models in an effort to point out the present balance of evidence for the binaryvs.black hole models as well as the most promising directions for future work. Given the possibly high incidence of X-ray bursters in globular clusters, our discussion will refer to both observations and recent models for bursters. While this review will primarily address the X-ray sources in globular clusters, it is obvious that their eventual understanding will contribute much to studies of globular clusters in general and will prompt future studies in particular areas.

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Millisecond Pulsar Formation and Evolution

Symposium - International Astronomical Union ◽

10.1017/s0074180900161017 ◽

1987 ◽

Vol 125 ◽

pp. 393-406 ◽

Cited By ~ 1

Author(s):

E.P.J. van den Heuvel

Keyword(s):

Neutron Stars ◽

Millisecond Pulsar ◽

Radio Pulsars ◽

X Ray ◽

Binary Pulsars ◽

The Galaxy ◽

History Of ◽

Low Mass ◽

Formation And Evolution ◽

X Ray Binaries

The evolutionary history of binary radio pulsars, including the two millisecond binary pulsars, is reviewed. There are two groups of binary pulsars, the PSR 1913+16-group, which descended from massive X-ray binaries, and the PSR 1953+29-group, which descended from fairly wide low-mass X-ray binaries. The neutron stars in the second group probably formed by the accretion-induced collapse of a massive white dwarf. The companion stars in both groups of systems are expected to be dead stars, i.e. white dwarfs or neutron stars.The large total number of millisecond binary pulsars in the galaxy (∼ 104), indicates that magnetic fields of neutron stars do not decay below a value of order 109 G. Possible explanations for this phenomenon are discussed.Coalescence with a close degenerate companion provides a viable model for the formation of the single millisecond pulsar.

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Populating the Galaxy with low-mass X-ray binaries

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2006.10400.x ◽

2006 ◽

Vol 369 (3) ◽

pp. 1152-1166 ◽

Cited By ~ 66

Author(s):

P. D. Kiel ◽

J. R. Hurley

Keyword(s):

X Ray ◽

The Galaxy ◽

Low Mass ◽

X Ray Binaries

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Radiatively inefficient accretion in short-period black hole low mass X-ray binaries

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314001136 ◽

2013 ◽

Vol 9 (S303) ◽

pp. 456-457

Author(s):

Riley M. T. Connors

Keyword(s):

Black Hole ◽

Statistical Evidence ◽

X Ray ◽

Central Object ◽

Short Period ◽

The Galaxy ◽

Transient Sources ◽

Low Mass ◽

X Ray Binaries ◽

Over Time

AbstractThere is statistical evidence for a dearth of short-period (Porb < 4h) black hole (BH) low mass X-ray binaries (LMXBs) in the Galaxy. At short periods accretion onto the central object (be it a BH) may become inefficient because the cooling timescale of the gas is greater than the accretion timescale (this is the well known ADAF model). The nature of the switch is important in terms of the outburst timescales of transient sources. The switch may be sharp or occur smoothly over time. I show that the dearth can be explained if the switch to inefficiency occurs sharply at some fraction of the Eddington luminosity of the BH (fLEdd).

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Iron K-Line Emission from X-Ray Binaries

International Astronomical Union Colloquium ◽

10.1017/s0252921100107389 ◽

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.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3410 ◽

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.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab159 ◽

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.

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