Linking Soft Excess in Ultraluminous X-Ray Sources with Optically Thick Wind Driven by Supercritical Accretion

IUE has been used to study 11 high luminosity X-ray binaries, of which 3 are in the Magellanic Clouds. In the supergiant systems, X-ray ionisation bubbles have been found in most cases, leading to a greater understanding of the winds and accretion processes. Further studies of precessing objects such as LMC X-4 with IUE and ST are clearly of considerable interest, relating to X-ray heating and blanketing. Detailed studies of the Cyg X-l ionisation bubble may resolve the long standing puzzle of its orbit inclination and masses. UV continua have furnished valuable information on extinction, temperatures and luminosities, and the presence of non-stellar (i.e. disk) luminosity. Here too, more detailed studies are clearly indicated for the future. A unique object of interest is the LMC transient 0538-66 whose UV spectrum has quasarlike lines and luminosity which varies oppositely to the visible. This may be a case of supercritical accretion generating an optically thick shell (“disk”) about the pulsar.

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Constraining Soft and Hard X-Ray Irradiation in Ultraluminous X-Ray Sources

The Astrophysical Journal ◽

10.3847/1538-4357/ac3569 ◽

2021 ◽

Vol 922 (2) ◽

pp. 91

Author(s):

Yanli Qiu ◽

Hua Feng

Keyword(s):

Optical Emission ◽

Current Data ◽

Compact Objects ◽

X Rays ◽

Optical Counterpart ◽

X Ray ◽

Outer Disk ◽

Stringent Constraint ◽

Supercritical Accretion ◽

Key Questions

Abstract Most ultraluminous X-ray sources (ULXs) are argued to be powered by supercritical accretion onto compact objects. One of the key questions regarding these objects is whether or not the hard X-rays are geometrically beamed toward the symmetric axis. We propose testing the scenario using disk irradiation to see how much the outer accretion disk sees the central hard X-rays. We collect a sample of 11 bright ULXs with an identification of a unique optical counterpart, and model their optical fluxes considering two irradiating sources: soft X-rays from the photosphere of the optically thick wind driven by supercritical accretion, and if needed in addition, hard X-rays from the Comptonization component. Our results indicate that the soft X-ray irradiation can account for the optical emission in the majority of ULXs, and the fraction of hard X-rays reprocessed on the outer disk is constrained to be no more than ∼10−2 in general. Such an upper limit is well consistent with the irradiation fraction expected in the case of no beaming. Therefore, no stringent constraint on the beaming effect can be placed according to the current data quality.

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X-ray binaries with neutron stars at different accretion stages

Proceedings of the International Astronomical Union ◽

10.1017/s174392131900125x ◽

2018 ◽

Vol 14 (S346) ◽

pp. 219-227

Author(s):

Konstantin A. Postnov ◽

Alexander G. Kuranov ◽

Lev R. Yungelson

Keyword(s):

Magnetic Fields ◽

Neutron Stars ◽

Orbital Period ◽

Population Synthesis ◽

Circular Orbits ◽

X Ray ◽

Accretion Rates ◽

Supercritical Accretion ◽

Binary Evolution ◽

X Ray Binaries

Abstract. Different accretion regimes onto magnetized NSs in HMXBs are considered: wind-fed supersonic (Bondi) regime at high accretion rates <math/> g s-1, subsonic settling regime at lower <math/> and supercritical disc accretion during Roche lobe overflow. In wind-fed stage, NSs in HMXBs reach equilibrium spin periods P* proportional to binary orbital period Pb. At supercritical accretion stage, the system may appear as a pulsating ULX. Population synthesis of Galactic HMXBs using standard assumptions on the binary evolution and NS formation is presented. Comparison of the model P* – Pb (the Corbet diagram), P* – Lx and Pb – Lx distributions with those for the observed HMXBs (including Be X-ray binaries) and pulsating ULXs suggests the importance of the reduction of P* in non-circular orbits, explaining the location of Be X-ray binaries in the model Corbet diagram, and the universal parameters of pulsating ULXs depending only on the NS magnetic fields.

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Face-on SS 433 Stars as a Possible New Type of Extragalactic X-Ray Sources

Symposium - International Astronomical Union ◽

10.1017/s0074180900221165 ◽

2001 ◽

Vol 205 ◽

pp. 268-269 ◽

Cited By ~ 13

Author(s):

S. Fabrika ◽

A. Mescheryakov

Keyword(s):

X Rays ◽

Relativistic Jets ◽

Expected Frequency ◽

X Ray ◽

Ss 433 ◽

Sky Survey ◽

Supercritical Accretion ◽

The Face ◽

New Type ◽

Positive Correlations

The object SS433 is a well-known source of relativistic jets, which are formed in supercritical accretion disk. It is very probable that the disk has polar channels and their radiation is collimated (the photo-cones). A face-on SS433 object can appear as ultra-bright and highly variable X-ray source, Lx ˜ 1040 − 1042 erg/s. We discuss the properties of these hypothetical objects and their frequency expected in galaxies. We describe a search for such objects using the ROSAT All Sky Survey and RC3 catalog of galaxies. Among the total 418 positive correlations we find that 142 sources in S and Irr galaxies are unknown as AGNs. Nuclear sources among them still contain many AGNs. Non-nuclear (offset) sources are rather hard, their X-ray luminosities are 1039 − 1041 erg/s. Their observed frequency is about 4–5% per galaxy, that is in agreement with expected frequency of the face-on SS 433 stars. The only way to recognize such stars is their expected violent variability in X rays.

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X-ray variability of SS 433: effects of the supercritical accretion disc

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stu2134 ◽

2014 ◽

Vol 446 (1) ◽

pp. 893-910 ◽

Cited By ~ 5

Author(s):

Kirill Atapin ◽

Sergei Fabrika ◽

Aleksei Medvedev ◽

Alexander Vinokurov

Keyword(s):

Accretion Disc ◽

X Ray ◽

Ss 433 ◽

Supercritical Accretion

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X-ray radiation of the jets and the supercritical accretion disk in SS 433

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310016169 ◽

2010 ◽

Vol 6 (S275) ◽

pp. 280-284 ◽

Cited By ~ 1

Author(s):

Sergei Fabrika ◽

Alexei Medvedev

Keyword(s):

Accretion Disk ◽

Spectral Component ◽

Emission Lines ◽

X Rays ◽

X Ray ◽

Ss 433 ◽

Disk Wind ◽

Bolometric Luminosity ◽

Supercritical Accretion ◽

The Continuum

AbstractThe observed X-ray luminosity of SS 433 is ~1036 erg/s, it is known that all the radiation is formed in the famous SS 433 jets. The bolometric luminosity of SS 433 is ~1040 erg/s, and originally the luminosity must be realized in X-rays. The original radiation is probably thermalized in the supercritical accretion disk wind, however the missing more than four orders of magnitude is surprising. We have analysed the XMM-Newton spectra of SS 433 using a model of adiabatically and radiatively cooling X-ray jets. The multi-temperature thermal jet model reproduces very well the strongest observed emission lines, but it can not reproduce the continuum radiation and some spectral features. We have found a notable contribution of ionized reflection to the spectrum in the energy range from ~3 to 12 keV. The reflected spectrum is an evidence of the supercritical disk funnel, where the illuminating radiation comes from deeper funnel regions, to be further reflected in the outer visible funnel walls (r ≥ 2 ⋅ 1011 cm). The illuminating spectrum is similar to that observed in ULXs, its luminosity has to be no less than ~1039 erg/s. A soft excess has been detected, that does not depend on the thermal jet model details. It may be represented as a BB with a temperature of Tbb ≈ 0.1 keV and luminosity of Lbb~3 ⋅ 1037 erg/s. The soft spectral component has about the same parameters as those found in ULXs.

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The supercritical accretion disk in SS 433 and ultraluminous X-ray sources

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307005017 ◽

2006 ◽

Vol 2 (S238) ◽

pp. 225-228

Author(s):

S. N. Fabrika ◽

P. K. Abolmasov ◽

S. Karpov

Keyword(s):

Accretion Disk ◽

Accretion Disks ◽

X Rays ◽

X Ray ◽

Ss 433 ◽

Disk Wind ◽

Flux Variability ◽

Typical Time ◽

Supercritical Accretion ◽

External Galaxies

AbstractSS 433 is the only known persistent supercritical accretor, it may be very important for understanding ultraluminous X-ray sources (ULXs) located in external galaxies. We describe main properties of the SS 433 supercritical accretion disk and jets. Basing on observational data of SS 433 and published 2D simulations of supercritical accretion disks we estimate parameters of the funnel in the disk/wind of SS 433. We argue that the UV radiation of the SS 433 disk (∼ 50000 K, ∼ 1040erg/s) is roughly isotropic, but X-ray radiation (∼ 107K, ∼ 1040erg/s) of the funnel is mildly anisotropic. A face-on SS 433 object has to be ultraluminous in X-rays (1040–41erg/s). Typical time-scales of the funnel flux variability are estimated. Shallow and very broad (0.1-0.3c) and blue-shifted absorption lines are expected in the funnel X-ray spectrum.

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