Millisecond X-ray bursts from Circinus X-1

Toor, A.

doi:10.1086/182477

Cited by 33 publications

(19 citation statements)

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“…The large ratio suggests that Cir X-1 L X /L opt is a low-mass X-ray binary (LMXB). For a long time it was suspected that the compact object in Cir X-1 was a black hole, for the rapid variability was similar to that of Cyg X-1 (Toor 1977). However, the presence of a neutron star was demonstrated by the detection of type I X-ray bursts (Tennant, Fabian, & Shafer 1986a, 1986b.…”

Section: Introductionmentioning

confidence: 99%

A Hard Tail in the X‐Ray Broadband Spectrum of Circinus X‐1 at the Periastron: A Peculiar Z Source

Iaria

Burderi

Salvo

et al. 2001

ApJ

100

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We report on the spectral analysis of the peculiar source Cir X-1 observed by the BeppoSAX satellite when the X-ray source was near the periastron. A Ñare lasting D6 ] 103 s is present at the beginning of the observation. The luminosity during the persistent emission is 1 ] 1038 ergs s~1, while during the Ñare it is 2 ] 1038 ergs s~1. We produced broadband (0.1È100 keV) energy spectra during the Ñare and the persistent emission. At low energies the continuum is well Ðtted by a model consisting of Comptonization of soft photons, with a temperature of D0.4 keV, by electrons at a temperature of D1 keV. After the Ñare, a power-law component with photon index D3 is dominant at energies higher than 10 keV. This component contributes D4% of the total luminosity. During the Ñare its addition is not statistically signiÐcant. An absorption edge at D8.4 keV, with optical depth D1, corresponding to the K edge of Fe XXIIIÈFe XXV, and an iron emission line at 6.7 keV are also present. The iron-line energy is in agreement with the ionization level inferred from the absorption edge. The hydrogen column deduced from the absorption edge is D1024 cm~2, 2 orders of magnitude larger than the low-energy absorption measured in this source. We calculated the radius of the region originating the Comptonized seed photons, km. We propose a scenario where (the Wien radius) is the inner disk radius, a R W D 150 R W highly ionized torus surrounds the accretion disk, and a magnetosphere is present up to The R W . absorption edge and the emission line could originate in the photoionized torus, while the Comptonized component originates in an inner region of the disk.

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Section: Introductionmentioning

confidence: 99%

A Hard Tail in the X‐Ray Broadband Spectrum of Circinus X‐1 at the Periastron: A Peculiar Z Source

Iaria

Burderi

Salvo

et al. 2001

ApJ

100

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“…It shows QPO with frequencies between 6 and 20 Hz and no second harmonics (both Ζ source characteristics) in combination with messy branches in the CD/HID and fast changes in the shape of the broad-band noise (BHC characteristics). The reason, then, that CirX-1 sometimes resembles a black hole in its rapid variability characteristics, as was noted by Toor (1977) and Samimi et al (1979) neutron star, is that it is the only neutron star that we know that has a magnetic field as low as in atoll sources that sometimes accretes at nearor super-Eddington rates. Cir X-l is therefore a key object as it can help to distinguish between phenomena that are characteristic for accretion onto any compact object that has no appreciable magnetic field, and phenomena that are truly characteristic for accretion onto a black hole.…”

Section: Similarities Between Black-hole Candidates and Low Magneticfmentioning

confidence: 77%

Low-Mass X-ray Binaries—Recent Developments

Klis¹

1996

Symp. - Int. Astron. Union

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“…The reason, then, that Cir X-l sometimes resembles a black hole in its rapid variability characteristics, (e.g. Toor 1977, Samimi 1979, while its X-ray bursts (Tennant et al 1986a, b) show it to be a neutron Fig. 2.…”

Section: Black-hole-candidate Powermentioning

confidence: 99%

Quasi-periodic Oscillations and Noise in Accreting Black Holes and Low-magnetic Field Neutron Stars

Klis

1995

International Astronomical Union Colloquium

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The X-ray spectrum and the rapid X-ray variability of accreting compact objects have a common origin, and their properties can therefore be expected to be coupled. Indeed, it turns out that the X-ray spectrum and the power spectrum show correlated variations, which occur as a function of variations in the mass fluxx Ṁ.Stellar mass black holes and neutron stars have similar mass and size, and therefore their accretion phenomena may be expected to show similarities. Indeed, similarities exist that indicate that a unified description may be possible. If a particular phenomenon is seen in both neutron star and black-hole candidate systems this shows immediately that it cannot be due to any property that is unique to either neutron stars or black holes, such as the presence or absence of a surface, or of a strong non-aligned magnetic field. The quest for characteristics that are unique to black holes continues - I shall mention a few candidates below.

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Millisecond X-ray bursts from Circinus X-1

Cited by 33 publications

References 0 publications

A Hard Tail in the X‐Ray Broadband Spectrum of Circinus X‐1 at the Periastron: A Peculiar Z Source

A Hard Tail in the X‐Ray Broadband Spectrum of Circinus X‐1 at the Periastron: A Peculiar Z Source

Low-Mass X-ray Binaries—Recent Developments

Quasi-periodic Oscillations and Noise in Accreting Black Holes and Low-magnetic Field Neutron Stars

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