A very long X-ray burst with a precursor from XB 1715-321

Tawara, Yuzuru; Kii, T.; Hayakawa, S.; Kunieda, H.; Masai, K.; Nagase, F.; Inoue, H.; Koyama, K.; Makino, F.; Makishima, Kazuo; Matsuoka, M.; Murakami, T.; Oda, M.; Ogawara, Y.; Ohashi, T.; Shibazaki, N.; Tanaka, Yasuyuki; Miyamoto, S.; Tsunemi, H.; Yamashita, Kazuya; Kondò, I.

doi:10.1086/184184

Cited by 68 publications

(47 citation statements)

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“…K bb is proportional to the blackbody emitting area and the increase implies radius expansion, which is not expected to take place in the decay phase of the superburst light curve. Also, the count rate does not exhibit a dip, which is characteristic for PRE (Grindlay et al 1980;Tawara et al 1984;Lewin et al 1984). Furthermore, PRE is typically observed for bursts from 4U 1636-536 with peak blackbody fluxes in excess of 5 × 10 −8 erg s −1 cm −2 (in the PCA band; Galloway et al 2008), whereas the superburst does not reach that flux (Figure 4).…”

Section: Blackbody Emitting Area and The Power-law Cutoffmentioning

confidence: 89%

Characterizing the Evolving X-Ray Spectral Features During a Superburst From 4u 1636-536

Keek

Ballantyne

Kuulkers

et al. 2014

ApJ

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Recent studies have shown that runaway thermonuclear burning of material accreted onto neutron stars, i.e., Type I X-ray bursts, may affect the accretion disk. We investigate this by performing a detailed time-resolved spectral analysis of the superburst from 4U 1636-536 observed in 2001 with the Rossi X-Ray Timing Explorer. Superbursts are attributed to the thermonuclear burning of carbon, and are approximately 1000 times more energetic than the regular short Type I bursts. This allows us to study detailed spectra for over 11 ks, compared to, at most, 100 s for regular bursts. A feature is present in the superburst spectra around 6.4 keV that is well fit with an emission line and an absorption edge, suggestive of reflection of the superburst off the accretion disk. The line and edge parameters evolve over time: the edge energy decreases from 9.4 keV at the peak to 8.1 keV in the tail, and both features become weaker in the tail. This is only the second superburst for which this has been detected and shows that this behavior is present even without strong radius expansion. Furthermore, we find the persistent flux more than doubles during the superburst and returns to the pre-superburst value in the tail. The combination of reflection features and increased persistent emission indicates that the superburst had a strong impact on the inner accretion disk and it emphasizes that X-ray bursts provide a unique probe of accretion physics.

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Section: Blackbody Emitting Area and The Power-law Cutoffmentioning

confidence: 89%

Characterizing the Evolving X-Ray Spectral Features During a Superburst From 4u 1636-536

Keek

Ballantyne

Kuulkers

et al. 2014

ApJ

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“…If one ignores "superbursts" (e.g., Kuulkers et al 2002a), the burst duration and fluence are among the largest (cf., Tawara et al 1984;Lewin et al 1984;Van Paradijs et al 1990;Swank et al 1977;Kaptein et al 2000;Kuulkers et al 2002b). The amount of radiated energy, if isotropic, is between 1.0 and 2.2 × 10 41 erg.…”

Section: Discussionmentioning

confidence: 99%

Discovery of the neutron star nature of SLX 1737-282

Zand

Verbunt

Kuulkers

et al. 2002

A&A

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Abstract. SLX 1737−282 is a persistent moderately bright X-ray source 1.• 2 from the Galactic center. X-ray observations with the Wide Field Cameras on BeppoSAX have for the first time revealed the true nature of SLX 1737−282: a 15 min long thermonuclear flash was detected exposing the source as a neutron star in a binary system. The flash was Eddington-limited constraining the distance to between 5 and 8 kpc. We analyze BeppoSAX, ROSAT, and RXTE data on SLX 1737−282. The persistent 0.5-200 keV luminosity is close to or less than 1% of the Eddington limit which implies a rarely-seen circumstance for thermonuclear flash activity.

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“…A similar, but much weaker, precursor can be seen in the helium Ñash burst just prior to the onset of the superburst. This behavior is characteristic of very powerful photospheric radius expansion bursts (see Ho †man et al 1978 ;Tawara et al 1984 ;Lewin, Vacca, & Basinska 1984 ;van Paradijs et al 1990). Note also the hardening of the spectrum following the precursor.…”

Section: General Descriptionmentioning

confidence: 91%

A Remarkable 3 Hour Thermonuclear Burst from 4U 1820−30

Strohmayer

Brown

2002

ApJ

241

402

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We present a detailed observational and theoretical study of a D3 hr long X-ray burst (the "" superburst ÏÏ) observed by the Rossi X-Ray T iming Explorer (RXT E) from the low-mass X-ray binary 4U 1820[30. This is the longest X-ray burst ever observed from this source and perhaps one of the longest ever observed in great detail from any source. We show that the superburst is thermonuclear in origin. Its peak luminosity of D3.4 ] 1038 ergs s~1 is consistent with the helium Eddington limit for a neutron star at D7 kpc as well as the peak luminosity of other, shorter, thermonuclear bursts from the same source. The superburst begins in the decaying tail of a more typical (B20 s duration) thermonuclear burst. These shorter, more frequent bursts are well-known helium Ñashes from this source. The level of the accretion-driven Ñux as well as the observed energy release of upward of 1.5 ] 1042 ergs indicate that helium could not be the energy source for the superburst. We outline the physics relevant to carbon production and burning on helium-accreting neutron stars and present calculations of the thermal evolution and stability of a carbon layer and show that this process is the most likely explanation for the superburst. Ignition at the temperatures in the deep carbon "" ocean ÏÏ requires more than 30 times the mass of carbon inferred from the observed burst energetics unless the He Ñash is able to trigger a deÑagration from a much smaller mass of carbon. We show, however, that for large columns of accreted carbon fuel, a substantial fraction of the energy released in the carbon-burning layer is radiated away as neutrinos, and the heat that is conducted from the burning layer in large part Ñows inward, only to be released on timescales longer than the observed burst. Thus, the energy released during the event possibly exceeds that observed in X-rays by more than a factor of 10, making the scenario of burning a large mass of carbon at great depths consistent with the observed Ñuence without invoking any additional trigger. A strong constraint on this scenario is the recurrence time : to accrete an ignition column of 1013 g cm~2 takes g s~1) yr. Spectral analysis during the superburst reveals the D13/(M 0 /3 ] 1017 presence of a broad emission line between 5.8 and 6.4 keV and an edge at 8È9 keV, likely due to reÑec-tion of the burst Ñux from the inner accretion disk in 4U 1820[30. We believe that this is the Ðrst time such a signature has been unambiguously detected in the spectrum of an X-ray burst.

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A very long X-ray burst with a precursor from XB 1715-321

Cited by 68 publications

References 0 publications

Characterizing the Evolving X-Ray Spectral Features During a Superburst From 4u 1636-536

Characterizing the Evolving X-Ray Spectral Features During a Superburst From 4u 1636-536

Discovery of the neutron star nature of SLX 1737-282

A Remarkable 3 Hour Thermonuclear Burst from 4U 1820−30

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