Superbursts and long bursts as surface phenomenon of compact objects

Abstract

X-ray bursts from compact stars is believed to be due to type I thermonuclear processes which are short lived, typically ~ 10 to 100 s. There are some low mass X-ray binaries (LMXB) like 4U 1820-30, 4U 1636-53, KS 1731-260 and Serpens X-1, known as Super Bursters (SB) which emit X-rays close to the Eddington luminosity limit for long periods of several hours. Recently there are reports of some long bursters (LB), which have bursts lasting 6-25 minutes, whereas the 4U 1735-44 has a burst period of 86 minutes. We suggest that these bursts from SB and LB may be due to breaking and re-formation of diquark pairs, on the surface of realistic strange quark stars. We use the beta equilibrated u, d and s quark model of Dey et al. (1998) and Li et al. (1999a and 1999b) and allow for spin dependent hyperfine interaction between quarks. The interaction produces pairing of specific colour-spin diquarks, leading to further lowering of energy by several MeV-s for each pair, on the average. Diquarks are expected to break up due to the explosion and shock of the TN process. The subsequent production of copious diquark pairing may produce sufficient energy to produce the very long bursts seen in SB or LB. The estimated total energy liberated, 10^{42} ergs, can be explained in our model with the calculated pair density ~ 0.275/fm^3 and a surface thickness of only half a micron, if the entire surface is involved. The depth of the surface involved in the process may be only few microns if the process is restricted to small part of the surface near the equator as suggested by Bildsten.

4 pages, 1 figure. Accepted for publication in MNRAS

References in corpus (13)

• The Condensed Matter Physics of QCD
• Is SAX J1808.4-3658 a Strange Star ?
• A Remarkable Three Hour Thermonuclear Burst From 4U 1820-30
• Carbon Flashes in the Heavy Element Ocean on Accreting Neutron Stars
• Conversion of neutron stars to strange stars as the central engine of gamma-ray bursts
• A Chandra observation of the long-duration X-ray transient KS 1731-260 in quiescence: too cold a neutron star?
• On the nature of the compact star in 4U 1728-34
• A superburst from 4U 1254-690
• Recurrent very-long type-I X-ray bursts in the low-mass X-ray binary 4U 1636-53
• Theory and Observations of Type I X-Ray Bursts from Neutron Stars
• A four-hours long burst from Serpens X-1
• Density dependent strong coupling constant of QCD derived from compact star data
• Droplet Formation in Quark-Gluon Plasma at Low Temperatures and High Densities

Cited by in corpus (16)

• On the Lack of Thermal Emission from the Quiescent Black Hole XTE J1118+480: Evidence for the Event Horizon
• Constraining values of bag constant for strange star candidates
• Superbursts from Strange Stars
• Origin and interpretation of kilohertz QPOs from strange stars in X-ray binary system: theoretical hydrodynamical description
• Compact strange stars with a medium dependence in gluons at finite temperature
• A model finding a new Richardson potential with different scales for confinement and asymptotic freedom, by fitting the properties of ${\D}^{++}$ and ${\Om}^{-}$
• Have we observed the skin vibration of realistic strange stars (ReSS) ?
• Possible evidence of surface vibration of strange stars from stellar observations
• Evidence for strange stars from joint observation of harmonic absorption bands and of redshift
• Strange Pulsar Hypothesis
• Incompressibility of strange matter
• Newtonian and general relativistic contribution of gravity to surface tension of strange stars
• Chromo-thermal oscillations and collapse of strange stars to black holes : Astrophysical Implications
• Decoupling of pion coupling f_π from quarks at high density in three models, and its possible observational consequences
• Addendum to ``Decoupling of pion coupling $f_{\pi }$ from quarks at high density in three models, and its possible observational consequences"
• Bound for entropy and viscosity ratio for strange quark matter