Speaker
Description
In accreting neutron stars, rapidly brightening phenomena have often been observed, so-called Type-I bursts. Most of them are observed in a hard state, that is, a relatively dark phase. In the hard state, most observations show an inverse relation between burst recurrence time and accretion rate, which is in line with conventional burst models.
Recently, many bursters have been observed when they transit accretion regime from soft state to hard state, the former of which shows brighter persistently. In this case, burst observations tend to show a shorter burst recurrence time than that expected from the inverse relation, implying a new physical mechanism beyond conventional burst models.
As one of the solutions to resolve such a recurrence-time anomaly, we propose the contribution of residual heating, the excess heat inside the accreting neutron star crust in the past soft state. Although most previous burst models follow the thermal evolution of only the bursting atmosphere, to consider the effect of residual heating, one should follow whole neutron-star cooling in Type-I burst simulations. We perform burst simulations in accreting neutron stars that simultaneously cool due to thermal emission, with different cooling timescales and accretion rates in the soft state. We also argue whether the recurrence time anomaly could be solved in some latest observations.
| Category | Theory |
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