Fluctuation at the neutron star centre gives rise to a small deconfined quark core very close to the star centre. The density discontinuity at the quark–hadron boundary initiates a shock wave, which propagates outwards of the star. The shock has enough energy to combust nuclear matter to 2-flavour quark matter in the star. The 2-flavour quark matter is not stable and settles to a stable 3-flavour matter in the weakly interacting time-scale. In this paper, we study the conversion of 2-flavour matter to 3-flavour matter. We set-up a differential equation to convert the excess of down quarks to strange quarks involving weak reaction and diffusion of quarks. Calculating the reaction rate and diffusion, we solve the differential equation to find the velocity of the conversion front. As the conversion front moves out, the density profile changes, bringing about a change in the star’s quadrupole moment and thereby emitting gravitational waves (GWs). As the conversion process occurs, the temperature of the star rises, but the neutrino carries away the heat in some tens of ms. The GW amplitude of a colder star is well within the present detector capability, but the frequency is slightly on the higher side. Relatively hotter stars are on the boundary of present detectors and easily detectable with future detectors, and their frequency is also within the present detectability range. In comparison, phase transition from Galactic pulsars is easily detectable with present detectors.

中文翻译：

---

燃烧中子星到夸克星相变的引力波特征

中子星中心的波动会产生一个非常靠近星中心的小夸克核心。夸克-强子边界处的密度不连续性引发了冲击波，该冲击波向外传播。激波有足够的能量在恒星中将核物质燃烧成二味夸克物质。2 味夸克物质是不稳定的，在弱相互作用的时间尺度内稳定为稳定的 3 味物质。在本文中，我们研究了 2 味物质到 3 味物质的转化。我们建立了一个微分方程，将多余的下夸克转化为奇夸克，涉及夸克的弱反应和扩散。计算反应速率和扩散，我们求解微分方程以找到转换前沿的速度。随着转换前沿向外移动，密度分布发生变化，导致恒星的四极矩发生变化，从而发射引力波（GW）。随着转换过程的发生，恒星的温度会升高，但中微子会在几十毫秒内带走热量。较冷恒星的 GW 幅度在目前的探测器能力范围内，但频率略偏高。相对较热的恒星处于现有探测器的边界，未来的探测器很容易探测到，它们的频率也在目前的可探测范围内。相比之下，银河脉冲星的相变很容易用现有的探测器探测到。但是中微子会在几十毫秒内带走热量。较冷恒星的 GW 幅度在目前的探测器能力范围内，但频率略偏高。相对较热的恒星处于现有探测器的边界，未来的探测器很容易探测到，它们的频率也在目前的可探测范围内。相比之下，银河脉冲星的相变很容易用现有的探测器探测到。但是中微子会在几十毫秒内带走热量。较冷恒星的 GW 幅度在目前的探测器能力范围内，但频率略偏高。相对较热的恒星处于现有探测器的边界，未来的探测器很容易探测到，它们的频率也在目前的可探测范围内。相比之下，银河脉冲星的相变很容易用现有的探测器探测到。