使用CoCoA对亚太阳质量中子星与超千新星的长持续时间引力波搜寻
Long-duration GW Searches for Sub-solar NSs and Superkilonovae using CoCoA
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中文总结 AI 辅助
本研究针对亚太阳质量中子星与超千新星的长持续时间引力波信号，采用更稳健的互相关算法CoCoA开展搜寻，为探测超千新星场景及中子星与黑洞的质量间隙下限提供新途径。
中文摘要 AI 辅助
2025年8月18日，LIGO-Virgo-KAGRA合作组报告了一个亚阈值引力波（GW）候选体S250818k，其与潜在包含亚太阳质量致密天体的双中子星（NS）并合事件相符。后续电磁（EM）观测在该引力波信号的宽定位区域内发现了IIb型超新星SN 2025ulz。尽管由于S250818k的统计显著性较低，这一亚太阳质量引力波候选体与IIb型超新星的潜在关联尚未得到证实，但它重新激发了人们对“超千新星”场景的兴趣——在该场景中，亚太阳质量中子星通过吸积盘碎裂或坍缩恒星的核心裂变等过程形成。根据该场景，亚太阳质量双中子星的旋进与并合之后，会发生双中子星并合产物与中心黑洞（BH）的并合，产生类啁啾引力波信号。对于质量处于0.1-1倍太阳质量范围的亚太阳质量中子星，以及质量处于约3-5倍太阳质量（所谓的质量间隙下限范围）的黑洞，这些信号可在地面引力波探测器的20-1024赫兹频段内持续10^2-10^3秒，为探测超千新星场景以及中子星与恒星质量黑洞之间的质量间隙下限提供了潜在机会。然而，潜在天体物理过程的复杂性可能会产生偏离标准模板的波形，限制了匹配滤波在实际引力波搜寻中的应用。因此，我们使用更稳健但灵敏度较低的互相关算法（CoCoA）探究此类信号的可探测性。我们讨论了实施CoCoA超千新星搜寻的通用策略，包括两种方式：一是对匹配滤波搜寻中识别出的类啁啾候选体进行定向后续观测，二是对剥离包层的核心坍缩超新星进行电磁触发搜寻。
英文摘要
On 2025 August 18, the LIGO-Virgo-KAGRA collaboration reported a sub-threshold gravitational-wave (GW) candidate, S250818k, consistent with a binary neutron star (NS) merger potentially involving a sub-solar-mass compact object. Follow-up electromagnetic (EM) observations identified a Type IIb supernova, SN 2025ulz within the broad localization area of the GW signal. This potential link between a sub-solar GW event candidate and a Type IIb SN, while not confirmed given the low statistical significance of S250818k, has nonetheless sparked renewed interest in the "superkilonova" scenario, where sub-solar-mass NSs form through processes like the fragmentation of an accretion disk or core fission in a collapsing star. In this picture, the in-spiral and merger of a sub-solar NS-NS binary is followed by the merger of the NS-NS remnant with the central black hole (BH), producing chirp-like GW signals. For sub-solar NSs with masses in the (0.1-1)M_sun range and BH masses in the so-called lower mass gap range of ~(3-5) M_sun, these signals can persist in the 20 - 1024 Hz frequency band of ground-based GW detectors for (10^2-10^3)s, potentially offering an opportunity to probe the superkilonova scenario, as well as the lower mass gap between NSs and stellar-mass BHs. However, the complexity of the underlying astrophysics may yield waveforms that deviate from standard templates, limiting the use of matched filtering in real GW searches. We therefore explore the detectability of such signals using the Cross-Correlation Algorithm (CoCoA), a more robust though less sensitive cross-correlation method. We discuss general strategies for implementing CoCoA superkilonova searches via either targeted follow-up of candidate chirps identified in matched-filter searches, or EM-triggered searches of stripped-envelope core-collapse SNe.
