Using failed supernovae to constrain the Galactic r-process element production

The search for failed supernovae with the Large Binocular Telescope: a new candidate and the failed SN fraction with 11 yr of data

We present updated results of the Large Binocular Telescope Search for Failed Supernovae. This search monitors luminous stars in 27 nearby galaxies with a current baseline of 11~yr of data. We re-discover the failed supernova (SN) candidate N6946-BH1 as well as a new candidate, M101-OC1. M101-OC1 is a blue supergiant that rapidly disappears in optical wavelengths with no evidence for significant obscuration by warm dust. While we consider other options, a good explanation for the fading of M101-OC1 is a failed SN, but follow-up observations are needed to confirm this. Assuming only one clearly…

The Search for Failed Supernovae with the Large Binocular Telescope: N6946-BH1, Still No Star

We present new Large Binocular Telescope, Hubble Space Telescope, and Spitzer Space Telescope data for the failed supernova candidate N6946-BH1. We also report an unsuccessful attempt to detect the candidate with Chandra. The ~300,000 Lsun red supergiant progenitor underwent an outburst in 2009 and has since disappeared in the optical. In the LBT data from May 2008 through October 2019, the upper limit on any increase in the R-band luminosity of the source is 2000 Lsun. HST and Spitzer observations show that the source continued to fade in the near-IR and mid-IR, fading by approximately a fact…

The search for failed supernovae with the Large Binocular Telescope: confirmation of a disappearing star

We present Hubble Space Telescope imaging confirming the optical disappearance of the failed supernova (SN) candidate identified by Gerke et al. (2015). This $\sim 25~M_{\odot}$ red supergiant experienced a weak $\sim 10^{6}~L_{\odot}$ optical outburst in 2009 and is now at least 5 magnitudes fainter than the progenitor in the optical. The mid-IR flux has slowly decreased to the lowest levels since the first measurements in 2004. There is faint ($2000-3000~L_{\odot}$) near-IR emission likely associated with the source. We find the late-time evolution of the source to be inconsistent with obscu…

Extragalactic archaeology with the C, N, and O chemical abundances

We predict how the C, N, and O abundances within the interstellar medium of galaxies evolve as functions of the galaxy star formation history (SFH). We adopt a hydrodynamical cosmological simulation, focusing on three star-forming disc galaxies with different SFHs. By assuming failed supernovae, we can predict an increasing trend of the gas-phase N/O--O/H abundance diagram, which was not produced in our previous simulations without failed supernovae. At high redshifts, contrary to the predictions of classical chemical evolution models with instantaneous mixing approximation, we find almost fla…

超新星遗迹中微子背景谱与银河系金属丰度演化

Spectrum of the Supernova Relic Neutrino Background and Metallicity Evolution of Galaxies

计算了过去恒星坍缩（包括黑洞形成）中超新星遗迹中微子（SRN）背景谱。在星系金属丰度演化的基础上，考虑了黑洞形成率与红移的关系。假设失败的超新星祖先的质量和金属丰度的范围内，它们对SRN的贡献是定量估计的第一次。利用该模型，研究了宇宙星形成率密度、激波恢复时间和状态方程对SRN的影响。激波恢复时间作为一个参数，应取决于仍然未知的核心坍缩超新星的爆炸机制。研究了超新星破裂对状态方程的依赖性，超新星的坍缩动力学和中微子发射都受到影响。研究发现，SRN的低能谱主要由宇宙恒星形成率密度决定。这些低能量事件将在超级神冈实验中观察到钆负载水。

From Galactic Chemical Evolution to Cosmic Supernova Rates Synchronized with Core-Collapse Supernovae Limited to the Narrow Progenitor Mass Range

Massive ($\geq$8 $M_\odot$) stars perish via one of two fates: core-collapse supernovae (CCSNe), which release synthesized heavy elements, or failed supernovae, thereby forming black holes. In the conventional Galactic chemical evolution (GCE) scheme, a substantial portion of massive stars, e.g., all stars in the mass range of 8-100 $M_{\odot},$ are assumed to enrich the Galaxy with their nucleosynthetic products. However, this hypothesis conflicts with the observations, namely, few CCSNe whose progenitor stars are more massive than $\sim$18 $M_{\odot}.$ Here, we show that the chemical charact…