Response to Comment on "A Non-Interacting Low-Mass Black Hole -- Giant Star Binary System"

Comment on "A non-interacting low-mass black hole -- giant star binary system"

Thompson et al. (Reports, 1 November 2019, p. 637, Science) interpreted the unseen companion of the red giant star 2MASS J05215658+4359220 as most likely a black hole. We argue that if the red giant is about one solar mass, its companion can be a close binary consisting of two main-sequence stars. This would explain why no X-ray emission is detected from the system.

相对论激波的非热辐射：对与AGN喷流相互作用的红巨星风的应用

Non-thermal emission from standing relativistic shocks: an application to red giant winds interacting with AGN jets

银河系和河外相对论喷流有着丰富的环境，充满了移动的物体，如恒星和致密的团块。这些物体可以进入射流并产生冲击和非热发射。本文描述了由相对论性喷流与障碍物相互作用形成的驻激波下游区域的发射特性。我们专注于红巨星与河外喷流相互作用的情况。我们进行相对论性轴对称流体动力学模拟的相对论性喷流满足非常大的惯性障碍。结果解释的框架下的红巨星的密集和缓慢的风相互作用的喷流的活动星系核。假设粒子在射流冲击红巨星风时产生的驻激波中加速，我们计算了非热粒子分布、多普勒增强和伽马射线的非热光度。当考虑由障碍物引起的冲击的整个表面而不是仅考虑障碍物部分时，来自射流-障碍物相互作用的可用非热能潜在地增强了$\sim 100$的因子。观测者的伽马射线亮度，包括流速和多普勒增强效应，可以比假设发射流静止且只考虑障碍物截面时高约300（g/10）^2倍，其中g是喷流洛伦兹因子。对于活动星系核喷流内的全部红巨星，预测的持续伽马射线光度可能是指向观测者的喷流潜在可探测的。在研究这些来源的非热辐射时，应考虑到与相对论性外流相互作用的障碍物，例如河外喷流的星云和恒星群，或微类星体喷流中的恒星风不均匀性和双星中类星体风的不均匀性。

A Unicorn in Monoceros: the $3M_\odot$ dark companion to the bright, nearby red giant V723 Mon is a non-interacting, mass-gap black hole candidate

We report the discovery of the closest known black hole candidate as a binary companion to V723 Mon. V723 Mon is a nearby ($d\sim460\,\rm pc$), bright ($V\simeq8.3$~mag), evolved ($T_{\rm eff, giant}\simeq4440$~K, and $L_{\rm giant}\simeq173~L_\odot$) red giant in a high mass function, $f(M)=1.72\pm 0.01~M_\odot$, nearly circular binary ($P=59.9$ d, $e\simeq 0$). V723 Mon is a known variable star, previously classified as an eclipsing binary, but its All-Sky Automated Survey (ASAS), Kilodegree Extremely Little Telescope (KELT), and Transiting Exoplanet Survey Satellite (TESS) light curves are …

云和红巨星与AGN喷流底部相互作用

Clouds and red giants interacting with the base of AGN jets

河外喷流形成于星系中心的超大质量黑洞附近。大量的气体、尘埃和恒星聚集在星系核中，这些周围的物质和喷流基底之间的相互作用应该是频繁的，具有动力学和辐射的后果。这项工作研究了一个障碍物、一团物质或一颗演化恒星的大气层与河外喷流最内部区域的动力学相互作用。射流质量负荷和这种相互作用的高能量的结果进行了简要讨论。对相对论性喷流中的均匀和非均匀障碍物进行了轴对称相对论流体动力学模拟。这些障碍物可能代表一种中等的不均匀性，或者是红巨星大气层的破裂。一旦进入喷流，一个均匀的障碍物会膨胀，并在几个动力学时间尺度后被破坏，而在非均匀的情况下，一个固体核心可以平滑这个过程，障碍物的质量损失主要由指向喷流方向的密集而狭窄的尾部控制。在这两种情况下，物质都有望加速并最终融入喷气式飞机。粒子可以在相互作用区被加速，并在周围物质、磁场和光子场中产生可变的伽马射线。物质团块或红巨星进入河外喷流底部的存在可能意味着显著的喷流质量加载和减速。由于这些相互作用，预计会出现类似耀斑的快速伽马射线事件和某种程度的持续发射。

Spectral Flattening at Low Frequencies in Crab Giant Pulses

We report on simultaneous wideband observations of Crab giant pulses with the Parkes radio telescope and the Murchison Widefield Array (MWA). The observations were conducted simultaneously at 732 and 3100 MHz with Parkes, and at 120.96, 165.76 and 210.56 MHz with the MWA. Flux density calibration of the MWA data was accomplished using a novel technique based on tied-array beam simulations. We detected between 90-648 giant pulses in the 120.96-210.56 MHz MWA subbands above a $ 5.5σ$ threshold while in the Parkes subbands we detected 6344 and 231 giant pulses above a threshold of $ 6σ$ at 732 an…