近日，墨西哥国立大学的R. Alfaro及其研究小组与波兰科学院核物理研究所的S. Casanova等人合作并取得一项新进展。他们对微类星体V4641 Sgr周围的超高能伽玛射线泡进行了研究。相关研究成果已于2024年10月16日在国际权威学术期刊《自然》上发表。

据悉，微类星体是研究旋转黑洞吸积过程中产生的相对论性粒子喷流的天然实验室。这些微类星体距离人类足够近，使得研究人员能够跨越多波长光谱对其空间特征进行详细成像。最近对微类星体SS433空间形态的测量扩展至万亿电子伏特（TeV）伽马射线，揭示了远离黑洞的喷流中电子在冲击波处的加速位置。

V4641射手座（V4641Sgr）是一个类似的双星系统，包含一个黑洞和一颗B型主序伴星，轨道周期为2.8天。该系统以其超爱丁顿吸积和射电喷流而著称，其喷流是银河系中最快的超光速喷流之一。以往对V4641Sgr的观测中并未报告伽马射线辐射。

本文报道了V4641Sgr发出的万亿电子伏特（TeV）伽马射线，揭示了与SS433类似的、距黑洞相当远处的粒子加速现象。此外，V4641Sgr的伽马射线能谱是已知伽马射线源中观测到的最硬的TeV能谱之一，且其探测能量超过200 TeV。

伽马射线是由高能粒子（电子或质子）产生的。由于能量越高的电子能量损失越快，因此这样的能谱要么对电子产生机制构成了极强的限制，要么暗示了高能质子的加速。这表明，微类星体产生的大规模喷流可能比先前预期的更为普遍，并且它们可能是银河系宇宙射线的重要来源。

附：英文原文

Title: Ultra-high-energy gamma-ray bubble around microquasar V4641 Sgr

Author: Alfaro, R., Alvarez, C., Arteaga-Velzquez, J. C., Avila Rojas, D., Ayala Solares, H. A., Babu, R., Belmont-Moreno, E., Caballero-Mora, K. S., Capistrn, T., Carramiana, A., Casanova, S., Cotti, U., Cotzomi, J., Coutio de Len, S., De la Fuente, E., Depaoli, D., Di Lalla, N., Diaz Hernandez, R., Dingus, B. L., DuVernois, M. A., Durocher, M., Daz-Vlez, J. C., Engel, K., Espinoza, C., Fan, K. L., Fang, K., Fraija, N., Fraija, S., Garca-Gonzlez, J. A., Garfias, F., Gonzalez Muoz, A., Gonzlez, M. M., Goodman, J. A., Groetsch, S., Harding, J. P., Herzog, I., Hinton, J., Huang, D., Hueyotl-Zahuantitla, F., Hntemeyer, P., Iriarte, A., Joshi, V., Kaufmann, S., Kieda, D., de Len, C., Lee, J., Len Vargas, H., Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., Malone, K., Martinez, O., Martnez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostaf, M., Nayerhoda, A., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Olivera-Nieto, L., Omodei, N., Osorio, M., Prez Araujo, Y., Prez-Prez, E. G., Rho, C. D., Rosa-Gonzlez, D., Ruiz-Velasco, E., Salazar, H., Salazar-Gallegos, D., Sandoval, A., Schneider, M.

Issue&Volume: 2024-10-16

Abstract: Microquasars are laboratories for the study of jets of relativistic particles produced by accretion onto a spinning black hole. Microquasars are near enough to allow detailed imaging of spatial features across the multiwavelength spectrum. The recent extension measurement of the spatial morphology of a microquasar, SS433, to TeV gamma rays localizes the acceleration of electrons at shocks in the jet far from the black hole. V4641Sagittarii (V4641Sgr) is a similar binary system with a black hole and B-type main-sequence companion star and has an orbit period of 2.8days . It stands out for its super-Eddington accretion and for its radio jet, which is one of the fastest superluminal jets in the Milky Way. Previous observations of V4641Sgr did not report gamma-ray emission. Here we report TeV gamma-ray emission from V4641Sgr that reveals particle acceleration at similar distances from the black hole as SS433. Furthermore, the gamma-ray spectrum of V4641Sgr is among the hardest TeV spectra observed from any known gamma-ray source and is detected above 200TeV. Gamma rays are produced by particles, either electrons or protons, of higher energies. Because energetic electrons lose energy more quickly the higher their energy, such a spectrum either very strongly constrains the electron-production mechanism or points to the acceleration of high-energy protons. This suggests that large-scale jets from microquasars could be more common than previously expected and that they could be a notable source of galactic cosmic rays.

DOI: 10.1038/s41586-024-07995-9

Source: https://www.nature.com/articles/s41586-024-07995-9