馬普核物理研究所、都柏林高等研究所Felix Aharonian教授的點評
國際著名粒子天體物理學家，馬普核物理研究所、都柏林高等研究所教授
Over the last two decades, we have seen two revolutions in gamma-ray astronomy: (i) in GeV energy band thanks to the Fermi gamma-ray satellite mission and (ii) at TeV energies after the exploitation of the full potential of the so-called Imaging Atmospheric Cherenkov technique.
These days we are witnessing a new revolution, this time in the UHE, above 100 TeV, band. One can predict with confidence that for the next ten years (at least), LHAASO will dominate in the field and play the major role in the upcoming developments. This is for future.
For the results presented in the published Nature article - we claim the first unbiased and unambiguous discovery of both electron and proton PeVatrons. These are perfectly designed by Nature Cosmic Ray Factories - incredibly efficient machines accelerating particles at a rate close to the absolute theoretical margin determined by the classical electrodynamics and magnetohydrodynamics. At least one source from the published list - Crab Nebula - operates as an Electron PeVatron, and at least one source - Cygnus Cocoon - is powered by a Proton PeVatron. The gamma-ray spectra of both objects continue to and beyond 1 PeV.
Cygnus Cocoon has direct relation to the century-old mystery of the origin of Galactic Cosmic Rays. The famous Cygnus OB stellar cluster inside this diffuse gamma-ray structure is the most likely accelerator supplying Cygnus Cocoon with multi-PeV protons. On the other hand, we do not see in the LHAASO list sources that could be firmly identified with SNRs. This still does not exclude but shakes the standard paradigm which assumes that SNRs are the main contributors to the Galactic Cosmic Rays up to the so-called knee around 1 PeV. On the other hand, the LHAASO results provide a hint that clusters of young, very-massive stars should be considered a serious alternative or addition to SNRs. Moreover, using the chess language, I would say that in the PeVatron competition “young stars versus dead stars”, the score is 1:0 in favour of young stars.
Finally, let me conclude with a statement that the results reported in the Nature article reveal only the tip of the iceberg. In the coming years, we anticipate breakthrough discoveries by LHAASO that could dramatically change the current concepts about the most energetic and extreme phenomena in the non-thermal Universe.
在過去的二十年多中，伽馬射線天文學經歷了兩次革新：其一在GeV能量段由Fermi-LAT伽馬射線衛(wèi)星所帶來，其二在TeV能量段藉由對成像大氣切倫科夫望遠鏡潛力的最大化利用而產生。如今，我們正在見證另一場發(fā)生在超高能量段(100TeV之上)的革新。人們可以信心十足地預測，在未來至少十年的時間里，LHAASO將在伽馬射線天文學領域鰲頭獨占，并在該領域未來的發(fā)展中發(fā)揮主要作用。
LHAASO團隊在《自然》雜志上發(fā)表的這篇最新論文里，首次報導了對PeV電子加速源與PeV質子加速源客觀且明確的探測。這些完美的宇宙線工廠誕生于宇宙的鬼斧神工。它們加速粒子的效率驚人，直逼由經典電動力學與磁流體力學決定的絕對理論上限。在發(fā)布的加速源列表中，可以確認其中至少有一個天體——蟹狀星云——作為PeV電子加速器在運行，也至少有一個天體——天鵝座繭——由PeV質子加速器供能。這兩個天體的伽馬射線能譜都延續(xù)到了1 PeV之上。
天鵝座繭與銀河宇宙線起源這個物理學界的世紀謎題有著直接關聯(lián)。位于這團彌散伽馬射線結構體中心的天鵝座OB星團是最有可能的PeV宇宙線質子加速器。另一方面，超新星遺跡卻未明確見于LHAASO發(fā)布的源表之中。這動搖了——盡管仍能未排除——超新星遺跡作為銀河系中能量上至所謂膝區(qū)的PeV宇宙線的主要加速源的標準范式。同時，LHAASO也帶來了年輕大質量恒星團作為超新星遺跡的替代或補充的新線索。若以國際象棋的術語來說，在這場“年輕恒星對死亡恒星”的較量中，年輕恒星正以1：0領先。
作為總結，我想說這篇《自然》上的論文揭開的僅僅是冰山一角。我們期待在未來幾年，LHAASO的突破性發(fā)現(xiàn)可能會使得我們目前對非熱宇宙中那些最活躍最極端現(xiàn)象的觀念發(fā)生極大的改變。
附件下載：