Morphology of young massive stellar clusters with next-generation IACTs

IF 10.5 4区物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS

Journal of High Energy Astrophysics Pub Date : 2025-09-16 DOI:10.1016/j.jheap.2025.100465

A. Bonollo , P. Esposito , A. Giuliani , P. Caraveo , G. Galanti , S. Crestan , M. Rigoselli , S. Mereghetti

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引用次数: 0

Abstract

The term PeVatron designates astrophysical objects capable of accelerating particles to PeV energies (1 PeV = 10¹⁵ eV). Their nature and particle acceleration mechanisms are uncertain, but ultra-high-energy gamma rays (>100 TeV) are produced when particles accelerated by either leptonic and hadronic PeVatrons interact with the surrounding medium or radiation fields. The atmospheric air shower observatory LHAASO detected photons with energies above 100 TeV from 43 sources in the Galactic Plane, proving the existence of PeVatrons within the Milky Way. In particular, one of the detections was a 1.4 PeV photon in spatial correspondence with Cygnus OB2, providing a strong hint that young massive stellar clusters (YMSCs) can act as PeVatrons.

The next-generation ground-based Cherenkov telescopes will have unprecedented energy and angular resolution. Therefore, they will be able to resolve spatially YMSCs better than LHAASO. We focused on a sample of 5 YMSCs and their environments visible from either hemisphere with the CTAO or ASTRI Mini-Array. We modelled the secondary gamma-ray emission above 1 TeV and simulated observations of all sources. We devised methods for classifying YMSCs that could be detected as unidentified extended TeV sources and estimate the observational time needed to distinguish the morphology of different classes of sources.

We study the morphology of the sources in our sample in order to identify their main features. We simulated observations of all sources with the instrument response function (IRF) of CTAO or ASTRI Mini-Array. We compare their emission distribution to the one of the TeV halos observed by HAWC. We parametrize their radial profiles in order to develop methodologies to classify them and to distinguish YMSCs from TeV halos based on their morphology. We expect some feature, such as the emission peak, to be key in differentiating between the two classes of objects. We then test them on a sample of sources of the first LHAASO catalogue.

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用下一代IACTs观察年轻大质量星团的形态

PeVatron这个术语指的是能够将粒子加速到PeV能量（1 PeV = 1015 eV）的天体物理物体。它们的性质和粒子加速机制尚不确定，但当粒子被轻子和强子pevatron加速与周围介质或辐射场相互作用时，就会产生超高能伽马射线（100 TeV）。大气雨淋天文台LHAASO探测到来自银道面的43个源的能量超过100 TeV的光子，证明了银河系中存在pevatron。特别是，其中一个探测到的是与天鹅座OB2空间对应的1.4 PeV光子，这有力地暗示了年轻的大质量星团（YMSCs）可以充当pevatron。下一代地面切伦科夫望远镜将拥有前所未有的能量和角度分辨率。因此，它们能够比LHAASO更好地分辨空间YMSCs。我们集中研究了5个YMSCs的样本和它们的环境，用CTAO或应科院Mini-Array从两个半球可见。我们模拟了1 TeV以上的二次伽玛射线发射，并模拟了所有源的观测结果。我们设计了对YMSCs进行分类的方法，这些YMSCs可以被检测为未识别的扩展TeV源，并估计了区分不同类型源形态所需的观察时间。我们研究了样品中源的形态，以确定它们的主要特征。我们用CTAO或应科院Mini-Array的仪器响应函数（IRF）模拟了所有源的观测结果。我们将它们的发射分布与HAWC观测到的TeV光晕进行了比较。我们参数化它们的径向轮廓，以便开发方法来对它们进行分类，并根据它们的形态区分YMSCs和TeV晕。我们期望一些特征，如发射峰值，是区分两类物体的关键。然后，我们在第一个LHAASO目录的来源样本上对它们进行测试。

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来源期刊

Journal of High Energy Astrophysics Earth and Planetary Sciences-Space and Planetary Science

CiteScore

9.70

自引率

5.30%

发文量

审稿时长

65 days

期刊介绍： The journal welcomes manuscripts on theoretical models, simulations, and observations of highly energetic astrophysical objects both in our Galaxy and beyond. Among those, black holes at all scales, neutron stars, pulsars and their nebula, binaries, novae and supernovae, their remnants, active galaxies, and clusters are just a few examples. The journal will consider research across the whole electromagnetic spectrum, as well as research using various messengers, such as gravitational waves or neutrinos. Effects of high-energy phenomena on cosmology and star-formation, results from dedicated surveys expanding the knowledge of extreme environments, and astrophysical implications of dark matter are also welcomed topics.