Ultrahigh-energy gamma rays and gravitational waves from primordial exotic stellar bubbles

Yi-Fu Cai; Chao Chen; Qianhang Ding; Yi Wang

doi:10.1140/epjc/s10052-022-10395-w

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2022) 82: 464
https://doi.org/10.1140/epjc/s10052-022-10395-w

Regular Article - Theoretical Physics

Ultrahigh-energy gamma rays and gravitational waves from primordial exotic stellar bubbles

Yi-Fu Cai¹^,2^,3, Chao Chen¹^,4^b, Qianhang Ding⁴^,5 and Yi Wang⁴^,5

¹ Department of Astronomy, School of Physical Sciences, University of Science and Technology of China, 230026, Hefei, Anhui, People’s Republic of China
² School of Astronomy and Space Science, University of Science and Technology of China, 230026, Hefei, Anhui, People’s Republic of China
³ CAS Key Laboratory for Research in Galaxies and Cosmology, University of Science and Technology of China, 230026, Hefei, Anhui, People’s Republic of China
⁴ Jockey Club Institute for Advanced Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China
⁵ Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China

^b iascchao@ust.hk

Received: 28 March 2022
Accepted: 30 April 2022
Published online: 20 May 2022

Abstract

We put forward a novel class of exotic celestial objects that can be produced through phase transitions occurring in the primordial Universe. These objects appear as bubbles of stellar size and can be dominated by primordial black holes (PBHs). We report that, due to the processes of Hawking radiation and binary evolution of PBHs inside these stellar bubbles, both electromagnetic and gravitational radiations can be emitted that are featured on the gamma-ray spectra and stochastic gravitational waves (GWs). Our results reveal that, depending on the mass distribution, the exotic stellar bubbles consisting of PBHs not only provide a decent fit for the ultrahigh-energy gamma-ray spectrum reported by the recent LHAASO experiment, but also predict GW signals that are expected to be tested by the forthcoming GW surveys.

© The Author(s) 2022

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