Are Kronberger 80 and/or Kronberger 82 regions PeVatron candidates for LHAASO J2108+5157?
Abstract High-energy gamma-rays have been detected in the region of LHAASO J2108+5157 by the Fermi–LAT, HAWC and LHAASO-KM2A observatories. Cygnus OB2 in Cygnus-X has been confirmed as the first strong stellar cluster PeVatron in our Galaxy. Thus, the star-forming regions Kronberger 80 and Kronberger 82, located in the field of LHAASO J2108+5157, are analyzed to evaluate their stellar population and potential as associated PeVatron candidates. A distance of 10 kpc is adopted for Kronberger 80, while $\sim$1.6 kpc is estimated for Kronberger 82. Based on stellar densities, we report that their cluster radii are ${2{^{\prime }_{.}}5}$ and ${2{^{\prime }_{.}}0}$, while infrared photometry reveals poor stellar content in massive O-type stars in both cases. From optical data, the estimations of cluster ages are 5–12.6 and $\lesssim$5 Myr, respectively. We conclude that, in contrast to the stellar content of Cygnus OB2, it is unlikely that Kronberger 80 and Kronberger 82 are PeVatrons associated with LHAASO J2108+5157. The presence of a PeVatron in this region remains a mystery, but we confirm that the two Kronberger regions are star-forming regions undergoing formation rather than evolution.
Authors
- T. Sako (ORCID: https://orcid.org/0000-0002-2589-8561)
- Saurabh Sharma (ORCID: https://orcid.org/0000-0001-5731-3057)
- M. Ohnishi (ORCID: https://orcid.org/0000-0001-5435-4013)
- Akash Gupta (ORCID: https://orcid.org/0000-0002-2006-7769)
- A. Nigoche-Netro (ORCID: https://orcid.org/0000-0002-8683-0982)
- Daniel Tafoya (ORCID: https://orcid.org/0000-0002-2149-2660)
- Iván Toledano–Juárez
- Hiromasa Suzuki (ORCID: https://orcid.org/0000-0002-8152-6172)
- M. A. Trinidad (ORCID: https://orcid.org/0000-0002-9713-6072)
- Harold E Viveros
- K. Kawata (ORCID: https://orcid.org/0000-0001-6332-2005)
- Ram Kesh Yadav (ORCID: https://orcid.org/0000-0002-6740-7425)
- Alicia Porras
- Masato Takita
- Sei Kato
Institutions
- Centre National de la Recherche Scientifique (FR)
- Universidad de Guanajuato (MX)
- University of Cologne (DE)
- Universidad de Guadalajara (MX)
- Japan Aerospace Exploration Agency (JP)
- Institut d'Astrophysique de Paris (FR)
- Aryabhatta Research Institute of Observational Sciences (IN)
- Sorbonne Université (FR)
- National Institute of Astrophysics, Optics and Electronics (MX)
- Institute of Space and Astronautical Science (JP)
- Institute for Cosmic Ray Research (JP)
- Chalmers University of Technology (SE)
- The University of Tokyo (JP)
- National Astronomical Research Institute of Thailand (TH)
Publication Details
- Journal
- Publications of the Astronomical Society of Japan
- Published
- 2025-04-24
- DOI
- https://doi.org/10.1093/pasj/psaf046
- Primary Topic
- Astrophysics and Cosmic Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Astronomical Research Institute of Thailand
- Universidad de Guadalajara
- Ministry of Higher Education, Science, Research and Innovation, Thailand
- Institute for Cosmic Ray Research, University of Tokyo