Discovery of the Ultrahigh-energy Gamma-Ray Source LHAASO J2108+5157
Creators
- 1. Key Laboratory of Particle Astrophysics & Experimental Physics Division & Computing Center, Institute of High Energy Physics, Chinese Academy of Sciences, 100049 Beijing (China)
- 2. Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, 2 Dublin (Ireland)
- 3. State Key Laboratory of Particle Detection and Electronics (China)
- 4. School of Physical Science and Technology & School of Information Science and Technology, Southwest Jiaotong University, 610031 Chengdu, Sichuan (China)
- 5. College of Physics, Sichuan University, 610065 Chengdu, Sichuan (China)
- 6. School of Astronomy and Space Science, Nanjing University, 210023 Nanjing, Jiangsu (China)
- 7. Center for Astrophysics, Guangzhou University, 510006 Guangzhou, Guangdong (China)
- 8. School of Physics and Technology, Wuhan University, 430072 Wuhan, Hubei (China)
- 9. Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, 210023 Nanjing, Jiangsu (China)
- 10. Hebei Normal University, 050024 Shijiazhuang, Hebei (China)
Description
We report the discovery of an ultrahigh-energy (UHE) gamma-ray source, LHAASO J2108+5157, by analyzing the LHAASO-KM2A data of 308.33 live days. A significant excess of gamma ray–induced showers is observed in both energy bands of 25−100 and >100 TeV with 9.5σ and 8.5σ, respectively. This source is not significantly favored as an extended source with an angular extension smaller than the point-spread function of KM2A. The measured energy spectrum from 20 to 200 TeV can be approximately described by a power-law function with an index of −2.83 ± 0.18stat. A harder spectrum is demanded at lower energies considering the flux upper limit set by Fermi-LAT observations. The position of the gamma-ray emission is correlated with a giant molecular cloud, which favors a hadronic origin. No obvious counterparts have been found, and deeper multiwavelength observations will help to cast new light on this intriguing UHE source.
Availability note (English)
Available from http://dx.doi.org/10.3847/2041-8213/ac2579Additional details
Identifiers
Publishing Information
- Journal Title
- Astrophysical Journal Letters
- Journal Volume
- 919
- Journal Issue
- 2
- Journal Page Range
- [9 p.]
- ISSN
- 2041-8205
INIS
- Country of Publication
- United Kingdom
- Country of Input or Organization
- International Atomic Energy Agency (IAEA)
- INIS RN
- 53072185
- Subject category
- S79: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY;
- Descriptors DEI
- COSMIC GAMMA SOURCES; EMISSION; ENERGY SPECTRA; GAMMA RADIATION
- Descriptors DEC
- COSMIC RAY SOURCES; ELECTROMAGNETIC RADIATION; IONIZING RADIATIONS; RADIATIONS; SPECTRA