HAWC, VERITAS, Fermi-LAT, and XMM-Newton Follow-up Observations of the Unidentified Ultra-high-energy Gamma-Ray Source LHAASO J2108+5157
Abstract We report observations of the ultra-high-energy gamma-ray source LHAASO J2108+5157, utilizing VERITAS, HAWC, Fermi-LAT, and XMM-Newton. VERITAS has collected ∼40 hr of data that we used to set ULs to the emission above 200 GeV. The HAWC data, collected over ∼2400 days, reveal emission between 3 and 146 TeV, with a significance of 7.5 σ , favoring an extended source model. The best-fit spectrum measured by HAWC is characterized by a simple power law with a spectral index of 2.45 ± 0.11 stat . Fermi-LAT analysis finds a point source with a very soft spectrum in the LHAASO J2108+5157 region, consistent with the 4FGL-DR3 catalog results. The XMM-Newton analysis yields a null detection of the source in the 2–7 keV band. The broadband spectrum can be interpreted as a pulsar and a pulsar wind nebula system, where the GeV gamma-ray emission originates from an unidentified pulsar, and the X-ray and TeV emissions are attributed to synchrotron radiation and inverse Compton scattering of electrons accelerated within a pulsar wind nebula. In this leptonic scenario, our X-ray upper limit provides a stringent constraint on the magnetic field, which is ≲1.5 μ G.
Authors
- F. Ureña-Mena (ORCID: https://orcid.org/0000-0002-2748-2527)
- Niccolò Di Lalla (ORCID: https://orcid.org/0000-0002-7574-1298)
- P. T. Reynolds
- Miguel Araya (ORCID: https://orcid.org/0000-0002-0595-9267)
- R. Shang (ORCID: https://orcid.org/0000-0002-9856-989X)
- E. Belmont‐Moreno (ORCID: https://orcid.org/0000-0003-3207-105X)
- J. A. Morales-Soto (ORCID: https://orcid.org/0000-0001-9361-0147)
- A. Lara (ORCID: https://orcid.org/0000-0001-6336-5291)
- S. Feldman (ORCID: https://orcid.org/0000-0002-4234-1933)
- Enrique Varela (ORCID: https://orcid.org/0000-0003-0715-7513)
- P. Desiati (ORCID: https://orcid.org/0000-0001-9768-1858)
- W. Hanlon (ORCID: https://orcid.org/0000-0002-0109-4737)
- A. K. Talluri
- D. Tak (ORCID: https://orcid.org/0000-0002-9852-2469)
- E. Moreno (ORCID: https://orcid.org/0000-0002-1114-2640)
- T. K. Kleiner (ORCID: https://orcid.org/0000-0002-4260-9186)
- S. Casanova
- R. W. Springer
- J. A. Matthews
- P. Miranda-Romagnoli (ORCID: https://orcid.org/0000-0002-8390-9011)
- E. De la Fuente (ORCID: https://orcid.org/0000-0001-9643-4134)
- U. Cotti (ORCID: https://orcid.org/0000-0002-7607-9582)
- I. Herzog (ORCID: https://orcid.org/0000-0001-5169-723X)
- A. Nayerhoda
- R. Mukherjee (ORCID: https://orcid.org/0000-0002-3223-0754)
- P. Rabinowitz (ORCID: https://orcid.org/0000-0002-5104-5263)
- Dezhi Huang (ORCID: https://orcid.org/0000-0002-5447-1786)
- Petra Huentemeyer (ORCID: https://orcid.org/0000-0002-3302-7897)
- K. Malone (ORCID: https://orcid.org/0000-0001-8088-400X)
- J. L. Christiansen
- A. Iriarte
- L. Nellen (ORCID: https://orcid.org/0000-0003-1059-8731)
- Michael J. Martin (ORCID: https://orcid.org/0000-0002-6022-217X)
- M. Roth
- M. J. Millard (ORCID: https://orcid.org/0000-0001-7106-8502)
- K. Tollefson
- Jooyun Woo (ORCID: https://orcid.org/0009-0001-6471-1405)
- I. J. Watson
- C. B. Adams (ORCID: https://orcid.org/0000-0002-9021-6192)
- J. H. Buckley (ORCID: https://orcid.org/0000-0001-6391-9661)
- L. Fortson (ORCID: https://orcid.org/0000-0002-1067-8558)
- Y. Son (ORCID: https://orcid.org/0000-0002-7214-8480)
- N. Korzoun (ORCID: https://orcid.org/0000-0002-4289-7106)
- M. J. Lang (ORCID: https://orcid.org/0000-0003-4641-4201)
- M. Lundy (ORCID: https://orcid.org/0000-0003-3802-1619)
- E. Pueschel (ORCID: https://orcid.org/0000-0002-0529-1973)
- R. A. Ong (ORCID: https://orcid.org/0000-0002-4837-5253)
- H. y. Wu (ORCID: https://orcid.org/0000-0001-5928-195X)
- R. Alfaro
- I. Torres (ORCID: https://orcid.org/0000-0002-1689-3945)
- G. Luis-Raya (ORCID: https://orcid.org/0000-0003-2810-4867)
- M. Mostafá
- Kaya Mori (ORCID: https://orcid.org/0000-0002-9709-5389)
- J. Lee
- A. J. Chromey
- E. G. Pérez‐Pérez (ORCID: https://orcid.org/0000-0001-5998-4938)
- W. Benbow (ORCID: https://orcid.org/0000-0003-2098-170X)
- J. V. Tucci
- G. M. Foote (ORCID: https://orcid.org/0000-0002-2944-6060)
- J. A. Goodman
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- Y. Chen
- O. Hervet (ORCID: https://orcid.org/0000-0003-3878-1677)
- Wei Ning (ORCID: https://orcid.org/0000-0002-6121-3443)
- H. León Vargas (ORCID: https://orcid.org/0000-0001-5516-4975)
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- D. Ribeiro (ORCID: https://orcid.org/0000-0002-7523-7366)
- Janeth Valverde (ORCID: https://orcid.org/0000-0002-8090-6528)
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- J. Quinn (ORCID: https://orcid.org/0000-0002-4855-2694)
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- Chang Dong Rho (ORCID: https://orcid.org/0000-0002-6524-9769)
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- F. Hueyotl‐Zahuantitla (ORCID: https://orcid.org/0000-0002-5527-7141)
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- M. A. DuVernois (ORCID: https://orcid.org/0000-0002-2987-9691)
- M. Kertzman
- A. Carramiñana (ORCID: https://orcid.org/0000-0002-8553-3302)
- Samar Safí-Harb (ORCID: https://orcid.org/0000-0001-6189-7665)
- Hongyan Zhou (ORCID: https://orcid.org/0000-0003-4093-2585)
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- C. E. Hinrichs (ORCID: https://orcid.org/0000-0001-6951-2299)
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- J. Cotzomi
- Sergio Hernández Cadena (ORCID: https://orcid.org/0000-0002-2565-8365)
- K. Ragan (ORCID: https://orcid.org/0000-0002-5351-3323)
- Charles J. Hailey (ORCID: https://orcid.org/0000-0002-3681-145X)
- C. de León (ORCID: https://orcid.org/0000-0002-8528-9573)
- D. A. Williams (ORCID: https://orcid.org/0000-0003-2740-9714)
- M. Najafi (ORCID: https://orcid.org/0000-0002-7576-4799)
- J. A. García-González (ORCID: https://orcid.org/0000-0002-4188-5584)
- J. Martínez-Castro
- M. M. González (ORCID: https://orcid.org/0000-0002-5209-5641)
- L. Saha (ORCID: https://orcid.org/0000-0002-3171-5039)
- M. Kherlakian (ORCID: https://orcid.org/0000-0003-4686-0922)
- K. Engel (ORCID: https://orcid.org/0000-0001-5737-1820)
- Kwok Lung Fan (ORCID: https://orcid.org/0000-0002-8246-4751)
- Rhiannon M. Turner (ORCID: https://orcid.org/0000-0003-1068-6707)
- Davide Depaoli (ORCID: https://orcid.org/0000-0002-2672-4141)
- M. Escobar Godoy
- S. Yun-Cárcamo (ORCID: https://orcid.org/0000-0002-9307-0133)
- S. Fraija (ORCID: https://orcid.org/0009-0008-8311-6290)
- Shuo Zhang (ORCID: https://orcid.org/0000-0002-2967-790X)
- O. Martı́nez (ORCID: https://orcid.org/0000-0001-9052-856X)
- Shiqi Yu (ORCID: https://orcid.org/0000-0001-6136-5183)
- W. Jin (ORCID: https://orcid.org/0000-0002-1089-1754)
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- D. Avila Rojas (ORCID: https://orcid.org/0000-0002-4020-4142)
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- G. H. Sembroski (ORCID: https://orcid.org/0000-0003-1329-3909)
- A. J. Smith
- R. Torres-Escobedo
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- M. Schneider
- N. Omodei (ORCID: https://orcid.org/0000-0002-5448-7577)
- S. Groetsch
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Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2025-09-26
- DOI
- https://doi.org/10.3847/1538-4357/adf439
- Citations
- 1
- Primary Topic
- Astrophysics and Cosmic Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 1.87