HAWC, VERITAS, Fermi-LAT, and XMM-Newton Follow-up Observations of the Unidentified Ultra-high-energy Gamma-Ray Source LHAASO J2108+5157

VERITAS Collaboration; HAWC Collaboration; XMM-Newton collaboration

doi:10.3847/1538-4357/adf439

HAWC, VERITAS, Fermi-LAT, and XMM-Newton Follow-up Observations of the Unidentified Ultra-high-energy Gamma-Ray Source LHAASO J2108+5157

VERITAS Collaboration
, HAWC Collaboration
, XMM-Newton collaboration

Department of Physics

Research output: Contribution to journal › Article › peer-review

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 7.5σ, 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 μG.

Original language	English
Journal	Astrophysical Journal
Volume	991
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/adf439
State	Published - Oct 1 2025

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10.3847/1538-4357/adf439

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@article{8284503bec5d4d6e9ec45b487ad1b0d2,

title = "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 7.5σ, 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 ± 0.11stat. 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 μG.",

author = "\{VERITAS Collaboration\} and \{HAWC Collaboration\} and \{XMM-Newton collaboration\} and Adams, \{C. B.\} and P. Bangale and W. Benbow and Buckley, \{J. H.\} and Y. Chen and Christiansen, \{J. L.\} and Chromey, \{A. J.\} and \{Escobar Godoy\}, M. and S. Feldman and Q. Feng and J. Foote and L. Fortson and A. Furniss and W. Hanlon and O. Hervet and Hinrichs, \{C. E.\} and J. Holder and Z. Hughes and Humensky, \{T. B.\} and W. Jin and P. Kaaret and M. Kertzman and M. Kherlakian and D. Kieda and Kleiner, \{T. K.\} and N. Korzoun and S. Kumar and Lang, \{M. J.\} and M. Lundy and G. Maier and Millard, \{M. J.\} and P. Moriarty and R. Mukherjee and W. Ning and Ong, \{R. A.\} and M. Pohl and E. Pueschel and J. Quinn and Rabinowitz, \{P. L.\} and K. Ragan and Reynolds, \{P. T.\} and D. Ribeiro and E. Roache and I. Sadeh and L. Saha and Sembroski, \{G. H.\} and R. Shang and D. Tak and Talluri, \{A. K.\} and Tucci, \{J. V.\} and J. Valverde and Williams, \{D. A.\} and Wong, \{S. L.\} and J. Woo and R. Alfaro and C. Alvarez and Arteaga-Vel{\'a}zquez, \{J. C.\} and \{Avila Rojas\}, D. and R. Babu and E. Belmont-Moreno and A. Bernal and Caballero-Mora, \{K. S.\} and A. Carrami{\~n}ana and S. Casanova and U. Cotti and J. Cotzomi and \{De la Fuente\}, E. and \{de Le{\'o}n\}, C. and D. Depaoli and P. Desiati and \{Di Lalla\}, N. and \{Diaz Hernandez\}, R. and DuVernois, \{M. A.\} and K. Engel and T. Ergin and C. Espinoza and Fan, \{K. L.\} and N. Fraija and S. Fraija and Garc{\'i}a-Gonz{\'a}lez, \{J. A.\} and F. Garfias and \{Gonzalez Mu{\~n}oz\}, A. and Gonz{\'a}lez, \{M. M.\} and Goodman, \{J. A.\} and S. Groetsch and Harding, \{J. P.\} and S. Hern{\'a}ndez-Cadena and I. Herzog and D. Huang and F. Hueyotl-Zahuantitla and P. H{\"u}ntemeyer and A. Iriarte and S. Kaufmann and A. Lara and J. Lee and \{Le{\'o}n Vargas\}, H. and Longinotti, \{A. L.\} and G. Luis-Raya and K. Malone and O. Martinez and J. Mart{\'i}nez-Castro and Matthews, \{J. A.\} and P. Miranda-Romagnoli and Morales-Soto, \{J. A.\} and E. Moreno and M. Araya and M. Mostaf{\'a} and M. Najafi and A. Nayerhoda and L. Nellen and N. Omodei and E. Ponce and P{\'e}rez-P{\'e}rez, \{E. G.\} and Rho, \{C. D.\} and D. Rosa-Gonz{\'a}lez and M. Roth and H. Salazar and A. Sandoval and M. Schneider and J. Serna-Franco and Smith, \{A. J.\} and Y. Son and Springer, \{R. W.\} and O. Tibolla and K. Tollefson and I. Torres and R. Torres-Escobedo and R. Turner and F. Ure{\~n}a-Mena and E. Varela and L. Villase{\~n}or and X. Wang and Z. Wang and Watson, \{I. J.\} and H. Wu and S. Yu and S. Yun-C{\'a}rcamo and H. Zhou and M. Martin and Kaya Mori and Hailey, \{Charles J.\} and Samar Safi-Harb and Shuo Zhang",

note = "Publisher Copyright: {\textcopyright} 2025. The Author(s). Published by the American Astronomical Society.",

year = "2025",

month = oct,

day = "1",

doi = "10.3847/1538-4357/adf439",

language = "English",

volume = "991",

journal = "Astrophysical Journal",

issn = "0004-637X",

number = "2",

}

TY - JOUR

T1 - HAWC, VERITAS, Fermi-LAT, and XMM-Newton Follow-up Observations of the Unidentified Ultra-high-energy Gamma-Ray Source LHAASO J2108+5157

AU - VERITAS Collaboration

AU - HAWC Collaboration

AU - XMM-Newton collaboration

AU - Adams, C. B.

AU - Bangale, P.

AU - Benbow, W.

AU - Buckley, J. H.

AU - Chen, Y.

AU - Christiansen, J. L.

AU - Chromey, A. J.

AU - Escobar Godoy, M.

AU - Feldman, S.

AU - Feng, Q.

AU - Foote, J.

AU - Fortson, L.

AU - Furniss, A.

AU - Hanlon, W.

AU - Hervet, O.

AU - Hinrichs, C. E.

AU - Holder, J.

AU - Hughes, Z.

AU - Humensky, T. B.

AU - Jin, W.

AU - Kaaret, P.

AU - Kertzman, M.

AU - Kherlakian, M.

AU - Kieda, D.

AU - Kleiner, T. K.

AU - Korzoun, N.

AU - Kumar, S.

AU - Lang, M. J.

AU - Lundy, M.

AU - Maier, G.

AU - Millard, M. J.

AU - Moriarty, P.

AU - Mukherjee, R.

AU - Ning, W.

AU - Ong, R. A.

AU - Pohl, M.

AU - Pueschel, E.

AU - Quinn, J.

AU - Rabinowitz, P. L.

AU - Ragan, K.

AU - Reynolds, P. T.

AU - Ribeiro, D.

AU - Roache, E.

AU - Sadeh, I.

AU - Saha, L.

AU - Sembroski, G. H.

AU - Shang, R.

AU - Tak, D.

AU - Talluri, A. K.

AU - Tucci, J. V.

AU - Valverde, J.

AU - Williams, D. A.

AU - Wong, S. L.

AU - Woo, J.

AU - Alfaro, R.

AU - Alvarez, C.

AU - Arteaga-Velázquez, J. C.

AU - Avila Rojas, D.

AU - Babu, R.

AU - Belmont-Moreno, E.

AU - Bernal, A.

AU - Caballero-Mora, K. S.

AU - Carramiñana, A.

AU - Casanova, S.

AU - Cotti, U.

AU - Cotzomi, J.

AU - De la Fuente, E.

AU - de León, C.

AU - Depaoli, D.

AU - Desiati, P.

AU - Di Lalla, N.

AU - Diaz Hernandez, R.

AU - DuVernois, M. A.

AU - Engel, K.

AU - Ergin, T.

AU - Espinoza, C.

AU - Fan, K. L.

AU - Fraija, N.

AU - Fraija, S.

AU - García-González, J. A.

AU - Garfias, F.

AU - Gonzalez Muñoz, A.

AU - González, M. M.

AU - Goodman, J. A.

AU - Groetsch, S.

AU - Harding, J. P.

AU - Hernández-Cadena, S.

AU - Herzog, I.

AU - Huang, D.

AU - Hueyotl-Zahuantitla, F.

AU - Hüntemeyer, P.

AU - Iriarte, A.

AU - Kaufmann, S.

AU - Lara, A.

AU - Lee, J.

AU - León Vargas, H.

AU - Longinotti, A. L.

AU - Luis-Raya, G.

AU - Malone, K.

AU - Martinez, O.

AU - Martínez-Castro, J.

AU - Matthews, J. A.

AU - Miranda-Romagnoli, P.

AU - Morales-Soto, J. A.

AU - Moreno, E.

AU - Araya, M.

AU - Mostafá, M.

AU - Najafi, M.

AU - Nayerhoda, A.

AU - Nellen, L.

AU - Omodei, N.

AU - Ponce, E.

AU - Pérez-Pérez, E. G.

AU - Rho, C. D.

AU - Rosa-González, D.

AU - Roth, M.

AU - Salazar, H.

AU - Sandoval, A.

AU - Schneider, M.

AU - Serna-Franco, J.

AU - Smith, A. J.

AU - Son, Y.

AU - Springer, R. W.

AU - Tibolla, O.

AU - Tollefson, K.

AU - Torres, I.

AU - Torres-Escobedo, R.

AU - Turner, R.

AU - Ureña-Mena, F.

AU - Varela, E.

AU - Villaseñor, L.

AU - Wang, X.

AU - Wang, Z.

AU - Watson, I. J.

AU - Wu, H.

AU - Yu, S.

AU - Yun-Cárcamo, S.

AU - Zhou, H.

AU - Martin, M.

AU - Mori, Kaya

AU - Hailey, Charles J.

AU - Safi-Harb, Samar

AU - Zhang, Shuo

PY - 2025/10/1

Y1 - 2025/10/1

N2 - 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 7.5σ, 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 ± 0.11stat. 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 μG.

AB - 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 7.5σ, 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 ± 0.11stat. 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 μG.

UR - https://www.scopus.com/pages/publications/105017507744

U2 - 10.3847/1538-4357/adf439

DO - 10.3847/1538-4357/adf439

M3 - Article

AN - SCOPUS:105017507744

SN - 0004-637X

VL - 991

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

ER -

HAWC, VERITAS, Fermi-LAT, and XMM-Newton Follow-up Observations of the Unidentified Ultra-high-energy Gamma-Ray Source LHAASO J2108+5157

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