2025ApJ...987L..42A

Query : 2025ApJ...987L..42A

2025ApJ...987L..42A - Astrophys. J., 987, L42 (2025/July-2)

Orbital Modulation of Gamma Rays up to 100 TeV from LS 5039.

ALFARO R., ARAYA M., ARTEAGA-VELAZQUEZ J.C., AVILA ROJAS D., AYALA SOLARES H.A., BABU R., BANGALE P., BELMONT-MORENO E., BERNAL A., CABALLERO-MORA K.S., CAPISTRAN T., CARRAMINANA A., CASANOVA S., COTTI U., COTZOMI J., COUTINO DE LEON S., DEPAOLI D., DESIATI P., DI LALLA N., DIAZ HERNANDEZ R., DINGUS B.L., DUVERNOIS M.A., ENGEL K., ERGIN T., ESPINOZA C., FAN K.L., FANG K., GARCIA-GONZALEZ J.A., GOKSU H., GONZALEZ MUNOZ A., GONZALEZ J.A., GONZALEZ M.M., GOODMAN J.A., GROETSCH S., HARDING J.P., HERNANDEZ-CADENA S., HERZOG I., HINTON J., HUANG D., HUEYOTL-ZAHUANTITLA F., HUNTEMEYER P., KAUFMANN S., KIEDA D., LARA A., LEE J., LEON VARGAS H., LINNEMANN J.T., LONGINOTTI A.L., LUIS-RAYA G., MALONE K., MARTINEZ O., MARTINEZ-CASTRO J., MATTHEWS J.A., MIRANDA-ROMAGNOLI P., MORALES-SOTO J.A., MORENO E., MOSTAFA M., NAJAFI M., NELLEN L., NISA M.U., OMODEI N., PONCE E., PEREZ ARAUJO Y., PEREZ-PEREZ E.G., RHO C.D., RODRIGUEZ PARRA A., ROSA-GONZALEZ D., ROTH M., SALAZAR H., SALAZAR-GALLEGOS D., SANDOVAL A., SCHNEIDER M., SCHWEFER G., SERNA-FRANCO J., SMITH A.J., SON Y., SPRINGER R.W., TIBOLLA O., TOLLEFSON K., TORRES I., TORRES-ESCOBEDO R., TURNER R., VARELA E., WANG X., WANG Z., WATSON I.J., WU H., YU S., YUN-CARCAMO S., ZHOU H., DE LEON C. (The HAWC Collaboration)

Abstract (from CDS):

Gamma-ray binaries are luminous in gamma rays, composed of a compact object orbiting a massive companion star. The interaction between these two objects can drive relativistic outflows, either jets or winds, in which particles can be accelerated to energies reaching hundreds of teraelectronvolts (TeV). However, it is still debated where and under which physical conditions particles are accelerated in these objects and ultimately whether protons can be accelerated up to PeV energies. Among the well-known gamma-ray binaries, LS 5039 is a high-mass X-ray binary with an orbital period of 3.9 days that has been observed up to TeV energies by the High Energy Stereoscopic System. We present new observations of LS 5039 obtained with the High Altitude Water Cherenkov (HAWC) observatory. Our data reveal that the gamma-ray spectrum of LS 5039 extends up to 200 TeV with no apparent spectral cutoff. Furthermore, we confirm, with a confidence level of 4.7σ, that the emission between 2 and 118 TeV is modulated by the orbital motion of the system, and find a 2.2σ hint of variability above 100 TeV. This indicates that these photons are likely produced within or near the binary orbit, where they can undergo absorption by the stellar photons. In a leptonic scenario, the highest energy photons detected by HAWC can be emitted by ∼200 TeV electrons inverse Compton scattering stellar photons, which would require an extremely efficient acceleration mechanism operating within LS 5039. Alternatively, a hadronic scenario could explain the data through proton-proton or proton-gamma collisions of protons accelerated to petaelectronvolt energies.

Abstract Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Gamma-ray observatories - Gamma-ray sources - High energy astrophysics - High mass x-ray binary stars

Simbad objects: 9

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Number of rows : 9
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 eHWC J1825-134 gam 18 25.0 -13 26           ~ 21 0
2 HAWC J1825-140 gam 18 25.2 -14 03           ~ 1 0
3 HAWC J1825-130 gam 18 25.9 -12 58           ~ 1 0
4 HAWC J1825-136 gam 18 26.0 -13 38           ~ 1 0
5 HAWC J1825-125 gam 18 26.0 -12 31           ~ 1 0
6 PSR J1826-1256 Psr 18 26 08.570 -12 56 33.53           ~ 152 1
7 HAWC J1826-148 gam 18 26.2 -14 49           ~ 1 0
8 PSR B1823-13 Psr 18 26 13.06 -13 34 48.1           ~ 460 1
9 V* V479 Sct HXB 18 26 15.0561548880 -14 50 54.247274304 12.02 12.23 11.27 11.04   ON6V((f))z 613 2

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