HAWC Search for High-mass Microquasars

Microquasars with high-mass companion stars are promising very-high-energy (VHE; 0.1-100 TeV) gamma-ray emitters, but their behaviors above 10 TeV poorly known. Using the High Altitude Water Cherenkov (HAWC) observatory, we search for excess emission coincident positions of known microquasars (HMMQs). No significant is observed LS 5039, Cygnus X-1, X-3, and SS 433 1,523 days HAWC data. We set most stringent limit obtained to date on each individual source. Under assumption that HMMQs produce gamma rays via a common mechanism, have performed source-stacking searches, considering two different scenarios: I) luminosity fraction $\epsilon_\gamma$ microquasar jet luminosity, II) produced by relativistic electrons up-scattering radiation field star in magnetic $B$. obtain $\epsilon_\gamma < 5.4\times 10^{-6}$ scenario I, which tightly constrains models suggest observable high-energy neutrino HMMQs. In case II, non-detection VHE yields strong field, challenges synchrotron as dominant mechanism between keV MeV.