  The HAWC Collaboration released the 2HWC catalog of TeV sources, in which 19
show no association with any known high-energy (HE; E > 10 GeV) or
very-high-energy (VHE; E > 300 GeV) sources. This catalog motivated follow-up
studies by both the MAGIC and Fermi-LAT observatories with the aim of
investigating gamma-ray emission over a broad energy band. In this paper, we
report the results from the first joint work between HAWC, MAGIC and Fermi-LAT
on three unassociated HAWC sources: 2HWC J2006+341, 2HWC J1907+084* and 2HWC
J1852+013*. Although no significant detection was found in the HE and VHE
regimes, this investigation shows that a minimum 1 degree extension (at 95%
confidence level) and harder spectrum in the GeV than the one extrapolated from
HAWC results are required in the case of 2HWC J1852+013*, while a simply
minimum extension of 0.16 degrees (at 95% confidence level) can already explain
the scenario proposed by HAWC for the remaining sources. Moreover, the
hypothesis that these sources are pulsar wind nebulae is also investigated in
detail.
