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Author HAWC Collaboration (Albert, A. et al); Salesa Greus, F. url  doi
openurl 
  Title Evidence that Ultra-high-energy Gamma Rays Are a Universal Feature near Powerful Pulsars Type Journal Article
  Year 2021 Publication Astrophysical Journal Letters Abbreviated Journal Astrophys. J. Lett.  
  Volume 911 Issue 2 Pages L27 - 8pp  
  Keywords  
  Abstract The highest-energy known gamma-ray sources are all located within 0.degrees 5 of extremely powerful pulsars. This raises the question of whether ultra-high-energy (UHE; >56 TeV) gamma-ray emission is a universal feature expected near pulsars with a high spin-down power. Using four years of data from the High Altitude Water Cherenkov Gamma-Ray Observatory, we present a joint-likelihood analysis of 10 extremely powerful pulsars to search for subthreshold UHE gamma-ray emission correlated with these locations. We report a significant detection (>3 sigma), indicating that UHE gamma-ray emission is a generic feature of powerful pulsars. We discuss the emission mechanisms of the gamma rays and the implications of this result. The individual environment, such as the magnetic field and particle density in the surrounding area, appears to play a role in the amount of emission.  
  Address [Albert, A.; Dingus, B. L.; Durocher, M.; Harding, J. P.; Malone, K.] Los Alamos Natl Lab, Phys Div, Los Alamos, NM 87545 USA, Email: kmalone@lanl.gov  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language (up) English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2041-8205 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000642352500001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4796  
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Author HAWC Collaboration (Albert, A. et al); Salesa Greus, F. url  doi
openurl 
  Title HAWC Search for High-mass Microquasars Type Journal Article
  Year 2021 Publication Astrophysical Journal Letters Abbreviated Journal Astrophys. J. Lett.  
  Volume 912 Issue 1 Pages L4 - 12pp  
  Keywords  
  Abstract 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 are poorly known. Using the High Altitude Water Cerenkov (HAWC) observatory, we search for excess gamma-ray emission coincident with the positions of known high-mass microquasars (HMMQs). No significant emission is observed for LS 5039, Cyg X-1, Cyg X-3, and SS 433 with 1523 days of HAWC data. We set the most stringent limit above 10 TeV obtained to date on each individual source. Under the assumption that HMMQs produce gamma rays via a common mechanism, we have performed source-stacking searches, considering two different scenarios: (I) gamma-ray luminosity is a fraction epsilon ( gamma ) of the microquasar jet luminosity, and (II) VHE gamma rays are produced by relativistic electrons upscattering the radiation field of the companion star in a magnetic field B. We obtain epsilon ( gamma ) < 5.4 x 10(-6) for scenario I, which tightly constrains models that suggest observable high-energy neutrino emission by HMMQs. In the case of scenario II, the nondetection of VHE gamma rays yields a strong magnetic field, which challenges synchrotron radiation as the dominant mechanism of the microquasar emission between 10 keV and 10 MeV.  
  Address [Albert, A.; Dingus, B. L.; Durocher, M.; Harding, J. P.; Malone, K.] Los Alamos Natl Lab, Div Phys, Los Alamos, NM 87545 USA, Email: kefang@physics.wisc.edu;  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language (up) English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2041-8205 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000646368700001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4798  
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