Probing the Sea of Cosmic Rays by Measuring Gamma-Ray Emission from Passive Giant Molecular Clouds. (arXiv:2101.08748v1 [astro-ph.HE])

Probing the Sea of Cosmic Rays by Measuring Gamma-Ray Emission from Passive Giant Molecular Clouds. (arXiv:2101.08748v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Albert_A/0/1/0/all/0/1">A. Albert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alfaro_R/0/1/0/all/0/1">R. Alfaro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alvarez_C/0/1/0/all/0/1">C. Alvarez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Camacho_J/0/1/0/all/0/1">J.R. Angeles Camacho</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arteaga_Velazquez_J/0/1/0/all/0/1">J.C. Arteaga-Vel&#xe1;zquez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arunbabu_K/0/1/0/all/0/1">K.P. Arunbabu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rojas_D/0/1/0/all/0/1">D. Avila Rojas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Solares_H/0/1/0/all/0/1">H.A. Ayala Solares</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Baghmanyan_V/0/1/0/all/0/1">V. Baghmanyan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Belmont_Moreno_E/0/1/0/all/0/1">E. Belmont-Moreno</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+BenZvi_S/0/1/0/all/0/1">S.Y. BenZvi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brisbois_C/0/1/0/all/0/1">C. Brisbois</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Caballero_Mora_K/0/1/0/all/0/1">K.S. Caballero-Mora</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Capistran_T/0/1/0/all/0/1">T. Capistr&#xe1;n</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carraminana_A/0/1/0/all/0/1">A. Carrami&#xf1;ana</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Casanova_S/0/1/0/all/0/1">S. Casanova</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cotti_U/0/1/0/all/0/1">U. Cotti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cotzomi_J/0/1/0/all/0/1">J. Cotzomi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Leon_S/0/1/0/all/0/1">S. Couti&#xf1;o de Le&#xf3;n</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fuente_E/0/1/0/all/0/1">E. De la Fuente</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hernandez_R/0/1/0/all/0/1">R. Diaz Hernandez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dingus_B/0/1/0/all/0/1">B.L. Dingus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+DuVernois_M/0/1/0/all/0/1">M.A. DuVernois</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Durocher_M/0/1/0/all/0/1">M. Durocher</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Diaz_Velez_J/0/1/0/all/0/1">J.C. D&#xed;az-V&#xe9;lez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ellsworth_R/0/1/0/all/0/1">R.W. Ellsworth</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Engel_K/0/1/0/all/0/1">K. Engel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Espinoza_C/0/1/0/all/0/1">C. Espinoza</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fan_K/0/1/0/all/0/1">K.L. Fan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alonso_M/0/1/0/all/0/1">M. Fern&#xe1;ndez Alonso</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fraija_N/0/1/0/all/0/1">N. Fraija</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Galvan_Gamez_A/0/1/0/all/0/1">A. Galv&#xe1;n-G&#xe1;mez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garcia_D/0/1/0/all/0/1">D. Garcia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gonzalez_J/0/1/0/all/0/1">J.A. Garc&#xed;a-Gonz&#xe1;lez F. Garfias M.M. Gonz&#xe1;lez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goodman_J/0/1/0/all/0/1">J.A. Goodman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Harding_J/0/1/0/all/0/1">J.P. Harding</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hernandez_S/0/1/0/all/0/1">S. Hernandez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hona_B/0/1/0/all/0/1">B. Hona</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huang_D/0/1/0/all/0/1">D. Huang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hueyotl_Zahuantitla_F/0/1/0/all/0/1">F. Hueyotl-Zahuantitla</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+H%7Funtemeyer_P/0/1/0/all/0/1">P. H&#xfc;ntemeyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Iriarte_A/0/1/0/all/0/1">A. Iriarte</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Joshi_V/0/1/0/all/0/1">V. Joshi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kieda_D/0/1/0/all/0/1">D. Kieda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lara_A/0/1/0/all/0/1">A. Lara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_W/0/1/0/all/0/1">W.H. Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_J/0/1/0/all/0/1">J. Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vargas_H/0/1/0/all/0/1">H. Le&#xf3;n Vargas</a>, et al. (42 additional authors not shown)

The study of high-energy gamma rays from passive Giant Molecular Clouds
(GMCs) in our Galaxy is an indirect way to characterize and probe the paradigm
of the “sea” of cosmic rays in distant parts of the Galaxy. By using data from
the High Altitude Water Cherenkov (HAWC) observatory, we measure the gamma-ray
flux above 1 TeV of a set of these clouds to test the paradigm.

We selected high-galactic latitude clouds that are in HAWC’s field-of-view
and which are within 1~kpc distance from the Sun. We find no significant excess
emission in the cloud regions, nor when we perform a stacked log-likelihood
analysis of GMCs that are considered part of the Gould Belt. Using a Bayesian
approach, we calculate 95% credible interval upper limits together with the
sensitivity of HAWC. These are the first limits to constrain gamma-ray emission
in the multi-TeV energy range ($>$1 TeV). Assuming that the main gamma-ray
production mechanism is due to proton-proton interaction, the upper limits are
consistent with a cosmic-ray flux and energy density similar to that measured
at Earth.

The study of high-energy gamma rays from passive Giant Molecular Clouds
(GMCs) in our Galaxy is an indirect way to characterize and probe the paradigm
of the “sea” of cosmic rays in distant parts of the Galaxy. By using data from
the High Altitude Water Cherenkov (HAWC) observatory, we measure the gamma-ray
flux above 1 TeV of a set of these clouds to test the paradigm.

We selected high-galactic latitude clouds that are in HAWC’s field-of-view
and which are within 1~kpc distance from the Sun. We find no significant excess
emission in the cloud regions, nor when we perform a stacked log-likelihood
analysis of GMCs that are considered part of the Gould Belt. Using a Bayesian
approach, we calculate 95% credible interval upper limits together with the
sensitivity of HAWC. These are the first limits to constrain gamma-ray emission
in the multi-TeV energy range ($>$1 TeV). Assuming that the main gamma-ray
production mechanism is due to proton-proton interaction, the upper limits are
consistent with a cosmic-ray flux and energy density similar to that measured
at Earth.

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