Search for High-Energy Gamma Rays in the Northern Fermi Bubble Region with the HAWC Observatory

Gamma-ray astronomy is the study of very energetic photons, from E = mec2 = 0.5x106 eV to \u3e 1020eV. Due to the large span of the energy range, the field focuses on non-thermal processes that include the acceleration and propagation of relativistic particles, which can be found in extreme environments such as pulsars, supernova remnants, molecular clouds, black holes, etc. The High Altitude Water Cherenkov (HAWC) observatory is an instrument designed for the study of gamma rays in the energy range of 100 GeV to 100 TeV. Using data from the HAWC observatory, a study for the search of very high energy gamma rays in the northern Fermi Bubble region was made. The Fermi Bubbles are large extended regions in the gamma-ray sky located above and below the galactic plane that present a hard emission between 1 GeV and 100 GeV. No significant excess is found an upper bounds at 95% C.L. are obtained. The implications of this result are that certain processes explaining the Fermi Bubble formation from the center of our galaxy are excluded. I will discuss and compare the scenarios that still present a possible hypothesis of the Fermi Bubble origin

Gamma Emission from Large Galactic Structures

Gamma-ray emission from large structures is useful for tracing the propagation and distribution of cosmic rays throughout our Galaxy. For example, the search for gamma-ray emission from Giant Molecular Clouds may allow us to probe the flux of cosmic rays in distant galactic regions and to compare it with the flux measured at Earth. Also, the composition of the cosmic rays can be measured by separating the gamma-ray emission from hadronic or leptonic processes. In the case of emission from the Fermi Bubbles specifically, constraining the mechanism of gamma-ray production can point to their origin. HAWC possesses a large field of view and good sensitivity to spatially extended sources, which currently makes it the best suited ground-based observatory to detect extended regions. We will present preliminary results on the search of gamma-ray emission from Molecular Clouds, as well as upper limits on the differential flux from the Fermi Bubbles.Comment: Presented at the 35th International Cosmic Ray Conference (ICRC2017), Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contribution

Search for Gamma-Ray and neutrino coincidences using HAWC and ANTARES data

In the quest for high-energy neutrino sources, the Astrophysical Multimessenger Observatory Network (AMON) has implemented a new search by combining data from the High Altitude Water Cherenkov (HAWC) observatory and the Astronomy with a Neutrino Telescope and Abyss environmental RESearch (ANTARES) neutrino telescope. Using the same analysis strategy as in a previous detector combination of HAWC and IceCube data, we perform a search for coincidences in HAWC and ANTARES events that are below the threshold for sending public alerts in each individual detector. Data were collected between July 2015 and February 2020 with a livetime of 4.39 years. Over this time period, 3 coincident events with an estimated false-alarm rate of <1 coincidence per year were found. This number is consistent with background expectations.Peer ReviewedPostprint (published version

Search for High-Energy Gamma Rays in the Northern Fermi Bubble Region with the HAWC Observatory

Gamma-ray astronomy is the study of very energetic photons, from E = mec2 ≈0.5×10 6 eV to > ≥1020eV. Due to the large span of the energy range, the field focuses on non-thermal processes that include the acceleration and propagation of relativistic particles, which can be found in extreme environments such as pulsars, supernova remnants, molecular clouds, black holes, etc. The High Altitude Water Cherenkov (HAWC) observatory is an instrument designed for the study of gamma rays in the energy range of ∼100 GeV to 100 TeV. Using data from the HAWC observatory, a study for the search of very high energy gamma rays in the northern Fermi Bubble region was made. The Fermi Bubbles are large extended regions in the gamma-ray sky located above and below the galactic plane that present a hard emission between 1 GeV and 100 GeV. No significant excess is found an upper bounds at 95% C.L. are obtained. The implications of this result are that certain processes explaining the Fermi Bubble formation from the center of our galaxy are excluded. I will discuss and compare the scenarios that still present a possible hypothesis of the Fermi Bubble origin

AMON Multimessenger Alerts: Past and Future

The Astrophysical Multimessenger Observatory Network (AMON) was founded to tie the world&rsquo;s high-energy and multimessenger observatories into a single network, with the purpose to enable the discovering of multimessenger sources, to exploit these sources for purposes of astrophysics, fundamental physics, and cosmology, and to explore archival datasets for evidence of multimessenger source populations. Contributions of AMON to date include the GCN prompt alerts for likely-cosmic neutrinos, multiple follow-up campaigns for likely-cosmic neutrinos including the IceCube-170922A event, and several archival searches for transient and flaring &gamma; + &nu; and &nu; + CR multimessenger sources. Given the new dawn of multimessenger astronomy recently realized with the detection of the neutron binary star merger and the possible &gamma; + &nu; coincidence detection from the blazar TXS0506+056, in 2019, we are planning to commission several multimessenger alert streams, including GW + &gamma; and high-energy &gamma; + &nu; coincidence alerts. We will briefly summarize the current status of AMON and review our monitoring plans for high-energy and multimessenger AMON alerts during what promises to be a very exciting year for multimessenger astrophysics

High-altitude characterization of the Hunga pressure wave with cosmic rays by the HAWC observatory

High-energy cosmic rays that hit the Earth can be used to study large-scale atmospheric perturbations. After a first interaction in the upper parts of the atmosphere, cosmic rays produce a shower of particles that sample it down to the detector level. The HAWC (High-Altitude Water Cherenkov) gamma-ray observatory in Central Mexico at 4,100 m elevation detects air shower particles continuously with 300 water Cherenkov detectors with an active area of 12,500 m2. On January 15th, 2022, HAWC detected the passage of the pressure wave created by the explosion of the Hunga volcano in the Tonga islands, 9,000 km away, as an anomaly in the measured rate of shower particles. The HAWC measurements are used to determine the propagation speed of four pressure wave passages, and correlate the variations of the shower particle rates with the barometric pressure changes. The profile of the shower particle rate and atmospheric pressure variations for the first transit of the pressure wave at HAWC is compared to the pressure measurements at the Tonga island, near the volcanic explosion. By using the cosmic-ray propagation in the atmosphere as a probe for the pressure, it is possible to achieve very high time-resolution measurements. Moreover, the high-altitude data from HAWC allows to observe the shape of the pressure anomaly with less perturbations compared to sea level detectors. Given the particular location and the detection method of HAWC, our high-altitude data provides valuable information that contributes to fully characterize this once-in-a-century phenomenon

Multimessenger gamma-ray and neutrino coincidence alerts using hawc and icecube subthreshold data

The High Altitude Water Cerenkov (HAWC) and IceCube observatories, through the Astrophysical Multimessenger Observatory Network (AMON) framework, have developed a multimessenger joint search for extragalactic astrophysical sources. This analysis looks for sources that emit both cosmic neutrinos and gamma rays that are produced in photohadronic or hadronic interactions. The AMON system is running continuously, receiving subthreshold data (i.e. data that are not suited on their own to do astrophysical searches) from HAWC and IceCube, and combining them in real time. Here we present the analysis algorithm, as well as results from archival data collected between 2015 June and 2018 August, with a total live time of 3.0 yr. During this period we found two coincident events that have a false-alarm rate (FAR) of <1 coincidence yr-1, consistent with the background expectations. The real-time implementation of the analysis in the AMON system began on 2019 November 20 and issues alerts to the community through the Gamma-ray Coordinates Network with an FAR threshold of <4 coincidences yr-1.SCOPUS: ar.jinfo:eu-repo/semantics/publishe