A Quantitative Approach to the Watershed Governance Prism: The Duero River Basin, Mexico

Advances have been made in water resource investigation due to the implementation of mathematical models, the development of theoretical frameworks, and the evaluation of sustainability indices. Together, they improve and make integrated water resource management more efficient. In this paper, in the study area of the Duero River Basin, located in Michoacan, Mexico, we schematize a series of numerical indices of the Watershed Governance Prism to determine the quantitative status of water governance in a watershed. The results, presented as axes, perspectives, and prisms in the Axis Index, Water Governance Index, and Watershed Governance Prism Index, provide the conclusion that it is possible to establish and evaluate the Watershed Governance Prism Index using our numerical implementation of the Watershed Governance Prism theoretical framework. Thus, it is possible to define a quantitative status and evoke how water governance is being designed and implemented in a watershed

Study of the Very High Energy emission of M87 through its broadband spectral energy distribution

The radio galaxy M87 is the central dominant galaxy of the Virgo Cluster.Very High Energy (VHE,$\gtrsim 0.1$ TeV) emission, from M87 has been detectedby Imaging Air Cherenkov Telescopes (IACTs ). Recently, marginal evidence forVHE long-term emission has also been observed by the High Altitude WaterCherenkov (HAWC) Observatory, a gamma ray and cosmic-ray detector array locatedin Puebla, Mexico. The mechanism that produces VHE emission in M87 remainsunclear. This emission is originated in its prominent jet, which has beenspatially resolved from radio to X-rays. In this paper, we constructed aspectral energy distribution from radio to gamma rays that is representative ofthe non-flaring activity of the source, and in order to explain the observedemission, we fit it with a lepto-hadronic emission model. We found that thismodel is able to explain non-flaring VHE emission of M87 as well as an orphanflare reported in 2005.<br

Searching for TeV Dark Matter in Irregular dwarf galaxies with HAWC Observatory

We present the results of dark matter (DM) searches in a sample of 31 dwarf irregular (dIrr) galaxies within the field of view of the HAWC Observatory. dIrr galaxies are DM dominated objects, which astrophysical gamma-ray emission is estimated to be negligible with respect to the secondary gamma-ray flux expected by annihilation or decay of Weakly Interacting Massive Particles (WIMPs). While we do not see any statistically significant DM signal in dIrr galaxies, we present the exclusion limits ($95\%~\text{C.L.}$) for annihilation cross-section and decay lifetime for WIMP candidates with masses between $1$ and $100~\text{TeV}$. Exclusion limits from dIrr galaxies are relevant and complementary to benchmark dwarf Spheroidal (dSph) galaxies. In fact, dIrr galaxies are targets kinematically different from benchmark dSph, preserving the footprints of different evolution histories. We compare the limits from dIrr galaxies to those from ultrafaint and classical dSph galaxies previously observed with HAWC. We find that the contraints are comparable to the limits from classical dSph galaxies and $\thicksim2$ orders of magnitude weaker than the ultrafaint dSph limits.Comment: 22 pages, 11 figures, 3 table

Constraints on the very high energy gamma-ray emission from short GRBs with HAWC

Many gamma-ray bursts (GRBs) have been observed from radio wavelengths, and afew at very-high energies (VHEs, > 100GeV). The HAWC gamma-ray observatory iswell suited to study transient phenomena at VHEs due to its large field of viewand duty cycle. These features allow for searches of VHE emission and can probedifferent model assumptions of duration and spectra. In this paper, we use datacollected by HAWC between December 2014 and May 2020 to search for emission inthe energy range from 80 to 800 GeV coming from a sample 47 short GRBs thattriggered the Fermi, Swift and Konus satellites during this period. Thisanalysis is optimized to search for delayed and extended VHE emission withinthe first 20 s of each burst. We find no evidence of VHE emission, eithersimultaneous or delayed, with respect to the prompt emission. Upper limits (90%confidence level) derived on the GRB fluence are used to constrain thesynchrotron self-Compton forward-shock model. Constraints for the interstellardensity as low as $10^{-2}$ cm$^{-3}$ are obtained when assuming z=0.3 forbursts with the highest keV-fluences such as GRB 170206A and GRB 181222841.Such a low density makes observing VHE emission mainly from the fast coolingregime challenging.<br

Galactic Gamma-Ray Diffuse Emission at TeV energies with HAWC Data

The Galactic gamma-ray diffuse emission (GDE) is emitted by cosmic rays (CRs), ultra-relativistic protons and electrons, interacting with gas and electromagnetic radiation fields in the interstellar medium. Here we present the analysis of TeV diffuse emission from a region of the Galactic Plane over the range in longitude of $l\in[43^\circ,73^\circ]$, using data collected with the High Altitude Water Cherenkov (HAWC) detector. Spectral, longitudinal and latitudinal distributions of the TeV diffuse emission are shown. The radiation spectrum is compatible with the spectrum of the emission arising from a CR population with an "index" similar to that of the observed CRs. When comparing with the \texttt{DRAGON} \textit{base model}, the HAWC GDE flux is higher by about a factor of two. Unresolved sources such as pulsar wind nebulae and TeV halos could explain the excess emission. Finally, deviations of the Galactic CR flux from the locally measured CR flux may additionally explain the difference between the predicted and measured diffuse fluxes

The TeV Sun Rises: Discovery of Gamma rays from the Quiescent Sun with HAWC

We report the first detection of a TeV gamma-ray flux from the solar disk (6.3$\sigma$), based on 6.1 years of data from the High Altitude Water Cherenkov (HAWC) observatory. The 0.5--2.6 TeV spectrum is well fit by a power law, dN/dE = $A (E/1 \text{ TeV})^{-\gamma}$, with $A = (1.6 \pm 0.3) \times 10^{-12}$ TeV$^{-1}$ cm$^{-2}$ s$^{-1}$ and $\gamma = -3.62 \pm 0.14$. The flux shows a strong indication of anticorrelation with solar activity. These results extend the bright, hard GeV emission from the disk observed with Fermi-LAT, seemingly due to hadronic Galactic cosmic rays showering on nuclei in the solar atmosphere. However, current theoretical models are unable to explain the details of how solar magnetic fields shape these interactions. HAWC's TeV detection thus deepens the mysteries of the solar-disk emission.Comment: 15 pages, 8 figures including supplementary material. Accepted for publication in Physical Review Letter

Gamma/Hadron Separation with the HAWC Observatory

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory observesatmospheric showers produced by incident gamma rays and cosmic rays with energyfrom 300 GeV to more than 100 TeV. A crucial phase in analyzing gamma-raysources using ground-based gamma-ray detectors like HAWC is to identify theshowers produced by gamma rays or hadrons. The HAWC observatory records roughly25,000 events per second, with hadrons representing the vast majority($>99.9\%$) of these events. The standard gamma/hadron separation technique inHAWC uses a simple rectangular cut involving only two parameters. This workdescribes the implementation of more sophisticated gamma/hadron separationtechniques, via machine learning methods (boosted decision trees and neuralnetworks), and summarizes the resulting improvements in gamma/hadron separationobtained in HAWC.<br

Gamma-ray Emission from Classical Nova V392 Per: Measurements from Fermi and HAWC

This paper reports on the $\gamma$-ray properties of the 2018 Galactic novaV392 Per, spanning photon energies $\sim$0.1 GeV to 100 TeV by combiningobservations from the Fermi Gamma-ray Space Telescope and the HAWC Observatory.In one of the most rapidly evolving $\gamma$-ray signals yet observed for anova, GeV $\gamma$ rays with a power law spectrum with index $\Gamma = 2.0 \pm0.1$ were detected over eight days following V392 Per's optical maximum. HAWCobservations constrain the TeV $\gamma$-ray signal during this time and alsobefore and after. We observe no statistically significant evidence of TeV$\gamma$-ray emission from V392 Per, but present flux limits. Tests of theextension of the Fermi/LAT spectrum to energies above 5 TeV are disfavored by 2standard deviations (95\%) or more. We fit V392 Per's GeV $\gamma$ rays withhadronic acceleration models, incorporating optical observations, and comparethe calculations with HAWC limits.<br

Limits on the Diffuse Gamma-Ray Background above 10 TeV with HAWC

The high-energy Diffuse Gamma-Ray Background (DGRB) is expected to be produced by unresolved isotropically distributed astrophysical objects, potentially including dark matter annihilation or decay emissions in galactic or extragalactic structures. The DGRB has only been observed below 1 TeV; above this energy, upper limits have been reported. Observations or stringent limits on the DGRB above this energy could have significant multi-messenger implications, such as constraining the origin of TeV-PeV astrophysical neutrinos detected by IceCube. The High Altitude Water Cherenkov (HAWC) Observatory, located in central Mexico at 4100 m above sea level, is sensitive to gamma rays from a few hundred GeV to several hundred TeV and continuously observes a wide field-of-view (2 sr). With its high-energy reach and large area coverage, HAWC is well-suited to notably improve searches for the DGRB at TeV energies. In this work, strict cuts have been applied to the HAWC dataset to better isolate gamma-ray air showers from background hadronic showers. The sensitivity to the DGRB was then verified using 535 days of Crab data and Monte Carlo simulations, leading to new limits above 10 TeV on the DGRB as well as prospective implications for multi-messenger studies.Comment: 8 pages, 3 figure