140 research outputs found
Search for Decaying Dark Matter in the Virgo Cluster of Galaxies with HAWC
The decay or annihilation of dark matter particles may produce a steady flux
of very-high-energy gamma rays detectable above the diffuse background. Nearby
clusters of galaxies provide excellent targets to search for the signatures of
particle dark matter interactions. In particular, the Virgo cluster spans
several degrees across the sky and can be efficiently probed with a wide
field-of-view instrument. The High Altitude Water Cherenkov (HAWC) observatory,
due to its wide field of view and sensitivity to gamma rays at an energy scale
of 300 GeV--100 TeV is well-suited for this search. Using 2141 days of data, we
search for gamma-ray emission from the Virgo cluster, assuming well-motivated
dark matter sub-structure models. Our results provide some of the strongest
constraints on the decay lifetime of dark matter for masses above 10 TeV.Comment: 7 pages, 3 figures. Submitted to PR
HAWC Study of Very-High-Energy -ray Spectrum of HAWC J1844-034
Recently, the region surrounding eHWC J1842-035 has been studied extensively
by gamma-ray observatories due to its extended emission reaching up to a few
hundred TeV and potential as a hadronic accelerator. In this work, we use 1,910
days of cumulative data from the High Altitude Water Cherenkov (HAWC)
observatory to carry out a dedicated systematic source search of the eHWC
J1842-035 region. During the search we have found three sources in the region,
namely, HAWC J1844-034, HAWC J1843-032, and HAWC J1846-025. We have identified
HAWC J1844-034 as the extended source that emits photons with energies up to
175 TeV. We compute the spectrum for HAWC J1844-034 and by comparing with the
observational results from other experiments, we have identified HESS
J1843-033, LHAASO J1843-0338, and TASG J1844-038 as very-high-energy gamma-ray
sources with a matching origin. Also, we present and use the multi-wavelength
data to fit the hadronic and leptonic particle spectra. We have identified four
pulsar candidates in the nearby region from which PSR J1844-0346 is found to be
the most likely candidate due to its proximity to HAWC J1844-034 and the
computed energy budget. We have also found SNR G28.6-0.1 as a potential
counterpart source of HAWC J1844-034 for which both leptonic and hadronic
scenarios are feasible.Comment: 13 pages, 9 figures, published in Ap
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), 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 = , with TeV cm s and . 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
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 the
atmosphere down to the detector level. The HAWC (High-Altitude Water Cherenkov)
cosmic-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 m. 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 characterize the shape of four pressure wave
passages, determine the propagation speed of each one, and correlate the
variations of the shower particle rates with the barometric pressure changes,
extracting a barometric parameter. 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 Tonga island, near the
volcanic explosion. This work opens the possibility of using large particle
cosmic-ray air shower detectors to trace large atmospheric transient waves.Comment: Contact about this analysis: A. Sandoval ([email protected]),
A. Lara ([email protected]) & H. Le\'on Vargas
([email protected]
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 () for annihilation
cross-section and decay lifetime for WIMP candidates with masses between
and . 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 orders of magnitude weaker than
the ultrafaint dSph limits.Comment: 22 pages, 11 figures, 3 table
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 , 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
A Contribution of the HAWC Observatory to the TeV era in the High Energy Gamma-Ray Astrophysics: The case of the TeV-Halos
We present a short overview of the TeV-Halos objects as a discovery and a
relevant contribution of the High Altitude Water \v{C}erenkov (HAWC)
observatory to TeV astrophysics. We discuss history, discovery, knowledge, and
the next step through a new and more detailed analysis than the original study
in 2017. TeV-Halos will contribute to resolving the problem of the local
positron excess observed on the Earth. To clarify the latter, understanding the
diffusion process is mandatory.Comment: Work presented in the 21st International Symposium on Very High
Energy Cosmic Ray Interactions(ISVHECRI 2022) as part of the Ph. D. Thesis of
Ramiro Torres-Escobedo (SJTU, Shanghai, China). Accepted for publication in
SciPost Physics Proceedings (ISSN 2666-4003). 11 pages, 3 Figures. Short
overview of HAWC and TeV Halos objects until 202
HAWC and Fermi-LAT Detection of Extended Emission from the Unidentified Source 2HWC J2006+341
The discovery of the TeV point source 2HWC J2006+341 was reported in the
second HAWC gamma-ray catalog. We present a follow-up study of this source
here. The TeV emission is best described by an extended source with a soft
spectrum. At GeV energies, an extended source is significantly detected in
Fermi-LAT data. The matching locations, sizes and spectra suggest that both
gamma-ray detections correspond to the same source. Different scenarios for the
origin of the emission are considered and we rule out an association to the
pulsar PSR J2004+3429 due to extreme energetics required, if located at a
distance of 10.8 kpc.Comment: 12 pages, 2 figures. To appear in ApJ
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
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