98 research outputs found
The 2HWC HAWC Observatory Gamma Ray Catalog
We present the first catalog of TeV gamma-ray sources realized with the
recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the
most sensitive wide field-of-view TeV telescope currently in operation, with a
1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an
instantaneous field of view >1.5 sr and >90% duty cycle, it continuously
surveys and monitors the sky for gamma ray energies between hundreds GeV and
tens of TeV.
HAWC is located in Mexico at a latitude of 19 degree North and was completed
in March 2015. Here, we present the 2HWC catalog, which is the result of the
first source search realized with the complete HAWC detector. Realized with 507
days of data and represents the most sensitive TeV survey to date for such a
large fraction of the sky. A total of 39 sources were detected, with an
expected contamination of 0.5 due to background fluctuation. Out of these
sources, 16 are more than one degree away from any previously reported TeV
source. The source list, including the position measurement, spectrum
measurement, and uncertainties, is reported. Seven of the detected sources may
be associated with pulsar wind nebulae, two with supernova remnants, two with
blazars, and the remaining 23 have no firm identification yet.Comment: Submitted 2017/02/09 to the Astrophysical Journa
The Sensitivity of HAWC to High-Mass Dark Matter Annihilations
The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view
detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in
central Mexico at 19 degrees North latitude and 4100 m above sea level, HAWC
will observe gamma rays and cosmic rays with an array of water Cherenkov
detectors. The full HAWC array is scheduled to be operational in Spring 2015.
In this paper, we study the HAWC sensitivity to the gamma-ray signatures of
high-mass (multi- TeV) dark matter annihilation. The HAWC observatory will be
sensitive to diverse searches for dark matter annihilation, including
annihilation from extended dark matter sources, the diffuse gamma-ray emission
from dark matter annihilation, and gamma-ray emission from non-luminous dark
matter subhalos. Here we consider the HAWC sensitivity to a subset of these
sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the
Galactic center. We simulate the HAWC response to gamma rays from these sources
in several well-motivated dark matter annihilation channels. If no gamma-ray
excess is observed, we show the limits HAWC can place on the dark matter
cross-section from these sources. In particular, in the case of dark matter
annihilation into gauge bosons, HAWC will be able to detect a narrow range of
dark matter masses to cross-sections below thermal. HAWC should also be
sensitive to non-thermal cross-sections for masses up to nearly 1000 TeV. The
constraints placed by HAWC on the dark matter cross-section from known sources
should be competitive with current limits in the mass range where HAWC has
similar sensitivity. HAWC can additionally explore higher dark matter masses
than are currently constrained.Comment: 15 pages, 4 figures, version to be published in PR
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
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
Horizontal muon track identification with neural networks in HAWC
Nowadays the implementation of artificial neural networks in high-energyphysics has obtained excellent results on improving signal detection. In thiswork we propose to use neural networks (NNs) for event discrimination in HAWC.This observatory is a water Cherenkov gamma-ray detector that in recent yearshas implemented algorithms to identify horizontal muon tracks. However, thesealgorithms are not very efficient. In this work we describe the implementationof three NNs: two based on image classification and one based on objectdetection. Using these algorithms we obtain an increase in the number ofidentified tracks. The results of this study could be used in the future toimprove the performance of the Earth-skimming technique for the indirectmeasurement of neutrinos with HAWC.<br
Combined dark matter searches towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS
Cosmological and astrophysical observations suggest that 85% of the total matter of the Universe is made of Dark Matter (DM). However, its nature remains one of the most challenging and fundamental open questions of particle physics. Assuming particle DM, this exotic form of matter cannot consist of Standard Model (SM) particles. Many models have been developed to attempt unraveling the nature of DM such as Weakly Interacting Massive Particles (WIMPs), the most favored particle candidates. WIMP annihilations and decay could produce SM particles which in turn hadronize and decay to give SM secondaries such as high energy \u1d6fe rays. In the framework of indirect DM search, observations of promising targets are used to search for signatures of DM annihilation. Among these, the dwarf spheroidal galaxies (dSphs) are commonly favored owing to their expected high DM content and negligible astrophysical background. In this work, we present the very first combination of 20 dSph observations, performed by the Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS collaborations in order to maximize the sensitivity of DM searches and improve the current results. We use a joint maximum likelihood approach combining each experiment’s individual analysis to derive more constraining upper limits on the WIMP DM self-annihilation cross-section as a function of DM particle mass. We present new DM constraints over the widest mass range ever reported, extending from 5 GeV to 100 TeV thanks to the combination of these five different \u1d6fe-ray instruments
Self-control interventions for children under age 10 for improving self-control and delinquency and problem behaviors
Self-control improvement programs are intended to serve many purposes, most
notably improving self-control. Yet, interventions such as these often aim to reduce
delinquency and problem behaviors. However, there is currently no summary
statement available regarding whether or not these programs are effective in
improving self-control and reducing delinquency and problem behaviors. The main objective of this review is to assess the available research evidence on the
effect of self-control improvement programs on self-control and delinquency and
problem behaviors. In addition to investigating the overall effect of early selfcontrol
improvement programs, this review will examine, to the extent possible, the
context in which these programs may be most successful. The studies included in this systematic review indicate that self-control
improvement programs are an effective intervention for improving self-control and
reducing delinquency and problem behaviors, and that the effect of these programs
appears to be rather robust across various weighting procedures, and across context,
outcome source, and based on both published and unpublished data
Nanotechnology advances towards development of targeted-treatment for obesity
Obesity through its association with type 2 diabetes (T2D), cancer and cardiovascular diseases (CVDs), poses a serious health threat, as these diseases contribute to high mortality rates. Pharmacotherapy alone or in combination with either lifestyle modifcation or surgery, is reliable in maintaining a healthy body weight, and preventing progression to obesity-induced diseases. However, the anti-obesity drugs are limited by non-specifcity and unsustainable weight loss efects. As such, novel and improved approaches for treatment of obesity are urgently needed. Nanotechnology-based therapies are investigated as an alternative strategy that can treat obesity and be able to overcome the
drawbacks associated with conventional therapies. The review presents three nanotechnology-based anti-obesity strategies that target the white adipose tissues (WATs) and its vasculature for the reversal of obesity. These include inhibition of angiogenesis in the WATs, transformation of WATs to brown adipose tissues (BATs), and photothermal lipolysis of WATs. Compared to conventional therapy, the targeted-nanosystems have high tolerability, reduced side efects, and enhanced efcacy. These efects are reproducible using various nanocarriers (liposomes, polymeric and gold nanoparticles), thus providing a proof of concept that targeted nanotherapy can be a feasible strategy that can combat obesity and prevent its comorbiditie
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