The TeV
Sky with
HAWC
Brenda Dingus
US Spokesperson
Los Alamos
National Lab
dingus@lanl.gov
8 August 2014
1 July 2014
Gamma-Ray Detectors
HAWC is a wide field of view (~2 sr), continuously operating
(>90% duty cycle), TeV observatory.
 Unbiased search for transients to initiate multi messenger
observations
 Highest energy observations with ~100 km2 hr exposure after 5 years
operation on > ½ the sky
Wide Field of View,
Continuous Operations TeV Sensitivity
Fermi
AGILE
EGRET
HAWC
ARGO
Milagro
VERITAS
HESS
MAGIC
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HAWC Design builds on Milagro
Milagro “1st Generation” Water Cherenkov
gamma-ray detector
• 2650m (8600’) elevation near Los Alamos, NM
• Covered pond of 4000 m2
• Operated 2000-2008
• Detected new Galactic sources, Galactic plane,
cosmic ray anisotropy, and put upper limits on
prompt emission from gamma-ray bursts
HAWC “2nd Generation” Water Cherenkov
gamma-ray detector
• 4100m (13500’) elevation near Puebla, Mexico
• 300 water tanks spread over 25000 m2
• Construction 2010-14, Operation 2013-19
• 15 x Milagro’s sensitivity with 10 x lower
energy threshold
©Aurore Simonnet
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HAWC Design
300 close packed water tanks (7.3m dia x 4.5 m deep of 200,000
liters) each with 4 upward facing photomultiplier tubes at the bottom
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HAWC Site Location in Mexico
• High Altitude Site of 4100 m with
temperate climate and existing
infrastructure
• 17 R.L. of atmospheric overburden
vs 27 R.L. at sea level
• Latitude of 19 deg N
HAWC
Large Millimeter
Telescope
(50m dia. dish)
Pico de Orizaba
5600 m
(18,500’)
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The HAWC Collaboration
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Los Alamos National Laboratory
Univ. of Maryland
Michigan State Univ.
University of Wisconsin
Pennsylvania State Univ.
Univ, of Utah
Univ. California Irvine
George Mason University
University of New Hampshire
University of New Mexico
Michigan Technological University
NASA/Goddard Space Flight Center
Georgia Institute of Technology
University of Alabama
Colorado State Univ.
Univ. California Santa Cruz
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Instituto Nacional de Astrofísica Óptica y Electrónica
Universidad Nacional Autónoma de México
• Instituto de Física
• Instituto de Astronomía
• Instituto de Geofisica
• Instituto de Ciencias Nucleares
Benemérita Universidad Autónoma de Peubla
Universidad Autónoma de Chiapas
Universidad Autónoma del Estado de Hidalgo
Universidad de Guadalajara
Universidad Michoacana de San Nicolás de Hidalgo
Centro de Investigacion y de Estudios Avanzados
Universidad de Guanajuato
~100 Members
Mexico
USA
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11/2010
13M USD project
funding began
Feb 2011
Operations with 111
water Cherenkov
detectors began
Aug 2013
Currently, 264
water tanks have
been built.
Construction will be
complete by end
of 2014
02/2012
08/2012
05/2013
01/2014
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Construction
Progressing
Well
Steel
Survey
Water
PMTs
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HAWC-30 Completed Sept 2012
HAWC 30 Events and
Observation of cosmic-ray
shadow of Moon with 70 days of
data
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HAWC-95/111 Skymap
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HAWC-95/111 Skymap
Crab Nebula
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HAWC-95/111 Skymap
Mrk 501 Blazar
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HAWC-95/111 Skymap
Mrk 421 Blazar
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HAWC Differential Sensitivity
Differential Sensitivity per Quarter Decade of Energy
http://arxiv.org/abs/1306.5800 Astroparticle Physics 2013
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HAWC Integral Sensitivity
vs. Declination
vs. High Energy Cut off
http://arxiv.org/abs/1306.5800 Astroparticle Physics 2013
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HAWC’s Field Of View
KnownTeV sources are shown, but most of the high
latitude sky has not been observed at TeV energies
Sources from TeVCAT.uchicago.edu
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Highest Energy Sources
For example, MGRO J2019+37 SED peaks >10 TeV.
Aliu, et al. 2014, “Spatially resolving MGR0 2019+37 with VERITAS
HAWC will likely discover new higher
energy peaked sources.
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Cygnus: A Complicated Region
• MGRO J2031+41:
- Collocated extended emission
detected by IACTs, Milagro, and
ARGO
- Spectrum appears to line up with the
Fermi cocoon cosmic ray
acceleration model can explain the
diffuse emission in the cocoon
© M. Hui
Milagro contours on
Fermi counts map
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HAWC: Extended Sources
Milagro’s Detection of an extended
excess coincident with Geminga
PAMELA’s positron excess is well fit
given Milagro’s flux from Geminga
~ 10 parsec
Yüksel, Kistler, Stanev PRL 2009
HAWC will detect Geminga with >50s to measure spectra and map
diffusion near source.
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HAWC: Active Galactic Nuclei Flares
~50 known TeV AGN
• IACT observations have <1% duty cycle/AGN & detect no flaring in many
HAWC’s will monitor all Northern AGN with 20% duty cycle/day (5 hrs)
regardless of sun, moon, or weather
HAWC’s 5 s sensitivity is (10,1,0.1) Crab in (3 min, 5 hrs, 1/3 yr)
Worldwide Dataset of TeV Observations by IACTs of Mrk421
1 month
3 minutes
5 hours
Tluczykont et al. 2010
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HAWC: Distant Sources
• TeV g-rays are attenuated by pair production
• TeV spectra from distant sources probe:
• Cosmology of
Extragalactic Background Light
• Sources of UHECRs
• Intergalactic Magnetic Field in Voids
Essey, Kalashev, Kusenko, Beacom, PRL 2010
• Axion Like Particles
g  a  g (Hooper & Serpico, PRL 2007)
HAWC will survey sky for new TeV AGN,
measure multi-TeV spectra and variability,
and enable multimessenger observations
through prompt notification of flaring
activity.
TeV spectra extend beyond pair production
threshold for many sources (Horns&Meyer
2012)
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HAWC: Gamma-Ray Bursts
Fermi observation of
GRB090510, z=0.9
• Highest Observed Energy
was 33 GeV with
16 g-rays >1 GeV
• Constrained Lorentz
Invariance at the Plank Mass
scale
GRB130427: Fermi detected 94
GeV g-ray
HAWC would detect this GRB if
it occurred in FOV
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HAWC: GRB sensitivity
 GRB130427
z=0.34
z=0.91
Abeysekara et al., Astroparticle
Physics, 2011
• Fermi LAT sensitivity
assumes 1 gamma-ray > 10
GeV
• Scaler sensitivity uses sum
of single photoelectron
rates in individual PMTs to
observe shortest and most
distant transients
• Gilmore & Taboada, NIM A
2013 predict HAWC will
detect 1.6 GRBs/yr
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HAWC: Dark Matter
• HAWC has sensitivity to indirect detection of TeV WIMPs in satellite
galaxies, the Galactic Center, and galaxy clusters
• Cosmological simulations predict more satellite galaxies than
observed
• Higher M/L galaxies have been found by Sloan Deep Survey
• HAWC will observe all M/L galaxies in half the sky, even if L=0
• Solid lines are 5
sigma sensitivity.
• Dashed lines show
sensitivity with the
expected
Sommerfeld
enhancement due to
additional
resonances.
Preliminary
• Horizontal line is the
cross section for
thermal production of
WIMPs.
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HAWC: Cosmic Rays
Milagro Discovered an Anisotropy of 10 TeV Cosmic Rays (PRL, 2009)
• Confirmed in Northern Hemisphere by ARGO and now HAWC, and in Southern
Hemisphere by Ice Cube
• Gyroradius of 10TeV proton in 2mG field is 0.005 parsecs=1000 AU
• No known sources within this distance
• Heliospheric Effect?
• Annihilation in protons of nearby Dark Matter? (Harding, astroph/1307.6537)
• Strangelets (stable quark matter)? (Kotera, Perez-Garcia, Silk astroph/1303.1186v1)
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• Increase photodetection
efficiency for lower energies
• Winston Cones
• Large Area Photodetectors
• Liquid Scintillator
• Larger Area Array
• Sensitivity proportional to
Area, NOT sqrt(Area) due
to background rejection
E dN/dE
(arbitrary scale)
Beyond HAWC: Increase Sensitivity
HAWC Single
photoelectron threshold
Energy of Secondary Particles in Air
Shower at Ground Level (MeV)
Muons have broad lateral distribution
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Beyond HAWC: Southern Site
• Discovering rare transient events requires full sky coverage
• GRB finder for Advanced LIGO, which will detect all
neutron binary coalescence with z<0.5
• AGN flares & GRBs as distant probes of high energy
physics (e.g. Lorentz invariance and axions)
• Galactic Center
• TeV Source finder for CTA south
Alto Chorrillo
Argentina
4800m
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Beyond HAWC: Even Lower Energy
• Same detector at a
higher altitude has
increased sensitivity
especially at lower
energies
• Factor of 4 increase in
sensitivity between
ALMA and HAWC
altitude
Sensitivity for one year of
observation of an array of 900
tanks with 900 PMTs at
different altitudes
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HAWC is now!
• Construction complete in 2014
• Science operations with 111 tanks
began 1 Aug 2013
• First results are coming now
HAWC detects
Crab>10s
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BACKUP
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HAWC Performance
Much Better
Low Energy
Response
Much Better
Background
Rejection
(b)
(a)
HAWC
Milagro
Milagro
HAWC
Milagro
Milagro
HAWC
(c) Better
Energy
Resolution
HAWC
Much Better
Angular
(d)
Resolution
Gammas
8 TeV at ϴ=10°
838 Hit PMTs
21 TeV at ϴ=21°
1131 Hit PMTs
24 TeV at ϴ=44°
837 Hit PMTs
Protons
118 TeV at ϴ=52°
1116 Hit PMTs
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Brian Baughman - HAWC
Energy
deposited
Collaboration
- ICRC 2013 Rio away from core
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Extensive Air Shower Development
4100m
2600m
• Higher Altitude means fewer radiation lengths and more
particles (~5x) for same primary energy