The HAWC
(High Altitude Water Cherenkov)
Observatory
The HAWC Collaboration
University of Maryland: Jordan Goodman, Andrew Smith,
Greg Sullivan, Jim Braun, David Berley
Los Alamos National Laboratory: Gus Sinnis, Brenda
Dingus, John Pretz
University of Wisconsin: Teresa Montaruli,
Stefan Westerhoff, Segev Ben Zvi, Juanan Aguilar, Dan
Wahl
University of Utah: Dave Kieda, Wayne Springer
Univ. of California, Irvine: Gaurang Yodh’
Michigan State University: Jim Linnemann,
Kirsten Tollefson, Dan Edmunds
George Mason University: Robert Ellsworth
Colorado State University: Miguel Mustafa, Dave Warner
University of New Hampshire: James Ryan
Pennsylvania State University: Tyce DeYoung,
Patrick Toale, Kathryne Sparks
University of New Mexico: John Matthews, William Miller
Michigan Technical University: Petra Hüntemeyer
NASA/Goddard Space Flight Center: Julie McEnery,
Elizabeth Hays, Vlasios Vasileiou
Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE): Alberto
Carramiñana, Eduardo Mendoza, Luis Carrasco,
William Wall, Daniel Rosa, Guillermo Tenorio Tagle, Sergey Silich
Universidad Nacional Autónoma de México (UNAM): Instituto de
Astronomía: Octavio Valenzuela, V ladimir Avila-Reese, Marco
Martos, Maria Magdalena Gonzalez, Sergio Mendoza, Dany Page,
William Lee, Hector Hernández, Deborah Dultzin, Erika Benitez
Instituto de Física: Arturo Menchaca, Rubén Alfaro, Varlen Grabski,
Andres Sandoval, Ernesto Belmont. Arnulfo Matinez-Davalos
Instituto de Ciencias Nucleares: Lukas Nellen, Gustavo MedinaTanco, Juan Carlos D’Olivo Instituto de Geofísica: José Valdés
Galicia, Alejandro Lara, Rogelio Caballero
Benemérita Universidad Autónoma de Puebla:Humberto Salazar,
Arturo Fernández, Caupatitzio Ramirez, Oscar Martínez, Eduardo
Moreno, Lorenzo Diaz, Alfonso Rosado,
Universidad Autónoma de Chiapas: Cesar Álvarez,
Eli Santos Rodriguez, Omar Pedraza
Universidad de Guadalajara: Eduardo de la Fuente
Universidad Michoacana de San Nicolás de Hidalgo: Luis Villaseñor,
Umberto Cotti, Ibrahim Torres, Juan Carlos Arteaga Velazquez
Centrode Investigacion y de Estudios Avanzados: Arnulfo Zepeda
Universidad de Guanajuato: David Delepine, Gerardo Moreno, Edgar
Casimiro Linares, Marco Reyes, Luis Ureña, Mauro Napsuciale, Victor
Migenes
Georgia Institute of Technology: Ignacio Taboada, Andreas
Tepe
HAWC Technical Staff: Michael Scheinder, Scott Delay
USA
Mexico
The HAWC Collaboration
University of Maryland: Jordan Goodman, Andrew Smith,
Greg Sullivan, Jim Braun, David Berley
Los Alamos National Laboratory: Gus Sinnis, Brenda
Dingus, John Pretz
University of Wisconsin: Teresa Montaruli,
Stefan Westerhoff, Dan Wahl
University of Utah: Dave Kieda, Wayne Springer
Univ. of California, Irvine: Gaurang Yodh
Michigan State University: Jim Linnemann,
Kirsten Tollefson, Dan Edmunds
George Mason University: Robert Ellsworth
University of New Hampshire: James Ryan
Pennsylvania State University: Tyce DeYoung,
Patrick Toale, Kathryne Sparks
University of New Mexico: John Matthews, William Miller
Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE): Alberto
Carramiñana, Eduardo Mendoza, Luis Carrasco,
William Wall, Daniel Rosa, Guillermo Tenorio Tagle, Sergey Silich
Universidad Nacional Autónoma de México (UNAM): Instituto de
Astronomía: Octavio Valenzuela, V ladimir Avila-Reese, Marco
Martos, Maria Magdalena Gonzalez, Sergio Mendoza, Dany Page,
William Lee, Hector Hernández, Deborah Dultzin, Erika Benitez
Instituto de Física: Arturo Menchaca, Rubén Alfaro, Varlen Grabski,
Andres Sandoval, Ernesto Belmont. Arnulfo Matinez-Davalos
Instituto de Ciencias Nucleares: Lukas Nellen, Gustavo MedinaTanco, Juan Carlos D’Olivo Instituto de Geofísica: José Valdés
Galicia, Alejandro Lara, Rogelio Caballero
Benemérita Universidad Autónoma de Puebla:Humberto Salazar,
Arturo Fernández, Caupatitzio Ramirez, Oscar Martínez, Eduardo
Moreno, Lorenzo Diaz, Alfonso Rosado,
Universidad Autónoma de Chiapas: Cesar Álvarez,
Eli Santos Rodriguez, Omar Pedraza
Universidad de Guadalajara: Eduardo de la Fuente
Michigan Technical University: Petra Hüntemeyer
Universidad Michoacana de San Nicolás de Hidalgo: Luis Villaseñor,
Umberto Cotti, Ibrahim Torres, Juan Carlos Arteaga Velazquez
NASA/Goddard Space Flight Center: Julie McEnery,
Elizabeth Hays, Vlasios Vasileiou
Centrode Investigacion y de Estudios Avanzados: Arnulfo Zepeda
Georgia Institute of Technology: Ignacio Taboada,
Andreas Tepe
Universidad de Guanajuato: David Delepine, Gerardo Moreno, Edgar
Casimiro Linares, Marco Reyes, Luis Ureña, Mauro Napsuciale, Victor
Migenes
HAWC Technical Staff: Michael Scheinder, Scott Delay
USA
Mexico
HAWC Science Objectives
• Discover the origin of cosmic rays by measuring gammaray spectra to 100 TeV
– Hadronic sources have unbroken spectra beyond 30-100 TeV
– Galactic diffuse gamma rays probe the distant cosmic ray flux
• Understand particle acceleration in astrophysical jets with
wide field of view, high duty factor observations.
– Trigger Multi-Messenger/Multi-Wavelength Observations of Flaring Active
Galactic Nuclei (including TeV orphan flares)
– Detect Short and Long Gamma-Ray Bursts
• Explore new physics via HAWC’s unbiased survey of ½ the
sky.
– Increase understanding of TeV sources to search for new physics.
– Study the local TeV cosmic rays and their anisotropy.
HAWC Collaboration
April 2010
HAWC Science
• Gamma Astronomy with wide FoV and high duty cycle:
– Understand particle acceleration in AGN and GRB jets through the
discovery of short and long GRBs at > 100 GeV energies and
• MWL Target of Opportunity programs on flares;
– Understand the sources of Galactic CRs through the observation of
galactic sources including extended ones (SNRs in molecular clouds,
superbubbles)
• Studies on EBL and diffuse gamma emissions.
• Hadronic Astronomy:
– find evidence of proton acceleration in Galactic CR sources (eg
understanding Milagro regions with larger statistics)
• Exotic phenomena
– photon oscillations in axion-like particles through EBL studies;
– Lorentz invariance;
– Slow Monopoles and Q-balls.
Comparison of Gamma-Ray
Detectors
Low Energy Threshold
EGRET/Fermi
Space-based (Small Area)
“Background Free”
Large Duty Cycle/Large Aperture
Sky Survey (< 10 GeV)
AGN Physics
Transients (GRBs) < 300 GeV
High Sensitivity
HESS, MAGIC, VERITAS
Large Effective Area
Excellent Background Rejection
Low Duty Cycle/Small Aperture
High Resolution Energy Spectra
up to ~20 TeV
Studies of known sources
Surveys of limited regions of sky
Large Aperture/High Duty Cycle
Milagro, Tibet, ARGO, HAWC
Moderate Area
Excellent Background Rejection
Large Duty Cycle/Large Aperture
Unbiased Sky Survey
Extended sources
Transients (GRB’s) > 100 GeV
High Energies up to 100 TeV
Intro
Milagro and HAWC
• Milagro was a first generation wide-field gamma-ray telescope:
– Proposed in 1990
– Operations began in 2001/04
– Developed g/h separation
• Discovered:
• more than a dozen TeV sources
• diffuse TeV emission from the Galactic plane
• a surprising directional excess of cosmic rays
• Showed that most bright galactic GeV sources extend to the TeV
• Best instrument for hard spectrum and extended sources
• HAWC is the next logical step
– It will be 15x more sensitive than Milagro
– It can be running in 3 yrs (with Fermi)
HAWC Collaboration
April 2010
HAWC Science Reviews
• PASAG - October 2009
– HAWC is a moderate-priced initiative that will
carry out excellent astrophysics using a novel
technique; there is also the possibility of
surprising results of relevance for particle
physics.
• NSF Review Panel December 2007:
– “There is a strong case for HAWC as a wide
field of view survey instrument at the TeV
scale.” They concluded the project is well
understood and technically ready with a strong
collaboration.
Milagro Results
15 TeV
associations out
of 35 likely
galactic sources
in our field of view
Abdo et al. ApJL (accepted)
arXiv:0904.1018
GeV Pulsars Produce TeV PWN
GeV Emission is pulsed & due to rotation axis
misaligned with Magnetic Dipole of ~1012 G
TeV Emission is produced by particles
further accelerated in the shock interacting
with the ambient medium.
IMPLICATIONS
• TeV PWN are prevalent with GeV pulsars
• GeV emission has broad beam
Geminga (J0634.0+1745)
10 parsecs
68% PSF
Milagro
HAWC
• Brightest GeV source
of 34 searched is
Geminga
• Old (300 kyr) PWN
and nearby (250 pc)
• ~10 parsec extent is
similar to HESS
observations of more
distant PWN
Milagro sees Geminga at 30% of the Crab at ~20 TeV
while IACTs have a limit of ~1% of the Crab at >200
GeV
Geminga with HAWC
10 parsecs
68% PSF
Milagro
HAWC
• Brightest GeV source
of 34 searched is
Geminga
• Old (300 kyr) PWN
and nearby (250 pc)
• ~10 parsec extent is
similar to HESS
observations of more
distant PWN
Milagro sees Geminga at 30% of the Crab at ~20 TeV
while IACTs have a limit of ~1% of the Crab at >200
GeV
Milagro Results
Milagro Spectrum of the Crab
Milagro
68%
HAWC
Energy reach from ~3TeV
to >100 TeV
Peak sensitivity for E-2
source at ~100 TeV
HESS Crab data/fit
Milagro Spectrum of the Crab w/HAWC
Milagro
68%
HAWC
Energy reach from ~3TeV
to >100 TeV
Peak sensitivity for E-2
source at ~100 TeV
HEGRA Crab data/fit
Milagro Results
MGRO J2019+37/ 0FGL J2020.8+3649
In Milagro J2019+37 is 700 mCrab
The flux in γ/s >200 GeV is 95mCrab
Milagro
68%
HAWC
HESS Crab fit:
(Io =3.76x10-7,Γ=2.39,
Ec=14.1 TeV)
This source is almost as bright as the
Crab at Milagro’s energy
MGRO J2019+37/ 0FGL J2020.8+3649
In Milagro J2019+37 is 700 mCrab
The flux in γ/s >200 GeV is 95mCrab
Milagro
68%
HAWC
HESS Crab fit:
(Io =3.76x10-7,Γ=2.39,
Ec=14.1 TeV)
Milagro Results
MGRO J1908+06
Milagro
68%
HAWC
Ecut 14
40 (156 (2
A Milagro discovered source now seen by HESS and VERITAS
Using HESS spectrum of -2.1 as input, Milagro requires a cut-off at <40(56) TeV
(N.B. Milagro measures a larger flux, possibly because we are integrating over a larger area than HESS)
HAWC Simulation
Milagro 3 source detected at 20 HAWC (3months)
HAWC Simulation
Milagro 3 source detected at 20 HAWC (3months)
HAWC Simulation
Milagro 3 source detected at 20 HAWC (3months)
Milagro Results
Diffuse TeV Excess
• Whether or not there is a GeV excess, Milagro sees a TeV excess.
• This excess could be due to unresolved sources or hadronic cosmic
rays hitting matter near their source.
• If the TeV excess has a flat spectrum, it is likely hadronic in origin and
may not be detectable at GeV energies.
– With help from ACTs and Fermi we will do a source subtraction
– This will allow us to measure the
spectrum and morphology of
the excess
• This study could point to regions
of the galaxy with a higher
concentration of cosmic rays
than near earth - pointing to
sites of acceleration.
Abdo et. al ApJ 2008
Active Galactic Nuclei Flares
Milagro’s 9 Mrk421
Milagro flux
• HAWC makes daily observations without weather, moon, or solar constraints.
• HAWC’s 5  sensitivity for Mrk 421 is (10,1,0.1) Crab in (3 min, 5 hrs, 1/3 yr)
• HAWC will notify multiwavelength observers in real time of flaring AGN
• Study correlations with x-rays, etc to determine emission mechanisms
• Discovery potential for orphan TeV flares producing neutrinos and UHECR
Quadratic or Linear?
Synchrotron Self
Compton or External
Compton?
1 month
Crab Flux
X-ray flux
Distinguishing New Physics from Astrophysics
• Violation of Lorentz Invariance OR Energy
Dependent Particle Acceleration
– HAWC will detect multiple flaring extragalactic sources (AGN and
GRBs) to resolve redshift vs source mechanisms
• Cosmological Star Formation OR Spectral Cutoffs in the source
– HAWC will trigger multiwavelength observations of flaring AGN to
obtain best measured and modeled TeV spectra
• Continuum Gamma-Ray Emission from Dark
Matter Annihilation OR Astrophysical Source
– HAWC will search for time variability which would imply an
astrophysical source
Milagro Results
Cosmic Ray Observations
Significance (σ’s)
Geminga
Heliotail
• Milagro data show an unexpected anisotropy (PRL 101, 221101, 2008)
• No weighting or cutting.
• Map dominated by charged cosmic rays.
• 10o smoothing, looking for intermediate sized features.
• Two regions of excess 15.0 and 12.7. Fractional excess of 6x10-4
(4x10-4) for region A(B).
Milagro Results
http://people.roma2.infn.it/~aldo/RICAP09_trasp_Web/Vernetto_ARGO_RICAP09ar.pdf
21
Milagro Results
Cosmic Ray Anisotropy
• Data are not consistent with:
– Mostly gamma-rays –> data looks hadronic
– with cosmic ray spectrum –> flatter, with ~10 TeV
cutoff
• HAWC with better energy resolution and gammahadron rejection can:
– Measure the spectrum with much higher precision
– Measure the gamma-ray fraction
• Understanding this is important for Dark Matter
Searches
HAWC Collaboration
April 2010
Geminga as a Local Cosmic Ray Source
• “If the observed cosmic ray excess does indeed arise from the
Geminga SN explosion, the long–sought “smoking gun” connecting
cosmic rays with supernovae would finally be at hand. - Salvati and
Sacco (AA 09)
• The confirmed presence of a nearby, ancient source of high-energy
electrons and positrons immediately suggests an explanation for the
positron excess.
-Yüksel, Kistler, Stanev
arXiv:0810.2784
PAMELA’s positron excess
Fit well given Milagro’s flux
from Geminga
HAWC Collaboration
April 2010