HAWC - A Wide-Field Gamma-Ray Telescope · Brenda Dingus 8 Nov 2007 Complementarity Complementarity of TeV Gamma-Ray Detectors Imaging Air Cherenkov Telescopes Extensive Air Shower

Brenda Dingus8 Nov 2007

HAWC HAWC (High Altitude Water Cherenkov)(High Altitude Water Cherenkov) A WideA Wide--Field GammaField Gamma--Ray TelescopeRay Telescope

Brenda DingusBrenda DingusLos Alamos National LabLos Alamos National Lab


ComplementarityComplementarity of TeV Gammaof TeV Gamma--Ray Detectors Ray Detectors Imaging Air Cherenkov Telescopes Extensive Air Shower Arrays

Energy RangeEnergy Range 0.050.05--50 TeV50 TeV 0.10.1--100100 TeVTeV

AreaArea >10>1044 mm22 >10>1044 mm22

Background RejectionBackground Rejection >99%>99% >95%>95%

Angular ResolutionAngular Resolution 0.050.05oo 0.30.3--0.70.7oo

Energy ResolutionEnergy Resolution ~15%~15% ~50%~50%

ApertureAperture 0.003 0.003 srsr 2 2 srsr

Duty CycleDuty Cycle 10%10% 95%95%

IACTs EAS arrays


HAWC Detector DesignHAWC Detector Design

From Milagro to HAWC:From Milagro to HAWC:•• Increase Altitude to 4100 m from Increase Altitude to 4100 m from

2650 m 2650 m •• Increase Area to 22,000 mIncrease Area to 22,000 m2 2 from from

4,000 m4,000 m2 2 (top layer) or 2,200m(top layer) or 2,200m2 2

(bottom layer)(bottom layer)•• Reuse 900 Milagro PMTs and Reuse 900 Milagro PMTs and

front end electronics front end electronics •• Cost $7.4MCost $7.4M•• HAWC 10 HAWC 10 –– 15 x Sensitivity of 15 x Sensitivity of

Milagro:Milagro:–– HAWC: HAWC: Detect Crab in ~ 1 day (5Detect Crab in ~ 1 day (5σσ))–– Milagro: Milagro: Detects Crab in 3 monthsDetects Crab in 3 months

e μ γ


HAWC Detector DesignHAWC Detector Design

• 900 water tanks• Tanks are 5 meter

diameter and 4.3 meter deep

• Tanks cost $4.1k each (inc. shipping)

• One 8” PMT/tank• Tank array covers

area of 150m x 150m with 78% coverage

DAQ trailer

Road

HAWC Tank Array in GEANT 4


Tanks Tanks vsvs PondPond•• Less expensiveLess expensive•• Build incrementallyBuild incrementally

–– Develop & debug as we Develop & debug as we are buildingare building

–– Within 2 yrs HAWC will Within 2 yrs HAWC will have 4x Milagro have 4x Milagro sensitivitysensitivity

•• Expandable & Expandable & upgradeableupgradeable

GEANT4 SimulationMuon (thinned 1/50) produces up to 100s of pes depending on impact parameter

100 MeV γ−ray (thinned 1/200) produces 1pe/60 MeV independent of impact parameter

See Poster by John Pretz


Site Location is Sierra Site Location is Sierra NegraNegra, Mexico, Mexico• 4100 m above sea level• Easy Access

• 2 hr drive from Puebla • 4 hr drive from Mexico City

• Existing Infrastructure• Few km from the US/Mexico

Large Millimeter Telescope• Power, Internet, Roads• Sierra Negra Scientific

Consortium of ~7 projects • Excellent Mexican

Collaborators• ~15 Faculty at 7 institutions

have submitted proposal to CONACYT for HAWC

• Experience in HEP, Auger, and astrophysics (including TeV)

See Poster by Alberto Carramiñana


HAWC CollaborationHAWC CollaborationUSA:

Los Alamos National Laboratory Brenda Dingus, John Pretz, Gus SinnisUniversity of Maryland Jordan Goodman, Andrew Smith, Greg SullivanUniversity of Utah Dave Kieda, University of New Mexico John MatthewsMichigan State University Jim LinnemannPennsylvania State University Ty DeYoungNASA/Goddard Space Flight Center Julie McEneryUniversity of New Hampshire James RyanUniversity of California, Irvine Gaurang Yodh

Mexico:Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE)

Alberto Carramiñana, Eduardo MendozaUniversidad Nacional Autónoma de México (UNAM)

Instituto de Astronomía: Magdalena González, Dany Page, William Lee, Hector Hernández, Deborah Dultzin, Erika BenitezInstituto de Física: Arturo Menchaca, Rubén Alfaro, Andres Sandoval, Ernesto BelmontInstituto de Ciencias Nucleares: Lukas Nellen, G. Medina-TancoInstituto de Geofísica: José Valdés Galicia, Alejandro Lara

Benemérita Universidad Autónoma de PueblaHumberto Salazar, Oscar Martínez, Cesar Álvarez, Arturo Fernández

Universidad Michoacana de San Nicolás de Hidalgo Luis VillaseñorCINVESTAV Arnulfo ZepedaUniversidad de Guanajuato

David Delepine, Gerardo Moreno, Marco Reyes, Luis Ureña, Victor Migenes


HAWC Sensitivity is HAWC Sensitivity is 15x Better than 15x Better than MilagroMilagro’’ss

e μ γ

(a)(a) Larger Effective Area at Larger Effective Area at Lowest EnergiesLowest Energies

(b)(b) Better Angular Better Angular ResolutionResolution

(c)(c) Improved Background Improved Background RejectionRejection

=> 10=> 10--15 x 15 x improvement in flux improvement in flux sensitivitysensitivity

=> (10=> (10--15)15)22 x faster to x faster to observe same flux observe same flux

(a)

(b)

(c)

100 GeV 1 TeV 10TeV 100 TeV



Had

ron

Effi

cien

cy

Ang

. Res

. (de

g)

E

ff. A

rea

(m2 )


• Gammas have NARROW lateral distribution of electrons

• Protons have BROAD lateral distribution of muons

Lateral Distribution of Extensive Air ShowersLateral Distribution of Extensive Air Showers


Gamma/Hadron SeparationGamma/Hadron Separation

Gam

mas

Prot

ons

30 GeV 70 GeV 230 GeV

20 GeV 70 GeV 270 GeVSize of HAWC

Size of Milagro deep layer

Energy Distribution at ground level

Rejection factor ~ e-<μ>


Background Rejection in MilagroBackground Rejection in MilagroProton MCProton MC Proton MCProton MC

DataData DataDataγγ

MCMC γγ

MCMC

Hadronic showers contain penetrating component: μ’s & hadrons

– Cosmic-ray showers lead to clumpier bottom layer hit distributions– Gamma-ray showers give smooth hit distributions


Milagro Background Rejection (ContMilagro Background Rejection (Cont’’d)d)

( )mxPE

nFitfOut+fTop=A ∗4

mxPE: maximum # PEs in bottom layer PMT

fTop: fraction of hit PMTs in Top layer

fOut: fraction of hit PMTs in Outriggers

nFit: # PMTs used in the angle reconstruction

S/B increases with increasing AS/B increases with increasing A4 4 so so analysis weights events by S/B as analysis weights events by S/B as determined by the Adetermined by the A44 value of the value of the eventevent

Background Rejection ParameterBackground Rejection Parameter


E F(>E

) (TeV/cm

2s)

Sensitivity to CrabSensitivity to Crab--like (like (dN/dEdN/dE=E=E--2.62.6) Point Source ) Point Source

GeV

•• HESS/VERITAS,HESS/VERITAS, MAGICMAGIC, , Whipple, Whipple, CTA CTA sensitivity in sensitivity in 50 hours, (~0.2 50 hours, (~0.2 srsr/year)/year)

•• GLASTGLAST sensitivity sensitivity in 1 year (4in 1 year (4ππ

srsr))

•• HAWC, HAWC, MilagroMilagro, , sensitivity in sensitivity in 1(solid) and 5 1(solid) and 5 (dashed) years (dashed) years (2(2ππ

srsr))

•• HAWC will do HAWC will do better for hard & better for hard & diffuse sourcesdiffuse sources

4 TeV6 TeV


HAWCHAWC’’ss Field of ViewField of View

= 2.6 π sr

= 1.8 π

sr


HAWC Science ObjectivesHAWC Science Objectives

•• Constrain the Constrain the origin of cosmic raysorigin of cosmic rays via via HAWCHAWC’’ss observations of observations of γγ--rays up to 100 TeVrays up to 100 TeV from discrete sources and the Galactic plane.from discrete sources and the Galactic plane.

•• Probe Probe particle accelerationparticle acceleration in extreme in extreme magnetic and gravitational fields via magnetic and gravitational fields via HAWCHAWC’’ss observations of transient TeV observations of transient TeV sourcessources, such as gamma ray bursts and , such as gamma ray bursts and supermassivesupermassive black holes.black holes.

•• Explore Explore new TeV physicsnew TeV physics via via HAWCHAWC’’ss unbiased sky surveyunbiased sky survey with a detection with a detection threshold of ~30 threshold of ~30 mCrabmCrab in two years. in two years.


CrabNebula

Mrk 421

Cygnus Region

HAWC’s science objectives build on the discoveries of Milagro


Distribution of Excesses in the Galactic Plane

cut level

CrabNebula

Mrk 421

•• 6.5 year data set (July 20006.5 year data set (July 2000--January 2007)January 2007)•• Weighted analysis using A4 parameterWeighted analysis using A4 parameter

–– Best data from 2004 on with outriggersBest data from 2004 on with outriggers•• Crab nebula 15 Crab nebula 15 σσ•• Galactic plane clearly visibleGalactic plane clearly visible

Cygnus Region


Abdo, et al. ICRC 2007

5.8 σ

4.5 σ

3.8 σ

C1 J2044+36

C2 J2031+33

MGRO J2031+41MGRO J2019+37

Tibet Excess

C3 J0634+17

Geminga

108 106

C4 J2226+60 EGRETE. Ona-Wilhelmi, et al., ICRC 2007


Abdo, et al. ApJ Lett 2007

GeV Sources Emit TeV GammaGeV Sources Emit TeV Gamma--RaysRays

•• Milagro has discoveredMilagro has discovered 3 new sources3 new sources & & 4 candidates 4 candidates in the Galaxy.in the Galaxy.•• 5/7 of these TeV sources have GeV counterparts.5/7 of these TeV sources have GeV counterparts. Only 13 GeV Only 13 GeV

counterparts in this region counterparts in this region -- excluding Crab. excluding Crab. Probability = 3x10Probability = 3x10--66

•• HAWC + GLAST observations survey the sky from 100 MeV to 100 TeVHAWC + GLAST observations survey the sky from 100 MeV to 100 TeV

LS I + 61 303

HESS J0632+057

IC443

H H


Milagro Extension of TeV spectrum of Milagro Extension of TeV spectrum of MGRO J1908+06 MGRO J1908+06 -- PreliminaryPreliminary

60 90

Median energy for this angle and α=-2.0 is 50 TeV Cut on A4> 4 & 9 gives median E of 60 and 90 TeV


•• Shower Fluctuations Shower Fluctuations Dominate Energy Dominate Energy ResolutionResolution

•• Higher Altitude of HAWC Higher Altitude of HAWC increases # of particles increases # of particles by ~6x by ~6x

•• Ability to measure a high Ability to measure a high energy cut off is a energy cut off is a combination of the combination of the energy resolution AND energy resolution AND the statistical error in the the statistical error in the fluxflux

HAWC Energy ResolutionHAWC Energy Resolution


HESS J1616-5080.2 Crab @ 1 TeV α=-2.3

Highest energy ~20 TeV


HESS J1616-5080.2 Crab @ 1 TeV α=-2.3


Simulated HAWC data for 1 year with no cutoff


HESS J1616-5080.2 Crab @ 1 TeV α=-2.3


Simulated HAWC data for 1 year with 40 TeV exponential cutoff


Sensitivity vs. Angular ExtentSensitivity vs. Angular Extent

Sextended ≈ Spointσ source

σ detector

σEAS ~0.5o σIACT ~0.1o

EAS large fov of 2 sr:

Entire source & background simultaneously observable

Background well characterized


Galactic Diffuse EmissionGalactic Diffuse Emission•• Probing cosmic ray origin Probing cosmic ray origin

requires distinguishing requires distinguishing between electron and between electron and hadron produced hadron produced γγ--raysrays

•• Hadrons are correlated Hadrons are correlated with matter density and with matter density and the flux is strongly the flux is strongly constrained by direct constrained by direct cosmic ray observationscosmic ray observations

•• Flux from electrons is Flux from electrons is less constrained, but less constrained, but must decrease at highest must decrease at highest energies due to Kenergies due to K--N N effectseffects

Hadronic Pion Decay

Electron Inverse Compton Scattering

GALPROP Conventional (solid) and Optimized (dashed) Models

Milagro Observation


Milagro Observations of Milagro Observations of Galactic Diffuse EmissionGalactic Diffuse Emission

Below HorizonCygnus Region

GALPROP (optimized)

Sources SubtractedHuntemeyer, et al. ICRC 2007

2.7x

GA

LPR

OP

1.5x

GA

LPR

OP

Cygnus Region with Matter Density Contours overlaying Milagro Significance

Source Subtracted Longitude Profile(see details in poster by Petra Huntemeyer)


Extragalactic Science: HAWC & TransientsExtragalactic Science: HAWC & Transients

GLAST and HAWC sensitivity for a source of spectrumdN/dE=KE-2

z=0 no E cutoffz=0.1 Eexp ~700GeVz=0.3 Eexp ~260GeVz=0.5 Eexp ~170GeV10

-12

10-1

010

-810

-6

TeV AGN flares

GRB <1 MeV

•• AGN and GRBs have bright flaresAGN and GRBs have bright flarese.g. PKS J2155e.g. PKS J2155--304 (z=0.117) flared to 50x quiescent flux in one hour 304 (z=0.117) flared to 50x quiescent flux in one hour with with dN/dEdN/dE=kE=kE--3.53.5 which would give which would give 6 6 σσ

in HAWCin HAWC


AGNsAGNs• HAWC will obtain duty factors and notify multiwavelength observers of

flaring AGN in real time.• Milagro has observed 7yr lightcurve of Mrk 421• HAWC’s increased sensitivity would result in ~10x smaller error bars

and have similar error bars on hour time scale rather than 64 days

Mila

gro

-Eve

nts/

day

AS

M F

lux

cts/

s

MJD - 500001/1/2000 1/1/2001 1/1/2002 1/1/2003 1/1/2004 1/1/2005 1/1/2006 1/1/2007

Milagro and XTE ASM 7 yr lightcurve of Mrk 421 (Smith et al. ICRC 2007)

Crab Flux


GRBsGRBs•• Milagro searches data within few seconds for Milagro searches data within few seconds for

short duration transients and sends alerts to short duration transients and sends alerts to GCN, but has found no significant emissionGCN, but has found no significant emission

•• HAWCHAWC’’ss low energy response allows dimmer low energy response allows dimmer GRBs at more distant GRBs at more distant redshiftsredshifts to be observed to be observed


HAWC sample GRB HAWC sample GRB lightcurvelightcurve

•• High Energy cut off High Energy cut off could occur due to could occur due to absorption in GRB absorption in GRB or in transit via EBL or in transit via EBL interaction.interaction.

•• Measurements of Measurements of lightcurvelightcurve reveal reveal information about information about progenitor and progenitor and constrains Lorentz constrains Lorentz invarianceinvariance..

HAWC lightcurve of a bright GRB (1e-4 ergs/cm2 fluence). Weaker burst counts scale with fluence.


Surveying the TeV SkySurveying the TeV Sky

•• Discovery PotentialDiscovery Potential•• Many Classes of Potential TeV Sources Many Classes of Potential TeV Sources

–– Extended SourcesExtended Sources•• Dark Matter, Galaxy clusters, AGN Pair Halos, Dark Matter, Galaxy clusters, AGN Pair Halos,

Molecular Clouds, . . .Molecular Clouds, . . .

–– Variable SourcesVariable Sources•• Compact Binaries, Compact Binaries, MicroquasarMicroquasar Flares, Solar Flares, Solar

Energetic Particles, . . .Energetic Particles, . . .


MilagroMilagro’’s Unexpected s Unexpected Cosmic Ray Anisotropy ObservationCosmic Ray Anisotropy Observation• Anisotropy on 10 deg size scale with a fractional excess

of 7e-4 above the cosmic ray background (15 σ)• Excess is not gamma rays, but charged cosmic rays (5 σ)• Largest excess is not consistent with the locally

measured cosmic ray energy spectrum (4 σ), but is harder with a cut off of ~10 TeV

• Explanations are difficult because the gyroradius of a 10 TeV proton in a 1 μG field is 0.01 parsecs

See Poster by Gary Walker


•• Milagro technique worksMilagro technique works–– Discovery of diffuse TeV gamma rays from Galactic plane & CygnusDiscovery of diffuse TeV gamma rays from Galactic plane & Cygnus regionregion–– Discovery of new Galactic TeV sources Discovery of new Galactic TeV sources –– Demonstration of longDemonstration of long--term multiterm multi--wavelength AGN monitoringwavelength AGN monitoring–– Unexpected TeV CosmicUnexpected TeV Cosmic--ray anisotropy observedray anisotropy observed

•• With HAWC Large improvements are possible With HAWC Large improvements are possible –– 1010--15 times the sensitivity of Milagro 15 times the sensitivity of Milagro –– ~5 ~5 σσ//√√day on the Crabday on the Crab–– 3% of Crab flux sensitivity over entire hemisphere (after 2 year3% of Crab flux sensitivity over entire hemisphere (after 2 year operation)operation)

•• Scientific CapabilitiesScientific Capabilities–– Highest energies Highest energies –– Extended sourcesExtended sources–– Galactic diffuse emissionGalactic diffuse emission–– TeV transients TeV transients –– Unbiased Sky surveyUnbiased Sky survey

ConclusionsConclusions


TeV TeV γγ

Rays: Rays: New Window on the SkyNew Window on the Sky

TeV gamma rayHESS

Milagro

Documents

HAWC - A Wide-Field Gamma-Ray Telescope · Brenda Dingus 8 Nov 2007 Complementarity Complementarity of TeV Gamma-Ray Detectors Imaging Air Cherenkov Telescopes Extensive Air Shower