brenda dingus hawc review

Brenda DingusHAWC Review - December 2007

Scientific Objectives of HAWCScientific Objectives of HAWC

Brenda L. DingusBrenda L. Dingus

Los Alamos National LabLos Alamos National Lab


HAWC Scientific GoalsHAWC Scientific Goals

• Constrain the Constrain the origin of cosmic raysorigin of cosmic rays via via HAWC’s HAWC’s observations of observations of -rays up to 100 TeV-rays up to 100 TeV from discrete from discrete sources and the Galactic plane.sources and the Galactic plane.

• Probe Probe particle accelerationparticle acceleration in extreme magnetic and in extreme magnetic and gravitational fields via gravitational fields via HAWC’s observations of HAWC’s observations of transient TeV sourcestransient TeV sources, such as gamma ray bursts , such as gamma ray bursts and supermassive black holes.and supermassive black holes.

• Explore Explore new TeV physicsnew TeV physics via via HAWC’s unbiased sky HAWC’s unbiased sky surveysurvey with a detection threshold of ~30 mCrab in with a detection threshold of ~30 mCrab in two years. two years.


Galactic Sources of Cosmic RaysGalactic Sources of Cosmic Rays• Galactic Cosmic Rays extend to >1000 TeV (at least to the knee).Galactic Cosmic Rays extend to >1000 TeV (at least to the knee).• Gamma rays will be produced up to >100 TeV by these cosmic rays.Gamma rays will be produced up to >100 TeV by these cosmic rays.• Gamma rays produced by Inverse Compton scattering of electrons will Gamma rays produced by Inverse Compton scattering of electrons will

be suppressed by K-N effects.be suppressed by K-N effects.• HESS observes hard spectra sources, but are these the accelerators HESS observes hard spectra sources, but are these the accelerators

of cosmic rays? If so, their spectra should extend to > 100 TeV.of cosmic rays? If so, their spectra should extend to > 100 TeV.• HAWC has the sensitivity to measure spectra to the highest energies.HAWC has the sensitivity to measure spectra to the highest energies.

HESS Survey of the Inner Galaxy Reveals Extended Sources with average spectra of dN/dE=kE-2.3


• 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 J1616-508

0.2 Crab @ 1 TeV =-2.3

Highest energy ~20 TeV


HESS J1616-508

0.2 Crab @ 1 TeV =-2.3


Simulated HAWC data for 1 year with no cutoff


HESS J1616-508

0.2 Crab @ 1 TeV =-2.3


Simulated HAWC data for 1 year with 40 TeV exponential cutoff


Galactic Sources are ExtendedGalactic Sources are Extended

Sextended Spoint

source

detector

EAS ~0.5o IACT ~0.1o

HAWC’s large fov of 2 sr:

Entire source & background are simultaneously observable

Background is well measured


Galactic Diffuse EmissionGalactic Diffuse Emission

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

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

• HAWC + IACTs will detect HAWC + IACTs will detect additional localized sources to additional localized sources to extract true diffuse emissionextract true diffuse emission

• HAWC will measure the HAWC will measure the spectrum and spatial spectrum and spatial distribution to constrain the distribution to constrain the electronic and hadronic flux of electronic and hadronic flux of cosmic rays outside the solar cosmic rays outside the solar neighborhoodneighborhood

Hadronic Pion Decay

Electron Inverse Compton Scattering

GALPROP Conventional (solid) and Optimized (dashed) Models

Milagro Observation


Extragalactic Science: HAWC & TransientsExtragalactic Science: HAWC & Transients

• Active Galactic Nuclei (AGN) and Gamma Ray Bursts (GRBs)Active Galactic Nuclei (AGN) and Gamma Ray Bursts (GRBs)– Bright FlaresBright Flares– Rare EventsRare Events

• Large Field of View, High Duty Factor Observatories are Large Field of View, High Duty Factor Observatories are requiredrequired

EXAMPLE: PKS J2155-304 EXAMPLE: PKS J2155-304 (z=0.117) flared to 50x (z=0.117) flared to 50x quiescent flux in one hour quiescent flux in one hour with dN/dE=kEwith dN/dE=kE-3.5-3.5 which which would bewould be detectable bydetectable by HAWC (6 HAWC (6 ) as well as the ) as well as the moderate state observed in moderate state observed in prior weeks prior weeks

HESS Obs of 2155-304

http://www.journals.uchicago.edu/action/showFullPopup?doi=10.1086%2F520635&id=_e2


HAWC & GLAST Transient SensitivityHAWC & GLAST Transient Sensitivity

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


HAWC example GRB lightcurveHAWC example GRB lightcurve

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

• Measurements of Measurements of lightcurve reveal lightcurve reveal information about information about progenitor, such as bulk progenitor, such as bulk Lorentz factor of the Lorentz factor of the ejecta.ejecta.

• Best constraints on Best constraints on Lorentz invariance from Lorentz invariance from initial peak of the initial peak of the lightcurve.lightcurve.

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


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

transients and sends alerts to GCN, but has found no significant transients and sends alerts to GCN, but has found no significant emissionemission

• HAWC’s low energy response allows dimmer GRBs at more distant HAWC’s low energy response allows dimmer GRBs at more distant redshifts to be observed redshifts to be observed


TeV Emission From Short & Long GRBsTeV Emission From Short & Long GRBs

Short Bursts <2 secShort Bursts <2 sec Long Bursts >2 secLong Bursts >2 secNeutron Star Binaries CoalescenceNeutron Star Binaries Coalescence Supernova of Massive StarSupernova of Massive Star

~1/2 with z<0.5~1/2 with z<0.5 Few % with z<0.5Few % with z<0.5

Not Observable by IACTsNot Observable by IACTs Observable by IACTS after >50 secObservable by IACTS after >50 sec

z z

F(z

)

F(z

)


Active Galactic NucleiActive Galactic Nuclei• Open questions Open questions

– Protons or electrons?– Plasma Bulk Lorentz factor?– B-field?– Location of -ray production?– Acceleration mechanism?

• HAWC observationsHAWC observations– Many flares from known TeV AGN– New TeV AGN– Spectra > 1 TeV– Multiwavelength Observations with

other wide field observatories & by rapid notification

• HAWC scienceHAWC science– Average Flux & Spectra– Duty Cycle– Unbiased Survey– Constraints on Extragalactic

Background Light (EBL)


AGN MonitoringAGN Monitoring• HAWC will obtain duty factors and notify multiwavelength observers of

flaring AGN in real time.• All sources within ~2 sr would be observed every day for ~ 5 hrs.• HAWC’s continuous observations would not have gaps due to weather,

moon, or solar constraints. • HAWC’s 5 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


Mrk 421 with MilagroMrk 421 with Milagro• 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

- E

vent

s/da

y

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


Nearby AGNNearby AGN• M87 is a known, variable source of TeV M87 is a known, variable source of TeV -rays -rays

– HAWC will detect average flux at 5.8extending spectra to highest energies & monitoring variability

• Auger’s evidence for a correlation of UHECR with AGN point to other Auger’s evidence for a correlation of UHECR with AGN point to other nearby particle acceleratorsnearby particle accelerators– UHECR directions are deflected by several degrees, so individual

sources can’t be determined– However, UHECR will produce TeV gamma-rays near the sources

due to interactions with the CMB & infrared– HAWC can search the 100s of nearby AGN to find UHECR emitters

Auger’s 27 UHECRs (black circles) > 6e19eV & nearby, z<0.018, AGN (red *) plotted in Galactic coordinates with the SuperGalactic plane indicated by the dashed line

http://www.sciencemag.org/content/vol318/issue5852/images/large/318_938_F2.jpeg


Cosmology from EBL Absorption Cosmology from EBL Absorption

e+

e-

~eV

~TeV

• HESS & MAGIC constraints on the EBL HESS & MAGIC constraints on the EBL require the intrinsic spectrum of AGN is require the intrinsic spectrum of AGN is very hard very hard =-1.5) =-1.5)

– HAWC will increase the # of sources & the # of flares from the same source to decouple source dependent effects

• Highest Energy Spectra constrains longest Highest Energy Spectra constrains longest wavelength EBLwavelength EBL

– HAWC’s Spectra to > 10 TeV measures the dust temperature & impacts Galaxy Formation theories

• Pair Halos around AGN probes EBL at Pair Halos around AGN probes EBL at different ages of Universedifferent ages of Universe

– HAWC’s all sky survey of extended objects is required to find these halos

GLAST IACT HAWC


Surveying the TeV SkySurveying the TeV Sky

• Discovery PotentialDiscovery Potential• Many Classes of Potential Many Classes of Potential

TeV Sources TeV Sources – Extended Sources

• Dark Matter, Galaxy clusters, AGN Pair Halos, Molecular Clouds, . . .

– Variable Sources• Compact Binaries,

Microquasar Flares, Solar Energetic Particles, . . .


Astrophysical SourcesAstrophysical Sources• Known TeV sources such as x-ray binaries and microquasarsKnown TeV sources such as x-ray binaries and microquasars

– HAWC will monitor for flares and for periods difficult for IACTs (such as the 3.4 year period of PSR B1959-63 in which periastron aligned with the full moon)

• Postulated TeV sources such as Galaxy Clusters & GLAST sourcesPostulated TeV sources such as Galaxy Clusters & GLAST sources– HAWC’s field of view contains 100s of Galaxy Clusters within z<0.1

and will constrain the TeV flux of Galaxy Clusters as a class of TeV emiters

– >1/2 of GLAST sources will be within HAWC’s field of view

HESS x-ray binary obs. & HAWC’s sensitivity


• Particle-Antiparticle Annihilation Particle-Antiparticle Annihilation • WIMP neutralino, is postulated by SUSY • 50 GeV< m< ~ TeV

• HAWC can survey >2 sr for potential dark matter sources—nearby clumps, dwarf galaxies, clusters

• HAWC will monitor Galactic center for variability (a definite indication that the source is not dark matter)

• Primordial Black Hole EvaporationPrimordial Black Hole Evaporation• As mass decreases due to Hawking radiation, temperature increases

causing the mass to evaporate faster• Eventually temperature is high enough to create a quark-gluon plasma and

hence a flash of gamma-rays• HAWC’s continuous observation of >2 sr is necessary to find these

transients

Exotic SourcesExotic Sources

q

qor or Z

lines?


SummarySummary

• HAWC’s sensitivity will allow new observations HAWC’s sensitivity will allow new observations leading to new understanding of the high energy leading to new understanding of the high energy UniverseUniverse– Highest Energy HAWC Observations constrain

origin of cosmic rays– Wide field of view, High Duty Cycle probes the

transient TeV sky– Unbiased survey of >2 sr has discovery potential

for new TeV physics• HAWC’s scientific investigations are complementary HAWC’s scientific investigations are complementary

and enhance the scientific return of other current and and enhance the scientific return of other current and planned particle astrophysics observatoriesplanned particle astrophysics observatories

brenda dingus hawc review - december 2007 scientific objectives of hawc brenda l. dingus los alamos...

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