the tev gamma-ray universe trevor c. weekes harvard-smithsonian center for astrophysics

The TeV Gamma-ray The TeV Gamma-ray Universe Universe

Trevor C. WeekesTrevor C. WeekesHarvard-Smithsonian Harvard-Smithsonian

Center for AstrophysicsCenter for Astrophysics

Motivation/Motivation/TechniquesTechniques

The TeV SkyThe TeV Sky

Future ProspectsFuture Prospects

Nu Vus of the Universe weekesNu Vus of the Universe weekes

A Lonely TeV Cosmic Ray


The Lonely TeV Proton takes a mate and produces a family;

many of the off spring go astray but dutiful gamma rays

carry on the family tradition and relay its message.


The Relativistic The Relativistic UniverseUniverse

The Relativistic Universe is defined by the presence of high energy particles, the sites where the particles are accelerated, the mechanisms by which they are accelerated, and the regions through which they propagate. Their presence is indicated by the emission of TeV gamma rays.


EGRET


Simple Technique,Simple Detectors,Low Budget

Collection Area = Size of Football Field


Development of GeV-TeVDevelopment of GeV-TeV

First Generation Systems 1960 – 1985First Generation Systems 1960 – 1985 Weak or no discriminationWeak or no discrimination Lebedev, Glencullen, Whipple, Narrabri, CrimeaLebedev, Glencullen, Whipple, Narrabri, Crimea

Second Generation Systems 1985 – 2004Second Generation Systems 1985 – 2004 Atmospheric Cherenkov Imaging Telescopes Atmospheric Cherenkov Imaging Telescopes Whipple, Crimea, CAT, HEGRA, Durham, CANGAROOWhipple, Crimea, CAT, HEGRA, Durham, CANGAROO …… ……

Third Generation Systems 2004 – 2010Third Generation Systems 2004 – 2010 Arrays of Large ACITsArrays of Large ACITs MAGIC, HESS, CANGAROO-III, VERITAS, MACEMAGIC, HESS, CANGAROO-III, VERITAS, MACE

Fourth Generation Systems 2010 -Fourth Generation Systems 2010 - TBDTBD

TeVSources

Zero

~ 12

> 100

1000?

New Technology

Increase in Scale

New Technology?


Development of MeV-GeVDevelopment of MeV-GeV First Generation Systems 1960 – 1972First Generation Systems 1960 – 1972

Spark ChambersSpark Chambers BalloonsBalloons ControversyControversy

Second Generation Systems 1972-1991Second Generation Systems 1972-1991 Spark Chambers Spark Chambers Small SatellitesSmall Satellites SAS-II, COS-BSAS-II, COS-B

Third Generation Systems 1991-2007Third Generation Systems 1991-2007 Spark ChamberSpark Chamber BiggerBigger EGRET on CGROEGRET on CGRO

Fourth Generation Systems 2007-2012+Fourth Generation Systems 2007-2012+ New Technology: Solid StateNew Technology: Solid State AGILE, GLASTAGILE, GLAST

100 MeVSources

One

30 (15)

270

10,000?

New Technology

Increase in Size

New Technology

What?

Early Expectations of TeV Gamma-Early Expectations of TeV Gamma-ray Astronomyray Astronomy

Find the Origin of the Cosmic Radiation:Find the Origin of the Cosmic Radiation:

* Single source or class of sources* Single source or class of sources

* Unambiguous detection of the 70 MeV * Unambiguous detection of the 70 MeV bump in the spectrumbump in the spectrum

* Source(s) would be in the Galaxy* Source(s) would be in the Galaxy

Locate the “Smoking Gun” of Cosmic Ray Locate the “Smoking Gun” of Cosmic Ray Origins!Origins!

The reality has been quite different!The reality has been quite different!

* Many different sources (too many!)* Many different sources (too many!)

* No unambiguous proton source detection* No unambiguous proton source detection

* Many sources are Extragalactic* Many sources are Extragalactic


Atmospheric Cherenkov Imaging Technique (ACIT)

Proposed in 1977*Imaging systems came into operation 1984 (Whipple, Crimea) *First TeV Source detected (Crab Nebula/Whipple Observatory) 1989 Standard Candle for TeV Gamma-ray AstronomyStrongest Steady Source in TeV Sky


TeV Image of Crab(not resolved)

Compton Synchrotron Model for TeV Gamma-ray emission (first proposed by Gould, 1964)Electron ProgenitorPrototype Model for most TeV gamma-ray sources

Synchrotron Compton

Detection of TeV Gamma-ray Detection of TeV Gamma-ray AGN AGN

Markarian 421

Weak Source in EGRET but strong at TeV energies

Markarian 421

Cross = X-ray sourceDotted line : EGRET error circleContours: TeV source intensity (29 sigma)

Variation in Nightly Rates from Markarian 421 Hours-days-months


TeV Catalog of AGNTeV Catalog of AGNCatalog NameCatalog Name SourceSource Date/GroupDate/Group Type Type RedshiftRedshift

TeV 1104+3813TeV 1104+3813 Mrk 421Mrk 421 1992/Whipple1992/Whipple HBLHBL 0.0310.031

TeV 1429+4240TeV 1429+4240 H1426+428H1426+428 2002/Whipple2002/Whipple HBLHBL 0.1290.129

TeV 1654+3946TeV 1654+3946 Mrk 501Mrk 501 1995/Whipple1995/Whipple HBLHBL 0.0330.033

TeV 2000+6509TeV 2000+6509 1ES1959+6501ES1959+650 1999/TA1999/TA HBLHBL 0.0480.048

TeV 2159-3014TeV 2159-3014 PKS2155-304PKS2155-304 1999/Durham1999/Durham HBLHBL 0.1160.116

TeV 2347+5142TeV 2347+5142 1ES2344+5141ES2344+514 1997/Whipple1997/Whipple HBLHBL 0.0440.044

Horan, Weekes, 2003

HBL = High frequency BL LacAll confirmed sourcesSpectra measuredLight-curves determinedMulti-wavelength CorrelationsOnly two in EGRET Catalog

Multiwavelength Results: Power Multiwavelength Results: Power SpectraSpectra

Synchrotron Compton

Mrk 501

Similar double peaked Power Spectra seen in other AGN

AGN Jet Emission MechanismsAGN Jet Emission Mechanisms

Electron Progenitors:Electron Progenitors:Synchrotron Self Synchrotron Self ComptonComptonExternal ComptonExternal Compton

Proton Progenitors:Proton Progenitors:Proton CascadesProton CascadesProton SynchrotronProton Synchrotron

Electron Synchrotron Self Compton Models most consistent with TeVAGN…..but observations are complex and require more sophisticatedModelling of Jets.

Limitations of ACIT Limitations of ACIT TelescopesTelescopes

Second Generation Telescopes Second Generation Telescopes successful but….successful but…. Limited Flux SensitivityLimited Flux Sensitivity Hitting the “Muon Wall”Hitting the “Muon Wall” Need Lower Energy for GLAST OverlapNeed Lower Energy for GLAST Overlap Array Concept demonstrated by HEGRAArray Concept demonstrated by HEGRA


ARRAYS (Third ARRAYS (Third Generation)Generation)

Arrays of Cherenkov telescopes viewing the same shower and improving the energy threshold, the angular resolution and the energy resolution; muon background removed.

Fac

Factor of 10-20 improvement in flux sensitivity

The Big 5 TeV ACIT ObservatoriesThe Big 5 TeV ACIT Observatories

CANGAROO III, 4 tel., 2006(Australia)

HESS, (Namibia) 4 tel., 2003 5 tel., 2007

VERITAS, (Arizona) 4 tel. 20067 tel. 2008?

MAGIC (La Palma), 1 tel., 2004 2 tel., 2008

MACE (India)2 tel. 2008

Iowa State University Adler PlanetariumIowa State University Adler Planetarium Leeds University Barnard CollegeLeeds University Barnard College McGill University DePauw UniversityMcGill University DePauw University National University of Ireland, Dublin Grinnell CollegeNational University of Ireland, Dublin Grinnell College Purdue University U.C. Santa CruzPurdue University U.C. Santa Cruz Smithsonian Astrophysical Observatory U. Mass.Smithsonian Astrophysical Observatory U. Mass. University of California, Los Angeles N.U.I., GalwayUniversity of California, Los Angeles N.U.I., Galway University of Chicago Cork I.T.University of Chicago Cork I.T. University of Utah Galway-Mayo I.T.University of Utah Galway-Mayo I.T. Washington University, Saint LouisWashington University, Saint Louis

Funding from NSF/DOE/Smithsonian/PPARC/SFI/NSERCFunding from NSF/DOE/Smithsonian/PPARC/SFI/NSERC

VERITAS: Very Energetic Radiation Imaging Telescope Array System

First two 12 m telescopes ofVERITAS now in operation at temporary site at Whipple Observatory Basecamp, December, 2005Four telescopes in operation in 2006Seven telescopes in 2008?

The VERITAS The VERITAS CollaborationCollaboration


1 GeV 100 GeV

GLAST (2 Years)

VERITAS-4(3 in 50 hrs)

Whipple 10 m (3 in 50 hrs)

Di

Differential Flux SensitivityDifferential Flux Sensitivity

VERITAS, HESS and MAGIC will overlap and complement GLAST


HESSEuropean Collaboration; M.P.I (Heidelberg)4 x 12 m TelescopesCompleted in Dec. 2003Located in NAMIBIA

First of the Big 5 to come on-line

Direction ~ arc-minEnergy Resolution ~ 10%Background ~ 0


The TeV Sky - 2005The TeV Sky - 2005

H1426

Mrk501

1ES1959

1ES 2344

PKS 2155

Cas A

RXJ 1713

CrabTeV 2032

M87

PKS 2005

PSR B1259

RXJ 0852

MSH 15-52

SNR G0.9

HessJ1303

GC

R.A.OngAug 2005

Pulsar Nebula

SNR

AGN

Other, UNID

H2356

1ES 1218

1ES 1101

LS 5039Vela X

CygnusDiffuse

Diverse Categories of TeV Gamma-ray sources:

AGN SNR (Plerion and Shell)

Radio Galaxy Microquasar

Galactic Plane Binary

Extended Sources Dark Sources

Galactic Center


Catalog of TeV AGN c. Catalog of TeV AGN c. 20052005

NameName zz ClassClass DiscoveryDiscovery

Markarian 421Markarian 421 0.0310.031 HBLHBL Whipple (Punch, 1992)Whipple (Punch, 1992)

Markarian 501Markarian 501 0.0340.034 HBLHBL Whipple (Quinn, 1996)Whipple (Quinn, 1996)

1ES 2344+5141ES 2344+514 0.0440.044 HBLHBL Whipple (Catanese, 1998)Whipple (Catanese, 1998)

1ES 1959+6501ES 1959+650 0.0480.048 HBLHBL T. A. (Nishiyama, 2000)T. A. (Nishiyama, 2000)

BL LacertaeBL Lacertae 0.0690.069 LBLLBL Crimea (Neshpor, 2001)Crimea (Neshpor, 2001)

PKS 2005-489PKS 2005-489 0.0710.071 HBLHBL H.E.S.S. (Aharonian, H.E.S.S. (Aharonian, 20052005))

PKS 2155-304PKS 2155-304 0.1170.117 HBLHBL Durham (Chadwick, 1999)Durham (Chadwick, 1999)

H 1426+428H 1426+428 0.1290.129 HBLHBL Whipple (Horan, 2002)Whipple (Horan, 2002)

H 1256-309H 1256-309 0.1650.165 HBLHBL H.E.S.S. (Aharonian H.E.S.S. (Aharonian 20052005))

BL 1219+305BL 1219+305 0.1820.182 HBLHBL MAGIC (MAGIC MAGIC (MAGIC 20052005))

BL 1101-232BL 1101-232 0.1860.186 HBLHBL H.E.S.S. (Aharonian H.E.S.S. (Aharonian 20052005))

3C66A3C66A 0.4440.444** LBLLBL Crimea (Neshpor, 1998)Crimea (Neshpor, 1998)


Gamma-ray Meets IR-Gamma-ray Meets IR-PhotonPhoton

-ray IR-photon

e+

e-

Absorption: exp(-)

Source: Source:

dN/dE ~dN/dE ~ EE-2-2

Spectrum at earth: E-2 exp(-)

• Extragalactic Background Light (EBL) causes spectral distortion due to + e+ + e- • Optical depth depends on integral over the EBL spectrum from the threshold for pair creation up to higher energies


EBL Detections & EBL Detections & LimitsLimits

From Dwek & Krennrich 2004, ApJ


HESS Survey: New SourcesHESS Survey: New Sources

HESS J1702-420HESS J1713-381 HESS 1632-478

330°

RX J1713.7-3946 HESS J1640-485HESS J1616-508

HESS J1614-518

359°

HESS J1708-410 HESS J1634-472HESS J1745-303

LS 5039

HESS J1804-216 Gal. Center HESS J1837-069

G0.9+0.1 HESS J1813-178 HESS J1825-137

HESS J1834-087

30° 0°

Sources > 6 sigma (9 new, 11 total)Sources > 4 sigma (7 new)


Microquasar: LS 5039Microquasar: LS 50397 sigma detection by HESSIdentification based on positionConsistent with EGRET SourceNo time variabilityHard spectumMicroblazar?


Relativistic Jets and TeV Relativistic Jets and TeV SourcesSources


Galactic Galactic CenterCenter

Hard spectrum Hard spectrum = 2.2. = 2.2. No evidence for variability onNo evidence for variability on

a variety of time scales.a variety of time scales.

Unlikely to be dark matter becauseUnlikely to be dark matter because

of energy spectrum.of energy spectrum.

HESS and MAGIC Spectrum

Good agreement between HESS andMAGIC.


RX J1713-394 RX J1713-394 (1)(1)

HESS Gamma: colorASCA X-ray: Lines

Hard spectrum ~ 2Not a simple power-law.

CANGAROO detection ~7.Shell Supernova RemnantHESS confirmation ~ 40Extended Bright SourceClose Correlation with X-raysSpectrumCosmic Ray Source?


RX J1713-394 RX J1713-394 (2)(2)

CO Distributions: Target Material?

Weak Radio

Progenitors: Electrons or Protons“No decisive conclusions can yet be drawn regarding the parent population

dominantly responsible for the gamma-ray emission from RX J1713.7-3946”

Not the Smoking Gun!

GLAST: the Next Generation Gamma-ray Space Telescope: 2007-2012

Future of GeV/TeV Gamma-ray Astronomy

Also smaller version: AGILE (2006)

Not clear what GeV space telescope might come after GLAST


Future of GeV/TeV Gamma-ray Astronomy (ground-based)

HESS-2: Add 28m telescope: improved sensitivity at lower threshold (50 GeV) in coincidence mode (stereo)

Fourth generation Observatories under discussion (>2010) e.g. HE-ASTRO proposed by Vladimir Vassiliev

Third generation Observatories coming on-line (<2008)It is easy to extend/scale-up ground-based observatories


HE-HE-ASTROASTRO

Because the size of the HE-ASTRO, ~1 km2, is much larger than the size of the Cherenkov light pool, ~108 cm2, the number of telescopes required is > 200

A

Coupling distance: d=80m


Array of 217 telescopesArray of 217 telescopes Elevation 3.5kmElevation 3.5km Telescopes’ coupling distance 80mTelescopes’ coupling distance 80m Area ~1.0kmArea ~1.0km22 (~1.6km (~1.6km22)) Single Telescope Field of View Single Telescope Field of View

~15~15oo

FoV area ~177 degFoV area ~177 deg22

Reflector Diameter ~7mReflector Diameter ~7m Reflector Area ~40 mReflector Area ~40 m22

QE 50% (200-400 nm)QE 50% (200-400 nm) Trigger sensor pixel size 0.146Trigger sensor pixel size 0.146oo

Trigger Sensor Size ~31.2cmTrigger Sensor Size ~31.2cm NSB rate per Trigger pixel ~3.2 pe NSB rate per Trigger pixel ~3.2 pe

per 20 nsper 20 ns Single Telescope NSB Trigger Rate Single Telescope NSB Trigger Rate

1KHz1KHz Energy Range 20–200 GeV Energy Range 20–200 GeV Differential Detection Rate Peak Differential Detection Rate Peak

~30 GeV ~30 GeV Single Telescope CR trigger rate Single Telescope CR trigger rate

~30 kHz~30 kHz

HE-ASTRO (specifications)HE-ASTRO (specifications) Image pixel size – 0.0146Image pixel size – 0.0146oo

Readout image – 128 x 128 pixelsReadout image – 128 x 128 pixels Readout Image size – Readout Image size –

1.8751.875oo x 1.875 x 1.875oo

NSB per pixel – 0.032 (20 nsec gate)NSB per pixel – 0.032 (20 nsec gate) ADC – 8 bit (S/N improved, ADC – 8 bit (S/N improved,

10– >8)10– >8) Pixel dimension 12mm x 12mmPixel dimension 12mm x 12mm Sensor area – 12.3 mm x 12.3 mmSensor area – 12.3 mm x 12.3 mm Shutter exposure – a few msecShutter exposure – a few msec Image integration time - 20 nsImage integration time - 20 ns Optical system TBDOptical system TBD Array trigger protocol TBDArray trigger protocol TBD Data Rates ~80 Mb/secper nodeData Rates ~80 Mb/secper node Online data processing TBDOnline data processing TBD

TeV Astrophysics Workshop, TeV Astrophysics Workshop, Palaiseau, April, 2005 (Vassiliev)Palaiseau, April, 2005 (Vassiliev)


Science coming soon Science coming soon (from (from a TeV Source near you)a TeV Source near you)

Astronomy and Astrophysics> 300 sourcesOld: SNR, AGN, Microquasars, Binaries, Dark Sources New: Clusters, Starburst, Pulsars, Others

Cosmological QuestionsEBL Measured Magnetic FieldsDistant Transients detected Lorentz Invariance

Origin of Cosmic RaysSources (ACIT Observatories) UHE SourcesDistribution (EAS Arrays) Galactic Plane

PhysicsDark Matter??GRBs ?? Prompt: ( Arrays EAS) PBHs Delayed: (ACIT Observatories)

Summary (1): The TeV Sky Summary (1): The TeV Sky (present)(present)

No Smoking Gun for Origin of the Cosmic Radiation …but Cosmic Particle Acceleration is Ubiquitous

Diverse Categories of TeV Gamma-ray sources: AGN SNR (Plerions and Shell) Radio Galaxies Microquasar Galactic Plane Binary Extended Sources Dark Sources Galactic Center

but no confirmed detections (yet!) of: Pulsars Clusters of Galaxies GRBs Starburst Galaxies UHE Sources

Summary (2): The TeV Sky Summary (2): The TeV Sky (future)(future)

Within a few years there will be five major ground-based gamma-ray observatories using the ACIT in operation.

The Next Generation of TeV Gamma-ray Observatories using the ACIT are now under discussion: (lower energy, wider fields, large collection area)

Watch this space!

These will be complemented by:Space Telescopes: AGILE, GLAST (lower E, wide field)Air Shower Arrays: Milagro, Tibet(high E, wide fields)Neutrino Telescopes: IceCube, KM3


Why study TeV Gamma-Why study TeV Gamma-rays?rays?

Why are Elephants the most popular animals in the zoo?

They are easy to see and they tell us much!


Cosmological studies of High Cosmological studies of High Energy Transient PhenomenaEnergy Transient Phenomena to determine:to determine:

Redshift evolution of these objectsRedshift evolution of these objects

Population properties of AGN and GRBsPopulation properties of AGN and GRBs

Redshift evolution of EBL (z=0-6)Redshift evolution of EBL (z=0-6)

Major contributors to EBL (stars, dust, AGN, Population III Major contributors to EBL (stars, dust, AGN, Population III objects, relic particles, SFR, GFR, IMF, BH accretion objects, relic particles, SFR, GFR, IMF, BH accretion histories, supernovae feedback, merger history)histories, supernovae feedback, merger history)

Cosmological magnetic fields and their evolutionCosmological magnetic fields and their evolution

High energy properties of space-timeHigh energy properties of space-time

the tev gamma-ray universe trevor c. weekes harvard-smithsonian center for astrophysics

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