Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Detection of Tev  -rays from the Cygnus Region with Milagro Aous Abdo May 11, 2006 Santa Fe NM

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 The Milagro Tev  -ray Detector:  Water Cherenkov Detector  ~ 2 Steradian field of view  ~ 1.7 kHz data rate  898 detectors  450(t) / 273(b) in pond  175 water tanks  > 90 % duty cycle  ~ 0.5 Degree point spread function  0.1 – 100 Tev energy range 8 meters e  80 meters 50 meters Milagro Cross Section Schematic 10 m

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Aerial View of Milagro 175 Outrigger tanks (Tyvek lined – water filled) 2.4m diameter, 1m deep 1 PMT looking down

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Background Rejection in Milagro  Cosmic-ray induced air showers contain penetrating  ’s & hadrons  Hadronic showers result in a bright, compact clusters of light in the Muon layer  Gamma-ray showers illuminate the Muon layer uniformly with small hits Proton MC Data  MC

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Background Rejection (Cont’d) Parameterize “clumpiness” of the bottom layer hits  Compactness Require C > % gammas & 10% hadrons Sensitivity improved by 1.6 Require A 4 > % gammas & 1% hadrons Sensitivity further improved by 1.4 mxPE:maximum # PEs in bottom layer PMT nb2:# bottom layer PMTs with 2 PEs or more fTop:# fraction of hit PMTs in Top layer fOut:# fraction of hit PMTs in Outriggers nFit:# PMTs used in the angle reconstruction

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Test of New techniques on the Crab Nebula Combine A 4 with the weighting Analysis on 5 Years of Data Weight each event by Expected S/B Excess Signal = 3397 Background = 221,263 S/B = 1.5 * Excess Signal = 519 Background = S/B = 5.0 * A 4 > 3.0, nFit > 40 A 4 > 7.0, nFit > 40

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, st Results from Milagro on Galactic plane   -rays are predicted from p cr + p ism  p + p +  o  2   Therefore,  -rays sample cosmic ray flux and spectrum outside solar neighborhood  Milagro Detected Inner Galaxy (40 o <Gal. Long.<100 o ) in 3 years of data at 4.5   Outer Galaxy (140 o <Gal. Long.<200 o ) constrained with upper limit  Phys Rev Letter, Atkins et al years of data before outriggres were fully instrumented E -2.51±0.05

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Tev Sky Map Survey (Milagro 2003) Crab Nebula Mrk 421 >5  detections of Crab and Mrk 421 (AGN) 9 other points > 4  (consistent with background)

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Tev Sky Map Survey 2006  A 4 New Gamma-Hadron Separation Variable  Weighting Analysis  5 Years of data, 2 with outriggers used in event reconstruction providing much better sensitivity  Outriggers keep high energy gammas Crab Nebula > 14  Galactic Ridge clearly visible Cygnus Region discovery > 12  Preliminary

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 A Closer Look at the Galactic Plane Preliminary – GP diffuse excess clearly visible from l=25 O to l=90 O. – Cygnus Region shows extended excess – F Cygnus ~= 2x F Crab

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Cygnus Region Canadian Galactic Plane Survey - Far IR

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Cygnus Region Spatial Morphology  Contours are matter density  Crosses are EGRET sources  TeV/matter correlation good in Galactic latitude only  Brightest TeV Region –Coincident with 2 EGRET sources (unidentified) –Possible Pulsar wind nebula (similar to Crab) –Possible blazar (unlikely TeV counterpart) –TeV extended ~0.5 degrees –Hard spectrum at TeV  Diffuse region –Soft spectrum (~Cosmic Ray)  Analysis in progress

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 The Multiwavelength Milky Way

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Conclusions Milagro has proven the capabilities and importance of surveying the TeV sky with a large field of view, high duty cycle observatory. All-sky view has lead to significant discoveries  Diffuse  -ray emission from the Galactic plane –Diffuse emission from Cygnus region  Extended source coincident with 2 EGRET unidentified objects 2 more years of Milagro running will better constrain the fluxes, morphology and spectrum of TeV sources as well as place constraints on new classes of sources. Milagro is a complementary technique to atmospheric Cherenkov telescopes and space-based gamma-ray observatories. Milagro is a 1 st generation water Cherenkov detector and with the miniHAWC, 2 nd generation detector, major improvements in sensitivity are possible for moderate costs.

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Cygnus region Morphology and Spectral Determination with A 4 Divide the data in five epochs Slice each epoch in A 4 slices. 1.0 <= A 4 <= 20.0 in steps of 1.0 Simulate each epoch with the proper number of dead PMTs, core fitters, and reconstruction algorithms From these MC simulations find the proper G/H and Gaussian weightings for A 4 slices for each epoch. Weight each epoch separately. Add all the final weighted maps for all the epochs in one map (up to A 4 of 10.0) More to come! Summary

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Epochs Epoch 1: F0020 – F days of data. COM core fitter Epoch 2: F0032 – F days of data. Off core fitter Epoch 3: F0132 – F days of data. ORCOM core fitter Epoch 4: F0201 – F days of data. AS+MU+OR in Angular reconstruction Gauss core fitter Epoch 5: F0221 – F days of data. AS+OR in Angular reconstruction Gauss core fitter

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Evolution of Signals with time (epochs) Crab RegionCygnus Region

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 All Five Epochs Sky Map

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 All Five Epochs Crab Region : Crab : sigma at RA = 83.45, Dec = HotSpot D : 4.62 sigma at RA = 98.45, Dec = Nearest Source: Geming RA = 98.49, Dec = 17.86

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 All Five Epochs Inner Galaxy : HotSpot B : 4.84 sigma at RA = , Dec = Nearest Source: 87GB[BWE91] Radio Pulsar at RA = , Dec = HotSpot C : 5.61 sigma at RA = , Dec = Nearest Source: NVSS J Radio Pulsar at RA = , Dec = 5.49

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 All Five Epochs Cygnus Region : Cygnus HS: sigma at RA = , Dec = HotSpot A : 8.04 sigma at RA = , Dec = Nearest Source: 2EG J EGRET source at RA = , Dec = 41.32

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Spectral Determination A 4 is related to energy S/N increases with A 4 No loss of statistical accuracy!

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Spectral Determination (Cont’d)  Bin Data in A 4 : Differentially  Bin Gamma MC in A 4 for different spectral indices  Fit Differential Excess from data to the different gamma MC distributions  Calculate Chi Square for each fit  Minimum Chi Square corresponds to Spectral Index of source

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Crab Spectral Determination

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Crab Spectral Determination (Cont’d) Minimum Chi Square/ndf = 14.38/10 Alpha Crab = – 0.11 Results from other experiments in the same energy range: HEGRA: Tibet: Whipple: Off line data (626 days of data) Geant 4.0 V 1.2 No Noise 12 A 4 bins, A 4 [1,12) 1.3 degree square bin

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Crab Spectral Determination (Cont’d) On line data(epoch 4-5) 9 A 4 bins, A 4 [1,9) 2.1 Degree square bin

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Crab Spectral Determination (Cont’d) Alpha Crab < -2.9 On line data(epoch 4-5) G4Sim V 2.0 V.V. PMT corr included G4Sim V 2.0 No V.V. PMT corr. Minimum Chi Square/ndf = 7.15/7 Alpha Crab = A 4 bins, A 4 [1,9) 2.1 Degree square bin

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Cygnus HS Spectral Determination On line data(epoch 4-5) 9 A 4 bins, A 4 [1,9) 2.9 Degree square bin

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Cygnus HS Spectral Determination (Cont'd) Minimum Chi Square/ndf = 15.6/7 Alpha Crab = On line data(epoch 4-5) Geant 4.0 V 1.2 No Noise Geant 4.0 V 2.0 No Noise Minimum Chi Square/ndf = 13.35/7 Alpha Crab = A 4 bins, A 4 [1,9) 2.9 Degree square bin

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Cygnus HS Spectral Determination Minimum Chi Square/ndf = 14.6/7 Alpha Crab = On line data(epoch 4-5) G4Sim V 2.0 V.V. PMT corr included G4Sim V 2.0 No V.V. PMT corr. Minimum Chi Square/ndf = 13.8/7 Alpha Crab = A 4 bins, A 4 [1,9)

Aous Abdo Ground-based Gamma-ray Astronomy: Towards the Future. Santa Fe, NM May 11–12, 2006 Crab Spectral Determination (Cont’d) Minimum Chi Square/ndf = 8.48/7 Alpha Crab = On line data(epoch 4-5) G4Sim V 1.2 No Noise G4Sim V 2.0 No Noise No V.V. PMT corr. Minimum Chi Square/ndf = 6.75/7 Alpha Crab = A 4 bins, A 4 [1,9)