Transcript Study of Galactic Gamma ray Sources with Milagro Milagro Jordan Goodman Jordan Goodman - The Milagro Collaboration Madison - August 2006 University of Maryland.

Study of Galactic Gamma ray
Sources with Milagro
Milagro
Jordan Goodman
Jordan Goodman
- The Milagro Collaboration
Madison - August 2006
University
of Maryland
Outline
• Brief Description of Milagro
• New results from Milagro
– Galactic Plane
– Cygnus Region
– Diffuse Source
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Milagro - A Water Cherenkov Detector
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Milagro
Jordan Goodman - The Milagro Collaboration
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Madison - August 2006
Milagro
• 2600m asl
• Water Cherenkov Detector
• 898 detectors
– 450(t)/273(b) in pond
– 175 water tanks
• 3.4x104 m2 (phys. area)
• 1700 Hz trigger rate
• 0.5o resolution
• 95% proton rejection
10 m
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Milagro Collaboration
• Los Alamos
– S. Casanova, B. Dingus, G. Sinnis, G. Walker
• U. Maryland
– D. Berley, R. Ellsworth, J. Goodman, C. Lansdell,
J. McEnery*, D. Noyes, A. Smith, Vlasios Vasileiou,
Buckley Hopper
• U.C. Santa Cruz
– D. Coyne, P. Saz Parkinson, D. Williams, L. Yang
• U.C. Irvine
– Branden Allen, T. Shoup, G. Yodh
• Michigan State University
– J. Linnemann, Aous Abdo
• U. New Hampshire
– J. Ryan
• NYU
– B. Kolterman, L. Fleysher, R. Fleysher, A. Mincer, P. Nemethy
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Milagro Detector
175 Outrigger tanks (Tyvek lined – water filled)
2.4m diameter, 1m deep
1 PMT looking down
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Event Reconstruction
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Milagro PSF
Time
Including
outriggers
Pond only
Degrees
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Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Milagro Area/Energy
Effective Area
Reconstructed g-ray energy
for Crab spectrum
Pond area
~5 m2 @100GeV
Milagro
Jordan Goodman - The Milagro Collaboration
3TeV
Median
Madison - August 2006
Background Rejection in Milagro
• Cosmic-ray induced air showers
contain penetrating m’s & hadrons
Proton MC
Proton MC
Data
Data
– Cosmic-ray showers lead to
clumpier bottom layer hit
distributions
– Gamma-ray showers gives
smoother hit distribution
g MC
Milagro
g MC
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Background Rejection (Cont’d)
• Parameterize “clumpiness” of the
bottom layer hits
– Compactness C =
nb2
mxPE
• Require C > 2.5
• 50% gammas & 10% hadrons
• Sensitivity improved by 1.6
A4 =
 fTop + fOut   nFit
mxPE
• Require A4 > 3.0
• 20% 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
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Signal to Noise
S/N increases with A4
No loss of statistical
accuracy!
Lack enough Monte Carlo Protons at high A4
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
A4 Weighting Analysis on the Crab Nebula
Combine A4 with the weighting Analysis on ~2 Years of Data
A4 > 3.0 , nFit > 40
A4 > 12.0 , nFit > 40
Weight each event
by Expected
S/B
Excess Signal = 2,074
Background = 60,637
S/B = 3.4%
Milagro
Jordan Goodman - The Milagro Collaboration
Excess Signal = 44
Background = 74
S/B = 60%
Madison - August 2006
Spectral Determination
A4 is related to energy
2-20 TeV useful range
Milagro
Parameterization of events
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Crab Spectrum (Preliminary)
See Poster by Branden Allen
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
TeV Sky Map Survey (Milagro 2003)
Mrk 421
Crab Nebula
>5  detections of Crab and Mrk 421
(AGN)
9 other points > 4  (consistent with
background)
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Sky Survey (Milagro today)
Cygnus Region
Mrk 421
Crab Nebula
Cygnus Region discovery ~12 
Crab Nebula ~14 
Galactic Ridge clearly visible
A4 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
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Sky Survey (Milagro today Unweighted)
Cygnus
Region
MRK 421
Crab
Our weighted analysis takes advantage of our improving
gamma-hadron separation with energy - this helps for hard
sources
Since MRK 421 cuts off it is not prominent in the new
weighted analysis
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Diffuse Emission from the Galactic Plane
• Diffuse emission from the Galaxy
is due to
– Proton matter interactions (p
component)
– Inverse Compton scattering of
high-energy electrons from CMB,
IR, optical photons (ISRF)
• EGRET observations to 20 GeV
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–
–
–
EGRET data
Milagro
Indicate a GeV excess
Stronger IC component?
Unresolved point sources
Dark matter?
• Higher energy observations
critical for understanding GeV
excess
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Significance
A Closer Look at the Galactic Plane
GP diffuse excess clearly
visible from l=25° to l=90°
Cygnus Region shows
extended excess
FCygnus ~ 2 x Fcrab
120 square degrees
l (65,85), b (-3,3)
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Profile of the Galaxy at 10 TeV
Galactic long. 20-100
1o bins in latitude
Galactic long. 120-220
1o bins in latitude
Galactic latitude -5 to 5
2 degree bins in longitude
(independent bins)
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
The Cygnus Region
• Complex region of
Galaxy
• But simpler than
Galactic Center
• 9 SNRs
• >20 Wolf-Rayet stars
• 6 OB associations
• Shocked gas
• Excellent Cosmic Ray
Laboratory
Canadian Galactic Plane
Survey - Far IR
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Cygnus Region Morphology
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Contours are pion
GALPROP model with no
sources
Crosses are EGRET
unidentified sources
TeV/matter correlation good
Chance noncorrelation 1.5x10-6
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Brightest TeV Region
– Coincident with 2
EGRET
sources (unidentified)
– Possible Pulsar wind
nebula (similar to Crab)
– TeV extended ~0.32
degrees
Diffuse region
Energy Analysis in progress
Flux (> 12.5 TeV) = 1.71 ± 0.24stat ± 0.34sys x 10-13 cm-2 s-1
(excluding new source & assuming E-2.6)
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Diffuse Emission from Cygnus
Region
• Strong & Moskalenko
standard model
Electron
Bremsstralung
p0
Milagro
p0
– Fit to EGRET < 1 GeV
– Increase p0 and IC
component throughout
Galaxy
– Milagro ~5x above
prediction
– Unresolved sources?
– Proton accelerators?
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Cygnus HotSpot MGRO J2019+37
High Energy Data
Crab
MGRO J2019+37
RA = 304.66◦ ± 0.13◦ Dec = 36.96◦ ± 0.08◦
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Diffuse Source MGRO J2019+37
Cut on nfit >150
These are highest energy/best fit events
Point source width ~0.4◦
Fit to 2-d Gaussian subtracting PS width
Crab
Gaussian Width = 0.32◦ ± 0.12◦
MGRO J2019+37
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
TeV: A New Window on the Sky
TeV Map coming soon
0.1 GeV
Milagro 10 TeV gamma-ray
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
Cygnus Region Multi-Wavelength
Radio Continuum (408MHz)
Atomic Hydrogen
Radio Continuum (2.5GHz)
Molecular Hydrogen
X-Ray
Gamma-Ray (100 MeV)
0.1 GeV
Gamma-Ray (10 TeV)
Milagro 10 TeV gamma-ray
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006
HAWC
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High
Altitude
Water
Cherenkov
experiment
Redeploy Milagro PMTs with Wider Spacing
Move to Higher Altitude
10-15 times more sensitive than Milagro
See Andy Smith’s talk later this session
Milagro
Jordan Goodman - The Milagro Collaboration
Madison - August 2006