Jamie Holder and Gernot Maier University of Delaware/ McGill University A summary of other...
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Jamie Holder and Gernot Maier University of Delaware/ McGill University
A summary of other A summary of other eventdisplay analysis results eventdisplay analysis results
from Fall 2006 and some from Fall 2006 and some other stuff wot I hav dun.other stuff wot I hav dun.
VERITAS Collaboration Meeting, Tucson, January 2007
• Results for November dark run
• Some other stuff
OverviewOverview
• All Observations taken during the November dark run
• Two-telescope data only
• major noise problems resolved
• relative gain gradient removed
• Loose run selection criteria
• Better than B weather
• No major hardware problems
Summary of ObservationsSummary of Observations
Summary of ObservationsSummary of Observations
Source Category Mean Elevation
Wobble offset
Exposure (hours)
Tycho SNR 56° 0.3° 11.7
PSR J2021 Pulsar/PWN 60° 0.3° 8.5
PSR J2229 Pulsar/PWN 57° 0.3° 11.3
1ES 0806 AGN 66° 0.3° 5.8
1ES 0647 AGN 73° 0.5° 12.4
Details of the sources will be presented this afternoon
AnalysisAnalysis• Eventdisplay/mscw_energy/anasum
• 5.0/2.5 σ pixel cleaning
• doublepass trace analysis
• Cleaning Cuts:• Two images with ≥5 pixels
• Hillas distance <1.2°
• Angle between image axes >10°
• Gamma Selection Cuts:• image size > 400 dc in each image
• mean-scaled width < 0.5
• mean-scaled length < 0.5
• θ2 < 0.025 (θ<0.158°)
Results: Ring BackgroundResults: Ring Background
Source ON events OFF events (normalisation)
Significance
Tycho 183 168.4 (0.23) 1.0
PSR J2021 214 209.8 (0.23) 0.3
PSR J2229 192 172.6 (0.23) 1.3
1ES 0806 89 76.0 (0.23) 1.3
1ES 0647 301 281.9 (0.23) 1.0
• Ring Background Details:
• Ring Radius = 0.5°
• Ring Width = 0.15°
Results: Reflected RegionResults: Reflected Region
Source ON events OFF events (normalisation)
Significance
Tycho 183 168.3 (0.33) 1.0
PSR J2021 214 216.3 (0.33) -0.1
PSR J2229 192 180.0 (0.33) 0.8
1ES 0806 89 80.7 (0.33) 0.8
1ES 0647 301 310.8 (0.20) -0.5
• Reflected Region Details:
• Fixed number of regions
• 3 for 0.3° offset
• 5 for 0.5° offset
Sky maps: Sky maps: TychoTycho
Ring BackgroundReflected Region
Background
Sky maps: Sky maps: PSR J2021PSR J2021
Ring BackgroundReflected Region
Background
Sky maps: Sky maps: PSR J2229PSR J2229
Ring BackgroundReflected Region
Background
Sky maps: Sky maps: 1ES 08061ES 0806
Ring BackgroundReflected Region
Background
Sky maps: Sky maps: 1ES 06471ES 0647
Ring BackgroundReflected Region
Background
Point source upper limitsPoint source upper limits
Source 3σ (99.87% CL) Upper Limit
(Counts)
% Crab Flux Previous limits (may not be
the best)
Tycho 72.3 5.0% 3.3% (HEGRA)
PSR J2021 64.7 5.6% 20% (Fegan)
PSR J2229 71.7 5.1% 21% (Fegan)
1ES 0806 48.6 5.6% 8% (de la Calle)
1ES 0647 72.1 3.5% 8% (HEGRA)
• Using Helene method
• Using Reflected Region results
• Crab % calculated using Crab rate at the mean elevation of the observations.
Swift Observations Swift Observations of LSI+61303of LSI+61303 BAT
15 - 150 keV
XRT0.3 - 10 keV
UVOT170-650nm
ObservationsObservations
September October November December
• 24 observations so far (as of December 19th)
• Total exposure ~50ksecs
• Observations ongoing
XRT ResultsXRT Results
• Strong detection with each exposure
XRT ResultsXRT Results
• Clear variability in light curve (factor of 5)
UVOTUVOT
• Images taken with a range of filters
• Mostly at shorter wavelengths
UVOTUVOT
• Example image with a blue filter
• LSI is one of the brightest objects in the frame
SummarySummary
• This was the multiwavelength state-of-the-art view before this year.
• Mainly non-contemporaneous
• Swift/VERITAS observations will greatly improve this
• We should keep observing LSI!
Jamie Holder University of Delaware
Magnetic Massive Stars as Magnetic Massive Stars as TeV source candidatesTeV source candidates
VERITAS Collaboration Meeting, Tucson, January 2007
• Wolf-Rayet stars generate strong stellar winds
• Integrated over their lifetime, the wind energy output is ~1037ergs/s
• In Wolf-Rayet binary systems (e.g. WR20a) winds from two 70Msol stars collide with a relative speed of ~1000 km/s
• This forms a shock region, where particle acceleration can occur (e.g. Bednarek 2005, Pittard 2006)
IntroductionIntroduction
• HESS have recently detected emission from the region of WR20a (9σ result)
• Extended ~0.2°
• Flux ~10-15% Crab
• Steady emission
• Spectrum ~Crab-like
• Offset w.r.t. WR20a
HESS ResultHESS Result
• WR 20a itself would be a point source
• Westerland 2, a stellar cluster with massive star formation (Chandra sees 500 X-ray sources here).
• Radio observations reveal wind blown "bubbles" around WR20a and WR20b and the core of Westerland 2, and a "blister" to the west, where the "bubble" is expands into a less dense region of the ISM.
HESS InterpretaionHESS Interpretaion
Radio Map (843MHz)
WR20a
WR20b
• Another colliding wind binary (Wolf-Rayet and O-type star)
• RA= 20h 20m, dec=+43 degrees
• Summer source (bad!), but unique to northern hemisphere (good!)
• Pittard & Dougherty:
• Integral predicted flux >1TeV= 1.2 × 10-14 photons s-1 cm-2
• requires >50 hours, but in the light of HESS result, who knows?
Northern hemisphere: WR140Northern hemisphere: WR140
• Most massive stars do not have strong magnetic fields; however, there exist a class of magnetic massive stars
• Bp stars: chemically peculiar (helium rich)
• Magnetic fields of ~ 10,000 Gauss
• These fields can channel the hypersonic, radiation-driven stellar wind into violent collision with itself, generating a shock of similar magnitude to a colliding wind binary system (Townsend and Owocki, 2006).
Northern hemisphere: Northern hemisphere: σσ Ori E Ori E
Northern hemisphere: Northern hemisphere: σσ Ori E Ori E • RA 05h 38m dec -02° 32'
• Visible now, to northern and southern hemispheres
• In the same field of view are star clusters; e.g. NGC 2024
• Chandra sees 283 sources in this star-forming region
• May have some trouble with bright stars...
• 10 hours in January would give us a strong upper limit on this new candidate source class.
NGC 2024The flame nebula