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The Character of High Energy Emission From The Galactic Binary LS 1 +61 303. Andy Smith Smithsonian Astrophysical Observatory (for the VERITAS collaboration). LS 1 +61 303. -High Mass X-ray Binary -BH or NS? -26.496 day period -periodic outbursts in X-ray, radio, GeV , - PowerPoint PPT Presentation
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The Character of High
Energy Emission From The
Galactic Binary LS 1 +61
303Andy Smith
Smithsonian Astrophysical
Observatory
(for the VERITAS
collaboration)
LS 1 +61 303LS 1 +61 303
-High Mass X-ray Binary-High Mass X-ray Binary
-BH or NS?-BH or NS?
-26.496 day period-26.496 day period
-periodic outbursts in -periodic outbursts in
X-ray, radio, GeV,X-ray, radio, GeV,
and TeV gamma rays!and TeV gamma rays!
LS 1 +61 303LS 1 +61 303
Archival X-ray Archival X-ray
OutburstsOutbursts
(ROSAT,RXTE,(ROSAT,RXTE,
XMM-Newton)XMM-Newton)
LS 1 +61 303LS 1 +61 303
TeV EmissionTeV Emission
(MAGIC)(MAGIC)
LS 1 +61 303LS 1 +61 303
TeV EmissionTeV Emission
(MAGIC, VERITAS(MAGIC, VERITAS
LS 1 +61 LS 1 +61
303303
Radio Radio
EmissionEmission
(VLA, GBI)(VLA, GBI)
Microquasar or Binary Microquasar or Binary
Pulsar?Pulsar?
LS 1 +61 LS 1 +61
303303
Pulsar Model given support byPulsar Model given support by
VLBA monitoringVLBA monitoringNo X-ray or radio pulsations No X-ray or radio pulsations
detected, but…detected, but…Dhawan et al 2006Dhawan et al 2006
However, identification of However, identification of
system stillsystem still
an open issue- an open issue-
multiwavelength multiwavelength
observations observations
(with TeV) help to constrain (with TeV) help to constrain
rise time of rise time of
high energy emission in high energy emission in
different bandsdifferent bands
VERITAS LS I +61 303 Observations:VERITAS LS I +61 303 Observations:
- New TeV Array in S. Arizona (see
T.Weekes on Sat)
-Sensitive in range 100 GeV->20
TeV
-44h of data from September 2006-
February 2007
-Observations covered phase bins
0.2-0.9
->10 sigma detection in “active”
phase bins (0.5-0.8)
PhasesPhases
0.5->0.80.5->0.8
TeV activity coincides
with near-apastron
passage
Multiwavelength Multiwavelength
MonitoringMonitoring ToO observations approved for ToO observations approved for
SWIFT and RXTE in late 2006SWIFT and RXTE in late 2006
RXTE: 2-10 keV monitoring in RXTE: 2-10 keV monitoring in
OctoberOctober
SWIFT 0.2-10 keV monitoring Sep-SWIFT 0.2-10 keV monitoring Sep-
>Dec (PSU data reduction: >Dec (PSU data reduction:
A.Falcone,D.Morris) A.Falcone,D.Morris)
Flares observed by both instruments Flares observed by both instruments
around phases 0.6->0.7around phases 0.6->0.7
Contemporaneous observationsContemporaneous observations
during Tev/X-ray flaring statesduring Tev/X-ray flaring states
Very high flux seen in both bandsVery high flux seen in both bands
on same night- spectral analysison same night- spectral analysis
forthcomingforthcoming
Contemporaneous observationsContemporaneous observations
during X-ray flaring statesduring X-ray flaring states
X-ray emission elevated, X-ray emission elevated,
but not maximalbut not maximal
Local X-ray PeakLocal X-ray Peak
Local TeV PeakLocal TeV PeakTeV emission elevated,TeV emission elevated,
but not maximalbut not maximal
Active X-ray RegionsActive X-ray Regions
Active TeV regionsActive TeV regions
Summary so far…Summary so far… VERITAS observations confirm detection of LS 1 VERITAS observations confirm detection of LS 1
+61 303 as variable TeV source+61 303 as variable TeV source
One of 3 known “TeV” binaries- new class of One of 3 known “TeV” binaries- new class of
sourcessources
Multiwavelength observations show elevated TeV Multiwavelength observations show elevated TeV
emission correlated with elevated X-ray behavior emission correlated with elevated X-ray behavior
(not necessarily bijective....)(not necessarily bijective....)
SWIFT observations show secondary X-ray peak SWIFT observations show secondary X-ray peak
near pre-periastron passage- no TeV observations near pre-periastron passage- no TeV observations
yet for this region. yet for this region.
X-ray Peaks
TeV
Emission
Latest Observations……
MicroquasarMicroquasar
Scenario:Scenario:
Accretion Accretion
driven emission driven emission
during and during and
after density after density
peakspeaks. .
X-ray Accretion Disk-X-ray Accretion Disk-
->Radio Loud Jets->Radio Loud Jets
->Upscatter stellar photons->Upscatter stellar photons
to TeV energiesto TeV energies
Supporting Evidence:Supporting Evidence:
-MERLIN Imaging-MERLIN Imaging
-TeV emission agreeable with -TeV emission agreeable with
““Second Peak”Second Peak”
TeV
EmissionCons:Cons:
No spectral evidence for accretionNo spectral evidence for accretion
Where is primary peak?Where is primary peak?
Or……..Or……..
Binary Pulsar Binary Pulsar
Scenario:Scenario:Shock acceleration at interface between Shock acceleration at interface between
pulsar and stellar wind drives X-ray/TeV pulsar and stellar wind drives X-ray/TeV
emission- radio emission from cometary tailemission- radio emission from cometary tail
Observational Evidence:Observational Evidence:
-VLA imaging strongest evidence-VLA imaging strongest evidence
-Close rise time of X-ray/TeV emission-Close rise time of X-ray/TeV emission
Cons:Cons:
-No evidence for pulsations-No evidence for pulsations
-Is stellar wind stronger than pulsar wind?-Is stellar wind stronger than pulsar wind?
-Difficult to say without greater understanding-Difficult to say without greater understanding
of orbital geometryof orbital geometry
X-ray Peaks
TeV
Emission
Secondary X-ray Peak?Secondary X-ray Peak?
SummarySummary Latest high energy observations of LS 1 +61 303 Latest high energy observations of LS 1 +61 303
show evidence for correlation between X-ray and show evidence for correlation between X-ray and
TeV behaviorTeV behavior
No clear indication of fundamental identification of No clear indication of fundamental identification of
systemsystem
Regardless of nature (MQ vs BP) , it is evident that Regardless of nature (MQ vs BP) , it is evident that
“local“ compact systems are able to accelerate “local“ compact systems are able to accelerate
(most likely) electrons to TeV energies .(most likely) electrons to TeV energies .
TeV binaries represents ideal laboratories for TeV binaries represents ideal laboratories for
observations of high energy emission in the observations of high energy emission in the
presence of strong gravity stellar environments.presence of strong gravity stellar environments.
Watch this space.......Watch this space....... RXTE monitoring approved for bi-nightly RXTE monitoring approved for bi-nightly
observations from September 2007-->February observations from September 2007-->February
20082008
This, combined with TeV monitoring from This, combined with TeV monitoring from
VERITAS, will allow first multiwavelength VERITAS, will allow first multiwavelength
observations taken between phases 0.9->0.2: observations taken between phases 0.9->0.2:
more accurate measurement of full cycle more accurate measurement of full cycle
behaviorbehavior
If LS1 is a black hole, will add to study of BH If LS1 is a black hole, will add to study of BH
dynamics. If it is a binary pulsar, will add to dynamics. If it is a binary pulsar, will add to
study of pulsar wind accelerationstudy of pulsar wind acceleration