Results from Galactic Source Observations with VERITAS Amanda Weinstein for the VERITAS Collaboration Moriond, Feb. 4, 2009

Results from Galactic Source Results from Galactic Source Observations with VERITASObservations with VERITAS

Amanda Weinsteinfor the VERITAS Collaboration

Moriond, Feb. 4, 2009

A. Weinstein 4 Feb 2009 – Moriond Page 2

OutlineOutline

Introduction to VERITAS VERITAS Galactic Science Program

OverviewOverview

Highlight resultsHighlight results

Summary and future prospects


85 m

109 m

82 m35 m

T1

Fall 2006

April 2007

T4

T2

T3

SinceMarch

2006

● FLWO,Mt. Hopkins, Az (1268 m asl)

Specifications:● Angular resolution ~ 0.1°● Energy resolution ~ 15-20 %

VERITAS at Whipple ObservatoryVERITAS at Whipple Observatory

Sensitivity:● 1% Crab @ 5 ~ 47 hrs● 5% Crab @ 5 ~ 2.5 hrs

Data, October 2007-June 2008:● Good weather, 4-telescopes ~800 hours● Moonlight ~100hrs→ ~35% moonlight data this fall


VERITAS Galactic Science ProgramVERITAS Galactic Science Program

SNR/PWN Key Science Project

Cygnus Region Sky Survey(Key Science Project)

e.g. HMXBs, LMXBs, magnetars(microquasars)

Galactic Compact Objects

Dark accelerators…

Unidentified Objects

Strategy: search for TeV

PWN associated with pulsars

E/d2 > 1x1035 ergs/s/kpc2

Composite and shell-type

SNR

Combination of dedicated and serendipitous observations (objects in FOV of other targets, survey)


Galactic ScienceGalactic Science

LSI 61+303

Cas A

MGRO J1908+06

IC443

Crab

GemingaAGILE 2021+4024

PSR J0205+6449

PSR J1740+1000PSR J0631+1036


Cas ACas A Young (330yrs) SNR at a distance of ~3.4 kpc Massive star progenitor 5’ (4.5 pc) diameter (comparable to TeV angular

resolution) Discovered in TeV by HEGRA (232 hrs, 5 ),

confirmed by MAGIC (47 hrs, 5.3 )Flux ~ 3.3 % Crab above 1 TeVPower-law index of 2.3 ± 0.2stat ± 0.2sys

Well studied SNR in a relatively clean environment Extensive modeling of cosmic-ray acceleration and

gamma-ray production exists

VERITAS: wobble-mode observations, 0.5º offset, during Oct/Nov 2007 with 4 telescopes

Exposure: 20.3 hr: 9.8 detection Flux: ~ 3% Crab Consistent with a point source


IC 443IC 443

Observed (wobble, 0.5º offset) during two epochs, for 37.1 hrs total livetime:

Feb / Mar 2007 with 3 telescopes, Feb / Mar 2007 with 3 telescopes, PWN locationPWN location

Oct / Nov 2007 with 4 telescopesOct / Nov 2007 with 4 telescopes

Center of Feb/Mar hot spot:

06 16.9 +22 33

Flux ~3% Crab 8.2σ peak significance pre-trials

Middle-aged SNR ~ few – 10 kyr

SNR shell / molecular cloud interaction (beam dump)

PWN (southern edge): spin-down luminosity uncertain (1036 erg/s – 5 x 1037 erg/s)

Co-discovered (MAGIC/VERITAS) in TeV in 2007

PRELIMIN

ARY

PWN

• Green – Radio• Red – Optical• Blue – X-rays

VERITAS

position


IC 443IC 443

Not coincident w/radio/optical shell to northeast

Overlap with CO indicating molecular cloud along line of sight

Maser emission suggests SNR shock interacting with cloud

TeV emission could be

CR-induced pion CR-induced pion production in cloudproduction in cloud(1,2)(1,2)

associated with the pulsar associated with the pulsar wind nebula to the south wind nebula to the south (relic electrons?)(relic electrons?)(3)(3)

(1) Zhang, L. and Fang, J. Ap. J. 675 L21 (2008).(2) Torres, D. F. et al. arXiv:0804.2526.(3) Bartko, H. and Bednarek, W. arXiv:0712.2964.

Elongation along cloud

2-D Gaussian profile fit

Centroid: 06 16.9 +22 32.4 ± 0.03º(stat) ± 0.07º(syst)

Extension: σ ~ 0.17º ± 0.02º(stat) ± 0.04º(syst)


J.Casares et al (MNRAS 360, 1105 (2005))

LSI 61+303LSI 61+303

MW: Fermi

VERITAS: phases 0.2-0.9

MW: Swift, RXTE

50% moonlight data

MW: Swift/RXTE

~45hrs~21hrs

Microquasar?

Binary pulsar?

~25hrs


LSI+61 303: 2006-2008LSI+61 303: 2006-20082006-2007 2007-2008RXTE(2-10keV)

SWIFT(0.2-10keV)

8.4σ detection 7.3σ

det

ectio

n


LSI+61 303: 2006-2008LSI+61 303: 2006-2008

2006-2007 only

Consistent with MAGIC

•Γ=2.40± 0.16 (stat) ±0.2 (sys)

2007-2008

Consistent with 2006-2007 spectrum

•Γ=2.6± 0.6 (stat) ±0.2 (sys)

Phase-resolved (0.5-0.8)


LSI 61+303LSI 61+303

Strong indication of orbit-to-orbit variability

apas

tron

2007-20082006-2007 2008-2009

8.4σ detection

4.5σ detection

No strong excess (2.6σ)

3.6σ pre-trials

PRELIMINARY

PRELIMINARYpe

riast

ron


Nov 2008 In ContextNov 2008 In Context

PRELIMINARY

Nov. 2008 data part of a MWL campaign:

Fermi data (Dubois, AAS, 2009)detects the source continuously

Emission peaks at periastron

Sees clear periodicity

orbit-orbit variability(?)

VERITAS data: 99% upper flux limit:

F(E>500 GeV)< 1.26x10-12 cm-2s-1 (2.1% Crab)

Apastron, 2006-2007?


VERITAS Sky SurveyVERITAS Sky Survey

Partial survey of Cygnus region-1 < b < 4 and 67 < l < 82

Completed this fall (along with a small/moderate amount of followup)

At least 6 hrs acceptance-corrected At least 6 hrs acceptance-corrected exposure at each point in the surveyexposure at each point in the survey

Survey analysis ongoing (release Survey analysis ongoing (release pending additional observations in April)pending additional observations in April)


Significance Map (smoothed)

MGROJ1908+06 / HESS J1908+063

Needed a test case for Sky Survey extended source search, chose MGRO J1908+06/HESS J1908+063

MGRO unidentified sourceMGRO unidentified source 80% of Crab Nebula Flux, <2.6°

diam. extension at 20 TeVDetected in HESS galactic plane Detected in HESS galactic plane surveysurvey

14% Crab flux > 300 GeV Source extension 0.21°± 0.07° (stat)

±0.05°(sys)

PRELIM

INARY

VERITAS Data taken under aegis of sky surveyData taken under aegis of sky survey~22h of 4-telescope data ~22h of 4-telescope data 4.854.85σσ detection detection ~0.19°± 0.04° extension~0.19°± 0.04° extension position in agreement with HESS J1908+063position in agreement with HESS J1908+063


AGILE 2021+4024

Observations (initially under moonlight) triggered by AGILE atels 7 hour exposure 99% upper limit at 2% Crab flux above 300 GeV.


Future prospectsFuture prospects A new guide:

new Fermi pulsars, or sources w/PWNe associations → PWN searches, searches for pulsed emission from gamma-ray loud pulsars (if cutoff is favorable), new Fermi XRBs

GeV-TeV connection → disentangling nature of object, emission (e.g LSI, IC443…) Coordinated GeV-TeV observations


SummarySummary VERITAS Galactic science program in first 2 years has been

fruitfulSNR/PWN detections: Crab, CasA, IC443SNR/PWN detections: Crab, CasA, IC443UnID detections: MGRO J1908+06/HESS J1908+063UnID detections: MGRO J1908+06/HESS J1908+063Long-term observations (+MWL) of LSI 61+303 have Long-term observations (+MWL) of LSI 61+303 have contained some suprisescontained some suprisesExpect: updated analyses of SNR detections (Cas A, IC443)Expect: updated analyses of SNR detections (Cas A, IC443)Expect a number of new results by summer, including the Expect a number of new results by summer, including the Sky SurveySky Survey

Moving T1 will improve our sensitivity to galactic sources Fermi data and VERITAS Sky Survey results will likely

modify our observing strategy for the coming year


EXTRA/BACKUP


1% Crab in 47 hours

5% Crab in 2.5 hours

5σ Detection Sensitivity

Measured sensitivity to the Crab Nebula at high elevation (>65°)

HESS ~1% Crab in 25 hours (but mirror reflectivity now degraded)

MAGIC ~2% Crab in 50 hours

Measured sensitivity to the Crab Nebula at high elevation (>65°)

HESS ~1% Crab in 25 hours (but mirror reflectivity now degraded)

MAGIC ~2% Crab in 50 hours

The Crab: A Standard CandleThe Crab: A Standard Candle


Geminga Geminga

VERITAS Observations: 13.3 hours at high elevation Upper Limit to steady emission(>300 GeV): <2x10-8 γ/m2/s

(~1% Crab flux) Upper Limit to pulsed emission(>300 GeV): <1x10-8 γ/m2/s

(~0.5% of Crab flux)


IC443IC443

• Green – Radio• Red – Optical• Blue – X-rays

IC443


IC 443IC 443

Observed (wobble, 0.5º offset) during two epochs, for 37.1 hrs total livetime:

Feb / Mar 2007 with 3 telescopes, Feb / Mar 2007 with 3 telescopes, PWN locationPWN location

Oct / Nov 2007 with 4 telescopesOct / Nov 2007 with 4 telescopes

Center of Feb/Mar hot spot:

06 16.9 +22 33

Flux ~3% Crab 8.2σ peak significance pre-trials

Middle-aged SNR ~ few – 10 kyr

SNR shell / molecular cloud interaction (beam dump)

PWN (southern edge): spin-down luminosity uncertain (1036 erg/s – 5 x 10 1037 erg/s)

Co-discovered (MAGIC/VERITAS) in TeV in 2007

PRELIMIN

ARY

PWN

Documents

Results from Galactic Source Observations with VERITAS Amanda Weinstein for the VERITAS Collaboration Moriond, Feb. 4, 2009