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

A. Weinstein 4 Feb 2009 – Moriond Page 2 Outline  Introduction to VERITAS  VERITAS Galactic Science Program Overview Highlight results  Summary and future prospects

A. Weinstein 4 Feb 2009 – Moriond Page 3 85 m 109 m 82 m 35 m T1 Fall 2006 April 2007 T4 T2 T3 Since March 2006 ● FLWO,Mt. Hopkins, Az (1268 m asl) Specifications: ● Angular resolution ~ 0.1° ● Energy resolution~ % VERITAS at Whipple Observatory Sensitivity: ● 1% 5  ~ 47 hrs ● 5% 5  ~ 2.5 hrs Data, October 2007-June 2008: ● Good weather, 4-telescopes ~800 hours ● Moonlight ~100hrs → ~35% moonlight data this fall

A. Weinstein 4 Feb 2009 – Moriond Page 4 VERITAS 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/d 2 > 1x10 35 ergs/s/kpc 2 Composite and shell-type SNR Combination of dedicated and serendipitous observations (objects in FOV of other targets, survey)

A. Weinstein 4 Feb 2009 – Moriond Page 5 Galactic Science LSI Cas A MGRO J IC443 Crab Geminga AGILE PSR J PSR J PSR J

A. Weinstein 4 Feb 2009 – Moriond Page 6 Cas 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 TeV Power-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

A. Weinstein 4 Feb 2009 – Moriond Page 7 IC 443  Observed (wobble, 0.5º offset) during two epochs, for 37.1 hrs total livetime: Feb / Mar 2007 with 3 telescopes, PWN location Oct / Nov 2007 with 4 telescopes  Center of Feb/Mar hot spot:   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 (10 36 erg/s – 5 x erg/s)  Co-discovered (MAGIC/VERITAS) in TeV in 2007 PRELIMINARY PWN Green – Radio Red – Optical Blue – X-rays VERITAS position

A. Weinstein 4 Feb 2009 – Moriond Page 8 IC 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 production in cloud (1,2) associated with the pulsar wind nebula to the south (relic electrons?) (3) (1)Zhang, L. and Fang, J. Ap. J. 675 L21 (2008). (2)Torres, D. F. et al. arXiv: (3) Bartko, H. and Bednarek, W. arXiv: Elongation along cloud 2-D Gaussian profile fit Centroid: ± 0.03º(stat) ± 0.07º(syst) Extension: σ ~ 0.17º ± 0.02º(stat) ± 0.04º(syst)

A. Weinstein 4 Feb 2009 – Moriond Page 9 J.Casares et al (MNRAS 360, 1105 (2005)) LSI MW: Fermi VERITAS: phases MW: Swift, RXTE 50% moonlight data MW: Swift/RXTE ~45hrs ~21hrs Microquasar? Binary pulsar? ~25hrs

A. Weinstein 4 Feb 2009 – Moriond Page 10 LSI : RXTE(2-10keV) SWIFT(0.2-10keV) 8.4σ detection 7.3σ detection

A. Weinstein 4 Feb 2009 – Moriond Page 11 LSI : only Consistent with MAGIC Γ=2.40± 0.16 (stat) ±0.2 (sys) Consistent with spectrum Γ=2.6± 0.6 (stat) ±0.2 (sys) Phase-resolved ( )

A. Weinstein 4 Feb 2009 – Moriond Page 12 LSI Strong indication of orbit-to-orbit variability apastron σ detection 4.5σ detection No strong excess (2.6σ) 3.6σ pre-trials PRELIMINARY periastron

A. Weinstein 4 Feb 2009 – Moriond Page 13 Nov 2008 In Context PRELIMINARY Nov 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 -2 s -1 (2.1% Crab) Apastron, ?

A. Weinstein 4 Feb 2009 – Moriond Page 14 VERITAS 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 exposure at each point in the survey At least 6 hrs acceptance-corrected exposure at each point in the survey Survey analysis ongoing (release pending additional observations in April) Survey analysis ongoing (release pending additional observations in April)

A. Weinstein 4 Feb 2009 – Moriond Page 15 Significance Map (smoothed) MGROJ / HESS J  Needed a test case for Sky Survey extended source search, chose MGRO J /HESS J MGRO unidentified source  80% of Crab Nebula Flux, <2.6 ° diam. extension at 20 TeV Detected in HESS galactic plane survey  14% Crab flux > 300 GeV  Source extension 0.21 °± 0.07° (stat) ±0.05°(sys) PRELIMINARY  VERITAS Data taken under aegis of sky survey Data taken under aegis of sky survey ~22h of 4-telescope data 4.85σ detection 4.85σ detection ~0.19°± 0.04° extension ~0.19°± 0.04° extension position in agreement with HESS J position in agreement with HESS J

A. Weinstein 4 Feb 2009 – Moriond Page 16 AGILE  Observations (initially under moonlight) triggered by AGILE atels  7 hour exposure  99% upper limit at 2% Crab flux above 300 GeV.

A. Weinstein 4 Feb 2009 – Moriond Page 17 Future 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

A. Weinstein 4 Feb 2009 – Moriond Page 18 Summary  VERITAS Galactic science program in first 2 years has been fruitful SNR/PWN detections: Crab, CasA, IC443 UnID detections: MGRO J /HESS J Long-term observations (+MWL) of LSI have contained some suprises Expect: updated analyses of SNR detections (Cas A, IC443) Expect a number of new results by summer, including the Sky 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

A. Weinstein 4 Feb 2009 – Moriond Page 19 EXTRA/ BACKUP

A. Weinstein 4 Feb 2009 – Moriond Page 20 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 Candle

A. Weinstein 4 Feb 2009 – Moriond Page 21 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)

A. Weinstein 4 Feb 2009 – Moriond Page 22IC443 Green – Radio Red – Optical Blue – X-rays IC443

A. Weinstein 4 Feb 2009 – Moriond Page 23 IC 443  Observed (wobble, 0.5º offset) during two epochs, for 37.1 hrs total livetime: Feb / Mar 2007 with 3 telescopes, PWN location Oct / Nov 2007 with 4 telescopes  Center of Feb/Mar hot spot:   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 (10 36 erg/s – 5 x erg/s)  Co-discovered (MAGIC/VERITAS) in TeV in 2007 PRELIMINARY PWN