VERITAS Performance Gernot Maier

Transcription

1 VERITAS Performance Gernot Maier Alliance for Astroparticle Physics

2 What scientific impact will VERITAS have in the next 3-5 years? Galactic long-term plan Performance Operations LTP & Performance May 214 2

3 The next few years at very-high energies 7 y) 2 rra a l l u f 1 2 w no 7 ( mirror alignment T1 move 2,3-telescope operations HESS trigger upgrade camera upgrade Fermi MAGIC II HESS II HESS I camera upgrade MAGIC HAWC MILAGRO LTP & Performance May d2? n e ay t A n CT ume h Arr t r r t s o in? N e tiv 2 i s n y2 e s 3 arra t s mo ull? 1 2 8

4 VERITAS: Status May 214 see Nepomuk s talk > VERITAS started full operations in 27 2 and 3-telescope operations before this date > several major upgrades in the past years boost in sensitivity >3% (T1 move) lower energy threshold: <1 GeV (camera and trigger upgrade) better calibration - improved systematics (e.g. mirror alignment or flasher calibration) > data archive of >6 hours > very stable operations (~95%) no known critical hardware issues which would prevent us from operating >5 years > stable operational funding for the next years (DOE, NSF, SAO) LTP & Performance May 214 4

5 Require 5σ and >1 events per energy bin Sensitivity after Funk et al (CTA, 212) and Abeysekara et al 213 VERITAS 1 hrs 4 bins per decade energy (equal bin size on log scale) LAT - 5 yrs HAWC-1 1 yr CTA - 1 hrs HAWC 1 yr/5yrs Crab x.1 CTA - 1 hrs LTP & Performance May LAT(?)/HAWC: 24/7 duty cycle; IACTs

6 Detection Sensitivity 3σ is (of course) only an indication observation time [h] σ 3σ >1 events >1 events.5% - 1 h 1% - 25 h 5% h 1% -.5 h flux [Crab Units] LTP & Performance May 214 6

7 Future upgrades. analysis improvements observation time [h] σ is (of course) only an indication 5σ 3σ >1 events >1 events.5% - 1 h 1% - 25 h 5% h 1% -.5 h > VERITAS standard analysis based still based on image parameters > two new analysis methods almost methods almost ready for science use: MVA based (boosted decision trees) image template method > Significant improvements seen: 1% Crab in <2h flux [Crab Units] LTP & Performance May 214 7

8 Moonlight observations > new observation modes for increased temporal coverage ~85 hours of normal operations ~2 hours of moonlight operations (at nominal + reduced HV) ~25 hours of bright moonlight observations with UV filters in front of the cameras Optical Filter properties J.Holder LTP & Performance May 214 8

9 Effective areas - example ] 2 effective area [m Camera upgrade normal operation reduced HV UV filter pre-upgrade normal operation Preliminary energy [TeV] LTP & Performance May 214 9

10 Angular and energy resolution angular resolution [deg] Fermi LAT VERITAS HAWC Tycho 8 diameter.1 68%.5 containment radius energy [TeV] LTP & Performance May Abeysekara et al 213 LAT Performance page

11 LTP & Performance May

12 Large zenith angles 3-4% improvement in sensitivity for large zenith angle observations Crab Nebula observations at >55 deg VERITAS (214) Allows high-precision mapping of the inner Galaxy at energies >5 TeV LTP & Performance May

13 Pointing and systematic errors > pointing of each telescope is continuously monitored > systematic error on pointing less than 5 1 LTP & Performance May

14 Energy reconstruction E.3 energy resolution Fermi LAT VERITAS important for high-statistic studies of spectral cut offs energy [TeV] (note: strong dependence on quality cuts) LTP & Performance May

15 Systematic uncertainties in energy reconstruction > main sources for systematic uncertainties atmosphere calibration Monte Carlo simulations analysis > intensive work on improved calibration many values are measured now independently with different methods > as all systematic errors, extremely hard to estimate > assumed to be less than 2% on energy atmospheric profiles translation into flux uncertainty depends on spectral index, typically between 2 and 4% LTP & Performance May

16 Observational constrains observing hours / day Moon Monsoon VERITAS MJD LTP & Performance May

17 Observing the Galaxy with VERITAS Dots are known TeV sources LTP & Performance May Assuming elevations>5

18 Observing the Galaxy with VERITAS Dots are known TeV sources LTP & Performance May Assuming elevations>3deg

19 5 5 4 June March -1 July April August December Gernot Maier 1 LTP & Performance May 214 November October February September 1-1 Assuming elevations>3deg May Average elevation January

20 Summary > VERITAS is a mature VHE instrument with well understood performance and systematic errors > The coming 5 years will provide unprecedented wide-band coverage of the gamma-ray sky, along with complementary multi-messenger facilities > Galactic long-term plan discussions today: SNRs, PWN, Pulsars, Binaries, Surveys and discoveries LTP & Performance May 214 2