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Studying Active Galaxies with the Gamma-ray Large Area Space Telescope

Studying Active Galaxies with the Gamma-ray Large Area Space Telescope. Jennifer Carson SLAC/KIPAC for the GLAST LAT collaboration. Why care about gamma rays or GLAST?. Nature’s accelerators produce  rays To understand the high-energy universe, need  ray measurements

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Studying Active Galaxies with the Gamma-ray Large Area Space Telescope

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  1. Studying Active Galaxies with the Gamma-ray Large Area Space Telescope Jennifer Carson SLAC/KIPAC for the GLAST LAT collaboration

  2. Why care about gamma rays or GLAST? • Nature’s accelerators produce  rays • To understand the high-energy universe, need  ray measurements • GLAST is a huge improvement over previous missions • EGRET made ground-breaking discoveries, but was tip of the iceberg • Many unanswered questions for GLAST to address: high-energy GRB spectra? source populations? unidentified sources? Jennifer Carson - GLAST

  3. Outline • GLAST instruments • GBM description • LAT description, specs, sensitivity • Observatory status (spacecraft + GBM + LAT) • GLAST science • Overview of science goals • Capabilities for variability monitoring • Data access • Constraining AGN physics with GLAST • Time-resolved SEDs • Time-averaged SEDs: HBLs, LBLs, FSRQs Jennifer Carson - GLAST

  4. GLAST Observatory: Overview Lifetime: 5+ years Launch date: October/November 2007 LAT Large Area Telescope: ~20 MeV – >200 GeV 2.4 sr FoV GBM GLAST Burst Monitor: 8 keV – 30 MeV 9.5 sr FoV ~200 GRBs/year Jennifer Carson - GLAST

  5. GLAST LAT collaboration Principal Investigator: Peter Michelson (Stanford & SLAC) ~225 Members (~80 Affiliated Scientists, 23 Postdocs, and 32 Graduate Students) Cooperation between NASA and DOE, with key international contributions from France, Italy, Japan and Sweden. Managed at Stanford Linear Accelerator Center (SLAC). • France • IN2P3, CEA/Saclay • Italy • INFN, ASI • Japan • Hiroshima University • ISAS, RIKEN • Sweden • Royal Institute of Technology (KTH) • Stockholm University • United States • California State University at Sonoma • University of California at Santa Cruz - Santa Cruz Institute of Particle Physics • Goddard Space Flight Center – Laboratory for High Energy Astrophysics • Naval Research Laboratory • Ohio State University • Stanford University (SLAC and HEPL/Physics) • University of Washington • Texas A&M University, Kingsville Jennifer Carson - GLAST

  6. GLAST Burst Monitor (GBM) PI: Dr. Charles Meegan (MSFC) NaI crystals (12) low-energy spectral coverage 8 keV to 1 MeV BGO crystals (2) high-energy spectral coverage 150 keV to 30 MeV GBM http://f64.nsstc.nasa.gov/gbm/ 8 keV < E < 30 MeV (overlaps w/ LAT) FoV = 9.5 sr 12% energy resolution at 511 keV On-board localization: < 15° in 1.8s 2-3° localization in ~10s – minutes ~200 GRBs/year, > 50 in LAT FoV Jennifer Carson - GLAST

  7. Large Area Telescope (LAT) • Tracker (16 towers): • Facilitates pair conversion •  Tungsten conversion foils • Measures e-/e+ track •  18 layers of Si strips •  87 m2 of Si! • - > 800k channels ~20 MeV < E < ~300 GeV 2.4 sr FoV Anti-coincidence detector: - Segmented - Vetos CR background • Calorimeter: • - Measures photon energy •  1536 CsI crystals • “Hodoscopic” •  Allows shower profiling < 650 Watts Jennifer Carson - GLAST

  8. LAT instrument performance Angular Resolution (per ) Effective Area all layers thick thin http://www-glast.slac.stanford.edu/software/IS/glast_lat_performance.htm < 0.1° at E = 10 GeV < 0.35° at E = 1 GeV Src localization: ~0.5’ – 10’ 104 cm2 at 10 GeV Energy resolution: < 10% Jennifer Carson - GLAST

  9. All-sky scanning (“survey”) mode FoV = 2.4 sr, 90-min orbit Rocks +/-35° from zenith Jennifer Carson - GLAST

  10. Exposure comparison:Survey vs. pointed observations Survey mode Pointed mode position of Mrk 421 Pointed Survey Jennifer Carson - GLAST

  11. 1 year 5 years Point source sensitivity 4  10-9 cm-2 s-1 (E > 100 MeV) in 1 yr Thousands of sources! Jennifer Carson - GLAST

  12. Point source sensitivity 100 seconds EGRET Fluxes • - GRB940217 (100sec) • - PKS 1622-287 flare • - 3C279 flare • - Vela Pulsar • - Crab Pulsar • - 3EG 2020+40 (SNR g Cygni?) • - 3EG 1835+59 • - 3C279 lowest 5 detection • - 3EG 1911-2000 (AGN) • - Mrk 421 • - Weakest 5 EGRET source 90 minutes (1 orbit) In 1 day, detect (at 5) the weakest EGRET sources. In a few weeks, detect # of photons that EGRET detected in entire mission. Jennifer Carson - GLAST 1 day

  13. Where are we now? GBM is almost fully integrated onto spacecraft LAT starts integration today! Jennifer Carson - GLAST

  14. 55 days of GLAST science Catalogs Diffuse Emission AGN Pulsars & SNRs UIDs Galaxies Dark Matter GRBs Solar System Sources Realistic! Uncertainty in instrument response & background, + realistic science models Jennifer Carson - GLAST

  15. Data release and access • After 1st year: all data public immediately • During 1st year: • 60-day instrument check-out, then… • Automated science processing for time-critical science • Fluxes on ~20 “sources of interest” released weekly • Fluxes released on any source flaring above F (E > 100 MeV) = 210-6 cm-2 s-1 • Guest investigator program starts in 1st year (see S. Ritz talk at LBL in January) Jennifer Carson - GLAST

  16. DC2 input model Likelihood output Monitoring Variability with GLAST • Input models: - broken PL - Flux / correlation - quiescence + moderate flare • Likelihood model: - single PL - daily averages during low/moderate flux levels JC astro-ph/0610960 Threshold for 1st year public data release (~2/month) Jennifer Carson - GLAST

  17. DC2 input model Likelihood output Monitoring Variability with GLAST JC astro-ph/0610960 Daily hardness ratios Jennifer Carson - GLAST

  18. DC2 input model Likelihood output Monitoring Variability with GLAST JC astro-ph/0610960 Twelve-hour exposures Jennifer Carson - GLAST

  19. DC2 input model Likelihood output Monitoring Variability with GLAST JC astro-ph/0610960 Six-hour exposures Jennifer Carson - GLAST

  20. AGN science with GLAST LAT JC & J. Chiang 2006 http://www.oa.uj.edu.pl/2006jets/ Jennifer Carson - GLAST

  21. Setting the stage: blazars Radio-loud AGN viewed at small angles to the jet axis • bright core •  3% optical polarization • strong multi-wavelength variability Jennifer Carson - GLAST

  22. Setting the stage:blazar taxonomy FSRQs Fossati et al 1998, Donato et al. 2001 HBLs Jennifer Carson - GLAST

  23. Setting the stage:leptonic SSC/EC models Parameters of blob:RB, jet, B, ne, 1, 2, p SSC from HBLs EC + SSC from FSRQs Jennifer Carson - GLAST c.f. Böttcher et al. 1997, JC & J. Chiang in prep.

  24. Courtesy of J. Chiang X-ray LAT Snapshot SEDs with GLAST SED evolution w/ synch. cooling  Light curves on few-hour timescales  Rb/D  If cool ~ days (c.f. Böttcher & Chiang 2002)… - 12-hour exposures: F/F < 10%, / < 5%   track particle cooling after flares  measure  as e-s cool constrain B, 1, 2, p 12-hr exp  snapshot SEDs during cooling Expect dozens of srcs w/ these measurements JC astro-ph/0610960 Hardness ratios Twelve-hour exposures Jennifer Carson - GLAST

  25. HBLs and SSC models: past efforts Petry et al. 2000 • Simultaneous Mrk 501 data (1997) - RXTE, BATSE, HEGRA - Two epochs (1 week each) • Non-simultaneous EGRET data • One-zone, time-ave. SSC model: magnetic field B  blob radius RB  e-distribution (ne, p, 1, 2) • Data cannot constrain B and 1 • Need complete, simultaneous HE coverage! Mrk 501 Low state High state Jennifer Carson - GLAST

  26. HBLs: measuring SSC emission Unbinned analysis Simulated data LAT VERITAS sensitivity (courtesy R. Ong) Mrk 501 Jennifer Carson - GLAST

  27. HBLs: measuring SSC emission With joint LAT/TeV observations, cover the entire HE peak…  Constrain 1 & B Plus X-ray observations…  Probe relative contributions of Synch. & IC cooling  Measure all parameters: Rb, B, ne, p, 1, 2 Unbinned analysis X-ray LAT VERITAS Mrk 501 JC astro-ph/0610960 Jennifer Carson - GLAST

  28. FSRQs: Measuring EC emission 3C 279 •  Simultaneous data (Jan 1996): • - radio, mm, IR, optical • - UV, X-ray, -ray • Model includes all components: - Syn, SSC, ECD, ECC High state INTEGRAL SPI ECD SSC Hartman et al. 2001 ECC x BeppoSAX/LAT simulated counts  EGRET data Jennifer Carson - GLAST

  29. FSRQs: Measuring EC emission Constrains z & jet Constrained by variability 3C 279 high state ECD SSC Constrained by synchrotron component ECC Constrains BLR to better than 10% Jennifer Carson - GLAST

  30. LBLs: Distinguishing SSC and EC emission No EC radiation Model 5 Model 1 x X-ray/LAT sims  EGRET data Including EC radiation Model 9 Model 1 Jennifer Carson - GLAST W Comae Böttcher, Mukherjee, & Reimer 2002

  31. LBLs: Distinguishing SSC and EC emission No EC radiation W Comae Model 5 (BLR=0) Model 9 (BLR=310-3) Including EC radiation Model 1 (BLR=0) Can constrain BLR to < 310-3 Jennifer Carson - GLAST W Comae Böttcher, Mukherjee, & Reimer 2002

  32. Summary • The instruments • GBM is almost fully integrated with the spacecraft • LAT integration is just beginning • The strategy - Survey mode  entire sky every three hours - Thousands of new sources expected! • The AGN science • Track variability on hourly – weekly time scales • Snapshot SEDs  track particle cooling after flares • Time-averaged SEDs allow us to: • Constrain SSC models in HBLs • Distinguish between SSC and EC in LBLs • Constrain EC models in FSRQs • First GLAST Science Symposium • February 5-8 2007 at Stanford • Abstract deadline: Dec 15, early registration deadline: Dec 31 Jennifer Carson - GLAST

  33. Backup slides Jennifer Carson - GLAST

  34. LAT studies of pulsars Courtesy of Max Razzano Jennifer Carson - GLAST

  35. Dark matter in the gamma-ray sky Milky Way Halo simulated by Taylor & Babul (2005) All-sky map of DM gamma ray emission (Baltz 2006) Galactic center Milky Way satellites Milky Way halo Extragalactic Jennifer Carson - GLAST

  36. Expected LAT detections of blazars Mücke & Pohl 2000 C. Dermer astro-ph/0605402 Jennifer Carson - GLAST

  37. Expected LAT detections of blazars Number of blazars detectable by GLAST: 3000 - LDDE 5250 - PLE 10000 - SS96 Narumoto and Totani 2006 Jennifer Carson - GLAST

  38. Expected LAT detections of blazars Jennifer Carson - GLAST

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