1. Alexander Moiseev SILAFAE 2010 December 6, 2010 Alexander Moiseev NASA Goddard Space Flight Center and University of Maryland for the Fermi LAT Collaboration Fermi Gamma-ray Space Telescope – science highlights for the first two years on orbit 1

2. Alexander Moiseev SILAFAE 2010 December 6, 2010 Fermi Gamma-ray Space Telescope was launched on June 11, 2008 1901 – 1954 … 2008 - …… “ There are two possible outcomes: If the result confirms the hypothesis, then you've made a measurement. If the result is contrary to the hypothesis, then you've made a discovery. “ Enrico Fermi 2

3. Alexander Moiseev SILAFAE 2010 December 6, 2010 The Fermi LAT Collaboration LAT collaboration France  IN2P3/LLR Ecole Polytechnique  IN2P3/CENBG Bordeaux  IN2P3/LPTA Montpellier  CEA/Saclay  CESR Toulouse Germany  MPI fuer extraterrestr. Physik, Garching Italy  INFN Bari, Padova, Perugia, Pisa, Rome, Trieste, Udine  ASI  INAF-IASF Japan  Hiroshima University  ISAS/JAXA  Tokyo Institute of Technology Spain  IEEC-CISC, Barcelona Sweden  Royal Institute of Technology (KTH)  Stockholm University United States  Stanford University (HEPL/Physics, SLAC, KIPAC)  UC Santa Cruz  Goddard Space Flight Center  Naval Research Laboratory  Sonoma State University  Ohio State University  University of Washington  University of Denver  Purdue University – Calumet LAT collaboration France  IN2P3/LLR Ecole Polytechnique  IN2P3/CENBG Bordeaux  IN2P3/LPTA Montpellier  CEA/Saclay  CESR Toulouse Germany  MPI fuer extraterrestr. Physik, Garching Italy  INFN Bari, Padova, Perugia, Pisa, Rome, Trieste, Udine  ASI  INAF-IASF Japan  Hiroshima University  ISAS/JAXA  Tokyo Institute of Technology Spain  IEEC-CISC, Barcelona Sweden  Royal Institute of Technology (KTH)  Stockholm University United States  Stanford University (HEPL/Physics, SLAC, KIPAC)  UC Santa Cruz  Goddard Space Flight Center  Naval Research Laboratory  Sonoma State University  Ohio State University  University of Washington  University of Denver  Purdue University – Calumet Spacecraft with LAT and GBM before shipping to KSC 3

4. Alexander Moiseev SILAFAE 2010 December 6, 2010 4 Fermi science objectives cover probably everything in high energy astrophysics:  How do super massive black holes in Active Galactic Nuclei create powerful jets of material moving at nearly light speed? What are the jets made of?  What are the mechanisms that produce Gamma-Ray Burst (GRB) explosions? What is the energy budget?  How does the Sun generate high-energy γ-rays in flares?  How do the pulsars operate? How many of them are around and how different are they?  What are the unidentified γ-ray sources found by EGRET?  What is the origin of the cosmic rays that pervade the Galaxy?  What is the nature of dark matter? Fermi Science Questions Multiwavelength observations in cooperation with gamma-ray, X- ray, radio, and optical telescopes

5. Alexander Moiseev SILAFAE 2010 December 6, 2010 Many discoveries in different topics. Fermi LAT Collaboration just has published its 100-th paper (~ 2,500 citations to date) Each of these papers is a complete high-level analysis covering one of the topics listed above. It is impossible to address all of them in one talk! I will briefly go through the main results. Please do not hesitate to ask me for the details off line 5 Fermi results recognized as one of the top 10 science breakthroughs of 2009 (Science, December 2009)

6. Alexander Moiseev SILAFAE 2010 December 6, 2010 6 Some Highlights Fermi LAT operated nearly flawlessly on orbit for more than 2 years and demonstrates excellent performance, which is continuously monitored and calibrated. LAT has collected > 100 billion on-orbit triggers Discovery and study of >70 gamma-ray pulsars, 24 of which are found in “blind” search. 16 are millisecond (or “recycled” pulsars) - 20 new millisecond radio-pulsars discovered thanks to LAT data (more are being found almost every week)! Remarkable high-energy emission from gamma-ray bursts Very high statistics measurement of the cosmic ray e + e - flux to 1 TeV Nailing down the diffuse Galactic GeV emission

7. Alexander Moiseev SILAFAE 2010 December 6, 2010 7 Some Highlights (cont.) First Fermi determination of the isotropic (extragalactic) diffuse flux Early searches for Dark Matter signatures in different kinds of sources Many new results on supermassive black hole systems (AGN), including sources never seen in the GeV range More cosmic accelerators: Galactic X-ray binaries and supernova remnants. Probing the cosmic ray distributions in other galaxies: M31, LMC and SMC Extragalactic Background Light constraints Year-one source catalog: 1451 sources High energy gamma-ray flares of Crab nebula detected

8. Alexander Moiseev SILAFAE 2010 December 6, 2010 8 Fermi Large Area Telescope (LAT)

9. Alexander Moiseev SILAFAE 2010 December 6, 2010 9 Two instruments onboard: Large Area Telescope LAT main instrument, gamma-ray telescope, 20 MeV - >300 GeV scanning (main) mode - 20% of the sky all the time; all parts of sky for ~30 min. every 3 hours GLAST Burst Monitor GBM 8 keV – 40 MeV observes whole unocculted sky all the time, searching for gamma-ray bursts

10. Alexander Moiseev SILAFAE 2010 December 6, 2010 10 Large Area Telescope LAT Heritage from OSO-III, SAS-II, COS-B, and EGRET, but: large field of view (2.4 sr at 1 GeV, 4 times greater than EGRET) and large effective area (~8000 cm 2 on axis at 1 GeV) Large energy range, overlapping with EGRET under 10 GeV and with HESS, MAGIC, CANGAROO and VERITAS above 100 GeV, including poorly- explored 10 GeV – 100 GeV range. observing strategy - uniform exposure and sky monitoringobserving strategy - uniform exposure and sky monitoring Good energy ( 100 MeV) and spatial resolution Unprecedented PSF for gamma-rays, >3 times better than EGRET for E>1GeV Small dead time (<30 μs, factor of ~4,000 better than EGRET) – GRB time structure! Excellent timing to study transient sources No consumables – chance for longer mission!

11. Alexander Moiseev SILAFAE 2010 December 6, 2010 11 The LAT Instrument Overview e+e+ e–e–  Pair-conversion gamma-ray telescope: 16 identical “towers” providing conversion of γ into e + e - pair and determination of its arrival direction (Tracker) and energy (Calorimeter). Covered by segmented AntiCoincidence Detector which rejects the charged particles background Silicon-strip tracker: 18 double-plane single- side (x and y) interleaved with 3% X 0 thick (first 12) and 18% X 0 thick (next 4) tungsten converters. Strip pitch is 228 μm; total 8.8×10 5 readout channels Hodoscopic CsI Calorimeter Array of 1536 CsI(Tl) crystals in 8 layers, 12 logs in each tower Segmented Anticoincidence Detector: 89 plastic scintillator tiles and 8 flexible scintillator ribbons. Segmentation reduces self-veto effect at high energy. Electronics System Includes flexible, robust hardware trigger and software filters. ~1.7 m ~ 1 m

12. Alexander Moiseev SILAFAE 2010 December 6, 2010 12 LAT Construction: An international effort

13. Alexander Moiseev SILAFAE 2010 December 6, 2010 13 1 – Transient class 2 – Source class 3 – Diffuse class multiple scattering dominates Finite pitch of Si strips LAT Performance One of the main features: most of the time the LAT is operating in the sky-scanning mode, making it all-sky monitor, unlike EGRET and AGILE, and especially ground- based ACTs 100 sec1 day 1 orbit1 year 10 -6 10 -7 10 -8 Flux > 100 MeV (phot cm -2 s -1 ) 1 3 2 These IRF values are “before launch” and subject for tuning during a mission Effective area PSF

14. Alexander Moiseev SILAFAE 2010 December 6, 2010 14 Gamma-Ray Sources

15. Alexander Moiseev SILAFAE 2010 December 6, 2010 - 1,451 sources 15 2FGL is in preparation

16. Alexander Moiseev SILAFAE 2010 December 6, 2010 > 1 GeV

17. Alexander Moiseev SILAFAE 2010 December 6, 2010 Pulsars in 1FGL: LAT Pulsar Catalog Comprehensive, uniform presentation of 46 pulsars detected by the LAT using the first 6 months of LAT data (now >60 LAT-detected pulsars) Comprehensive, uniform presentation of 46 pulsars detected by the LAT using the first 6 months of LAT data (now >60 LAT-detected pulsars) Of the 46, 16 resulted from blind searches, and 24 were discovered using ephemerides from radio monitoring*, including 8 MSPs Of the 46, 16 resulted from blind searches, and 24 were discovered using ephemerides from radio monitoring*, including 8 MSPs Light curves (with tabulated peak phases), spectral fits, log N-log S Light curves (with tabulated peak phases), spectral fits, log N-log S * Consortium of radio & X-ray astronomers; Smith et al. (2008) 17

18. Alexander Moiseev SILAFAE 2010 December 6, 2010 The Pulsing gamma-ray Sky. More than 60 gamma-ray pulsars are now known. Pulses at 1/10 th true rate 18 New pulsars discovered in a blind search Millisecond radio pulsars Young radio pulsars Pulsars seen by EGRET Fermi Pulsar Detection

19. Alexander Moiseev SILAFAE 2010 December 6, 2010 The Pulsing gamma-ray Sky. More than 60 gamma-ray pulsars are now known. Pulses at 1/10 th true rate

20. Alexander Moiseev SILAFAE 2010 December 6, 2010 AGNs in 1FGL: First LAT AGN Catalog (1LAC) Based on 1FGL sources associated with AGN, but for |b| > 10° & includes lower-confidence associations (down to P = 0.5) 671 1FGL sources: 300 BL Lacs, 296 FSRQs, 41 AGNs of other types, 72 of unknown type (some multiple associations) 1LAC paper also lists 51 low-latitude associations and 104 high-latitude ‘affiliations’ (plausible associations for which quantitative probabilities could not be defined) FSRQ BL Lacs Radio galaxies AGNs unknown type 20

21. Alexander Moiseev SILAFAE 2010 December 6, 2010 21 AGNs – most numerous sources (about half of 1FGL) detected by Fermi LAT Powered by accretion onto a central, supermassive black hole Powered by accretion onto a central, supermassive black hole Accretion disks produce optical/UV/X-ray emission via various thermal processes Accretion disks produce optical/UV/X-ray emission via various thermal processes Jets: highly collimated outflows with  10 Jets: highly collimated outflows with  10 Large brightness temps, superluminal motion, rapid variability in  -rays Unified Model: observer line-of- sight determines source properties, e.g., radio galaxy vs blazar Unified Model: observer line-of- sight determines source properties, e.g., radio galaxy vs blazar Other factors: accretion rate, BH mass and spin, host galaxy Other factors: accretion rate, BH mass and spin, host galaxy Image Credit: C.M.Urry & P. Padovani

22. Alexander Moiseev SILAFAE 2010 December 6, 2010 22 CTA 1 pulsar (2 cycles, P=315.86 ms) Gamma-ray source at l,b = 119.652, 10.468; 95% error circle radius =0.038° contains the X-ray source RX J00070+7302 Exhibits all characteristics of a young high- energy pulsar (characteristic age ~1.4 x 10 4 yr), which powers a synchrotron pulsar wind nebula embedded in a larger SNR. CTA 1 supernovae remnant RX J00070+7302 Fermi 95% error box 3EG J0010 +7309 95% error box  CTA 1 – First gamma-ray pulsar discovered by Fermi in blind search This source was a very bright AND well positioned unidentified EGRET source. This source was deliberately targeted during LAT checkout

23. Alexander Moiseev SILAFAE 2010 December 6, 2010 23 Acceleration in Magnetosphere Outer magnetosphere Near the NS surface LAT data consistent with simple exponential cut-off Favors outer-gap model Vela Pulsar – very first science analysis result for Fermi, used for calibration gamma-ray fan beam

24. Alexander Moiseev SILAFAE 2010 December 6, 2010 Pulsar Wind Nebulae - Powerful Particle Accelerators E>10 GeV counts map. PWN MSH 15-52 Crab Nebula Spectral Energy Distribution. Red points are Fermi LAT data, showing transition from synchrotron to Compton components. E>800 MeV Test Statistic (significance) map. PWN Vela X E>2 GeV counts map. PWN HESS J1640-465 Vela Pulsar 24

25. Alexander Moiseev SILAFAE 2010 December 6, 2010 Cygnus X-3 - Binary System - 4.8 Hour Period Gamma- rays X-rays Neutron star or black hole binary system, accelerating particles to high energies. The system remains largely a mystery. 25

26. Alexander Moiseev SILAFAE 2010 December 6, 2010 Supernova Remnants (SNR) - Spatially Resolved Strong evidence for cosmic ray production in SNR. Note: LAT does not resolve Cas A 26

27. Alexander Moiseev SILAFAE 2010 December 6, 2010 Supernova remnant W44 Spatially resolved. 2-10 GeV front-converting (high quality) events, deconvolved image. Green contours are from Spitzer IRAC, shocked H 2 Black cross is PSR B1853+01, not seen as a pulsed source. 27 Note: leptonic models are not excluded. Neutrinos could confirm the acceleration of hadrons by SNR. 27

28. Alexander Moiseev SILAFAE 2010 December 6, 2010 A Surprise - A Gamma-ray Nova In early March, the LAT skywatchers found a new, flaring gamma-ray source in the Cygnus region In early March, the LAT skywatchers found a new, flaring gamma-ray source in the Cygnus region To our surprise, we learned that an optical flare of the symbiotic system V407 Cyg (red giant/white dwarf binary) had occurred at about the same time. It was observed by amateur Japanese astronomers Koichi Nishiyama and Fujio Kabashima To our surprise, we learned that an optical flare of the symbiotic system V407 Cyg (red giant/white dwarf binary) had occurred at about the same time. It was observed by amateur Japanese astronomers Koichi Nishiyama and Fujio Kabashima 28

29. Alexander Moiseev SILAFAE 2010 December 6, 2010 Crab Flares in high energy! 10 arcsec Chandra Remnant from 1054 AD SN at 2 kpc Standard candle in X-rays and VHE Yearly variable in X-rays ~ 3.5%, 1- 150 MeV ~ 40% Spectrum between pulses (off-pulse) to remove pulsar contribution 29

30. Alexander Moiseev SILAFAE 2010 December 6, 2010 30 Two flares detected by Fermi LAT: Flux increase by a factor ~4 during ~ 16 days (January 26 to February 11, 2009) Flux increase by a factor of ~6 during ~4 days (September 18-22, 2010). First reported by AGILE No variation (< 5%) found in pulsed emission and nebula IC component monthly 4 days Photon index: 2.7 ±0.2 4.3 ±0.3 3.69 ±0.11 2nd flare 1st flare Second (short) flare has harder spectrum and extends > 1 GeV at >3σ Energy release small compared to pulsar spin down Crab Flares (cont.)

31. Alexander Moiseev SILAFAE 2010 December 6, 2010 31 Nothing unusual detected in Chandra and Hubble observations! Possible conclusions: The flare emission is synchrotron radiations from a small region, likely in the inner Nebula The presence of electrons to ≥ PeV (what is needed for such spectrum) is challenging to explain within diffusive shock acceleration model. Could be acceleration in the pulsar electric field By Y. Uchiyama

32. Alexander Moiseev SILAFAE 2010 December 6, 2010 Large Magellanic Cloud GeV gamma rays in these galaxies come primarily from the interactions of cosmic- ray hadrons and electrons with interstellar matter and photon fields. They are all seen in the light of their diffuse interstellar gamma-ray emission Gamma-ray emission from galaxies dominated by cosmic- ray interactions M82 NGC 253 Small Magellanic Cloud oo Small Magellanic Cloud Spectrum 32 Starburst galaxies

33. Alexander Moiseev SILAFAE 2010 December 6, 2010 − M31 flux measurement, along with measurements of MW, LMC, and SMC: − consistent with γ-ray luminosity L γ ~ 4 x 10 41 x SFR Smoothed, background- subtracted LAT γ-ray counts map; overlay: IRIS 100 μm contours (convolved with LAT PSF) 33 Nearby galaxy M31 (Andromeda) Star Formation Rate SFR (Msol yr -1 )

34. Alexander Moiseev SILAFAE 2010 December 6, 2010 LAT sees Sun and Moon The average integral flux measured with the LAT from the beginning of the mission to May 2010 for E>100MeV is: F = (1.21 ± 0.02 ± 0.2) × 10 -6 cm -2 s -1 Paper in preparation. 34

35. Alexander Moiseev SILAFAE 2010 December 6, 2010 The GBM detects ~250 GRBs/year (~540 total) ~18% short ~50% in the LAT FoV The LAT detects ~10 GRBs/year: 20 total as of today Fermi Gamma-ray Bursts 35

36. Alexander Moiseev SILAFAE 2010 December 6, 2010 Abdo et al. 2009, Science 323, 1688 Abdo et al. 2009, Nature 462, 331 GRB 080916C (long) GRB 090510 (short) 8-260keV 0.26-5MeV LAT all events >100 MeV >1GeV Properties: Delayed Onset Delay: ~0.5sDelay: ~5s Almost all GRBs show a delayed onset!of the high energy emission!! 36

37. Alexander Moiseev SILAFAE 2010 December 6, 2010 37

38. Alexander Moiseev SILAFAE 2010 December 6, 2010 Alexander Moiseev INFO-09 Santa Fe July 8, 2009 38 Spectra shown for mid-latitude range → EGRET GeV excess in this region of the sky is not confirmed Sources are a minor component LAT errors are systematic dominated and estimated to ~10% Galactic diffuse radiation, 100 MeV – 10 GeV, mid-latitude region

39. Alexander Moiseev SILAFAE 2010 December 6, 2010 Isotropic (extragalactic) background: do we know all its contributors? Components of the diffuse GeV background Not only unresolved blazars! 39 Fermi LAT spectrum can be fitted with a single power law with γ=2.41± 0.05, which is softer that the EGRET spectrum (~ 2.1) Basing on Fermi measurements of the blazar luminosity function, unresolved AGNs can account for up to 30% of the total isotropic background. This strongly depends on the point source sensitivity

40. Alexander Moiseev SILAFAE 2010 December 6, 2010

41. 41 Exotic sources

42. Alexander Moiseev SILAFAE 2010 December 6, 2010 The Dark Matter Problem 42

43. Alexander Moiseev SILAFAE 2010 December 6, 2010 Particle Dark Matter 43

44. Alexander Moiseev SILAFAE 2010 December 6, 2010 Many places to look! So far Fermi LAT set upper limits on DM constraints. No evident detection (yet) 44 Simulated sky map

45. Alexander Moiseev SILAFAE 2010 December 6, 2010 Data collected for the first 12 months of operation Total statistics 7.95 M electron candidate events More than 1000 events in highest energy bin (772 – 1000 GeV) Noticeable deviation from single power law spectrum Fermi LAT electron+positron spectrum 7 GeV – 1 TeV Ackerman et al., Fermi LAT Collaboration, Phys. Rev. D82, 092004, November 2010 (arXiv 1008.3999) PRELIMINARY Systematic error band 45 I will be talking about this work in detail on Wednesday

46. Alexander Moiseev SILAFAE 2010 December 6, 2010 46 Fermi LAT and scientific community

47. Alexander Moiseev SILAFAE 2010 December 6, 2010 47 Fermi works for the scientific community!

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50. Alexander Moiseev SILAFAE 2010 December 6, 2010 50 Conclusions Fermi LAT entered its 3-rd year of successful operation on orbit It works for the scientific community. The science data and main analysis tools are available for public Fermi LAT has already made many discoveries. But many more are coming Next Fermi Symposium will be held in Rome, Italy, on May 9-13, 2011. Join us!

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