Overview of Fermi Gamma-ray Telescope

Lecture with a general overview of the Fermi Gamma-ray Space Telescope, with particular focus on the Large Area Telescope (Fermi LAT).

Structure:
• Gamma-ray astronomy
• How Fermi LAT works
• Cosmic γ sources
• Multimessenger astronomy w/ Fermi
• Hands-on activity

Transcript

1. Overview of Fermi Gamma-ray Telescope Rodrigo Nemmen Universidade de Sao Paulo elescope aunch June 11, 2008 Celebrating 0th year Anniversary
2. Structure of this talk Gamma-ray astronomy How Fermi LAT works Cosmic γ sources Hands-on activity
3. The extreme universe shines in gamma-rays TODO: put slide with relevant frequencies and energies phenomena relevant at the different frequencies electron, proton rest mass energy
4. credit: https://imagine.gsfc.nasa.gov/science/toolbox/ emspectrum_observatories1.html
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6. ms: the QED vertex e fermion that matters (can be lepton or quark) s can be combined and momentum must be annihilation pair creation 5 s of Particle Detectors Some important Feynman diagrams for astroparticle physics actions – Examples Pair production: x γ Electron Positron Electron Photon Electron Positron Nucleus Compton scattering: γ γ Electron Electron Photon Photon Electron gnetic interactions of electrons nd photons in matter (inverse) Compton scattering Pair production Bremsstrahlung electron ion ion electron γ GAMMA-RAY 2. GENERAL RELATIONS 2.1. Pion Production The production of c-rays from p-p collisions is a two process, and has been worked out in detail by St see also & Badhwar Dermer (1971; Stephens 1981; 1 The colliding protons produce an intermediate 1986b). ticle, a neutral pion, n0, which then decays into two photons. The reaction is p ] p ] p ] p ] n0 , n0 ] c 1 ] c 2 , where the photons, in general have di†erent ene c 1, c 2, in the gas frame. The number of neutral pions produc GAMMA-RAY EMISSION FROM 2. GENERAL RELATIONS 2.1. Pion Production The production of c-rays from p-p collisions is a two-step cess, and has been worked out in detail by Stecker see also & Badhwar Dermer 71; Stephens 1981; 1986a, The colliding protons produce an intermediate par- 6b). e, a neutral pion, n0, which then decays into two c-ray otons. The reaction is p ] p ] p ] p ] n0 , n0 ] c 1 ] c 2 , (1) ha (1986b) experiment threshold: gies Ep Z 8 rep (1981) In 1986b). models in t smoothly ( To evalu proton-proton collision followed by neutral pion decay
7. Ground-based: indirect detection via Cherenkov radiation Space-based: direct detection using techniques of particle physics Types of gamma-ray observatories
9. Fermi Gamma Ray Telescope: 20 MeV - 300 GeV, covers whole sky every 3 hours Unique Capabilities for GeV astrophysics – Large effective area – Good angular resolution – Huge energy range – Wide field of view Large Area Telescope (LAT) Observes 20% of the sky at any instant, entire sky every 3 hrs 20 MeV - 300 GeV Gamma-ray Burst Monitor (GBM) Observes entire unocculted sky Detects transients from 8 keV - 40 MeV International and interagency collaboration between NASA and DOE in the US and agencies in France, Germany, Italy, Japan and Sweden Mission Lifetime: 5 year requirement, 10 year goal R. Nemmen
12. All observed data is immediately public, as well as analysis software Google for: Fermi LAT data
13. Fermi LAT: real time movie of the gamma-ray sky 20 MeV - 300 GeV
14. Gamma-ray sky after 7 years Bühler+15 Energies 100 MeV - 300 GeV
15. Types of sources seen by Fermi LAT Acero+15
16. Slide: J. McEnery
17. Active galactic nuclei
18. ≈60% of gamma-ray sources are black holes supermassive black holes Broad band emission models (1) Leptonic: (a) Synchrotron self-Compton (b) External Compton (2) Hadronic: A. Dominguez
19. 0 0 −30 30 −60 60 −90 90 −120 120 −150 150 −180 180 30 −30 60 −60 90 −90 Ackermann+15 Gamma-ray sky observed by Fermi LAT is dominated by blazars FSRQs: flat spectrum radio quasars BL Lac objects AGNs of unknown type non-blazar AGNs
20. Apparent size of Moon Centaurus A: 20 times bigger than the Moon in radio and gamma-rays
21. How can a black hole emit gamma-rays? It doesn't
22. McKinney et al. 2013, Science also, work in progress by Soares et al. electron γ electron γ Inverse Compton scattering: - self-synchrotron - external
23. Launching of Active Galactic Nuclei Jets 19 toward the polar regions as they move away from the BH. The group of field lines highlighted in green connects to the BH and makes up the twin polar jets. The jet field lines extract BH rotational energy and carry it away to large distances. These field lines have little to no gas attached to them and are therefore highly magnetized (since disk gas cannot cross magnetic field lines and is thus blocked from getting to the polar region, the jet field lines either drain the gas to the BH or fling the gas Fig. 9 [Panel (a)]: A 3D rendering of our MAD a = 0.99 model at t = 27,015rg /c (i.e., the same time as Fig. 8d). Dynamically-important magnetic fields are twisted by the rotation of a BH (too small to be seen in the image) at the center of an accretion disk. The azimuthal magnetic field component clearly dominates the jet structure. Density is shown with color: disk body is shown ith yellow and jets with cyan-blue color; we show jet magnetic field lines with cyan bands. The s approximately 300rg ⇥800rg . [Panel (b)]: Vertical slice through our MAD a = 0.99 e and azimuth over the period, 25,000rg /c  t  35,000rg /c. Ordered, fields remove the angular momentum from the accreting gas pinning BH (a = 0.99). Gray filled circle shows the s, and gray dashed lines indicate density of the time-average magnetic s is also seen from nd with Aberration of light in a relativistic jet: gamma-ray sky is dom by blazars Blazar Chapter 6 Another co ments of small-scale shall Cohen, and the discovered that in ce These are precisely th that is, whose emissi any misalignment is jets associated with c the emission – are no with the faint extend degrees or more. Thi One does not expect less they exhibit som radio sources, which the bending is exagg Observer Observer Observer Observer v = 0 0.75c 0.94c 0.98c Tchekhovskoy
24. Dark matter?
25. Unknown Known populations of γ-ray sources ? ? ?
26. 1/3 of gamma-ray sources are unknown Unknown Known populations of γ-ray sources black holes? ? ? ? Pulsars? Exotic physics: Dark matter?
27. Dark matter
28. Ωm0 = 0.3 ΩΛ0 = 0.7 Ωr0 = 8×10-5 26% 70% 4% Standard cosmological model (ΛCDM) H0 = 70 km /s /Mpc k = 0 (flat) Ω0 = 1 ✓ H H0 ◆2 = ⌦ + 1 ⌦0 a2 p = w⇢c2 ⌦ = ⌦m + ⌦rad + ⌦⇤ Friedmann equation density parameter eq. of state ¨ a a = 4⇡G 3c2 (✏ + 3p) acceleration eq.
29. Candidatos a matéria escura Áxions: partículas hipotéticas com mc2~10-5 eV Buracos negros primordiais: m ~105 Msol Fundo cósmico de neutrinos (levemente massivos) WIMPs: Weakly Massive Interacting Particles partículas não-bariônicas como fotinos, gravitinos, axinos, sneutrinos, gluinos, etc. mc2 >10 GeV
31. Dark Sector of Vermions Varks Veptons Dark charge Dark charge Vosons Vluon Voton ? ? ? ? ? ? ? Dark Dark charge Dark charged Vosons ? ? ? ?
32. Eγ = 130 GeV WIMP particles annihilate Gamma-ray photon produced mχ = 65 GeV χ χ
33. A tentative gamma-ray line from Dark Matter annihilation w/ Fermi LAT 012)007 Weniger+2012, JCAP Significance ~3-4σ Energy (GeV) 0 Energy (GeV) 60 80 100 120 140 160 180 200 220 ) σ Resid. ( -4 -2 0 2 4 Energy (GeV) Events / 5.0 GeV 0 10 20 30 40 50 60 70 = 133.0 GeV γ P7_REP_CLEAN R3 2D E = 17.8 evts sig n σ = 3.3 local s = 276.2 evts bkg n = 2.76 bkg Γ (c) Energy (GeV) 60 80 100 120 140 160 180 200 220 ) σ Resid. ( -4 -2 0 2 4 FIG. 11. Fits for a line near 130 GeV in R3: (a) at 130 GeV in the P7CLEAN data using Ackermann+13 sglobal ~1.6σ
34. Uncovering a gamma-ray excess at the Galactic Center Hooper+2014
35. Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data M. Ackermann,1 A. Albert,2 B. Anderson,3,4,* W. B. Atwood,5 L. Baldini,6,2 G. Barbiellini,7,8 D. Bastieri,9,10 K. Bechtol,11 R. Bellazzini,12 E. Bissaldi,13 R. D. Blandford,2 E. D. Bloom,2 R. Bonino,14,15 E. Bottacini,2 T. J. Brandt,16 J. Bregeon,17 P. Bruel,18 R. Buehler,1 G. A. Caliandro,2,19 R. A. Cameron,2 R. Caputo,5 M. Caragiulo,13 P. A. Caraveo,20 C. Cecchi,21,22 E. Charles,2 A. Chekhtman,23,§ J. Chiang,2 G. Chiaro,10 S. Ciprini,24,21,25 R. Claus,2 J. Cohen-Tanugi,17 J. Conrad,3,4,26 A. Cuoco,14,15 S. Cutini,24,25,21 F. D’Ammando,27,28 A. de Angelis,29 F. de Palma,13,30 R. Desiante,31,14 S. W. Digel,2 L. Di Venere,32 P. S. Drell,2 A. Drlica-Wagner,33,† R. Essig,34 C. Favuzzi,32,13 S. J. Fegan,18 E. C. Ferrara,16 W. B. Focke,2 A. Franckowiak,2 Y. Fukazawa,35 S. Funk,36 P. Fusco,32,13 F. Gargano,13 D. Gasparrini,24,25,21 N. Giglietto,32,13 F. Giordano,32,13 M. Giroletti,27 T. Glanzman,2 G. Godfrey,2 G. A. Gomez-Vargas,37,38 I. A. Grenier,39 S. Guiriec,16,40 M. Gustafsson,41 E. Hays,16 J. W. Hewitt,42 D. Horan,18 T. Jogler,2 G. Jóhannesson,43 M. Kuss,12 S. Larsson,44,4 L. Latronico,14 J. Li,45 L. Li,44,4 M. Llena Garde,3,4 F. Longo,7,8 F. Loparco,32,13 P. Lubrano,21,22 D. Malyshev,2 M. Mayer,1 M. N. Mazziotta,13 J. E. McEnery,16,46 M. Meyer,3,4 P. F. Michelson,2 T. Mizuno,47 A. A. Moiseev,48,46 M. E. Monzani,2 A. Morselli,37 S. Murgia,49 E. Nuss,17 T. Ohsugi,47 M. Orienti,27 E. Orlando,2 J. F. Ormes,50 D. Paneque,51,2 J. S. Perkins,16 M. Pesce-Rollins,12,2 F. Piron,17 G. Pivato,12 T. A. Porter,2 S. Rainò,32,13 R. Rando,9,10 M. Razzano,12 A. Reimer,52,2 O. Reimer,52,2 S. Ritz,5 M. Sánchez-Conde,4,3 A. Schulz,1 N. Sehgal,53 C. Sgrò,12 E. J. Siskind,54 F. Spada,12 G. Spandre,12 P. Spinelli,32,13 L. Strigari,55 H. Tajima,56,2 H. Takahashi,35 J. B. Thayer,2 L. Tibaldo,2 D. F. Torres,45,57 E. Troja,16,46 G. Vianello,2 M. Werner,52 B. L. Winer,58 K. S. Wood,59 M. Wood,2,‡ G. Zaharijas,60,61 and S. Zimmer3,4 PRL 115, 231301 (2015) P H Y S I C A L R E V I E W L E T T E R S week ending 4 DECEMBER 2015 Max-Planck-Institut für Physik, D-80805 München, Germany 52Institut für Astro- und Teilchenphysik and Institut für Theoretische Physik, Leopold-Franzens-Universität Innsbruck, A-6020 Innsbruck, Austria 53Physics and Astronomy Department, Stony Brook University, Stony Brook, New York 11794, USA 54NYCB Real-Time Computing Inc., Lattingtown, New York 11560-1025, USA 55Texas A&M University, Department of Physics and Astronomy, College Station, Texas 77843-4242, USA 56Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601, Japan 57Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain 58Department of Physics, Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, Ohio 43210, USA 59Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352, USA 60Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, and Università di Trieste, I-34127 Trieste, Italy 61Laboratory for Astroparticle Physics, University of Nova Gorica, Vipavska 13, SI-5000 Nova Gorica, Slovenia (Received 10 March 2015; revised manuscript received 15 July 2015; published 30 November 2015) The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new PASS8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass ≲100 GeV annihilating via quark and τ-lepton channels. DOI: 10.1103/PhysRevLett.115.231301 95.35.+d, 95.85.Pw, 98.56.Wm, 98.70.Rz
36. Indication of Gamma-Ray Emission from the Newly Discovered Dwarf Galaxy Reticulum II Alex Geringer-Sameth* and Matthew G. Walker† McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA Savvas M. Koushiappas‡ Department of Physics, Brown University, Providence, Rhode Island 02912, USA Sergey E. Koposov, Vasily Belokurov, Gabriel Torrealba, and N. Wyn Evans Institute of Astronomy, University of Cambridge, Cambridge CB3 0HA, United Kingdom (Received 8 March 2015; published 17 August 2015) We present a search for γ-ray emission from the direction of the newly discovered dwarf galaxy Reticulum II. Using Fermi-LAT Collaboration data, we detect a signal that exceeds expected backgrounds between ∼2–10 GeV and is consistent with annihilation of dark matter for particle masses less than a few ×102 GeV. Modeling the background as a Poisson process based on Fermi-LAT diffuse models, and taking into account trial factors, we detect emission with p value less than 9.8 × 10−5 (>3.7σ). An alternative, model-independent treatment of the background reduces the significance, raising the p value to 9.7 × 10−3 (2.3σ). Even in this case, however, Reticulum II has the most significant γ-ray signal of any known dwarf galaxy. If Reticulum II has a dark-matter halo that is similar to those inferred for other nearby dwarfs, the signal is consistent with the s-wave relic abundance cross section for annihilation. PRL 115, 081101 (2015) Selected for a Viewpoint in Physics P H Y S I C A L R E V I E W L E T T E R S week ending 21 AUGUST 2015
37. Multimessenger astronomy
38. The Multi-Messenger Connection: Gravitational Waves 6 GW events announced by the LIGO/VIRGO Collaboration: 5 BH- BH: GW150914, LVT151012, GW151226,GW170104, GW170814; 1 NS-NS: GW170817; BH-BH mergers are not expected to produce EM radiation. NS-NS: predicted (and confrmed) to produce EM radiation. General strategy for Fermi-LAT searches at high-energy: Automated full sky searches of transients Specifc searches in the LIGO contours The Multi-Messenger Connection: Gravitational Waves 6 GW events announced by the LIGO/VIRGO Collaboration: 5 BH- BH: GW150914, LVT151012, GW151226,GW170104, GW170814; 1 NS-NS: GW170817; BH-BH mergers are not expected to produce EM radiation. NS-NS: predicted (and confrmed) to produce EM radiation. General strategy for Fermi-LAT searches at high-energy: Automated full sky searches of transients Specifc searches in the LIGO contours Specifc followups of detected counterparts Pipelines to quick alert the community Multi messenger astronomy with gravitational waves slide: A. Dominguez
39. Abbott+2015, PRL
40. Two black holes in vacuum → Gravitational waves detected with LIGO! no EM counterpart ~20-60 Msun
41. A moment long-awaited…
42. Birth of multimessenger astronomy: GWs and EM radiation from same source
44. IceCube: Cubic-kilometer Neutrino Observatory
45. Neutrinos from accelerated protons: standard prediction from hadronic physics black hole relativistic jet accretion disk
46. IceCube Collaboration et al., Science 2018 DOI: 10.1126/ science.aat1378
48. RESEARCH ARTICLE ◥ NEUTRINO ASTROPHYSICS Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A The IceCube Collaboration, Fermi-LAT, MAGIC, AGILE, ASAS-SN, HAWC, H.E.S.S, INTEGRAL, Kanata, Kiso, Kapteyn, Liverpool Telescope, Subaru, Swift/NuSTAR, VERITAS, and VLA/17B-403 teams*† Previous detections of individual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of e290 tera–electronvolts. Its arrival direction was consistent with the location of a known g-ray blazar, TXS 0506+056, observed to be in a flaring state. An extensive multiwavelength campaign followed, ranging from radio frequencies to g-rays. These observations characterize the variability and energetics of the blazar and include the detection of TXS 0506+056 in very-high-energy g-rays. This observation of a neutrino in spatial coincidence with a g-ray–emitting blazar during an active phase suggests that blazars may be a source of high-energy neutrinos. RESEARCH Fig. 2. Fermi-LATand MAGIC observations of IceCube-170922A’s location. Sky position of IceCube-170922A in J2000 equatorial coordinates overlaying the g-ray counts from Fermi-LAT above 1 GeV (A) and the signal significance as observed by MAGIC (B) in this region. The tan square indicates the position reported in the initial alert, and the green square indicates the final best-fitting position from follow-up reconstructions (18). Gray and red curves show the 50% and 90% neutrino containment regions, respectively, including statistical and systematic errors. Fermi-LAT data are shown as a photon counts map in 9.5 years of data in units of counts per pixel, using detected photons with energy of 1 to 300 GeV in a 2° by 2° region around TXS0506+056. The map has a pixel size of 0.02° and was smoothed with a 0.02°-wide Gaussian kernel. MAGIC data are shown as signal significance for g-rays above 90 GeV. Also shown are the locations of a g-ray source observed by Fermi-LAT as given in the Fermi-LAT Third Source Catalog (3FGL) (23) and the Third Catalog of Hard Fermi-LAT Sources (3FHL) (24) source catalogs, including the identified positionally coincident 3FGL object TXS 0506+056. For Fermi-LAT catalog objects, marker sizes indicate the 95% CL positional uncertainty of the source. on July 12, 2018 cemag.org/ IceCube Collaboration et al., Science 2018 DOI: 10.1126/ science.aat1378
50. Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data M. Ackermann,1 A. Albert,2 B. Anderson,3,4,* W. B. Atwood,5 L. Baldini,6,2 G. Barbiellini,7,8 D. Bastieri,9,10 K. Bechtol,11 R. Bellazzini,12 E. Bissaldi,13 R. D. Blandford,2 E. D. Bloom,2 R. Bonino,14,15 E. Bottacini,2 T. J. Brandt,16 J. Bregeon,17 P. Bruel,18 R. Buehler,1 G. A. Caliandro,2,19 R. A. Cameron,2 R. Caputo,5 M. Caragiulo,13 P. A. Caraveo,20 C. Cecchi,21,22 E. Charles,2 A. Chekhtman,23,§ J. Chiang,2 G. Chiaro,10 S. Ciprini,24,21,25 R. Claus,2 J. Cohen-Tanugi,17 J. Conrad,3,4,26 A. Cuoco,14,15 S. Cutini,24,25,21 F. D’Ammando,27,28 A. de Angelis,29 F. de Palma,13,30 R. Desiante,31,14 S. W. Digel,2 L. Di Venere,32 P. S. Drell,2 A. Drlica-Wagner,33,† R. Essig,34 C. Favuzzi,32,13 S. J. Fegan,18 E. C. Ferrara,16 W. B. Focke,2 A. Franckowiak,2 Y. Fukazawa,35 S. Funk,36 P. Fusco,32,13 F. Gargano,13 D. Gasparrini,24,25,21 N. Giglietto,32,13 F. Giordano,32,13 M. Giroletti,27 T. Glanzman,2 G. Godfrey,2 G. A. Gomez-Vargas,37,38 I. A. Grenier,39 S. Guiriec,16,40 M. Gustafsson,41 E. Hays,16 J. W. Hewitt,42 D. Horan,18 T. Jogler,2 G. Jóhannesson,43 M. Kuss,12 S. Larsson,44,4 L. Latronico,14 J. Li,45 L. Li,44,4 M. Llena Garde,3,4 F. Longo,7,8 F. Loparco,32,13 P. Lubrano,21,22 D. Malyshev,2 M. Mayer,1 13 16,46 3,4 2 47 48,46 2 PRL 115, 231301 (2015) P H Y S I C A L R E V I E W L E T T E R S week ending 4 DECEMBER 2015 Hands-on activity
51. Quiz time! https://kahoot.it/
52. Github Twitter Web E-mail Bitbucket Facebook Group figshare rodrigo.nemmen@iag.usp.br rodrigonemmen.com @nemmen rsnemmen facebook.com/rodrigonemmen nemmen blackholegroup.org bit.ly/2fax2cT
53. Director’s cut (cf separate file)