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Neutron Star Powered Nebulae

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This is the presentation I gave when defending my Ph.D thesis at SLAC. The title of my defense was "Neutron Star Powered Nebulae: a New View on Pulsar Wind Nebulae with the Fermi Gamma-ray Space Telescope".

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Neutron Star Powered Nebulae

  1. 1. Neutron Star Powered Nebulae: a NewView on Pulsar Wind Nebulae with the Fermi Gamma-ray Space Telescope Joshua Lande @joshualande
  2. 2. Please ask questions!!
  3. 3. Why do we do astronomy?
  4. 4. Nabta Playa 5th century BC
  5. 5. Liberal Arts The Trivium •grammar •logic •rhetoric The Quadrivium •arithmetic •geometry •music •astronomy
  6. 6. Multiwavelenth astronomy
  7. 7. We can study astronomy across the electromagnetic spectrum
  8. 8. William Herschel 1800 Infrared Astronomy Radio-wave Astronomy Karl Jansky 1933
  9. 9. ultraviolet - 1946 X-ray - 1949
  10. 10. Gamma-ray Astrophysics
  11. 11. Explorer XI
  12. 12. OSO-3
  13. 13. OSO-3: 621 gamma-rays
  14. 14. COS-B SAS-2
  15. 15. Cos-B Skymap
  16. 16. EGRET
  17. 17. EGRET Sky Map
  18. 18. The Fermi Gamma-ray Space Telescope
  19. 19. The Fermi Gamma-ray Space Telescope 20 MeV to >300 GeV
  20. 20. The Large Area Telescope Tracker Layers Calorimeter Layers Anti-Coincidence Detector (surrounding) Large Area Telescope (LAT) Fermi Gamma-ray Space Telescope photon positron electron
  21. 21. Angular Resolution of the LAT
  22. 22. Blastoff!
  23. 23. The Gamma-ray Sky
  24. 24. Very High Energy Astrophysics
  25. 25. Very High Energy Astrophysics
  26. 26. The High Energy Stereoscopic System (H.E.S.S)
  27. 27. Fermi ~ 20 MeV to 300 GeV Air Cherenkov Detectors ~100 GeV and ~30 TeV
  28. 28. Astrophysical Sources of Gamma-rays
  29. 29. Many sources of gamma-rays
  30. 30. The 2FGL Catalog No association Possible association with SNR or PWN AGN Pulsar Globular cluster Starburst Gal PWN HMB Galaxy SNR Nova
  31. 31. Pulsars, Supernova Remnants, and PWNe are connected through a simple picture Gaensler & Slane (2006)
  32. 32. Supernova are new stars that appear in the sky. ~L|F Left: SN 1054 (Crab Nebula)
  33. 33. 7 supernova visible by the human eye in ~2,000 years. Right: SN 1572 (Tycho’s SN)
  34. 34. Pulsars are the remaining core of neutron Stars
  35. 35. Pulsars have periodic emission
  36. 36. Pulsar Wind Nebula (PWN) are observed to surround pulsars
  37. 37. Energy Spectrum of the Crab Nebula
  38. 38. Radiation Processes in PWN
  39. 39. Gamma-ray Observations
  40. 40. How to identify Gamma-ray Pulsars? Vela
  41. 41. Pulsar Phase 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 Events/BinWidth 0 0.2 0.4 0.6 0.8 1 6 10× 0.12 0.13 0.14 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 6 10× 0.54 0.56 0.58 0.6 0.7 0.8 0.9 1 6 10× Pulsar light curve Vela
  42. 42. Energy (GeV) −1 10 1 10 )−1 s−2 dN/dE(ergcm2 E −10 10 −9 10 Energy Band Fits Maximum Llikelhood Model Pulsar Energy Spectrum Vela
  43. 43. 117 Gamma-ray Pulsars in the Second Pulsar Catalog
  44. 44. Gamma-ray PWN Crab Nebula Vela X Abdo et al 2010 Abdo et al 2010
  45. 45. Crab Nebula :26 (8pp), 2012 April 10 Buehler et al. Pulsar phase 0.4 0.6 0.8 Pulsar phase 0.4 0.6 0.8 Figure 2. Spectral energy distribution for the Crab Nebula averaged over the first 33 months of Fermi observations. The axis on the right side indicates the 1260 ABDO ET AL. Vol. 708 Figure 4. Counts maps (arbitrary units) presenting the pulsed (top row) and nebular (bottom row) emission, in three energy bands. Each panel spans 15◦ × 15◦ in equatorial coordinates and is centered on the pulsar radio position. Left: 100 MeV < E < 300 MeV; middle: 300 MeV < E < 1 GeV; right: E > 1 GeV. (A color version of this figure is available in the online journal.) Abdo et al 2010 Abdo et al 2010
  46. 46. How do we know it is a PWN? aharonian et al 2005 •PWN should have rising spectrum •PWN can be extended •Clear identification difficult: •X-ray PWN often much smaller •Pulsars can be offset •other possible counterparts •Pulsar energetics? •PWN candidate vs clear detection? •Energy dependent morphology •Matching X-ray to Gamma-ray mormorphology? L26 F. A. Aharonian et al.: The association of HESS J1825–137 with G 18.0–0.7 1. Introduction PSR B1823–13 (also known as PSR J1826–1334) is a 101 ms evolved pulsar with a spin-down age of T = 2.1 × 104 years (Clifton et al. 1992) and in these properties very similar to the Vela pulsar. It is located at a distance of d = 3.9 ± 0.4 kpc (Cordes & Lazio 2002) and ROSAT observations of this source with limited photon statistics revealed a compact core, as well as an extended diffuse nebula of size ∼5 south-west of the pul- sar (Finley et al. 1998). High resolution XMM-Newton obser- vations of the pulsar region confirmed this asymmetric shape and size of the diffuse nebula, which was hence given the name G 18.0–0.7 (Gaensler et al. 2003). For the compact core with extent RCN ∼ 30 (CN: compact nebula) immediately sur- rounding the pulsar, a photon index of ΓCN = 1.6+0.1 −0.2 was mea- sured with a luminosity of LCN ∼ 9d2 4 × 1032 erg s−1 in the 0.5 to 10 keV range for a distance of 4d4 kpc. The corresponding pulsar wind shock radius is Rs ≤ 15 = 0.3d4 pc. The com- pact core is embedded in a region of extended diffuse emission which is clearly one-sided, revealing a structure south of the pulsar, with an extension of REN ∼ 5 , (EN: extended nebula) whereas the ∼4 east-west extension is symmetric around the north-south axis. The spectrum of this extended component is -5 0 5 10 15 20 25 30 -14 -13.5 18h24m18h26m18h28m PSR B1823-13 RA (hours) )°Dec ( 3EG J1826-1302 PSF HESS J1825-137 Fig. 1. Excess map of the region close to PSRB1823–13 (marked with a triangle) with uncorrelated bins. The best fit centroid of the γ-ray excess is shown with error bars. The black dotted circle shows the LettertotheEditor
  47. 47. Many TeV Pulsar Wind Nebula •Many PWN detected at TeV energies •Limited Background, •Improved sensitivity •No Pulsar signal •32 TeV PWN
  48. 48. Harder at Gamma-ray energies •Limited Angular Resolution •Large Galactic Background •Non-linear Detector response •Emission could be from the pulsar. •Crowded gamma-ray sky
  49. 49. How do we search for new gamma-ray emitting PWN? Association with LAT- detected Association with TeV PWN Spatial Morphology
  50. 50. Extended Fermi Sources
  51. 51. You can study extended LAT sources using maximum-likelihood analysis ering events). The likelihood function d emission: L = Y j ✓ kj j e ✓j kj! . tion and energy bins, kj are the counts ts predicted in the same bin. re computed by integrating the di↵ere ~⌦0 at a time t0 . The dispersion is written as P(E0 , t0 , ~⌦0 |E, t, ~⌦). It repre probability and is therefore normalized such that Z Z Z dEd⌦dtP(E0 , t0 , ~⌦0 |E, t, ~⌦) = 1 Therefore, P(E0 , t0 , ~⌦0 |E, t, ~⌦) has units of 1/energy/SA/time The convolution of the model a source with the IRFs produces the expec ferential counts (counts per unit energy/time/SA) that are reconstructed to energy E0 at a position ~⌦0 and at a time t0 : ⌧(E0 , ~⌦0 , t0 | ) = Z Z Z dE d⌦ dt F(E, t, ~⌦| )✏(E, t, ~⌦)P(E0 , t0 , ~⌦0 |E, t, ~⌦) Here, this integral is performed over all energies, SAs, and times. For LAT analysis, we conventionally make the simplifying assumption t Here, j refers to a sum over position and energy bins, kj a bin j, and ✓j are the model counts predicted in the same b The model counts in bin j are computed by integrat counts over the bin: ✓ij = Z j dE d⌦ dt ⌧(E, ~⌦, t| i). Here, j represents the integral over the jth position/energ source, i refers to the parameters defining the ith source, a 1 0 plicated hypothesis and H0 th mpare the likelihood when ass ended spatial model: TSext = 2 log(Lext/Lps). n be written as: L = L( ). ysis, one typically fits parameters of a model ction of the parameters of the model. max = arg maxL( )
  52. 52. 0◦ 0.◦ 1 0.◦ 2 0.◦ 3 0.◦ 4 0.◦ 5 0.◦ 6 Extension 10000 10200 10400 10600 10800 11000 11200TestStatistic (a) 102 103 104 105 Energy (MeV) 0 50 100 150 200 TSext (b) 0.0 0.1 0.2 0.3 0.4 0.5 ∆θ2 ([deg]2 ) 101 102 103 Counts (c) Disk Point Counts (d) 2◦ 3◦ b 188◦ 189◦ l 0 500 1000 1500 2000 2500 3000 3500 counts[deg]−2 Extended Source IC 443
  53. 53. Search each source in 2FGL for extension
  54. 54. IC 443 Puppis A W44 MSH 15−52 W51C W28 SMC Gamma Cygni Vela X Cygnus Loop Vela Jr. LMC RX J1713.7−3946 HESS J1825−127 W30 Centarus A New Extended Sources
  55. 55. 0 1b 2526 l 0 25 50 75 100 125 150 175 200 225 counts/[deg]2 HESS J1837-069
  56. 56. 1 000 0 300 0 000 0 300 b 331 300 332 000 332 300 333 000 l 0 30 60 90 120 150 180 210 240 270 counts/[deg]2 HESS J1616−508
  57. 57. 1 0 1 b 336337 l 0 30 60 90 120 150 180 210 240 270 counts/[deg]2 HESS J1632-478
  58. 58. 10−6 10−5 E2 dN/dE(MeVcm−2 s−1 ) (a) HESS J1616−508 (b) HESS J1614−518 LAT H.E.S.S 104 105 106 107 Energy (MeV) 10−6 10−5 E2 dN/dE(MeVcm−2 s−1 ) (c) HESS J1632−478 104 105 106 107 Energy (MeV) (d) HESS J1837−069
  59. 59. PWN Search in the Off-Peak
  60. 60. Search LAT-detected pulsars for PWN
  61. 61. 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 500 600 700 800 Counts 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 0.0 0.2 0.4 0.6 0.8 1.0 0 50 100 150 200 250 300 350 Counts 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 500 0.0 0.2 0.4 0.6 0.8 1.0 Phase 0 100 200 300 400 500 600 700 Counts 0.0 0.2 0.4 0.6 0.8 1.0 Phase 0 5 10 15 20 25 30 35 We can define the off-peak region using a Bayesian Block decomposition of the pulsar light curve
  62. 62. Is it a pulsar or a PWN?Grondin et al. Energy [MeV] 3 10 4 10 5 10 6 10 7 10 ]-1s-2 dN/dE[ergcm2 E -12 10 -11 10 -10 10 pectral energy distribution of HESS J1825−137 in gamma-rays. The LAT spectral points (in red) are obtained using the maximum likelihood described in section 4.2 in 6 logarithmically-spaced energy bins. The statistical errors are shown in red, while the black lines take into account both nd systematic errors as discussed in section 4.2. The red solid line presents the result obtained by fitting a power-law to the data in the 1 – 100 GeV using a maximum likelihood fit. A 95 % C.L. upper limit is computed when the statistical significance is lower than 3 σ. The H.E.S.S. results are blue (Aharonian et al. 2006). pulsar, we fix the initial spin period at 10 ms and ex at 2.5, yielding an age of 26 kyr for the sys- simple injection spectrum slightly underestimates ata but the overall fit is still reasonable. For the of 26 kyr, we require a power-law index of 1.9, 57 TeV and a magnetic field of 4 µG. The corre- sult is presented in Figure 4 (Top). option to fit the multi-wavelength data is adopting tic Maxwellian plus power-law tail electron spec- sed by Spitkovsky (2008). For this injection spec- sume a bulk gamma-factor (γ0) for the PWN wind f the termination shock. At the termination shock t pressure balances the wind pressure, fully ther- e wind; in this case the downstream post-shock = (γ0 − 1)/2. One could also interpret this as e temperature kT of mec2 (γ0 − 1)/2. Per the of Spitkovsky (2008), a power-law tail begins at mec2 γ0, and suffers an exponential cutoff at some The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the de- velopment and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat `a l’Energie Atomique and the Centre National de la Recherche Scientifique / Institut Na- tional de Physique Nucl´eaire et de Physique des Particules in France, the Agenzia Spaziale Italiana, the Istituto Nazionale di Fisica Nucleare, and the Istituto Nazionale di Astrofisica in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation and the Swedish National Space Board in Sweden. Additional support for science analysis during the opera- tions phase from the following agencies is also gratefully acknowledged: the Instituto Nazionale di Astrofisica in Italy and the Centre National d’´Etudes Spatiales in France. The Nanc¸ay Radio Observatory is operated by the Paris Observatory, associ- ated with the French Centre National de la Recherche Scientifique (CNRS). The Lovell Telescope is owned and operated by the University of Manchester as part of the Jodrell Bank Centre for Astrophysics with support from the Science and Technology Facilities Council of the United Kingdom. The Parkes radio telescope is part of the Australia Telescope which is funded – 37 – Energy (MeV) 2 10 3 10 4 10 ]-1 s-2 dN/dE[ergcm2 E -11 10 -10 10 1 ]-1 s-2 dN/dE[ergcm2 E -12 10 -11 10 Energy (MeV) 2 10 3 10 10 ]-1 s-2 dN/dE[ergcm2 E -12 10 -11 10 4 Grondin et al. HESS J1825-137 (Grondin et al 2011) PSR J2021+4026 Ackermann et al 2010 HESS J1825-137 (Grondin et al 2011) Spectral Shape: • Pulsars are cutoff • PWN rising spectrum Morphology • Pulsars are point sources • PWN could be extended
  63. 63. 10 13 10 12 10 11 10 10 10 9 10 13 10 12 10 11 10 10 E2 dN/dE(ergcm2 s1 ) 10 13 10 12 10 11 10 10 10 9 10 1 100 101 102 Energy (GeV) 10 1 100 101 102 Energy (GeV) We performed a spectral and spatial analysis of each off- peak region
  64. 64. Off-peak Sources •116 pulsars tested •34 significant sources •9 are clearly pulsar emission •4 are pulsar wind nebula •1 new pulsar wind nebula
  65. 65. 3C 58 is associated and PSR J0205+6449 Coincident with SNR 3C 58 and SN 1181
  66. 66. Search for TeV PWN
  67. 67. HESS J1303-613 1 0 1 b 262728 l 0 20 40 60 80 100 120 140 160 180 counts/[deg]2 HESS J1841-055 1 0 b 292293 l 0 10 20 30 40 50 60 70 80 90 counts/[deg]2 HESS J1119-614 HESS J1356-645 0 1 b 313314 l 0 25 50 75 100 125 150 175 200 225 counts/[deg]2 HESS J1420-607
  68. 68. PWN Detected by LAT •Before Fermi, 1 PWN Detected (Crab) •Now, 17 PWN candidates •5 clearly associated with PWN •12 have less certain identification.
  69. 69. PWN Population Study
  70. 70. 102 103 104 105 106 107 108 109 1010 1011 ⌧C [years] 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 ˙E[ergs1 ] LAT Detects PWN from young and highly- energetic pulsars
  71. 71. 1034 1035 1036 1037 1038 1039 ˙E 1032 1033 1034 1035 1036 LGeV The PWN Luminosity is small compared to the pulsar’s spin-down energy
  72. 72. 1033 1034 1035 1036 LGeV(ergs1 ) 103 104 105 Age (yr) 100 101 102 LGeV/LTeV 1035 1036 1037 1038 1039 ˙E (erg s 1 ) LGeV and LGeV/LTeV not correlated with age and spin-down energy
  73. 73. 1031 1032 1033 1034 1035 1036 1037LX(ergs1 ) 103 104 105 Age (yr) 10 2 10 1 100 101 102 103 104 LGeV/LX 1035 1036 1037 1038 1039 ˙E (erg s 1 ) LGeV/LX correlates with the age and spin- down energy
  74. 74. The lifetime of gamma-ray emitting electrons is longer than of X-ray emitting electrons.EVOLUTION OF THE γ - AND X-RAY LUMINOSITIES OF PWNe 102 103 104 105 Time (yr) 0.01 0.10 1.00 Normalizednumberofparticles nγnX tcγtcX 10-1 100 101 102 103 104 Rationγ/nX nγ /nX Mattana et al 2009
  75. 75. Conclusions
  76. 76. Acknowledgments
  77. 77. Stanford Physics
  78. 78. The LAT Collaboration
  79. 79. Big thanks to my defense committee!
  80. 80. The Funk Group
  81. 81. Thanks to my family!
  82. 82. Thanks to the administrators!
  83. 83. Finally, thanks for coming!
  84. 84. Questions?

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