1 / 49

Gamma-ray Evidence for UHECR Acceleration by GRBs and AGNs

HiRes Collaboration 2008. Auger Collaboration 2008, 2209. Gamma-ray Evidence for UHECR Acceleration by GRBs and AGNs. Department of Physics Purdue University January 31, 2011. Chuck Dermer Naval Research Laboratory Washington, DC USA charles.dermer@nrl.navy.mil. GZK radius MFP

carol
Download Presentation

Gamma-ray Evidence for UHECR Acceleration by GRBs and AGNs

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HiRes Collaboration 2008 Auger Collaboration 2008, 2209 Gamma-ray Evidence for UHECR Acceleration by GRBs and AGNs Department of Physics Purdue University January 31, 2011 Chuck Dermer Naval Research Laboratory Washington, DC USA charles.dermer@nrl.navy.mil • GZK radius • MFP • Horizon Dermer Purdue University Seminar 31 Jan 2011

  2. Outline 1. Viable UHECR source candidates • Sources are extragalactic • Acceleration mechanism to ultra-high energies Acceleration region smaller than Larmor radius (Hillas condition) • Adequate energy production rate within GZK volume • Sources within GZK radius • UHECRs can escape from acceleration region 2. Spectral fitting of blazars and radio galaxies: Evidence for UHECRs? 3. IGMF Measurements from GeV-TeV Observations 4. UHECR signatures in BL Lacs and the EBL? Dermer Purdue University Seminar 31 Jan 2011

  3. 1. Viable UHECR Source Candidates • GRBs • AGNs • Magnetars • Structure formation shocks in clusters of galaxies • Hot spots in radio galaxies • Galactic sources …. Dermer Purdue University Seminar 31 Jan 2011

  4. 1. Sources are Extragalactic 58 events: July, 2009 (with Swift-BAT AGN density map) Auger collaboration: 69 events 31 Dec 2009 (arXiv:1009.1855) d/2 d/2 27 events as of November 2007 rL (14 events) Dermer Purdue University Seminar 31 Jan 2011

  5. 2. Mechanism to accelerate to ultra-high energies external shocks or colliding shells Hillas condition: rL′ = E′/QB′ < R′ Relativistic Shock Hydrodynamics Requirement to accelerate to ultra-high energies by Fermi processes: Requirements for UHECR acceleration: 1. Large G contrast 2. Rapid variability 3. Strong forward shock Dermer & Razzaque (2010) Dermer Purdue University Seminar 31 Jan 2011

  6. L  G diagram • Sources with jet Lorentz factor G must have jet power L exceeding heavy solid and dot-dashed curves to accelerate p and Fe respectively, to E = 1020 eV • Bulk Lorentz factor G from gg opacity arguments • Eg • Cospatial assumption • tvar • GRBs can easily accelerate p and Fe to >1020 eV • Blazars can accelerate Fe to >1020 eV Dermer & Razzaque (2010) Dermer Purdue University Seminar 31 Jan 2011

  7. dE/dtdV = 4×1044 erg Gpc-3 yr-1 3. Energy Production Rate within GZK Volume • uUHECR/tGZK ~ 10-21 erg cm-3/(100 Mpc/c) ~1044 erg Mpc-3 yr-1 • Inject 2.2 spectrum of UHECR protons to E > 1020 eV • Injection rate density determined by star formation activity • GZK cutoff and ankle from photohadronic processes Hopkins & Beacom 2006 Requires luminosity density > 4×1044 erg Mpc-3 yr-1 ~ Dermer Purdue University Seminar 31 Jan 2011

  8. Luminosity Density from Observations (Nonthermal) g-ray luminosity density (energy/ time/ volume) assumed to represent power in UHECRs • Consider M87 at 16 Mpc: 5x1041 erg s-1 (> 100 MeV)  ℓ  1045 erg Mpc-3 yr-1 • Cen A at 3.5 Mpc and 4x smaller luminosity  ℓ  1046 erg Mpc-3 yr-1 • Per A is 200 x larger but at 75.3 Mpc  ℓ  2x1045 erg Mpc-3 yr-1 • Compare: Mean GRB flux BATSE data for long GRBs (LAT only) Dermer Purdue University Seminar 31 Jan 2011

  9. Luminosity Density of UHECR Candidates from Fermi Data Fermi data shows nonthermal g-ray luminosity density exceeds amount needed for UHECRs GRBs have adequate energy production rate only if baryon loading large UHECR requirements GRB observations Dermer & Razzaque (2010) Dermer Purdue University Seminar 31 Jan 2011

  10. 4. Sources within the GZK Radius • Several FR1 radio galaxies: Cen A, M87, NGC 1275, NGC 6251 •  BL Lac objects near the edge of the GZK radius: Mrk 421, Mrk 501 • No FR2 radio galaxies within the GZK radius (closest is 3C 111) Cygnus A and Pictor A • Nearby FR2 and BLRG: • 3C 111 at z = 0.0486 (d  210 Mpc) Lg = 1043.87 erg s-1  ℓ44 0.6 • Pictor A at z = 0.0351 (d 150 Mpc) 43.25Lg = 1043.25 erg s-1  ℓ44 0.4 • (3C 120 at z = 0.033 (d  140 Mpc) Lg = 1043.49 erg s-1  ℓ44 0.9) • Deflection by lobes of radio galaxies (cf. Cen A) • Deflection of 1020E20 eV particles by Intergalactic Magnetic Field (IGMF) BIGMF = 10-15B-15 G Arrival directions of UHECRs correlated with Fermi LAT AGNs: Nemmen et al. (2010) Dermer Purdue University Seminar 31 Jan 2011

  11. 5. UHECR escape from acceleration region Depends on composition • If p-dominated, claimed by HiRes • If Fe-dominated, claimed by Auger (at  4×1019 eV) Neutral beam model (Atoyan & Dermer 2003) Impulsive production makes cosmic ray shock Acceleration and escape from source region without photodisintegration Dermer Purdue University Seminar 31 Jan 2011

  12. 2. UHECR Signatures in Blazar Source Spectra? Mrk 501 Abdo et al. (2011) Dermer Purdue University Seminar 31 Jan 2011

  13. Synchrotron/SSC Fit to Mrk 501 B = 0.015 G, R = 1.3×1017 cm, δ = 12, ηe= 56 Lj 1044 erg s-1 Dermer Purdue University Seminar 31 Jan 2011

  14. Synchrotron/SSC Fit to Swift, Fermi, VERITAS data of Mrk 501 Acciari et al. (2011) Dermer Purdue University Seminar 31 Jan 2011

  15. UHECR Signatures in Mrk 421? Abdo et al. (2011), submitted Dermer Purdue University Seminar 31 Jan 2011

  16. Mrk 421: Leptonic and Hadronic Model Fits Red curve: B = 0.038 G, R = 5.2×1016 cm, δ = 21 B = 50 G, R = 4×1014 cm, δ = 12 Lj 4.5x1044 erg s-1 Lj 1.3x1044 erg s-1 Dermer Purdue University Seminar 31 Jan 2011

  17. gg opacity and Gmin for PKS 2155-304 Lower EBL • Radio galaxy core emission well fit by sync./SSC model with d  G  few • The d-unification problem -- Decelerating Jet Model (Georganopoulos & Kazanas 2003) -- Spine and Sheath Model (Ghisellini et al. 2005) -- Colliding Shell Model Standard one-zone synchrotron/SSC model (g′min = 100 ) Doppler factor d >> 100 during flaring episodes Dermer Purdue University Seminar 31 Jan 2011

  18. g rays INTERNAL SHOCK Temporal Variability >RS G2 G1 • Colliding Shell Solution: • Variability • Unification • Light curves • UHECR acceleration RS >RS Size scale in stationary frame: DR > RS Size scale in comoving frame: DR = GDR > GRS (Lorentz contracted to size R in stationary frame) tvar > DR/c > GRS/c tvar = tvar /G RS/c Can small-opening angle colliding shells avoid this problem? Dermer Purdue University Seminar 31 Jan 2011

  19. 3. IGMF Measurements from GeV-TeV Observations Pair halos (Aharonian, Coppi, & Völk 1994) Temporal delay and intergalactic Magnetic Field (IGMF) (Plaga 1995) TeV/GeV Spectral constraints on IGMF (d’Avezac et al. 2007; Neronov & Semikoz 2009; Neronov & Vovk 2010; Tavecchio et al. 2010)  lower limit to IGMF Angular extent of halos around blazars (Elyiv et al. 2009, Ando & Kusenko 2010) Halo extent at GeV energies  measurement of IGMF Magnetic fields deflect trajectories of UHECR ions; lepton secondaries of gge+e EBL B e+ g e- CMBR Dermer Purdue University Seminar 31 Jan 2011

  20. IGMF coherence length lcoh volume filling factor Magnetic fields and structure formation Magnetic fields in thick disk of Milky Way: ~3mG (Lyne and Smith 1989) Halo of the Galaxy: ~0.1 mG – several mG? Intergalactic space: << 10 nG / Z lcoh smaller than horizon size, larger than dissipation scale Limits on IGMF and Correlation Length Inflation Recombination IES 0229+200 Electroweak QCD IES 0347-121 (see Neronov & Semikoz 2009 for more detail and references) Neronov & Vovk (2010)

  21. Limits on IGMF from Spectra Neronov & Vovk (2010) z =0.14 z =0.185 z =0.186 Abdo et al. 2009, ApJ, 707, 1310

  22. Spectral Model of Halo Emission 1ES 0229+200 z =0.14 Tavecchio et al. (2010a) Cooling spectrum nFn n1/2 Compton-scattered spectrum nFn n3/2 Isotropized spectrum nFn n1/2 Neronov and Vovk and Tavecchio et al. assume persistent TeV blazar activity Tavecchio et al. (2010b)

  23. TeV radiation from Blazars Synchrotron/SSC modeling: Tavecchio et al. 2010c Extended jet with IC-CMBR Böttcher, Dermer, Finke 2008 PKS 2155-304, Mrk 501 How to make nonvariable blazar TeV radiation? Are blazars variable? g CMB e+ qj e1 e- z  0.2  d  800 Mpc 1 TeV photong 106 g2eCMB~ 500 MeV lgg ~ 200 Mpc 10 TeV photong 107 g2eCMB~ 50 GeV lgg ~ 75 Mpc 100 TeV photong 108 g2eCMB~ 5 TeV lgg ~ 3 Mpc Model of Finke et al. (2010)

  24. HESS data: Aharonian et al. (2007) VERITAS data: Perkins (2010) Model vs. Data Fermi GeV Data (Upper limits) 2008 Aug 4 – 2010 Sep 5 10o ROI <105o zenith angle P6_v3_diffuse 1FGL sources HESS and VERITAS TeV Data TeV source on for indefinitely long times Jet opening angle qbeam = 0.1 Different magnetic fields, EBL Spectral “shoulder” at ~1 GeV

  25. Model vs. Data for Different Engine Lifetimes B = 10-19 G lcoh = 1 Mpc Time-dependent solution given by AGN engine timescale B = 10-18 G lcoh = 1 Mpc

  26. 4. UHECR signatures in BL Lacs and the EBL Techinques for inferring EBL from GeV and TeV observations of BL Lacs: 1. Minimum spectral index argument 2. Extension of GeV spectrum into TeV range 3. Assumption about smoothness of TeV spectrum

  27. z = 0.047 z = 0.044 z = 0.129 z = 0.139 z = 0.186 z = 0.188 z = 0.44 z = 0.538 Finke et al. (2010)

  28. z = 0.047 z = 0.044 z = 0.129 z = 0.139 z = 0.186 z = 0.188 variable z = 0.44 z = 0.538

  29. Invalid > 10 TeV

  30. variable

  31. variable

  32. Invalid > 10 TeV

  33. dppgn = 41.6 381 687 917 1150 Mpc

  34. Evidence of UHECRs? • New component could be leptonic or hadronic • Must explain dependence of break energy on z Böttcher et al. 2008: Leptonic Model for 1ES 1101-232

  35. Conclusions • BL Lacs/FR1 radio galaxies preferred over GRBs as the sources of UHECRs • But UHECR signatures in multiwavelength BL Lac spectra lacking • Colliding shell model may explain short timescale variability in blazars, other problems in blazar physics • Relaxing assumption about BL Lac variability gives BIGMF >~ 3x10-19 G • Upturns in deabsorbed TeV BL Lac spectra due to extra (hadronic) component?

  36. Implications • UHECR-induced photopair spectral component made by UHECR protons accelerated by TeV blazars (Essey & Kusenko 2010; Essey, Kalashev, Kusenko, Beacom 2010) • ACTA/Next • HESS calibration ASTRO-2010 Recent coming of age of TeV astronomy, e.g. VERITAS • Large facility would provide order-of-magnitude leap in capability for studying black holes, supernova remnants, dark matter, pulsars, and binary stars • Two projects, the European Cherenkov Telescope Array (CTA) and the U.S. Advanced Gamma-ray Imaging System (AGIS) proposed • AGIS cost estimate: $400M. Technical risk: medium-low • RECOMMEND AGIS team should collaborate as a minor partner with European CTA team, with budget of ~ $100M over decade, shared among NSF-Physics, NSF Astronomy, and DOE

  37. Cascade spectral formation Time delay lgg ~ 100 Mpc, d ~ 600 – 800 Mpc Larmor radius Thomson length ~

  38. Semi-analytic Model of Cascade Pair injection from EBL absorption Compton (Thomson) spectrum from cooling electrons kinematic term cascade g(Dt): time for electrons to cool to g during activity time Dt of central engine g at which electrons are deflected out of beam

  39. Dermer, Cavadini, Razzaque, Finke, Lott 2010

  40. Model vs. Data for Parameters of Ando & Kusenko model Ando & Kusenko (2010; 1005.1924) ~30 halos in stacked data of 170 hard-spectrum Fermi blazars  BIGMF~10-15 G (lcoh/kpc)-1/2 Inconsistent with observations of 1ES 0229+200

  41. Dermer Purdue University Seminar 31 Jan 2011

  42. Scorecard: UHECR Sources: GRBs Blazars • Sources are extragalactic • Can accelerate to ultra-high energies: p Fe 3. Adequate energy production rate within GZK volume • Sources within GZK radius • UHECR escape Depends on composition Other sources? Dermer Purdue University Seminar 31 Jan 2011

  43. FR1/2: radio power/morphology correlation; dividing line at  4×1040 ergs s-1(1025 W/Hz-sr at 178 MHz) Radio Galaxies and Blazars Cygnus A 3C 279 BL Lacs vs. FSRQs: EW < 5 Å Ca H-K break < 0.4 (lmax −lmin)/lmax > 1.7 FR2  FSRQ Mrk 501, z = 0.034 3C 279, z = 0.538 FR1  BL Lac 3C 296 W Comae Blazar Unification: Padovani & Urry (1995) Dermer Purdue University Seminar 31 Jan 2011

  44. BL Lac and FSRQ: definition • classify an object as a BL Lac if the equivalent width (EW) of the strongest optical emission line is < 5 Å, e.g., [O II] l3727 and [O III] l5007 classification of higher-redshift sources will preferentially use lines at shorter wavelengths (e.g., Lya l1216 and C IV l1549) than for low-redshift sources (e.g., Mg II l2798 and Ha l6563). • a Ca II H/K break ratio C < 0.4, • Wavelength coverage satisfies (lmax −lmin)/lmax > 1.7 so that at least one strong emission line would have been detected if it were present. • Sources for which no optical spectrum or of insufficient quality to determine the optical classification are listed as “unknown type” 3C 279 Dermer Purdue University Seminar 31 Jan 2011

  45. Dermer Purdue University Seminar 31 Jan 2011

More Related