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Paolo Coppi Yale University

X-Ray Follow-ups of GLAST AGN (Blazars)?. ?. Paolo Coppi Yale University. P. Coppi, Yale. Suzaku, SWIFT, RXTE, Astro-SAT, EXIST?. GLAST. CGRO/EGRET and the “GeV” Blazars. Unified Blazar Scheme?. [but with jet pointed at you]. Fossati?. Donato et al. 2002, Fossati et al. 1998.

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Paolo Coppi Yale University

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  1. X-Ray Follow-ups of GLAST AGN (Blazars)? ? Paolo Coppi Yale University P. Coppi, Yale Suzaku, SWIFT, RXTE, Astro-SAT, EXIST? GLAST

  2. CGRO/EGRET and the “GeV” Blazars Unified Blazar Scheme? [but with jet pointed at you] Fossati? Donato et al. 2002, Fossati et al. 1998

  3. PKS 2155-304: multiwavelength coverage of flares … Uh, oh…. SWIFT?? Foschini et al. 2007 (astro-ph/07010868)

  4. When (external) photon field dominates energy density, be careful if Klein-Nishina effects important. Spectral features such as “bumps” and break energies, alpha_x < 0.5! Interpretation not as obvious as in standard models! Can get spectral Index harderthan 0.5! ERC, UV blackbody seeds EGRETblazars? [~MeV] Moderski et al. 2005

  5. Hadronic models: generic energetics/time variability problems. • External photons can help photo-meson production cooling rate … • But need to be near core of AGN => high optical depth for gamma-rays! • => proton-initiated cascade! • Generically get • too many X/soft • gamma-rays • if not careful! Need simultaneous X-ray coverage!

  6. Summary Origin of alpha_x < 0.5 in EGRET blazars never resolved (and seenin more blazars than EGRET ones) – “slow cooling” interpretation has problems during flares. Watch out for Klein-Nishina effects! (alpha_x< 0.5, esync,peak -eIC,peakmapping messed up, x-ray bump does not imply new e- component) Simultaneous X-ray luminosity/spectrum also constrains cascade/hadronicmodels. Need X-rays! [Were guaranteed on EGRET, but not on GLAST. GBM?] Question for organizers: what X-ray TOO programs are already in place? (TeV community routinely applies for these every cycle.)

  7. Hadronic vs. Electronic models of TeV Blazars SSC or external Compton – currently most favoured models: • easy to accelerate electrons to TeV energies • easy to produce synchrotron and IC gamma-rays recent results require more sophisticated leptonic models Hadronic Models: • protons interacting with ambient plasmaneutrinos very slow process: • protons interacting with photon fieldsneutrinos* low efficiency + severe absorption of TeV g-rays • proton synchrotronno neutrinos very large magnetic fieldB=100 G+ accelaration ratec/rg “extreme accelerator“ (of EHE CRs) Poynting flux dominated flow unlikely *detectable neutrinos from EGRET AGN but not from TeV blazars F. Aharonian

  8. Blazar Emission Mechanisms: Idealized vs. Real Life (Buckley, Science, 1998) “Zone of Avoidance” forpair jet -- Dark Energy!

  9. GeV Blazar Models & Complications… Which photon field(s) does jet interact with??? Boettcher et al. 2001 3C279 Seed photons: IR from dust vs. Blazejowski et al. 2000 Beamed from behind, reduced efficiency?

  10. Process(es) directly responsible for observed X-ray/g-ray emission? lowest order, most “efficient” A Generic VHE Source …. Multiwavelength observations very powerful/critical! E.g., if have synchrotron/IC model LIC/Lsyn=UB/Urad, constrain B if know Urad. Also, correlated IC/synch. spectra! IC or p0

  11. Numerical simulations for 3C 279. Spada et al. 2001

  12. The “ Boring” TeV Blazars

  13. The potential advantage of TeV blazars… they are much simpler? Internal, self-consistently generated photon field… Testable predictions! Suzaku/ EXIT HESS VERITAS MAGIC CANGAROO SSC model Coppi & Aharonian 1999 [N.B. Klein-Nishina effects important!]

  14. TeV blazar (Mkn 501-like) case? [“flares”=varying electron acceleration luminosity]

  15. Christmas Tree/Internal Shock Model … clearly not right for some objects Mrk 501 X-TeV correlation STABLE over 3+ months! Linear Axes! Steady X-Ray Component?? Key – 3 keV flux tracks TeV flux relatively poorly N.B. June 1997 data (after main flaring) included!

  16. O.K. So you can explain individual spectrum, but what about the variability data? Vary source luminosity Vary E_max… Krawczysnki, Coppi, & Aharonian 2002

  17. Oops!! -- 1ES1959 May-Aug 2002 Multiple Emission Components! Krawczynski et al. 2004

  18. In case you still thought things were simple… Mkn 421 2002 X-ray/TeV campaign (Dieter Horns, preliminary) X-ray Counts TeV X-ray hardness ratio (spectrum)

  19. Presentation by F. Aharonian, HEAD 2006 PKS 2155-304: remarkable flares in July/August 2006 July 27 17 Crab preliminary July 29 preliminary July 27 1Crab night by night lightcurve July-August 2006 2 minute binning lightcurve X-ray (RXTE, Swift, Chandra) observations available: Chandra – simultaneous coverage for 6 continuous hours ! strong variability - a factor of 2 timescales – 10 minutes or so) strong evidence for variability on a few minute timescales ! on average 70 g /min rate  spectrometry on minute timescales finally !we do have simultaneously obtained keV/TeV data for proper modelling of blazar jets (maybe) see poster by L. Costamante

  20. MAGIC : 10 min var. in Mkn 501? Albert et al. 2007 (astro-ph/0702008)

  21. TeV Blazars: Self-Consistent Modeling & Klein-Nishina Correction to Thomson Cross-Section Important! Response to variations in electron acceleration luminosity. E_p determined by t_cool=t_esc E_p determined by E_min (t_esc=infinity) IR/O Absorption (big effect!) Lots of soft target photons Solid line models: Both fit April 16th Mrk 501 CAT gamma-ray and BeppoSax data above 2 keV equally well… HARD spectrum Fewer and fewer soft photons

  22. What if we try to add some external photons to boost IC flux? If in KN limit, doesn’t work! If not, get too hard spectrum? concave up … 1ES 1426?

  23. Theoretical Considerations [Complications] V. • Assume simplest scenario: • e- directly accelerated, no protons, no photon-photon pair production. • UV/X-ray = synchrotron • GeV/TeV = Compton What are seed photons for Compton upscattering?? • Synchrotron Photons (SSC) • Accretion Disk Photons (ERC) • BLR Photons (reprocessed accretion disk photons) .. • IR photons from hot dust in central region .. • [Microwave background, probably not relevant, but .. • always there ] All possible => different gamma-ray spectra for same e- distribution! If you think you can a priori predict a gamma-ray spectrum, I have a deal for you…

  24. Effect of EBL absorption on source modeling… TeV blazars, e.g., Mkn 501, are very nearby (z~0.03) => Absorption not important? Wrong … don’t ignore! Mkn 501: absorption corrected spectrum EBL [Coppi&Aharonian 1999] [See also Dwek & Krennrich ]

  25. L. Costamante

  26. EXIST GLAST VERITAS Mrk 501 (1ES 1959+650)Mrk 421 RXTE ASM 3 hrs 1 Month IACT 2 Years Next Few Years Promising for Bright TeV Blazars … Krawczynski, 2004

  27. Example of Data Quality Expected for Next Generation Instruments – Model used for simulation (tcool) is slightly different at low energies compared to fit model (high gmin). Both models give excellent fit to current data – but not tosimulated HESS data! Simulated 5hr observation of April 16,1997Mrk 501 flare as would be seen by HESS.

  28. Two components! • Optical polarized • Synchrotron • TeV+ electrons! Uchiyama et al. 2007

  29. Another quasar jet (1136) … Uchiyama et al. 2007

  30. The X-ray/Radio correlation … Are “low” luminosity AGN interesting? Yes…. GX339 - Corbel et al. 2004 AGN !? - Maccarone et al. 2003

  31. A “boring” object in the sky: the nearby elliptical galaxy M87 Radio Optical

  32. HST M87 Superluminal Motion

  33. M 87 –evidence for production of TeV g-rays close to BH • Distance: ~16 Mpc • central BH: 3109 MO • Jet angle: ~15-30°  not a blazar! • discovery (>4s) of TeV g-rays by HEGRA (1998) confirmed by HESS (2003) F13 = 10-13 cm-2 s-1 TeV-1 F. Aharonian, HESS

  34. X-ray (Chandra) nucleus knot A HST-1 M87: light curve and variabiliy X-ray emission: • knot HST-1[Harris et al. (2005),ApJ, 640, 211] • nucleus(D.Harris private communication) I>730 GeV [cm-2 s-1] short-term variability within 2005 (>4s) constrains size of emission region (R ~ 5x1015dj cm) F. Aharonian, HESS

  35. Aside: Can use M87 [Cen A?] to probe diffuse background at MIR /FIR wavelengths with Eg > 10 TeV g-rays! F. Aharonian

  36. ??? [ Jet composition???] But… (e.g., Blanford-Znajek mechanism)

  37. TeV gamma-rays from Galactic Center G0.9 Sgr A* if extended source - size less than 3’ (7 pc) if point-like source – position within 1’ around Sgr A* HESS, F. Aharonian

  38. Most sources can think of, even decaying/annihilating CDM particles, trace large scale structure… look for clustering signal/cosmic web (anisotropy)! Bromm et al. 2003, cosmological structure formation calculation The rarer/more biased the source, the stronger the clustering signal!

  39. Response to Change in IR/O Background GeV background measurement = calorimeter for VHE universe! Key GLAST measurement “GZK” cutoff? Coppi & Aharonian 1997

  40. The big payoff from understanding AGN: Remove “spurious” sources and… An accurate measurement (upper limits) on the GeV-TeV extragalactic diffuse background. Why so interesting? GeV-TeV+ gamma-rays only produced in extreme environments or by “exotic” processes: e.g., black hole jets, supernova blast waves, cosmic strings, relict particle decays, or matter-antimatter annihilation. Background is sum of all nearby GeV-TeV activity in the Universe + all > GeV activity at z > 1. [ Gamma-ray pair production and cascading on intergalactic photon fields GLAST = calorimeter for VHE-EHE Universe! (best limits on BAU/matter-antimatter domains from gamma-rays) ]

  41. Find (HAWC) and follow low duty cycle flaring activity. Monitor synchroton peak up to ~MeV! Theorist’s Wish List (for AGN) Rule of thumb: give a theorist a spectrum consistent with a power law (e.g., due to insufficient statistics) and he can fit any model/EBL you like. Need to detect curvature! Ideally measure both sides of low and high energy peaks, simultaneously w/good (< hour-month) continuous time-sampling: UV-MeV, 100 MeV-TeV coverage. [Also very good to get below IR/O absorption threshold – N.B. EBL absorption not dependent.] ? Pian et al. 1998

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