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

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

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

Moderski et al [~MeV] 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 harder than 0.5! ERC, UV blackbody seeds EGRET blazars?

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!

Origin of alpha_x < 0.5 in EGRET blazars never resolved (and seen in more blazars than EGRET ones) – “slow cooling” interpretation has problems during flares. Watch out for Klein-Nishina effects! (alpha_x< 0.5,  sync,peak -  IC,peak mapping messed up, x-ray bump does not imply new e- component) Simultaneous X-ray luminosity/spectrum also constrains cascade/hadronic models. 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.) Summary

Acceleration to eV close to the gravitational radius (10 12 – cm) UHE neutrinos – detectable by AUGER ? Maybe UHE neutrons?? g interaction with IR and mm photons (and B) fields => E-M cascades no conflict with X-rays ! requires 10 kG B-field at 1-2 Rg F. Aharonian N.B. For PIC, bulk of luminosity in neutrinos (good) but neutrinos don’t cascade (in AGN) = bulk of luminosity at ~threshold energy (bad for ICECUBE?) Sample calculation

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 plasma neutrinos very slow process:  protons interacting with photon fields neutrinos* low efficiency + severe absorption of TeV  -rays  proton synchrotron no neutrinos very large magnetic field B=100 G + accelaration rate c/r g “extreme accelerator“ (of EHE CRs) Poynting flux dominated flow unlikely * detectable neutrinos from EGRET AGN but not from TeV blazars F. Aharonian

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

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

A Generic VHE Source …. Process(es) directly responsible for observed X-ray/  -ray emission? lowest order, most “efficient” IC or   Multiwavelength observations very powerful/critical! E.g., if have synchrotron/IC model L IC /L syn =U B /U rad, constrain B if know U rad. Also, correlated IC/synch. spectra!

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

The “ Boring” TeV Blazars

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

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

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

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

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

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

PKS : remarkable flares in July/August 2006 see poster by L. Costamante July 27 July 29 night by night lightcurve July-August 2006 preliminary 2 minute binning lightcurve July Crab 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) 1Crab strong evidence for variability on a few minute timescales ! on average 70  /min rate  spectrometry on minute timescales finally ! we do have simultaneously obtained keV/TeV data for proper modelling of blazar jets (maybe) Presentation by F. Aharonian, HEAD 2006

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

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

concave up … 1ES 1426? 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?

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…

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 ]

L. Costamante

Next Few Years Promising for Bright TeV Blazars … Krawczynski, 2004 Mrk 501 (1ES ) Mrk Years 3 hrs EXISTGLASTVERITAS 1 Month RXTE ASM IACT

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

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

Another quasar jet (1136) …

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

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

HST M87 Superluminal Motion

M 87 – evidence for production of TeV  -rays close to BH Distance: ~16 Mpc central BH: 3  10 9 M  Jet angle: ~15-30°  not a blazar! discovery (>4  ) of TeV  -rays by HEGRA (1998) confirmed by HESS (2003)  13 = cm -2 s -1 TeV -1 F. Aharonian, HESS

M87: light curve and variabiliy X-ray emission: knot HST-1 [Harris et al. (2005), ApJ, 640, 211] nucleus (D.Harris private communication) X-ray (Chandra) HST-1 nucleus knot A I>730 GeV [cm -2 s -1 ] short-term variability within 2005 (>4  )  constrains size of emission region (R ~ 5x10 15  j cm) F. Aharonian, HESS

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

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

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

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!

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

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) ]

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 Find (HAWC) and follow low duty cycle flaring activity. Monitor synchroton peak up to ~MeV!