What have we learned? Outstanding questions… Philip Kaaret University of Iowa/Paris 7/CEA Saclay Comments `Little’ questions

Amir: “The more I know about these objects, the less I understand them”. Understanding 1 Knowledge (observational) Time evolution of Levinson Goal of workshop

What have we learned? There may or may not be a blazar sequence Photons may or may not breed Jets may or may not contain hadrons Jets may or may not have helical B fields One Finn may not drink on May day Blazars may or may not have observable disks X-ray flares may be produced upstream of the VLBI core or maybe downstream GLAST may or may not launch in May We’re all indebted to Mrk 421 and 501 (and that was just the first half of the workshop)

What are we studying? (Marscher) Input from disk to base of jet is noise (McH). If jet is a linear process, then output of jet will match input. However, differing variability at different energies in jet output argues against a linear process. Disk’s don’t make TeV photons. (Marscher) The inner regions of the disk produce a `blob’ of energy and matter (BH spin may help push) that is then accelerated in the jet and produces radiation.

What is the input from the disk? Single blob Multiple blobs Stream (Henri) From known variability of accretion disks (McHardy), the input has a red noise spectrum and a log-normal distribution of amplitudes.

Does the variability in the jet arise from the disk input or internally in the jet?  Photons If jet is linear, then jet variability = disk input and jet variability should be same at all energies – not seen. For non-linear jet, disk noise will affect jet variability – some jet variability seen may be produced in the disk. Realistic blazar variability modeling should start with injection of blobs with a disk noise spectrum and log-normal amplitude distribution. Study of blazars is mainly study of the processes occurring in the jet (it’s ok if the input is noise).

Links between Disk and Jet Eikenberry et al. 1998, 2004 Simultaneous IR (jet) and X-ray (disk) observations of the stellar-mass black hole GRS 1915+105 show that jet ejection is tightly correlated with rapid disappearance of the inner accretion disk. Note disk and jet vary at same time scale and both with large amplitudes.

Disk/Jet Links Inner disk disappears, few 100 s later, IR starts to rise Swank et al. 1998, Mirabel et al. 1998.

Corbel et al. 2002, Kaaret et al. 2003 Jets of XTE J1550-564 X-ray Corbel et al. 2002, Kaaret et al. 2003 Radio jets (Hannikainen+ 2001)

Individual SEDs are not sufficiently constraining. Six times 3C 279 6/1991 From Esko Valtaoja Valtaoja Individual SEDs are not sufficiently constraining.

Simultaneous spectra? (Henri) Fitting of individual SEDs may even be misleading because the instantaneous spectrum (in our frame) likely arises from spatially separated regions. (Henri)

Need time dependent models Henri >200Gev flux from Hess

Need time dependent models Valtaoja

Designing a multiwavelength campaign Reliable inferences about correlations can be made only if the monitoring duration is many times longer than correlation delay and flare duration. X-ray/optical lags of ±20 days (3C279, Marscher) X-ray/radio lag of 114 ± 21 days (3C279, Marscher) TeV/X-ray lag < 30 min (PKS 2155, Benbow) X/ray/X-ray lag ~ 300 min (Sato) Need long durations to compare optical/radio with X/-ray Short durations OK for X versus -ray Need variability  study flares, ok if statistical nature of process is understood (Degrange)

Optical and radio are better done as dedicated monitoring programs Optical monitoring (Tosti and posters) Perugia (VRI), Colgate, Turin, Rome, Turku (public light curves?), Rem at La Silla (JHKVRI), Georgia State, Calar Alto, WEBT, KANATA/Trispec (optical/IR w/polarimetry) Radio monitoring Metsähovi (fluxes), BU (images), need more radio (in southern hemisphere or near equator) Coordinate via Blazar MWL Wiki castor.adlerplanetarium.org/MWL More people using your data means more publications for you.

X- and -ray monitoring GeV - GLAST TeV – Whipple, DWARF X-rays – MAXI (Kataoka) Use these HE monitors to trigger TOOs with pointed X-ray satellites and big TeV telescopes Add occasional coverage in extra optical to radio bands? Need radio in south?

Frequency resolved spectroscopy Technique to isolate emission components Giebels Gilfanov+ 2003

Big Questions How are jets formed and collimated? Are jets electron/hadron or electron/positron? Are jets purely accretion powered or can jets extract energy from the rotation of a black hole? What is the role of magnetic fields? Can particles be accelerated to TeV energies without a jet (Sol)?

`Little’ Questions How large is the magnetic field in jets? What is the configuration of B in jets? (Gabuzda) What is the average luminosity of a given blazar? What fraction of the accretion power goes into jets? (Perlman) Can blazar light curves be decomposed using a `universal’ shape? Is the shape the same for different energies? What can we learn from the shape? (Valtaoja, Moderski) Do TeV flares really have very high Doppler factors? Do (some) particles thermalize at the shock front (Kirk) Should we develop new timing tools (i.e. for data with variable size time bins)? (Degrange, Wagner, Madejski) How can we resolve the question of the composition of the jets? (Mannheim)

What is the magnetic field in jets? Numbers mentioned from 100 G to 100 G. Ways to measure: X-ray flare shape? (Kataoka) Turnover frequencies in submm-infared? (Mannheim) Optical circular polarization? Radio polarization? (Gabuzda) Modeling of SED? Can we measure the B field of interest? ‘Structured’ B in structured jet? Radio/optical measurements relevant for X/-ray emitting regions?

What is a blazar’s average luminosity? Correct corrections for relativistic motion. (Dermer) What are the duty factors of blazars in various energy bands? Should we make the blazar sequence using the peak or average luminosities? (Benbow)

Minimal time interval for 5 σ flux measurement as a function of flux in H.E.S.S. observations of PKS 2155-304 log(Δt ) Background-limited sensitivity Degrange Statistics-limited sensitivity Flares log(Flux)

Events during meeting ~40 News stories via google “Marscher black hole jet”. Successful first year of Agile

Conclusions All of the theories have explained all of the data All of the observations have ruled out all the theories.