1. The continuing saga of the explosive event(s) in the M87 jet D. E. Harris, SAO collaborators/co-authors C. C. Cheung J. A. Biretta F. Aharonian L. Stawarz E. S. Perlman S. Wagner W. Sparks D. Horn A. S. Wilson K. Mannheim T. Bretz H. Krawczynski R. Mukherjee V. Vassiliev J. Carson

2. Girdwood - 2007 May 21 Reminder: when viewing radio - We think we see (distorted) view of emitting volumes containing relativistic electrons and magnetic fields. ‘distorted’ shape from projection effects & aberration ‘distorted’ intensity from relativistic beaming

3. Girdwood - 2007 May 21 When viewing an X-ray image - In addition to the same attributes as the radio, We are viewing acceleration regions: I.e. high energy electrons are being produced throughout the emitting volume.

4. Girdwood - 2007 May 21 outline UV/HST image, J. Madrid & W. Sparks Part I: X-ray LC of core, HST-1, knots D & A. - caveats are the instrumental effects. Part II: Superluminal proper motions of radio components within HST-1. Part III: The TeV connection.

5. Girdwood - 2007 May 21 Photometry Straightforward to separate core & HST-1 when there is no pileup - model the PSF w. ChaRT. First order recovery of piled events: weight each event w. its energy and sum 0.2-17keV; use evt1 file with no grade filtering (mitigate effects of grade migration)

6. Girdwood - 2007 May 21 keV/s light curves for core, HST1, knots D and A

7. Girdwood - 2007 May 21 Bleeding from release of trapped charge at readout time

8. Girdwood - 2007 May 21 Instrumental Problems Subtract 5% of HST-1 from the core. Bleeding from one side of PSF: release of trapped charge (not modeled). Other losses include ETN (eat-thy-neighbor), on- board filtering, and bits of piled events which are outside 3x3 pixel region.

9. Girdwood - 2007 May 21 Readout Streak Photometry Lousy s/n: we get the equivalent of 18s of CC mode from a 5ks observation by measuring ~40 rows. Background is high. Apparently, true peak is significantly higher than what we had thought.

10. Girdwood - 2007 May 21 The Radio Side Started VLA in 2003 To avoid data gaps when VLA is in C & D arrays, started VLBA in 2005.

11. Girdwood - 2007 May 21 Superluminal Proper Motions The inner (vlba) jet is not known to be superluminal. HST-1 has ß=v⁄c≈4 for some components.

12. Girdwood - 2007 May 21 HST-1 4 epochs shown between 2005.0 and 2006.5 (we have about a dozen; more coming) New bits getting resolved and downstream bit moving

13. Girdwood - 2007 May 21 Trajectories on the sky A (blue) at 2.5c, then decelerates to 1.4c B (green) trails A, same velocity, but different PA. C (red & magenta) splits into 2 components with c1 (magenta) moving faster, at 4.3  0.7.

14. Girdwood - 2007 May 21 The TeV connection HESS group reported a higher gamma ray flux in 2005. They argued that because of rapid variability, the likely origin was the nucleus (close to SMBH) in spite of apparent similarity of X-ray and  -ray light curves.

15. Girdwood - 2007 May 21 Evidence that the HESS  -rays originated in HST-1 rather than from the nuclear region. The X-ray LC for HST-1 peaked at the same time as the  -ray high state. IC is a mandatory process of any relativistic plasma: both starlight and the synchrotron spectrum are most prominent ≈10 14 Hz; TeV emission is expected from  =10 6 electrons, and the expected intensity is approximately what was observed. The IC and synchrotron spectral indices have similar values. The photon-photon opacity for the alternate location near the SMBH is much greater than 1.

16. Girdwood - 2007 May 21 Short Timescale Variability As often happens, the data are ambiguous. In principle we could use similarities in light curves to decide the origin of the  -rays. In practice, there is not enough overlap.

17. Girdwood - 2007 May 21 To what extent is M87 a Blazar? Defining characteristics: Large change of amplitude (“flare”); Associated generation of superluminal blobs; Associated VHE emission. Idiosyncrasies: M87 timescale is longer than typical blazar

18. Girdwood - 2007 May 21 FIN Nature has been fairly kind: after we find something unique like the first pulsar, we then find many more and are able to study the class of these objects. In the case of M87, it thus seems either the flare of 2005 is unique and we now have to search for similar events in other jets (nothing like this has so far been detected in the Cen A jet, despite many observations over many years), OR it is just an individual member of a known class (e.g. blazars), albeit with some extreme values.