1. Gabriele Giovannini Dipartimento di Astronomia, Bologna University Istituto di Radioastronomia - INAF EVN observations of M87 as follow-up on a recent TeV flare In collaboration with M. Giroletti & C. Casadio – IRA-INAF Bologna M. Beilicke & H. Krawczynski Phys. Dept. – Washington, MO A. Cesarini School of Physics, Univ. Of Ireland Galway

2. 1 mas 5 mas Krichbaum 43 GHz 86 GHz M87 – A well known friend Good resolution –Nearby: 16.7 Mpc –Large black hole mass: ~6X10 9 M sun –Scale 1 mas = 0.081pc = 140 Rs. Well studied at all wavelengths from radio to TEV Walker

3. core HST-1 500 pc

4. A VHE у-ray emitting: 2003-2006 by HESS – variability on time scale of days in high state data (Aharonian et al. 2006)  promising possibility of TeV production it is the nucleus However HST-1: in the X-ray increased by more than a factor 50 2001-2006 with a major flare on 2005 Superluminal motions of radio features in HST-1 (Cheung et al. 2007) Harris et al. 2009

5. in February 2008 M87 showed a strong VHE у-ray activity: multiple flares, short term variability. HST-1 was in a low state (in X-ray) Nucleus in its highest state since 2000 (Acciari et al. 2009) 2005 TeV flare with radio flare of HST-1 2008 TeV flare with radio flare of the nucleus In this scenario we started a program of e-EVN observations at 5 GHz – large field of view – high sensitivity - high resolution: 2009 Nov. 19 2010 Jan 27 2010 Feb 10 high flux level at > 100 GeV: MAGIC ATel 2431 2010 March 6 2010 March 28 Apr. 9 strong flare VERITAS/MAGIC 2010 May 18 2010 June 9 not yet reduced

6. Results for the core/inner jet region: No visible proper motion from our eEVN data Orientation: literature data: Acciari et al. 2009: 15 – 25 degree We estimate from j/cj brightness and assuming limb-brightened as due to a velocity structure (different Doppler factor) : 20 o – 30 o Core dominance: core radio power lower than expected from the unbeamed total radio power M87 3C192

7. core flux density at 5 GHz from our eEVN data (HPBW 8x3.4 mas): November 19 - 2009 1.81 Jy ± 0.03 January 27 - 2010 1.81 February 10 - 2010 1.80  VHE activity March 6 - 2010 1.89 March 28 - 2010 2.01  VHE activity Apr. 9th May 18 - 2010 1.93 waiting 1 more epoch (June 9)

8. Optical 1995 VLA 1995 15 GHz 3mJy/beam VLA 15 GHz 2008.9 28 mJy/beam Harris et al. 2006 HST-1 First detected in optical (Perlman et al. 1999),

9. Peak flux density: 2009.87 3.5 mJy/beam 2010.07 2.7 Total flux density ~ mJy 2010.11 3.0 Total VLA at 8.4 GHz: 45 mJy 2010.17 4.6 in 2008.9 2010.25 3.4 2010.38 2.8 HST-1 well detected in our e-EVN images Jan 27 2010 HPBW 8x3.4 mas

10. VLA: unresolved VLBI: peak Chang et al.2010 Cheung et al. 2007

11. CONCLUSIONS from new e-EVN and literature data Despite of activity and brightness of M87 nuclear region, the radio core dominance is low in comparison with 3CR and B2 radio galaxies The radio core flux density at 5 GHz (HPBW 8x3.4 mas) is constant November 2009– February 2010, after (March) is increasing: 2013 mJy on March 28, and 1.93 on May 18th The HST-1 structure in eEVN images is well resolved in many substructures, variable in time, in morphology and flux density in agreement with previous VLBA images

12. From inhomogeneous VLBI data (different angular resolution, frequency and network) the HST-1 brightest feature was moving at 0.5 – 0.6 c before 2005.5 and at 2.7 c after 2005.5 A collective HST-1 proper motion is confirmed by high resolution VLA data from 2003. The HST-1 kinematic is complex The HST-1 apparent velocity 2.7c implies an intrinsic velocity = 0.94c with an orientation angle of 20 degree. This velocity is in agreement with general FR I jet properties at about 150-170 pc (deprojected) from the core A more regular and longer multifrequency comparison is necessary to understand nuclear and HST-1 propertiers in M87

13. THANK YOU