PROGRESS TOWARD A VLBA MOVIE OF THE JET COLLIMATION REGION IN M87

1. PROGRESS TOWARD A VLBA MOVIE OF THE JET COLLIMATION REGION IN M87 Collaborators: Chun Ly (UCLA - was NRAO summer student) William Junor (LANL), Philip Hardee (U. Alabama) R. Craig Walker NRAO

2. Why Study the Jet Base in M87 • Best case for a study of a jet near a black hole • “Near” in terms of characteristic lengths of system • The galaxy is relatively nearby at 16 Mpc • Large black hole mass ~3X109 Msun • VLBA resolution is about 60 Schwarzschild radii • Core has about 1 Jy at 43 GHz • Jet bright enough to see significant structure • Well resolved across jet very near core • Wide range of speeds seen in the jet on larger scales • Includes 6c superluminal speeds which suggest a jet orientation near line-of-sight • VLBI measured speeds mostly subluminal • Wish to compare observations with theory and numerical simulations

3. M87 Inner Jet JET FORMATION:BASE OF M87 JET VLA Images 43 GHz Global VLBI Junor, Biretta, & Livio 1999, Nature, 401, 891 Shows hints of jet collimation region Resolution 0.000330.00012 Black Hole / Jet Model Global VLBI Image STScI

4. M87 43 Hz Images at ~1 yr Intervals Our old observations and archive data. Mostly from use of M87 as phase reference source. (Ly, Walker, & Junor, 2007, Ap. J. 660, 200.) • Rates 2001.78 - 2002.42 are 0.25 - 0.40c • 1.0 to 1.7 mas/yr • Other epochs too widely spaced • Feature seen east of core - counterjet or inner jet? • If counterjet, speeds and brightness give orientation • 30-45 deg to line-of-sight, 0.3-0.5c • Result inconsistent with constraints from superluminal motion observed on larger scales Basic edge brightened structure maintained Dominant edge shifts from south to north

5. PILOT PROJECT • Wish to make a VLBA movie to study dynamics • Previous data showed 1 year intervals are too long. • Rate ≥ 0.25 - 0.4 c (up to 1.7 mas/yr) • Did not know the appropriate frame rate • Superluminal speeds would require sampling every few days • Up to 6 c (24 mas/yr) seen on larger scales • Pilot project: • Observations at 0, 3, 10, 13, 35 and 97 days • Observed April - July 2006 • 43 GHz, 10hr observations, 128 Mbps

6. Day 0 Day 13 Day 3 Day 35 Day 10 Day 97 Pilot Project Images No PT • Good consistency between close epochs • Motions near 2.2 mas/yr (0.6c) at 1.5 mas from core • About 1.5 mas/yr near core • Superluminal motions not seen • Feature east of core still seen Beam: 0.42x0.18 mas 0.2mas = 0.016pc = 60Rs 1mas/yr = 0.25c

7. M87 43 GHz Pilot Movie 97 Days • Actual observations at the tick marks • Note the movie frame rate varies

8. Polarization Structure • 0.8% on peak • Polarized peak offset from total intensity • Position angle rotates • Polarization not detected off peak

9. The VLBA 43 GHz M87 Movie • Scheduled for 18 frames at 3 week intervals • Interval based on Pilot Project results • Dynamic scheduling within windows • Observations began Jan. 27, 2007 • Five frames observed and correlated so far. Two imaged • Frame 1 Missing Kitt Peak - weak on sort baselines • Frame 2 bad weather at Mauna Kea - reduced resolution • Observational parameters • 10 hr/frame • 256 Mbps (Twice the bandwidth of pilot) • Full stokes • Primary calibrators 3C279 and OJ287

10. The VLBA 43 GHz M87 MovieFirst Frame Jan 27, 2007 No KP Beam: 0.40x0.20 mas 0.2mas = 0.016pc = 60Rs 1mas/yr = 0.25c

11. The VLBA 43 GHz M87 MovieSecond Frame - Low resolution versionFeb 17, 2007 MK bad weather Beam: 0.56x0.41 mas 0.2mas = 0.016pc = 60Rs 1mas/yr = 0.25c

12. The VLBA 43 GHz M87 MovieNot much yet, but here’s the start Beam: 0.40x0.20 mas 0.2mas = 0.016pc = 60Rs 1mas/yr = 0.25c