PROGRESS TOWARD A VLBA MOVIE OF THE JET

COLLIMATION REGION IN M87

R. Craig Walker NRAO

Collaborators:

Chun Ly (UCLA - was NRAO summer student)

William Junor (LANL), Philip Hardee (U. Alabama)

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

M87 Inner Jet

43 GHz Global VLBIJunor, Biretta, & Livio 1999, Nature, 401, 891

Shows hints of jet collimation region

Black Hole / Jet Model

Global VLBI Image

VLA Images

Resolution 0.000330.00012

JET FORMATION:BASE OF M87 JET

STScI

M87 43 Hz Images at ~1 yr Intervals

• 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

Our old observationsand archivedata. Mostly from use of M87 as phase reference source.(Ly, Walker, & Junor, 2007, Ap. J. 660, 200.)

• Basic edge brightened structure maintained

• Dominant edge shifts from south to north

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

Pilot Project Images

• 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

Day 0

Day 3

Day 10 Day 97

Day 35

Day 13No PT

M87 43 GHz Pilot Movie 97 Days

• Actual observations at the tick marks• Note the movie frame rate varies

• 0.8% on peak• Polarized peak

offset from total intensity

• Position angle rotates

• Polarization not detected off peak

Polarization Structure

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

The VLBA 43 GHz M87 MovieFirst Frame Jan 27, 2007

Beam: 0.40x0.20 mas 0.2mas = 0.016pc = 60Rs

1mas/yr = 0.25c

No KP

The VLBA 43 GHz M87 MovieSecond Frame - Low resolution version

Feb 17, 2007

Beam: 0.56x0.41 mas 0.2mas = 0.016pc = 60Rs 1mas/yr = 0.25c

MK bad weather

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