Super Massive Black Holes

• Outstanding synergy with Fermi -ray telescope…same particles produce -rays also radio photons. While -rays may dominate energetics, but VLBI can image what’s going on; eg, evidence that SLM traced back to “core”, not BH, at time of optical and -ray flares

• VLBI movies of AGN jets (eg M 87, blazars) provide the only way to image these amazing phenomena on scales down to the ergosphere of nearby SMBHs. • VLBA imaging surveys of >1000 AGNs! No new binary SMBHs found.• Jet acceleration ramps up over inner parsecs. Non-balistic motions common; mm-VLBI jet widths currently favor B-Znajek over B-Paine. Polarization imaging revealing jet-sheaths…extremely rich phenomenology. • “Event Horizon Telescope” VLBI can image with Rsch resolution for Sgr A* and M87; already see dramatic changes on scales of Rsch; phased-ALMA critical

1. How do cosmic accelerators work and what are they accelerating?2. What collimates jets and how do jets evolve and interact with their host

galaxy?

M 87

Super-Massive Black Hole Accretion Disks

1. Do SMBHs control galaxy evolution (via AGN feedback)?2. How do AGN accretion disks work?

• Sub-pc resolution imaging of AGN accretion disks via H2O masers (~150 now known) with 3D velocities• “Gold Standard” black hole mass measurements; test and calibrate the MBH- relation (M ~ few%)

• Seyfert galaxy MBH~ 107 Msun fall below M- relation

• Get physical parameters of accretion disks (possibly to high-z):limits on disk massT ~ 103 K and n ~ 109 cm-3 (to allow masing)B-fields possible from Zeeman effectCauses of warps; spiral structure?

NGC 4258

Stellar Black Holes

• VLBI parallaxes (+optical/x-ray data) accurate binary parameters and BH spins• Directly tracing binary orbits• Some BH’s may form without a bang!• Fermi HMXRB (LSI+61o303) mystery; VLBA cometary-like pulsar-wind nebula, but no pulsations found. -ray light curve evolving, unlike pulsar. What is going on?

1. How do black holes form and evolve?2. Did Einstein have the last word on gravity?

Cygnus X-1

The Milky Way

• Parallaxes/proper motions of masers in star forming regions will accurately trace spiral structure• Determine fundamental parameters, R0 and 0

• Nearly 50 high-mass star forming region parallaxes measured with VLBA and VERA• More than ~300 22-GHz H2O and ~1000 6.7-GHz CH3OH masers known…no shortage of sources

1. What Is the kinematic and spiral structure of the Milky Way?2. What are the masses of its (disk, bar/bulge, halo) components?

Star Formation

• Parallaxes (±1%) of low-mass stars throughout the solar neighborhood; without parallaxes get poor sizes of disks (25%), L and age (50%), mass (100%)• Resolve Pleiades distance controversy (Hipparcos vs. “rest of the world”)…main-seq fitting, stellar ages & evolution • Accurate masses, luminosities and ages of YSOs• Direct imaging of disk outflows with sub-AU resolution and 3D velocity information• OH masers: full Zeeman effect (potential for 3D B-field)• VLBI masers maps synergistic with EVLA & ALMA for high-mass star formation studies

1. How do low mass and massive stars form?2. How do accretion disks work and drive outflows?

Orion Source-I

Cosmological Parameters

• Rotational parallaxes (eg, M 33) allow better calibration of Cepheid P-L-metallicity relation• Direct measurement of H0 from megamaser H2O maser (Megamaser Cosmology Project): ~150 known; so far 8 good for distance measurements• Goal: 10 galaxies each with Ho ~ 10% 3% final uncertainty

Ho = 72 ± 5 km/s/Mpc for NGC 4258 (by re-cal’ing Cepheids)

Ho = 69 ± 11 km/s/Mpc for UGC 3789 (directly)Ho = 73 ± 7 km/s/Mpc for NGC 6264 (directly)

• Measuring spectral lines at high redshift test constancy of fine-structure “constant” and proton-electron mass ratio; need highest angular resolution to isolate absorption compnents

1. Can the extragalactic distance scale be improved?2. What is the value of Ho (and then w)?3. Do fundamental constants change over cosmic time?

UGC 3789

Galaxy Interactions and Mergers

• Proper motion measurement of Andromeda is key to the dynamical fate of the Local Group• Measurement of the masses of the dark matter halos of Andromeda and Milky Way• OH megamasers reveal galaxy mergers; maser clumps have dynamical masses of ~106 Msun

• No new binary SMBHs found in VLBA survey of over 1100 ANGs!

1. How Is matter distributed in the Local Group of galaxies?2. What is the history and fate of the Milky Way and the Local Group?3. What happens to SMBHs in merging galaxies?

Physics of Explosions and Ultradense Matter

• Distances (parallaxes) to neutron stars are key to determining their masses and radii, which combined can place strong constraints on the equation of state of ultra-dense matter.• Proper motions indicate birth places and ages of pulsars.• With parallax & DMs can model Milky Way ne

• Pulsar parallaxes sensitivity limited…need BW• For Fermi pulsars, D => L and comparing L(ray) vs. L(spindown), if equal, can get moment of intertia…M(r)

1. How do explosions work and what do they make?2. How do pulsars form, evolve, and emit?3. What is the equation of state of neutron stars?

Exosolar Planets

• RIPL: targets are low-mass nearby stars; can rule out planet >10 MJ @ 1 AU in only 10 days!

• Hints of planets in data. • Sensitivity limited…need more BW

1. Are planetary systems around low mass stars different from solar mass stars?2. What is fraction of long-period planets around low mass stars?

The Earth as a Planet, Solar System & Reference Frames

• EOP measured using VLBA & other antennas• VLBI only technique for the fundamental celestial and terrestrial reference fames and UT1• Quality of VLBA data improved ICRF by 60% !• Highest precision free-core nutation measures• Measure asteroid spin/shape, using short VLBA baselines, for possible manned “landing”

1. What is the Earth’s rotation, gravity field and internal structure?2. What are asteroid shapes and spins?

Space Craft Tracking

• VLBA positioning complementary to range-Doppler tracking…need VLBI array controlled at 1 location• Demonstrated <1 nrad (<0.2 mas); VLBI is most accurate space craft tracking method• Tracking Cassini improved mass estimate of Iapetus • Measured barycenter of Saturn to ±10 mas• IKAROS (solar-sail) tracked with Australian VLBI• Future can achieve <100 m lateral positioning

1. How well can we locate and track interplanetary space craft?2. Can we improve the rather uncertain orbits of outer planets?

Other VLBI Networks

• VLBA strengths:Dedicated array/uniform data/always available

Parallax scheduling, transients…Good high frequency performanceNear-realtime multi-frequency observationsGood (u,v) coverage/imaging/high resolutionVery flexible correlator, eg, optimum pulsar gating; multi-position correlation

• EVN strengths:Large number of antennasLarge collecting areaGood low-frequency performanceeVLBI realtime operation

• VERA strengths:Dedicated for astrometry: already 25 parallaxesSimultaneous dual-beam observations

1. What role does the VLBA play in worldwide VLBI ?

Other VLBI Networks

• HSA strengths:Highest sensitivity (S ~ 1 Jy)

Phased-EVLA soon• Japan/Korean (East Asian) VLBI

13 Japanese, 3 (new) Korean, 4 Chinese ants • Australian LBA; proud of international users!

12-m in New Zealand; ASKAP (36 12-m) will join at L-band

• Global Arrays:MeerKAT will be a 100-m class VLBI station, plus

other African telescopes may join VLBI efforts3 mm-VLBI (14 antennas) studies most variable AGN emissionChina’s 4 antennas joining arrays;

soon Shanghai 65-m and then FAST

• Event Horizon Telescope (EHT):Image dynamic region @ “event horizon” resolution

1. What role does the VLBA play in worldwide VLBI ?

State of the “VLBI Union”

• Increase revenues• Decrease expenses• Upgrade (or die)

Add capability (eg, 4,32,160 Gbps; C-band rcvr; wide-field correlation/surveys)

On path to SKA-high: “NAA”

1. How can we reduce the budget deficit?2. Can we increase competiveness?

What to do?

• Fermi contribution (why not spend 10% of 8M$/yr grant program as partial support for VLBA observations)• “Sell” more geodetic/geophysical time• Spacecraft tracking• NRAO “bake sale”• “Mission projects”: decrease user support;

users help with data quality assurance• Dropping antennas absolute last resort

1.Array designed for optimum (u,v)-coverage over all Declinations: minimum # of antennas = 102.20 – 40% degradation for 8 vs 10 antennas3.No obvious antenna(s) to drop: SC poor @ high-freq, but important for NS beam @ low freq4.Even for astrometry only, some sources done with “inner-5” when maser spots are large

1. How can we raise revenue and/or cut costs?