Super Massive Black Holes 1 How do cosmic

Super Massive Black Holes 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 • 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 M 87; already see dramatic changes on scales of Rsch; phased-ALMA critical • Outstanding synergy with Fermi g-ray telescope…same particles produce g-rays also radio photons. While g-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 gray flares

Super-Massive Black Hole Accretion Disks 1. Do SMBHs control galaxy evolution (via AGN feedback)? 2. How do AGN accretion disks work? NGC 4258 • Sub-pc resolution imaging of AGN accretion disks via H 2 O masers (~150 now known) with 3 D velocities • “Gold Standard” black hole mass measurements; test and calibrate the MBH-s relation (s. M ~ few%) • Seyfert galaxy MBH~ 107 Msun fall below M-s relation • Get physical parameters of accretion disks (possibly to high-z): limits on disk mass T ~ 103 K and n ~ 109 cm-3 (to allow masing) B-fields possible from Zeeman effect Causes of warps; spiral structure?

Stellar Black Holes 1. How do black holes form and evolve? 2. Did Einstein have the last word on gravity? • 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+61 o 303) mystery; VLBA cometarylike pulsar-wind nebula, but no pulsations found. g-ray light curve evolving, unlike pulsar. What is going on? Cygnus X-1

The Milky Way 1. What Is the kinematic and spiral structure of the Milky Way? 2. What are the masses of its (disk, bar/bulge, halo) components? • Parallaxes/proper motions of masers in star forming regions will accurately trace spiral structure • Determine fundamental parameters, R 0 and Q 0 • Nearly 50 high-mass star forming region parallaxes measured with VLBA and VERA • More than ~300 22 -GHz H 2 O and ~1000 6. 7 -GHz CH 3 OH masers known…no shortage of sources

Star Formation 1. How do low mass and massive stars form? 2. How do accretion disks work and drive outflows? Orion Source-I • 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 3 D velocity information • OH masers: full Zeeman effect (potential for 3 D B-field) • VLBI masers maps synergistic with EVLA & ALMA for highmass star formation studies

Cosmological Parameters 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? • Rotational parallaxes (eg, M 33) allow better calibration of Cepheid P-L-metallicity relation • Direct measurement of H 0 from megamaser H 2 O maser (Megamaser Cosmology Project): ~150 known; so far 8 good for distance measurements • Goal: 10 galaxies each with s. 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 finestructure “constant” and proton-electron mass ratio; need highest angular resolution to isolate absorption compnents UGC 3789

Galaxy Interactions and Mergers 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? • 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!

Physics of Explosions and Ultradense Matter 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? • 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(g-ray) vs. L(spindown), if equal, can get moment of intertia…M(r)

Exosolar Planets 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? • 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

The Earth as a Planet, Solar System & Reference Frames 1. What is the Earth’s rotation, gravity field and internal structure? 2. What are asteroid shapes and spins? • EOP measured using VLBA & other antennas • VLBI only technique for the fundamental celestial and terrestrial reference fames and UT 1 • 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”

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

Other VLBI Networks 1. What role does the VLBA play in worldwide VLBI ? • VLBA strengths: Dedicated array/uniform data/always available Parallax scheduling, transients… Good high frequency performance Near-realtime multi-frequency observations Good (u, v) coverage/imaging/high resolution Very flexible correlator, eg, optimum pulsar gating; multi-position correlation • EVN strengths: Large number of antennas Large collecting area Good low-frequency performance e. VLBI realtime operation • VERA strengths: Dedicated for astrometry: already 25 parallaxes Simultaneous dual-beam observations

Other VLBI Networks 1. What role does the VLBA play in worldwide VLBI ? • HSA strengths: Highest sensitivity (s. S ~ 1 m. 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: Meer. KAT will be a 100 -m class VLBI station, plus other African telescopes may join VLBI efforts 3 mm-VLBI (14 antennas) studies most variable AGN emission China’s 4 antennas joining arrays; soon Shanghai 65 -m and then FAST • Event Horizon Telescope (EHT): Image dynamic region @ “event horizon” resolution

State of the “VLBI Union” 1. How can we reduce the budget deficit? 2. Can we increase competiveness? • 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”

What to do? 1. How can we raise revenue and/or cut costs? • Fermi contribution (why not spend 10% of 8 M$/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 = 10 2. 20 – 40% degradation for 8 vs 10 antennas 3. No obvious antenna(s) to drop: SC poor @ highfreq, but important for NS beam @ low freq 4. Even for astrometry only, some sources done with “inner-5” when maser spots are large